embedding of shock wave reactor in thermal cracking

Embedding of Shock Wave Reactor in Thermal Cracking Process for Ethylene

May 2007 Erdin Kocak

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Embedding of Shock Wave Reactor in Thermal Cracking Process for Ethylene

Delft, May 2007 Ing. Erdin Kocak Delft University of Technology (TUD), Hoogvlietstraat 22 Department of Chemical Technology 3081 SV Rotterdam and Material Science, Tel: 0618525974 Sub-Faculty Chemical Process Technology Studentno: 1193457 Section Product & Process Engineering Supervisors: Dr.ir. P.J.T. Verheijen (TUD) Ir. Ing. Marco van Goethem (TUD) Dr.ir. J.R. van Ommen (TUD)

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Preface

I would like to thank Marco van Goethem for al the effort he took to help me with this project. It was a very learning project. I also want to thank Peter Verheijen and Ruud van Ommen. My biggest thanks go to my parents, which helped me to take a proper education.

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Summary The goal of this project was to embed the Shock Wave Reactor (SWR) into an ethylene plant in order to assess the performance of this unique reactor. The performances are based on the energy consumption and ethylene yield. There are some researches done. Unfortunately no information is found in articles about how to embed the SWR in an ethylene plant. So, to embed the SWR, the behavior of the whole plant must be monitored. The embedding of the SWR in an ethylene plant is done by integration this reactor in an ethylene plant based on conventional cracking. Conventional cracking is done by a furnace. The only different is the cracking reactor. The separation configuration is taken the same. Strong GDP (gross domestic product) growth in major regions results in strong petrochemical demand growth. The reason of this growth is due to the growing market of China and India. So the importance of ethylene increases. Ethylene is and in the future still be an important bulk chemistry in the petrochemical and industry The process chemistry with its thermodynamics and kinetics are based in earlier research done by R.Bosma. Normally more than 1 million reactions occur during ethane cracking but here 7 major reactions are used. The residence time plays a big role in this cracking. Thermodynamically high temperature is favorable but kinetically not. High temperatures increase the secondary reactions with more by-products as result. The SWR was already modeled in Matlab by R.Bosma [21]. To investigate the SWR energy consumption, the SWR is modeled in Aspen. A user model in Aspen has been made, which reflects the behavior of the SWR at some given conditions. This Aspen model is validated in order to determine the reliability of this model. The model is successfully made but some parameters where slightly different. With Aspen Pinch, the determination of the energy consumption is made. This is very important because the energy consumption will conclude if this SWR economical favorable compared with a conventional furnace. Also the environmental impact of the SWR has been studied. It is known in the aviation industry, shock waves produce a lot of sound power. It can have a certain risk to the human health and environment. This is a complex problem because of the difficulties to monitor the sound behavior of this reactor. It is concluded that the SWR is an energy slurping process compared with a conventional furnace. The ethylene yield is also lower than the ethylene yield produced with a conventional furnace.

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Nomenclature

SWR Shock Wave Reactor GDP Gross Domestic Product SDF Steam Dilution Factor TLE Transfer Line Exchange NRC Noise Reduction Coefficient TC0 Reservoir temperature of the Shock Wave Reactor (K) TC1 Pyrolysis temperature (K) T2 Temperature after mixing the hydrocarbon with steam (K) T3 Temperature after shock (K) P Overall sound power (W) P0 Reference value sound power (10-12) Lw Overall sound intensity (dB) Ei Activation energy (kJ/mole)

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TABLE OF CONTENT 1 Introduction.........................................................................................................11

1.1 Importance of ethylene ................................................................................11 1.1.1 Ethylene production from different feedstock’s ..................................12 1.1.2 Gas Feeds [9] .......................................................................................13

1.2 Shock wave reactor......................................................................................14 1.3 Objective research .......................................................................................15 1.4 Research approach .......................................................................................15 1.5 Content chapters ..........................................................................................16

2 Process options and selection .............................................................................18 2.1 Process chemistry ........................................................................................18

2.1.1 Thermodynamics..................................................................................18 2.1.2 Kinetics ................................................................................................19

2.2 Shock Wave Reactor....................................................................................21 2.2.1 Process description...............................................................................21 2.2.2 Shock Wave Reactor configuration .....................................................21

2.3 Conventional steam cracking of ethane.......................................................24 3 Validation Shock Wave Reactor .........................................................................26

3.1 Shock Waver Reactor in Matlab and ASPEN .............................................26 3.1.1 Variation of the parameters..................................................................26

4 Modeling of the SWR and conventional furnace reactor in Aspen ..................28 4.1 Objective......................................................................................................28 4.2 Ethylene plant with a conventional furnace.................................................28 4.3 Ethylene plant with a SWR..........................................................................29 4.4 Configuration utilities used for separation ..................................................30

5 Energy consumption ...........................................................................................33 5.1 Energy consumption with a conventional furnace.......................................33

5.1.1 Variation of the furnace temperature ...................................................34 5.2 Energy consumption with a SWR................................................................37

5.2.1 Variation of the SWR steam temperature ............................................38 5.2.2 Variation of the residence time............................................................39 5.2.3 Variation of the SWR Mach speed ......................................................41 5.2.4 Variation of the SWR pressure before shock.......................................43 5.2.5 Variation of the SWR SDF ..................................................................45 5.2.6 Comparison energy consumption SWR and furnace...........................47

6 Environmental impact.........................................................................................50 6.1 Sound power calculation..............................................................................50 6.2 Enclosure of the SWR with a bunker ..........................................................52 6.3 Vibration control SWR................................................................................53

7 Conclusion and recommendations .....................................................................54 7.1 Embedding of the SWR...............................................................................54 7.2 Energy consumption ....................................................................................54 7.3 Ethylene yield ..............................................................................................54 7.4 Sound and vibration control.........................................................................55 7.5 Recommendations........................................................................................55

Appendix......................................................................................................................58 Appendix A Determination Nozzle and mixing configuration..................................59 Appendix B Shock property calculation.....................................................................62 Appendix C Determination pyrolysis section SWR....................................................63

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Appendix D Input values used to determine accuracy of the Aspen SWR model ....68 Appendix E Output values used to determine accuracy of the Aspen SWR model ..70 Appendix F Embedded SWR in an ethylene plant.....................................................72 Appendix G Embedded conventional furnace in an ethylene plant..........................73 Appendix H Experiment results .................................................................................75

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LIST OF FIGURES Figure 1-1 Demand/supply and Utilization balance of Ethylene [17] .........................11 Figure 1-2 Global Economics Growth forecast [17]....................................................12 Figure 1-3Ethylene production by feedstock’s [18] ....................................................13 Figure 1-4 Shock wave reactor system [10] ................................................................14 Figure 2-1 Equilibrium conversion in the dehydrogenation of the most important

lower alkanes at 1 bar as a function of temperature[29]......................................18 Figure 2-2 reaction rate of constants of various alkanes [22]......................................20 Figure 2-3 Scheme of shock wave reactor and corresponding temperature profile [13]

..............................................................................................................................21 Figure 2-4 Shock wave reactor as divided parts ..........................................................22 Figure 2-5 Discontinuities in one-dimensional flow ...................................................23 Figure 2-6 Principal arrangement of a cracking furnace [11]......................................25 Figure 3-1 Parity plot for the component methane and 1,3-butadiene (%) .................27 Figure 5-1Run length vs residence time for ethane cracking [11]...............................34 Figure 5-2 Minimum heating and cooling requirement with different outlet furnace

temperature. .........................................................................................................35 Figure 5-3 Yield ethylene and flow recycle ethane at different outlet furnace

temperature. .........................................................................................................35 Figure 5-4 By-product yield as function of furnace temperature. ...............................36 Figure 5-5 Furnace duty as function of furnace temperature.......................................36 Figure 5-6 Minimum heating and cooling requirement vs the steam temperature. Also

ethylene yield vs steam temperature. ...................................................................38 Figure 5-7 Ethane recycle at different steam temperatures .........................................39 Figure 5-8 Relation between steam temperature and byproduct yield ........................39 Figure 5-9 Minimum heating and cooling requirement + ethylene yield as function of

residence time ......................................................................................................40 Figure 5-10 Ethane recycle from separation section to SWR feed as function of

residence time of the SWR ..................................................................................40 Figure 5-11 By-products production as function of the residence time. The primary

axes is for the by-products except hydrogen. The secondary axes scale is for hydrogen. .............................................................................................................41

Figure 5-12 Minimum heating and cooling requirement + ethylene yield as function of Mach speed......................................................................................................41

Figure 5-13 Ethane recycle from separation section to SWR feed as function of Mach speed ....................................................................................................................42

Figure 5-14 By-products production as function of Mach speed. The primary axes scale is for the by-products except hydrogen. The secondary axes scale is for hydrogen. .............................................................................................................42

Figure 5-15 Minimum heating and cooling requirement + ethylene yield as function of pressure before shock ......................................................................................43

Figure 5-16 By-products production as function of pressure before shock. The primary axes scale is for the by-products except hydrogen. The secondary axes scale is for hydrogen. ...........................................................................................44

Figure 5-17 Ethane recycle from separation section to SWR feed as function of pressure before shock...........................................................................................44

Figure 5-18 SDF as function of minimum heating and cooling requirements and ethylene yield .......................................................................................................45

Figure 5-19 Ethane recycle as function of SDF...........................................................45

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Figure 5-20 By-products as function of SDF...............................................................46 Figure 5-21 Energy consumption SWR vs conventional furnace with pinch..............47 Figure 5-22 Energy consumption SWR vs conventional furnace without pinch.........48 Figure 5-23 energy consumption vs furnace temperature............................................48 Figure 5-24 Energy consumption without pinch for variation of the pressure before

shock ....................................................................................................................49 Figure A-7-1 Mixing distance as function of plenum pressure ratio [13] ...................59 Figure A-7-2 Throat nozzle determination ..................................................................60

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LIST OF TABLES Table 1-1 Raw materials for ethylene production .......................................................12 Table 2-1 Reaction scheme for ethane cracking [23] ..................................................19 Table 3-1 Fixed values and calculated values..............................................................26 Table 4-1Typical conversion data for ethane [9].........................................................28 Table 5-1 Yields from ethane cracking with a various residence time [11]. ...............33 Table 5-2 Fixed variables in order to determine the duty needed at different steam

temperatures.........................................................................................................38 Table 5-3 Fixed variables in order to determine the minimum heating and cooling

requirement at different residence time. ..............................................................40 Table 5-4 Fixed variables in order to determine the duty needed at different Mach

speed. ...................................................................................................................41 Table 5-5 Fixed variables in order to determine the duty needed at different pressure

before shock. ........................................................................................................43 Table 5-6 Fixed variables in order to determine the duty needed at different SDF.....45 Table 6-1 Input values in Matlab to determine sound power ......................................51 Table 6-2 Output parameters which are generated with SWR Matlab model. ............51 Table 6-3 Sound intensities at different mach speed...................................................52 Table 6-4 Mount type and properties [24] ...................................................................53

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1 Introduction Shock Wave Reactor (SWR) is a new concept in the chemical industry, which could substitute in the future the conventional furnace that is used in an ethylene plant. Nowadays for production of ethylene is done by a conventional furnace. This is done by steam cracking (pyrolysis). In steam cracking, hydrocarbons are thermally cracked in the presence of steam, yielding ethylene and some by-products. It is known that starting the pyrolysis has a high energy demand. This energy is used to increase the furnace temperature (18.8-20 MJ/kg ethylene) [23]. It is also known that the price of energy increases due to oil price. Obvious the energy price is coupled to the oil price. Ethylene is a bulk chemical, which is used to make glycol, vinyl’s, styrene’s, and polyethylene. The increase of the energy price, effects the price of ethylene. The main question in this report will be, ‘how will the SWR effect the energy consumption when it is embedded in an ethylene producing plant’. There are some literatures found that give the energy consumption.

1.1 Importance of ethylene Ethylene is a bulk chemical, which is used to make glycol, vinyl’s, styrene’s, and polyethylene. The applications of ethylene are numerous and ethylene derivatives are traded around the world. In the future ethylene will still used as bulk chemical for another processes. Ethane cracking is one of the oldest processes in the petrochemical industry. The cracking of ethane leads to ethylene and this is the largest-volume petrochemical produced worldwide. In 1998 total worldwide ethylene production capacity was

690 10⋅ tons, with an actual demand of ca. 680 10⋅ t/a [1], which has growth projections of 4.5 % per year worldwide for the period of 1996 to 2008 [2-4].

Figure 1-1 Demand/supply and Utilization balance of Ethylene [17]

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As it can see in figure 1-1, the demand of Ethylene is increasing. One of the reasons is that the economy of Asia is increasing especially of China as given in figure 1-2. Strong GDP (Gross Domestic Product) growth in major regions results in strong petrochemical demand growth. Figure 1-2 confirms the demand on ethane.

Figure 1-2 Global Economics Growth forecast [17]

1.1.1 Ethylene production from different feedstock’s Ethylene production is done by different feedstock’s namely:

• LPG, NGL (ethane, propane, butane) • Naphtha • Gas Oil • Refinery gas

Table 1-1 lists the percentage of ethylene produced worldwide from various feedstock’s for 1981 and 1992 [5]:

Table 1-1 Raw materials for ethylene production (as a percentage of total ethylene produced)

In 2003, the most used feedstock was also naphtha feedstock worldwide to produce ethylene. The second was ethane. In the United States, this was visa versa. As well as this 2 feedstock’s, propane, butane, gas oil and others like recycling stream in plants

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are used. Figure 1-3 shows the feedstock percentage used worldwide and in the United States to produce Ethylene [18].

Figure 1-3Ethylene production by feedstock’s [18]

A problem in the world is that raw materials run out in the future. This will lead in higher energy prices. So it is very important to think about the effects of in the future. SWR could be the answer of this problem if the SWR can reduce the energy consumption to produce ethylene. It will not be a best solution, but if the energy consumption decreases, the production of ethylene production can withstand this problem.

1.1.2 Gas Feeds [9] Because ethane is used is this ad feedstock, this feedstock will be the most important component used as feedstock in this report. Ethane is one of the more desirable feedstock’s for the production of ethylene. Ethane is usually one of the products derived from natural gas. Ethane can also be a product high can be produced from another plant. In a conventional furnace, ethane is usually cracked at a conversion level of 60%. Ethane feedstock has the advantage of high ethylene yield with a minimum production of by-products compared with another feedstock’s. In situations where by-products have no value other than as fuel, ethane is an ideal feedstock. Ethane feedstock for ethylene production has not been used on a worldwide basis because it is not available in sufficient quantity at every location and is used primarily in U.S. plant. Another gas feed that can be used as feedstock in an ethylene plant is propane. Propane is used in many U.S. ethylene plants as a feedstock and is normally cracked at a conversion level of 70-90% depending on the desired ratio of ethylene to propylene.

