Rr322301-instrumentation--and--process-control

Set No. 1

Code No: RR322301

III B.Tech Supplimentary Examinations, Aug/Sep 2008 INSTRUMENTATION AND PROCESS CONTROL (Bio-Technology) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. In the following figure1, P1 ,P2 and P3 refer to changes in the pressures upstream, in the tank and downstream respectively and the flows into and out of the tank are influenced by the tank pressure.

Figure 1 (a) Write the differential equation for the above system and get the transfer function. (b) What is the order of the above system? How will the order change if there are several inlets and outlets? [10+6] 2. (a) Is the Thermometer Bulb and well arrangement a non-interacting system? Justify your answer. (b) Write the differential equations and determine the transfer function for Thermometer bulb and well arrangement. [6+10] 3. (a) Explain with analytic expression, the concept of a single controller mode which is anticipatory in nature. List its characteristics. (b) Why a pure derivative is not preferred? Draw the derivative controller output for the error given below figure3b. (Assume the relevant settings) [8+8]

Figure 3b 4. (a) Explain in detail, the realization of proportional-integral action with the aid of bellows, flapper-nozzle etc. (b) Draw a three mode electronic controller and derive the expression for the output voltage. [8+8]

1 of 2

Set No. 1

Code No: RR322301

5. (a) Explain the following terms as applicable to system evaluation with necessary graphs. i. Stability ii. measure of quality . (b) Discuss the quarter - amplitude criterion to evaluate the response.

[8+8]

6. (a) Draw the block diagram of the final control operation and explain each block with examples. (b) A magnetic amplifier requires a 5-10 Volt i/p signal from 4-20mA control signal Design a signal conversion system to provide this relationship. (Assume the values of suitable components). (c) What is an actuator and what is its role in the final control operation of a process control system. [6+6+4] 7. (a) Write about requirements of pressure drop across the valve for better control of flow. (b) Write clearly existence of cavitations in control valves?

[8+8]

8. (a) Explain the process of controlling reflux in distillation column. (b) Explain the control of indirect bottom product in a distillation column. [8+8] ⋆⋆⋆⋆⋆

2 of 2

Set No. 2

Code No: RR322301

III B.Tech Supplimentary Examinations, Aug/Sep 2008 INSTRUMENTATION AND PROCESS CONTROL (Bio-Technology) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. (a) What are the different types of process variables? (b) Name all the variables of a liquid heating tank heated by electric current in an electric heater. (c) Define “Degrees of freedom” and bring out its importance in process control. [6+4+6] 2. (a) Is the Thermometer Bulb and well arrangement a non-interacting system? Justify your answer. (b) Write the differential equations and determine the transfer function for Thermometer bulb and well arrangement. [6+10] 3. (a) Discuss relative advantages and disadvantages of the proportional, integral and derivative control actions. (b) Discuss the characteristic effects of a proportional controller on the closed loop response of a process. [8+8] 4. (a) Explain in detail, the realization of proportional-integral action with the aid of bellows, flapper-nozzle etc. (b) Draw a three mode electronic controller and derive the expression for the output voltage. [8+8] 5. (a) Explain the following terms as applicable to system evaluation with necessary graphs. i. Stability ii. measure of quality . (b) Discuss the quarter - amplitude criterion to evaluate the response. 6. Explain the principle of a direct and reverse pneumatic actuator.

[8+8] [16]

7. A heating furnace requires a control valve passing 10gpm preheated light fuel oil (SP.gr. = 0.8) at full load and only 2 gpm at the smallest heating load. The source pressure constant at 50psi gage, but there is 10psi drop in the oil pre heater and 20 psi drop at the furnace burner nozzles. Remaining pressure drop occurs only at control valve when it is fully opened. (a) Find out control valve size required for the above application. (b) Find out required rangeability of the valve 1 of 2

Set No. 2

Code No: RR322301 (c) Find out characteristic coefficient (α).

