Upfront Isomerization Zone for Stable Butane Alkylation Feed
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Solution Overview
Problem
Existing processes for producing C4 olefins and alkylate gasoline are inefficient, requiring additional equipment and utilities, and are not flexible with respect to fresh butane feedstock composition, leading to suboptimal octane-barrel yield and increased capital and operating costs.
Innovation Solution
Incorporating an upfront isomerization zone to convert 100% n-butane into a 60 wt% isobutane and 40 wt% n-butane blend, which is then fed to a dehydrogenation zone, followed by an alkylation zone, eliminating the need for a feed deisobutanizer and optimizing feedstock composition stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an upfront isomerization zone is incorporated to convert n-butane into isobutane blend, then C4 retention to olefins is enhanced and octane-barrel yield is increased, but device complexity increases due to additional isomerization equipment
Solution Approach 1:
The isomerization zone is placed upstream of the dehydrogenation zone to pre-convert n-butane into isobutane before dehydrogenation occurs. This preliminary action ensures that the dehydrogenation zone receives optimized feedstock composition (60 wt% isobutane and 40 wt% n-butane), which enhances C4 retention to olefins and increases octane-barrel yield without requiring downstream adjustments
Solution Approach 2:
The isomerization zone changes the compositional parameters of the feedstock by converting n-butane into isobutane, achieving a specific blend ratio (60 wt% isobutane and 40 wt% n-butane) that optimizes subsequent dehydrogenation and alkylation processes. This parameter change resolves the contradiction by improving productivity through controlled composition modification
2Stability of the object's composition
If feed deisobutanizer is used to separate isobutane from n-butane, then feedstock composition can be controlled, but capital costs and operating costs increase
Solution Approach 1:
The isomerization zone performs the composition control function upstream, converting n-butane into isobutane to achieve the desired feedstock composition stability before the dehydrogenation zone. This eliminates the need for a downstream feed deisobutanizer, thereby maintaining composition stability while reducing capital and operating costs
Solution Approach 2:
The invention extracts and eliminates the feed deisobutanizer from the process flow by performing the necessary composition control function in the upstream isomerization zone. This removal of unnecessary equipment reduces both capital costs and operating costs while maintaining the required feedstock composition stability
3Device complexity
If dehydrogenation is performed on 100% n-butane feed, then process simplicity is maintained, but C4 retention to olefins is reduced and n-butane recycle increases
Solution Approach 1:
The isomerization zone performs a preliminary conversion of n-butane into isobutane before dehydrogenation, creating an optimized feed blend (60 wt% isobutane and 40 wt% n-butane). This preliminary action enhances C4 retention to olefins in the subsequent dehydrogenation zone while maintaining overall process simplicity through integrated design
Solution Approach 2:
The isomerization zone changes the feed composition parameters to achieve optimal C4 retention to olefins during dehydrogenation. By controlling the isobutane-to-n-butane ratio in the feed, the system maximizes olefin production while minimizing n-butane recycle 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 configuration enhances C4 retention to olefins, reduces n-butane recycle, minimizes unreacted n-butane, and increases octane-barrel yield while reducing capital and operating costs.
Implementation Method 1
passing a hydrocarbon stream comprising n-butane to an isomerization zone to generate an isomerization zone product stream comprising a mixture of 60 wt% isobutane and 40 wt% n-butane
Implementation Method 2
The dehydrogenation zone product stream is passed to an alkylation zone to produce an alkylation zone product stream
Data Source
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AI summary
An alkylation process including an upfront isomerization zone is described. 100% n-butane or field butanes can be converted into a blend of 60 wt% isobutane and 40 wt% n-butane in the isomerization zone. This blend can be used as the feed to all types of alkylation zones. It stabilizes the feed composition so that the dehydrogenation zone and alkylation zone always operate with the same feed.