Chapter 1 SQ

Apply Your Knowledge

1.6
For each common household item, decide whether it uses automatic feedback to achieve its performance goals.

Feedback


i	The microwave is wonderful for making popcorn or reheating food.	answer
ii	The hot water heater is a convenience that provides hot water without waiting.	answer
iii	The toilet tank stores water, which can be used to flush the toilet bowl; we are glad the toilet tank stores the correct amount of water.	answer

1.7
A process is depicted in textbook Figure 1.8 and repeated below. You may not change the process, and the valves are the only variables that can be manipulated. Can the following variable be controlled by feedback?

Feedback


i	L2 Flash Drum Liquid Level
ii	T5 Reactor Temperature
iii	P1 Flash Drum Pressure

1.8
From the figure, check all of the statements which can be ascertained to be TRUE.

Control Schematic

	The reactor is perfectly mixed
	When valve 2 (v2) is closed, T3 approximately = T1
	By closing valves, all flows to and from the flash drum can be stopped
	The hot oil temperature T8 > reactor effluent T6
	Liquid from the flash separator flows by gravity to return to the reactor

1.9
You are designing controls for the CSTR in the figure. What are some of the disturbances that the control system should compensate?

Control Schematic

	Feed composition
	Lack of perfect mixing
	Errors in the level sensor
	Feed temperature
	Poor understanding of reaction engineering by the engineers