[6+4+6]

8. Explain the dead-time compensation in a closed loop operation with neat diagram. [16] ⋆⋆⋆⋆⋆

2 of 2

Set No. 3

Code No: RR322301

III B.Tech Supplimentary Examinations, Aug/Sep 2008 INSTRUMENTATION AND PROCESS CONTROL (Bio-Technology) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. (a) Differentiate between a controlled variable and a manipulated variable. (b) Explain one process control loop with neat diagram. (c) List all the variables involved in this loop. (d) Name the controlled variable and the manipulated variable in this loop.[3+7+3] 2. (a) Say whether heated tank and an immersed thermometer with negligible interaction is interacting or non-interacting. Justify your answer. (b) Write the differential equations and determine the transfer functions individually for heated tank and thermometer. (c) Determine the overall transfer function of this combination. How is this transfer function related with the individual transfer function? [3+9+4] 3. (a) Explain the principle of different types of discontinuous controller modes with examples. Mention them applications. (b) Distinguish between multi position controller mode and floating control mode with neat sketches. [10+6] 4. (a) Explain in detail, the realization of proportional-integral action with the aid of bellows, flapper-nozzle etc. (b) Draw a three mode electronic controller and derive the expression for the output voltage. [8+8] 5. (a) Explain the following terms as applicable to system evaluation with necessary graphs. i. Stability ii. measure of quality . (b) Discuss the quarter - amplitude criterion to evaluate the response.

[8+8]

6. (a) What is the principle of a solenoid and explain how it can be used to change the gears of a two-position transmission. (Let an SCR is used to activate the solenoid coil). (b) A stepping motor has 130 steps per revolution. Find the digital input rate that producer 10.5 revolutions per second. [10+6]

1 of 2

Set No. 3

Code No: RR322301

7. A heating furnace requires a control valve passing 10gpm preheated light fuel oil (SP.gr. = 0.8) at full load and only 2 gpm at the smallest heating load. The source pressure constant at 50psi gage, but there is 10psi drop in the oil pre heater and 20 psi drop at the furnace burner nozzles. Remaining pressure drop occurs only at control valve when it is fully opened. (a) Find out control valve size required for the above application. (b) Find out required rangeability of the valve (c) Find out characteristic coefficient (α).

[6+4+6]

8. What is a ratio control system? Why it is useful for the process control? Give any three examples? [16] ⋆⋆⋆⋆⋆

2 of 2

Set No. 4

Code No: RR322301

III B.Tech Supplimentary Examinations, Aug/Sep 2008 INSTRUMENTATION AND PROCESS CONTROL (Bio-Technology) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. (a) An open loop cylindrical tank 1.2 metre in diameter is filled with water to a depth of 0.9 metre. The water flows out through a 2-inch control valve at an average rate of 0 .136 cubic metre/min. If the input is increased from 0.136 to 0.182 cubic metre/min, what is the new depth in the tank and about how long will it take to accomplish 95% of the change in level? (b) Calculate the transfer function relating tank level to valve position, and compare with the transfer function relating level and input flow. [7+9] 2. (a) Differentiate between a non-interacting system and an interacting system. (b) Give one example each for non-interacting system and interacting system. (c) Derive the transfer functions for the above two systems and discuss how they differ. [3+2+11] 3. (a) Describe the output of a three mode controller for an assumed error variation. Discuss its features. (b) Specification of a PI controller are Kp =7, Ki = 2 sec−1 and PI (0) (controller output at t=0)=24%. Plot the controller output as the function of time for the given error as shown in figure3b. [8+8]

Figure 3b 4. (a) Explain in detail, the realization of proportional-integral action with the aid of bellows, flapper-nozzle etc. (b) Draw a three mode electronic controller and derive the expression for the output voltage. [8+8] 5. (a) A proportional - integral controller is used on a pure time - delay process. Calculate the response to a step change in load if the controller gain is half the maximum value and the reset time is half the time delay. Calculate the integral of the absolute error.

1 of 2

Set No. 4

Code No: RR322301

(b) Suggest and explain the control schemes for better control of process with dead time. [8+8] 6. (a) Give the principle of the control valve and give its O/P equation. (b) A pressure difference of 1.5 psi occurs across a constriction in a 4 cm diameter pipe. The constriction constant is 0.008 w3 /s/(kPa)1/2 . Find i. the flow rate in m3 /sec. ii. flow velocity in m/sec.

[8+8]

7. (a) Give the schematic of single seated and double seated valves. (b) What are the advantages and disadvantages of single seated and double seated valves. [8+8] 8. Design a feed forward controller for a stirred heater with respect to steady state error & dynamic forward controller and give the conclusions of the design. [16] ⋆⋆⋆⋆⋆

2 of 2