INSTRUMENTATION & PROCESS CONTROL Question Papers (Regular,2007)

SET : 1

1. Write the differential equations of the following liquid level process as shown in figure

(click on the image to have a clear view)

Derive the transfer function H(S)/M(S) of this liquid level process.

What is the order of this system?

2. Give an example for interacting first order elements in series.

Write the differential equation for this combination and determine the transfer function.

Comment on the transfer function.

3. Explain with a neat sketch depecting the error vs controller output, the principle of a proportional controller action.

With an example explain how offset error in proportional controller occurs. Suggest a way to overcome offset error.

4. Briefly explain the principle of operation of a “displacement type” pneumatic P.D controller. How the “derivative time” can be adjusted in this controller.

Outline the design steps involved in developing an electronic PI controller.

5. What is meant by process tuning and list the various methods of tuning of PID parameters.

Discuss process reaction method for control loop tuning.

6. Explain the essential features of a control valve.

Explain the different responses of the 3 main types of control valves with respect to stem position and give reasoning.

7. A heating furnace requires a control valve passing 10gpm preheated light fuel oil (sp.gr = 0.8) at full load and only 2gpm at the smallest heating load. The source pressure constant at 50psig, but there is 10psig drop in the oil preheater and 20psig 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 character coefficient.

8. Draw the feed forward and feed back control systems that regulate the flow through the pipe? Discuss about both the control systems and give reasons to select any of the two systems in maintaining the desired flow.

SET : 2

1. Write differential equation for the following single capacitance process as shown in figure.

The above single capacitance level process has a normal operating head of 1.2 meter and a normal value of outflow of 3375 cubiccentimeter per seconds. The cross section area of the vessel is 0.54 sqmt. If the resistance to the flow is parabolic, determine the time constant of the system.

Show that the time constant of the above process is proportional to the time required to change the fluid in the vessel.

2. Say whether heated tank and an immersed thermometer with negligible interaction is interacting or non – interacting. Justify your answer.

Write the differential equations and determine the transfer functions individually for heated tank and thermometer.

Determine the overall transfer function of this combination. How is this transfer function related with the individual transfer function.

3. Explain with analytical expression, the concept of a single controller mode which is anticipatory in nature.

Why a pure derivative is not preffered? Draw the derivative controller output for the error given below figure (assume the relevant settings)

4. What are the advantages of the force type pneumatic controllers. Describe with neat diagrams, the working of a force type pneumatic proportional controller.

Explain the working principle of a hydraulic proportional controller. How proportional gain can be adjusted in this controller.

5. Repeated
6. Give the principle of the control valve and give its o/p equation.

A pressure difference of 1.5 psi occur across a constriction in a 4cm diameter pipe. The constriction constant is 0.008wm/s(kpa)1/2. Find 1) the flowrate in m3/sec 2) flow velocity in m/s.

7. Repeat
8. Write short notes on

a) Material balance in a distillation column.

b) Quality control (top & bottom) distillation column.

c) Quantity control (top & distillation) distillation column.

SET : 3

1. Write the different equations for the following liquid level process & hence derive the transfer function of the system as shown in figure

Say whether the above system is interacting or non – interacting. Justify your answer.

What are the effective time constants for this liquid level process?

2. Repeat
3. Repeat
4. Explain in detail, the realization of proportional – integral action with aid of bellows, flapper – nozzle etc.

Draw a 3 mode electronic controller and derive the expression for the output voltage.

5. Explain the following terms as applicable to system evaluation with necessary graphs

a) Stability

b) Measure of quality

Discuss the quarter – amplitude criterion to evaluate the response.

6. Explain the principle of hydraulic actuator.

Explain a hydraulic servo system.

7. Write short notes on :

a) Globe valves

b) Ball valves

c) Louvers

8. Explain the nature of multivariable system.

Explain notation & interaction used in multivariable system.

