Distillation Column Flooding Predictor Texas Technology Showcase

Transcription

1 Distillation Column Flooding Predictor Texas Techlogy Showcase Galveston, Texas 2006 George E. Dzyacky 2ndpoint LLC

2 Developer George E. Dzyacky (da ZA key) Background in Refining Operations 28 years Petroleum Refining FCC and Vapor Recovery Received Amoco Whiting Refinery highest recognition award three times for advanced process control invations, totaling $6.8MM (US) /year Patent holder Twice awarded U. S. Department of Energy grant on Flooding Predictor

3 Techlogy description Flooding Predictor was developed as a diagstic tool to predict and avoid chronic flooding in FCC absorber columns evolved into A/C strategy Exploits patterns of behavior that column variables undergo as liquid begins to hold-up Highly repeatable patterns were discovered to precede flooding events When pre-flood conditions are detected, the strategy generates a warning of impending flood or a discrete output to temporarily reduce operating severity 98%-plus accuracy increased confidence in the methodology and Flooding Predictor evolved from advisory to closed-loop application The Flooding Predictor integrates with Multivariable Predictive Control (MPC) or can be commissioned as a stand-alone application

4 Techlogy benefits Inexpensive software alternative for diagsing flooding problems and increasing column throughput by 3-7% Estimated ROI for original Amoco project in 2006 dollars; $0,000,000/year for $80,000 investment 00% payback in 3 days Virtually eliminates flooding events and the negative consequences associated with them: Throughput reduction Environmental excursions Equipment damage Risk to personal safety Increase energy efficiency Low installation and maintenance costs

5 Techlogy basis Flooding Predictor recognizes unique patterns of behavior among process variables as the column approaches flood Patterns are based on derivative values (rate of change) of column variables: reboiler temperature, levels, flows, delta temperature, and delta pressure Variables are chosen based on observation and analysis of their derivative values as the column approaches and enters flood When enabled, the Flooding Predictor compares current derivative values against critical derivative limits identified during step-tests When the critical limits are met, the Flooding Predictor warns of imminent flood or in closed-loop form momentarily reduces column operating severity by a predetermined value

6 Pre-flood patterns Comprised of changes in column variables, which occur well within rmal alarm limits. Temporary change in Overhead Flow 40 MSQFD 0 MSQFD 0 Temporary change in Delta Pressure 00 psig 0 psig Temporary change in Bottom Temperature 400 deg 0 0 deg 0 Temporary change in Level or Bottom Flow 00% 0% 0

7 Pre-flood pattern identification Changes are subtle, transient and simultaneous Changes in raw variables are virtually indistinguishable from rmal process ise Pre-flood patterns are well within rmal alarm limits Individual derivatives exceed their critical values frequently Simultaneous behavior present only at pre-flood conditions Pre-flood patterns occur up to 60 minutes in advance of flood event Temporary change in Overhead Flow 40 MSQFD 0 MSQFD 0 Temporary change in Delta Pressure 00 psig 0 psig 400 deg 0 deg 0 Temporary change in Bottom Temperature Temporary change in Level or Bottom Flow 00% 0% 0 0

8 Motiva commercial demonstration Motiva Enterprise Inc., Norco, Louisiana Actual test data of flood prediction on Motiva depropanizer; Norco, Louisiana USA

9 Pre-flood modeling 400 deg 00 psig Temporary increase in Delta Pressure, 0 psig deg 0 deg Change in engineering units/time, i.e., 0.56 degrees F/minute 0 Temporary increase in Bottom Temp. 0 deg 00% Temporary decrease in Level or Flow, 0% 0

10 Original closed-loop applications FCC Vapor recovery Feed Target Feed Rate Effect of flooding events on unit throughput Effect of eliminating flooding and operating column at or near its hydraulic limit

11 Why is this technique beneficial? Shifts control objective from conventional delta-pressure to the true hydraulic limit Hydraulic limit Column dp Capacity Upper dp limit 6%+ capacity increase proven in research at the University of Texas at Austin

12 University of Texas finite reflux test DISTILLATION COLUMN 8" TRAY SPACING Conventional distillation column operated at finite reflux, serviced by a kettle reboiler and horizontal condenser FC203 condenser T2070 accumulator Overhead reflux in top tray temperature control FC200 LT203 T2073 PDT25 feed tank FC204 Steam reboiler in pressure compensated temperature control FC20 LT600 T207 Independent feed flow control reboiler Bottoms level control Column pressure control with N2 Condensate LT204 reflux pump bottoms pump feed pump

13 University of Texas finite reflux test runs COMPOSITION (C6) RUN PREDICTOR FLOOD FEED RATE PRESS DRP REFLUX RATIO (gpm) (in H2O) FEED TOP BOT (%) (%) (%)

14 University of Texas finite reflux test runs COMPOSITION (C6) RUN PREDICTOR FLOOD FEED RATE PRESS DRP REFLUX RATIO (gpm) (in H2O) FEED TOP BOT (%) (%) (%)

15 Conclusions; Separation Research Program, University of Texas at Austin The Flooding Predictor works on a variety of columns. The Flooding Predictor controls the column very close to the flood point, where the highest efficiency and highest capacity occur. The Flooding Predictor can be installed on nearly any process control computer. Thorough testing at the SRP conclusively indicate DCFP can increase throughput and prevent flooding while maintaining efficiency. This equates to a 6.22% improvement in sustainable feed rate.

16 Typical demonstration plan Favorable licensing agreement for commercial-scale demonstration site Identification criteria for demonstration column Establish consensus on measure of success Meet with unit personal Conduct a preliminary assessment of column Determine demonstration test objectives Early analysis point building and derivative data collection Pre-commission phase Commissioning phase Post-commissioning and Performance data collection