heat exchanger designing using aspen plus

International Journal of Emerging Trends in Engineering and Development Issue 4, Vol.2 (March 2014)

Available online on http://www.rspublication.com/ijeted/ijeted_index.htm ISSN 2249-6149

R S. Publication (rspublication.com), [email protected] Page 357

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ABSTRACT:

Insufficient cooling of process stream indirectly effects in the performance of any chemical

process. So designing, simulation and optimization of Heat exchangers are very important in

most of the chemical engineering process.Now a daysso many softwares exists for heat

exchanger designing, simulation and optimization purposes.Present studyfocus on simulation

of a heat exchanger using Aspen plus software.Two heater blocks are used to decrease the

outlet of hot stream to less than 70F from 140F, using Aspen plus from HCURVE.

Key words:Heat exchanger, Simulation, Aspen Plus, HCURVES.

Corresponding Author: D. Sushmitha

INTRODUCTION:

Business concern continues to simulate chemical process for a better performance. Heat

exchangers are used to transfer heat between a process stream and a utility stream, with a

minimum energy requirement. Some process engineering systems utilize Heat exchanger

network synthesis for controlling the cost of energy for a process.

These are in turn divided into sequential and simultaneous synthesis. These are Evolutionary

design techniques such as pinch design technique, dual temperature techniques, pseudo-pinch

techniques, and block decomposition techniques, as sequential techniques. And simultaneous

techniques are Mathematical Programming techniques based on the continuous and integer

linear programs. They are primarily Mixed Integer Non Linear Programming (MINLP)[2]

Simulation of heat exchangers can also done by artificial neural networks.[12] this project

provides thermal system designs with a artificial neural networks for predicting heat

exchangers behaviour, providing also adaptive characteristics to the model that can be easily

inserted in a closed loop control scheme. Another paper on Modelling and Simulation of the




Heat Transfer Behaviour of a Shell-and-Tube Condenser for aModerately High-Temperature

Heat Pump[13]

The present case study is on simulation of a exchanger using Aspen. These simulation

techniques seek to find the optimal solution without decomposition of theproblem. Under

Aspen there are several other modules especially for exchanger analysis.

Aspen Tasc+ is Combination of the best of Aspen HTFS and Aspen B-JAC with Aspen

Techs New Application for Design, Checking (Rating)and Simulation of Shell and Tube

Heat Exchangers. It Designs the most economical exchanger for your application Easily

plug your shell and tube designs into either of AspenTechs steady-state simulators so you

can accurately evaluate heat exchanger performance in the context of your overall process

Design.For designing of various exchanges especially Aspen EDR (Exchanger Design and

Rating) is used.

ASPEN PLUS SIMULATION:

This review paper along with an case study is done for better understanding of simulation of

an exchanger using aspen soft ware.The data is extracted from the real process to enhance the

existing process in an industry. Due to insufficient cooling of the process stream the

productivity of the distillation unit is decreased. Here we take Processstreams asfuel oil,

saturated water and then utility stream of ethylene glycol are used for Aspen plus simulation

analysis. Open a new file in the Aspen and select heater block from heat exchanger ikon

appeared in the down row besides several ikons like mixed streams, mixers splitters,

separators, exchangers, columns, reactors. Similarly click another heater block and place side

by side in the new file. Naming of the heater blocks as block 1 and 2, and streams as hot feed

in and cold feed in to each block inlet streams respectively.




After completion of flow sheet, we give other information such as run type, property method,

and stream data.Here we userun type as the flow sheet in the global sheet and property

method as Wilson method. Then click next to select the process streams and utility stream in

the flow sheet. After selection of streams then Wilson property method was selected.Next

specifications of the streams like state variables and flow rates of hot as well as cold streams

respectively are given. Inlet temperature of cold streams as 40F and flow rate as 15000 lb/hr.

Fuel oil inlet temperature as 140F and flow rates of fuel oil and saturated water as 200 and

1800lb/hr respectively.