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1.2 Shock wave reactor To work efficient with the recourses the world has, a possibility is to use a SWR. The SWR is an option because:

• Could reduce the energy consumption • Increase in ethylene yield • No or less decoking needed • Reduction of the residence time during the shock

A Shock Wave Reactor could eliminate high-energy supplies though the wall and avoids coke formation. The initiating of the pyrolysis is done by a shock wave. Compared with the conventional method, shock waves are produced by the deceleration of a supersonic stream to subsonic velocity, results in an instantaneous increase in the temperature in the gas mixture. This temperate jump initiates the pyrolysis. After the pyrolysis, the mixture is rapidly quenched which results in a high yield ethylene. The advantage of the shock wave reactor is that the superheated steam and the hydrocarbon feedstock can be mixed at a temperature lower than the pyrolysis temperature. Rapid heating of the mixture enables a residence time in the pyrolysis section of only 5 to 1000 milliseconds. Figure 1-5 shows the shock wave system:

Figure 1-4 Shock wave reactor system [10]

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1.3 Objective research The main goal of the thesis is to embed the SWR into an ethylene plant. With the embedding of the SWR, some important information can be determined. It is important to pay attention in the,

• Ethylene selectivity and yield • Energy consumption of the whole plant • Reliability and accuracy of the SWR model • Safety of the SWR • Configuration of the separation section

Matter of minor importance is the environmental impact of the SWR. The SWR could produce a big amount of noise and can create a hazardous situation like ear damage. Obvious if the SWR produces a large amount of noise and vibration, this cannot be neglected. This report will include the next topics:

• SWR kinetics and thermodynamics • Ethylene plant with a SWR and a conventional furnace in AspenTech • Pinch analysis (Determination of the minimum heating and cooling

requirements) • Environmental impact (sound production) of the SWR

1.4 Research approach To determine some criteria’s, it is useful to compare the SWR with a conventional process. In conventional processes, a steam-cracking furnace is used. The basis purpose of this furnace is the same as the SWR, which is to crack hydrocarbons based on steam cracking. The comparison of the 2 different steam cracking will be built up in AspenTech. In AspenPinch the energy consumption will be determined. Based on the kinetics and thermodynamics of reference 21, a user model for the SWR must been developed. For the conventional furnace, this is not necessary. For this, a plug flow will be used with the data based on reference 9. The SWR model in Aspen must first be evaluated on the accuracy, reliability. If the accuracy of the SWR is bad, automatically the reliability is low. Having a separation section of the 2 plants, the feeds can be manipulated in order to:

• Separate the components • Purifying Ethylene • Recycle the ethane feed • Recycle the energy

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The configurations of the separation section must kept equal. Just the energy consumption can vary. Energy specification to produce ethylene Knowlen et al, [13] has made a design study, which has been carried out to assess the potential advantage of applying the SWR for commercial pyrolysis of ethylene using ethane as a feedstock. The specific energy consumption in conventional ethane pyrolysis is about 18-20 MJ per kg of ethylene produced. Using the SWR as the approach of this reference, the energy cost is estimated to be 13.7 MJ per kg of ethylene, a 15% reduction in energy consumption over that of conventional ethane cracking plants. Reference 14 claims a different opinion about the energy consumption. Instead of a reduction, there is an increase of the energy consumption with the SWR. The energy input of the design is 24.5 MJ per kg of ethylene produced. This is an increase of approximately 25% higher than the conventional process. The most energy investment here resides in the vaporization energy of the steam. These 2 references contradict each other. To obtain which reference is right, the embedding of the SWR is crucial.

1.5 Content chapters The following chapters are given more in detail about how to embed the SWR and what is used in order to make a proper SWR in Aspen. In chapter 2 the process chemistry with its thermodynamics and kinetics are explained. These properties are based on literature and a previous model that were made in Matlab by R.Bosma. In this chapter also the configuration of the SWR is given. Chapter 3 contains the validation of the SWR used in Aspen. A user model in Aspen has been made, which reflects the behavior of the SWR at some given conditions. Chapter 4 contains how the SWR is embedded in an ethylene plants. The separation section is also explained in this chapter with their configurations. With Aspen Pinch, the determination of the energy consumption is made. This is explained in chapter 5. This is very important because the energy consumption will conclude if this SWR economical favorable compared with a conventional furnace. Also the environmental impact of the SWR has been studied. It is known in the aviation industry, shock waves produce a lot of sound power. It can have a certain risk to the human health and environment. This is a complex problem because of the difficulties to monitor the sound behavior of this reactor. This research is given in chapter 6.

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In chapter 7, conclusions are made. The conclusion is based on ethylene yield, energy consumption and sound intensity.

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2 Process options and selection

2.1 Process chemistry Steam cracking yields a large variety of products, ranging from hydrogen to fuel oil. The product distribution depends on the feedstock and on the processing conditions. The most favorable conditions for the production of ethylene are high temperature, low hydrocarbon partial pressure and short residence time. These conditions are determined by thermodynamic and kinetic factors. In ethane cracking, more than 1 million reactions occur. It is almost impossible to use this kinetics to monitor the behavior of al the reaction. So the kinetics, published by Froment and Bischooff are used. To embed the SWR in an ethylene plant, the thermodynamic and kinetics parameters are needed to reflect the behavior of the SWR and the conventional furnaces.

2.1.1 Thermodynamics In a steam cracking plant, lower alkenes like ethylene, propylene and butadiene are mostly the desired products. Dehydrogenation of lower alkanes such as ethane, propane and butane forms the corresponding alkenes and hydrogen. Figure 2.1 shows the equilibrium for the hydrogenation of lower alkanes.

Figure 2-1 Equilibrium conversion in the dehydrogenation of the most important lower alkanes at 1 bar as a function of temperature[29].

Figure 2-1 shows at a thermodynamics viewpoint the reaction temperature should be higher if high conversion wanted. It is also favorable at low partial pressure of the alkanes. At every molecule converted, 2 molecules are formed. The best case is to set the pressure to vacuum, but in practice, steam dilution is used which has essentially the same effect. Figure 2-1 shows also that how smaller the alkanes, the higher the temperature has to be for a conversion.

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2.1.2 Kinetics In the reaction of ethane a lot of reactions occur. Normally there are more than 10.000.000 reactions in ethane pyrolysis. Because of the earlier research about the SWR, the reaction reference is taken from reference 12. In that research they are 7 different reactions, which are taken from Sundaram et al [12]. Table 2-1 shows the reactions with the kinetic model and properties,

Table 2-1 Reaction scheme for ethane cracking [23]

The whole calculation and determination of the pyrolysis section is given in appendix C. Here, al the steps and correlation are given how the reaction kinetics occurs. The major pathway to ethylene may be written as given in scheme 2-1.

Scheme 2-1 Mechanism of Ethane dehydrogenation [29]

It is found and generally agreed in reference 29, that the kinetics of cracking ethane is a free-radical mechanism. Scheme 2-1 gives the mechanism for the simplest feedstock (namely, ethane). In this scheme, the mechanism is simplified. This reaction is initiated by separation of the C-C bond in the ethane molecule. The result of this separation is 2 methyl radicals. The propagation step uses a methyl radical and an ethane molecule in the reaction to from methane and an ethyl radical.

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The ethyl radical then decompose into ethylene molecule and hydrogen radical. The hydrogen radical reacts with another ethane molecule to from hydrogen and an ethyl radical. Ethyl radical also can react with an ethylene molecule and will form butane radical. This is a secondary reaction, where ethylene reacts away into bigger molecules. The reaction of ethyl radical can also react with a methyl radical. This reaction will lead in formation of an ethylene molecule and a methane molecule. This step is a termination step because the radicals disappear and being saturated. Another termination step is the reaction of 2 hydrogen radical, where hydrogen can be formed. In practice, heavier hydrocarbons are trying to be avoided. In an ethylene-producing furnace, beside the low hydrocarbon partial pressure and high temperature, the residence in the pyrolysis section is short. This, because at a short residence time, the ethylene yield is high and heavier hydrocarbons yield is low due to domination of primary reaction. The first-order kinetics implies the rate of reaction of alkanes. Figure 2-2 shows rate constants of the cracking of a number of alkanes as a function of temperature.

Figure 2-2 reaction rate of constants of various alkanes [22]

How bigger the molecule, the bigger the reactivity of the molecule. It can be seen that ethane has the lowest reactivity constant. The reason of this is that ethane is more stable than other molecules. The reactivity increases with chain length. Ethane clearly shows the lowest reactivity. The first-order kinetics implies that the rate of the reaction increases with the increasing partial pressure of the reactants. But higher partial pressure also means more secondary reactions. The secondary reactions must be avoided in order to have a high ethylene yield. Bases on figure 2-2, the conversion must kept low in order to avoid secondary reactions. .

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2.2 Shock Wave Reactor

2.2.1 Process description The Shock Wave Reactor is a unique reactor, which can be, in the future, used as commercial purposes. It’s a concept, which is still in research. This concept applies gas dynamic processes to control the temperature history of the feedstock rather than heat transfer through tube walls [13]. A schematic profile is given in figure 2-3.

Figure 2-3 Scheme of shock wave reactor and corresponding temperature profile [13]

The reactor uses a hot gas carrier gas, which is expanded to supersonic velocity from reservoir temperature TCO to a temperature TC1 below the pyrolysis temperature. The gas is mixed with ethane feedstock to form a flow having a temperature T2. This temperature is the temperature when it can be measured if it moves with the fluid. A nozzle array is needed to accomplish the mixing in a reasonable distance. Pyrolysis is than instantaneously initiated by a stationary shock, held in the flow, raising the temperature to T3. The quench system can be used as a heat exchanger to increase the steam temperature, which is used as the hot fluid carrier gas.

2.2.2 Shock Wave Reactor configuration The configuration of the shock wave reactor can be divided into 5 parts. These parts are:

1. Expansion 2. Mixing 3. Shock wave 4. Pyrolysis 5. Quenching

Figure 2-4 shows how these parts are divided.

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Ethane feedstock

Hot fluidcarrier gas

Exp

ansi

on

Mix

ing

Sh o

ck

Pyr

olys

is

Que

nchi

ng

Figure 2-4 Shock wave reactor as divided parts

Expansion and mixing Steam, used as hot carrier fluid gas is expanded in order to increase the velocity of thie flow. Steam that enters the converging/diverging nozzle is preliminary preheated. This superheated steam has a temperature varying from 1300 till 1500 K. The flow of this steam is coupled to the flow of the hydrocarbon with a factor. This factor is called the steam dilution factor (SDF). This SDF is the molar mass of H2O divided by the molar mass of ethane. The purpose of accelerating the carrier fluid as it is heated is to increase the fluid’s enthalpy. The heated carrier fluid gas is conveyed in a channel from heater section to a nozzle section. This section acts like a venturi and expands the carrier fluid adiabatically to a higher velocity and a lower temperature. The temperature must be kept below the pyrolysis temperature after the deceleration of steam. Before ethane enters the SWR, it gets pressurized. Ethane also is preliminary preheated. Preheating the feedstock provides a higher stagnation enthalpy downstream in a mixing section than would be the case without feedstock preheating. Hydrocarbons used as feedstock are injected with a nozzle in order to accelerate the feedstock as it exits through openings, producing a high velocity. The velocity of the hydrocarbon, after injection, is lower than the mach speed of the carrier fluid. The difference between the velocities of the feedstock and carrier fluid streams in the mixing section leads to turbulent mixing of the feedstock and carrier fluid. As the mixing proceeds, the temperature of the streams approach an uniform temperature, intermediate between the initial stream temperatures at the entrance of the mixing section. The stream of feedstock and carrier fluid fully mixes in mixing section and leaves the section as a supersonic mixture with a common mach speed. In appendix A this determination is given.

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Shock wave A shock wave happens when velocity decreases. This means that kinetic energy is converted in perceptible energy. There are 3 laws that play a big role to determination of the shock wave namely the continuity, momentum and energy laws. The equations of continuity, momentum and energy for steady, adiabatic, frictionless flow must be satisfied by the 2 flow states in reference to figure 2-6. These flow states are before and after the shock. Appendix B contains how the calculation of the shock wave is done.

Figure 2-5 Discontinuities in one-dimensional flow

Quenching Quenching, also called ‘Transfer Line Exchanger’ or TLE, is done to cool down the hot cracked gases, which comes from the pyrolysis section. The cracked gases come from the pyrolysis section at 800-1300 ºC. The gases should be cooled instantaneously to preserve their composition. This is not so practical because the pyrolysis section of the SWR or the furnace used with the conventional way, are designed to minimize residence time of the hot gas in the adiabatic section between the pyrolysis section/furnace section outlet and quench-system cooling zone. Typically, residence time in this adiabatic zone should not exceed 10 % of the residence time in the pyrolysis section [11].

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2.3 Conventional steam cracking of ethane To compare the SWR with the conventional furnace, it is important to know how the conventional furnace works. The furnace has some advantages. One of the disadvantages of the furnace lay done in the energy consumption. It is important to know the behavior of the conventional furnace. To understand the behavior, the functioning of the conventional furnace must be known. In the world there are many ethylene plants, which are producing ethylene of ethane as feedstock. In these conventional plants, furnaces are used. There are many types of furnaces. An example is the Lummus furnace. This furnace has a capacity for full- range naphtha or atmospheric gas oils vary from 25.000 to 100.000 t/a. Another furnace that is been used is the millisecond furnace. This furnace is designed for shortest residence time and low hydrocarbon partial pressure. Ethane cracked with steam has some advantages compared with other hydrocarbons such as gas oils and naphtha’s. Advantages are:

• Less coke formation • Lower hydrocarbon partial pressure • Increase of the yield • Less coke formation

To have a maximum ethylene production, the furnace requires [11]:

• A highly saturated feedstock • High coil outlet temperature • Low hydrocarbon partial pressure • Short residence time in the radiant coil • Rapid quenching of the cracked gas

For the production of ethylene with ethane as feedstock, the coil inlet temperatures are in the range of 650°C-680°C. Typical conversion ranges of commercial furnaces are 60-70 %, with 67 % conversion being a typical figure for modern design [11]. Figure 1-4 shows a typical furnace, which is used to produce ethylene.

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Figure 2-6 Principal arrangement of a cracking furnace Feed= Hydrocarbon , BF= Boil Feed, HP steam = High pressure steam [11]

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3 Validation Shock Wave Reactor

3.1 Shock Waver Reactor in Matlab and ASPEN The modeling of the SWR in Matlab is already been done by R.Bosma [21]. This reference corresponds with the experiment by Hertzberg et al. 1994. To validate the model in Matlab and Aspen, some assumptions have been used. These assumptions are partial taken from Hertzberg et al [14] and some out of the report of R.Bosma. To validate the models, the output values of the models must be compared. The input values must be the same. Table 3-1 gives the input values and the calculated output values. This table is valid for the 2 models.

Input In the SWR Output Feed stream

Ethane

Feed stream Steam

Before Shock

After shock

After pyrolysis

T (K) Given Given Calculated Calculated Calculated P (bar) Given Given Given Calculated Calculated Mach

number Given Calculated Calculated

Residence time (s)

Given

Composition flow (mol/s)

Given Given Calculated Calculated

Table 3-1 Fixed values and calculated values

3.1.1 Variation of the parameters To validate the model in Aspen, some parameters are varied to compare the output values of the Aspen with Matlab. The deviation is said that it must be less than 1 % relative. The reason why there is a deviation in the 2 models is that, the integrator, which is used, differs. And there is a rounding off error. The deviation determining is done with the next parameters, which are varied.

