Tail Gas CO2 Capture Using Amine Solvent Absorption
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Solution Overview
Problem
Current tail gas treating units in sulfur recovery processes vent significant amounts of carbon dioxide into the atmosphere, which is undesirable and contributes to greenhouse gas emissions, as they are not efficient in capturing and utilizing CO2 from the tail gas streams.
Innovation Solution
A gas processing facility and method that captures CO2 from the tail gas streams using a more reactive solvent in the tail gas treating unit, such as diethanol amine (DEA) or activated methyl diethanol amine (MDEA), which absorbs both hydrogen sulfide and carbon dioxide, allowing for their separation and subsequent injection into a subsurface reservoir for sequestration or enhanced oil recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional tail gas treating units are used to remove H2S from tail gas streams, then sulfur recovery efficiency is improved, but significant amounts of CO2 are vented into the atmosphere
Solution Approach 1:
The patent extracts CO2 from the tail gas stream using a selective absorber that preferentially absorbs CO2 over H2S. The CO2-rich solvent is then stripped to produce a concentrated CO2 stream for sequestration or utilization, while the regenerated solvent returns to the absorber for continued CO2 removal. This extraction process separates CO2 from the tail gas before sulfur recovery, eliminating CO2 emissions while maintaining H2S removal efficiency.
Solution Approach 2:
The patent segments the tail gas treatment process into distinct functional units: a CO2 removal section (absorber and stripper) and an H2S removal section (sulfur recovery unit). This segmentation allows independent optimization of each function - CO2 is removed first in the absorber/stripper system, then the treated gas undergoes H2S removal in the sulfur recovery unit. The segmentation enables CO2 to be captured and utilized separately from the sulfur recovery process.
2Object-generated harmful factors
If CO2 is captured and separated from tail gas streams, then CO2 emissions are reduced, but additional processing equipment and complexity are required
Solution Approach 1:
The patent merges the CO2 removal function with the existing tail gas treating infrastructure by integrating a CO2 absorber and stripper into the conventional H2S removal system. The CO2 absorber uses a amine-based solvent that can be regenerated in a stripper, and the resulting CO2-rich stream is fed to existing sulfur recovery or utilization equipment. This merging approach adds CO2 capture capability to conventional facilities without requiring completely separate systems.
Solution Approach 2:
The patent employs a multi-functional amine-based solvent system that can absorb both CO2 and H2S, but with different selectivities and absorption rates. The same solvent infrastructure (absorber, stripper, heat exchangers, pumps) serves dual purposes: removing CO2 from tail gas and preparing the gas stream for subsequent H2S removal. The regenerated solvent circulates continuously, providing universal service to both gas removal functions while reducing overall equipment complexity compared to separate dedicated systems.
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 CO2 emissions by capturing and utilizing CO2 from tail gas streams, enhancing sulfur recovery efficiency and providing a CO2-rich stream for injection into subsurface reservoirs, thereby reducing atmospheric venting and increasing the efficiency of sulfur recovery processes.
Implementation Method 1
the absorber vessel utilizes an amine that absorbs both carbon dioxide and sulfurous components such that a majority of the carbon dioxide entering the tail gas treating unit is absorbed in the absorber vessel
Implementation Method 2
a regenerator vessel for receiving the rich solvent stream, and separating the rich solvent stream into a regenerated solvent stream, and a sour gas stream
Data Source
AI summary
A gas processing facility and method for processing a hydrocarbon gas stream comprising sulfurous components and carbon dioxide. The gas processing facility includes an acid gas removal facility for separating the hydrocarbon gas stream into (i) a sweetened gas stream, and (ii) an acid gas stream comprised primarily of hydrogen sulfide and carbon dioxide. The gas processing facility also includes a Claus sulfur recovery unit that generates a tail gas, and a tail gas treating unit for receiving the tail gas. In various embodiments, the gas processing facility and method capture CO2 from the tail gas and injects it under pressure into a subsurface reservoir.