![EXPLANATION
• Temperature approach is LMTD, logarithmic mean temperature difference.
• LMTD=[(400-298)-(400-343)]/ln(102/57)]=77.33K; heat capacity water 4200J/kg.K
• 400 K refer to reactor temperature which need to maintain. 298 and 343 K refer to
coolant temperature enter and leave the jacket.](https://image.slidesharecdn.com/aspendynamic-220110032923/85/Aspen-Plus-dynamic-15-320.jpg)
Aspen Plus dynamic
- 1. ASPEN PLUS DYNAMIC KHAIRUL ANWAR MOHAMAD SAID
- 2. INTRODUCTION • It is a process control • ASPEN dynamic simulate a process by running it within a controlled variable • Basic term: • Open loop control: controller output has no feedback from the process itself and manually change by the operator. Controller fixed at a value • Disturbance: uncontrolled changes which affect the process variable • Close loop control: controller output has feedback from the process. • PV: present value, SP: set point, OP: output (controller)
- 3. DESCRIPTION • Ethylbenzene (E) react with benzene (B) to produce desired product ethylbenzene (EB). There is a consecutive reaction that produces the undesirable product diethylbenzene (DEB). The third reaction combine benzene and diethylbenzene to form ethylbenzene 1) 2) 3)
- 4. CONTINUE • In symbolic notation: • k is second order reaction constant (m3/kmol.s). Concentration in mol/l or kmol/m3. Activation energy in kJ/kmol. Temperature in Kelvin.
- 5. CONTINUE • Two feed stream enter the reactor with 0.1 kmol/s ethylene and 0.2 kmol/s benzene. Notice that molar flow rate of benzene is more than its stoichiometric value to maintain low enthylene concentration which minimized DEB formation. DEB is undesired product.
- 6. PROPERTIES ENVIRONMENT • Template “chemical with metric units” and change unit to SI in global
- 7. PROPERTIES ENVIRONMENT • Add m-DEB (m-diethylbenzene) and other chemicals • PSRK as the property method, click next and run the properties.
- 8. SIMULATION ENVIRONMENT • Follow the following process flowsheet
- 9. SIMULATION ENVIRONMENT Setting valve 1 and 2 Setting valve 3 FBO FEO Input all the information by click next Make sure the unit is correct
- 10. • Setup reactor and its reaction. Go to reaction. Click new reaction and use POWERLAW type. SIMULATION ENVIRONMENT
- 11. SIMULATION ENVIRONMENT • You need the kinetic expression for each POWERLAW reaction Notice the value for each POWERLAW reaction came from the above expression
- 12. SIMULATION ENVIRONMENT • Rector setup, the valid phases is liquid only with reactor volume of 60 m3(cum). cum is cubic meter. Associate all the reaction (R1-R3) in RCSTR. • Run the simulator. Check the overall conversion based on ethylene as the limiting reactant (0.1-0.053)/0.1=0.5
- 13. CONVERSION STEADY-STATE TO DYNAMIC MODE • Click the Dynamic tab and turn on Dynamic mode • Once activated, you need to input some dynamic data as follow
- 14. CONVERSION STEADY-STATE TO DYNAMIC MODE • Before running the simulation, change convergence solver from Broyden to Newton. Then run it
- 15. EXPLANATION • Temperature approach is LMTD, logarithmic mean temperature difference. • LMTD=[(400-298)-(400-343)]/ln(102/57)]=77.33K; heat capacity water 4200J/kg.K • 400 K refer to reactor temperature which need to maintain. 298 and 343 K refer to coolant temperature enter and leave the jacket.
- 16. EXPLANATION • Equipment modeled as stainless steel CSTR with mass of Area x thickness x steel density= 320 x 0.005 x 7800 = 12480 kg Steel heat capacity = 500 J/(kg.K)
- 17. EXPLANATION • Q=UA∆T=3.71018x106 W= UA x 77.33 K; UA= 47979 W/K • U=150 W/m2.K from industrial cooler with cold fluid as water and hot fluid as organic solvent*. So, A= 320 m2 • V= π x (D2/4) x L= 60 = π x (D2/4) x 10; D = 2.764 m • Area = πDL=86.83 m2 • Lateral area= 320 = π x 0.1016 x Lcoil ; Lcoil = 3150 m • Lcoil=Nloop x Length single loop = Nloop x π x 0.95 x Dtank ;Nloop=382 • 0.95 for clearance between reactor wall and coil surface • Vertical space for entire loop = 1.25 x 0.1016 x 382 = 48.51 m. • 1.25 clearance factor between one loop and another • Liquid volume fraction= 48.51/10 = 0.485 *https://www.engineersedge.com/thermodynamics/overall_heat_transfer-table.htm
- 18. CONVERSION STEADY-STATE TO DYNAMIC MODE • Go to the Dynamic tab and click Pressure Checker. If the flowsheet fully pressure driven, click Pressure Driven button • Save the file as P Driven simulation with extension of .dynf • A new window will appear Aspen Plus Dynamic
- 19. CONVERSION STEADY-STATE TO DYNAMIC MODE • Notice the level controller RCSTR_LC connected to VALVE3 and RCSTR • Run the simulation in Initialization mode. The run has completed window will appear.
- 20. CONVERSION STEADY-STATE TO DYNAMIC MODE • Run the simulation in steady state then in dynamic mode. Let it run for awhile.
- 21. CONTROLLER FACEPLATE • Click RCSTR_LC and a window will appear. • PV: present value, SP: set point and OP: controller output From left: auto, manual and cascade mode From left: Percentage unit, configure, plot and tune
- 22. OPEN-LOOP (MANUAL MODE) TUNE-UP • Change controller to manual mode • Click the Tune button, choose open loop test method and step down 5%. Click the Tuning Parameter and choose tuning rule Ziegler-Nichols and controller type: PI (proportional and integral) • Open Plot to monitor liquid level • Start Initialization mode then run in Dynamic mode • Continue the test until PV stabilized. You will notice that PV would in the Plot start to adjust toward SP. Click finish test to stop the test
- 23. OPEN-LOOP (MANUAL MODE) TUNE-UP • After the test finish, Tune window will show the estimated control loop characteristic • Go to Tuning parameters, click calculate. You will get value for gain and integral time for PI controller based on Ziegler-Nichols tuning rule
- 24. OPEN-LOOP (MANUAL MODE) TUNE-UP • Stop the dynamic simulation to update the loop characteristic in Configure window and then click update controller. Notice the similarity. • Test the new settings in auto mode and observe the response. To have a better description of the process, it is recommended that the tune-up test is repeated many times at different step up/down.
- 25. THANK YOU