Olefin Oligomerization Recycle Stream Control
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Solution Overview
Problem
Conventional olefin oligomerization processes for producing hydrocarbon fuels, such as jet fuel and diesel fuel, face inefficiencies in producing lighter distillate products due to high recycle rates and complex separation processes, which increase energy consumption and require larger equipment, while also complicating the production of lighter fuels like jet/kero and No. 1 Diesel.
Innovation Solution
A process involving the oligomerization of C3 to C8 olefins with a molecular sieve catalyst, where the olefinic recycle stream contains no more than 10 wt% C10+ non-normal olefins, allowing for the production of lighter hydrocarbon products by controlling the weight ratio of components in the recycle stream, and subsequent separation into lighter and heavier streams for recycling and product streams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a relatively large amount of olefinic recycle containing significant quantities of C10+ material is employed to produce heavy distillate products, then the production of heavy materials is improved, but the equipment size and energy consumption increase
Solution Approach 1:
The patent changes the compositional parameters of the recycle stream by limiting C10+ material to less than 10 wt% and controlling the C4-/C5-C8 weight ratio to 0.8-1.2 times the effluent ratio. This parameter modification enables lighter distillate production (jet fuel, kerosene, No. 1 Diesel) while reducing equipment size requirements compared to conventional heavy distillate processes
Solution Approach 2:
The patent segments the separation process into multiple stages with specific fractionation steps that separate the effluent into lighter olefinic stream and hydrocarbon product stream. This segmentation allows for more efficient separation of lighter products, reducing the need for oversized equipment compared to single-stage separation of heavy products
2Reliability
If a high rate of recycle is used to control the exotherm of the oligomerization reaction, then the reaction control is improved, but the energy consumption and equipment size increase
Solution Approach 1:
The patent modifies the recycle stream parameters to limit heavy ends (C10+) to less than 10 wt% and controls the molecular weight distribution through the C4-/C5-C8 weight ratio parameter. This enables effective exotherm control with lower recycle rates, reducing energy consumption while maintaining reaction reliability
3Duration of action of stationary object
If various components are introduced with the feed to prolong catalyst cycle life, then the catalyst stability is improved, but the separation complexity increases
Solution Approach 1:
The patent controls the compositional parameters of the feed and recycle streams to maintain catalyst stability without requiring additional components that would complicate separation. By optimizing the olefin composition and molecular weight distribution within specified ranges, the process achieves catalyst cycle life extension with simpler separation architecture
4Productivity
If the dense distillate product with high specific gravity and high viscosity is produced, then the heavy distillate production is improved, but the fractionation tower temperature requirements increase
Solution Approach 1:
The patent changes the product composition parameters by limiting C10+ material to less than 10 wt% and controlling the molecular weight distribution. This produces lighter distillate products (jet fuel, kerosene, No. 1 Diesel) with lower specific gravity and viscosity, eliminating the need for high-temperature fired heaters and reducing fractionation tower temperature requirements
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 simplifies and enhances the production of lighter distillate products like jet fuel and kerosene, reducing energy consumption and equipment size, while maintaining the quality of the hydrocarbon products, and allows for the production of blendstocks suitable for higher value fuels.
Implementation Method 1
contacting a feed stream and an olefinic recycle stream with a molecular sieve catalyst in a reaction zone under olefin oligomerization conditions to produce an oligomerization effluent stream
Implementation Method 2
separating said oligomerization effluent stream to produce a first olefinic stream and a first hydrocarbon product stream
Data Source
AI summary
A process for producing a hydrocarbon composition that comprises contacting a feed stream, that comprises at least one C3 to C8 olefin, and an olefinic recycle stream, that comprises a first olefinic recycle stream and no more than 10 wt % of C10+ non-normal olefins, with a molecular sieve catalyst in a reaction zone under olefin oligomerization conditions producing an oligomerization effluent stream; separating the oligomerization effluent stream to produce a first olefinic stream, that has a weight ratio of C4−/(C5-C8) molecules from about 0.8 to about 1.2 times the weight ratio of C4−/(C5-C8) molecules found in the oligomerization effluent stream, and a first hydrocarbon product stream, that comprises at least 1 wt % and no more than 30 wt % of C9 non-normal olefin; and splitting the first olefinic stream to produce the first olefinic recycle stream and a first purge stream.