acme 3000 tpd methanol plant mrf-z reactor sizing

GBH Enterprises, Ltd.

ACME 3000 TPD METHANOL PLANT MRF-Z REACTOR SIZING Case Study #0618906GB/H

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Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries

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Contents

1. Background

2. Objective

MRF-Z Reactor sizing: Case study #0618906GB/H

o Lean Gas Case o Rich Gas Case

Figure 1. MRF-Z Reactor

Figure 2. Layout of MRF-Z

3 MRF-Z Reactor Design Considerations 4 MRF-Z advantages and Disadvantages

5 Sizing Results: 3000 TPD Methanol

Lean Gas Case

Rich Gas Case

APPENDIX CALCULATING THE MINIMUM TUBE PITCH OF A MRF REACTOR



1 Background Methanol is the simplest of the series of aliphatic alcohols. It is an extremely versatile chemical and is used as a raw material for a number of processes in the chemical industry. It may also be used unchanged as a solvent or cleaning fluid. Its largest single usage is oxidation to formaldehyde which is itself a raw material used in the manufacture of synthetic resins for the wood, plastics, and paint industries. Conventional Methanol processes involve the catalytic steam reforming of a hydrocarbon feedstock, typically natural gas, to give a gaseous mixture of carbon oxides and hydrogen known as synthesis gas. This mixture is then compressed and reacted over a copper catalyst bed to give methanol and some associated by-products. The pure product is obtained by fractional distillation. In other words, the process can be divided into three stages: Purification Synthesis Gas Generation Compression Methanol Synthesis Crude Methanol Purification Because of the extensive heat integration between the reforming convection section and synthesis with the radiant zone, compression, and distillation and the considerable recycle streams there is significant interaction between each of the three sections. The focus of this short case study is the examination of two feed gases, and their impact on the sizing of a proposed methanol synthesis reactor, i.e., the MRF-Z Reactor.



2 Objective: Sizing a proposed MRF-Z Reactor design for a 3000 TPD single train Methanol plant, for two feed gas cases;

o Lean Gas Case o Rich Gas Case

(See Section 3 for sizing basis)

3 MRF-Z Reactor Design Considerations The MRF-Z is a unique converter in a number of respects, it is a radial flow converter, steam is raised within a bayonet tube and effluent is collected in a central pipe. The MRF-Z reactor consists of a single catalyst bed with vertical tubes running through it in a series of concentric circles. (See the sketch of the MRF-Z reactor, below, contained in Figure 1.) Boiler feed water runs through the tubes to remove the reaction heat. Gas enters through the top of the converter and is distributed around the inside of the vessel wall by means of a scalloped distributor at the vessel wall. The gas then passes through a continuous catalyst bed that contains a number of rings of tubes. The tubes are fed with boiler feed water that passes up through the centre of the tube and then passes down through the outer bayonet tube and medium steam is formed by the absorption of the heat of reaction. The cooling tubes in the MRF-Z reactor running through the catalyst bed are of a

bayonet type design to allow for thermal expansion, (fixed tubes in the MRF reactor) (See the sketch of the Layout of MRF-Z , below, contained in Figure 2.

The use of the bayonet tube avoids problems with thermal stresses and allows for free draining. Inspection of the tubes during maintenance is also easy as the inner tube can be withdrawn from the converter. As the temperature of the reacting gas closely follows the maximum rate curve, the catalyst volume for an MRF-Z is less than that for an equivalent quench converter. The benefit of a radial flow converter is that the pressure drop through the catalyst bed is low. The MRF converter can be scaled up to very large sizes (10,000 te/d) by extending the height.



