LPG C3 Removal for Higher-Efficiency Butane Isomerization
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Solution Overview
Problem
Conventional methods for producing MTBE from liquefied petroleum gas (LPG) have low reaction efficiency and high production costs due to the dilution of C4 hydrocarbons by inert C3 and lighter hydrocarbons, leading to increased energy consumption.
Innovation Solution
A method involving isomerization, separation, and dehydrogenation processes to separate and convert C3 and C4 hydrocarbons, increasing isobutane concentration and reducing inert components, thereby enhancing reaction efficiency and reducing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If liquefied petroleum gas is used as feedstock in isomerization and dehydrogenation units, then production cost is reduced, but reaction efficiency becomes low due to inert C3 hydrocarbons
Solution Approach 1:
The feedstock processing is divided into multiple stages: initial separation of C3 hydrocarbons from the LPG feedstock before isomerization, followed by isomerization of C4 components, then dehydrogenation. This segmentation removes inert components that reduce reaction efficiency while maintaining the economic advantage of using LPG as feedstock.
Solution Approach 2:
C3 hydrocarbons (propane) are extracted and removed from the LPG feedstock before entering the isomerization unit. This extraction eliminates the inert portion that dilutes the reactive C4 components, thereby improving reaction efficiency without increasing feedstock cost.
2Quantity of substance
If C3 hydrocarbons are present in the feed stream, then feedstock utilization is maximized, but reaction efficiency decreases due to inert portion
Solution Approach 1:
C3 hydrocarbons are extracted from the feed stream through a separation unit positioned before the isomerization unit. This removes the inert portion that reduces reaction efficiency while preserving the C4 components for high-value product production.
Solution Approach 2:
The separated C3 hydrocarbons are discarded from the MTBE production process stream, while the purified C4 stream is recovered and fed to the isomerization unit. This selective discarding and recovering improves reaction efficiency by eliminating inert dilution.
3Device complexity
If dehydrogenation is performed on mixed C4 stream, then process simplicity is maintained, but isobutene concentration in effluent is low
Solution Approach 1:
The process segments the C4 stream processing into: (1) isomerization of n-butane to isobutane in a dedicated isomerization unit, followed by (2) dehydrogenation of the enriched isobutane stream. This segmentation ensures high isobutene concentration in the dehydrogenation unit effluent while maintaining overall process simplicity through standardized unit operations.
Solution Approach 2:
Isomerization is performed as a preliminary action before dehydrogenation, converting n-butane to isobutane. This preliminary conversion ensures that the dehydrogenation unit receives a stream enriched in isobutane, which then converts to high concentrations of isobutene, improving the quality of the effluent stream.
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 method increases the reaction efficiency in the dehydrogenation and etherification units, leading to reduced production costs and higher yields of alkyl tert-butyl ether.
Implementation Method 1
processing a hydrocarbon mixture comprising propane, n-butane, and isobutane in an isomerization unit under reaction conditions sufficient to isomerize the n-butane to produce isobutane
Implementation Method 2
dehydrogenating the isobutane of the C4 stream in a dehydrogenation unit to produce isobutene in a dehydrogenation unit effluent
Implementation Method 3
reacting, in an etherification unit, the isobutene of the dehydrogenation unit effluent with an alkanol in the presence of an etherification catalyst under reaction conditions sufficient to produce alkyl tert-butyl ether
Data Source
AI summary
Systems and methods for processing a C3 and C4 hydrocarbon mixture have been disclosed. The C3 and C4 hydrocarbon mixture is first processed in an isomerization unit to isomerize n-butane to form isobutane. The resulting effluent stream from the isomerization unit comprising primarily isobutane and C3 hydrocarbons, collectively, is flowed into a separation unit configured to separate the effluent stream to form a C3 stream comprising C1 to C3 hydrocarbons and a C4 stream comprising primarily isobutane. The isobutane in the C4 stream is further dehydrogenated to form isobutene, which is further flowed into an MTBE synthesis unit as a feedstock for producing MTBE.