Carbonate Looping CO2 Capture in Gas Turbine Power Plants
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Solution Overview
Problem
The existing CO2 capture processes in gas turbine-based power plants are energy-intensive and costly due to low CO2 concentration and the need for solvent regeneration, particularly in combined cycle power plants, which reduces overall energy production and increases operational costs.
Innovation Solution
A carbonate looping system is implemented, comprising a first reactor for capturing CO2 by forming metal carbonate through carbonation and a second reactor for releasing CO2 through decarbonation at elevated temperatures, combined with a heat recovery steam generator and flue gas recirculation to enhance energy efficiency and reduce equipment size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If wet chemistry absorption is used to capture CO2 in a combined cycle power plant, then CO2 capture is achieved, but energy consumption increases and overall energy production is reduced
Solution Approach 1:
The patent replaces the chemical absorption process (wet chemistry) with a physical carbonation process using solid calcium oxide. The chemical reaction CaO + CO2 → CaCO3 occurs in a carbonation reactor, eliminating the need for liquid solvents and their associated regeneration energy requirements. This substitution fundamentally changes the energy profile of the capture process.
Solution Approach 2:
The patent changes the operational parameters from ambient temperature chemical absorption to elevated temperature (600-900°C) physical carbonation. This parameter change enables the use of waste heat from the power plant cycle to drive the carbonation reaction, turning an energy consumer into an energy-utilizing process that otherwise would be wasted.
2Quantity of substance
If CO2 capture is implemented in a conventional combined cycle power plant with low CO2 concentration (4%), then CO2 removal is achieved, but the cost and energy consumption per kg of captured CO2 increases
Solution Approach 1:
The patent converts the low CO2 concentration (4%) from a disadvantage into an advantage by using the large volume of flue gas as a source of continuous CO2 supply. The low concentration requires larger gas flow but enables simpler processing without the need for costly pre-concentration steps required by other methods. The abundant low-concentration CO2 stream is directly converted to solid carbonate.
Solution Approach 2:
The system uses its own waste heat to drive the carbonation process. The heat required for the endothermic decomposition of CaCO3 and for maintaining carbonation reactor temperature is supplied by the hot flue gas itself, creating a self-sustaining thermal cycle that eliminates external energy costs.
3Quantity of substance
If solvent regeneration is performed in conventional CO2 capture processes, then CO2 is released for storage, but time and energy are consumed reducing overall energy production
Solution Approach 1:
The patent divides the process into two separate reactors: a carbonation reactor where CaO captures CO2 to form CaCO3, and a calcination reactor where CaCO3 is decomposed to release pure CO2 and regenerate CaO. This segmentation allows continuous operation with independent optimization of each stage, eliminating the downtime associated with solvent regeneration in single-stage systems.
Solution Approach 2:
The system operates in periodic cycles between carbonation and calcination modes. During carbonation phase, CO2 is captured; during calcination phase, CO2 is released and the sorbent is regenerated. This periodic operation between the two reactors maintains continuous CO2 capture capability while enabling efficient periodic regeneration without interrupting overall process throughput.
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 reduces energy consumption and operating costs by increasing CO2 partial pressure, generating additional steam for power generation, and allowing for the reuse of oxygen, resulting in improved CO2 capture efficiency and reduced equipment requirements.
Implementation Method 1
a first reactor comprising solid material able to capture the CO2 present in the flue gas comprising CO2, such that metal carbonate is formed by carbonation
Implementation Method 2
a second reactor arranged to release CO2 by decarbonation of the carbonate at elevated temperature
Implementation Method 3
a heat recovery steam generator (HRSG) which may be arranged downstream the first reactor 20 to receive and recover heat therefrom
Data Source
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AI summary
The invention pertains a system for CO2 capturing in a gas turbine based power generation system 1 comprising a combined cycle power plant 2 and a carbonate looping unit 3 wherein the carbonate looping unit 3. Also a method for capturing CO2 in the gas turbine power generation system, comprising bringing the flue gas comprising CO2 into contact with solid material able to capture the CO2 present in the flue gas, such that metal carbonate is formed by carbonation; followed by release of the CO2 by decarbonation at elevated temperature