Inorganic Membrane CO2 Separation with Absorbent Optimization
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Solution Overview
Problem
The existing methods for separating carbon dioxide from natural gas using a combination of membrane separation and acid gas removal processes face challenges in minimizing methane permeation and energy consumption, particularly when the carbon dioxide concentration is low, leading to decreased production and increased energy usage.
Innovation Solution
A method that involves using an inorganic separation membrane to preferentially separate carbon dioxide from a mixed gas, followed by an acid gas removal process with an absorbent, where the carbon dioxide mole fraction at the outlet is optimized using an ideal separation factor ranging from 50 to 200, expressed by the formula XCO2=A·PR+B, to balance energy consumption and production loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If membrane separation is used to separate carbon dioxide from natural gas until carbon dioxide concentration becomes low, then carbon dioxide removal efficiency is improved, but methane permeation increases and production amount decreases
Solution Approach 1:
The patent divides the carbon dioxide separation process into two distinct stages: (1) membrane separation for high carbon dioxide concentration removal, and (2) acid gas removal process for low concentration carbon dioxide elimination. This segmentation allows each process to operate in its optimal efficiency range, preventing methane permeation losses in the second stage while maintaining high overall carbon dioxide removal efficiency.
2Use of energy by moving object
If membrane separation is used to separate carbon dioxide from natural gas, then energy consumption is reduced compared to acid gas removal process, but methane permeation occurs and production is decreased
Solution Approach 1:
The patent changes the operating parameters (carbon dioxide concentration range) for different separation processes. Membrane separation is applied when carbon dioxide concentration is high (energy-efficient), while acid gas removal is used when carbon dioxide concentration is low (minimizes methane loss). This parameter-based process selection optimizes both energy consumption and methane production.
3Loss of substance
If acid gas removal process is used for carbon dioxide separation, then methane permeation is minimized, but energy consumption increases
Solution Approach 1:
The patent applies acid gas removal process only partially - specifically when carbon dioxide concentration becomes low after membrane separation. This partial application avoids the high energy consumption of acid gas removal for the entire carbon dioxide removal task, while still achieving the benefit of minimized methane loss in the low-concentration region.
4Productivity
If combination of membrane separation and acid gas removal process is used, then proper distribution conditions can be achieved, but process complexity increases
Solution Approach 1:
The patent applies membrane separation as a preliminary action before acid gas removal. This preliminary removal of high-concentration carbon dioxide simplifies the subsequent acid gas removal process, making the overall combination process more manageable despite the increased number of units. The preliminary action prepares the gas stream for the second process, reducing its complexity.
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 allows for efficient separation of carbon dioxide while minimizing methane permeation and energy loss, achieving proper distribution conditions that reduce overall energy consumption in the acid gas removal process.
Implementation Method 1
separating carbon dioxide by a membrane separation using an inorganic separation membrane that is permeated by the carbon dioxide preferentially from the mixed gas
Implementation Method 2
carbon dioxide is separated by using an absorbent in a region having a low concentration of carbon dioxide
Data Source
AI summary
According to the present invention, in separating carbon dioxide by a membrane separation with a separation membrane system using an inorganic separation membrane from a mixed gas containing methane and carbon dioxide, and then by an acid gas removal process using an absorbent, by specifying the suitable range of the carbon dioxide mole fraction at the outlet on the carbon dioxide non-permeation side XCO2 in the membrane separation, which corresponds to an ideal separation factor of the inorganic separation membrane, the proper distribution conditions become feasible. As a result, a method for separating carbon dioxide in which the decrease of the production amount by methane permeation in the membrane separation and the energy loss accompanying the decrease are suppressed, and further the energy consumption in an acid gas removal process using an absorbent, which is a post-process, can be suppressed, is provided.