{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

ch23.pdf - 123456789 8 23.1 Option(a Production rate set...

Info icon This preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
23-1 ±²³´µ¶·¸¹º¸ 23.1 Option (a): Production rate set via setpoint of w A flow controller Level of R 1 controlled by manipulating w C Ratio of w B to w A controlled by manipulating w B Level of R 2 controlled by manipulating w E Ratio of w D to w C controlled by adjusting w D Options (b)-(e) are developed similarly. See table below. Option Production Rate Set With Control Loop # Type of Controller Controlled Variable Manipulated Variable a w A 1 Flow w A,m w A (V1) w A 2 Ratio w B,m w B (V2) w A 3 Level H R 1 w C (V3) w A 4 Ratio w D,m w D (V4) w A 5 Level H R 2 w E (V5) b w B 1 Flow w B,m w B (V2) w B 2 Ratio w A,m w A (V1) w B 3 Level H R 1 w C (V3) w B 4 Ratio w D,m w D (V4) w B 5 Level H R 2 w E (V5) c w C 1 Flow w C,m w C (V3) w C 2 Ratio w B,m w B (V2) w C 3 Level H R 1 w A (V1) w C 4 Ratio w D,m w D (V4) w C 5 Level H R 2 w E (V5) d w D 1 Flow w D,m w D (V4) w D 2 Ratio w C,m w C (V3) w D 3 Level H R 1 w A (V1) w D 4 Ratio w B,m w B (V2) w D 5 Level H R 2 w E (V5) e w E 1 Flow w E,m w E (V5) w E 2 Ratio w D,m w D (V4) w E 3 Level H R 2 w C (V3) w E 4 Ratio w B,m w B (V2) w E 5 Level H R 1 w A (V1) Subscript m denotes “measurement”. Solution Manual for Process Dynamics and Control, 2 nd edition, Copyright © 2004 by Dale E. Seborg, Thomas F. Edgar and Duncan A. Mellichamp
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
23-2 In options c, d, and e, valves 1 and 2 can be used interchangeably. Thus, a total of 8 options can be developed. Advantages and Disadvantages: Each option is equivalent in the sense that 5 control loops are required: 1 flow, 2 level, and 2 ratio. Since there is no cost or complexity advantage with any option, the production rate should be set via the actual product rate, w E , i.e. option e. V1 V2 V3 P1 V4 P2 V5 2 W B 1 W C W D W E R1 R2 1 2 3 4 LT LT FT FT FT FT 5 FT 1 2 FC RC 3 LC 5 LC 4 RC
Image of page 2
23-3 23.2 a) The level in the distillate ( H D ) will be controlled by manipulating the recycle flow rate ( D ), and the level in the reboiler ( H B ) via the bottoms flow rate ( B ). Thus, H D and H B are pure integrator elements. Closed-loop TF development assuming PI controller: 2 1 ( ) ( ) 1 I CL I I c p s G s s s K K τ + = τ τ + Relations: 2 I c p K K τ = τ 2 I τ = ζτ 1 p K = - for both H D and H B loops. ±²³´µ = 1 for a critically damped response Initial settings: 0.4 10 c I K = - τ = Final tuning: changed to proportional control only to obtain a faster response 1 c K = - b) The distillate composition ( x D ) will be controlled by manipulating the reflux flow rate ( R ), and the bottoms composition ( x B ) via the vapor boilup ( V ). Use a step response to determine an approximate first-order model (calculations are shown on last page). 0.0012 2.33 1 0.000372 2.08 1 D B x R s x V s = + - =
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
23-4 Using the Direct Synthesis method: ( ) 1 1 ( ) (1 ) c c K G s s G s K s = τ + τ = + τ τ Choosing 1 4 c τ = τ , the settings are: x D - R loop { 3333.3 2.33 c I K = τ = x B - V loop { 10649.6 2.08 c I K = - τ = c) The reactor level ( H R ) will be controlled by manipulating the flow from the reactor ( F ).
Image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern