Integrated Hydrocracking and FCC System for Olefin Yield
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Solution Overview
Problem
Current hydrocracking and fluidized catalytic cracking processes lack flexibility and efficiency in producing high-value products like light olefins and middle distillates, with individual processes often resulting in suboptimal yields and product quality.
Innovation Solution
An integrated process combining hydrocracking and fluidized catalytic cracking, where hydrocarbon feedstocks are processed in multiple stages with specific catalysts and conditions to maximize the yield of light olefins and middle distillates, with the option to recycle unconverted bottoms for further hydrogenation and cracking, allowing for flexible operation based on hydrocracker conversion levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mild hydrocracking is used to reduce cost, then operating cost is reduced, but product yield and quality decrease
Solution Approach 1:
The hydrocracking process is divided into two separate reactors: a first reactor for initial hydrocracking and a second reactor for further cracking of bottoms. This segmentation allows each reactor to be optimized for different functions, with the first reactor producing middle distillates and the second reactor converting heavier fractions into additional middle distillates and light olefins, thereby increasing overall product yield while maintaining cost-effectiveness
Solution Approach 2:
The patent combines hydrocracking and fluidized catalytic cracking operations into an integrated two-stage process. The effluents from the first hydrocracking reactor are fed to a fractionator, with bottoms recycled to the second reactor. This merging of processes allows the system to achieve both the cost benefits of mild hydrocracking and the enhanced product yield of more severe cracking conditions
2Manufacturing precision
If hydrocracking severity is increased to improve product quality, then middle distillate quality improves, but operating cost increases
Solution Approach 1:
The cracking process is segmented into two reactors with different severity levels. The first reactor operates under mild hydrocracking conditions to produce initial middle distillates, while the second reactor operates under more severe conditions to further crack bottoms and produce additional middle distillates and light olefins. This segmentation allows quality improvement without proportionally increasing operating costs
Solution Approach 2:
The patent employs different operating parameters in each reactor, including temperature, pressure, and catalyst type. The first reactor uses conditions optimized for mild hydrocracking, while the second reactor uses conditions optimized for severe cracking. This parameter optimization in each stage allows quality improvement while controlling overall operating costs
3Productivity
If short contact time is used in FCC to increase light olefin yield, then light olefin production increases, but feed conversion decreases
Solution Approach 1:
The patent segments the cracking process into two stages: hydrocracking in the first reactor and fluidized catalytic cracking in the second reactor. The hydrocracking stage pre-processes the feed to reduce molecular weight and complexity, while the FCC stage with short contact time then efficiently produces light olefins. This segmentation allows both high feed conversion and high light olefin yield to be achieved
Solution Approach 2:
The first hydrocracking reactor performs preliminary cracking and hydrogenation of the feedstock before it enters the second FCC reactor. This preliminary action reduces the complexity and molecular weight of the feed, making it more suitable for the short contact time FCC process, thereby enabling both high conversion and high light olefin production
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 integrated approach enhances the yield of light olefins and middle distillates, offering greater flexibility in product slate adjustment and improving overall refinery efficiency by optimizing the conversion of hydrocarbon feedstocks across varying hydrocracker conversion levels.
Implementation Method 1
hydrocracking processes split the molecules of the feed into smaller, i.e., lighter, molecules having higher average volatility and economic value. Additionally, hydrocracking processes typically improve the quality of the hydrocarbon feedstock by increasing the hydrogen to carbon ratio and by removing organosulfur and organonitrogen compounds
Implementation Method 2
In fluidized catalytic cracking (FCC) processes, petroleum derived hydrocarbons are catalytically cracked with an acidic catalyst maintained in a fluidized state
Implementation Method 3
The effluents are passed to a fractionator column to separate the light gases, naphtha and diesel products boiling in the temperature range of 36° C. to 370° C.
Implementation Method 4
Coke deposited on the catalyst is burned off at high temperatures and in the presence of air prior to recycling regenerated catalyst back to the reaction zone
Data Source
AI summary
A system and method of cracking hydrocarbon feedstocks is provided that allows for significant flexibility in terms of the desired product yield. An integrated process includes introducing the feedstock and hydrogen into a first hydrocracking reaction zone containing a first hydrocracking catalyst to produce a first zone effluent. The first zone effluent and optionally additional hydrogen are passed to a second hydrocracking reaction zone containing a second hydrocracking catalyst to produce a second zone effluent. The second zone effluent is conveyed to a fractionating zone to at least a low boiling fraction and a high boiling fraction, and optionally one or more intermediate fractions. The bottoms fraction is passed to a fluidized catalytic cracking reaction and separation zone, from which olefins and gasoline are recovered. At least a portion of remaining cycle oil is passed from the fluidized catalytic cracking reaction and separation zone to the first and/or second hydrocracking reaction zone.