SET : 4

1 – 7 REPEAT

8.Explain the closed loop characterization of cascade control systems.

Explain the primary and secondary loop gain adjustment in a cascade control system.

INSTRUMENTATION & PROCESS CONTROL Question Papers (Regular, 2006)

SET : 1

1. Name five flow laws relating to fluids, heat & electricity and state these laws.
2. Repeated
3. Repeated
4. Repeated
5. Repeated
6. Explain the baffle – nozzle system with the help of its characteristic curves.

Explain the pneumatic booster & what is its need.

Differentiate between direct & reverse action final control operation

7. The area of opening a valve versus left is given by A = a + bx2. Derive the flow versus left characteristic for this parabolic valve.

Liquid glycerine (density 78lb/ft3) is required at maximum flow of 18gpm. The line drop is 40psi and the valve. Pressure drop is 10psi. what size plug valve is required.

8. How do you select the desired value of ratio in the ratio control system.

Explain the ratio control system with respect to :

a) Distillation column

b) Exit vapour stream.

SET : 2

1. A process of unknown transfer function is subjected to a unit impulse input. The output of the process is measured accurately and is found to be represented by the function y(t) = t.e-t. determine the step response of this process.
2. Repeat
3. Discuss the effects of an integral controller on the closed loop response of first order process.

With neat sketches, explain the principle of derivative control action. Summarize its characteristics.

4. Repeat
5. 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.

Suggest & explain the control schemes for better control of process with dead time.

6. Repeat
7. Distinguish different types of butterfly valves.

Mention which are the rotating shaft valves.

8. Explain the principles of cascade control tuning.

State the fundamental difference between feed forward and conventional feedback control.

SET : 3

1. A pressure vessel connected as shown in below figure has a supply pressure u1 of 45 psig, a vessel pressure of 15 psig and an air to atmosphere. The average flow rate is 1 pounds per minute & the vessel volume is 0.3 cubic meter.

Calculate the time constant.

Derive and calculate the system function.

2. Differentiate between a servo problem and regulator operation

Give a typical example for servo operation and explain.

Explain regulator operation and explain.

3. With an example explain how offset error can be eliminated with an integral controller.

With an illustration explain the response of an integral controller to a constant error. Show the effect of integral time on the response.

4. Explain with a neat sketch, the working principle of a displacement type pneumatic proportional controller. Discuss the effect of adding the negative feed back.

With necessary diagrams describe a hydraulic integral controller. Explain how integral time can be adjusted.

5. Repeat
6. A feed hopper requires 30 lb of force to open. Find the pneumatic actuator area to provide this force from a 9 psi input signal.

A hydraulic system uses positions of diameter 2cm & 30cm. what pneumatic pressure is required an the small piston to produce the necessary force.

7. Repeat
8. What control strategy is needed for improved performance when input of a process affected by significant disturbance.

What is compensation in a closed operation. Explain with neat diagram.

SET : 4

1. Derive the process differential equations and the transfer function for the following two capacity level process as shown in figure.

This level system is an interacting system. Say true or false. Support your answer.

Define the system time constants of the above process.

2. Differentiate between a non interacting system and an interacting system.

Give an example each of non-interacting system & interacting system.

Derive transfer functions for the above 2 systems and discuss how they differ.

3. Repeat.
4. With a neat sketch explain the realization of electronic single speed floating controller. How realization rate can be adjusted in such a controller?

State the kind of control action realized in the following circuit figure 3. Also determine the input output relationship.

5. Repeat
6. Give the principle of the control valve and give its output equation.

A pressure difference of 1.5 Psi across a construction in a 4cm diameter pipe. The construction constant is 6.008 w³/s/(Kpa)^1/2.

