Using Petro-SIM to Optimize an FCCU with Integrated Product Separation. Gregory Tragitt Senior Staff Consultant

Transcription

1 Using Petro-SIM to Optimize an FCCU with Integrated Product Separation Gregory Tragitt Senior Staff Consultant 2014 KBC Advanced PROPRIETARY Technologies plc. INFORMATION All Rights Reserved. May 2014

2 Biography KBC Advanced Technologies Inc Katy Freeway Suite 600 Houston, TX Tel Dir Fax Gregory Tragitt Senior Staff Consultant, KBC Advanced Technologies BE in Chemical Engineering, Vanderbilt University Marathon Oil Company Sun Petroleum Products Company Champlin Petroleum Company Sun Refining and Marketing Company Kerr McGee Refining Corporation 2

3 Summary Utilizing FCC-SIM within Petro-SIM Can Include Adequate Complexity to Optimize the Reactor and Regenerator together with the Product Separation Equipment and Utility Requirements Utilize Reactor and Regenerator Simulation Tray to Tray Fractionation Compression Utility Constraints FCC-SIM Can Optimize the Reactor and Regenerator with Simplified Fractionation A FCC Model Can Not Determine Parameters Such as Tray Flooding A FCC Model Can Not Determine LPG Recovery Changes with Operating Variable Changes in the Product Separation Equipment A Flowsheet Can Optimize Fractionation FCC-SIM Is Needed to Optimize the Fractionation together with the Reactor and Regenerator The LP Does Not Have Sufficient Detail to Optimize the FCC together with Product Separation that includes Utility Constraints The LP Is Required to Determine Feed and Product Pricing 3

4 Background Energy Conservation initiatives Have Generated Interest in Evaluation of FCC Utility Costs FCC Coke Is Produced as Hydrocarbon Is Cracked in the Riser Coke Is Burned within the Catalyst Regenerator. The Heat Generated from Combustion of Coke - Supplies Heat for Heating the Feed Vaporizing the Feed Reaction Requirements - Energy Is Recovered from the Flue Gas Steam Generation Turbo Expander Incentive Is to Optimize Reactions Rather than to Minimize Coke - Increasing Severity Typically Increases Coke - Increasing Severity Typically Is Economically Desirable Coke Will Generally Be Limited By Regeneration Capacity 4

5 Background Continued Modern FCC Units Have Significant Integration of Utilities Reactor Effluent Has Significant Superheat - Superheat Is Removed in the Bottom Fractionator Pumparound - Additional Pumparounds Remove the Heat of Vaporization from the Cracked Products - Feed Is Typically Preheated from the Energy Recovered from the Fractionator - Gas Plant Heat Requirements Can Generally Be Met from Recovering Energy form Fractionator Integration of Energy Can Constrain the Feed Temperature and Separation Quality Very Little Heat Is Required from External Sources Major Energy Requirements Are for Compression - Air Blower - Wet Gas Compressor Catalyst Cost Is a Significant Unit Expense That Can Impact Energy 5

6 FCC-SIM FCC-SIM Can Effectively Model the Reactor and Regenerator Operation Feed Qualities Feed Rate Operating Conditions Catalyst Quality Product Quality Product Fractionation The FCC-SIM Optimizer Can Optimize the Independent Variables within the Reactor, Regenerator and Cut Points in the Fractionator 6

7 Petro-SIM Additional Parameters Can Be Modeled by Integrating FCC-SIM within Petro-SIM Detailed Fractionation Integrate Recovered Heat from the Fractionator - Preheat Reactor Charge - Reboil Gas Plant Fractionation - Evaluate Compression Energy Stream Pricing Is More Flexible Within Petro-SIM Optimizer Can Be Customized - Include More Independent Variables - Include More Constraints - Objective Function Derived from Stream, Catalyst and Utility Pricing 7

8 FCC-SIM within Petro-SIM Fractionator Sub Flowsheet Air Blower Wet Gas Compression Gas Plant FCC Feed Preheat 8

9 Feed Preheat with Reactor and Regenerator Heat Streams from Main Fractionator Are Utilized to Preheat the FCC Charge 9

10 Main Fractionator Tray to Tray Fractionator Is Modeled in a Sub Flowsheet with Four Pumparound Circuits 10

11 Main Fractionator Details Unstipped LCO Is Utilized as Lean Oil for the Secondary Absorber and Rich Oil Is Returned to Tray 7 LCO Is Steam Stripped 11

12 Wet Gas Compression A Spreadsheet within Petro-SIM Divides the Total Compression Horsepower to Ensure Each Compressor Stage Power Input Is Equal The Total Power Is an independent Variable That Determines the 2 nd Stage Discharge Pressure 12

13 Gas Plant Heat from the LCO Pumparound Reboils the Stripper The Gas Plant includes 2 Absorbers, a Stripper and a Debutanizer Heat from the HCO Pumparound Reboils the Debutanizer 13

