C4-C6 Hydrocarbon Isomerization Process with Stripping Zone
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Solution Overview
Problem
Traditional isomerization processes for C5 and C6 hydrocarbons are limited by high capital and utility costs due to the need for capital-intensive installations and significant utility usage for recycling isomerized C5 hydrocarbons, which restricts the conversion of normal pentane to isopentane.
Innovation Solution
A process that includes an isomerization reaction zone with a catalyst, followed by a stabilizer and stripping zone configuration to separate and recycle C5 hydrocarbons efficiently, minimizing the recycling of C4 hydrocarbons and reducing energy and capital expenses by utilizing a stripper column to separate isopentanes from normal pentanes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a deisopentanizer column is positioned in front of the isomerization unit to remove isomerized C5 hydrocarbons, then the conversion of normal C5 hydrocarbons to isopentane is improved, but the capital cost and utility requirements increase significantly
Solution Approach 1:
The process divides the separation function into two distinct zones: a deisopentanizer zone that removes isomerized C5 hydrocarbons from the fresh feed, and a stripping zone that separates C4 hydrocarbons from the recycled stream. This segmentation allows each zone to be optimized independently, reducing the complexity and capital cost compared to a single large separation unit.
Solution Approach 2:
The patent introduces a stripping zone as an intermediary separation unit between the isomerization reactor and the deisopentanizer. This intermediary zone selectively removes C4 hydrocarbons from the recycled stream, preventing them from interfering with the deisopentanizer's ability to separate C5 hydrocarbons, thereby enabling more efficient isomerization conversion without requiring overly complex separation equipment.
2Productivity
If sieves are installed on the product to remove normal pentane for recycling, then the recycling of isomerized C5 hydrocarbons is improved, but the capital cost and utility consumption increase
Solution Approach 1:
The patent replaces mechanical sieving equipment with a thermal stripping zone that uses temperature differential to selectively remove C4 hydrocarbons from the recycled stream. This thermal separation method eliminates the need for mechanical sieves and significantly reduces utility consumption while achieving the same recycling objective more efficiently.
Solution Approach 2:
The stripping zone utilizes changes in temperature and pressure parameters to selectively separate C4 hydrocarbons from C5 hydrocarbons in the recycled stream. By controlling these parameters, the process achieves efficient separation without requiring capital-intensive mechanical sieving equipment or excessive utility consumption.
3Reliability
If the equilibrium C5 isomerization ratio is reached in the reactor, then the octane upgrading is improved, but the conversion of normal C5 hydrocarbons is limited
Solution Approach 1:
The patent implements a feedback mechanism where the stripping zone continuously removes C4 hydrocarbons from the recycled stream and returns purified C5 hydrocarbons to the isomerization reactor. This feedback loop maintains favorable conditions for isomerization by preventing C4 accumulation, allowing the reactor to operate closer to equilibrium without being limited by product inhibition, thereby improving both octane upgrading and conversion efficiency.
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 allows for the efficient recycling of C5 hydrocarbons while minimizing energy and capital expenditures, enhancing the conversion of normal pentane to isopentane without undue increases in costs.
Implementation Method 1
contacting the feed stream in an isomerization reaction zone with an isomerization catalyst at isomerization conditions to produce an isomerization zone effluent
Implementation Method 2
passing at least a portion of the isomerization zone effluent to a stabilizer zone and recovering a stabilizer overhead stream, a bottom stream, and a stripper feed stream
Implementation Method 3
passing the stripper feed stream to a stripping zone and separating the stripper feed stream into a stripper overhead stream and a stripper bottom stream
Data Source
AI summary
One exemplary embodiment can be a process for isomerizing a feed stream including one or more C4-C6 hydrocarbons. The process may include contacting the feed stream in an isomerization reaction zone with an isomerization catalyst at isomerization conditions to produce an isomerization zone effluent; passing at least a portion of the isomerization zone effluent to a stabilizer zone and recovering a stabilizer overhead stream, a bottom stream, and a stripper feed stream; passing the stripper feed stream to a stripping zone and separating the stripper feed stream into a stripper overhead stream and a stripper bottom stream; and recycling at least a portion of the stripper bottom stream to a deisopentanizer zone and passing a stream from the deisopentanizer zone to the isomerization reaction zone. Usually, the stabilizer overhead stream includes one or more C5− hydrocarbons, the bottom stream includes at least about 85%, by weight, one or more C6+ hydrocarbons, and a stripper feed stream including at least about 10%, by weight, one or more C5+ hydrocarbons. Often, a stripper overhead stream includes at least about 5%, by weight, one or more C4− hydrocarbons and a stripper bottom stream includes at least about 90%, by weight, one or more C5+ hydrocarbons.