CHEMICAL ENGINEERING 422 SIMULATION WITH HYSYSThis year we have two packages available from Hyprotech Ltd. • • HYSYS 2.4.1: This package simulates chemical plants operating under both steady state and dynamic conditions. HX-Net 5.0: This is used for designing heat exchanger networks. In this exercise you will learn the basics of HYSYS.Plant when it is operating in steady-state mode. We will introduce the software by performing a simple exercise. You will then have a more complicated assignment that you may do in teams of two. NOTES: 1. 2. 3. Simulate the process one unit at a time. Refer to the online help and the online documentation when needed. The words “click on” mean left click the mouse button. THE EXAMPLE: Flashing of Ethanol from Oleic Acid, Sensitivity Analysis and Meeting Recovery Criteria BACKGROUND: Oleic acid is a “friendly” fluid to extract ethanol from a microbial fermentation process. This is a good thing, since the ethanol can be recovered by a flash process from the oleic acid rather than having to distill the fermentation beer. Distillation (boiling off of all that water) is an expensive proposition making ethanol fermentation to produce cheap gasohol not very feasible (still OK for expensive liquors though). In this example we will use HYSYS.Plant to flash ethanol from oleic acid. We first heat the high-pressure ethanol/oleic acid mixture in a heat exchanger and then flash it in an adiabatic flash tank. This process is shown in Figure 1. Figure 1: The Ethanol/Oleic Acid Flash Process 1 Do the same thing for oleic acid. Once you have selected EuroSI. 3. components etc. This will bring you to the Simulation Basis Manager. 7. You should now set up your simulation preferences (eg units). A turquoise PFD screen will now appear – this is where you construct the PFD. We will use EuroSI for this simulation.) We are now ready to simulate the process. You should be back in the startup form. HYSYS calls this a Property Package. 8. Select PRSV (which is a modification of the Peng-Robinson EOS).Plant 1. We need ethanol and oleic acid. and suggests which package you should use. Figure 2: Simulation Basis Manager 2 . To do this click on the Components tab. This should bring up Ethanol in the window below. 6.PROCEDURE: A: Startup of HYSYS. Type ethanol in the Match window. This will bring up the Session Preferences window.). Figure 3) Now. 2. We now need to select the thermodynamics that we will be using. Note: You can have a customized set of units but you must first Clone the unit set (See help files for procedure). This will bring up the startup form. You will see a list of thermodynamic packages. When you select a package HYSYS either approves (there is no action) or disapproves your choice. Once you have your preferences set you can save them to H:\ and load them in each time you use HYSYS. Go to the START button and then to HYSYS. Now chose File:New:Case. 9. There’s a description of them in the HYSYS help files. Make sure Ethanol is highlighted and click the Add Pure button. You can now close or minimize this window. Close the window. and select Equation of State as the EOS Enthalpy Method Specification. To do this we must Enter the Simulation Environment (in the Simulation Basis Manager window). (NOTE: If the process incorporated chemical reactions you would have had to specify a reaction set under the Rxns tab. To do this click on Tools: Preferences. NOTE: You can completely customize HYSYS (not just units) using Preferences. In the Session Preferences window click on the Variables tab. 4. 5. (See Figure 2. Here you will have to Add a Fluid Package (EOS. So click on the Prop Pkg tab. you should first add the chemicals that we will be dealing with. The button containing the red and blue straight lines at the top of the screen should be depressed. Figure 4: PFD HYSYS Window.Figure 3: Fluid Package Window Showing Property Package Tab B: Constucting the Process You should now have a turquoise screen in front of you (Figure 4). indicating that we are in steady state mode. 3 . We want to take a mixture of ethanol and oleic acid and flash it to separate the two components. and two outlet streams. So we will need an inlet stream (containing the mixture to be flashed). a heater or heat exchanger. this is the PFD screen. a flash tank or vessel. A floating window will pop up that displays the stream number. 2. they will all be <empty>. This contains symbols for the unit operations and. so click on the blue arrow. pressure. 