JNTU
JNTU B.Tech III SURFACE PRODUCTION OPERATIONS Previous Question Paper (August/September - 2021 - R18)
Answer any five questions. All questions carry equal marks.
Main
With the help of a neat diagram, explain the working of a sliding stem control valve.
Answer
A sliding stem control valve is a type of final control element used to regulate fluid flow by moving a plug vertically within a valve body. The operation relies on the linear motion of a stem connected to a plug, which changes the size of the flow orifice between the plug and the seat.
The working mechanism involves the following components:
- Actuator: Typically a pneumatic diaphragm or piston that provides the force to move the stem.
- Stem: A rigid rod that transmits motion from the actuator to the valve plug.
- Plug: The internal trim component that restricts or allows flow based on its position relative to the seat.
- Seat: The stationary surface against which the plug seals to provide shut-off.
- Packing: A seal around the stem that prevents leakage of the process fluid to the atmosphere.
Operationally, when a control signal (e.g., 3-15 psi) is sent to the actuator, the diaphragm compresses or expands, moving the stem linearly. In a 'fail-closed' configuration, the actuator force pushes the plug against the seat to stop flow. As the signal changes, the stem lifts the plug away from the seat, increasing the flow area. The flow rate is determined by the plug's profile (linear, equal percentage, or quick opening), which dictates the relationship between stem travel and flow capacity.
Diagram description: The valve body is depicted with an inlet and outlet port separated by a central orifice. The plug is suspended vertically above the seat. The stem extends upward through a bonnet assembly containing the packing box, connecting to the actuator diaphragm housing at the top. The actuator spring provides the opposing force to return the valve to its fail-safe position.
Depict an overview of surface production operations using a flow diagram.
Answer
Surface production operations involve the processing of wellhead fluids to separate oil, gas, water, and impurities into marketable products. The process flow is as follows:
- Wellhead: Collects raw fluid from the reservoir.
- Manifold: Directs flow from multiple wells to processing equipment.
- Separation: Primary separation of oil, gas, and water using gravity-based separators.
- Treatment: Removal of water from oil (dehydration), gas sweetening/dehydration, and water treatment for disposal or injection.
- Storage and Metering: Final products are measured and stored in stock tanks or sent to pipelines.
Explain in detail the wellhead and manifold separation.
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Classify the separators used in surface facilities and enunciate their selection criteria.
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With the help of neat diagram, explain the construction and working of a two phase horizontal separator.
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What are the different selection considerations of two phase oil and gas separation?
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Derive the equation of horizontal three-phase separator.
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Discuss in detail the oil dehydrators with neat diagrams.
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Explain briefly the horizontal heater treaters.
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Explain the working of an electrostatic heater treater with the help of a neat diagram.
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Describe the indirect and direct fired heaters.
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Describe the single stage and double stage oil desalting system with the help of neat sketch.
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Discuss the stabilizer reboiler with neat diagram.
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Describe briefly the skim tanks and vessels with neat diagrams.
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Differentiate between pressure vs atmospheric vessels.
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