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143.461 Modern Multivariable Control
You are required to control a continuous, stirred tank reactor (CSTR). This consists of a tank into which water flows at the rate of 2 litres per second. There is an outlet valve which you must control and set between 0 and 100% open. The tank has a wall steam jacket, whose temperature you can control - within limits.
The inlet stream usually has a constant effluent concentration of 10 moles per cubic metre. The fluid suffers a temperature-dependant reaction and consumes some of the inlet species .
It is your job to control steam temperature and output flow in such a way as to get as low an exit concentration as possible. You must avoid overfilling the tank and allowing the tank temperature to reach boiling point (100 C). You will do this in VB6 and present a running graph of the controlled and state variables.
There is a wash-down every two hours and the inlet flow doubles for 20 minutes during this time, the concentration of the species in the inlet stream halves to 5 moles per cubic meter.
Data and Nomenclature:
Valve = variable [%]
D = tank diameter = 2m
H = liquid height – variable – max 2.5 m after which a catastrophe happens and you get to mop it up
Tout = outlet temperature [degrees]
Cout = outlet concentration [moles/m3]
Tsteam = steam temperature [degrees] ( max = 300, min = 50)
Tin = inlet temperature (fixed) = 25 degrees
KWall = 600 W/degree/m^2/second
Rho = fluid density = 1000 kg/m^3
Cp = specific heat = 4.18 [J/cc/degree]
Hr = heat of reaction = 45 [kJ/mole]
Rk = rate constant = 578 000 [m3/mol/s]
AE = Activation energy = 5000 [degrees]
RR = Reaction Tate [mol/m3/s]
OF = outlet Flow [m3/s]
Reaction Rate Equation;
RR = Rk*exp(-AE/(Tout + 273.16)) * Cout^2
OF = Valve*0.000006*SQR(Rho*g*H) [m3/s]
You should assume the following initial conditions:
H= 10 cm
Ctank= 10 moles/m^3
The work-product from this project is a VB Project, with pretty GUI, which will run and please the examiner. Your GUI must show operation for 1.5 shifts = 12 hours.
i need this asap within a few hrs
hopefully this would help
As you work towards an optimal control strategy for the CSTR project you should be aware of the following:
1. The given starting conditions (H, T and C) drive dnelm into mad computations (eg. negative concentration) – so you should play around with these values until you find that you get reasonable H, T and C in the first few steps of calfun.
2. I mentioned that you would need rails on H and T, but there are also other rails that will lead to a better engineering solution. For example, several of you have reached a solution where the control valve position varies rapidly from second to second. In real life, you would not tolerate a valve that opened and closed rapidly, because the valve would fail quickly. Ideally, you want the valve adjustment from one second to the next to change by a maximum of about 10% of its previous position. The gentler the change in the valve position, the longer its life.