Method and device for washing and purification with low-temperature methanol
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Solution Overview
Problem
The existing low-temperature methanol gas washing process requires a large amount of methanol and high cooling capacity to handle high CO2 content in raw shift gas, leading to significant energy consumption and investment costs.
Innovation Solution
The method combines CO2 condensation and an expander to reduce the cooling capacity load by condensing CO2 from raw shift gas, decompressing it, and using the expander to produce low-pressure, low-temperature CO2 gas, which reduces the amount of methanol needed and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a large amount of methanol is used to wash high CO2 content gas, then the purification effectiveness is improved, but the energy consumption and cooling capacity load increase significantly
Solution Approach 1:
The patent extracts CO2 from the raw shift gas through condensation before the methanol washing process. By removing a portion of CO2 (30-70% according to embodiments) through physical condensation at low temperatures, the subsequent methanol washing process deals with reduced CO2 content, thereby reducing methanol circulation requirements and energy consumption while maintaining purification effectiveness
Solution Approach 2:
The patent changes the temperature parameter to condense CO2 from the raw shift gas. By cooling the gas to low temperatures (below CO2 condensation point), CO2 transforms from gas to liquid phase, separating it from the main gas stream. This parameter change enables pre-concentration of CO2 removal, reducing the burden on the methanol washing system
2Productivity
If a large amount of methanol is circulated to wash CO2, then the CO2 removal capacity is improved, but the cooling capacity load and investment costs increase
Solution Approach 1:
The patent extracts CO2 through condensation before methanol washing, reducing the CO2 load that requires methanol circulation. This extraction approach decreases the required methanol circulation rate and相应 reduces the cooling capacity needed for methanol regeneration, while maintaining overall CO2 removal capacity through the combined process
3Manufacturing precision
If high cooling capacity is used to handle high CO2 content, then the gas washing effectiveness is improved, but the investment costs increase
Solution Approach 1:
The patent segments the CO2 removal process into two distinct stages: (1) physical condensation and separation of CO2 at low temperatures, and (2) methanol washing of the remaining gas. This segmentation allows each stage to be optimized independently, reducing the overall equipment size and investment costs while maintaining washing effectiveness
Solution Approach 2:
By extracting CO2 through condensation before the methanol washing stage, the patent reduces the required capacity of the methanol washing system. This extraction approach decreases the size of scrubbers, heat exchangers, and other equipment, thereby reducing investment costs while preserving gas washing effectiveness
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 reduces the cooling capacity load by 60%, decreases energy consumption, and lowers investment costs by minimizing the circulation of lean methanol and reducing scrubber diameter.
Implementation Method 1
vaporizing the CO2-containing liquid and reducing the pressure by expansion to obtain a CO2-containing gas
Implementation Method 2
performing a heat exchange and heating to the medium-pressure CO2-containing gas
Implementation Method 3
condensing a raw shift gas and conducting a gas-liquid separation to obtain CO2-containing liquid
Data Source
AI summary
A method for washing and purification with a low-temperature methanol at least includes the following steps: condensing a raw shift gas and conducting a gas-liquid separation to obtain CO2-containing liquid and a separated raw material gas; and vaporizing the CO2-containing liquid and reducing a pressure by an expansion to obtain a CO2-containing gas; and washing the separated raw material gas with a methanol to obtain a purified gas. The present application combines CO2 condensation and an expander, so that the load of cooling capacity of the system for washing with a low-temperature methanol is reduced by 60%. At the same time, the external work done by the expander reduces the energy consumption of the system. After the CO2 in the purifying gas of desulfurization in the section A of the scrubber is condensed, the amount of CO2 entering the section B is reduced.