1 Visit at Perstorp Daniel Greiner Edvardsen (Master student) Johannes Jäschke (PhD) April 14th, 2010

2 Perstorp 830 km

3 Our Department Department of Chemical Engineering –Petrochemistry and Catalysis –Colloid and Polymer Chemistry –Reactor Technology –Process-Systems Engineering

4 Process Systems Engineering Group 20 people + 6 diploma students Important topics: –Multi-scale process modelling –Operation and control  Plantwide control –Design and synthesis –Simulation, statistics and optimization –Efficient thermodynamic calculations –Systems biology (since 2008)

5 Self-Optimizing Control Work by Professor Sigurd Skogestad Self-optimizing control is said to occur when we can achieve an acceptable loss (in comparison with truly optimal operation) with constant setpoint values for the controlled variables without the need to reoptimize when disturbances occur. Reference: S. Skogestad, “Plantwide control: The search for the self-optimizing control structure'', Journal of Process Control, 10, (2000). Using offline analysis to find good controlled variables

6 Self-Optimizing Control Acceptable loss ) self-optimizing control

7 Our Self-Optimizing variable Please note: Our new control strategy is confidential

8 Our Self-Optimizing variable Properties –Maximizes T end –Relies only on cheap temperature measurement, i.e.: No flow meaurements No technical data necessary (HE area, U-values, Cp etc.) –Best for well designed processes Because of ΔT lm approximation

9 Approximation If 1/1.4 < Θ 1 / Θ 2 < 1.4 the error is less than 1% Source:

10 Our Self-Optimizing Variable - Case I: 2 heat exchangers in series

11 Our Self-Optimizing Variable - Case I: 2 heat exchangers in series

12 Our Self-Optimizing Variable - Case II: 2 heat exchangers in series and 1 in parallel

13 Our Self-Optimizing Variable - Case II: 2 heat exchangers in series and 1 in parallel

14 Our Self-Optimizing Variable - Case I+II: Perstorp HEN

15 Our Self-Optimizing Variable - Case I+II: Perstorp HEN

16 Our Self-Optimizing Variable - Case I+II: Perstorp HEN Setpoint, i.e. c 1s = c 2 and c 3s = c 2

17 Results for 2010 analysis T max - T measured

18 May 26, 12:00 Measured T end ≈ 125.2°C T SOC ≈ 128.3°C

19 June 16, 16:00 Measured T end ≈ 126.6°C T SOC ≈ 127.5°C

20 July 31, 20:00 Measured T end ≈ 127.2°C T SOC ≈ 129.8°C

21 December 26, 11:00 Measured T end ≈ 117.8°C T SOC ≈ 119.9°C

22 Sources of Error Measurement errors Cp-values and densities (assumed constant)

23 Dynamic Simulations In progress Similar to steady-state simulations

24

25 Response with disturbances applied - 10% increase in Th2in

26 Response with disturbances applied - 10% increase in Th2in

27 Response with disturbances applied - 10% increase in Th1in

28 Response with disturbances applied - 10% increase in Th1in

29 Conclusion Simple control structure Close to optimal operation With well-tuned controllers good disturbance rejection can be achieved

30 Thank you!