CO2 Absorbent Concentration Control for Steam Optimization

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Solution Overview

Problem

The concentration of CO2 absorbent decreases over time, leading to deteriorated CO2 recovery performance and fluctuations in steam consumption, making it challenging to maintain a constant volume of CO2 recovered and optimal steam usage in CO2 recovery processes.

Innovation Solution

A CO2 recovering method that involves detecting absorbent concentration and adjusting the volume of CO2 absorbent and steam supplied in the regenerator to maintain a constant CO2 recovery rate, using a controller to increase or decrease the circulation rate of the absorbent based on concentration changes and temperature variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the CO2 absorbent is circulated continuously in the absorber and regenerator, then the CO2 recovery process maintains operation, but the absorbent concentration decreases over time leading to deteriorated recovery performance

Engineering Contradiction:
ImproveCO2 recovery performanceVSAvoidabsorbent concentration
Core Design Contradiction:
ProductivityVSQuantity of substance

Solution Approach 1:

The patent implements a feedback control system where the absorbent concentration is continuously monitored and the circulation rate is automatically adjusted based on the measured concentration. When concentration decreases, the circulation rate is increased to maintain recovery performance, and vice versa. This closed-loop control resolves the contradiction by dynamically adapting the system operation to the actual absorbent state.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent transitions from a static circulation rate to a dynamic circulation rate that varies with absorbent concentration. The circulation rate is made adjustable and responsive to changing conditions, allowing the system to optimize performance at different operational stages. This dynamic adjustment resolves the contradiction between maintaining productivity and managing absorbent concentration depletion.

Inventive Principle:
Principle #15Dynamics

2Productivity

If the circulation rate of CO2 absorbent is increased to maintain recovery performance, then CO2 recovery volume is maintained, but steam consumption in the regenerator increases

Engineering Contradiction:
ImproveCO2 recovery volumeVSAvoidsteam consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The feedback control system monitors absorbent concentration and adjusts the circulation rate to the minimum necessary level to maintain target recovery performance. This prevents excessive circulation that would unnecessarily increase steam consumption in the regenerator, thus resolving the contradiction between maintaining productivity and minimizing energy use.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent dynamically changes the circulation rate parameter based on absorbent concentration measurements. By adjusting this key parameter, the system optimizes the balance between recovery volume and steam consumption, ensuring that the circulation rate is neither too high (wasting energy) nor too low (reducing performance).

Inventive Principle:
Principle #35Parameter changes

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 maintaining a constant volume of CO2 recovered per day at a predetermined level, minimizing steam consumption, and optimizing energy efficiency while ensuring stable CO2 recovery performance.

Implementation Method 1

The CO2 absorber brings the flue gas in a counter-current contact with the CO2 absorbent that is based on amine-based solvent, allowing the CO2 absorbent to absorb the CO2 contained in the flue gas by way of chemical reaction.

Methodology Applied
Scientific EffectChemical reaction: Chemical Bonding

Implementation Method 2

The regenerator causes CO2 absorbent that has absorbed CO2 to release CO2 to regenerate the CO2 absorbent.

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 3

a rich/lean solvent heat exchanger heats the rich solvent by way of the recovered CO2 absorbent that is lean solvent regenerated by the regenerator

Methodology Applied
Scientific EffectHeat exchanger: Heat Exchanger

Implementation Method 4

A regenerating heater then heats the lean solvent by way of steam, supplying steam inside the regenerator

Methodology Applied
Scientific EffectSteam heating: Heating

Implementation Method 5

A condenser then condenses steam contained in the CO2 gas

Methodology Applied
Scientific EffectCondensation: Condensation

Data Source

PatentEP2269713B1CO2 recovering method
Publication Date: 2017.05.24 MITSUBISHI HEAVY IND LTD
  • EP2269713B1 patent drawingFigure 1
  • EP2269713B1 patent drawingFigure 2~3
  • EP2269713B1 patent drawingFigure 4

AI summary

A CO2 recovering apparatus includes: a CO2 absorber (16) that brings flue gas containing CO2 into contact with CO2 absorbent to reduce the CO2 contained in the flue gas; a regenerator (18) that reduces CO2 contained in rich solvent that has absorbed CO2 in the CO2 absorber (16) to regenerate the rich solvent, so that the CO2 absorbent that is lean solvent having CO2 reduced in the regenerator (18) is reused in the CO2 absorber (16); and a controller that controls to detect the absorbent concentration in the CO2 absorbent, to increase the volume of CO2 absorbent to be circulated based on a decrease in the absorbent concentration, and to adjust the volume of steam to be supplied in the regenerator (18) based on the volume of the CO2 absorbent to be circulated.