High-Pressure CO2 Absorption Using Semi-Rich Solvent Flash Cooling
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Solution Overview
Problem
Current acid gas removal processes from high CO2 content gases are inefficient due to high capital and operating costs, significant solvent circulation, and refrigeration requirements, with existing methods failing to effectively address heat removal, solvent regeneration, and hydrocarbon losses.
Innovation Solution
A method involving a semi-rich solvent process where refrigeration and heating requirements are met within the treatment process by using pressure reduction and heat from the feed gas to cool and regenerate the solvent, reducing external refrigeration and heating needs, and employing a multi-stage flash vessel system to minimize hydrocarbon losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If physical solvent process is used for high CO2 removal, then CO2 absorption efficiency is improved, but refrigeration cooling duty and heating for regeneration increase significantly
Solution Approach 1:
The patent combines the refrigeration cooling function and heating function into a single heat exchanger unit. The rich solvent stream provides both cooling (to the feed gas) and heating (for solvent regeneration) functions simultaneously, eliminating the need for separate refrigeration and heating systems. This integration reduces equipment complexity and energy consumption while maintaining high CO2 absorption efficiency.
Solution Approach 2:
The rich solvent stream serves dual purposes: it cools the feed gas through heat exchange and provides heating for the lean solvent regeneration process. The system uses its own internal thermal energy (the temperature difference between rich and lean solvent streams) to satisfy both refrigeration and heating requirements, rather than relying on external utilities.
2Productivity
If chemical solvent is employed to react with acid gas, then acid gas removal efficiency is improved, but heat regeneration and large amounts of solvent recirculation are required
Solution Approach 1:
The patent transitions from chemical solvent absorption to physical solvent absorption, changing the fundamental mechanism from chemical reaction to physical dissolution. This parameter change eliminates the need for chemical reaction and heat regeneration, allowing for lower solvent circulation rates and reduced equipment complexity while maintaining effective acid gas removal.
3Adaptability or versatility
If membrane systems are used for CO2 separation, then adaptability to high CO2 content gases is improved, but methane losses increase significantly
Solution Approach 1:
The patent changes the separation mechanism from membrane permeation to physical solvent absorption. This parameter change allows for selective CO2 absorption based on solubility differences rather than permeability, significantly reducing methane losses while maintaining adaptability to high CO2 content feed gases.
4Quantity of substance
If physical solvent process is used, then CO2 loading increases with CO2 partial pressure, but significant heating for solvent regeneration is needed
Solution Approach 1:
The lean solvent stream is heated using thermal energy from the rich solvent stream through heat exchange. The system uses its own internal thermal energy to satisfy the heating requirement for solvent regeneration, eliminating or minimizing the need for external heating utilities.
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 consumption and capital costs, achieving at least 50% CO2 reduction in the feed gas with minimal hydrocarbon losses and reduced refrigeration needs, making the process more economically viable and environmentally friendly.
Implementation Method 1
The feed gas is cooled by the semi-rich solvent and the pressure-reduced rich solvent
Implementation Method 2
The two-phase mixture is flashed into the bottom section of an absorber
Implementation Method 3
the partially treated feed gas countercurrently contacts a lean solvent to so produce the semi-rich solvent
Implementation Method 4
refrigeration content that is generated by pressure reduction of the rich solvent
Implementation Method 5
the pressure-reduced rich solvent is heated by the feed gas and the semi-rich solvent to a temperature that is sufficient to flash a CO2 rich vapor
Data Source
AI summary
CO2 is removed from high-pressure feed gas in configurations and methods according to the inventive subject matter by contacting feed gas with cooled semi-rich solvent to form a two-phase mixture that is flashed into the bottom section of an absorber. Rich solvent from the absorber is then reduced in pressure to generate refrigeration for the semi-rich solvent and lean solvent countercurrently contacts the partially treated feed gas in the absorber to produce the semi-rich solvent. Among other advantages, cooling of the feed gas and semi-rich solvent by the pressure reduced rich solvent heats the rich solvent to allow enhanced regeneration of the solvent, and external refrigeration and heating of the solvent can be entirely avoided.