• Steam temperature • Hydrocarbon temperature • Hydrocarbon pressure • The steam pressure • Hydrocarbon flow with a fixed SDF of 11.1

The input values for the parameters are given in appendix D and the output and deviation for the 2 models are given in appendix E. It can be seen that the output result after determining the deviation, is less than 1 %. Even for the pressure, temperature and some composition is the deviation better (below 0.1%). Just for the methane and 1,3-butadiene the deviation is higher than 0.1 %. As it can be seen in figure 3-1 the deviation for methane and 1,3-butadiene is

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almost on the line with a deviation of 0 %. There is no dot, which has an abrupt deviation. As said before, this relative difference has to do with the integrators and rounding off of the 2 modeling programs. For the general validation this value for the 2 components are acceptable.

Parity plot for methane and 1,3-Butadiene

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1015202530354045

0 10 20 30 40

Aspen output values

Mat

lab

outp

ut v

alue

s

Line with a deviationof 0 %

Deviation of Methane(%)

Deviation of 1,3-Butadiene (%)

Figure 3-1 Parity plot for the component methane and 1,3-butadiene (%)

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4 Modeling of the SWR and conventional furnace reactor in Aspen

4.1 Objective To have a view of the energy consumption of an ethylene plant with a SWR, it is important to compare it with another way to produce ethylene. For this, a comparison is made with a conventional ethylene plant where a conventional furnace is used to crack ethane. There is an important rule for this comparison. The only thing that must change is the reactor and the furnace. After the reactor section, the configuration must be equal. The heaters and coolers must work at the same conditions. That is also valid for the 3 distillation columns, except the energy duty utilities may vary. This due to the changing of the feed composition. If the feed contains higher ethylene, the distillation column needs more energy to purify the ethylene in the distillation column. The plant with a SWR is given in appendix F and for the conventional furnace in G.

4.2 Ethylene plant with a conventional furnace To model the furnace in AspenTech, a plug flow reactor is used. This plug-flow model is capable to enter the rate-controlled reactions based on kinetics. This kinetics are taken from reference 21. The operating conditions temperature is taken constant at specified reactor temperature. The reactor is a multitube reactor and has approximately 149 tubes. The tube dimensions have a length of 10m and a diameter of 0.1 m. The valid phase is vapor, because at high temperature the composition is fully vapor. The dimensions of the conventional furnace are based on the conversion ethane as given in table 4-1.

Ethane conversion per

pass (%)

55.0 60.0

Composition

(Mole %) Feed Furnace

effluent Feed Furnace

effluent H2 32.5 32.7

CH4 5.2 6.3 C2H2 0.2 0.2 C2H4 2.0 31.9 2.0 33.8 C2H6 96.7 28.7 95.2 24.9 C3H6 1.3 0.5 2.2 1.0 C3H8 0.3 0.6 0.2 C4 0.4 0.4

C5+ 0.3 0.5 Total 100 100 100 100

Table 4-1Typical conversion data for ethane [9]

29

Based on this conversion, the furnace is configured such that the composition after the furnace is approximately the same as the result given in this table. Now, it is possible to vary some parameters and determine what the impact is on the energy consumption of these parameters. Temperature will have a major impact on the energy consumption and ethylene selectivity. For the whole plant in Aspen a tear tolerance of 0.00001 is taken. This means that the output in the simulation are accurate.

4.3 Ethylene plant with a SWR After the validation of the SWR, the SWR is built up in AspenTech. The only difference of this simulation, compared with the conventional furnace as explained in 4.2, is the substitution of the furnace with the SWR. Because the SWR is a user model, this model is made in a FORTRAN language, which communicates with Aspen. Aspen gives some parameters to this model. After calculations with the given parameters, this used model gives the calculated parameters back to Aspen. This repeats till the given tear is acceptable. The fixed parameters, which must be defined in the SWR user model, are,

• Mach speed (-) • Pressure before shock (Bar) • Cone angle (°) • Residence time in pyrolysis section (s) • Maximum step size

The SWR user model has 2 feed entrances. The first one is the hydrocarbon feed and the second one is the steam feed. Before the steam enters the SWR user model, this stream is heated up to a defined temperature. The steam flow is coupled to a SDF of 11.1. The hydrocarbon feed is also preheated to a certain temperature. After the pretreatment of these 2 streams, it enters the SWR user model. With the defined parameters, the SWR will calculate the compound properties and some properties in the SWR. The SWR properties, which are calculated, are:

• Temperature before shock (K) • Diameter of mixing section (m) • Post shock temperature (K) • Post shock mach speed • Post shock pressure (bar)

After the calculation the output stream of the SWR will head for the separation section where ethylene, ethane and the other by-products will be separated. The ethane will be recycled to the SWR. This process will repeat till a tear tolerance of 0.0001 is achieved.

30

4.4 Configuration utilities used for separation After the furnace, the composition must be rapidly cooled. This is done by a transfer line exchanger (TLE). The function of this TLE is that, it must decrease the temperature under the reaction temperature. This means that the temperature must decrease below 875 K in just few milliseconds. Under this temperature, ethane reactions and secondary reaction will stop. Water removal (water-Quench column) and molecular sieve dryer After cooling the stream from the reactor/furnace, this stream is routed to the water quench column in which the cracked gas is cooled near ambient temperature by contacting it with a large stream of circulating quench water. In this cooling step most of the dilution steam and heavy gasoline are condensed and collected at the bottom of the vessel. After separation, the water stream is used to produce dilution steam that is used by the conventional furnace or the SWR. After treating the stream with the water quench column, the vapor-cracked gas is treated with a sieve dryer [27]. Moisture must be removed before fractionation to prevent formation of hydrates and ice. Typically, this is accomplished by chilling and by adsorption on molecular sieves. Older plants also used absorption by a glycol scrubbing system or adsorption on alumina. Drying is arranged before the first fractionation step, typically after the last compression stage. Before feeding the compressor effluent to the molecular sieve dryer it is cooled in a water cooler and subsequently by propane refrigerant. A temperature of 15 ºC upstream of the dryer is desirable for removing as much water as possible to reduce load on the dryers. Scrubber (acetylene hydrogenation) A scrubber is used to take out the acetylene out of the stream. The removal of acetylene from ethylene producing processes if of particular concern because of the difficulty in removing this compound. A number of processes exist for the removal of acetylene from ethylene producing processes. One of such processes is the front-end de-propanizer acetylene removal unit. Front-end de-propanizer typically employs a Pd catalyst acetylene hydrogenation system located on the front-end (of the distillation train) de-propanizer overhead stream. This unit hydrogenates all the acetylene and the most of the methyl acetylene/propadiene on a propane and lighter stream. Distillation columns As explained above, there are 3 distillation columns used. The first column, which has been entered by the stream coming from the quench, is the de-propanizer. This column separates C3

+. The pressure of this column is set to 19 bar with a recovery of 0.9999. This pressure is based on the boiling points. In AspenSplit, a quaternary diagram is made. Unfortunately, 4 components can be used in stead of 7. The 4 components which are used are ethane, ethylene, propylene and propane. The reason

31

of this choice is that the depropanizer must separate C3 + hydrocarbons. Propylene and

propane are the biggest molecules of the 4 components, so propylene and propane are the liquid products of the mixtures. There is also 1,3-butadiene in the mixture. Because this molecule is the biggest in the mixture, these components will also leave the distillation column in liquid state. The boiling points are respectively -7.3 ºC, -28,9 ºC, 48.7 ºC and 57.0 ºC. With these boiling points, the distillate temperature is -22,6 ºC and the reboiler temperature 42.7 ºC. At these conditions, the given recovery of the distillate is achieved. Before the stream enters the de-propanizer as feed, the stream gets compressed and cooled. The stream is set to 20 bar and -40 ºC. The second distillation column is the de-methanizer column. This column separates the liquid ethylene and ethane of the vapor impurities like methane and hydrogen. The pressure is set to 30 bar with a recovery fraction of 0.9999 methane. The pressure is also here based on quaternary diagram. Here hydrogen and methane is separated of ethane and ethylene. The boiling temperatures of these are respectively -240 ºC, -96.2 ºC, 9.5 ºC and -13.4 ºC. The distillate temperature is set to approximately -134 ºC and the reboiler temperature is -13.7 ºC. The liquid ethane and ethylene is been separated of the methane and hydrogen. Before the stream enters this distillation column, the hydrocarbon stream is pretreated to reduce the hydrogen and methane concentration in this stream. Before the stream enters the de-methanizer, the feed which comes from the scrubber, gets pretreated. The reason of this pretreating is to improve his performance. With this pretreating configuration, the de-methanizer won’t need to be big, energy slurping and to have a large amount of scales. What is done at the pretreating is to cool the stream to -70 ºC that comes from the scrubber. After cooling a simple flash drum is separating the liquid phase of the vapor phase. The liquid phase here has a major mole fraction of ethane and ethylene. The vapor phase is cooled down to -120 ºC. So more ethane and ethylene is now in liquid phase. This is also treated in a flash drum. The vapor phase of this flash drum is fed into a compressor and again in a cooler. The pressure is set to 27.6 and -140 ºC. At these conditions, more ethane and ethylene can be liquefied. This stream enters a flash drum an again liquid phase is separated of the vapor phase. Al the liquid phases are connected and sent to the de-methanizer. Now the de-methanizer can purify the ethane and ethylene. The vapor stream of the de-methanizer heads to the hydrogen purification section. The last distillation column, which is used, is the de-ethanizer. This distillation column separated and purifies the gaseous ethylene of the liquid ethane. The pressure here is set to 19 bar with a recovery fraction of 0.9999 ethylene. Here the pressure is based on binary diagram. Ethane and ethylene has a boiling temperature of -9.3 ºC and -30.7 ºC respectively. Ethane is recycled to the furnace. With this configuration, an ethylene purity of at least 99.98% is achieved. The pressures of the distillation columns are based on boiling temperatures. In the de-propanizer, the boiling gap between ethane and propane is highest at 19 bar. So distillation of the products is the best at this pressure. For the de-methanizer and de-ethanizer the pressure is 30 and 19 bar respectively.

32

The refluxes of the columns are at every experiment different. This due to changing in the composition fraction of the inlet stream. No azeotropes are present so this means that the differences of boiling temperature of the components are high. For all distillation columns, shortcut distillate designs are used. This shortcut is using the Winn-Underwood-Gilliland method (DSTWU). This approach uses Winn-Underwood-Gilliland shortcut design calculations. It is designed for a single feed and 2 product distillation column. • Winn - estimates minimum stages • Underwood - estimates minimum Reflux Ratio (RR) • Gilliland - relates actual number of stages and RR In order to use this option the specification of the of the light and heavy keys must be given. DSTWU calculates the minimum reflux ratio and minimum number of theoretical plates for the given specified recovery. It then calculates the actual reflux ratio for the specified number of stages, or the actual number of stages for the specified reflux ratio, depending on which is entered. It also determines the optimal feed location and reboiler and condenser duties. Hydrogen purification The ethylene process also produce hydrogen. Hydrogen is an important bulk chemistry that can be used in other plant or processes. So hydrogen can be used or sold as product. The purity of hydrogen is important so, at hydrogen must be purified. The streams that comes from the methane pretreating and de-methanizer, contains hydrogen. Before these 2 streams are mixed, the stream, coming from the pretreating, is been cooled down to 200 ºC. After cooling, the liquid phase is separated and mixed with the stream coming from the de-methanizer. After mixing, the stream temperature is held to 200 ºC and headed to a flash drum. The liquid phase here is methane and vapor is hydrogen. With this technique, a hydrogen purification of at least 98.5 can achieved.

33

5 Energy consumption To obtain the main goal of this research, the minimum heating and cooling requirement of the cracking reactors are determined. But how is this energy requirement influenced by the SWR or plant with a conventional furnace? This is a question where the conclusion will be based on. The conclusion if the SWR needs less energy to have the same or more ethylene. To determine this, the temperature of the steam in the SWR and the temperature of the furnace in a conventional plant play a big role. How will the ethane conversion affects the ethylene yield and selectivity and what will happen with the byproduct yield? Another subject, which must be investigated, is what the energy consumption will be in order to separate these components from each other. In chapter 5.1 the minimum heating and cooling requirement to produce ethylene is determined for the conventional plant. Here the furnace temperature has been varied. For the SWR this is given in chapter 5.2. In appendix H, the calculations are given for the determining the duty for all experiments. The composition curve is also given in this appendix. The composition curves are made with Aspen Pinch. This application uses the parameters and values, which are generated in Aspen Tech.

5.1 Energy consumption with a conventional furnace The first determination is what the effect is on the energy requirement with variation the furnace temperature. The furnace has a fix configuration. In the article of Zimmerman [11], the residence time varies from 0.1 till 0.5 seconds. Short residence time has some advantage’s and some disadvantages. As given in table 5-1, there is a slight increase in yield at short residence time.

Table 5-1 Yields from ethane cracking with a various residence time [11].

34

It is generally agreed that the residence time affect the run length of the cracking system. Figure 5-1 shows the effect of the residence as function of the run length in days. With this information, the assumption is that the residence time could not be low. Lower residence time means more turnaround needed to decoke the coils in the furnace.

Figure 5-1Run length vs residence time for ethane cracking [11].

The relationship between residence time, conversion and reaction temperature for a first order mechanism in a plug flow tubular reactor is represented by

0

1ln exp

1 ( )

EA dt

RT t

τ

ζ −= −

∫ 5.1

where ζ is the conversion, τ the residence time in seconds, A the frequency factor in s-1, E the activation energy in J/mol, T the temperature and R the universal gas constant in 1( )J mol K −⋅ ⋅ . Equation 5.1 claims at higher temperature, the higher the conversion and so the residence time must be low. The residence time cannot be small (less then 0.2 seconds) due to short run length. Unfortunately, it is unknown where figure 5-1 is based on. It just an indication. This figure is taken from reference 11, but this reference does not say anything about the condition and how this plot is made.

5.1.1 Variation of the furnace temperature The temperature of the furnace has an impact on the conversion, ethylene yield and residence time. Typical furnace inlet temperatures for ethane as feedstock are 923-953 K depending on the material processed [11]. Typical outlet temperatures are 1073-1148 K. In order to determine the minimum heating and cooling requirement, the temperature is varied between 1043-1153 K with an interval of 10 K. Below a temperature of 1043 K the Aspen model gave errors. This due to the low ethane conversion. This leads to enormous ethane recycle and to separate and purify the ethylene from the ethane is in practice not achievable. The conditions of the hydrocarbon are the same, which are used in reference 21. This hydrocarbon flow used as feedstock enters the furnace at 923 K and has a pressure of 2.4 bar. The composition of the hydrocarbon feed which enters the plant contains 310 mol/s ethane, 3.1 mol/s ethylene and 2.48 mol/s of propylene.

35

For the whole plant, the temperature has also an impact on the energy consumption. Especially for the distillation columns and heat exchangers. In figure 5-2 the energy needed for whole the plant is given when varying the furnace temperature without bleeding the recycle ethane. This means, al the recycle ethane coming from the ethane/ethylene separation section will mix with the ethane feed and flow into the furnace. In appendix H the tables are given which are used to determine the minimum heating and cooling requirement for the given furnace temperature.