14 Primary Absorber Details Intercoolers Improve LPG Recovery 14

15 Debutanizer Details A Heat Exchanger Model Was Utilized for Debutanizer Feed/Bottoms Heat Transfer Heat Exchanger Models Could Have Been Utilized for Transferring Main Fractionator Heat Rather than Simple Heaters with integrated Energy Streams 15

16 Debutanizer Tray Sizing Utility 16

17 Stream Pricing Gasoline Stream Value Is Priced Based Upon Road Octane and RVP 17

18 Optimizer independent Variables Independent Variables: Riser Outlet Temperature ECAT Activity Riser Feed Temperature Compression Power Fresh Feed Rate Debutanizer Bottoms RVP Main Fractionator Overhead Product D86 T90 18

19 Optimizer Constraints Constraints include: Fresh Catalyst Addition Rate HCO Heat flow to a Steam Generator Air Blower Power Debutanizer Tray Flooding 19

20 Objective Function Profit prior to Optimization Profit After Optimization 20

21 Optimized Solution Notice the Optimized Solution Is Against Multiple Constraints: Riser Outlet Temperature at Minimum ECAT MAT at Minimum Riser Feed Temperature at Minimum Feed Rate at Maximum Reid Vapor Pressure at Maximum 21

22 Reporting Workbook Petro-SIM Can Generate a Custom Excel Workbook to Review the Results of Successive Petro-SIM Cases Uses Wizard to Set Options to Generate the Workbook Rapid Configuration and Generation A Reporting Workbook Allows the Differences Between the Case Prior to Optimization to Be Easily Compared with the Case After Optimization A Reporting Workbook Was Generated from the Petro-SIM Flowsheet to Analyze the Optimization Results 22

23 Results The Debutanizer Was Close to Flooding Limits Prior to Optimization Increase in RVP - Decreased Flooding Propensity - Decreased Reboiler Energy Requirements At Constant Debutanizer Feed Rate - Allowed Increase in Debutanizer Feed Available from Increased Fresh Charge Rate - Economics often Favor Lower RVP Heat Availability Little Excess Heat Was Available to Reboil Fractionators and to Preheat the Riser Charge Prior to Optimization Ensure Positive Heat Flow from the HCO Pumparound to a Steam Generator 23

24 Results Continued With Unit Near Existing Constraints It Was Not Obvious How to Increase Charge Rate Feed and Product Pricing Determine Optimum Charge Rate vs Severity at Constraints LP Or Refinery Flowhseet Required to Determine Feed and Product Pricing LCO Product Price Slightly Higher than FCC Gasoline Price Optimizer Did Not Significantly Decrease FCC Gasoline D86 T90 to Produce More LCO Decrease in Gasoline Cutpoint Increases Wet Gas Rate to Compressor - Wet Gas Compression Horsepower Determines Discharge Pressure - Increase in Wet Gas Rate May Reduce the Discharge Pressure to Ensure that the Driver Energy Is within a Constraint - Decrease in Discharge Pressure Will Reduce LPG Recovery 24

25 Results Continued Riser Outlet Temperature An Increase in ROT Is Generally Profitable An Increase in ROT May Increase Gasoline Yield An Increase in ROT Usually Increases C3+ Yield Debutanizer Constraints May Limit Gasoline Production ROT Reduction May Allow Additional Charge Rate to FCC ROT Reduction Will Typically Reduce Heat Input to the Fractionator Catalyst Activity Increased Activity Provides Most Selective Yields Increased Activity Generally Most Profitable Economics May Favor Reduction in Activity to Reduce Vol % Gasoline Yield to Allow More FCC Charge Due to a Debutanizer Limit Lower Activity Will Reduce Coke Selectivity With Regenerator Limits - Increased Catalyst Activity Is the Most Desirable Means to Increase Severity 25

26 Economics A Significant Increase in Daily Net Profit Was Determined by the Optimizer Notice Utility Costs Are insignificant Relative to Yield Impacts 26

27 Key FCC Parameters FCC Feed Increased Air Rate Increased Regenerator Temperature Decreased Volumetric Conversion Decreased 27

28 FCC Gasoline The Optimizer Increased the RVP of the FCC Gasoline Gasoline Volumetric Rate Increased with Increased Fresh Feed to the FCC 28

29 Conclusions The Optimizer Found Significant Profit Although the Unit Was Near Constraints Prior to Optimization The Optimum Solution Was Not Readily Apparent The Optimum Solution Required Significant Rigor in Configuration of the Simulation The Optimized Solution Included Moves that Are Not Typically Believed to Be the Most Desirable The Optimized Solution Requires Valid Pricing The Solution Can Change as Prices Change A Rigorous Model Will Supplement Significant Experience 29

30 Q&A 30