6. We will place stream 110 (renumber it to this) close to the heater. let’s change it to “100”. Now move the cursor into the turquoise PFD window and click over the area that you want to place the stream. and flow rate. and place it on the PFD close to the stream 100. We also need an outlet stream. You can also renumber the stream here. Figure 5: Material Stream Worksheet. A light blue arrow labeled “1” should appear. We will now add a heater to preheat the mixture before the flash.The Inlet Stream 1. Set the Temperature to 30 oC. temperature. Pressure to 10 bar. 5. Select the heater icon from the Case (Main) window. material (blue arrow) and energy (red arrow) streams. To specify what is contained in a stream or in a unit operation you can right click on the object and select View Properties. 3. Set the Mole Fraction Ethanol to 0. and the Molar Flow to 100 kgmol/hr. This means that it calculates whatever it can (in the process) each time something new is entered.1 and the balance as Oleic Acid. 4. This arrow will turn a darker blue when it is completely specified or solved. (Another window will pop up for you to enter this data as soon as you try and enter the data into the screen in front of you.) Once you have done this a green bar at the bottom will tell you that everything is OK. If you want to enter several pieces of data you should click on the Solver Holding button (red light) at the top of the screen. Right click on stream 1 and select View Properties. HYSYS is a non-sequential modular simulator. 2. On the right side of the screen you will see a window called Case (Main) (see Figure 4). We also need to set the Composition (so click on the word). 4 . Incompletely Specified Adding a Heater 1. The Solver Active button (green light) will restart your calculations. If you click on Conditions you will see that all other stream conditions have been calculated for you. We need a material stream. we need to set the stream Conditions. Hold the cursor over the material stream. A worksheet window will pop up (Figure 5). 6. telling us that the heat exchanger is correctly specified (and energy stream Q-100 has also been calculated). 4. The red box at the bottom should say “Requires an energy stream. To do this right click over the vessel.93 bar. We now need to add the flash. Right click on the heater and select View Properties (Figure 6). and place it on the PFD. Connect this to the heater.3.” To specify this click on the Worksheet tab. This will bring up a spreadsheet that allows us to change the parameters that are blue. The heat exchanger window now displays a green box at the bottom. 2. We need to connect some streams to the heater.95 bar). Add two material streams (120 – tops and 130 – bottoms) for the outlet of the flash. with a temperature of 105 oC. The flash is now specified correctly – except for the fact that there is no top product. Notice how HYSYS calculates all other parameters (automatically – as they are dependent upon these state variables).95 bar in stream 110. Select PFD ->Auto Position All from the menus at the top of the HYSYS menu. Select the Separator symbol from the Case (Main) window. You should now have both a top and bottom product. 1. You will notice that the heater is red. 5 . HYSYS will add an energy stream called Q-100 to the PFD.” We need to place an energy stream on the PFD and connect it to the heater. This is done in the Design tab. HYSYS now tells us (in the yellow box at the bottom of the heater window) that we have an “Unknown Delta P. We will let the pressure drop to 9. but first we will “straighten up” the PFD. 3. NOTE: Be careful using this when you have a complex PFD. We will set the pressure drop to 9. click on Parameters and set Delta P to 9. 5. 4. Select stream 100 as the inlet and stream 110 as the outlet to the heater. We must set the pressure drop in the flash. this is because it is not completely specified. select View Properties.93 bar (the inlet stream is at 9. Connect the material streams to the flash. Figure 6: Heater Worksheet Adding the Flash To do this we follow a similar procedure as we did for the heater. To meet the design specification we can change one or more variables in the simulation and examine the output of the variable we are interested in. In the case studies window we tell HYSYS that we want to Add a case study.2 kgmol/h) of ethanol.002 kmol/s (7. select the vapour stream. and finally click on OK. Enter a Low Bound (9.949). After clicking on Insert the Variable Navigator window should appear. To perform a case study follow this procedure. Click on Vessel Pressure Drop and then on OK. To do this we will change the pressure in the flash tank and observe the flowrate of ethanol. For example. Select Ethanol in the Variable Specifics column. 