1

Exercise 3

• From Fujio Kida, JGC Co.

• All cases– Write on where throughput manipulator (TPM) is located– Is the system consistent?

• If “yes”, is it local-consistent?• If “no” propose a fix

• You should use the “consistency rules” (mass balance regulation) to justify your answers

• For difficult problems, Kida recommends to write down the equations and see if there is any solution, for example, using the Maxima software

– See subdirectory Kida-software

Six articles on Plantwide process control in “Chemical Engineering” (Tokyo). 2004 (In Japanese)

2

5. OK?

Note: CV here means ”control valve” (so it is actually the MV).

3

6. OK?

Assumption for pumps: Flow (W1) is not fixed but depends on pressure difference (P2-P1)

4

8. OK?

5

9. OK? Where is production set?

6

10. OK? Where is production set?

7

11. OK? Where is production set?

8

13. OK? (Where is production set?

9

16. OK?

10

17. OK?Cooling of side stream from distillation column (“liquid pumparound”). Liquid is send back again to same place so behaves as closed system.

11

18. OK?

12

19. OK? How would you reconfigure if you want max. production and “Acid Gas” is bottleneck?

13

20. OK?

14

21. EXTRAConsistent?

Note: CV here means ”control valve” (so it is actually the MV).

15

22. OK?

16

23. OK?

17

• (Case-A) P8 by CV9: (as shown in flowsheet) – (A-1) Is it consistent? – (A-2) How can P5 be controlled without becoming inconsistent? (By which CVi?) – (A-3) Is it possible to implement an additional Flow Controller (FC) on W2, W3 or

WR? and which valve (CV) can be employed without becoming inconsistent ? – (A-4) How can P4 be controlled without becoming inconsistent?

• (Case-B) P8 by CV8: (instead of by CV9, see Fig. 24B): Same questions!

24. OK?See next pages for identical problem, but with gas.

Note: CV here means ”control valve” (so it is actually the MV).Assume a fixed pump power (or compressor power)

Justify all your answers. Kida has a price for the best solution

18

24A

Pd

一定

Pu

一定

PC2

P2

P1 P2 P3 P4 P5CV1 CV2 CV3 CV4 CV5 CV6

FC

W1

CV10 CV9 CV8 CV7P9 P7 P6

W1 W2 W3

PC8

P8

Comp

WR

Ｍ

P8

ﾘｻｲｸﾙｶﾞｽｺﾝﾌﾟﾚｯｻｰ

19

24B

Pd

一定

Pu

一定

PC2

P2

P1 P2 P3 P4 P5CV1 CV2 CV3 CV4 CV5 CV6

FC

W1

CV10 CV9 CV8 CV7P9 P7 P6

W1 W2 W3

PC8

P8

Comp

WR

Ｍ

P8

ﾘｻｲｸﾙｶﾞｽｺﾝﾌﾟﾚｯｻｰ