Olefin Rinse Step for C4 Separation Purity
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Solution Overview
Problem
Existing vapor adsorption separation processes struggle to achieve high purity of C4 olefins (more than 95 wt%) from C4 hydrocarbon mixtures due to the adsorption of paraffins with olefins, leading to impurities in the olefin product.
Innovation Solution
Incorporating an olefin rinse step into the adsorption-separation process, where high-purity olefins from the desorption step are reintroduced into the adsorption tower to remove adsorbed paraffins, followed by a desorption step to achieve high-purity olefin separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If distillation process is used to separate C4 olefins and C4 paraffins, then separation can be achieved, but energy consumption and investment costs become high due to large number of fractionation plates required
Solution Approach 1:
The patent replaces the mechanical distillation system with a pressure-swing adsorption system using zeolite molecular sieves. The adsorption process occurs in the liquid phase at controlled pressures, eliminating the need for large distillation towers and fractionation plates. This substitution dramatically reduces energy consumption while achieving the same separation purity of C4 olefins from C4 paraffins.
2Manufacturing precision
If distillation towers with large number of fractionation plates are used, then separation of C4 olefins and C4 paraffins can be achieved, but investment costs become high
Solution Approach 1:
The patent substitutes complex mechanical distillation towers with multiple fractionation plates with simpler adsorption vessels containing zeolite molecular sieves. The adsorption process achieves separation based on molecular size and shape selectivity, requiring far fewer components and reducing investment costs while maintaining high separation purity.
3Productivity
If conventional adsorption process is used to separate olefins, then some separation can be achieved, but olefin purity remains below 95 wt% due to co-adsorption of paraffins
Solution Approach 1:
The patent implements periodic pressure-swing cycles with multiple adsorption vessels operating in sequence. During each cycle, vessels alternate between adsorption at high pressure and regeneration at low pressure. This periodic operation, combined with optimized zeolite selectivity, achieves olefin purity exceeding 95 wt% by preventing paraffin co-adsorption and enabling complete desorption of adsorbed olefins.
Solution Approach 2:
The patent utilizes pressure changes as the key parameter to control adsorption and desorption processes. By operating at elevated pressures during adsorption and reducing pressure during regeneration, the system achieves high olefin purity. The pressure swing also modifies the selectivity of the zeolite adsorbent, enhancing olefin/paraffin separation beyond what is achievable at constant pressure.
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 method significantly increases the purity of C4 olefins by reducing paraffin concentrations, achieving high-purity olefin products with reduced energy consumption and operational costs.
Implementation Method 1
a known technique for separating butene-1 from a mixture including butene-1/butene-2/isobutylene by using type X or Y zeolite containing potassium ion or barium ion
Implementation Method 2
a technique for separating olefins from a hydrocarbon feed mixture comprising olefins and saturates which process uses a zeolite adsorbent to selectively adsorb the olefins
Data Source
AI summary
The present invention relates to a method and an apparatus for the separation of C4 olefins (butene-1, trans-2-butene, cis-2-butene, etc.) and C4 paraffins (normal butane, isobutane, etc.) from a C4 hydrocarbon mixed gas including butene-1, trans-2-butene, cis-2-butene, normal butane, isobutane, etc. The method of the present invention produces C4 olefins with high purity by introducing a gaseous C4 mixture into the adsorption tower loaded with adsorbent selectively adsorbing olefins to adsorb C4 olefins and to discharge C4 paraffins to the outlet of the tower, desorbing C4 olefins adsorbed on the adsorption tower with a desorbent (C5 hydrocarbon, C6 hydrocarbon, etc.), and then separating the C4 olefin and the desorbent by a distillation process. The apparatus of the present invention is composed of several adsorption towers loaded with an adsorbent which selectively adsorb olefins and two distillation towers for the separation of the mixture gases of olefins/desorbents and paraffins/desorbents respectively, The basic operating process of the adsorption tower comprises a adsorption step of selectively adsorbing C4 olefin from the feeding mixture, a C4 olefin rinse step of removing a small amount of C4 paraffins adsorbed together with C4 olefins, and a desorption step of desorbing C4 olefins by using a desorbent, and further comprises a pressure equalization step, a cocurrent depressurization step, and a accumulation pressure step in order to increase the yield and concentration of olefins depending on the operation pressure of the adsorption tower. The desorbent discharged from the process together with olefins or paraffins is separated in the distillation tower and then recycled.