Find 1) flow rate in m³/sec 2) flow velocity in m/sec

7. Repeat
8. Explain the principles of ratio control with the suitable examples.

INSTRUMENTATION & PROCESS CONTROL Question Papers (Supple, 2006)

SET :1

1. (a) Define time constant of a system. Write the expression for the time constant in terms of the process parameters of a liquid level system.
(b) A tank operating at 3 metre head and 0.022 cubic metre/min outflow through a valve has a cross section area 0.9 square metre. Calculate the time constant.
(c) If this system known to have time constant response requires 5 minutes to indicate 98% of the response, what can be the time constant? [4+6+6]

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 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 figure1. (Assume the relevant settings) [8+8]
Figure 1:

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) What is meant by process tuning and list the various methods of tuning of PID parameters.
(b) Discuss process reaction method for control loop tuning. [8+8]

6. (a) Explain the baffle - Nozzle system with the help of its characteristic curves.
(b) Explain the pneumatic booster and what is its need.
(c) Differentiate between direct and reverse action final control operation.[6+6+4]

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. (a) Explain the objectives of controlling distillation column operation with a neat diagram.
(b) Describe the objective of controlling boiler operation with a neat diagram. [8+8]

SET :2

1. A Cylindrical tank with an area of 20 ft2 and a height of 10 ft has a normal liquid depth of 6ft. The flow to the tank is 10±1 cubic ft/min, and the liquid is discharged through a control valve to a process at atmospheric pressure. ( 1 ft = 0.305 metre) Calculate the time constant if the tank is
(a) Open to the atmosphere
(b) Closed, with a constant pressure of 10 psig above the liquid.
(c) Closed, with a fixed amount of air sealed above the liquid. The initial pressure is 10 psig. [16]

2. Three identical tanks are operated in series in non-interacting fashion. For each tank, R=1 and t = 1. If the deviation in flow rate to the first tank is an impulse function of magnitude 2, determine
(a) An expression for H(S) where H is the deviation in level in the third tank.
(b) Obtain the expression for H(t).
(c) Sketch the response H(t). [7+6+3]

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 figure1. (Assume the relevant settings) [8+8]
Figure 1:

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) Explain the baffle - Nozzle system with the help of its characteristic curves.
(b) Explain the pneumatic booster and what is its need.
(c) Differentiate between direct and reverse action final control operation.[6+6+4]

7. Write steps followed in choosing a valve for better control of flow and should be cost effective. [16]

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]

SET :3

1. A thermometer having first order dynamics with a time constant of 1 min is placed in a temperature bath at 800C. After the thermometer reaches a steady state, it is suddenly placed in a bath at 900C at t = 0 and left there for 1 min, after which it is immediately returned to the bath at 800C.
(a) Derive and write the expression for the response of the thermometer.
(b) Draw a sketch showing the variation of thermometer reading with time.
(c) Calculate the thermometer reading at t = 0.5 min and at t = 2.0 min. [16]

2. (a) Give one example for Interacting first order elements in series.
(b) Write the differential equation for this combination and determine the transfer function.
(c) Comment on the transfer function. [3+10+3]

3. (a) what is meant by differential gap and how it is related to the performance of the final control element?
(b) Define proportional band. Explain the relation between proportional gain, proportional band and offset error.
(c) With a neat sketch explain the integral controller mode action. Summarize the characteristics. [5+5+6]

4. (a) With a neat circuit diagram, explain the realization of an electronic two position controller with adjustable neutral zone.
(b) Design an electronic proportional controllers for (0-12v) error input, 10% proportional band and 50% zero error controller output. [8+8]

5. (a) What is meant by process tuning and list the various methods of tuning of PID parameters.
(b) Discuss process reaction method for control loop tuning. [8+8]

6. (a) Explain the baffle - Nozzle system with the help of its characteristic curves.
(b) Explain the pneumatic booster and what is its need.
(c) Differentiate between direct and reverse action final control operation.[6+6+4]

7. Write about the rotating shaft valves? [16]

8. (a) Explain the closed loop characterization of cascade control system.
(b) Explain the primary and secondary loop gain adjustment in a cascade control
system. [8+8]

