Hydrocracking Cycle Oil from FCC Slurry via Solvent Extraction
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Solution Overview
Problem
Fluid catalytic cracking (FCC) processes face challenges in recovering valuable hydrocarbons from clarified slurry oil (CSO), which are typically burned as fuel, and in upgrading these hydrocarbons to improve diesel quality, due to operational constraints and inefficiencies in the FCC main fractionation column.
Innovation Solution
Integrating an FCC unit with a hydrocracking unit to separate and hydrocrack the cycle oil stream from CSO, using a vacuum flash drum to recover lighter materials, which are then processed to produce additional diesel and petrochemical products, thereby upgrading the hydrocarbon quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LCO is withdrawn from the main fractionation column to cool the column and reduce coking, then column temperature is reduced and maintenance is reduced, but LCO is lost and not recovered
Solution Approach 1:
The patent extracts LCO from the CSO stream using a solvent extraction process. The solvent selectively dissolves LCO from the CSO, allowing LCO to be separated and recovered in the solvent phase while the remaining CSO continues to the hydrocracker. This resolves the contradiction by preventing LCO loss while maintaining the cooling function.
Solution Approach 2:
The patent recovers LCO that would otherwise be discarded or lost. By implementing solvent extraction, the process recovers LCO from the CSO stream and directs it to the hydrocracker unit, converting what was previously a loss into a valuable feedstock for diesel production.
2Ease of manufacture
If CSO is burned as fuel to dispose of it, then operational simplicity is maintained, but valuable hydrocarbons are lost
Solution Approach 1:
The patent extracts valuable hydrocarbons (LCO and HCO) from the CSO stream using solvent extraction. The solvent selectively dissolves these hydrocarbons, allowing them to be separated from the fuel-grade CSO and directed to the hydrocracker, thereby preventing their loss while maintaining operational simplicity.
Solution Approach 2:
Instead of discarding CSO as fuel, the patent recovers valuable hydrocarbons from it through solvent extraction and directs them to the hydrocracker unit for conversion into diesel and other valuable products.
3Reliability
If the FCC unit operates with extra LCO in CSO to prevent coking, then column temperature is reduced, but the refiner pays a penalty by losing additional LCO
Solution Approach 1:
The patent extracts LCO from the CSO stream using solvent extraction, allowing the FCC unit to operate with lower LCO content in CSO to prevent coking, while simultaneously recovering and directing the extracted LCO to the hydrocracker for valuable utilization.
Solution Approach 2:
The patent recovers LCO that would otherwise be lost due to coking prevention operations. By implementing solvent extraction, the process recovers LCO from the CSO stream and directs it to the hydrocracker unit, converting what was previously a loss into a valuable feedstock.
4Productivity
If cycle oil stream is hydrocracked to upgrade hydrocarbons, then diesel quality is improved and yield is enhanced, but process complexity increases
Solution Approach 1:
The patent merges the solvent extraction unit with the hydrocracker feed system. The solvent extraction process is integrated such that the extracted LCO and HCO are directly fed to the hydrocracker, combining two separate functions (extraction and hydrocracking) into a coordinated process that enhances diesel yield without proportionally increasing complexity.
Solution Approach 2:
The hydrocracker unit is positioned to receive multiple feed streams: conventional FCC feed, extracted LCO, and extracted HCO. This multi-functional approach allows a single unit to handle various feedstocks and maximize diesel production from all available hydrocarbon sources.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the recovery and upgrading of Light Cycle Oil (LCO) and Heavy Cycle Oil (HCO) from CSO, enhancing the yield of diesel and petrochemical products, reducing operational costs, and improving the flexibility of the FCC unit operations.
Implementation Method 1
The slurry oil stream is separated into a cycle oil stream and a heavy stream under vacuum pressure
Implementation Method 2
Hydrocracking is a hydroprocessing process in which hydrocarbons crack at the carbon-carbon bonds in the presence of hydrogen and hydrocracking catalyst
Implementation Method 3
Hydrocracking is a hydroprocessing process in which hydrocarbons crack at the carbon-carbon bonds in the presence of hydrogen
Data Source
AI summary
A process and apparatus for recovering cycle oil from FCC CSO is described. By feeding the additional cycle oil to a hydrocracking unit additional diesel, naphtha and petrochemical feedstock may be obtained. The additional cycle oil is obtained by vacuum separation of the CSO. The described process and apparatus can provide additional recovery for a refiner.