2. We now have to select the independent (Vessel Pressure Drop) and dependent (Comp Molar Flow (ethanol)) variables.001 bar) for the vessel pressure drop. You have just added the vessel pressure drop as a variable in the databook. Now. Figure 7: The Databook used in the Case Study 6 . Click on Start to begin the calculations. so we click on that the its number in the Object column. We now have to tell which variable we want to vary. and Step Size (0.e. We want to vary the vessel pressure drop and see how the composition of the vapour stream leaving the vessel varies. NOTE: with two independent variables you will get a 3-D graph. You can display the results as a table or as a graph (Figure 8). 3. You should see the Databook window. High Bound (9. we would like to operate the flash process so that it just produces 0. for example a certain mole fraction of a component in a given stream. We now have to Insert the variables (Variables tab) that we would like to examine. ranges of variables) select View to bring up the Case Studies Setup window. 1. Now Close the window. We are looking at the flash tank.C: Performing A Case Study Often we are required to meet some design specification. In the Tools menu select Databook (Figure 7).8). Use the Insert button and in the Object column. To set up the case study (i. Click on the Case Studies tab. this is where we add the variables. select the Comp Molar Flow in the Variable column. This will select mole fraction of ethanol in the vapour stream as a variable. You will see a list of Variable(s). 87 bar for our product to meet a specification of 7. Change the value in the Vessel Pressure Drop (blue text) to 9. Can we get a more exact estimate of the pressure drop that will provide us with the appropriate product spec? We can “manually” calculate this in HYSYS using the Databook again.Figure 8: Results of the Case Study (Comp Molar Flow Ethanol (kgmol/h) vs Vessel Pressure Drop (bar)) D: Given a Product Specification. Figure 9: Databook Showing the Process Data Tables Tab 7 . 1. Adjust the Vessel pressure drop until the desired molar flow rate of ethanol is achieved. 4. Make sure that the boxes beneath the word Show have “X” marks in them and. with ProcData1 highlighted click on View. 2. In the Databook click on the Process Data Tables tab. A window called ProcData1 Data will appear. You will see that the Comp Molar Flow (Ethanol) changes.2 kgmol/h ethanol. Click on the Add button to add the Vessel Pressure Drop and Comp Molar Flow (Ethanol) to the “Process Data Table”. that is called ProcData1 by default. 3.86. 5. How do we determine the Exact Operating Pressure of the Flash? From the case study we know that the pressure drop should be approximately 9. and go to File: Print Window Snapshot.E: Generating a Report When we require a hardcopy of the data that has been generated. Make sure Materials Streams is highlighted in Setup – Workbook Tabs subwindow. 1. Then name the report what you want. right click on the PFD background. Then click on Add to incorporate this data in the report. you should have only one. 6. We now have to insert the data into the report. Now in the Setup window. 5. right click on the PFD background. 8 . perform the following. Now click on Done – we are finished. You then should View a workbook. use the Add (RHS of window) button in the Variables subwindow to select the variables that should be tabulated on the PFD. 4. 2. Note: You can change the any of the colours that HYSYS uses in the Preferences menu item: Tools: Preferences: Resources: Colors. Figure 10 is a graphic of this procedure. NOTE: You can also instantly generate a report for any or all of streams and/or unit ops by right clicking on the stream/unit op of interest and selecting Print Data Sheet. and you will see this option C) To print a window snapshot. Then select the Workbook: Setup menu. Select Tools: Reports. 2. Select Materials Streams (the one you have modified). We can now Print the report via the Report Builder window. make sure that the PFD is the active window. This is done by selecting Tools: Workbooks. 3. You should first select what you want the table to contain. 4. To select a particular stream or unit click on it in the Objects column. To place the stream table on the PFD right click on the PFD and select Add Workbook Table. The Report Builder window should pop up. we need to generate a Report in HYSYS. F: Printing the PFD Before you print the PFD we would like to add a stream table to it. Select Comp Molar Flow (All conponents). 7. A) To print to a dxf (AutoCAD) file. 3. We then need to Create the report. and a stream table appears on the PFD (Figure 11) To actually print the PFD we have several options. Click on OK. 1. To do this. Click on Insert Datasheet. you will see this option B) To print directly to a printer. Figure 10: Setting Up the Workbook for Inclusion in the PFD Figure 11: The Final Result (Default colours have been changed) 9 .