Block specifications given as 70Fis therequired temperature to which the hot stream has to

be reduced below that value. Next specifications for second block is taken as 0 psi

(negligible pressure) for pressure and temperature column is kept blank, return to the process

file and add heat stream between two blocks, with this the specification of the block is

completed.

Check all the given input, on left side of the window, and then click on start to start

simulation. The specified things are highlighted with blue colour in the left side of the

column. As shown below.

The simulation is passed for some time to see the outlet temperature of the cold

stream. Click on the outlet stream of the second heater block a new sheet consisting of the all

the information about that stream is displayed temperature of the cold stream outlet shown is

54.5F.




Heat duty can be seen for the block from results summary, for the first block the heat duty is

-130.048 kcal/hr.

Heat curves can be seen for hot and cold streams, click on the heater block 1 in the flow sheet

a window with all information of heater block 1 will appear.Click on the HCURVE under

block 1, in results. Click on new,to create HCURVES. Then select heat duty in Set up then

click start observe the results. Results consists of point number, status, heat duty pressure,

temperature.

Select the first Column consists of no of points and then go to picture ikon in the top and

select as x-axis, next select the temperature column as y-axis, go to pictures, and then y-

axis.return to the picture add new curve new window will appear with the block 2, select it.

Do same for the second block,HCURVES. Then select display result in the pictures.




The blue line in the plot represents temperature profile of the first heater block and green is

for temperature profile of the second heater block. The temperature range of the y-axis is

increased, so that the accurate temperature range to which hot fluid can have a minimum

temperature i.e from fig it is shown as approximately70-54.5F

.

The objective of this study is to minimize the temperature of the hot stream. By

changing the Specification of the out let temperature of the first block as 54.5F, again heat

curves are drawn (procedure as above), it is shown as 58.5F.




CONCLUSION:

This review has highlighted the importance of simulation using aspen with an

case study. The simulation of an heat exchanger is done on the Aspen. The out let of the cold

stream temperature is found as 54.5F, simulation is done by specifying the temperature of

the hot stream to less than 70F Finally a minimum temperature to which a hot stream can be

brought is 58.5F got from the HCRUVES.

REFERENCE:

[1]. Lang, Jim. Design Procedure for Heat Exchangers on AspenPlus Software Design

manual. June 1999.

[2]. Lang, Jim. Boiling Design on Aspen-Plus. Design manual. July 1999.

[3].Aspen Plus Simulator 10.0-1. User Interface (1998).

[4]. Coulson and Richardson. Chemical Engineering Fluid Flow, Heat Transfer and Mass

Transfer. Volume 1, 5th ed., Butterworth and Heinemann, 1996.

[5]. Geankoplis, Christie J. Transport Processes and Unit Operations, 3rd ed., Prentice

Hall, 1993.

[6]. Incropera and DeWitt. Fundamentals of Heat and Mass Transfer. 4th ed., John Wiley

and Sons, 1996.

[7]. Perry, P.H. and Green, D. Perrys Chemical Engineering Handbook. 7th ed.,

McGraw-Hill Book Co., 1997.

[8] A.M. Law, Simulation Modelling & Analysis (4th Ed.), McGraw-Hill, London, 2007.

[9] Using Simulation Modelling to Improve the Performance of Chemical Engineering .

Processes: Part 1 Industrial Heat Exchanger Network Analysis Int. J. Pure Appl. Sci. .

Technol., 12(1) (2012), pp. 39-48.

[10] P.J. Sanchez, Fundamentals of simulation modelling, Engineering Management Review,. . IEEE,37(2009), 23-23.

[11] Condenser Design on Aspen-Plus Software(Heat Exchanger design with a phase . . . .

.change)Author: Jim Lang (SDSM&T, 2000).

[12] Simulation and control of heat exchangers using artificial neural networks.

[13] Modelling and Simulation of the Heat TransferBehaviour of a Shell-and-Tube.

Condenser for aModerately High-Temperature Heat Pump.

heat exchanger designing using aspen plus

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