Polyamine Absorption for CO2 Removal in Claus Off-Gas
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Solution Overview
Problem
Current processes for removing hydrogen sulfide and carbon dioxide from 'sour gas' streams, particularly Claus off-gas, are inefficient due to the need for pressurization and require multiple equipment units, leading to high energy consumption and sensitivity to hydrogen sulfide presence.
Innovation Solution
A process that converts hydrogen sulfide to elemental sulfur in a Claus unit, followed by contacting the gas stream with an aqueous lean absorbing medium at reduced pressure, using specific polyamines that are less sensitive to hydrogen sulfide, allowing for effective CO2 removal with simplified equipment and reduced energy usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If Claus off-gas is treated with (activated) MDEA at elevated pressure to remove CO2, then effective CO2 removal is achieved, but multiple compressors and absorption units are required, increasing device complexity and energy consumption
Solution Approach 1:
The invention changes the pressure parameter from elevated pressure to near-atmospheric pressure (0.9-2 bara), eliminating the need for pressurization equipment. It also changes the chemical parameter by using specific polyamines with pKa<10.0 instead of MDEA, enabling effective CO2 removal without high pressure while reducing sensitivity to H2S presence
Solution Approach 2:
The invention extracts the CO2 removal function from the high-pressure MDEA process and implements it separately at near-atmospheric pressure using polyamines. This separates the CO2 removal step from the H2S removal step, allowing each to be optimized independently without requiring multiple compressors and absorption units
2Manufacturing precision
If Claus off-gas is pressurized before treatment with (activated) MDEA, then CO2 removal is effective, but energy consumption increases due to multiple compressors
Solution Approach 1:
The invention changes the pressure parameter from elevated pressure to near-atmospheric pressure (0.9-2 bara), eliminating the need for energy-consuming compressors. The polyamine-based process at low pressure achieves comparable or superior CO2 removal efficiency without the energy penalty of pressurization
3Manufacturing precision
If MDEA is used to treat Claus off-gas, then CO2 removal is effective, but the process becomes highly sensitive to H2S presence requiring H2S removal first
Solution Approach 1:
The invention converts the harmful effect of H2S presence into a beneficial situation by using polyamines that are inherently resistant to H2S degradation. The H2S that would normally degrade MDEA is now tolerated, and the polyamine's lower pKa ensures selective CO2 absorption even in the presence of H2S
Solution Approach 2:
The invention changes the chemical parameter by using polyamines with pKa<10.0 instead of MDEA. This parameter change makes the absorbing medium less sensitive to H2S presence while maintaining effective CO2 removal capability
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 process achieves effective CO2 removal with reduced equipment needs and energy consumption, while being less sensitive to hydrogen sulfide, enabling efficient treatment of large gas streams with a simplified setup.
Implementation Method 1
converting hydrogen sulfide in the feed gas stream to elemental sulfur in a Claus unit
Implementation Method 2
contacting at least a part of the gas stream obtained in step (i) with an aqueous lean absorbing medium in an absorption zone to absorb carbon dioxide
Data Source
AI summary
The invention relates to a process for removing hydrogen sulfide and carbon dioxide from a feed gas stream. H2S in the feed gas stream is converted to elemental sulfur in a Claus unit. At least a part of the gas stream obtained is contacted with an aqueous lean absorbing medium in an absorption zone at a pressure between 0.9 and 2 bara. The aqueous lean absorbing medium used comprises one or more amines chosen from: —a polyamine in the absence of tertiary amine functionalities having a pKa sufficient to neutralize carbamic acid, the polyamine having at least one primary amine functionality having a pKa smaller than 10.0 at 25° C., —a polyamine in the absence of tertiary amine functionalities having a pKa sufficient to neutralize carbamic acid, the polyamine having at least one secondary amine functionality having a pKa for each sorbing nitrogen smaller than 10.0 at 25° C. The process is improved as compared to a process involving Claus off-gas treatment with (activated) MDEA. Effective CO2 removal is achieved while at the same time a simplified line-up with less equipment can be used.