Figure 5-2 Minimum heating and cooling requirement with different outlet furnace temperature.

As it can be seen in figure 5-2, at high furnace outlet temperature, the minimum heating and cooling decreases. At higher furnace outlet temperature, the residence time has a maximum. After this residence time maximum, the minimum heating and cooling requirement stabilizes. One of the reasons of this behavior is that the ethane conversion is very high at high furnace temperatures. The recycle of ethane and ethylene yield in mol/s are given in figure 5-3

Figure 5-3 Yield ethylene (mol/s) and flow recycle ethane (mol/s) at different outlet furnace temperature.

Minimum heating and cooling requerement

0

20

40

60

80

100

120

1000 1050 1100 1150 1200

Furnace temperature (K)

Min

imum

nee

ded

duty

(M

W)

00,050,10,150,20,250,30,350,40,450,5

Res

iden

ce ti

me

(s)

Hot

Cold

residence time

Yield ethylene and ethane recycle at different furnace outlet temperature (ºC)

305,5

306

306,5

307

307,5

308

308,5

1000 1050 1100 1150 1200

Furnace outlet temperature (ºC)

Yie

ld E

thyl

ene

(mol

/s)

0

500

1000

1500

2000

2500

Flo

w r

ecyc

le

etha

ne (

mol

/s)

Ethylene (mol/s)

Ethane recycle

36

In figure 5-3, the ethane recycle flow is approximately 0 at higher furnace temperatures. This means there is almost no ethane recycled back to the furnace. The ethylene yield has a maximum at approximately 1113 K. At this temperature the residence time is 0.457 seconds. Higher furnace temperatures lead to overcracking. The ethylene yield decreases if the furnace temperature is higher than 1113 K. Temperatures higher than 1113 K also gives a decrease in the residence time. After this temperature, the ethylene yield slightly decreases due to secondary reactions. A slight increase in propane production is observed. Figure 5-4 shows the yield byproduct at different furnace temperatures.

Figure 5-4 By-product yield as function of furnace temperature.

Normally the furnace duty increases if the temperature of the furnace increases. As given in figure 5-5, this is semi valid. At low furnace temperature, the furnace duty is the highest. This due to the ethane recycles. Because of the low furnace temperature, the conversion of ethane is low. So the recycle of ethane is very high and to heat up this flow, the energy input requirement is higher compared when the conversion of ethane is higher.

Figure 5-5 Furnace duty as function of furnace temperature

By-product yield vs furnace temperature

0

1

2

3

4

5

6

1043

1063

1083

1103

1123

1143


Yie

ld (

mol

/s)

301301.5302302.5303303.5304304.5305305.5

Yie

ld H

ydro

gen

(mol

/s)

Methane

Acetylene

propylene

propane

Hydrogen

Furnace duty vs temperature

0102030405060708090

1043

1053

1063

1073

1083

1093

1103

1113

1123

1133

1143

1153


Fur

nace

dut

y (M

W)

Furnace duty

37

5.2 Energy consumption with a SWR To investigate the energy consumption of the SWR plant, some parameters must been varied. This variation of the parameters will indicate the behavior of the SWR embedded in an ethylene plant. The parameters, which are varied, are,

• Steam temperature (K) • Residence time in the pyrolysis section (s) • Mach speed (-) • Pressure before shock (bar) • SDF (-)

These parameters will give some output. These important outputs are,

• Minimum heating and cooling requirement (kW) (calculated with Aspen Pinch)

• Ethylene yield (mol/s) • Flow ethane recycle (mol/s) • Yield byproducts (mol/s)

The minimum heating and cooling requirement is needed to determine the energy consumption of the whole plant. It is also known that variation of the parameters will also affect the ethylene selectivity, and byproduct yield. If the parameter affects the ethane conversion, the selectivity of ethylene and byproducts will automatically be affected. This will result in difference minimum heating and cooling requirement. After some test of the SWR in Aspen, the SWR was instable. The reason of this behavior is the fluctuation of the ethane recycling. This fluctuating leads to fluctuation in the hydrocarbon flow, which enters the SWR. The tear tolerance also fluctuates as result of this behavior. A second user model is made which is correcting the steam flow (SDF) that enters the SWR. This process of correction is given in figure 5-1. In this user model a fixed SDF is used. In this user model, the SDF can be given. On the hand of this SDF, the SWR steam flow will have continu the corrected steam flow. So when the total (Hydrocarbon feed + Ethane recycle feed flow) hydrocarbon feed is changing, the steam flow also changing with the given SDF.

Scheme 5-1 How the steam factor is corrected with the fluctuation of the ethane recycle.

SWRCorrection SDF

Separationprocess

Water tank

Water output

Corrected steam flow

Hydrocarbon flow as feedstock

Hydrocarbon Feed

Ethane recycle

38

5.2.1 Variation of the SWR steam temperature The variation of the steam temperatures has an impact on the minimum heating and cooling requirement to produce ethylene. These experiments consist in varying the steam temperature. Table 5-2 shows, which fix variables, are used in order to determine the energy requirement of the whole plant. The steam temperature is varied between 1100-1600 K with an interval of 50 K.

Variables Mach speed

Pressure before shock (bar)

Cone angle (º)

Residence time at pyrolysis (s)

Steam pressure (bar)

SDF (-)

Hydrocarbon temperature (K)

Hydrocarbon pressure (bar)

2.4 1.4 5 0.1 15 11.1 400 3

Table 5-2 Fixed variables in order to determine the duty needed at different steam temperatures

The result for the minimum heating and cooling requirement are given in figure 5-6. In this figure, the ethylene yield is given.

Figure 5-6 Minimum heating and cooling requirement vs the steam temperature. Also ethylene yield vs steam temperature.

At the first sight, this might be odd but it is not. At higher steam temperatures, ethylene yield decreases but the minimum heating and cooling also decreases. This has to do with the recycle of the ethane. At low steam temperature, the conversion of ethane is low so the ethane flow heading to the SWR increases. At low steam temperature, the separations of the components need more energy. At higher steam temperature, the conversion is higher so less ethane will be recycled (figure 5-7). At higher SWR steam temperature, the recycle of the ethane flow is heading to 0.

Minimum heating + cooling requirements and ethylene yield at different steam temperatures

0

1000

2000

3000

4000

5000

6000

11001150120012501300135014001450150015501600

Steam temperature (K)

Dut

y (M

W)

050100150200250300350

Eth

ylen

e yi

eld

(mol

/s)

Minimum heating

Minimum cooling

Ethylene

39

Figure 5-7 Ethane recycle at different steam temperatures

So less energy is needed to separate the ethane of the methane and ethylene because at higher steam temperatures the conversion is higher. At higher temperature less ethylene is produced. This means overcracking dominates. This behavior results in higher methane production as given in figure 5-8.

Figure 5-8 Relation between steam temperature and byproduct yield

5.2.2 Variation of the residence time Another parameter that has an impact on the ethylene yield is the residence time in the pyrolysis section. During the shock a temperature jump is achieved. Lower residence time means primary reactions dominates. Residence time has also an impact on the hydrocarbon outlet temperature. At low residence time, not al the kinetic energy is converted into feasible energy. At higher residence time, this kinetic energy decreases. At this chapter, the investigation of the residence time is done in order to determine the influence of the minimum heating and cooling requirements and also ethylene yield and selectivity. For this investigation the fixed variables in table 5-3 are used. The residence time is varied here from 0.005 seconds till 0.115 seconds.

Ethane recycle

02000400060008000

1000012000140001600018000

1100

1150

1200

1250

1300

1350

1400

1450

1500

1550

1600


Flo

w r

ecyc

le (

mol

/s)

Ethane recycle

Yield byproducts vs steam temperature

0

10

20

30

40

50

60

70

1100 1150 1200 1250 1300 1350 1400 1450 1500 1550 1600


Yie

ld (

mol

/s)

Methane

Acetylene

Propylene

Propane

40

Variables Mach

speed Pressure before shock (bar)

Cone angle (º)



SDF (-)



2.1 1.4 5 1400 15 11.1 400 3

Table 5-3 Fixed variables in order to determine the minimum heating and cooling requirement at different residence time.

As it can be seen in table 5-3 a steam temperature of 1400 Kevin is used. The reason of this choice is that at lower residence time, the pyrolysis outlet temperature must not decrease below the crossover temperature. This crossover temperature is the initiating temperature. Figure 5-9 shows the how the relation is between minimum heating and cooling requirement and residence time.

Figure 5-9 Minimum heating and cooling requirement + ethylene yield as function of residence time

It can be seen in figure 5-9, the residence time has also a big impact on the minimum heating and cooling. As the residence time in the pyrolysis section increases, the minimum duty and the ethylene yield decreases. The reason why the minimum heating and cooling requirements decreases, is that at higher residence time, the ethane conversion is higher, so less ethane is been recycled. Also here overcracking dominates. So less ethylene has to be purified. In figure 5-10 the function of residence time vs ethane recycling is given. In figure 5-9, the ethylene yield decreases at higher residence time. This has to do with the secondary reactions. At higher residence time, ethylene selectivity decreases due to secondary reactions.

Figure 5-10 Ethane recycle from separation section to SWR feed as function of residence time of the SWR

Ethane recycle

0

500

1000

1500

0,005 0,009 0,015 0,03 0,045 0,055 0,07 0,085 0,095 0,11

Residence time (s)

Eth

ane

recy

cle

feed

to

SW

R (

mol

/s)

Ethane recycle

Residence time vs minimum heating and cooling requerments and ethylene yield

0

200

400

600

800

1000

0,01 0,01 0,02 0,03 0,05 0,06 0,07 0,09 0,1 0,11

Residence time (sec)

Dut

y (M

W)

265270275280285290295300305

Eth

ylen

e Y

ield

(m

ol/s

)

Hot

Cold

Ethylene

41

Especially the byproduct methane and 1,3-butadiene (figure 5-11) production increases.

Figure 5-11 By-products production as function of the residence time. The primary axes is for the by-products except hydrogen. The secondary axes scale is for hydrogen.

5.2.3 Variation of the SWR Mach speed Another variable, which also affects the minimum heating and cooling, is the velocity. Table 5-4 shows the fixed variables that are used in the configuration of the SWR. The Mach speed is varied from 1.6 till 2.2.

Variables Residence time (s)


Cone angle (º)



SDF Hydrocarbon temperature (K)


0.1 1.4 5 1400 15 11.1 400 3

Table 5-4 Fixed variables in order to determine the duty needed at different Mach speed.

At higher Mach speed, the minimum heating and cooling requirements decreases. This is given in figure 5-12. Also here, it can be seen in figure 5-12, at higher Mach speed, the ethylene yield decreases. The ethylene yield increase relatively fast. This has mainly to do with overcracking.

Figure 5-12 Minimum heating and cooling requirement + ethylene yield as function of Mach speed

Mach speed vs minimum heating and cooling requirements and ethylene yield

050

100150200250300350400

1.6 1.7 1.8 1.9 2 2.1 2.2

Mach speed (-)

Dut

y (M

W)

275

280

285

290

295

Eth

ylen

e Y

ield

(m

ol/s

) Hot

Cold

Ethylene (mol/s)

Byproduct production as function of residence time

290292294296298300302

0.00

50.

015

0.04

50.

070.

095

Residence time (s)

Hyd

roge

n yi

eld

(mol

/s)

0

5

10

15

20

25

Yie

ld b

ypro

duct

s (m

ol/s

) Hydrogen

Methane

Acetylene

propylene

propane

1,3-butadiene

42

The ethane recycle is almost stable so, ethane flow has here no impact on the minimum heating and cooling requirement as a whole plant (figure 5-13).

Figure 5-13 Ethane recycle from separation section to SWR feed as function of Mach speed

As given in figure 5-14, 1,3-butadiene and methane yield increases at higher Mach speed. At lower Mach speed, the ethylene yield is highest. But lower Mach speed cannot be achieved. Because at lower Mach speed, the temperature of steam is higher than the initiating temperature. This means, when the hydrocarbon feed is been mixed with the steam, the pyrolysis will start before it enters the shock.

Figure 5-14 By-products production as function of Mach speed. The primary axes scale is for the by-products except hydrogen. The secondary axes scale is for hydrogen.

Byproduct production as function of Mach speed

0

5

10

15

20

25

1.6 1.7 1.8 1.9 2 2.1 2.2

Mach speed (-)

Yie

ld b

ypro

duct

s (m

ol/s

)

292

293

294

295

296

297

298

299

300

Hyd

roge

n yi

els

(mol

/s)

Methane

Acetylene

propylene

propane

1,3-butadiene

Hydrogen

Ethane recycle

200210220230240250260270280290300

1.6 1.7 1.8 1.9 2 2.1 2.2

Mach speed (-)

Eth

ane

recy

cle

feed

to S

WR

(m

ol/s

)

Ethane recycle

43

5.2.4 Variation of the SWR pressure before shock The pressure before shock is a parameter, which is used, in the mass, momentum and energy balance. How higher the pressure before shock, the higher the pressure after the shock. This will have an impact on the conversion of ethane. At lower pressure before shock, the selectivity of ethylene is higher. At higher pressure before shock, the selectivity is decreasing. This is given in figure 5-15. Table 5-5 shows the fixed variables that are used in the configuration of the SWR. The pressure before shock is set to 1.1-1.8 bar.


Mach speed

Cone angle (º)



SDF (-)



0.1 2.1 5 1400 15 11.1 400 3

Table 5-5 Fixed variables in order to determine the duty needed at different pressure before shock.

Figure 5-15 Minimum heating and cooling requirement + ethylene yield as function of pressure before shock

The reason of this decrease of the selectivity of ethylene is that more byproducts are produced. This means, also at higher pressure before shock, overcracking dominates. Hydrogen decreases but the rest of the byproducts increase at higher pressure before shock. The byproducts production as function pressure before shock is given in figure 5-16.

Pressure before shock vs minimum heating and cooling requerments and ethylene yield

050

100150200250300350400

1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8


Dut

y (M

W)

265

270

275

280

285

290

Eth

ylen

e Y

ield

(m

ol/s

) Hot

Cold

Ethylene

44

Figure 5-16 By-products production as function of pressure before shock. The primary axes scale is for the by-products except hydrogen. The secondary axes scale is for

hydrogen.

In figure 5-15 is also shown that the minimum heating and cooling duty needed decreases at higher pressure before shock. At other parameters, which are varied before such as steam temperature, residence time and Mach speed, the reason of the decrease was that the ethane recycles decreases, which resulted at lower hydrocarbon flow, which enters the SWR. For the pressure before shock, this is not the case. As shown in figure 5-17, the ethane recycle has a stable flow.

Figure 5-17 Ethane recycle from separation section to SWR feed as function of pressure before shock

In figure 5-17 the ethane recycle doesn’t change. It is in a range of approximately 268-265 mol/s of ethane. So one of the reasons of this strange behavior can be that at higher pressure before shock, the ethane conversion stabilizes, but on the other hand the ethylene selectivity decreases. So more by-products are formed and the separation of this is easier when ethylene in proportion to by-products is low. This hypothesis can also be valid for the ethylene plant with other parameters, which are varied. Another hypothesis is that at higher pressure before shock the ethylene selectivity decreases and lower ethylene flow means less energy needed to separate the ethylene from ethane.