Figure 1. MRF-Z Reactor

Steam Outlet

Central Pipe

Catalyst Loading Gas Inlet

Gas Outlet & Catalyst Unloading

BFW Inlet

Cooling Tube

Catalyst

Inert Balls



Figure 2 – Layout of MRF-Z

Outlet Collector

Scallops Adiabatic Beds Cooled Bed

Cooling Tube

Outer Tube

Inner Tube

Boiler Feed Water

Steam/BFW



4 MRF-Z Advantages and Disadvantages The use of the bayonet tube avoids problems with thermal stresses and allows for free draining. Inspection of the tubes during maintenance is also easy as the inner tube can be withdrawn from the converter. As the temperature of the reacting gas closely follows the maximum rate curve, the catalyst volume for an MRF is less than that for an equivalent quench converter. The benefit of a radial flow converter is that the pressure drop through the catalyst bed is low. The MRF-Z converter can be scaled up to very large sizes (10,000 te/d) by extending the height. Discharge of the catalyst is complex since the central collection pipe has to be removed from the base of the converter. This requires that the converter must be supported on a structure by at least the height of the collector. Toyo have recently come with a solution to this problem, which involves jacking up the central collector and discharging the catalyst by gravitational flow. The catalyst that is left behind is water flushed from the reactor. Natural circulation of the boiler feed water is not possible with the MRF and so circulation pumps are required.

Catalyst LoadingGas Inlet

Gas Outlet & Catalyst Unloading

BFW Inlet Steam Outlet

Cooling Tube

Catalyst

CentralPipe

Inert Balls



5 MRF-Z REACTOR SIZING: 3000 TPD single train Methanol plant LEAN GAS CASE

Bed No. cooling tube htc area Recovered catalyst U A per V number Heat volume kcal/m2/hr/K m2 [10^6kcal/h] MJ/hr/m2/K 1/m

1 50.54 2 230 538.3 587.3 10.84 10.03 2.254 58.55 3 3.13 4 216 562.9 551.6 11 8.96 2.357 61.56 5 2.84 6 198 591.1 505.6 10.14 7.88 2.475 64.16 7 2.54 8 168 610.1 429 8.28 7.32 2.554 58.61 9 2.25 10 150 646.7 383 7.25 6.24 2.708 61.38 11 1.96 12 120 671.9 306.4 5.57 5.69 2.813 53.85 13 1.66 14 102 722.4 260.5 4.75 4.61 3.025 56.51 15 6.03

total 1184 121.68 Bed No. Tin Tout MeOH in MeOH out GBHE Tin GBHE Tout Cat Vol

1 240 272.6 0.51 1.99 240 272.6000508 50.54 50.54 2 272.6 271.9 1.99 2.39 272.6000508 271.7647964 10.03 60.57 3 271.9 275.1 2.39 2.5 271.7647964 275.0004438 3.13 63.7 4 275.1 271.8 2.5 2.81 275.0004438 271.7138833 8.96 72.66 5 271.8 274.3 2.81 2.89 271.7138833 274.2428218 2.84 75.5 6 274.3 269.7 2.89 3.12 274.2428218 269.7105285 7.88 83.38 7 269.7 271.6 3.12 3.19 269.7105285 271.6617645 2.54 85.92 8 271.6 267.8 3.19 3.38 271.6617645 267.8643458 7.32 93.24 9 267.8 269.3 3.38 3.43 267.8643458 269.3881178 2.25 95.49 10 269.3 265.3 3.43 3.57 269.3881178 265.4346864 6.24 101.73 11 265.3 266.5 3.57 3.62 265.4346864 266.6342626 1.96 103.69 12 266.5 263.7 3.62 3.73 266.6342626 263.8237483 5.69 109.38 13 263.7 264.6 3.73 3.77 263.8237483 264.7578334 1.66 111.04 14 264.6 261.9 3.77 3.86 264.7578334 262.0188452 4.61 115.65 15 261.9 264.9 3.86 3.97 262.0188452 265.1159407 6.03 121.68



RICH GAS CASE

Bed No. cooling tube htc area Recovered catalyst U A per V number Heat volume kcal/m2/hr/K m2 [10^6kcal/h] MJ/hr/m2/K 1/m

1 50.54 2 230 536.7 587.3 10.84 10.03 2.247 58.55 3 3.13 4 216 561.2 551.6 11.05 8.96 2.350 61.56 5 2.84 6 198 589.5 505.6 10.17 7.88 2.468 64.16 7 2.54 8 168 608.4 439 8.27 7.32 2.547 59.97 9 2.25

