CO2 Absorbent Oxidation Inhibitor Control via Alkylamine Monitoring

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Solution Overview

Problem

The challenge is to control the concentration of oxidation inhibitors in CO2 absorbents without directly measuring their concentration, as existing methods face difficulties in dissolving and measuring organic sulfur compounds, leading to issues with oxidative degradation of alkanolamines in exhaust gas treatment systems.

Innovation Solution

A method and device that measure the concentration of alkylamine or the sum of alkylamine and ammonia in the exhaust gas to adjust the addition of oxidation inhibitors, such as mercaptoimidazoles and mercaptobenzimidazoles, in the CO2 absorbent, ensuring effective inhibition of oxidation without precise concentration measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If organic sulfur compounds are added as oxidation inhibitors to CO2 absorbent, then oxidative degradation of alkanolamines is inhibited, but the concentration of oxidation inhibitor is difficult to measure and control

Engineering Contradiction:
Improveoxidation inhibition effectivenessVSAvoidoxidation inhibitor concentration measurement
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent uses alkylamine concentration as an intermediary indicator to indirectly monitor and control oxidation inhibitor concentration. Instead of directly measuring the difficult-to-detect organic sulfur compound, the system measures alkylamine concentration in the exhaust gas, which correlates with oxidation inhibitor depletion, thereby solving the measurement problem

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent implements a feedback control system where alkylamine concentration measurements are continuously monitored and used to automatically adjust oxidation inhibitor addition rates. This closed-loop feedback enables precise control of inhibitor concentration despite measurement difficulties

Inventive Principle:
Principle #23Feedback

2Productivity

If alkanolamine solution is used as CO2 absorbent, then CO2 absorption is effective, but alkanolamine is oxidized and decomposed by oxygen and NOx in combustion exhaust gas

Engineering Contradiction:
ImproveCO2 absorption efficiencyVSAvoidalkanolamine solution stability
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The patent applies preliminary anti-action by adding oxidation inhibitors (organic sulfur compounds) to the CO2 absorbent before it contacts the exhaust gas. This preventive measure protects the alkanolamine from oxidation by oxygen and NOx in the combustion exhaust gas, maintaining solution stability while preserving CO2 absorption efficiency

Inventive Principle:
Principle #9Preliminary anti-action

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 allows for continuous monitoring and control of oxidation inhibitor levels, preventing oxidative degradation of alkanolamines and maintaining effective CO2 absorption efficiency in exhaust gas treatment systems.

Implementation Method 1

a CO2 absorption method using an alkanolamine solution

Methodology Applied
Scientific EffectChemical absorption: Absorption (physical)

Implementation Method 2

a desorber column that recovers CO2 by heating the amine solution that has absorbed CO2

Methodology Applied
Scientific EffectDesorption through heating: Desorption

Implementation Method 3

the alkanolamine in the absorbent is partially oxidized and decomposed by an oxidizing component such as O2 or NOx in a combustion exhaust gas

Methodology Applied
Scientific EffectOxidation inhibition: Oxidation

Data Source

PatentEP2612699B1Processing method and device for exhaust gas containing carbon dioxide
Publication Date: 2018.08.08 MITSUBISHI HITACHIPOWER SYST LTD
  • EP2612699B1 patent drawingFigure 1
  • EP2612699B1 patent drawingFigure 2
  • EP2612699B1 patent drawingFigure 3

AI summary

An object of the present invention is to provide a method for treating an exhaust gas containing CO2, that can adjust the concentration of an oxidation inhibitor in an absorbent to the concentration enough to inhibit oxidation, without measuring the concentration of the oxidation inhibitor in an alkanolamine contained in a CO2 absorbent. Disclosed are a method and a device for adjusting the compositional ratio of an absorbent, in which absorption and release of carbon dioxide are performed by adding an oxidation inhibitor to an alkanolamine absorbent when the sum of the concentrations of ammonia and an alkylamine in an absorber column outlet gas of a CO2 absorption equipment.