Byproduct production as function of pressure before shock

0

5

10

15

20

25

30

1,1 1,2 1,3 1,4 1,5 1,6 1,7 1,8


Yie

ld b

ypro

duct

s (m

ol/s

)

290291292293294295296297298

Hyd

roge

n yi

els

(mol

/s)

Methane

Acetylene

propylene

propane

1,3-butadiene

Hydrogen

Ethane recycle (mol/s)

200210220230240250260270280290300

1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8


Eth

ane

recy

cle

feed

to S

WR

(m

ol/s

)

Ethane recycle

45

5.2.5 Variation of the SWR SDF The steam dilution factor is a big key in the energy duty of the SWR. Al the experiments above, are made with a SDF of 11.1. This SDF comes from the report of R.Bosma [21]. Heating up the steam with a given factor will influence the energy consumption of the SWR. Experiments are made varying the SDF from 6 to 10.5 with an interval of 0.5. Figure 5-18 below gives the energy duty needed and the ethylene yield vs the SDF and table 5-6 gives the fixed variables that are used in the configuration of the SWR.


Mach speed

Cone angle (º)





0.1 2.1 5 1400 15 400 3

Table 5-6 Fixed variables in order to determine the duty needed at different SDF.

Figure 5-18 SDF as function of minimum heating and cooling requirements and ethylene yield

It can be seen in figure 5-18, at higher SDF, the minimum heating and cooling decrease. On the other hand, the ethylene has an optimum (approximately at SDF of 8). The reason of this behavior is the duty needed in the SWR and the separation section. At low SDF, less energy is needed to heat up the steam. But the conversion is lower. This means that more ethylene is recycled. And to separate the components, the separation section needs more energy. Figure 5-19 shows this ethane recycle flow.

Figure 5-19 Ethane recycle as function of SDF

SDF vs minimum heating and cooling requerments and ethylene yield

0

400

800

1200

1600

6 6. 7 7. 8 8. 9 9. 1010

SDF (-)

Dut

y (M

W)

290

300

310

Eth

ylen

e Y

ield

(m

ol/s

)

Hot

Cold

Ethylene

Ethane recycle (mol/s)

0

1000

2000

3000

4000

5000

6000

6 7 8 9 10

SDF (-)

Eth

ane

recy

cle

feed

to S

WR

(m

ol/s

)

Ethane recycle

46

At higher SDF, the recycle is lower due to high conversion. At higher SDF also more by-products are produced due to higher conversion of the ethane. So overcracking dominates at approximately at SDF of 8. This is given in figure 5-20.

Figure 5-20 By-products as function of SDF

As it can be seen in figure 5-20, especially methane yield increases at higher SDF. So at lower SDF the separation section needs a lot of energy to separate the components. At higher SDF, less energy is needed to separate the components. But on the other side, the SWR needs more energy to heat up the steam and the selectivity of ethylene decreases.

Byproduct production as function of SDF

295

296

297

298

299

300

301

6

6.5 7

7.5 8

8.5 9

9.5 10

10.5

SDF (-)

Hyd

roge

n yi

eld

(mol

/s)

0

2

4

6

8

10

12

Yie

ld b

ypro

duct

s (m

ol/s

)

Hydrogen

Methane

Acetylene

propylene

propane

1,3-butadiene

47

5.2.6 Comparison energy consumption SWR and furnace In chapter 1.5.2 previous, 2 articles (reference 13 and 14) have a contradiction results in the consumption of the energy consumption of the SWR. Reference 13 claims that the energy consumption decreases with the SWR and reference 14 said there is an increase in the energy consumption on the SWR. In this research, this is also investigated. The energy consumption in MJ/kg ethylene is important and will conclude which reference is right. In the previous sub-chapter the minimum heating and cooling requirements is determined for different parameters. The variation gave different ethylene yields. Now this ethylene yield is given in figure 5-21 with their minimum heating and cooling requirement. This minimum heating and cooling requirement is partial. Here pinch is made. This means that the minimum heating and cooling duty is used to determine this. Figure 5-22 shows the plot of the energy consumption without pinch. This is one for the different parameter experiment for the SWR and also the energy consumption of the conventional furnace is given. The energy consumption is based on theoretical results, generated in Aspen application. Some losses are not taken into account. Losses like heat loss and pressure drop. The minimum heating and cooling requirement of the whole plant is higher but how high cannot be said due to ignorance of losses. This part of the research is just an indication of the behavior of the SWR and conventional furnace used in an ethylene plant. As is can be seen, reference 14 is right. It can be clearly seen that there is less minimum heating and cooling requirement is needed with the conventional furnace compared with the SWR. There is also more ethylene produced with the conventional furnace. The energy consumption determination is done by dividing the sum of the duty of the whole plant with the ethylene yield in kg/s.

Energy conumption SWR vs furnace with pinch

0

200

400

600

800

1000

1200

6 6.5 7 7.5 8 8.5 9

Ethylene yield (kg/s)

Ene

rgy

cons

umpt

ion

(MJ)

T steam in SWR (K)

Residence time in SWR (s)

Pressure before shock in SWR(bar)

Mach speed in SWR (-)

T conventional furnace (K)

SDF in SWR

Figure 5-21 Energy consumption SWR vs conventional furnace with pinch

48

Energy conumption SWR vs furnace without pinch

0500

10001500200025003000350040004500

6 7 8 9

Ethylene yield (kg/s)

Ene

rgy

cons

umpt

ion

(MJ)

T steam in SWR (K)

Residence time inSWR (s)

Pressure before shockin SWR (bar)

Mach speed in SWR (-)

T conventional furnace(K)

SDF in SWR

Figure 5-22 Energy consumption SWR vs conventional furnace without pinch

So, why is the energy consumption of the SWR so high? The biggest difference lay down in the steam production in the SWR. There is a tremendous energy needed to heat up the steam at given SDF. This SDF increase the flow of the steam. If the hydrocarbon flow that enters the SWR increases, the flow of the steam also increases. To obtain the given temperature, more energy must be pumped into the heat exchanger, which brings the steam at desired temperature. On the other hand the conventional furnace has a fixed steam flow. This is lower compared with which the SWR needs (approximately 0.3 kg steam/kg hydrocarbon flow). The energy consumption for the conventional furnace stabilizes at higher furnace temperatures. This can be seen in figure 5-23. At higher furnace temperature the energy consumption is approximately 20 MJ/kg ethylene. This value corresponds with reference 23. This reference claims for a typical steam cracking, the energy consumption is approximately 18.8-20 (according to Technip licensor).

Figure 5-23 energy consumption vs furnace temperature

Energy consumption (MJ/kg ethylene)

01020304050607080

1043

1063

1083

1103

1123

1143

Temperature furnace (K)

Ene

rgy

cons

umpt

ion

(MJ/

kg

Eth

ylen

e)

Energy consumption

49

According to the SWR experiment, the experiment with the variation of the SWR pressure before shock gives the lowest energy consumption. This experiment is given in figure 5-24. Here the energy consumption is without pinch.

Figure 5-24 Energy consumption without pinch for variation of the pressure before shock

As seen in figure 5-24, one of the best scenarios has an energy consumption of approximately 154.2 MJ/kg ethylene. This is the lowest energy consumption of al the experiment with the SWR. Lower than this consumption is not achieved. But compared with the conventional furnace, the energy consumption of the SWR is much more than the conventional furnace (factor of approximately 7.5). And another observation is that at the lowest energy consumption, the ethylene yield is 7.71 kg/s. For the conventional furnace the yield is for al experiment above 8.5 kg/s.

Energy consumption (MJ per kg ethylene) with variation of the pressure before shock

152,00

154,00

156,00

158,00

160,00

162,00

164,00

7,60 7,80 8,00 8,20

Ethylene Yield (kg/s)

Ene

rgy

cons

umpt

ion

(MJ/

kg e

thyl

ene)

Energyconsumptionwithout pinch

50

6 Environmental impact Minor important of this study is the environmental damage that can occur by using the SWR. What kind of impact has the SWR on the environment? Deceleration of the components and the shock could produce a large amount of sound. Because the SWR works at high velocities, it is important that during the shock, the noise production must be isolated if sound exceed the hazard and risk limit. Some references and books are found according to noise control with high velocity shocks. The calculation of noise which is given in chapter 6.1, is an indication, because the complexity of this research. In chapter 6.2, the investigation to enclose the SWR has been done. This is done with a silencer-muffler. Reference [24] is used to work with an absorptive silencer. Another environmental problem that can be pointed as risk is the vibration of the SWR. As the stream enters the shock part, the vibration can be significant high. This can be a risk, for example the sealing ring used in the SWR and the pipelines. The worse case scenario that can happen is an explosion due to leakages. An option for this problem is given in chapter 6.3.

6.1 Sound power calculation Gas jet generates noise through fluctuating pressures from the turbulence and shearing stresses, as the high-velocity gas impacts with the ambient gas. The nature of the noise from jets cannot be accurately predicted, because of the complex nature of the jet itself and the uncertainties associated with turbulence, nozzle configuration, temperature. However, first-order estimates can be derived from empirical data obtained for the most part from experimentation in the aviation industry. The earliest measurements of jet noise demonstrated that intensity and noise power varied very closely with the eighth power of the jet exit velocity (Lighthill’s eighth power law), and it is now generally agreed that the overall sound power P(W) can be expressed as

8 20

50

K U DP

c

ρ= i i i

(6.1)

where K is a constant, with a value 3–4; D is the jet diameter (in meters); U is the jet flow velocity (m/s); ρ0 is the density of ambient air (kg/m3); and c0 is the ambient speed of sound (m/s). With the overall sound power P, it is possible to calculate the overall source power as

0

( ) 10 logW

PL dB

P= = ⋅ (6.2)

51

Where P is the overall sound power and P0 has a value of 10-12. With the overall sound power equation, it is also possible to calculate the theoretical maximum sound intensity. This theory claims, al the kinetic energy is 100% converted into sound (so no temperature increases). This means that the kinetic energy has a maximum. The

theoretical sound power is been determined with the kinetic equation 21

2m v⋅ ⋅ .

The experiment setup up is done by varying the mach speed in the Matlab SWR model. The starting parameters are used, which were investigated early. In table 6-1 the parameters that are used are given.

Mach speed (-) Ethane feed SWR (mol/s)

Steam temperature

(K)


1.6 579,2 1400 1.4 1.7 578,9 1400 1.4 1.8 578,5 1400 1.4 1.9 577,9 1400 1.4 2.0 576,9 1400 1.4 2.1 577,6 1400 1.4 2.2 577,2 1400 1.4

Table 6-1 Input values in Matlab to determine sound power

The SDF is again 11.1. With these inputs, the SWR model in Matlab, calculated some parameters. These parameters are needed to calculate the sound power. The calculated parameters, which are calculated, are given in table 6-2.

Mach speed (-)

Kinetic energy (kW)

Diameter SWR tube

before shock (m)

Area SWR tube

before shock (m2)

Density composition before shock

(Kg/m3)

Velocity of the fluid (m/s)

Maximum attainable velocity (m/s)

1.6 16223 0,656 0,3379 0,8036 1100 756,0 1.7 14715 0,6305 0,3122 0,9088 1160 757,4 1.8 13502 0,6079 0,2902 1,0207 1210 758,5 1.9 12479 0,5868 0,2704 1,1394 1260 759,5 2.0 11610 0,5671 0,2525 1,2649 1310 760,3 2.1 10864 0,5486 0,2363 1,3973 1350 760,9 2.2 10221 0,5311 0,2215 1,5367 1390 761,5

Table 6-2 Output parameters which are generated with SWR Matlab model.

It is possible to determine the maximum theoretical sound power with the overall sound power formula. And it is possible to determine the sound power according to the Lighthill’s eighth power law. These outputs are given in table 6-3.

52

Mach speed (-) Maximum theoretical

sound intensity (dB)

Overall sound power

according to Lighthill’s

eighth power law (W)

Sound intensity

according to Lighthill’s

eighth power law (dB)

1.6 192,10 72983 168,63 1.7 191,68 110408 170,43 1.8 191,30 161955 172,09 1.9 190,96 230171 173,62 2.0 190,65 318128 175,03 2.1 190,36 428341 176,32 2.2 190,09 563555 177,51

Table 6-3 Sound intensities at different mach speed

As seen in table 6-3, the theoretical maximum sound intensity is approximately 192 dB. With the correlation of Lighthill’s eighth power law, the sound intensity varies between approximately 168-177 dB. This is still to high. At 166 dB according to reference 25, the buildings and houses have approximately a 50 % chance of survival at short distance. At 177 dB these survivals decrease to 30 %. But, the SWR will produce fewer decibels because this sound intensity determination is based on an open-end expansion. The SWR has a closed end. This will reduce some sound intensity. But still, on intuition, the sound intensity will be still high. It will be at least 120 dB. This because, if the kinetic energy in an open-end system is 1 W, the sound intensity is 120 dB according to the source power equation. So the SWR needs to be enclosed. One of the options is to use a muffler/silencer. After some investigation, a muffler/silencer cannot decrease the power intensity of the sound to acceptable levels. So another option is to use a bunker under the ground level.

6.2 Enclosure of the SWR with a bunker At chapter 6.1, it is seen that the SWR really needs a silencer. Due to high environmental impact and also for the human health. The best option is to use a bunker which a material that adsorb the sound. The sound must be adsorpted, that outside the bunker, the sound intensity must be below approximately 85 dB. Because at 85 dB the hearing damage starts. Widely used configuration is a concrete bunker below the ground level. Concrete adsorb sound and has a Noise Reduction Coefficient vary from 0.05-0.35 [26]. The Noise Reduction Coefficient (NRC) is a scalar representation of the amount of sound energy absorbed upon striking a particular surface. An NRC of 0 indicates perfect reflection; an NRC of 1 indicates perfect absorption. To increase the NRC, a material can be put on the concrete wall of the bunker. This material can be fiberglass. Fiberglass has a high NRC (0.90-0.95). So it is possible to reduce sound outside the bunker. But inside the bunker, the sound is still at high levels. Normally this has no or less influence on the environmental. But environmental safety is also safety of the employees. If some equipment has to be changed, the employee has to work in the SWR. The best scenario is to shut down the SWR, but this will not done at every repair. It would have a negative impact on the production of ethylene. Using earplugs is a good option, but is the sound power is approximately 150 dB, so this will not help the body. At say 148 dB, human vibration

53

is very uncomfortable and slightly painful. At 149 dB human lungs and breathing starts to vibrate to the sound. So the choice will be a big problem. If the sound power is high, 2 options can be used. To shut down the SWR, or use clothes and earplugs that protects all of the body. This topic is new and an important topic.

6.3 Vibration control SWR As said, there is a risk when the SWR is used. Due to the shock, vibration will occur. To absorb this vibration, spring mounts can be used. Spring mounts are the widest use of al vibration isolation. They are particularly applicable where large heavy equipment as a SWR is to be isolated. The metal springs allow for large deflections and as such are especially where large loads and very low forcing frequencies are present. Without isolation, the SWR will produce an amount of vibration, which can result in leakage and in a wore case, explosion could occur. So the SWR in the bunker needs these spring’s mounts at every corner, perhaps more. Table 6-4 shows, which spring mounts, can be used (type ‘SLF’ mount) [24]. Because the weight and vibration frequency of the SWR is unknown, different types of mounts are given.

