JNTU
JNTU B.Tech III PETROLEUM REFINERY ENGINEERING Previous Question Paper (February/March - 2022 - R18)
Answer any five questions. All questions carry equal marks.
Main
Draw the refinery flow diagram with all the processes performed in the refinery and mention all the products in the diagram.
Answer
A petroleum refinery flow diagram illustrates the transformation of crude oil into various marketable products through a series of physical and chemical processes. The process flow begins with the pretreatment of crude oil, followed by primary distillation, and subsequently, secondary conversion and finishing processes.
The refinery flow sequence is as follows:
- Desalting and Dehydration: Raw crude oil is treated to remove salts, water, and sediments to prevent corrosion and catalyst poisoning.
- Atmospheric Distillation Unit (ADU): The desalted crude is heated and separated into fractions based on boiling points. Products include light gases, naphtha, kerosene, diesel, and atmospheric residue.
- Vacuum Distillation Unit (VDU): The atmospheric residue is further distilled under vacuum to recover heavy gas oils (vacuum gas oil) and vacuum residue, preventing thermal cracking.
- Conversion Processes: Heavy fractions are upgraded into lighter, high-value products:
- Fluid Catalytic Cracking (FCC): Converts heavy gas oils into gasoline and light olefins.
- Hydrocracking: Uses hydrogen and catalysts to convert heavy distillates into high-quality jet fuel and diesel.
- Delayed Coking: Converts heavy vacuum residue into lighter products and petroleum coke.
- Reforming: Upgrades low-octane naphtha into high-octane gasoline blending components.
- Treating and Finishing: Processes like hydrotreating remove sulfur, nitrogen, and impurities from streams to meet environmental standards.
- Blending: Various streams are blended to produce final products such as Liquefied Petroleum Gas (LPG), gasoline, jet fuel, diesel, fuel oil, lubricants, and asphalt.
The final products obtained from the refinery include: LPG, Gasoline (Petrol), Naphtha, Kerosene, Aviation Turbine Fuel (ATF), Diesel (HSD), Fuel Oil, Lubricating Oils, Petroleum Coke, and Bitumen/Asphalt.
Explain the following terms:
Octane number and Cetane number with its significance
Answer
The Octane number is a measure of the antiknock quality of gasoline. It is defined as the percentage by volume of isooctane in a mixture of isooctane and n-heptane that matches the knocking characteristics of the fuel being tested in a standard engine. Its significance lies in preventing engine knocking or pre-ignition, which can cause mechanical damage and power loss in spark-ignition engines.
The Cetane number is a measure of the ignition quality of diesel fuel. It is defined as the percentage by volume of cetane (n-hexadecane) in a mixture of cetane and alpha-methylnaphthalene that matches the ignition delay of the fuel. Its significance is that a higher cetane number indicates a shorter ignition delay, leading to smoother combustion, easier cold starts, and reduced engine noise in compression-ignition engines.
Flash point and Fire point with its significance
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Explain the single and two-stage electrostatic desalting processes with the help of neat and clean diagram for each process.
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Explain the vacuum distillation unit and its accessories indicating the equipment involved in it and explain the process in detail.
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Describe the delayed coking process with the help of schematic diagram.
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What are the uses of petroleum coke?
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Explain the fluid catalytic-cracking with the help of neat and clean diagram.
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Demonstrate the Flexicoking process with the help of suitable diagram.
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Describe the process of moving-bed hydroprocessors. Write the advantages of moving bed hydroprocess.
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Illustrate the solvent extraction process with the help of neat and clean flow diagram.
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What are the parameters affects the alkylation processes. Explain in details.
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Explain the sources of waste water in refineries and its treatment process.
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