Questions and Answers
What is the primary function of the riser in the catalytic cracking process?
The catalytic cracking process operates at temperatures below 500 °C.
False
Which impurities are commonly found in residues?
What is used in the catalyst stripper to improve the removal of products from catalyst particles?
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The Conradson carbon index for catalytic cracking residues should be higher than 15%.
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What types of processes are considered hydrogenation processes?
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Coke is removed from the catalytic surface by burning it in the _____________ at temperatures around 680°C - 720°C.
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Match the following components with their respective roles in the catalytic cracking process:
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Coke deposition on catalysts during catalytic cracking is more _____ than in normal gasoil catalytic cracking.
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Match the following impurities with their effects on yield:
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What technological innovation helps to minimize non-selective thermal cracking?
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What is the purpose of cooling systems within the regenerator unit of modern reactors?
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Air combustion in the regenerator heats catalyst particles to necessary temperatures.
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Residue catalytic cracking requires special catalysts due to low metal content in feed.
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What is the typical diameter range of the riser used in the catalytic cracking process?
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The temperature range for burning coke in the regenerator is ___________ °C.
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Give an example of a thermal (T) process in the context of carbon removal.
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Which of the following products is NOT included in the lighter fractions separated in the fractionator?
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Catalytic cracking is suitable for residues with a Conradson carbon index lower than _____%.
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What main advantage does the high severity down flow FCC process have over traditional methods?
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The hydrocracking process operates under milder conditions without the formation of coke.
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Name one concern associated with excessive catalyst loading.
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The addition of ________ in the hydrocracking process leads to a more flexible process.
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Match the following terms related to hydrocracking with their descriptions:
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What is a consequence of high catalyst circulation in the down flow FCC process?
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Single stage hydrocracking typically achieves high conversion rates above 60%.
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What type of catalysts are commonly used in the hydrocracking process?
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The high severity down flow FCC process requires higher temperatures around ________ degrees Celsius.
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Which of the following is NOT a concern identified in the high severity down flow FCC process?
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Which compound is NOT produced through steam cracking?
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The choice of feedstock for steam cracking does not have to consider market demand.
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What type of bonds are broken during the thermal cracking process?
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Steam cracking operates at high temperatures around _______ °C.
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Match the following products with their respective annual production quantities:
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What is a significant advantage of using DAO STRIPPER and asphaltenes stripper for solvent recovery?
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What is the main goal of the deasphalting process in lube oil manufacture?
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The yield of deasphalting processes typically ranges from 75% to 85%.
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What are light paraffins used for in the deasphalting process?
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The solvent used for supercritical extraction is often _____ for optimal results.
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Match the following terms with their descriptions:
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Which of the following is a characteristic of supercritical extraction processes?
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Increasing the extraction pressure enhances the solubility of asphaltenes.
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What happens to the metal content during the deasphalting process yield increase?
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The process used to figure out the best compromise between DAO yield and _____ is important.
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What is one of the main benefits of using supercritical fluids in extraction?
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Study Notes
Components and Impurities in Residue
- Residue consists of saturates, aromatics, resins, and asphaltenes.
- Common impurities include sulfur (S), nitrogen (N), and heavy metals.
- "Residue" encompasses distillation residues, heavy oils, bitumen, and tar sands.
Hydrocracking and Hydrogenation Processes
- Hydrocracking is a catalytic cracking process involving hydrogen, allowing use of less valuable feeds like crude oil.
- It requires higher operational and investment costs due to hydrogen needs.
- Milder cracking conditions prevent coke formation, leading to olefin saturation and effective desulfurization.
Catalytic Cracking of Residue
- Improvements in gasoil fluid catalytic cracking (FCC) enable higher gasoline yield.
- Special catalysts are necessary due to the presence of metals in the feed.
- Nickel (Ni) and vanadium (V) levels must be monitored; exceeding 10-30 ppm may necessitate hydrogen treatment.
- Coke formation from Ni reduces liquid yield and from V lowers conversion and yield.
Catalyst Regeneration and Efficiency
- Catalyst coking is more common in residue catalytic cracking compared to gasoil.
- Modern reactors utilize cooling systems and regeneration units to manage excess heat.
- A Conradson Carbon Index lower than 15% makes residue suitable for catalytic cracking.
Riser and Reactor Design
- The preheated feed enters a riser (200 t/hour) that facilitates catalytic cracking within 2-4 seconds at temperatures over 500°C.
- Catalyst particles combust in the regenerator at 680°C - 720°C, with air enhancing temperature.
- The catalyst stripper uses steam to aid product removal from catalyst surfaces, assisted by cyclones.
Product Separation
- Products from catalytic cracking are separated in a fractionator, sorting lighter fractions (C1-C2, gasoline, propane, butane) from heavier oils and slurries.
- Non-selective thermal cracking can occur based on temperature and residence time despite plant designs minimizing this effect.
Advanced Catalytic Cracking Techniques
- Millisecond Catalytic Cracking (MSCC) reactor design mitigates non-selective post-riser cracking and enhances gasoline selectivity.
- High Severity Down Flow FCC combats back-mixing by utilizing down flow to improve contact efficiency with catalysts.
- Understand concerns with excessive catalyst loading, circulation, and fines generation that could affect efficiency and emissions.
Deasphalting Processes
- The single-stage process for hydrocracking leads to low conversion rates but aims for asphaltenes removal and increased gasoil yields.
- The multistage deasphalting unit leverages different solubility in solvents, primarily using light paraffins, yielding deasphalted oil (DAO).
Residuum Oil Supercritical Extraction (ROSE)
- ROSE process utilizes supercritical solvents, like CO2, yielding high asphaltene extraction rates with lower costs.
- Supercritical solvents enhance extraction and phase separation rates significantly compared to standard methods.
- DAO separation generates low MW paraffins while heavier fractions remain in the asphaltenic product.
Steam Cracking Overview
- Steam cracking is pivotal in producing ethylene (140 million t/a), propylene (70 million t/a), and C4 olefins.
- Feedstock choices include naphtha, natural gas, and ethane, dictated by market demand.
- This thermal cracking process breaks high MW molecules at temperatures around 900°C, facilitating radical mechanisms.
Steam Cracking Radical Mechanism
- High temperatures induce homolytic bond breaking in large molecules, leading to β-cleavage.
- This process generates ethylene and propylene through radical transformations, capitalizing on the energy difference between primary and secondary radicals.
- Increased molecular entropy drives the reaction, necessitating steam addition to lower hydrocarbon pressures.
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Description
This quiz covers the key components and impurities found in petroleum residues, including saturates and aromatics. It also explores hydrocracking and catalytic cracking processes used to refine crude oil more efficiently. Test your understanding of the effects of impurities on refining and the technologies involved.