Mount no. Mount constant (kg/m)

Capacity (kg)

SLF-409 8928 454 SLF-410 11607 590 SLF-411 16786 853 SLF-412 20536 1043 SLF-413 3571 1361 SLF-414 47859 1814 SLF-415 62502 2431 SLF-416 84825 3175 SLF-417 111612 43091 SLF-418 111612 5670 SLF-419 146435 7439 SLF-420 200902 10206 SLF-421 267869 13608 SLF-422 357159 18144

Table 6-4 Mount type and properties [24]

54

7 Conclusion and recommendations

7.1 Embedding of the SWR The main goal is embedding of the SWR in an ethylene plant and this is successfully simulated in AspenTech. With the user-model of the SWR and the user model for the SDF correction, the SWR can simulate its behavior. The mixing section is based on references and the configuration of distillation columns were such that, minimum energy requirement were necessary. The columns are working below 30 bars.

7.2 Energy consumption Based on the experimental results, the overall conclusion is that the SWR is an energy slurping process compared with the conventional furnace for the production and separation of ethylene. Chapter 5.2.5, confirm this conclusion. In this chapter figure 5-18 and 5-19 gives the energy consumption of the 2 processes. As it can be seen in these figures, the conventional furnace needs less minimum heating and cooling energy to produce ethylene. The ethylene yield is also higher at all conventional furnace experiments. In all the experiments, the conventional furnace wins. The major reason why the SWR needs more energy is due to heating up the steam. This steam is controlled by a SDF. So if the conversion of ethane is low, the recycle of ethane is higher. A higher ethane feed heading to the SWR results in higher steam flow. If the recycle of ethane is high, de-ethanizer distillation column also need more energy to achieve the given conditions. At higher furnace temperature, normally, the needed duty would increase. But in this case, this is not true. As it can be seen in figure 5-5, chapter 5.1.1, the duty needed, stabilizes. The reason of this behavior is that at higher furnace temperatures, the conversion of ethane is high, so the overall flow of the hydrocarbon heading to the furnace decreases. This is also valid for the SWR, but the SWR needs more energy due to increase of the steam temperature.

7.3 Ethylene yield The SWR has also an ethylene production limit. In al the SWR experiment, the highest ethylene yielding that was achieved, was approximately 8.44 kg/s. Higher ethylene yield is not achieved. At this yield the residence time was 0.005 seconds. Higher residence time gives a decrease in ethylene yield (7.70 kg/s). For the conventional furnace the maximum yield, which is achieved, was 8.63 kg/s. This means more ethylene can be produced with a conventional furnace. The reason of this difference is in the configuration. The maximum yield in the conventional furnace was done at a furnace temperature of 1113 K. Here the ethane recycle is 0.35 kg/s. This means the ethane conversion is very high. A strange behavior of the conventional furnace is that there is no 1,3-Butadiene produced. In the SWR, 1,3-butadiene is produced. The reason of this behavior could be that the SWR reactor is over cracking. Over cracking leads to increase in secondary reactions.

55

7.4 Sound and vibration control According to chapter 6, the SWR can produce a lot of sound. Fortunately, this can be reduces with respect to the environment. Without enclosure and according to the Ligthill’s eight-power law, the sound power is approximately 170 dB. This sound power is based on open end after the shock. The SWR is a closed end, so this sound power is lower. But how lower, is unknown. More research must be done to determine this sound power. On the other hand, for example, if the sound is so high, it can be reduced to acceptable sound. Using a bunker and fiberglass, this can be achieved. But this solution does not work for inside the bunker. For fixing some utility in the bunker will radiate the employee by this sound power. And earplugs are not enough to protect the employee. Whole the human body must be protected. The SWR also produce vibration. Without vibration adsorption, in a manner of time there will be leakages and in a worse case scenario an explosion. On the hand of the weight of the SWR, mount springer can be used. These mounts will absorb the most energy. To have proper result of the sound and vibration, a pilot model has to be made. On the hand of this model, the sound power and vibration can be better determined.

7.5 Recommendations Based on the experiments, the SWR is an energy slurping process. The conventional furnace needs less energy and with a conventional furnace ethylene yield is higher. The SWR simply needs tremendous of energy to heat up the steam. If this energy, to heat up the steam, can be generated in a cheaper way, maybe the SWR make a chance to competitive with the conventional furnace. This recommendation is based on a high SDF. But if the SDF is lower, the separation section uses large amount of energy. If this energy in the separation section can be decreased, lower SDF is favorable. The integrator, which is used in the SWR, must be configured properly. The maximum step size must be at least 0.01. A higher maximum step size gives unreliable results. Lower maximum step size is better but Aspen needs a lot of iteration. At a maximum step size the average step size of the residence time variation was 750 iterations. Sometimes the iteration was more than 5000. Because of the minor importance of the environmental impact of the SWR, few researches have been done. This means that this in not a research topic for the future or maybe a thesis subject. Stability and reliability SWR Aspen model After some validation, the matlab model and the aspen model gave almost identical outputs. For the components methane and 1,3-butadiene was a little deviation. The reason of this difference is that the integrators are different. Matlab and Aspen uses

56

different integrators. In matlab a general integrator is used, named ode15s. This integrator solves stiff differential equations. Aspen use also a differential solver but unfortunately it is unknown which solver Aspen uses. After some tests and validation, all the output parameters have a deviation less than 1%. And below this percentage, these outputs are acceptable. Another reason why deviation occurs can is the rounding off of values. Matlab uses 15 digits after a dot. Aspen uses 8 digits. I can be said that the reliability of the SWR made in Aspen by a Fortran user model is reliable due to the minimum deviation between the 2 applications. The stability of the SWR is another story. The SWR Aspen model needs a lot of iterations. The reason of this behavior is that in the loop, there are fluctuations. The cause of these fluctuations is in the ethane recycle stream. At every iteration, the ethane recycle changes. So the overall hydrocarbon flow also changes. Due to this change, the steam flow changes. So at every iteration, the SWR gets changed hydrocarbon and steam flow. When Aspen find a point below the error tolerance, it immediately stops and gives the results. The tolerance, which is used in the experiment, is 10-3. Higher tolerance will iterate sooner and lower tolerance will need more iterations. For some experiments, sometimes the SWR model needs more than 500 iterations due to the fluctuations. So it can be said that the SWR is reliable but for the stability it must be looked with a critical eye. To reflect accurate the user model in ApsenTech, the model must be tuned up in order to increase the stability and decrease the fluctuation at every iteration.

57

Literature [1] Oil Gas J. 94 (1696) May 13th, special report. [2] Hydrocarbon process. 74 (1995) 29. [3] W. Weirauch, hydrocarbon Process. 75 (1996) May, 21. [4] Asian Chemical News 1 (1995) 8. [5] K. Weissermel, H.-J. Arpe: Indusstrielle Organische Chemie, 4th ed., VCH Verlagsgesellschaft, Weinheim 1994. [6] D.Lambart et al., Analysis Magazine 23 (1995) no. 4, M9-M14. [7] K.M.Watson, E.F. Nelson, Ind. Eng. Chem. 25 (1933) 880-887. [8] H.M. Smith: “Correlation Index to Aid in Interpreting Crude-Oil Analyses,” U.S. Bureau of Mines Technical Paper no. 610, 1940. [9] S. B. Zdonik, E. J. Green, L. F. Hallee, Manufacturing Ethylene 3-17 (1968) [10] A Review of Short Residence Time Cracking Processes. 36 (1995) Vol 3. [11] Ethylene. Heinz Zimmermann, Roland Walzl, Federal Republic of Germany [12] Modeling of thermal cracking kinetics. Sundaram, Chemical Engineering Science (1977), Vol 32 pp 601-608 [13] Petrochemical pyrolysis with shock waves, Knowlen, Mattick, Department of Aeronautics and Astronautics, University of Washington Seattle, WA 98195 [14] Shock controlled reactors, Mattick, Hertzberg, Russell, Department of Aeronautics and Astronautics, University of Washington Seattle [15] Ethane cracking by means of a shock wave reactor, R.Bosma, December 2005, Faculty of chemical engineering, TUDelft. [16] Introductory Gas Dynamics, Alan Chapman, HRW Series in Mechanical Engineering, 1971, Rinehart and Winston [17] www.cmaiglobal.com/presentations/meramo.pdf [18]nr.louisiana.gov/sec/execdiv/techasmt/presentations/IETC_Chemical_Marketing_Assoc_Inc_20040501.pdf [19] Dente, M.; Ranzi, E.; Goossens, A. G. Detailed Prediction of Olefin Yields from Hydrocarbon Pyrolysis through a fundamental Simulation Model (SPYRO). Comput. Chem. Eng. 1979, 3, 61-75. [20] Froment, G. F. Kinetics and reactor design in the thermal cracking for olefins production. Chem. Eng. Sci. 1992, 49 (9-11), 2163-2177. [21] Ethane cracking by means of a Shock Wave Reactor, Bosma R, December 2005, TUDelft, Faculty of chemical engineering, the Netherlands. [22] Grantom RL and Royer DJ (1987) ‘Ethylene’ in: Gerhatz W, et al. (eds) Ullmann’s Encyclopedia of Industrial Chemistry A10, 5th ed., VCH, Weinheim, pp.45-93 [23]Olefins from conventional and heavy feedstocks: Energy use in steam cracking and alternative processes Tao Ren, Martin Patel, Kornelis Blok, Department of Science, Faculty of chemistry, Utrecht, Netherlands [24] Industrial noise control, Fundamentals and applications, Lewis H.Bell, Douglas H.Bell, second edition, Marcel Dekker INC. ISBN: 0-8247-9028-6, page 277 [25] http://www.makeitlouder.com/Decibel%20Level%20Chart.txt [26] http://www.nrcratings.com/nrc.html [27] W. C. Petterson, T. A. Wells, Chem. Eng. 84 (1977) Sept. 26, 76 – 86. [28] A. J. Weisenfelder, C.N. Eng., Personal Communication, C. F. Braun&Co., Alhambra, Calif., Aug. 1985 [29] J.A.Moulijn, Chemical Process Technology, Johm Wiley & Sons, ISBN: 0417630098

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Appendix

59

Appendix A Determination Nozzle and mixing configuration

The nozzle geometry to accelerate, adiabatically and frictionless, is calculated with the equation of Venant and Wantzel. This equation is given in 9.

*( 1) / 2( 1)0

0

2( )

1k k

e

pm k A

A R k AT+ −= ⋅ ⋅ ⋅

+ (A-1)

m is here the mass flow rate, p0 the stagnation pressure (pressure without any energy exchange and without losses), T0 the stagnation temperature. The ratio Ae/A

* is the surface ratio of the surface after the expansion divided by the surface of the throat for a fixed kappa. This ratio is isentropic and for this, there is an isentropic table to design the throat for a particular velocity after the expansion. Because it’s isentropic, the temperature ratio, pressure ratio is also fixed. In Appendix A the determination of the throat surface calculation is given. To determine the mixing distance, the plenum pressure ratio must be known. Figure 2-5 shows the mixing distance as function of plenum pressure ratio for Ethane-Steam flow expanded through same nozzle array.

Figure A-7-1 Mixing distance as function of plenum pressure ratio [13]

For determining the nozzle throat, the kappa has taken into consideration. Because the kappa is variable, the first step is to approach average kappa. The used methods are iterative, but are considerably easy and fast. Determining the nozzle throat, the next equations are used:

*

1p

Rc

κκ

=−

(A-2)

60

0

**

1

T

p p

Rh c dT c T T

κκ

= ≈ = − ∫ (A-3)

211 *

2tT T Mκ − = +

(A-4)

/( 1)21

1 *2tp p M

κ κκ −− = +

(A-5)

Here is Tt and pt the stagnation temperature and pressure. This stagnation state means that

1. without any energy exchange (Q=W=0) and 2. without losses

This also means that this is isentropic. To find the throat area, first the properties of perfect solution must be determined. The solution for this, it is given below in steps and figure A-2 defined this.

T1=Tt1

p1=pt1

V1=0

1 2 3

M3

p3

T3

Figure A-7-2 Throat nozzle determination

1. Assume T3 from the perfect gas, constant kappa solution. (This is done with the isentropic table)

2. Find kappa3 (for higher temperature kappa=1.3 3. Compute an average kappa at station 3 from

3 13

2

κ κκ− += (A-6)

4. Now sine 3 1t th h= from the energy equation,

61

3 3 ~1 1

3

3 1

1

( 1)

( 1)

p t p t

t t

c T c T

T Tκ κ

κ κ

− −

−

−

≈

− ≈ −

(A-7)

5. Now still using the average kappa for properties at station 3 as long as it are not locally based. The next equation is used to get an estimate for M3 ( The stagnation pressure remains constant because the expansion is isotropic).

3 3( 1) /( )

13

23

2* 1

1

t

t

pM

p

κ κ

κ

− −−

−

≈ − −

~ (A-8)

6. Knowing M3 and Tt3, it is possible to compute T3 with the

equation 211 *

2tT T Mκ − = +

(A-9)

7. Now the value of T3 can be compared with the assumed T3 in step 1. 8. Now kappa3 can be reevaluated at the new T3 value and see if it differs

appreciably from the value assumed originally. This value can be iteratively determined.

9. The last step is to determine the throat area with the next equation

3 3 1 31*

2 3 3 3 3 1

0.579A A Tp

A A M p T

κκ

= ≈

(A-10)

A3/A2 is the nozzle area ratio. With this equation it is now possible to calculate the A2 throat area.

62

Appendix B Shock property calculation The shock property calculation is done with the next conservation laws: Continuity 1 1 1 2 2 2A Aρ υ ρ υ= (B-1)

Momentum 2 2

1 1 1 2 2 2p pρ υ ρ υ+ = + (B-2)

Energy 2 21 2

1 22 2h h

υ υ+ = + (B-3)

As at the continuity law can be seen is that the area is constant during the shock is constant. This is an assumption, which is taken from reference [16]. The above equations can be considered in which gas is an ideal gas. For this case now the next relations can be used: p RTρ= (B-4)

2c RTκ= (B-5)

1h RT

κκ

=−

(B-6)

Mc

υ= (B-7)

When these relations are substituted in continuity, momentum and energy equation, next is obtained:

Continuity 1 1 2 2

1 2

p M p M

T T= (B-8)

Momentum 2 21 1 1 2 2 2(1 ) (1 )p M p Mκ κ+ = + (B-9)

Energy 2 21 21 1 2 2

1 11 1

2 2T M T M

κ κ− − + = +

(B-10)

63

Appendix C Determination pyrolysis section SWR This configuration is taken out of the report of R.Bosma. After validation, my opinion was slightly different compared with his opinion. Most of the corresponding equations are taken out his report. Some equations are corrected and put in the matlab script, which he made. There are 7 reactions and 9 components involved in this kinetic model. The reactions are given above with the components. So this kinetic model can converted into a stoechiometric matrix as given in table A-1.

