A mixing process consists of a single tank that is instrumented, as shown in the figure below. The temperature of stream A varies with time, and the controller attempts to compensate for this by varying the mass flow rate of stream A. The full data of the control system is given below.

For a step change in input pressure, the valve shows first-order behavior, and it requires one minute to settle within 5%.

 • Draw a detailed block diagram for the controlled process. Include

 ➢ the name and units for each of the signals in the block diagram, and 

➢ a block for each of the parts of the controlled process. 

 • Derive a transfer function for each block in your block diagram. 

Transcribed Image Text:

Process Transfer line The volume of the tank is constant V = 5m3 (i) The transfer line is 20m long and has 0.5m (i) (ii) The feed mass flow rate of stream B is inside diameter kg constant WR = 700 min (i) The volume of the pump can be neglected Temperature transmitter data T(°C) (ii) The mass flow rate of stream A changes but it kg Tm(mA) is smaller than WR. WA = 50, min 45 (iv) The temperatures of both streams are TA = 100 °C and TR = 50 °C 120 20 The density of the liquid in the tank is kg (v) Transmitter dynamics are negligible constant p = 9509 m2 IP Transducer Data PID Controller P(mA) Pr(psi) A derivative on measurement only dTm et)dt ) + Ka (i) 4 p(t) = p + Kc ( e(t) +- dt 20 15 (ii) (ii) Direct or reverse acting as required Current (mA) input and output signals Control Valve An equal percentage valve is used, which has the following relation: Pp-3 q = 0.02 + 0.04(25) 12 Process Transfer line The volume of the tank is constant V = 5m3 (i) The transfer line is 20m long and has 0.5m (i) (ii) The feed mass flow rate of stream B is inside diameter kg constant WR = 700 min (i) The volume of the pump can be neglected Temperature transmitter data T(°C) (ii) The mass flow rate of stream A changes but it kg Tm(mA) is smaller than WR. WA = 50, min 45 (iv) The temperatures of both streams are TA = 100 °C and TR = 50 °C 120 20 The density of the liquid in the tank is kg (v) Transmitter dynamics are negligible constant p = 9509 m2 IP Transducer Data PID Controller P(mA) Pr(psi) A derivative on measurement only dTm et)dt ) + Ka (i) 4 p(t) = p + Kc ( e(t) +- dt 20 15 (ii) (ii) Direct or reverse acting as required Current (mA) input and output signals Control Valve An equal percentage valve is used, which has the following relation: Pp-3 q = 0.02 + 0.04(25) 12 Process Transfer line The volume of the tank is constant V = 5m3 (i) The transfer line is 20m long and has 0.5m (i) (ii) The feed mass flow rate of stream B is inside diameter kg constant WR = 700 min (i) The volume of the pump can be neglected Temperature transmitter data T(°C) (ii) The mass flow rate of stream A changes but it kg Tm(mA) is smaller than WR. WA = 50, min 45 (iv) The temperatures of both streams are TA = 100 °C and TR = 50 °C 120 20 The density of the liquid in the tank is kg (v) Transmitter dynamics are negligible constant p = 9509 m2 IP Transducer Data PID Controller P(mA) Pr(psi) A derivative on measurement only dTm et)dt ) + Ka (i) 4 p(t) = p + Kc ( e(t) +- dt 20 15 (ii) (ii) Direct or reverse acting as required Current (mA) input and output signals Control Valve An equal percentage valve is used, which has the following relation: Pp-3 q = 0.02 + 0.04(25) 12 Process Transfer line The volume of the tank is constant V = 5m3 (i) The transfer line is 20m long and has 0.5m (i) (ii) The feed mass flow rate of stream B is inside diameter kg constant WR = 700 min (i) The volume of the pump can be neglected Temperature transmitter data T(°C) (ii) The mass flow rate of stream A changes but it kg Tm(mA) is smaller than WR. WA = 50, min 45 (iv) The temperatures of both streams are TA = 100 °C and TR = 50 °C 120 20 The density of the liquid in the tank is kg (v) Transmitter dynamics are negligible constant p = 9509 m2 IP Transducer Data PID Controller P(mA) Pr(psi) A derivative on measurement only dTm et)dt ) + Ka (i) 4 p(t) = p + Kc ( e(t) +- dt 20 15 (ii) (ii) Direct or reverse acting as required Current (mA) input and output signals Control Valve An equal percentage valve is used, which has the following relation: Pp-3 q = 0.02 + 0.04(25) 12