Jump Start: Rigorous Shell & Tube Exchanger Sizing in Aspen HYSYS V8

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1 Jump Start: Rigorous Shell & Tube Exchanger Sizing in Aspen HYSYS V8 A Brief Tutorial for Autosizing and Interactive Sizing in Aspen HYSYS V8 Lauren Sittler, Product Management, Aspen Technology, Inc. Tom Ralston, Director, Equipment Design and Rating, Aspen Technology, Inc.

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3 Table of Contents Introduction to Autosizing and Interactive Sizing Scope of this Document Overview of the Example Case Autosizing Sizing the Exchanger Viewing the Results Interactive Sizing Sizing the Exchanger Additional Resources

4 Introduction to Autosizing and Interactive Sizing Aspen HYSYS V8 features streamlined workflows for transforming any simple heat exchanger model in a simulation flowsheet into a rigorous EDR Shell & Tube or Air Cooled model. One click sizes an exchanger using the full design optimization logic of EDR, resulting in a rigorous exchanger model which you can choose to embed in your simulation. You can benefit from a more precise model which will respond to process changes to help you optimize your overall process design and process operations. You can easily view a summary of thermal hydraulic results from the model and even view the exchanger setting plan, tube layout or temperature profiles. These workflows are mainly focused on the preliminary design of heat exchangers where the objective is to rapidly assess the size and cost of exchangers required for a given process duty, including requirements for multiple shells in series and in parallel. Design templates can be used to tailor the design constraints to specific process requirements such as materials of construction, stream fouling resistances, allowable pressure drops and company standards for exchanger head types or shell types. The preliminary designs obtained can be an excellent basis for subsequent detailed thermal and mechanical design of exchangers. Scope of this Document This Jump Start guide will provide step-by-step instructions for completing automatic and interactive sizing in Aspen HYSYS. You will learn how to: Autosize a Shell & Tube exchanger in HYSYS Interactively size a Shell & Tube exchanger in HYSYS We will use an Aspen HYSYS case file to demonstrate the integrated workflows. We have also included an EDR solution case for the final EDR designs. The files associated with this example are available for download on the Customer Support & Training website. Overview of the Example Case Open the case RefSYS CDU for Autosizing in HYSYS. In this case we are modeling a crude refining process. The exchanger that we will design is located in the Preheat Train subflowsheet. In the preheat train the raw crude is heated by a series of exchangers before entering the crude furnace. Our example will focus on exchanger E103. Figure 1. E-103 in the Aspen HYSYS Crude Preheat Train 2

5 Autosizing Sizing the Exchanger 1. Double click on the Preheat Train subflowsheet to open the form. Click the Sub-flowsheet Environment button at the bottom. 2. Locate exchanger E103, immediately downstream of the Desalter. Double-click to open E Click on the Design tab > Connections form. Note that the crude stream from the previous exchanger is the Shell Side Inlet, and the recycled residual stream is the Tube Side Inlet. Let s change this so that our crude stream is on the tube side. Click the Switch Streams button, located in the center of the form below the exchanger diagram. 4.Click on the Parameters form under the Design tab. You can see that the model type is currently a Simple End Point Model. 5. The pre-specified allowable pressure drops for E-103 are unrealistic. Let s increase both shell-side and tube-side values to 0.5 bar (50kPa). A reasonable pressure drop allowance is essential for realistic sizing of exchangers. If you find that the design requires multiple shells in series it is always worth considering allowing more pressure drop to see if that results in a cheaper optimum design. 6. We are now ready to run the automatic sizing. Click on the Size Rigorous Shell & Tube button at the bottom of the form. The EDR progress bar will display, indicating that designs are being evaluated to identify which are feasible. You will see a numerical read out of the designs being explored. When optimization is complete, results will be updated to the Aspen HYSYS exchanger Parameters form. Note: You may see a pop-up message asking if you wish to override existing outlet stream specifications with the outlet stream conditions calculated by EDR. This occurs because, in this case, temperature was a user-specified variable. When we transitioned from a simple end point model to a rigorous model we can calculate the outlet temperature of both streams. Click Yes to accept this new definition for the outlet temperature. 3