SET :4

1. (a) Write differential equation for the following single capacitance process as shown in the figure1
Figure 1:
(b) The above single capacitance level process has a normal operating head of 1.2 metre and a normal value of outflow of 3375 cubic centimetre per seconds. The cross section area of the vessel is 0.54 square metre. If the resistance to the flow is parabolic, determine the time constant of the system.
(c) Show that the time constant of the above process is proportional to the time required to change the fluid in the vessel. [3+7+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 figure2. (Assume the relevant settings) [8+8]

4. (a) Explain the method of realizing an electronic PI controller employing delayed positive feedback. Derive the expression for proportional gain and integral time.
(b) Explain with a neat sketch, the working principle of a moving vane type two position controller. [8+8]

5. (a) Explain the following terms as applicable to system evaluation with necessary graphs.


Figure 2:
i. Stability
ii. measure of quality .
(b) Discuss the quarter - amplitude criterion to evaluate the response. [8+8]

6. (a) Explain the baffle - Nozzle system with the help of its characteristic curves.
(b) Explain the pneumatic booster and what is its need.
(c) Differentiate between direct and reverse action final control operation.[6+6+4]

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. Discuss the cascade control with neat block diagrams
(a) Heat exchangers
(b) Distillation columns
(c) Furnaces. [6+6+4]

INSTRUMENTATION & PROCESS CONTROL Question Papers (Supple, 2005)

SET :1

1. (a) Show that the mercury thermometer which is suddenly immersed in hot waterwith some temperature will follow first order dynamics.
(b) A thermometer having time constant of 1 min is initially at 50C. It is immersedin a bath maintained at 1000 C at t =0;i. Determine the temperature reading at t = 1.2 min.ii. If at t = 1.5 min, the thermometer is removed from the bath and put ina bath at 750C, determine the maximum temperature indicated by thethermometer.iii. What will be the indicated temperature at t = 20 min? [6+10]

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 forThermometer 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 outputfor the error given below figure1. (Assume the relevant settings) [8+8]Figure 1:

4. (a) Explain the method of realizing an electronic PI controller employing delayedpositive feedback. Derive the expression for proportional gain and integraltime.
(b) Explain with a neat sketch, the working principle of a moving vane type twoposition controller. [8+8]

5. (a) Explain the following terms as applicable to system evaluation with necessarygraphs.
i. Stability
ii. measure of quality .
(b) Discuss the quarter - amplitude criterion to evaluate the response. [8+8]

6. (a) Explain the baffle - Nozzle system with the help of its characteristic curves.
(b) Explain the pneumatic booster and what is its need.
(c) Differentiate between direct and reverse action final control operation.[6+6+4]

7. (a) Distinguish different types of butterfly valves.
(b) Mention which are the rotating shaft valves. [12+4]

8. Explain feed forward control for the following
(a) Heat exchangers
(b) Drum boiler
(c) Distillation column. [5+5+6]

SET :2

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 areinfluenced by the tank pressure.Figure 1:
(a) Write the differential equation for the above system and get the transfer func-tion.
(b) What is the order of the above system? How will the order change if there areseveral inlets and outlets? [10+6]

2. Three identical tanks are operated in series in non-interacting fashion. For eachtank, R=1 and t = 1. If the deviation in flow rate to the first tank is an impulsefunction of magnitude 2, determine
(a) An expression for H(S) where H is the deviation in level in the third tank.
(b) Obtain the expression for H(t).
(c) Sketch the response H(t). [7+6+3]

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) (controlleroutput at t=0)=24%. Plot the controller output as the function of time forthe given error as shown in figure2. [8+8]

4. (a) With a neat circuit diagram, explain the realization of an electronic two posi-tion controller with adjustable neutral zone.
(b) Design an electronic proportional controllers for (0-12v) error input, 10%proportional band and 50% zero error controller output. [8+8]Figure 2:

