Apparatus and method for separating CO<sub>2 </sub>at low temperature comprising a step of separation by permeation
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Solution Overview
Problem
Membranes used for CO2 purification at low temperatures face challenges in proper temperature control during start-up and operation, leading to mechanical stresses and potential degradation, which affects efficiency and integrity.
Innovation Solution
A method involving a heat exchanger that separates the gas mixture into two portions, where one portion is heated to an intermediate temperature and the other is not heated, allowing controlled temperature regulation and gradual cooling of membranes during start-up, ensuring optimal operation and mechanical integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the gas mixture is directly cooled to low temperature for membrane operation, then CO2 purification efficiency is improved, but mechanical stresses and degradation of membranes occur due to rapid temperature change
Solution Approach 1:
The patent applies preliminary action by gradually cooling the membranes through a multi-stage process before full operation. The gas mixture is first cooled in a heat exchanger, then partially condensed, and only then is the permeate sent to the membrane unit. This gradual cooling approach prevents thermal shock and mechanical stress on the membranes while ensuring they are properly conditioned for efficient CO2 purification operation.
2Reliability
If the gas is heated before membrane separation, then membrane mechanical integrity is maintained, but CO2 purification efficiency decreases
Solution Approach 1:
The patent applies local quality by applying different temperature treatments to different portions of the gas stream. The retentate stream is cooled to low temperature to maximize CO2 purification efficiency, while the permeate stream undergoes a controlled temperature progression to protect membrane integrity. This localized temperature control allows each stream to be optimized for its specific function without compromising the other.
Solution Approach 2:
The patent implements dynamics by making the temperature control adaptive and progressive. The permeate undergoes a dynamic cooling process where temperature is gradually reduced through controlled condensation stages before reaching the membrane unit. This dynamic temperature adjustment allows the system to balance membrane protection with purification efficiency, adapting the thermal conditions to the operational stage and membrane tolerance.
3Loss of time
If rapid cooling is applied to start-up the membrane system, then operational time is reduced, but mechanical stresses increase causing potential degradation
Solution Approach 1:
The patent applies preliminary action by implementing a pre-cooling sequence for the permeate stream before it contacts the membranes. The gas is first cooled in a heat exchanger, then partially condensed to achieve intermediate temperatures, and only then is it sent to the membrane unit. This preliminary thermal conditioning reduces the temperature differential shock on the membranes during start-up, preventing mechanical stress and degradation while still enabling relatively quick system activation.
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 enables precise temperature control and gradual cooling of membranes, reducing mechanical stresses and maintaining optimal efficiency and integrity during start-up and normal operation, enhancing the overall CO2 purification process.
Implementation Method 1
A method involving a heat exchanger that separates the gas mixture into two portions, where one portion is heated to an intermediate temperature
Implementation Method 2
comprising a step of separation by permeation
Implementation Method 3
CO2 of human origin is essentially emitted into the atmosphere by the combustion of fossil fuels... based essentially on partial condensation of the CO2 at temperatures near its triple point
Data Source
AI summary
In a method for separating a mixture containing carbon dioxide, the mixture is cooled in a heat exchanger and partially condensed and a first liquid is separated from the mixture in a first system operating at low temperature comprising at least one first phase separator and a gas from the first system is treated in a membrane system to produce a permeate and a non-permeate, the gas from the first system being divided into two portions, a first portion being sent to the membrane system without being heated and a second portion being heated to at least an intermediate temperature of the heat exchanger and then sent to the membrane system without being cooled.