6 Figure 2. Heat Exchanger: E103 Parameters Form after Sizing Viewing the Results You have now completed autosizing this exchanger and your simple End Point model has been replaced by a rigorous EDR model. You can see some of the results in the Rigorous Model section at the bottom of the form. You can see that we now have values for the Effective Surface Area, and Overall Heat Transfer Coefficient. In this case there is an indication of a vibration risk in this exchanger. To view more exchanger details click on the Rigorous Shell & Tube tab at the top right of the form. Click on Exchanger in the vertical form list. Here you can see that we have a BEM TEMA-type exchanger, with 1 shell, 589 tubes in one tube pass and a 30-Triangular Tube Pattern. The geometry specifications that are italic blue, such as the TEMA type and tube pattern, are EDR defaults. These configuration defaults may not be appropriate for this crude pre-heat application. We can elect to use an EDR Design Template file to customize the Auto-sizing constraints specifically for our process. Checking the box marked Select a Design Template File in Figure 2 above will open a dialogue where we can browse to a suitable template file (designated: filename.edt) In interactive sizing we will see how to adjust key constraints before running Sizing. Scroll through the forms in the Rigorous Shell & Tube tab to view more information about the Process, Results Summary, Setting Plan, and etc. To view full details of the design, click on the Model Details button at the bottom of the form. The full EDR Shell & Tube User Interface can be accessed. You will see that the model is in Simulation mode. Any changes you make to your model will cause Aspen HYSYS to re-solve. 4

7 Figure 3. Rigorous Shell & Tube Exchanger Results Interactive Sizing Sizing the Exchanger Interactive sizing allows greater flexibility than autosizing. In this mode you can adjust design constraints before the initial sizing and you can explore the effects of changing constraints on the optimum design found. Interactive sizing uses the EDR Sizing Console to allow you to adjust some key geometric and process design constraints. You can adjust your settings and view summary sizing results in this environment. You can save your design at any stage as an EDR file, accept the most recent design and revert to your simulation, open a template or an initial EDR file prepared with your required design constraints or choose to cancel your sizing process and revert to your simple model in Aspen HYSYS. 5

8 To interactively size the exchanger complete steps 1-5 for autosizing, listed above, and then follow the steps below. Figure 4. Interactive Size Rigorous Shell & Tube 1. On the Design tab> Parameters Form you will notice that the Size Rigorous Shell & Tube button has a dropdown arrow on the right size. Click on the dropdown arrow and choose Interactive Size Rigorous Shell & Tube. The EDR Sizing Console appears. 2. The console has four tabs: Geometry, Process, Errors & Warnings, and Run Status. The Geometry tab contains a summary of the exchanger design specifications and constraints. The Process tab lists the process stream conditions and key process constraints. We will make all of our changes on these two tabs, starting with Geometry. If you wanted to view all of the user-input you could click on the Full EDR Browser button on the top right. This will expand the navigation pane to show all folders. For now, click on the Geometry tab and make the following adjustments for this crude process exchanger: Change the TEMA type to AET The Tube pattern to 45-Rotated Square The Baffle cut orientation to vertical 6

9 Figure 5. Set Geometry Specifications Click on the Process tab. Set the fouling resistance to hf/btu for both the Hotside and the Coldside Return to the Geometry tab. Figure 6. Set Process Specifications 7

10 3. Click the Size Exchanger button to run the sizing optimization. 4.After the sizing is complete, we can review the overall results on the Geometry tab. If we compare our new design (Most Recent Run) with the previous one, we see that by changing the TEMA type for easier cleaning, and inputting a realistic fouling factor, we require a larger diameter shell and our exchanger cost has increased. We now have an exchanger configuration which is better suited to our crude-pre heat application. Figure 7. EDR Interactive Sizing Results 5. You can continue adjusting this design by changing parameters and re-sizing until you are satisfied. If you choose to Accept Design you will return to Aspen HYSYS with a rigorous exchanger model inside your simulation. If you select Cancel we can return to the Aspen HYSYS simulation and revert to the simple model. 8

11 Additional Resources Check out other training materials specifically for this product: Public Website Online Training Video Tutorials Autosizing Shell & Tube Exchangers in Aspen HYSYS V8 New Interactive Sizing in Aspen Plus Jump Start Tutorial Getting Started in Aspen Shell & Tube Exchanger V8 Jump Start: Rigorous Sell & Tube Sizing in Aspen Plus Help Menu 9

12 About AspenTech AspenTech is a leading supplier of software that optimizes process manufacturing for energy, chemicals, engineering and construction, and other industries that manufacture and produce products from a chemical process. With integrated aspenone solutions, process manufacturers can implement best practices for optimizing their engineering, manufacturing, and supply chain operations. As a result, AspenTech customers are better able to increase capacity, improve margins, reduce costs, and become more energy efficient. To see how the world s leading process manufacturers rely on AspenTech to achieve their operational excellence goals, visit Worldwide Headquarters Aspen Technology, Inc. 200 Wheeler Road Burlington, MA United States phone: fax: info@aspentech.com 2013 Aspen Technology, Inc. AspenTech, aspenone, the Aspen leaf logo, the aspenone logo, and OPTIMIZE are trademarks of Aspen Technology, Inc. All rights reserved Regional Headquarters Houston, TX USA phone: São Paulo Brazil phone: Reading United Kingdom phone: +44 (0) Singapore Republic of Singapore phone: Manama Bahrain phone: For a complete list of offices, please visit