5. (a) Plot the transient response of a process with time constants of 50sec and20sec and a time delay of 10sec. Use the reaction curve method to obtain therecommended settings for a three - mode controller.
(b) What is the phase margin for the recommended controller gain? [10+6]

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

7. Write short notes on.
(a) Sliding stem Valves
(b) Rotating shaft Valves. [8+8]

8. (a) Explain clearly the split range control of the pressure in the steam header?
(b) Determine the properties of the inner loop in a cascade control system andwrite the principle advantages of cascade control system? [8+8]

SET :3

1. (a) A flow head equation has the equation q = hn. Calculate the resistance.
(b) A liquid storage device is spherical in shape. Calculate the capacitance as afunction of head.
(c) If the outflow at a vessel is proportional to the square root of head, what shapevessel results ini. a steady change in headii. a rate of change of head proportional to head? [4+4+8]

2. (a) Define self regulation ?
(b) Explain how self and non self regulated systems operate for step input withexamples. [5+11]

3. (a) Explain with neat sketches, the characteristics of two position and three position controller modes.
(b) What is cycling? Suggest a suitable modification to overcome cycling.[6+10]

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

5. (a) Explain the following terms as applicable to system evaluation with necessarygraphs.i. Stabilityii. measure of quality .
(b) Discuss the quarter - amplitude criterion to evaluate the response. [8+8]

6. (a) Explain the baffle - Nozzle system with the help of its characteristic curves.
(b) Explain the pneumatic booster and what is its need.
(c) Differentiate between direct and reverse action final control operation.[6+6+4]

7. (a) Briefly explain valve sizing
(b) A fully open valve passes 200gpm of water at a pressure differential of 10.0psicalculate valve sizing. [8+8]

8. Explain the economic considerations of feed forward controller? [16]

SET :4

1. In the following liquid level system as shown in figure1, the pump removes waterat a constant rate of 10 m3/min and this rate is independent of head. The crosssectional area of the tank is 1 m2 and the resistance is 0.5 m/m3/min. Derive thetransfer function H(S)/Q(S) when
(a) The tank level operates about the steady state value of hs= 1 m.
(b) The tank level operates about the steady state value of hs = 3 m. [8+8]Figure 1:

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 forThermometer bulb and well arrangement. [6+10]

3. (a) what is meant by differential gap and how it is related to the performance ofthe final control element?
(b) Define proportional band. Explain the relation between proportional gain,proportional band and offset error.
(c) With a neat sketch explain the integral controller mode action. Summarizethe characteristics. [5+5+6]

4.(a) What are the advantages of the force type pneumatic controllers? Describewith neat diagrams, the working of a force type pneumatic proportional con-troller.
(b) Explain the working principle of a hydraulic proportional controller. Howproportional gain can be adjusted in this controller? [8+8]

5. (a) What is a optimum - tuning control? What are its different approaches?(b) How are the interactions in control being channelized to optimize the controlaction in a boiler? [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 diameterpipe. The constriction constant is 0.008 w3/s/(kPa)1/2. Findi. the flow rate in m3/sec.ii. flow velocity in m/sec. [8+8]

7. Write about the rotating shaft valves? [16]

8. Draw the feed forward and feed back control systems that regulate the flow throughthe pipe? Discuss about both the control systems and give reasons to select any ofthe two systems in maintaining the desired flow? [16]

INSTRUMENTATION & PROCESS CONTROL Question Papers (Regular, 2005)

SET :1

1. (a) What is called a ”Dead End System”? Explain one such system with neat diagram.

(b) Write the differential equation of this system and get the transfer function.

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. (a) What is meant by differential gap and how it is related to the performance of the final control element?

(b) Define proportional band. Explain the relation between proportional gain, proportional band and offset error.

(c) With a neat sketch explain the integral controller mode action. Summarize the characteristics.

