JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III PROCESS CONTROL INSTRUMENTATION Previous Question Paper (July - 2023 - R15)
Note: i) Question paper consists of Part A, Part B. ii) Part A is compulsory, which carries 25 marks. In Part A, Answer all questions. iii) In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions.
Part A
Define Self-Regulation.
Answer
Self-regulation is the inherent ability of a process to reach a new steady-state equilibrium following a change in input or load, without the need for external control intervention. A self-regulating process is characterized by a stable output that naturally balances itself against disturbances, typically represented by a process with a finite gain and a time constant.
What is meant by interacting systems? And mention examples.
Answer
An interacting system refers to a process configuration where the output of one stage or tank affects the input or behavior of the preceding stage. In such systems, the dynamics of each component are coupled, meaning the time constants and response characteristics are not independent; a change in the downstream process reflects back to the upstream process, complicating the overall transfer function.
Common examples include:
- Two or more liquid level tanks connected in series where the flow from the second tank depends on the head pressure of the first tank.
- Multi-stage heat exchangers where the outlet temperature of one stage influences the inlet temperature of the next.
- Distillation columns where multiple trays interact through vapor and liquid flow dynamics.
What are the different controllers used to realize the various control actions.
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Define differential gap and why is it introduced in a process.
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What are the Controller Tuning Methods?
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How could you choose evaluation criteria for an application?
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Explain the need of control valves sizing.
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Compare sliding stem and rotary stem control valves.
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Summarize the advantages of cascade control.
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What is meant by split range control? And mention applications of it.
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Part B
Explain Dynamics of flow processes with relations.
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What are the variables associated with Process Control? And describe them.
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Differentiate Continuous and Batch Processes.
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Explain about Non-Interacting systems with an example.
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Draw the functional diagram of Hydraulic PD control.
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Describe the characteristics of three position control.
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Explain about the Electronic PD controller with a neat sketch.
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Describe the characteristics of PI control action and its demerits.
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Differentiate ISE and IEA evaluation criteria’s.
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How could you determine the controller parameter settings for mathematically? Described process using Frequency response method.
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What is meant by tuning of controller parameters and explain about Continuous oscillations method.
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Enumerate PI controller settings recommended by Ziglers Nichols method.
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What is the need of P/I converter in control loops?
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Explain the operation of any one hydraulic actuator with a neat sketch.
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Explain the construction and operation of following control valves i) Globe valves ii) Diaphragm Valves.
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Compare Pneumatic and Hydraulic Actuators.
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Differentiate the inner and outer control loops of cascade control.
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How can you apply multivariable control to Distillation column? Explain.
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What is meant by ratio control? Explain it with simple example.
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Distinguish feedback and feed forward controls.
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