heat exchanger control systems. some types of heat exchangers sensible heat cooling and heating...
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Heat Exchanger Control Systems
Some Types of Heat Exchangers
• Sensible Heat Cooling and Heating• Change of Phase Boilers and Condensers• Partial Condensing or Partial Vaporization • Wiped Film Units for Viscous Fluids
Basic Model
• Simple Heater Loop
• Actual loop on P&ID
Riggs & Karim, Chemical and Bio-Process Control, 2006, p. 12
Control Loop Options
• Feedback has some lag time
• Feedforward based on steady state process
Perry, Chemical Engineers Handbook, 7th Ed., p. 8-17
Alternate Methods
• Bypass Control Options
• Combined Feedback & FeedForward
Marlin, Process Control Designing Processes and Control Systems for Dynamic Performance, 2000, p.784
Riggs & Karim, Chemical and Bio-Process Control, 2006 p. 401
Physical Installation • Cascade control
http://www.spiraxsarco.com/resources/steam-engineering-tutorials/control-applications/pressure-control-applications.asp
Change of Phase HX
• Condenser on Distillation Column
http://eweb.chemeng.ed.ac.uk/courses/control/restricted/course/fourth/course/module3-1.html
Change of Phase HX
• Partial Condenser on Distillation Column
http://eweb.chemeng.ed.ac.uk/courses/control/restricted/course/fourth/course/module3-1.html
Change of Phase HX
• Reboiler on Distillation Column
http://eweb.chemeng.ed.ac.uk/courses/control/restricted/course/answers/fourth/answer2.html
Condenser Pressure ControlTowler & Sinnott, Chemical Engineering Design Principles, Practice and Economics of Process Design, 2008, p. 279
Steam Boiler Control
• Steam Pressure is used to control fuel feed rates
• Can be linked to consumer
http://www.powermag.com/issues/features/Drum-pressure-the-key-to-managing-boiler-stored-energy_300.html
Actual Boiler Control Systems
• Allow for capacitance in system
http://www.powermag.com/issues/features/Drum-pressure-the-key-to-managing-boiler-stored-energy_300.html
Boiler Drum Level Control
• Can use feedback, feedforward & combination
Riggs & Karim, Chemical and Bio-Process Control, 2006, p. 12
Partial Condenser Options
• Can control reflux rate
William L. Luyben, Alternative Control Structures for Distillation Columns with PartialCondensers, Ind. Eng. Chem. Res. 2004, 43, 6416-6429
Partial Condenser Options
• Can control condenser cooling rate
William L. Luyben, Alternative Control Structures for Distillation Columns with PartialCondensers, Ind. Eng. Chem. Res. 2004, 43, 6416-6429
Partial Condenser Options
• Can control reflux ratio
William L. Luyben, Alternative Control Structures for Distillation Columns with PartialCondensers, Ind. Eng. Chem. Res. 2004, 43, 6416-6429
Wiped Film Evaporator• Control product feed rate
http://www.artisanind.com/ps/docs/rototherm.pdf
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