The level of liquid in a reboiler on a distillation column is controlled by using feedback control to throttle a valve on the liquid product (see below P&ID). However, the pressure of vapour above the liquid in the reboiler also affects the flow rate of liquid product, as an increase in pressure above the liquid will push the liquid through the product line faster. a) Draw a cascade arrangement where the vapour pressure is measured as the secondary variable. b) Draw a cascade arrangement where the actual flowrate in the liquid product stream is measured as the secondary variable.

The level of liquid in a reboiler on a distillation column is controlled by using feedback control to throttle a valve on the liquid product (see below P&ID). However, the pressure of vapour above the liquid in the reboiler also affects the flow rate of liquid product, as an increase in pressure above the liquid will push the liquid through the product line faster. a) Draw a cascade arrangement where the vapour pressure is measured as the secondary variable. b) Draw a cascade arrangement where the actual flowrate in the liquid product stream is measured as the secondary variable.

Understanding Motor Controls

4th Edition

ISBN:9781337798686

Author:Stephen L. Herman

Publisher:Stephen L. Herman

Chapter54: The Operational Amplifier

Section: Chapter Questions

Problem 7RQ: Name two effects of negative feedback.

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