Chemical Engineering Processes

Questions and Answers

What is the main advantage of the absence of the riser in the described reactor?

Increased thermal processes

Decreased catalyst efficiency

Higher coke formation

Reduced reaction zone (correct)

In the reaction process, the feed is injected at an angle to the catalyst flow.

False

What is injected into the first stage riser?

Fresh feedstock

The catalyst stripping is more efficient due to the __________ temperature present.

higher Signup and view all the answers

What type of feed is introduced in the second stage riser?

Heavy cycle oil Signup and view all the answers

The process described increases gas yield while decreasing gasoline yield.

False Signup and view all the answers

What facility is used for the separation of products from the catalyst?

Primary separator and cyclones Signup and view all the answers

Match the following components with their respective characteristics:

Fresh feedstock = Easy to crack but difficult to vaporize Heavy cycle oil (HCO) = Opposite adsorption and reaction properties Pre-stripped catalyst = Not treated with steam Regenerated catalyst = Combines with hot catalyst for cooler stream Signup and view all the answers

The catalyst/products separation occurs in two steps: inside a PRIMARY and externally in .

separator, cyclones Signup and view all the answers

Which substances were used as classical catalysts in the hydrogenation process?

Co, Mo, Ni, SULFIDES Signup and view all the answers

The first step of the process includes reactions that occur at high conditions.

False Signup and view all the answers

What are the two main steps in the developed two-stage process?

Desulfurization and deazotation in the first step; acidic catalyst with low hydrogenation activity in the second step. Signup and view all the answers

The process involves a _______ solution to keep the temperature at the right value.

aqueous amine Signup and view all the answers

Match the following components of the process with their functions:

High-Pressure Separator = Separates products from hydrogen Amine Scrubber = Removes H2S from gas Fractionator = Separates high-value products Hydrogenation Promoting Catalyst = Facilitates desulfurization and deazotation Signup and view all the answers

What role do nitrogen compounds and NH3 play in the process?

Inhibit the acidic sites Signup and view all the answers

The first reactor is filled with a catalyst that has high hydrogenation activity.

False Signup and view all the answers

What is the main product of interest produced from the low-pressure separator?

Diesel Signup and view all the answers

The gas resulting from the first stage can be ______ after being treated.

recycled Signup and view all the answers

Match the following stages with their characteristics:

First Step = Desulfurization and deazotation reactions Second Step = Low hydrogenation activity catalyst Gas Recycling = Temperature adjustment Recovery Process = Regeneration of amines Signup and view all the answers

Which of the following coking processes produces more gasoil?

Fluidised bed coking Signup and view all the answers

Asphaltenes are solid at room temperature.

True Signup and view all the answers

What is used to collect carbonaceous particles from combustion gases?

Cyclone Signup and view all the answers

Flexicoking allows around ____% of the feed to be converted into liquids and gas.

90 Signup and view all the answers

Match the following products with their respective yields in delayed and fluid coking:

Gas ≤ C4 = 7.5 (delayed) - 6.5 (fluid) Gasoline = 17 (delayed) - 10 (fluid) Gasoil = 53.5 (delayed) - 72 (fluid) Coke = 22 (delayed) - 11.5 (fluid) Signup and view all the answers

What is the main difference in the flexicoking process compared to other plants?

Introduction of a gasifier Signup and view all the answers

What is a primary benefit of using zeolites as catalysts in cracking processes?

They allow only small molecules to enter their pores. Signup and view all the answers

The use of zeolites in catalytic processes provides lower gasoline yields compared to other catalysts.

False Signup and view all the answers

What starting material can be used for hydrocracking besides hydrocarbons?

Cellulose Signup and view all the answers

The pretreatment of cellulose before hydrocracking involves using _____ to lower the molecular weights.

alcohol Signup and view all the answers

Match the catalytic properties of zeolites with their effects:

Strongly acidic catalytic sites = Enhanced cracking efficiency Uniform pore structure = Selective molecular access High stability and duration = Longer catalyst life Higher gasoline yields = Increased product output Signup and view all the answers

Which of the following is a feature of zeolites?

