OLI Simulation Conference 2014

Transcription

1 OLI Simulation Conference 2014 Process Safety Study Using Aspen/OLI Inadvertent Mixing of Electrolyte Raw Materials In Storage Tanks David Kolesar The Dow Chemical Company October 2014 TM The DOW Diamond is a Trademark of The Dow Chemical Company ( Dow ) or an affiliated company of Dow.

2 Background / Objective We All Know What Happens If Sulfuric Acid Accidentally Gets Pumped Into A Caustic Tank. But What Happens If, Say, Methacrylic Acid Were Pumped Into An Aqueous Ammonia Tank (Weak Acids and Bases). These Are Just The Questions That Dow Process Safety Was Looking Into And Needed A Means To Evaluate Them. Decision Was Made To Build A Dynamic Simulation.

3 Initial Modeling Attempt With Aspen Dynamics

4 Initial Modeling Attempt With Aspen Dynamics Worked Well But Many Components and Chemistry Were Missing

5 Next Attempt: Aspen Dynamics With OLI Chemistry & Properties

6 Dynamic Results of Methacrylic Acid into Ammonia Tank

7 With Many Tanks to Evaluate Needed A Tool for the Non-Modeler - Aspen Simulation Workbook - Many, Many Plants and Tanks (100 s) To run But, Not Good Use of Modeler s Time The plan - Embed the Aspen Dynamics Flowsheet In Aspen Simulation Workbook (Excel Interface For Aspen Simulators) Provides Tool for Process Safety Personnel to Use And Run A Multitude Of Cases

8 Aspen Simulation Workbook

9 Input Table

10 Input Table

11 How Do You Prevent Pairs With No Chemistry?

12 How Do You Prevent Pairs With No Chemistry? ---Conditional Drop Downs---

13 How Do You Prevent Pairs With No Chemistry? ---Conditional Drop Downs---

14 Tabular Output

15 ASW Graphic Output

16 ASW Graphic Output

17 Works Great But The Aspen Dynamic Simulation in ASW Ran Well But... When Change Starting Conditions in the Tank (i.e. Temperature, Pressure, Composition), The Simulation Would Not Initialize or Became Infeasible. Stable in Aspen Plus But Not Aspen Dynamics with OLI Properties. Next Plan: Run Simulation In Aspen Plus With A Sensitivity Clock

18 What Is A Sensitivity Clock? Means To Emulate Dynamic Behavior Using Aspen Plus Steady State Simulator using a Sensitivity Block Uses: Sensitivity Block Transfer Block Sequence Block

19 How Does The Sensitivity Block Clock Work? In The Sensitivity Block, A Dummy Variable Is Created and Incremented to Model Time. Each Pass of the Sensitivity Block Represents a Time Step. The Value of the Time Step Is Either Determined By the Intrinsic Residence Time or Characteristics of the System or User Determined if Less Restrictive Than System Requirement. As with Any Sensitivity Block, You Need to Store the Data You Want to Keep From Each Run.

20 Transfer Blocks At the End of Each Pass of the Sensitivity Block, Selected Output from the Simulation Is Transferred To the Input Via Transfer Blocks. With the Output now the Input, the Simulation Is Ready to Begin The Next Time Step.

21 Aspen Plus Flowsheet With Sensitivity Clock 1. Initial Tank Volume (First Pass) 3. Pressure if No Venting 5. Tank w Actual Relief 6. Tank Contents At End Of Time Step Transfer Blocks 4. Relief Capacity Calculations 2. Truck Unloading

22 Results of Acrylic Acid Into A Potassium Hydroxide Tank

23 Results of An Amine Pumped Into A Methacrylic Acid Tank S-1 - Results Summary TANKM TANKT RDFLOW RVFLOW VRVFLOW GOOSEFLO PTANK TOTTOATM LB/HR F PSIA Y4 Axis label VARY 1 PARAM 10

24 Acknowledgement / Recognition Dow Colleagues: Dung Thi Vu Zak Kivitz OLI: AJ Gerbino Pat McKenzie Jim Berthold Jerzy J. Kosinski

25 Thank You Questions?