TWOTANK - Two Tank Level Control

Liquid flows through a system of two tanks arranged in series, as shown below. The level control of tank 2 is based on the regulation of the inlet flow to the tank 1. This tank represents a considerable lag in the system. The aim of the controller is to maintain a constant level in tank 2, despite disturbances which occur in the flow F3. 

Mass balance equations with constant density yields for tank 1 

Constant A2=3 Constant Kl=0.5 Constant K2=1.2 Constant F0in=l Constant F30=l Constant F3AMP=0 Constant H10=0 Constant H20=0 Constant H2set=2 Constant Kc=4 Constant CINT=2, 

Area tank 1 Area tank 2 Outflow constant Outflow constant Initial flow to Average flow of 

Amplitude of disturbance Initial level tank 1 Initial level tank 2 Set-point level for tank 2 Controller constant TFIN=80 RESET GOTOl 

5 Simulation Tools and Examples of Chemical Engineering Processes 

Note the change in the value of the proportional gain KP is changed at 90 h by use of an IF-THEN-ELSE statement  

With no control Kp = 0 and constant flow of F3, study the response of the levels hi and h2 and final steady-state values for differing flow rates Fq and F3. 

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