Light Naphtha Isomerization with Dual-Temperature Reactors
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Solution Overview
Problem
Existing isomerization processes for light naphtha face issues such as cracking of C7 paraffins to less valuable C1-C4 gases, benzene saturation leading to temperature rise, and undesired conversion of naphthenes to paraffins, resulting in lower octane numbers and catalyst degradation.
Innovation Solution
A two-reactor isomerization process using the same genre of catalyst, with one reactor operating at high temperature for paraffin conversion and the other at low temperature to minimize benzene saturation and maintain favorable equilibrium, reducing undesirable conversions and enhancing catalyst life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If isomerization process operates at high temperature to convert paraffins to isomers, then octane number increases, but C7 paraffins crack to C1-C4 gases and catalyst degrades
Solution Approach 1:
The isomerization process is divided into two separate reactors operating at different temperatures. The first reactor operates at high temperature (180-210°C) for paraffin conversion, while the second reactor operates at lower temperature (140-180°C) to minimize cracking. This segmentation allows each reactor to be optimized for its specific function, preventing excessive cracking while maintaining high octane production.
Solution Approach 2:
The process changes the temperature parameter across different reactor zones. By operating the first reactor at higher temperature and the second reactor at lower temperature, the system optimizes the balance between paraffin conversion rate and cracking minimization. This parameter variation allows simultaneous achievement of high octane number and reduced gas loss.
2Reliability
If benzene is saturated during isomerization to remove aromatics, then product purity improves, but temperature rises and conversion decreases
Solution Approach 1:
The saturation of benzene is performed in the second reactor at lower temperature, separate from the main paraffin conversion process in the first reactor. This segmentation allows benzene saturation to occur without causing excessive temperature rise that would inhibit paraffin conversion, achieving both high purity and high conversion simultaneously.
3Reliability
If naphthenes are converted to paraffins to increase octane, then octane number improves, but catalyst life decreases due to degradation
Solution Approach 1:
The process operates the second reactor at lower temperature (140-180°C) where naphthene conversion to paraffins occurs. This lower temperature operation minimizes catalyst degradation while still achieving the desired octane improvement from naphthene conversion, thereby extending catalyst life.
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
The process produces a high octane isomerate with increased liquid yield, reduced cracking, and improved octane number by converting low octane paraffins to branched paraffins while maintaining catalyst integrity.
Implementation Method 1
isomerization of light naphtha is one such process which is used to convert low octane light straight run naphtha into high octane gasoline blending stream. In this process, the octane number increases by conversion of the straight chain paraffinic and naphthenic hydrocarbons to their respective isomers
Implementation Method 2
Aromatics like benzene that are present in the light straight run naphtha, are also get saturated during this process
Data Source
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AI summary
The present invention is related to the isomerization process in which a light naphtha stream comprising of paraffinic (mono and single branched), naphthenic and aromatic hydrocarbons in the range of C5-C7 is contacted with the solid catalyst in multiple reaction zones and in presence of hydrogen to produce high octane gasoline predominantly comprising of paraffins (single and di-branched) and naphthenes. The process scheme comprises of more than one isomerization reaction section operating at different temperatures and other operating conditions. The catalyst employed in these reaction sections is a high coordination sulfated mixed metal oxide catalyst which contains at least one noble metal and sulfated zirconia in addition to the other components. The process of the present invention also comprises more than one fractionation section and recycling of a particular stream to the reaction zone for improving the isomerization of light naphtha.