4. (a) Develop an electronic two position controller with 0-5 volts input and a 0.0 or10.0 volt output. The set point is 2.5v and the neutral zone is to be 1v about this setpoint.

(b) A proportional pneumatic controller has equal area bellows. If 3-15 psi signals are used on input and output, find the ratio of pivot distances that provides a 25%proportional band.

5. Illustrate with relevant graphs the following methods of optimum settings from the plant response.

(a) Damped oscillation method.

(b) Reaction - curve method.

6. Explain the principle of a direct and reverse pneumatic actuator.

7. (a) Briefly explain valve sizing.

(b) A fully open valve passes 200gpm of water at a pressure differential of 10.0psicalculate valve sizing.

8. Write short notes on

(a) Feed forward control

(b) Override control

(c) Ratio control.

SET :2

1. System 1 and system 2 have resistances equal to 1 and 2 respectively. The capacitance of system 1 is 1 where as for the system 2, it is 2.

(a) Determine the time constants of System 1 and system 2.

(b) Forming a dead end interacting system with System 1 and 2, determine the overall transfer function.

(c) Determine the effective time constants of this interacting system.

2. (a) Give one example for Interacting first order elements in series.

(b) Write the differential equation for this combination and determine the transfer function.

(c) Comment on the transfer function.

3. (a) Explain with a neat sketch depicting the error vs controller output, the principle of a proportional controller action.

(b) With an example, explain how offset error in proportional controller occurs. Suggest a way to overcome the offset error.

4. (a) With a neat circuit diagram, explain the realization of an electronic two position controller with adjustable neutral zone.

(b) Design an electronic proportional controllers for (0-12v) error input, 10% proportional band and 50% zero error controller output.

5. (a) Plot the transient response of a process with time constants of 50sec and20sec and a time delay of 10sec. Use the reaction curve method to obtain the recommended settings for a three mode controller.

(b) What is the phase margin for the recommended controller gain?

6. (a) An equal percentage control valve has a range ability of 32. If the maximum flow rate is Find the flow at 2/3 and 4/5 open settings. 100ms3/hr.

(b) Explain
i. quick opening
ii. linear
iii. equal percentage characteristics of a control valve.

7. Write steps followed in choosing a valve for better control of flow and should be cost effective.

8. Explain feed forward control for the following

(a) Heat exchangers

(b) Drum boiler

SET :3

1. A Cylindrical tank with an area of 20ft2 and a height of 10 ft has a normal liquid depth of 6ft. The flow to the tank is10±1cubic ft/min, and the liquid is discharged through a control valve to a process at atmospheric pressure. (1 ft = 0.305 metre)Calculate the time constant if the tank is

(a) Open to the atmosphere

(b) Closed, with a constant pressure of 10 psig above the liquid.

(c) Closed, with a fixed amount of air sealed above the liquid. The initial pressure is 10 psig.

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.

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.

4. (a) Explain the method of realizing an electronic PI controller employing delayed positive feedback. Derive the expression for proportional gain and integral time.

(b) Explain with a neat sketch, the working principle of a moving vane type two position controller.

5. (a) Explain the detailed procedure for Ziegler - Nichols method PID settings. In the Ziegler - Nichols method, the critical gain was found to be 4.2 and the

(b) critical period was 2.21 minutes. Find the standard settings for
i. Proportional mode control
ii. PI control
iii. PID control.

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 0.008w3/s/(kPa)1/2. Find
i. the flow rate in m3/sec.
ii. flow velocity in m/sec.

7. (a) The area of opening of a valve versus lift is given by A = a + bx2. Derive the flow versus lift characteristic for this parabolic valve?

(b) Liquid Glycerin (density78lb/ft3) is require at a maximum flow of 18gpm. The line drop is 40 psi and the valve pressure drop is 10 psi what size plug valve is required?

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

SET : 4

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 0.136to 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 com-pare with the transfer function relating level and input flow

2. Differentiate between a continuous process and a batch process. Support your answer explaining with one continuous process and one batch process with neat diagrams.