Table A-1 Stoechiometric model

In the pyrolysis step, the cross-sectional area is not constant. It is a function of the angle α, the length of the reactor z and inlet pyrolysis diameter. So to determine the cross-sectional area, first the diameter must be determined,

0 2 tanD D z α= + (C-1)

The cross-sectional area is determined by,

21

4A Dπ= (C-2)

The total molar flow is given by,

iF F=∑ (C-4)

The molar concentration is given by,

ii

F Pc

F RT= (C-5)

For modeling this into Matlab, the rate of reaction is important. This rate of reaction matrix is made when the stoechiometric matrix is multiplied by –1 and al the negative

64

values are set to zero. The second order reaction are set o 1 according to Sundaram 1977. Now the rate of reaction mate becomes,

Table A-2 Rate of reaction matrix

The i-th column is the components i and the j-th row is the reaction j. The corresponding rate rj of reaction j is defined as,

, ,

8/

0,1

a j react jiE RT M

j j ii

r k e c−

=

= ∏ (C-6)

where k0,j and Ea,j are the kinetic constants for reaction j and Mreact,ji is the corresponding element in column i, row of Mreact. The change in component i mole flow is now found by,

,i

stoech i

dFrM

dV= with dV A dz≈ i (C-7)

where r is the vector that contains j reaction rates and Mstoech,i is column i of Mstoech. The steam flow rate is given by the steam diluents factor (SDF) and this is coupled by the ethane feed and not the complete feed entrance. The equation becomes,

*steam ethaneF SDF F= (C-8)

The velocity u is given by,

F RTu

A P= (C-9)

The residence time is given. With this residence time, the reactor length can be determined by,

z

uτ = (C-10)

The molar heat of reaction is the sum of the molar heats of formation of the reactants and products,

65

,f j stoech ji f iH M H∆ = ∆∑ (C-11)

The actual molar heat of formation at a temperature T can be found by,

0(298 ) ,

298

T

f j f i K p iH H C dT∆ = ∆ + ∫ (C-12)

The specific heat of the components is given by,

2 3,p i i i i ic A BT C T DT= + + + (C-13)

According to first law of thermodynamics, the energy balance is,

in in out out

dEF E F E P V T V

dt= ⋅ − ⋅ + ∆ + ∆i i (C-14)

Because it’s steady state,

0dE

dt= (C-15)

A different approach is the momentum balance. Reference 21 claims that the momentum balance is,

2

(2 4 tan )xdP uf

dz D

ρα= − + (C-16)

In this equation, a assumption error has been make. This equation claims that the surface area is not changing, but is does. The surface area is a function of the diameter so the momentum balance becomes,

( ) ( )( ) ( ) wzz dz z z dz z

DdzPA PA uA u uA u F

A

τ πρ ρ+ +

− + − + + (C-17)

in which,

21

2w f uτ ρ= ⋅ (C-18)

66

Rewriting the momentum balance gives,

2( ) (( ) ) 1

2

d PA d uA u Df u

dz dz A

ρ πρ+ = − ⋅ ⋅ (C-19)

Knowing that,

z

uτ = (C-20)

where τ is in sec, the mechanic energy balance becomes,

2

2xdP uf u

dt D

ρ = − ⋅ ⋅ ⋅

(C-21)

where xP is a new variable given by,

2

xP P uρ= + (C-22)

Mass density ρ is given by,

w

PM

RTρ = ⋅ (C-23)

wM is the mean molecular weight and this is given by,

,i w iw

F MM

F= ∑ (C-24)

The friction factor can be found by,

0.20.046Ref −= (C-25) for 5Re 10⟩ . The Reynolds number is given by,

ReuDρη

= (C-26)

The dynamic viscosity η is given by the next equation,

i iF

F

ηη = ∑ (C-27)

The dynamic viscosity iη of component i, the correlation of Froment 1979 is used

after some checking if the correlation is applicable for this system. The correlation is given by,

67

2/31/ 2

, , 71/6, , ,

1.9 0.29 101.0134

w i c ii

c i c i c i

M P T

T Z Tη −

= ⋅ ⋅ − ⋅

(C-28)

,c iT , ,c iP and ,c iZ are the critical temperature, pressure and compressibility factor of

component i.

68

Appendix D Input values used to determine accuracy of the Aspen SWR model Input values for the parameters are given below in table. For every experiment a number is given Experiment No Hydrocarbon feed Steam SWR

Flow (mol/s)

T (K)

P (bar)

Flow (mol/s)

T (K)

P (bar)

P before shock (bar)

Mach speed Residence time (s)

1 C2H6: 310 C2H4: 3.1 C3H6:2.48

350 3 3441 1500 5 1.4 2.4 0.1

2 C2H6: 310 C2H4: 3.1 C3H6:2.48

350 3 3441 1400 5 1.4 2.4 0.1

3 C2H6: 310 C2H4: 3.1 C3H6:2.48

350 3 3441 1300 5 1.4 2.4 0.1

4 C2H6: 310 C2H4: 3.1 C3H6:2.48

350 3 3441 1200 5 1.4 2.4 0.1

5 C2H6: 310 C2H4: 3.1 C3H6:2.48

350 3 3441 1100 5 1.4 2.4 0.1

6 C2H6: 310 C2H4: 3.1 C3H6:2.48

350 3 3441 1000 5 1.4 2.4 0.1

7 C2H6: 310 C2H4: 3.1 C3H6:2.48

450 3 3441 1500 5 1.4 2.4 0.1

8 C2H6: 310 C2H4: 3.1 C3H6:2.48

400 3 3441 1500 5 1.4 2.4 0.1

9 C2H6: 310 C2H4: 3.1 C3H6:2.48

350 3 3441 1500 5 1.4 2.4 0.1

10 C2H6: 310 C2H4: 3.1 C3H6:2.48

300 3 3441 1500 5 1.4 2.4 0.1

11 C2H6: 310 C2H4: 3.1

350 2.5 3441 1500 5 1.4 2.4 0.1

69

C3H6:2.48

12 C2H6: 310 C2H4: 3.1 C3H6:2.48

400 2.0 3441 1500 5 1.4 2.4 0.1

13 C2H6: 310 C2H4: 3.1 C3H6:2.48

350 1.5 3441 1500 5 1.4 2.4 0.1

14 C2H6: 310 C2H4: 3.1 C3H6:2.48

400 1.0 3441 1500 5 1.4 2.4 0.1

15 C2H6: 310 C2H4: 3.1 C3H6:2.48

350 3.0 3441 1500 10 1.4 2.4 0.1

16 C2H6: 310 C2H4: 3.1 C3H6:2.48

400 3.0 3441 1500 8 1.4 2.4 0.1

17 C2H6: 310 C2H4: 3.1 C3H6:2.48

350 3.0 3441 1500 3 1.4 2.4 0.1

18 C2H6: 310 C2H4: 3.1 C3H6:2.48

400 3.0 3441 1500 1 1.4 2.4 0.1

19 C2H6: 250 C2H4: 2.5 C3H6:2.0

350 3 2775 1500 5 1.4 2.4 0.1

20 C2H6: 200 C2H4: 2.0 C3H6:1.6

350 3 2220 1500 5 1.4 2.4 0.1

21 C2H6: 350 C2H4: 3.5 C3H6:2.8

350 3 3885 1500 5 1.4 2.4 0.1

22 C2H6: 400 C2H4: 4.0 C3H6:3.2

350 3 4440 1500 5 1.4 2.4 0.1

70

Appendix E Output values used to determine accuracy of the Aspen SWR model

Research No Aspen 1 2 3 4 5 6 7 8 9 10 11

Methane (mol/s) 29.49 16.24 6.82 2.58 0.95 0.20 31.35 30.39 29.49 28.69 29.49 Acetylene (mol/s) 1.00 1.72 2.04 1.92 0.91 0.19 0.91 0.96 1.00 1.03 1.00 ethylene (mol/s) 206.16 158.76 91.60 29.48 5.88 3.23 209.98 208.05 206.16 204.36 206.16 ethane (mol/s) 63.34 131.65 213.79 282.51 307.15 309.87 56.61 60.03 63.34 66.38 63.34

propylene (mol/s) 0.88 1.05 0.75 0.60 1.57 2.29 0.84 0.86 0.88 0.90 0.88 propane (mol/s) 2.33 1.51 0.78 0.22 0.02 0.00 2.44 2.38 2.33 2.28 2.33

1,3-butadiene (mol/s) 13.38 6.36 1.84 0.19 0.00 0.00 14.36 13.86 13.38 12.96 13.38 hydrogen (mol/s) 229.22 168.67 92.50 26.82 2.80 0.13 234.88 232.01 229.22 226.64 229.22

water (mol/s) 3441.00 3441.00 3441.00 3441.00 3441.00 3441.00 3441.00 3441.00 3441.00 3441.00 3441.00 Temperature (K) 1129.62 1088.68 1062.38 1030.80 968.72 889.70 1136.68 1132.92 1129.62 1126.75 1129.62 Pressure (bar) 11.28 11.34 11.40 11.46 11.53 11.60 11.27 11.28 11.28 11.28 11.28

Research No Matlab 1 2 3 4 5 6 7 8 9 10 11

Methane (mol/s) 29.36 16.21 6.80 2.57 0.95 0.20 31.20 30.24 29.36 28.59 29.36

Acetylene (mol/s) 1.00 1.72 2.04 1.92 0.91 0.19 0.91 0.96 1.00 1.03 1.00

ethylene (mol/s) 206.30 158.82 91.56 29.47 5.88 3.23 210.15 208.21 206.30 204.48 206.30

ethane (mol/s) 63.38 131.64 213.85 282.53 307.15 309.87 56.66 60.11 63.38 66.43 63.38

propylene (mol/s) 0.89 1.05 0.75 0.60 1.57 2.29 0.84 0.87 0.89 0.90 0.89

propane (mol/s) 2.33 1.51 0.78 0.22 0.02 0.00 2.44 2.38 2.33 2.28 2.33

1,3-butadiene (mol/s) 13.32 6.34 1.84 0.19 0.00 0.00 14.28 13.78 13.32 12.91 13.32

hydrogen (mol/s) 229.24 168.70 92.45 26.80 2.79 0.13 234.90 232.01 229.24 226.65 229.24

water (mol/s) 3441.00 3441.00 3441.00 3441.00 3441.00 3441.00 3441.00 3441.00 3441.00 3441.00 3441.00

Temperature (K) 1129.59 1088.66 1062.42 1030.82 968.72 889.70 1136.64 1132.89 1129.59 1126.72 1129.59

Pressure (bar) 11.29 11.35 11.41 11.47 11.54 11.61 11.29 11.29 11.29 11.30 11.29

Research No Deviation between Aspen and Matlab (%) 1 2 3 4 5 6 7 8 9 10 11

Methane (mol/s) 0.42 0.19 0.18 0.04 0.05 0.23 0.46 0.52 0.42 0.38 0.42 Acetylene (mol/s) 0.02 0.06 -0.01 0.00 0.05 0.23 0.00 -0.11 0.02 -0.03 0.02 ethylene (mol/s) -0.07 -0.03 0.05 0.06 0.04 0.01 -0.08 -0.08 -0.07 -0.06 -0.07 ethane (mol/s) -0.06 0.01 -0.03 -0.01 0.00 0.00 -0.08 -0.13 -0.06 -0.07 -0.06

propylene (mol/s) -0.06 0.02 0.02 0.01 -0.03 -0.02 -0.09 -0.16 -0.06 -0.08 -0.06 propane (mol/s) 0.00 -0.01 0.07 0.07 0.09 0.25 -0.01 0.05 0.00 0.02 0.00

1,3-butadiene (mol/s) 0.46 0.23 0.31 0.27 0.28 0.61 0.51 0.58 0.46 0.43 0.46 hydrogen (mol/s) -0.01 -0.01 0.06 0.07 0.09 0.25 -0.01 0.00 -0.01 0.00 -0.01

water (mol/s) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Temperature (K) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Pressure (bar) -0.11 -0.11 -0.11 -0.11 -0.12 -0.12 -0.11 -0.11 -0.11 -0.11 -0.11

71

Research No

Aspen 12 13 14 15 16 17 18 19 20 21 22 Methane (mol/s) 29.49 29.49 29.49 29.49 29.49 29.49 29.49 23.81 19.09 33.30 37.98

Acetylene (mol/s) 1.00 1.00 1.00 1.00 1.00 1.00 1.00 0.80 0.64 1.13 1.29 ethylene (mol/s) 206.16 206.16 206.16 206.16 206.16 206.16 206.16 166.25 132.98 232.75 266.04 ethane (mol/s) 63.34 63.34 63.34 63.34 63.34 63.34 63.34 51.04 40.79 71.51 81.80

propylene (mol/s) 0.88 0.88 0.88 0.88 0.88 0.88 0.88 0.71 0.57 1.00 1.14 propane (mol/s) 2.33 2.33 2.33 2.33 2.33 2.33 2.33 1.88 1.50 2.63 3.00

1,3-butadiene (mol/s) 13.38 13.38 13.38 13.38 13.38 13.38 13.38 10.81 8.67 15.11 17.23 hydrogen (mol/s) 229.22 229.22 229.22 229.22 229.22 229.22 229.22 184.88 147.92 258.80 295.74

water (mol/s) 3441.00 3441.00 3441.00 3441.00 3441.00 3441.00 3441.00 2775.00 2220.00 3885.00 4440.00 Temperature (K) 1129.62 1129.62 1129.62 1129.62 1129.62 1129.62 1129.62 1129.62 1129.62 1129.62 1129.62 Pressure (bar) 11.28 11.28 11.28 11.28 11.28 11.28 11.28 11.28 11.28 11.28 11.28

Matlab 12 13 14 15 16 17 18 19 20 21 22

Methane (mol/s) 29.36 29.36 29.36 29.36 29.36 29.36 29.36 23.72 19.00 33.12 37.81

Acetylene (mol/s) 1.00 1.00 1.00 1.00 1.00 1.00 1.00 0.80 0.64 1.13 1.29

ethylene (mol/s) 206.30 206.30 206.30 206.30 206.30 206.30 206.30 166.35 133.07 232.94 266.24

ethane (mol/s) 63.38 63.38 63.38 63.38 63.38 63.38 63.38 51.08 40.83 71.59 81.86

propylene (mol/s) 0.89 0.89 0.89 0.89 0.89 0.89 0.89 0.71 0.57 1.00 1.14

propane (mol/s) 2.33 2.33 2.33 2.33 2.33 2.33 2.33 1.88 1.50 2.63 3.00

1,3-butadiene (mol/s) 13.32 13.32 13.32 13.32 13.32 13.32 13.32 10.76 8.62 15.02 17.14

hydrogen (mol/s) 229.24 229.24 229.24 229.24 229.24 229.24 229.24 184.89 147.93 258.81 295.76

water (mol/s) 3441.00 3441.00 3441.00 3441.00 3441.00 3441.00 3441.00 2775.00 2220.00 3885.00 4440.00

Temperature (K) 1129.59 1129.59 1129.59 1129.59 1129.59 1129.59 1129.59 1129.59 1129.60 1129.59 1129.58

