i) the measurement, and (f mark)
ii) the controlled variable. [1 mark]
c) Draw a schematic for feedbackfieedforward combination for tilis procest. [6 marks]
The figure below shows a boller drum used to generate steam that is to be used in downstream
Question 2 processes. The steam demand for downstream processing units can be made at any time and the boller has to meat such demands. The liquid level in the boiler is, as a consequence, affected by the demand.
a) For this process, identify the following:
i) The controlled variable, [1 mark]
ii) the disturbance variable(s), and [2 mark]
iii) the manipulated variable(s). [1 mark]
b) Come up with (sketch) the following control strategies to ensure the identfied controlled variable is maintained near its set point:
i) Feedback control, and [5 marks]
ii) feedfonward control. [5 marks\}
c) Can the two control configurations be combined? Why? [2 marks]
d) Is cascade control possible for this process? Explain. [3 marks]
e) Propose (sketch) a cascade control strategy for the boiler process. [6 marks]
End of testll!
