Integrated FCC Alkylation Eliminates Ethylene Splitter
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Solution Overview
Problem
Conventional Fluidized Catalytic Cracking (FCC) processes are energy-intensive and costly due to the need for an ethylene/ethane splitter column and high energy consumption in separating and recovering light olefins like ethylene, which are essential for producing valuable aromatics such as ethyl benzene.
Innovation Solution
An integrated process that catalytically cracks heavy hydrocarbon feedstocks to produce a combined ethylene/ethane stream, which is then reacted with benzene in an alkylation reactor to produce ethyl benzene, eliminating the need for an ethylene/ethane splitter and optimizing energy use by linking intercoolers with FCC process columns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an ethylene/ethane splitter column is used to separate ethylene from ethane in conventional FCC processes, then pure ethylene can be obtained for producing ethyl benzene, but capital costs and energy consumption increase significantly
Solution Approach 1:
The invention extracts only the necessary component (ethylene) from the mixed C2 stream by selectively reacting it with benzene in the alkylation reactor, while leaving ethane unreacted. This eliminates the need for energy-intensive separation while still obtaining the required ethylene for ethyl benzene production.
Solution Approach 2:
The alkylation reactor performs dual functions: it produces ethyl benzene from ethylene and benzene, and simultaneously acts as a selective separation device by consuming only ethylene and leaving ethane in the overhead stream. This multi-functionality eliminates the separate splitter column.
2Manufacturing precision
If an ethylene/ethane splitter column is installed in conventional FCC processes, then ethylene can be separated for aromatic production, but capital costs and maintenance costs increase
Solution Approach 1:
The invention merges the alkylation process with the ethylene separation function. The alkylation reactor is integrated with the FCC unit, and its overhead stream naturally provides separated ethane that can be recycled, eliminating the need for a separate splitter column and reducing overall process complexity.
Solution Approach 2:
The alkylation reactor serves itself by using the mixed C2 stream as feedstock, selectively consuming ethylene for product formation, and automatically providing separated ethane in the overhead stream for recycle. This self-service capability eliminates auxiliary separation equipment.
3Quantity of substance
If debutanized gasoline is used as solvent in the primary absorber, then C3+ hydrocarbons can be absorbed, but the demand for debutanized gasoline recycle increases energy consumption and costs
Solution Approach 1:
The invention recovers and reuses ethyl benzene column bottoms (a heavy aromatic stream) as a substitute for debutanized gasoline in the primary absorber. This discards a previously underutilized stream and recovers its absorption capability, reducing the demand for expensive debutanized gasoline recycle.
Solution Approach 2:
The invention changes the solvent parameter from debutanized gasoline to ethyl benzene column bottoms. This parameter change maintains the absorption function while utilizing a different material property profile, specifically leveraging the aromatic solvent's ability to absorb C3+ hydrocarbons without requiring extensive recycling.
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 reduces capital and energy costs by eliminating the ethylene/ethane splitter, decreases debutanized gasoline recycle demand, and enhances energy efficiency by using the ethyl benzene column bottoms as a solvent or co-feed, thereby lowering the duty of intercoolers and reboilers.
Implementation Method 1
contacting a heavy hydrocarbon feedstock with a hydrocarbon cracking catalyst in a fluidized reaction zone to produce a hydrocarbon effluent stream that includes ethane and ethylene
Implementation Method 2
reacting the ethylene of the combined ethane/ethylene stream with benzene to produce an ethyl benzene product stream
Data Source
AI summary
Processing schemes and arrangements are provided for obtaining ethylene and ethane via the catalytic cracking of a heavy hydrocarbon feedstock and converting the ethylene into ethyl benzene without separating the ethane from the feed stream. The disclosed processing schemes and arrangements advantageously eliminate any separation of ethylene from ethane produced by a FCC process prior to using the combined ethylene/ethane stream as a feed for an ethyl benzene process. Further, heat from the alkylation reactor is used for one of the strippers of the FCC process and at least one bottoms stream from alkylation process is used as an absorption solvent in the FCC process.