Light Paraffin Deisomerization via Hydrogen Removal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing processes for isomerizing light paraffins to increase the concentration of normal paraffins face challenges due to low conversion rates and equilibrium issues, particularly with C4 isomerization, where the presence of heavies and aromatic rings, along with high hydrogen partial pressure, inhibit C4 conversion.
Innovation Solution
A process involving the separation of hydrogen using a separator between C5 and C4 isomerization reactors to minimize hydrogen levels, followed by selective adsorption and fractionation to isolate normal paraffins, and subsequent isomerization under optimized conditions to enhance the yield of normal paraffins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If isomerization is performed under conventional conditions with high hydrogen partial pressure, then hydrogenation reactions are promoted, but C4 isomerization conversion is inhibited due to equilibrium limitations
Solution Approach 1:
The isomerization process is divided into two distinct stages: a first isomerization zone for C5+ isomerization followed by a second isomerization zone for C4 isomerization. This segmentation allows each zone to operate under optimized conditions - the first zone maintains higher hydrogen partial pressure for C5+ conversion while the second zone operates with lower hydrogen partial pressure to achieve equilibrium C4 conversion levels.
Solution Approach 2:
The process utilizes parameter changes by controlling hydrogen partial pressure differently in each isomerization zone. The first zone operates with higher hydrogen partial pressure to promote C5+ isomerization, while the second zone operates with reduced hydrogen partial pressure (achieved through steam injection or hydrogen removal) to enable C4 isomerization to reach equilibrium conversion levels.
2Manufacturing precision
If a series of fractionation columns are used to separate isoparaffins from normal paraffins, then separation purity is improved, but capital cost and process complexity substantially increase
Solution Approach 1:
The process segments the isomerization function into two distinct zones rather than using multiple fractionation columns for separation. Each zone targets specific paraffin components (C5+ in the first zone, C4 in the second zone), achieving effective separation through selective isomerization rather than through multiple physical separation stages.
Solution Approach 2:
The process replaces the mechanical separation system (multiple fractionation columns) with a chemical transformation system (two-stage isomerization). Instead of physically separating isoparaffins from normal paraffins through multiple distillation stages, the process chemically converts isoparaffins to normal paraffins in sequence, eliminating the need for complex fractionation infrastructure.
3Productivity
If isomerization conditions are optimized for C5 isomerization, then C5 conversion is improved, but C4 conversion is inhibited due to high hydrogen partial pressure
Solution Approach 1:
The isomerization process is divided into two distinct stages: a first isomerization zone for C5 isomerization followed by a second isomerization zone for C4 isomerization. This segmentation allows each zone to operate under optimized conditions - the first zone maintains higher hydrogen partial pressure for C5 isomerization while the second zone operates with lower hydrogen partial pressure to achieve equilibrium C4 conversion.
Solution Approach 2:
The first isomerization zone performs preliminary isomerization of C5+ isoparaffins to normal paraffins before the second zone processes C4 isomers. This preliminary action removes competing C5 isomers that would otherwise consume hydrogen and inhibit C4 isomerization equilibrium, allowing the second zone to operate more effectively.
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 concentration of normal paraffins by improving conversion rates and achieving equilibrium levels, thereby enhancing the yield of ethylene and propylene in steam cracking operations.
Implementation Method 1
separating the first isomerate stream into a first vapor isomerate stream and a first liquid isomerate stream
Implementation Method 2
selective adsorption and fractionation to isolate normal paraffins
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A process for increasing conversion and selectivity to normal paraffins is achieved by reducing the hydrogen to hydrocarbon ratio for paraffin feeds with substantial butanes. A separator may be used to remove excess hydrogen from a first isomerate before a second isomerization step that may isomerize additional butanes perhaps generated in the first isomerization step.