Sweep Membrane CO2 Capture Between Compression Stages
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Solution Overview
Problem
Current membrane-based CO2 capture technologies for gas-fired power plants are limited by the high temperature of the compressed gas streams, which requires expensive inorganic membranes and significant cooling, making the process costly and energy-intensive.
Innovation Solution
Integrating a sweep-based membrane gas separation step between compression stages, allowing for carbon dioxide capture at intermediate pressures (2-10 bar) and temperatures (100-200°C), enabling the use of lower-cost polymeric membranes and reducing the need for extensive cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If membrane-based CO2 capture is applied to hot compressed gas streams, then CO2 separation can be achieved, but expensive inorganic membranes and significant cooling are required
Solution Approach 1:
The patent applies preliminary cooling of the compressed gas stream before it enters the membrane separation unit. By cooling the gas to a temperature suitable for polymeric membranes (below 100°C) before separation, the system can use lower-cost polymeric membranes instead of expensive inorganic membranes that would be required for hot gas streams. This preliminary temperature adjustment resolves the contradiction between separation effectiveness and manufacturing cost.
2Quantity of substance
If compression is performed before membrane separation, then CO2 enrichment is achieved, but the compressed gas temperature becomes too high for conventional membranes
Solution Approach 1:
The patent extracts the temperature problem from the compression-separation process by introducing an independent cooling step between compression and membrane separation. The compression step increases CO2 concentration as desired, while the subsequent cooling step removes the excessive heat generated during compression. This separation of functions allows the system to achieve both CO2 enrichment and suitable temperature for polymeric membranes without using expensive inorganic materials.
3Temperature
If extensive cooling is applied to compressed gas, then membrane operation temperature is achieved, but energy consumption increases
Solution Approach 1:
The patent merges the cooling function with the existing process by using the cooling step to prepare the compressed gas for membrane separation. Rather than treating cooling as a separate energy-intensive operation, it is integrated into the overall compression-separation-process flow. The cooling is performed to the minimum necessary temperature for polymeric membrane operation, optimizing energy usage while achieving the required temperature condition for cost-effective membrane selection.
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 approach significantly reduces energy and cost requirements for CO2 capture, achieving high CO2 enrichment and concentration while minimizing heat loss, thus enhancing the economic viability of CO2 separation from gas-fired power plant emissions.
Implementation Method 1
a membrane separation step... using membranes that are selective in favor of carbon dioxide over oxygen and nitrogen
Implementation Method 2
a sweep gas stream, 428, comprising air, oxygen-enriched air or oxygen flows across the permeate side. The membrane separation step divides stream 425 into residue stream 429, depleted in carbon dioxide
Data Source
AI summary
Sweep-based gas separation processes for reducing carbon dioxide emissions from gas-fired power plants. The invention involves at least two compression steps, a combustion step, a carbon dioxide capture step, a power generate step, and a sweep-based membrane separation step. One of the compression steps is used to produce a low-pressure, low-temperature compressed stream that is sent for treatment in the carbon dioxide capture step, thereby avoiding the need to expend large amounts of energy to cool an otherwise hot compressed stream from a typical compressor that produces a high-pressure stream, usually at 20-30 bar or more.