3. a) Discuss the effects of an integral controller on the closed loop response of first order process.(b) With neat sketches, explain the principle of derivative control action. Summarize its characteristics.

4. (a) Briefly explain the principle of operation of a displacement type pneumatic PD controller. How the derivative time can be adjusted in this controller.

(b) Outline the design steps involved in developing an electronic PI controller.

5. (a) Discuss in brief the frequency response method of process controller tuning with Bode plot.

(b) In an application of the Ziegler - Nichols method; a process begins oscillation with a 30% proportional band in an 11.5min period. Find the normal three ?mode controller settings.

6. (a) Explain the baffle -Nozzle system with the help of its characteristic curves.

(b) Explain the pneumatic booster and what is its need.

(c) Differentiate between direct and reverse action final control operation.

7. (a) Centrifugal pump is available as a fluid source for a heat exchanger. At maxi-mum flow the head is 100 psig, and at shut off the head is 40psig. At maximum flow, line losses are 15 psi and the heat exchanger pressure drop is 75psi. The control valve back pressure is atmospheric. Can this pump be used?

(b) Explain about flashing problem in control valves.

8. Discuss the rational of cascade control and demonstrate why it provides better performance than feed back control?

INSTRUMENTATION AND BIOPROCESS CONTROL syllabus, JNTU (2007-2008)

UNIT I: PROCESS DYNAMICS

Process variables-Load variables-Dynamics of simple processes. Flow, level, temperature and pressure

UNIT II:

Interacting and non-interacting system, continuous and batch process-self - regulation-Servo and regulator operation problems.

UNIT III: CONTROL ACTIONS AND CONTROLLERS

Basic control actions-characteristics of two position, three position, proportional, single speed floating. Integral and derivative control modes- P+I. P+D and P+I+D control modes.Problems on pneumatic, hydraulic and electronic controllers to realize various control actions.

UNIT IV: OPTIMUM CONTROLLER SETTINGS

Evaluation criteria, 1/4th decay ratio, IAE. ISE, ITAE- determination of optimum settings for mathematically described process using time response and frequency response.

UNIT V:

Tuning process reaction curve method-continuous, oscillation method-damped oscillation method-problems.

UNIT VI: FINAL CONTROL ELEMENT

I/P Converter-pneumatic, electric and hydraulic actuators- valve positioner- control valves-characteristics of control valves-valve body-Globe, butterfly, diaphragm; Ball valves- Control valve sizing-Cavitation, flashing problem.

UNIT VII: MULTI LOOP CONTROL SYSTEM

Feed forward control-Ratio control-Cascade control-Split range-Multivariable control and examples from distillation column & Boiler system.

UNIT VIII:BIOSENSORS

Types, Transducers in biosensors- calorimetric, optical, potentiometric / amplometric, conductometric/ resistometric, piezoelectric, semi conductor, mechanical and molecular electromics based, molecular wires and switches, development of molecular arrays as memory stores, design for a biomolecular photomic computers- information processing.

TEXT BOOKS:

1. Process control, Pollard A. Heinemann, Educational Books. London, 1971.

2. Process control, Harriott P., Tata McGraw- publishing Co. New Delhi. Reprint 1991.

3. J.R. Leigh: Modeling and control in bioprocesses

4. JE Pearson, A Gill and P. Vadgama, Analytical aspects of biosensors, Annual Clinical Biochemistry 37, 119-145.

4. Patranabis, Process Control year?

5. KR Rogers, M. Mascion, Biosensors for analytical monitoring EP & biosensors year

6. Donald R. Coughanowr, Process Systems Analysis and Control, McGraw-Hill,1991

REFERENCES:

1. Automatic process control, Eckman D.P., Wiley Eastern Ltd. New Delhi. 1993.

2. Chemical Process Control Stephanoupoulis, G., Prentice Hall, New Delhi.

1990