Vacuum Separator for FCC Slurry Oil Recovery
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Solution Overview
Problem
The FCC process generates clarified slurry oil (CSO) that is less valuable due to its heavy composition and high aromaticity, which degrades diesel quality and is not fully recovered, leading to operational inefficiencies and product losses.
Innovation Solution
Integrating an FCC unit with a hydrocracking unit to recover and upgrade CSO, using a vacuum separator to separate cycle oil from CSO, which is then fed back into the hydrocracking unit to produce lighter products like gasoline, kerosene, diesel, and petrochemicals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LCO flow rate is reduced and CSO flow rate is increased to lower main fractionation column temperature, then coking and maintenance needs are reduced, but LCO recovery is lost and product value decreases
Solution Approach 1:
The patent segments the CSO stream into multiple fractions using a side-cut fractionator, separating it into HCO (heavy cycle oil), LCO (light cycle oil), and CSO (clarified slurry oil). This allows selective recovery and routing of different hydrocarbon ranges to different destinations, enabling LCO to be recovered and sent to the diesel pool while HCO can be used for column cooling.
Solution Approach 2:
The patent introduces an intermediary side-cut fractionation unit between the main fractionation column and the final product destinations. This intermediary device enables the separation and selective routing of hydrocarbon fractions, allowing LCO to be extracted from the CSO stream and directed to appropriate product pools rather than being lost with the CSO.
2Duration of action of stationary object
If CSO is withdrawn with appreciable LCO and gasoline range hydrocarbons to prevent coking, then main fractionation column maintenance is reduced, but valuable hydrocarbons are lost in the CSO stream
Solution Approach 1:
The side-cut fractionator divides the CSO stream into distinct boiling range segments (HCO, LCO, and gasoline range), allowing each segment to be separately recovered and routed to appropriate destinations. This segmentation enables complete hydrocarbon recovery while maintaining column operation.
Solution Approach 2:
Instead of discarding the entire CSO stream as low-value fuel, the patent recovers valuable hydrocarbon components (LCO and gasoline range) from the CSO stream through side-cut fractionation. The recovered components are sent to appropriate product pools, maximizing resource utilization while minimizing waste.
3Quantity of substance
If LCO is directed to diesel pool, then diesel volume is increased, but diesel quality degrades due to high aromaticity and low cetane value
Solution Approach 1:
The patent applies local quality by directing different fractions to different destinations based on their properties. LCO with high aromaticity is directed to the diesel pool where volume is prioritized, while lighter, higher-quality gasoline range hydrocarbons are recovered and can be used elsewhere. This selective routing optimizes both quantity and quality considerations for different product pools.
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 process enables the recovery and upgrading of CSO components, enhancing diesel quality and increasing the yield of valuable products, thereby improving operational efficiency and reducing maintenance needs in the FCC main fractionation column.
Implementation Method 1
separating the slurry oil stream into a cycle oil stream and a heavy stream under vacuum pressure in a separator
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 to lower molecular weight hydrocarbons
Implementation Method 3
Hydrocarbon feed contacts catalyst in the reactor to crack the hydrocarbons down to smaller molecular weight products
Implementation Method 4
coke tends to accumulate on the catalyst which is burned off in the regenerator
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.