CO2 Absorber Level Control for Stable Solution Concentration

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Solution Overview

Problem

Conventional CO2 recovering apparatuses face challenges in maintaining a constant concentration of the CO2 absorbing solution, leading to reduced CO2 absorption performance when the gas supply amount changes, due to inadequate adjustment of water condensation and makeup water supply.

Innovation Solution

The CO2 recovering apparatus employs a level controller that adjusts the condensation amount of water in the exhaust gas and the supply of makeup water based on real-time measurements, using a combination of cooling tower adjustments and temperature control to maintain a stable liquid level and concentration of the CO2 absorbing solution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the gas supply amount of exhaust gas to the CO2 absorber is increased, then the CO2 absorption capacity is improved, but the accumulation amount of CO2 absorbing solution in the CO2 recovering unit increases, causing the liquid level to rise and the concentration of CO2 absorbing solution to decrease

Engineering Contradiction:
ImproveCO2 absorption capacityVSAvoidconcentration of CO2 absorbing solution
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The level controller continuously monitors the liquid level in the CO2 absorber and adjusts the makeup water supply amount based on real-time level measurements. When the liquid level rises due to increased gas supply, the controller automatically increases makeup water supply to maintain constant concentration, creating a closed-loop feedback control system that resolves the contradiction between productivity and composition stability.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts the makeup water supply parameter in response to changes in gas supply amount. By changing the water supply parameter based on liquid level feedback, the system maintains optimal CO2 absorbing solution concentration despite variations in operational demand, thereby resolving the contradiction between absorption capacity and solution concentration stability.

Inventive Principle:
Principle #35Parameter changes

2Stability of the object's composition

If the level controller increases the condensation amount of water or makeup water supply to maintain constant liquid level, then the liquid level stability is improved, but the concentration of CO2 absorbing solution is lowered, reducing CO2 absorption performance

Engineering Contradiction:
Improveliquid levelVSAvoidCO2 absorption performance
Core Design Contradiction:
Stability of the object's compositionVSProductivity

Solution Approach 1:

The level controller uses feedback from liquid level measurements to dynamically adjust makeup water supply. This ensures that water is added only when and where needed to maintain liquid level stability, preventing unnecessary dilution of the CO2 absorbing solution and preserving absorption performance.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

Instead of continuously adding makeup water to maintain constant liquid level, the system applies partial action by adjusting water supply only when liquid level deviations occur. This selective intervention maintains liquid level stability while minimizing dilution effects on CO2 absorbing solution concentration.

Inventive Principle:
Principle #16Partial or excessive action

3Stability of the object's composition

If the concentration of CO2 absorbing solution decreases due to excessive makeup water addition, then the liquid level stability is maintained, but the CO2 absorption performance is reduced

Engineering Contradiction:
Improveliquid level stabilityVSAvoidCO2 absorption performance
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The feedback control system monitors liquid level and adjusts makeup water supply accordingly, preventing excessive water addition that would dilute the CO2 absorbing solution. This ensures both liquid level stability and maintenance of sufficient CO2 absorption performance.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system automatically regulates its own water supply needs based on liquid level conditions, adding water only when the liquid level drops below the set point. This self-regulating mechanism prevents over-dilution while maintaining stable liquid levels, preserving the reliability of CO2 absorption performance.

Inventive Principle:
Principle #25Self-service

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 stabilizes the concentration of the CO2 absorbing solution, enhancing its absorption performance and efficiently utilizing steam in the regenerator, thereby improving the operational efficiency of the CO2 recovering process.

Implementation Method 1

the condensation amount of water contained in the exhaust gas within the CO2 absorber is adjusted

Methodology Applied
Scientific EffectCondensation: Condensation

Implementation Method 2

adjusting the cooling ratio of the exhaust gas by using a cooling tower

Methodology Applied
Scientific EffectCooling: Cooling

Implementation Method 3

a CO2 absorber that allows the exhaust gas to contact a CO2 absorbing solution and allows the CO2 absorbing solution to absorb CO2 contained in the exhaust gas

Methodology Applied
Scientific EffectAbsorption: Absorption (physical)

Implementation Method 4

a regenerator that releases CO2 absorbed by the CO2 absorbing solution and separates CO2 from the CO2 absorbing solution

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 5

causes the regenerator to heat the CO2 absorbing solution with vapor, thereby releasing the CO2 absorbed by the CO2 absorbing solution

Methodology Applied
Scientific EffectHeating: Heating

Data Source

PatentEP2974784B1Operation control method of co2 recovering apparatus
Publication Date: 2021.07.14 MITSUBISHI HEAVY IND ENG LTD
  • EP2974784B1 patent drawingFigure 1
  • EP2974784B1 patent drawingFigure 2
  • EP2974784B1 patent drawingFigure 3

AI summary

A CO2 recovering apparatus (10A) according to this embodiment includes a cooling tower (11); a CO2 absorber (12), a regenerator (13); an absorbing solution level meter (72) for measuring the amount of liquid at a tower bottom of the CO2 absorber (12); and a level controller (77) for performing automatic control or manual control for one or both of a supply amount of makeup water (76) and a condensation amount of water contained in an exhaust gas (15B) based on the liquid amount of at the bottom of the CO2 absorber (12) detected by the absorbing solution level meter (72).