Petroleum Refining Process

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Questions and Answers

What is the primary purpose of the scrubber in the continuous coking process?

To maintain the reactor temperature and sustain thermal cracking reactions

To separate the liquid products from the reactor effluent

To produce a clean fuel gas (Flexigas) for boilers and furnaces

To condense higher boiling hydrocarbons and recycle them to the reactor (correct)

What is the percentage of coke produced in the reactor that is burned to provide heat?

80-90%

50-60%

20-25% (correct)

10-15%

What is the main difference between continuous coking and batch-coking technology?

The type of feed used in the process

The products formed in the process

The temperature of the reactor

The fact that coke particles are in a continuous system (correct)

What is the primary purpose of the reactor in the continuous coking process?

To thermally crack the feed to a full range of liquid products and coke Signup and view all the answers

What is the purpose of the heater in the continuous coking process?

To burn coke to provide the heat necessary for the cracking process Signup and view all the answers

What is the percentage of coke produced in the reactor that is consumed in the process?

97% Signup and view all the answers

What is the purpose of the gasifier in the continuous coking process?

To produce a clean fuel gas (Flexigas) for boilers and furnaces Signup and view all the answers

What is the main product of the continuous coking process?

Lighter products such as naphtha, kerosene, heating oil, and hydrocarbon gases Signup and view all the answers

What is the primary objective of the hydrocracking process?

To produce high-quality petroleum products with low sulfur and aromatic compounds Signup and view all the answers

What is the role of catalytic cracking in the hydrocracking process?

To scission carbon-carbon single bonds Signup and view all the answers

What is the relationship between cracking and hydrogenation in the hydrocracking process?

They are complementary reactions that enhance the overall efficiency of the process Signup and view all the answers

What is the primary reason for the shift in demand for petroleum products?

Increased demand for gasoline and jet fuel Signup and view all the answers

What is the benefit of hydrocracking in terms of by-products?

Production of by-product hydrogen at low cost and large amounts Signup and view all the answers

What is the mechanism of hydrocracking?

The combination of catalytic cracking and hydrogenation Signup and view all the answers

What is the purpose of the catalyst regenerator in the hydrocracking process?

To clean and recycle the spent catalyst Signup and view all the answers

What is the characteristic of all hydrocracking and hydroprocessing processes used today?

They are fixed bed catalytic processes with liquid downflow Signup and view all the answers

What is the primary purpose of the refining process in the context of crude oil?

To separate various fractions of crude oil Signup and view all the answers

What is the purpose of the desalter in the atmospheric distillation unit (ADU) process?

To remove impurities from the crude oil Signup and view all the answers

What is a catalyst?

A substance that causes reactions between other chemicals Signup and view all the answers

What is the advantage of using zeolite catalysts over amorphous synthetic silica alumina combinations?

Higher activity and lower coke yield Signup and view all the answers

What is the operating pressure of the atmospheric distillation unit (ADU)?

760 mmHg Signup and view all the answers

What is the temperature range of the crude oil after it is heated in the furnace in the ADU process?

399°C to 426°C Signup and view all the answers

What is the purpose of the regenerator in a Fluidized Catalytic Cracker?

To regenerate the catalyst Signup and view all the answers

What is the term used to describe the heaviest fractions of crude oil that leave the bottom of the atmospheric distillation column?

Residuum Signup and view all the answers

What is formed during the cracking phenomena in a Fluidized Catalytic Cracker?

Coke, smaller molecules, and a range of hydrocarbons Signup and view all the answers

What is the main component of the feedstock in a Fluidized Catalytic Cracker?

Long-chain hydrocarbons Signup and view all the answers

What is the purpose of the heat exchangers in the ADU process?

To heat the crude oil Signup and view all the answers

What is the purpose of the cyclones in a Fluidized Catalytic Cracker?

To extract the cracked hydrocarbon vapor Signup and view all the answers

What is the term used to describe the process of changing the size and/or structure of hydrocarbon molecules?

Conversion Signup and view all the answers

What is the term used to describe the groups of hydrocarbon compounds of differing boiling-point ranges?

Fractions Signup and view all the answers

What is the primary function of the fractionator in a Fluidized Catalytic Cracker?

