Hydrocarbon Isomerization Feed Segmentation for Yield and Hydrogen Savings
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Solution Overview
Problem
Current hydrocarbon isomerization processes face challenges in achieving high liquid yield and low hydrogen consumption, particularly when processing C5 and C6 hydrocarbons, as C7 hydrocarbons are subjected to cracking conditions, leading to lower isomerate yield and higher hydrogen consumption, and there is a desire to retain C6 rings to avoid conversion into high octane components.
Innovation Solution
A process involving the separation of feed streams into C5/C6 and C7+ hydrocarbons, where the C5/C6 stream is isomerized in the presence of a catalyst and hydrogen, and the C7+ stream is contacted with a benzene saturation catalyst to produce cyclohexane, with the resulting streams being processed through a stabilizer and de-isohexanizer column to enhance isomerate production and reduce hydrogen usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If C7 hydrocarbons are processed in the isomerization zone under conditions necessary to effectively isomerize C5 and C6 hydrocarbons, then isomerization of C5 and C6 hydrocarbons is achieved, but C7 hydrocarbons are subjected to cracking resulting in lower isomerate yield and higher hydrogen consumption
Solution Approach 1:
The hydrocarbon feed stream is segmented into two separate streams based on carbon number: a C5-C6 stream and a C7+ stream. The C5-C6 stream is directed to the isomerization zone for effective isomerization, while the C7+ stream is routed to the reforming zone. This segmentation prevents C7 hydrocarbons from undergoing cracking reactions in the isomerization zone, thereby maintaining high isomerate yield and reducing hydrogen consumption.
2Productivity
If C7 hydrocarbons are processed in the isomerization zone, then reforming capacity is utilized, but liquid yield from the C5/C6 isomerization zone decreases
Solution Approach 1:
The process segments the hydrocarbon feed into distinct C5-C6 and C7+ streams, directing each to its most suitable processing zone. The C7+ stream is exclusively processed in the reforming zone where it can be effectively converted to aromatic compounds, maximizing reforming capacity utilization. Simultaneously, the C5-C6 stream is processed in the isomerization zone, maximizing liquid yield from this zone by preventing C7 cracking.
3Temperature
If C6 rings are opened to convert into high octane components, then octane value increases, but liquid yield and hydrogen consumption are adversely affected
Solution Approach 1:
The process applies different quality treatments to different carbon number ranges: C5-C6 hydrocarbons undergo isomerization to preserve C6 rings and maintain liquid yield, while C7+ hydrocarbons undergo reforming to convert to aromatic compounds for high octane value. This local quality approach ensures that C6 rings are retained in the isomerization zone where they contribute to liquid yield, while octane requirements are met through the separate reforming of C7+ components.
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 increases the liquid yield from the C5/C6 isomerization zone and reduces hydrogen consumption while retaining C6 rings, resulting in improved isomerate production and capital expenditure savings by minimizing cracking of C7+ hydrocarbons and eliminating the need for additional columns.
Implementation Method 1
The first stream is isomerized in the presence of isomerization catalyst and hydrogen in an isomerization zone under isomerization conditions to produce an isomerized stream
Implementation Method 2
The second stream is contacted with a benzene saturation catalyst at benzene saturation conditions to produce a saturation effluent stream comprising cyclohexane
Data Source
AI summary
Processes and apparatus for isomerizing hydrocarbons are provided. The process comprises providing a feed stream comprising C5, C6 and C7+ hydrocarbons. The feed stream is separated to produce a first stream rich in C5 and C6 hydrocarbons and a second stream rich in benzene and C7+ hydrocarbons. The first stream is isomerized in the presence of isomerization catalyst and hydrogen in an isomerization zone under isomerization conditions to produce an isomerized stream. The second stream is contacted with a benzene saturation catalyst at benzene saturation conditions to produce a saturation effluent stream comprising cyclohexane.