Multi-Stage Membrane Separation for High Acidic Gas Removal
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Solution Overview
Problem
Conventional methods for removing high amounts of acidic contaminants like carbon dioxide and hydrogen sulphide from natural gas streams are costly and inefficient, requiring large removal units and high operational costs.
Innovation Solution
A multistage membrane process that separates acidic contaminants from hydrocarbons, using membranes with higher permeance for acidic components than hydrocarbons, resulting in two pure streams: one for acidic contaminants and one for hydrocarbons, which can be recycled and further purified for use as pipeline gas or in enhanced oil recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional absorption methods are used to remove high amounts of acidic contaminants, then the contaminants can be removed from the natural gas stream, but the removal units become very large and require very high investment and operational costs
Solution Approach 1:
The separation process is divided into multiple stages with different membrane types. The first stage uses a membrane with high permeance for acidic contaminants to remove bulk amounts, while subsequent stages use membranes with different selectivity characteristics to achieve final purification. This segmentation allows each stage to be optimized for its specific function, avoiding the need for a single large-scale conventional absorption unit.
Solution Approach 2:
The invention changes the operating parameters by using membrane separation at specific pressure ranges (30-120 bara) and temperature conditions. The permeate is compressed back to feed pressure and recycled, creating a continuous separation process that operates efficiently at these optimized parameters, reducing the overall equipment size compared to conventional methods.
2Quantity of substance
If conventional absorption methods are used to remove high amounts of acidic contaminants, then the contaminants can be removed from the natural gas stream, but the operational costs become very high
Solution Approach 1:
The process uses the pressure differential naturally present in the system to drive membrane separation. The permeate is compressed back to feed pressure using a compressor, and this compressed stream is recycled to the feed. This self-service approach minimizes external energy inputs compared to continuous regeneration of absorption liquids required by conventional methods.
Solution Approach 2:
By operating at optimized pressure ranges (30-120 bara) and using membranes with high permeance, the process achieves efficient separation at lower energy consumption. The pressure-swing operation and membrane recycling create a thermodynamically efficient process that reduces operational costs.
3Productivity
If membranes with high permeance for acidic components are used, then acidic contaminants can be efficiently separated from hydrocarbons, but the selectivity between acidic contaminants and hydrocarbons must be maintained
Solution Approach 1:
The separation is performed in multiple stages using different membrane types. The first membrane stage is optimized for high permeance to remove bulk acidic contaminants, while subsequent stages use membranes with different selectivity characteristics to achieve the required purity. This segmentation allows each membrane to be optimized for its specific separation task without compromising overall purity requirements.
Solution Approach 2:
The permeate stream from the first stage acts as an intermediary that is compressed and recycled to the feed. This intermediary stream allows the system to maintain mass balance while achieving high separation efficiency and purity through the combined action of multiple membrane stages.
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 reduces operational costs and energy requirements, producing clean acidic contaminant streams for sulfur production or enhanced oil recovery and clean hydrocarbon streams suitable for pipeline use or LNG production, while maintaining high selectivity for acidic contaminants.
Implementation Method 1
contacting the hydrocarbonaceous feedstream with a membrane to obtain a hydrocarbon rich retentate and an acidic contaminants rich permeate
Data Source
AI summary
The invention concerns a process for the removal of gaseous acidic contaminants, especially carbon dioxide and/or hydrogen sulphide, in two or more stages from a gaseous hydrocarbonaceous feedstream (1) comprising hydrocarbons and said acidic contaminants, using one or more membranes in each separation stages. The gaseous hydrocarbonaceous feedstream is especially a natural gas stream. The process is especially suitable for feedstreams comprising very high amounts of acidic contaminants, especially carbon dioxide, e.g. more than 25 vol. %, or even more than 45 vol. %. In a first stage (2) a pure or almost pure stream of acidic contaminants is separated from the feedstream, the acidic contaminants (4) stream suitably containing less than 5 vol % of hydrocarbons. The remaining stream (3) comprises the hydrocarbons and still a certain amount of gaseous acidic contaminants. In a second stage (5) a pure or almost pure stream of hydrocarbons (8) is separated from the remaining stream, where after the then remaining stream (6) is combined with the feed for the first stage (1), the hydrocarbon stream suitably containing less than 5 vol % of acidic contaminants.