To separate the cracked hydrocarbon vapor into different products Signup and view all the answers

What is the advantage of using zeolite catalysts in Fluidized Catalytic Cracking?

Lower coke yield and higher gasoline yield Signup and view all the answers

What is the approximate yield of polymer gasoline per barrel of olefin feed in the polymerization process?

0.7 barrels Signup and view all the answers

What is the primary function of the amine solution in the process?

To remove hydrogen sulfide and mercaptans from the feed Signup and view all the answers

What is the typical temperature range for the polymerization reaction?

300-425°F Signup and view all the answers

Why is it necessary to remove oxygen from the feed?

Because oxygen strongly affects the reactions Signup and view all the answers

What is the purpose of adding a small amount of water to the olefin feed steam?

To promote ionization of the acid Signup and view all the answers

What is the typical range of catalyst consumption rates?

1 lb/100-200 gallons of polymer produced Signup and view all the answers

What is the purpose of the silica gel or molecular sieve bed in the process?

To dry the feed Signup and view all the answers

Why is the polymerization reaction classified as highly exothermic?

Because it releases a large amount of heat Signup and view all the answers

Study Notes

Continuous Coking/Fluid Coking

Converts heavy residual crude into lighter products such as naphtha, kerosene, heating oil, and hydrocarbon gases
The "fluid" term refers to the fact that coke particles are in a continuous system versus older batch-coking technology
Simplified version of Flexicoking

Process Overview

Feed (565°C-plus vacuum resid) enters the scrubber for integrated direct contact heat exchange with reactor overhead efﬂuent vapors
Scrubber condenses higher boiling hydrocarbons in the reactor efﬂuent (525°C) and recycles these along with the fresh feed to the reactor
Lighter overhead vapors are sent to conventional fractionation and light ends recovery
In the reactor, feed is thermally cracked to a full range of liquid products and coke
Coke inventory is maintained by transferring bed coke from the reactor to the heater via a transfer line
Hot coke from the heater is circulated back to the reactor (through coke transfer line), supplying the heat necessary to maintain reactor temperature and to sustain thermal cracking reactions

Flexicoking

Excess coke is sent to the gasiﬁer where the coke reacts with air and steam to produce a clean fuel gas (Flexigas)
Approximately 97% of the coke generated in the reactor is consumed in the process, with a small amount of product coke recovered from the ﬁnes system

Catalysts

Acid-treated natural aluminosilicate
Amorphous synthetic silica alumina combinations
Crystalline zeolites @ molecular sieves
Commercial: Zeolite (USY zeolite), with higher activity, higher gasoline yields, and lower coke yield

Fluidized Catalytic Cracker (FCC)

Converts heavy residual crude into lighter products
Reactor/Riser, Catalyst, Regenerator, and Fractionator are the main components
Cracking phenomena:
- Formation of coke
- Formation of smaller molecules
- Smaller naphtenic+aromatic+olefins formed
- Cracking of large molecules
- Producing full range of HC

Objective

To convert heavy oil feedstock into high quality, lighter fuel products (gasoline, naphtha, kerosene, diesel, hydrowax) which can be used as petrochemical plant feedstock or lube basestock

Reasons

Demand for petroleum products has shifted to high ratios of gasoline and jet fuel compared to usage of diesel fuel and home heating oils
By-product hydrogen at low cost and large amounts
Limiting sulfur & aromatic compound in motor fuels have increased

Hydrocracking

Mechanism of hydrocracking is superimposed of catalytic cracking & hydrogenation
Catalytic cracking is the scission of a carbon-carbon single bond
Hydrogenation is the addition of hydrogen to a carbon-carbon double bond
Cracking & Hydrogenation are complementary processes:
- Cracking provides olefins for hydrogenation
- Hydrogenation provides heat for cracking
- Overall reaction provides excess heat → quenching unit

Two-Stage Hydrocracker

All hydrocracking & hydroprocessing processes are fixed bed catalytic processes with liquid downflow
Hydrocracking process may require either one or two stages depending upon the process and the feed stocks used

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Description

This quiz covers the steps involved in a petroleum refining process, including heat exchange, condensation, and thermal cracking. It describes the treatment of feed and reactor effluent, and the resulting products.