High stability and duration Signup and view all the answers

The presence of olefins and asphaltenes in feedstock does not affect yield.

False Signup and view all the answers

What is the yield range achieved after treating cellulose for hydrocracking?

C2-C9 yields around 89% Signup and view all the answers

Only certain products can exit active sites and move through channels, which is referred to as ______ selectivity.

product Signup and view all the answers

What role does the composition of the feedstock play in the hydrocracking process?

It influences the yields and catalyst effectiveness. Signup and view all the answers

What is the primary use of petroleum coke produced in the process?

Fuel in power plants Signup and view all the answers

High pressure water is used to cut petroleum coke from the drum.

True Signup and view all the answers

What temperatures are considered optimal for the coke in the reactor during the fluidized bed coking process?

500-550 °C Signup and view all the answers

The coker produces different fractions, which are separated in the __________ column.

rectifying Signup and view all the answers

Match the product with its subsequent process:

Fuel gas = Fuel application or other purposes Naphtha = Gasoline production Light Coker Gas Oil = Diesel processing Heavy Coker Gas Oil = Diesel processing Signup and view all the answers

What happens during the initial stage of the coking process?

The feed undergoes cracking Signup and view all the answers

The vapour that did not undergo cracking is sent to the rectifying column.

False Signup and view all the answers

What is done to the offline drum before it is opened to the atmosphere?

Steamed, vented, and cooled Signup and view all the answers

In the fluidized bed reactor, coke is kept in motion by a flow of __________ entering from the bottom.

steam Signup and view all the answers

What is the pressure range mentioned in the content for the cracking unit?

3-4 atm Signup and view all the answers

Study Notes

Catalytic Cracking and Separation Processes

FEED is injected perpendicular to catalyst flow, maximizing contact.
Products are separated through a two-step process: a PRIMARY SEPARATOR followed by CYCLONES.
Absence of a riser minimizes thermal processes, reducing reaction zone size and enhancing catalyst-product separation speed.
CATALYST STRIPPING efficiency increased by higher temperatures and lower hydrogen in coke, leading to more liquid yield.

Dual Risers Cracking System

Two risers operate at distinct temperatures and conditions, allowing optimization of selectivity and yields for light oils.
Fresh feedstock, easier to crack, is injected into the FIRST STAGE RISER, while HEAVY CYCLE OIL (HCO) is processed in the SECOND STAGE RISER.
Excluded part of the exhausted catalyst is mixed with regenerated catalyst to lower temperature.

RxCat FCC Technology

Incorporates pre-stripped catalyst combined with hot regenerated catalyst for improved conversion and selectivity at lower temperatures.
Higher catalyst/oil ratio achieved, boosting gasoline and propylene yields while reducing gas yield.
Utilizes catalysts containing Co, Mo, and Ni sulfides, sensitive to nitrogen compounds, inhibiting acid sites.

Two-Step Process

FIRST STEP involves desulfurization and deazotation to prevent catalyst deactivation; multiple fixed beds used to manage temperature.
SECOND STEP uses acidic catalyst with low hydrogenation activity, managing unreacted feed recycling and utilizing aqueous amine solutions for process stability.

Zeolite Catalysts

Zeolites are effective for catalytic cracking and hydrocracking due to strong acidic sites and uniform pore structure.
Their properties include high stability, selectivity for reagents/products, and superior gasoline yields based on molecular size restrictions.
Shape selectivity ensures molecules smaller than a certain size access active sites, promoting efficient conversion.

Hydrocracking of Biomass-Derived Materials

Cellulose derived from agricultural residues can be hydrocracked after a pretreatment in alcohol to lower molecular weights.
Achieves yields of C2-C9 compounds around 89%.

Feedstock Properties and Yield Considerations

Composition of feedstock is vital for maintaining yields and avoiding catalyst poisoning.
Presence of olefins and asphaltenes can hinder performance and result in financial losses.