10 150 644.9 383 7.19 6.24 2.700 61.38 11 1.96 12 120 670.1 306.4 5.51 5.69 2.806 53.85 13 1.66 14 102 720.6 260.5 4.68 4.61 3.017 56.51 15 6.03

total 1184 121.68 Bed No. Tin Tout MeOH in MeOH out GBHE Tin GBHE Tout Cat Vol

1 239 272.6 0.51 2.07 239 272.5920792 50.54 50.54 2 272.6 272.1 2.07 2.49 272.5920792 271.8841109 10.03 60.57 3 272.1 275.4 2.49 2.61 271.8841109 275.2483454 3.13 63.7 4 275.4 272 2.61 2.92 275.2483454 271.8589411 8.96 72.66 5 272 274.6 2.92 3.01 271.8589411 274.4589515 2.84 75.5 6 274.6 269.8 3.01 3.24 274.4589515 269.7315257 7.88 83.38 7 269.8 271.7 3.24 3.31 269.7315257 271.719665 2.54 85.92 8 271.7 267.7 3.31 3.49 271.719665 267.5687023 7.32 93.24 9 267.7 269.2 3.49 3.55 267.5687023 269.1104847 2.25 95.49

10 269.2 265.1 3.55 3.69 269.1104847 265.0632932 6.24 101.73 11 265.1 266.3 3.69 3.73 265.0632932 266.2720291 1.96 103.69 12 266.3 263.4 3.73 3.85 266.2720291 263.3967418 5.69 109.38 13 263.4 264.3 3.85 3.88 263.3967418 264.3345795 1.66 111.04 14 264.3 261.5 3.88 3.97 264.3345795 261.5481905 4.61 115.65 15 261.5 264.5 3.97 4.09 261.5481905 264.6429583 6.03 121.68



MUG RECYCLE INCONV EXCONV EX FLASH CRUDE PURGE

CO 2758.448

2653.965

5412.413

2785.628

2782.797

2.831

128.836

CO2 1460.950 2175.108 3636.058 2310.253 2280.696 29.557 105.588 H2 13185.393 81143.701 94329.094 85098.061 85082.769 15.288 3939.069 H2O 43.345 68.735 112.080 1446.489 72.072 1374.417 3.336 CH3OH 0.000 599.693 599.693 4538.472 628.807 3909.664 29.111 CH4 555.177 10912.944 11468.122 11468.129 11442.708 25.422 529.763 N2 161.694 3278.390 3440.084 3440.084 3437.539 2.549 159.149 L.ENDS 0.000 19.701 19.701 23.225 20.656 2.565 0.955 H.ENDS 0.000 0.000 0.000 1.696 0.000 1.696 0.000

TOTAL 18165.010

100852.236

119017.245

111112.032

105748.043

5363.989

4895.807

TEMPERATURE 45 45 239 264 45 45 45 PRESSURE 83 78 83 80 78 78 78

MUG

Recycle

Converter Inlet

Converter Outlet

Separator Overhead

Separator Liquid

Purge CO 2758.45 2711.20 5469.65 2960.37 2842.94 3.04 131.68 CO2 1460.95 2170.55 3631.50 2266.92 2275.99 28.59 105.42 Hydrogen 13185.39 81226.56 94411.95 85299.43 85171.53 13.02 3945.06 H2O 43.34 70.90 114.24 1478.83 74.34 1369.52 3.44 Methanol 0.00 513.79 513.79 4387.66 538.75 3920.19 24.95 Methane 555.18 10871.52 11426.69 11426.69 11399.53 27.16 528.01 Nitrogen 161.69 3279.47 3441.16 3441.16 3438.75 2.41 159.28 Ethanol 0.00 0.08 0.08 0.08 0.08 0.66 0.00 1-Propanol 0.00 0.02 0.02 0.02 0.02 0.26 0.00 1-Butanol 0.00 0.01 0.01 0.01 0.01 0.17 0.00 Acetone 0.00 0.02 0.02 0.02 0.02 0.01 0.00 M-E-Ketone 0.00 0.01 0.01 0.01 0.01 0.01 0.00 M-Formate 0.00 0.41 0.41 0.41 0.43 0.33 0.02 diM-Ether 0.00 7.72 7.72 7.72 8.09 0.57 0.37 Total 18165.00794 100852.24 119017.2479 111269.3119 105750.4922 5365.936357 4898.252152 Temp 140 45 239 265 45 45 45 Pressure 83 78 80.5 80.1 78 78 78



APPENDIX



CALCULATING THE MINIMUM TUBE PITCH OF A MRF-Z REACTOR



acme 3000 tpd methanol plant mrf-z reactor sizing

Technology

maximum rate

reacting gas

lean gas case

boiler feed

gas processing

tin tout meoh

situ sulfiding

minimum tube