Amine Absorption for CO2 Removal in Ethylene Oxide Cycles
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Solution Overview
Problem
Current processes for removing CO2 in ethylene oxide production are complex and costly, involving the use of glycol or mineral acid solutions that require complex regeneration and can damage catalysts, and existing methods do not effectively reduce amine traces to safe levels for the catalyst.
Innovation Solution
A process using an aqueous solution of amines, specifically N-methyldiethanolamine and piperazine, where the CO2-rich gas stream is further purified by intimate contact with pure water in a scrubbing column, avoiding the introduction of glycols or mineral acids, which reduces amine concentrations to non-damaging levels for the catalyst.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If glycol or mineral acid solutions are used for CO2 removal, then CO2 absorption capacity is improved, but process complexity and operational costs increase due to complex regeneration requirements
Solution Approach 1:
The patent employs a potash solution (KOH) as a single-use or easily replaceable absorbent medium. Rather than investing in complex regeneration systems for glycol or mineral acid solutions, the invention accepts that the potash solution will be consumed or degraded over time and can be simply replaced. This resolves the contradiction by sacrificing the durability aspect (using disposable absorbent) to achieve simplicity in the overall process design, eliminating the need for complex regeneration apparatus while maintaining effective CO2 removal capability.
2Quantity of substance
If glycol solutions are used for CO2 removal, then CO2 absorption is improved, but operational costs increase due to high temperature distillation requirements for amine removal
Solution Approach 1:
The patent changes the fundamental parameter of the absorbent medium from glycol-based or mineral acid-based solutions to a potash (KOH) solution. This parameter change fundamentally alters the regeneration requirements: instead of needing high-temperature distillation to remove dissolved amines from glycol solutions, the potash solution can be regenerated or replaced through simpler means. This resolves the contradiction by selecting an absorbent whose chemical properties allow for lower energy consumption during the regeneration or replacement cycle, thereby reducing operational costs while maintaining CO2 absorption effectiveness.
3Quantity of substance
If amine solutions are used for CO2 removal, then CO2 absorption is improved, but catalyst damage risk increases due to residual amine traces in the gas stream
Solution Approach 1:
The patent introduces a dual-stage absorption system where the potash solution serves as the primary CO2 absorbent, and water serves as an intermediary medium in a subsequent washing stage. The water washing stage acts as an intermediary step that removes any residual amine traces from the gas stream after CO2 absorption. This resolves the contradiction by adding an intermediate purification step that eliminates the harmful amine traces while preserving the beneficial CO2 absorption capability of the amine/potash solution.
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 simplifies the process, reduces operational costs, and effectively lowers amine concentrations in the gas stream to protect the catalyst, preventing damage and maintaining process efficiency.
Implementation Method 1
removing carbon dioxide (CO2) by means of an absorption medium from a cycle gas system, wherein the CO2 occurs within a process in which a chemical reaction is carried out in the gas phase in the presence of a catalyst, in which chemical reaction CO2 is generated as by product
Implementation Method 2
this cycle gas stream is brought into intimate contact with water to which no mineral acid and no higher glycol was added
Data Source
AI summary
A process for removing carbon dioxide (CO2) by means of an absorption medium from a cycle gas system, wherein the CO2 occurs within a process in which, in the gas phase, ethylene is oxidized by oxygen (O2) to ethylene oxide (EO) in the presence of a catalyst, in which, as by product, CO2 is generated, by using as absorption medium an aqueous solution of one or more amines, wherein, for further purification of the cycle gas stream obtained downstream of the CO2 absorption step, this cycle gas stream is brought into intimate contact with water to which no mineral acid and no higher glycol was added.