C5 Splitter Column for Isomerization Recycle Efficiency
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Solution Overview
Problem
Traditional isomerization units for C5 and C6 hydrocarbons face limitations in octane improvement due to high C5 content and require capital-intensive installations for recycling isomerized C5 hydrocarbons, leading to high utility utilization and inefficient conversion of normal pentane to isopentane.
Innovation Solution
A process that includes an isomerization reaction zone with a stabilizer and stripper zone configuration, allowing for the separation of effluent streams to recycle C5 hydrocarbons efficiently, minimizing the recycling of C4 hydrocarbons and reducing energy and capital expenses by using a C5 splitter zone 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 can be increased, but the capital cost and utility utilization increase significantly
Solution Approach 1:
The process separates the C5 hydrocarbon handling into distinct segments: the deisopentanizer removes isomerized C5 from fresh feed, while the C5 splitter selectively removes normal pentane from the recycle stream. This segmentation allows targeted removal of specific components at optimal points in the process, improving overall conversion without requiring a single complex unit
Solution Approach 2:
The C5 splitter acts as an intermediary device between the isomerization unit and the recycle system. It selectively separates normal pentane from the isomerized C5 stream, creating a purified recycle stream that can be fed back to the isomerization unit. This intermediary function enables efficient normal pentane conversion without the capital intensity of a full deisopentanizer in the recycle path
2Productivity
If sieves are used on the product to remove normal pentane and permit recycling, then isomerization efficiency improves, but utility utilization and capital requirements increase
Solution Approach 1:
The process replaces mechanical separation methods (sieves) with a thermal separation approach using the C5 splitter column. The column uses temperature gradients and phase equilibria to separate normal pentane from isomerized C5 hydrocarbons, eliminating the need for mechanical sieving equipment and associated utility requirements
Solution Approach 2:
The C5 splitter column exploits changes in physical parameters (boiling points, vapor pressures) of different C5 hydrocarbons to achieve separation. By controlling temperature and pressure parameters within the column, normal pentane is selectively removed while isomerized C5 components are recovered for recycling, achieving high isomerization efficiency with reduced utility consumption
3Object-generated harmful factors
If isomerization converts C6 and lighter hydrocarbons to improve octane, then octane number increases, but the equilibrium C5 isomerization ratio limits further improvement
Solution Approach 1:
The process implements a feedback loop where isomerized C5 hydrocarbons are separated by the C5 splitter, normal pentane is removed, and the enriched isomerized C5 stream is recycled back to the isomerization unit. This feedback mechanism continuously drives the isomerization reaction forward, overcoming the equilibrium limitation and achieving progressively higher octane numbers
Solution Approach 2:
The C5 splitter selectively discards normal pentane from the recycle stream while recovering isomerized C5 hydrocarbons (isopentane and other branched isomers). By discarding the unconverted normal pentane and recovering the valuable isomerized components, the process maintains high isomerization ratios and continues to improve octane without being constrained by equilibrium limitations
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 enables the efficient recycling of normal paraffinic C5 hydrocarbons while minimizing C4 hydrocarbon recycling, thereby improving isomerization efficiency and reducing capital and energy costs, enhancing the octane upgrading process.
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 column and recovering a stabilizer overhead stream, a bottom stream, and a side-stream
Implementation Method 3
passing at least a portion of the side-stream to a stripper column; sending a stripper bottom stream to a C5 splitter column
Implementation Method 4
C5 splitter column to obtain an overhead stream and a bottom stream; recycling the C5 splitter column bottom stream to the isomerization reaction zone
Data Source
AI summary
One exemplary embodiment can be a process for isomerizing a feed stream including one or more C4-C6 hydrocarbons. Generally, the process includes 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 side-stream; passing at least a portion of the side-stream to a stripper zone; and sending a stripper bottom stream to a C5 splitter zone and passing a stream from the C5 splitter zone to the isomerization reaction zone. Generally, the stabilizer overhead stream can include one or more C5− hydrocarbons, a bottom stream can include at least about 85%, by weight, one or more C6+ hydrocarbons, and a side-stream can include at least about 85%, by weight, one or more C5+ hydrocarbons. Also, the stripper bottom stream can include at least about 90%, by weight, one or more C5+ hydrocarbons.