Fluidized Bed Coking

Coke fluidized bed reactors are coupled with furnace-burner units to maintain coke motion and facilitate cracking at temperatures of 500-550 °C.
Vapor from cracking is separated into various fraction cuts; heavier fractions returned for further processing.
Generates more gasoil and less gasoline compared to delayed coking.

Flexicoking Process

Integrates a gasifier to enhance flexibility, converting around 90% of feed into liquids and gas.
Excess coke can be converted into gas for energy or chemical feedstock.

Asphaltenes Extraction

Asphaltenes, solid at room temperature, can reduce gasoil yield during cracking and hydrocracking if not removed.
Deasphalting processes recover non-asphaltene materials, improving overall yields and enabling fuel use in industries like cement and asphalt manufacturing.

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Description

Explore the mechanisms of catalyst flow and product separation in chemical engineering. This quiz covers key concepts such as thermal processes, catalyst stripping, and the roles of primary separators and cyclones. Test your knowledge on how these processes influence efficiency and yield.

Chemical Engineering Processes

Questions and Answers

What is the main advantage of the absence of the riser in the described reactor?

In the reaction process, the feed is injected at an angle to the catalyst flow.

What is injected into the first stage riser?

The catalyst stripping is more efficient due to the __________ temperature present.

What type of feed is introduced in the second stage riser?

The process described increases gas yield while decreasing gasoline yield.

What facility is used for the separation of products from the catalyst?

Match the following components with their respective characteristics:

The catalyst/products separation occurs in two steps: inside a PRIMARY __________ and externally in __________.

Which substances were used as classical catalysts in the hydrogenation process?

The first step of the process includes reactions that occur at high conditions.

What are the two main steps in the developed two-stage process?

The process involves a _______ solution to keep the temperature at the right value.

Match the following components of the process with their functions:

What role do nitrogen compounds and NH3 play in the process?

The first reactor is filled with a catalyst that has high hydrogenation activity.

What is the main product of interest produced from the low-pressure separator?

The gas resulting from the first stage can be ______ after being treated.

Match the following stages with their characteristics:

Which of the following coking processes produces more gasoil?

Asphaltenes are solid at room temperature.

What is used to collect carbonaceous particles from combustion gases?

Flexicoking allows around ____% of the feed to be converted into liquids and gas.

Match the following products with their respective yields in delayed and fluid coking:

What is the main difference in the flexicoking process compared to other plants?

What is a primary benefit of using zeolites as catalysts in cracking processes?

The use of zeolites in catalytic processes provides lower gasoline yields compared to other catalysts.

What starting material can be used for hydrocracking besides hydrocarbons?

The pretreatment of cellulose before hydrocracking involves using _____ to lower the molecular weights.

Match the catalytic properties of zeolites with their effects:

Which of the following is a feature of zeolites?

The presence of olefins and asphaltenes in feedstock does not affect yield.

What is the yield range achieved after treating cellulose for hydrocracking?

Only certain products can exit active sites and move through channels, which is referred to as ______ selectivity.

What role does the composition of the feedstock play in the hydrocracking process?

What is the primary use of petroleum coke produced in the process?

High pressure water is used to cut petroleum coke from the drum.

What temperatures are considered optimal for the coke in the reactor during the fluidized bed coking process?

The coker produces different fractions, which are separated in the __________ column.

Match the product with its subsequent process:

What happens during the initial stage of the coking process?

The vapour that did not undergo cracking is sent to the rectifying column.

What is done to the offline drum before it is opened to the atmosphere?

In the fluidized bed reactor, coke is kept in motion by a flow of __________ entering from the bottom.

What is the pressure range mentioned in the content for the cracking unit?

Study Notes

Catalytic Cracking and Separation Processes

Dual Risers Cracking System

RxCat FCC Technology

Two-Step Process

Zeolite Catalysts

Hydrocracking of Biomass-Derived Materials

Feedstock Properties and Yield Considerations

Fluidized Bed Coking

Flexicoking Process

Asphaltenes Extraction

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Description

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