using petro-sim to optimize an fccu with integrated...

PROPRIETARY INFORMATION© 2014 KBC Advanced Technologies plc. All Rights Reserved.

Using Petro-SIM to Optimize an FCCU

with Integrated Product Separation

Gregory Tragitt – Senior Staff Consultant

May 2014

PROPRIETARY INFORMATIONPROPRIETARY INFORMATION

Biography

2

• 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

KBC Advanced

Technologies Inc.

15021 Katy Freeway

Suite 600

Houston, TX 77094

Tel +1 281 293 8200

Dir +1 281 597 7964

Fax +1 281 616 0900

[email protected]


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

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Background

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• 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


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

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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

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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

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FCC-SIM within Petro-SIM

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Gas Plant

Feed Preheat

FCC

Fractionator Sub FlowsheetWet Gas Compression

Air Blower


Feed Preheat with Reactor and Regenerator

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Heat Streams from Main Fractionator Are Utilized to Preheat the FCC Charge


Main Fractionator

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Tray to Tray Fractionator Is Modeled in a Sub Flowsheet

with Four Pumparound Circuits


Main Fractionator Details

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Unstipped LCO Is

Utilized as Lean Oil for

the Secondary

Absorber and Rich Oil

Is Returned to Tray 7

LCO Is Steam

Stripped


Wet Gas Compression

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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 2nd Stage

Discharge Pressure


Gas Plant

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The Gas Plant includes 2

Absorbers, a Stripper and

a Debutanizer

Heat from the

LCO

Pumparound

Reboils the

Stripper

Heat from the

HCO

Pumparound

Reboils the

Debutanizer


Primary Absorber Details

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Intercoolers

Improve LPG

Recovery


Debutanizer Details

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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


Debutanizer Tray Sizing Utility

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Stream Pricing

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Gasoline Stream Value

Is Priced Based Upon

Road Octane and RVP


Optimizer independent Variables

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Independent Variables:

• Riser Outlet Temperature

• ECAT Activity

• Riser Feed Temperature

• Compression Power

• Fresh Feed Rate

• Debutanizer Bottoms RVP

• Main Fractionator Overhead Product D86 T90


Optimizer Constraints

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Constraints include:

• Fresh Catalyst Addition Rate

• HCO Heat flow to a Steam Generator

• Air Blower Power

• Debutanizer Tray Flooding


Objective Function

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Profit prior to Optimization

Profit After Optimization


Optimized Solution

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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


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

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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

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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

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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

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Economics

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•A Significant Increase in Daily Net Profit Was Determined by the Optimizer

•Notice Utility Costs Are insignificant Relative to Yield Impacts


Key FCC Parameters

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FCC Feed

Increased

Volumetric

Conversion

Decreased

Air Rate

Increased

Regenerator

Temperature

Decreased


FCC Gasoline

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The Optimizer Increased the RVP of the FCC Gasoline

Gasoline Volumetric Rate Increased with Increased Fresh Feed to the FCC


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

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Q&A

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