Pressure (bar) 11.29 11.29 11.29 11.29 11.29 11.29 11.29 11.29 11.29 11.29 11.29

Deviation between Aspen and Matlab (%) 12 13 14 15 16 17 18 19 20 21 22

Methane (mol/s) 0.42 0.42 0.42 0.42 0.42 0.42 0.42 0.39 0.44 0.55 0.46 Acetylene (mol/s) 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.00 -0.08 -0.07 0.00 ethylene (mol/s) -0.07 -0.07 -0.07 -0.07 -0.07 -0.07 -0.07 -0.06 -0.06 -0.08 -0.08 ethane (mol/s) -0.06 -0.06 -0.06 -0.06 -0.06 -0.06 -0.06 -0.07 -0.10 -0.12 -0.07

propylene (mol/s) -0.06 -0.06 -0.06 -0.06 -0.06 -0.06 -0.06 -0.07 -0.13 -0.14 -0.08 propane (mol/s) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.04 0.01 0.01

1,3-butadiene (mol/s) 0.46 0.46 0.46 0.46 0.46 0.46 0.46 0.44 0.49 0.62 0.51 hydrogen (mol/s) -0.01 -0.01 -0.01 -0.01 -0.01 -0.01 -0.01 -0.01 0.00 0.00 -0.01

water (mol/s) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Temperature (K) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Pressure (bar) -0.11 -0.11 -0.11 -0.11 -0.11 -0.11 -0.11 -0.09 -0.08 -0.12 -0.13

72

Appendix F Embedded SWR in an ethylene plant

33

32 28

34

43

45 44

37

42

46

414038

39

36

35

22

2627

20

21

1918

25

24

17

231613

14

48

29

10 117

45

249

1HC-1

6

9

15

HYDROGEN

8

52

53

12

30

55

54

B42

B41

RGIBBS

B25

Q=-1692183

B21B19

Q=0

GCOOL2

Q=-17247

B15

B4GCOOL1

B13

FCOOL3

Q=-461132

FCOMP1

W=168010

PREDEM2

Q=0

B12

FCOOL2

Q=-1267202

PREDEM1FCOOL1

SEPSCRUBBER

Q=-44382

B8

Q=0

DCOOL1

Q=-60415048 DCOMP1

W=23691812

CCOOL1BHEAT1

Q=42717607

B2

ACOMP1

W=1252048

B3

B5

Q=0

B7

Q=-2827136

B10

User2

B6B11

B16

QC=18065639QR=44604312

B17

QC=2023728QR=14133585

B18

USER2

B14

Feed/Recycle section SWR

TLE and Quench System

DepropanizerScrubber

B1

ETHYLENE

Demethanizer

Deethanizer Hydrogen purification and methane burning

73

Appendix G Embedded conventional furnace in an ethylene plant

R2 R3

D3

C2H2

16

20

22

H20-6

R6 R7

34

D2

1525

43

METMIX

C2H4HC-5

35

HYDROGEN

40

38

2

H20-7

HC-1HC-2

59

9

OXYGEN

52

WATERQUENCH

SEPSCRUBBER

FCOOL1PREDEM1

PREDEM2

Q=0

FCOOL2FCOMP1

FCOOL3B3

SIEVEDCOMP1

DCOOL1

GCOOL1

B12 B13B15

B19 B21

B4

B8 B20

B22

B18

ACOMP1

B41

B42

GCOOL2

RGIBBS

B25

B2

CCOOL1

B24

BHEAT1

12

24

3

5

7

1317 18

19

21

23

28

30 31

32

Furnace TLE and Quench system Depropanizer Scrubber

Demethanizer

Deethanizer

37

39 41

Hydrogen purification and Methane burning

Feed/Recyle section

B142

B5B6

B9

75

Appendix H Experiment results This appendix contains all the experiments where the minimum heating and cooling requirements are determined. Aspen Pinch made these calculations. The table below shows how this appendix is divided.

Appendix H-1 Variation of the furnace temperature H-2 Variation of the SWR steam temperature H-3 Variation of the SWR residence time H-4 Variation of the SWR Mach speed H-5 Variation of the SWR pressure before shock H-6 Variation of the SWR SDF

The thermal data of the streams that are used to determine the material and heat balance are: • Supply temperature (ºC) • Target temperature (ºC) • Heat capacity flow rate (kW/ºC) • Enthalpy change Pinch technology presents a simple methodology for systematically analyzing chemical processes. It helps the first and the second law of thermodynamics. The first law of thermodynamics provides the energy equation for calculating the enthalpy changes in streams. The first law of thermodynamics gives the enthalpy change associated with a stream passing through a utility. The equation of the first law of thermodynamics is, H=Q±W H is the enthalpy change, Q the heat supply/demand associated with a stream and W is the mechanical work. Since there is no mechanical work: W=0 So the equation above simplifies to H=Q. The relationship becomes, Q= MCP*(Tsup-Ttar) The second law of thermodynamics determines the direction of the heat flow. The DTmin is set to 10 K. This value determines how closely the hot and cold composite curves can be pinched without violating the second law of thermodynamics.

76

Appendix H-1 Table and pinch composite of the conventional furnace with a temperature of 770 ºC

TEMPERATURE COMPOSITES (Real T, No Utils) Case: 820

HOT COLD

ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E C

0.0 100.0 200.0 300.0 400.0-200.0

0.0

200.0

400.0

600.0

800.0DTMIN =10.00 Heat Imbalance

77

Table and pinch composite of the conventional furnace with a temperature of 780ºC

COMPOSITE CURVES (Real T, No Utils)

Case: 820

ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E C

0.0 50.0 100.0 150.0 200.0-200.0

0.0

200.0

400.0

600.0


78

Table and pinch composite of the conventional furnace with a temperature of 790 ºC


Case: 820

ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E C

0.0 20.0 40.0 60.0 80.0 100.0 120.0 140.0 160.0-200.0

0.0

200.0

400.0

600.0


79



Case: 820

ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E C

0.0 20.0 40.0 60.0 80.0 100.0 120.0 140.0-200.0

0.0

200.0

400.0

600.0


80



Case: 820

ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E C

0.0 20.0 40.0 60.0 80.0 100.0 120.0 -200.0

0.0

200.0

400.0

600.0

800.0


81



Case: 820

ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E C

0.0 20.0 40.0 60.0 80.0 100.0 120.0 -200.0

0.0

200.0

400.0

600.0

800.0


82



Case: 820

ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E C

0.0 20.0 40.0 60.0 80.0 100.0 120.0 -200.0

0.0

200.0

400.0

600.0

800.0


83

Table and pinch composite of the conventional furnace with a temperature of 840ºC


Case: 820

ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E C

0.0 20.0 40.0 60.0 80.0 100.0 120.0 -200.0

0.0

200.0

400.0

600.0

800.0


84



Case: 820

ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E C

0.0 20.0 40.0 60.0 80.0 100.0 120.0 -200.0

0.0

200.0

400.0

600.0

800.0


85



Case: 820

ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E C

0.0 20.0 40.0 60.0 80.0 100.0 120.0 -200.0

0.0

200.0

400.0

600.0

800.0


86



Case: 820

ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E C

0.0 20.0 40.0 60.0 80.0 100.0 120.0 -200.0

0.0

200.0

400.0

600.0

800.0


87


COMPOSITE CURVES (Real T, No Utils) Case: 820

ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E C

0.0 20.0 40.0 60.0 80.0 100.0 120.0 -200.0

0.0

200.0

400.0

600.0

800.0


88

Appendix H-2 Table and pinch composite of the SWR with a steam temperature of 827 ºC


Case: 820

ENTHALPY X10 6 kW

TE

MP

ER

AT

UR

E C

0.0 .5 1.0 1.5 2.0 2.5 3.0 3.5 -200.0

0.0

200.0

400.0

600.0

800.0


89

Table and pinch composite of the SWR with a steam temperature of 877 ºC


ENTHALPY X10 6 kW

TE

MP

ER

AT

UR

E C

0.0 .4 .8 1.2 1.6 2.0 -200.0

0.0

200.0

400.0

600.0

800.0


90



ENTHALPY X10 6 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 .2 .4 .6 .8 1.0 1.2 -.2

0.0

.2

.4

.6

.8

1.0


91



Case: 820

ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 200.0 400.0 600.0 800.0 1000.0 -.2

0.0

.2

.4

.6

.8

1.0


92



ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 100.0 200.0 300.0 400.0 500.0 600.0 700.0 800.0 -.2

0.0

.2

.4

.6

.8

1.0


93



ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 100.0 200.0 300.0 400.0 500.0 600.0 700.0 -.2

0.0

.2

.4

.6

.8

1.0


94



ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 100.0 200.0 300.0 400.0 500.0 600.0 -.2

0.0

.2

.4

.6

.8

1.0

1.2


95



ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 100.0 200.0 300.0 400.0 500.0 600.0 -.2

0.0

.2

.4

.6

.8

1.0

1.2


96



ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 100.0 200.0 300.0 400.0 500.0 600.0 -.4

0.0

.4

.8

1.2


97



ENTHALPY X10 6 kW

TE

MP

ER

AT

UR

E C

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 -200.0

0.0

200.0

400.0

600.0

800.0


98



ENTHALPY X10 6 kW

TE

MP

ER

AT

UR

E C

0.0 5.0 10.0 15.0 20.0 25.0 -200.0

0.0

200.0

400.0

600.0

800.0


99

Appendix H-3 Table and pinch composite of the SWR with a residence time of 0.005


Case: 820

ENTHALPY X10 6 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 .5 1.0 1.5 2.0 2.5 3.0 -.2

0.0

.2

.4

.6

.8

1.0


100

Table and pinch composite of the SWR with a residence time of 0.009


Case: 820

ENTHALPY X10 6 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 .4 .8 1.2 1.6 2.0 -.2

0.0

.2

.4

.6

.8

1.0


101



Case: 820

ENTHALPY X10 6 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 .2 .4 .6 .8 1.0 1.2 1.4 -.2

0.0

.2

.4

.6

.8

1.0


102



Case: 820

ENTHALPY X10 6 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 .2 .4 .6 .8 1.0 1.2 -.2

0.0

.2

.4

.6

.8

1.0


103



Case: 820

ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 200.0 400.0 600.0 800.0 1000.0 -.2

0.0

.2

.4

.6

.8

1.0


104



Case: 820

ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 200.0 400.0 600.0 800.0 1000.0 -.2

0.0

.2

.4

.6

.8

1.0


105



Case: 820

ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 200.0 400.0 600.0 800.0 1000.0 -.2

0.0

.2

.4

.6

.8

1.0


106



Case: 820

ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 200.0 400.0 600.0 800.0 1000.0 -.2

0.0

.2

.4

.6

.8

1.0


107



Case: 820

ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 200.0 400.0 600.0 800.0 -.2

0.0

.2

.4

.6

.8

1.0


108



Case: 820

ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 100.0 200.0 300.0 400.0 500.0 600.0 700.0 800.0 -.2

0.0

.2

.4

.6

.8

1.0


109

Appendix H-4 Table and pinch composite of the SWR with Mach speed of 1.6


Case: 820

ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 200.0 400.0 600.0 800.0 1000.0 -.2

0.0

.2

.4

.6

.8

1.0


110

Table and pinch composite of the SWR with Mach speed of 1.7


Case: 820

ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 200.0 400.0 600.0 800.0 1000.0 -.2

0.0

.2

.4

.6

.8

1.0


111



Case: 820

ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 200.0 400.0 600.0 800.0 1000.0 -.2

0.0

.2

.4

.6

.8

1.0


112



Case: 820

ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 200.0 400.0 600.0 800.0 1000.0 -.2

0.0

.2

.4

.6

.8

1.0


113



ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 200.0 400.0 600.0 800.0 1000.0 -.2

0.0

.2

.4

.6

.8

1.0


114



Case: 820

ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 200.0 400.0 600.0 800.0 1000.0 -.2

0.0

.2

.4

.6

.8

1.0


115



ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 200.0 400.0 600.0 800.0 1000.0 -.2

0.0

.2

.4

.6

.8

1.0


116

Appendix H-5 Table and pinch composite of the SWR with pressure before shock of 1.1 bar


Case: 820

ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 200.0 400.0 600.0 800.0 1000.0 -.2

0.0

.2

.4

.6

.8

1.0


117

Table and pinch composite of the SWR with pressure before shock of 1.2 bar


ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 200.0 400.0 600.0 800.0 1000.0 -.2

0.0

.2

.4

.6

.8

1.0


118



ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 200.0 400.0 600.0 800.0 1000.0 -.2

0.0

.2

.4

.6

.8

1.0


119



Case: 820

ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 200.0 400.0 600.0 800.0 1000.0 -.2

0.0

.2

.4

.6

.8

1.0


120



Case: 820

ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 200.0 400.0 600.0 800.0 1000.0 -.2

0.0

.2

.4

.6

.8

1.0


121



ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 200.0 400.0 600.0 800.0 1000.0 -.2

0.0

.2

.4

.6

.8

1.0


122



ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 200.0 400.0 600.0 800.0 1000.0 -.2

0.0

.2

.4

.6

.8

1.0


123



ENTHALPY X10 3 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 200.0 400.0 600.0 800.0 1000.0 -.2

0.0

.2

.4

.6

.8

1.0


124

Appendix H-6 Table and pinch composite of the SWR with a SDF of 6.0


Case: 820

ENTHALPY X10 6 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 1.0 2.0 3.0 4.0 5.0 -.2

0.0

.2

.4

.6

.8

1.0


125

Table and pinch composite of the SWR with a SDF of 6.5


Case: 820

ENTHALPY X10 6 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 1.0 2.0 3.0 4.0 -.2

0.0

.2

.4

.6

.8

1.0


126



Case: 820

ENTHALPY X10 6 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 .5 1.0 1.5 2.0 2.5 3.0 3.5 -.2

0.0

.2

.4

.6

.8

1.0


127


COMPOSITE CURVES (Real T, With Utils)

Case: 820

ENTHALPY X10 6 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 .5 1.0 1.5 2.0 2.5 3.0 -.2

0.0

.2

.4

.6

.8

1.0


128

Table and pinch composite of the SWR with a SDF of 8


Case: 820

ENTHALPY X10 6 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 .5 1.0 1.5 2.0 2.5 3.0 -.2

0.0

.2

.4

.6

.8

1.0


129


COMPOSITE CURVES (Real T, With Utils)

Case: 820

ENTHALPY X10 6 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 .5 1.0 1.5 2.0 2.5 -.2

0.0

.2

.4

.6

.8

1.0


130



Case: 820

ENTHALPY X10 6 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 .5 1.0 1.5 2.0 2.5 -.2

0.0

.2

.4

.6

.8

1.0


131



Case: 820

ENTHALPY X10 6 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 .5 1.0 1.5 2.0 2.5 -.2

0.0

.2

.4

.6

.8

1.0


132



Case: 820

ENTHALPY X10 6 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 .4 .8 1.2 1.6 2.0 -.2

0.0

.2

.4

.6

.8

1.0


133



Case: 820

ENTHALPY X10 6 kW

TE

MP

ER

AT

UR

E X

10

3 C

0.0 .4 .8 1.2 1.6 2.0 -.2

0.0

.2

.4

.6

.8

1.0


embedding of shock wave reactor in thermal cracking

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