Carbonate Cycle CO2 Separation for Steam Generator Retrofitting
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Solution Overview
Problem
Existing CO2 separation methods from combustion gases, particularly those using carbonate cycles, are not suitable for retrofitting large steam generators and require high energy expenditure for oxygen provision, leading to inefficiencies and sorbent deactivation.
Innovation Solution
A carbonate cycle system utilizing CaO as a sorbent, where heat for desorption is generated in a desorber combustion chamber using fuel and air, with heat transfer via regenerators or heat pipes, allowing indirect heating and strict material separation to prevent sorbent deactivation, and enabling retrofitting and independent operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a carbonate cycle system is used for CO2 separation, then CO2 can be separated from exhaust gases, but the system is not suitable for retrofitting large steam generators
Solution Approach 1:
The system is divided into functionally independent modules: a desorber unit for sorbent regeneration, an absorber unit for CO2 capture, and a heat exchanger system. This modular segmentation allows the CO2 separation system to be retrofitted to existing steam generators without requiring complete system redesign, as each module can be independently installed and configured.
Solution Approach 2:
The desorber combustion chamber serves multiple functions: it provides heat for sorbent regeneration, generates steam through the steam generator integration, and can operate with various fuel types. This multi-functionality enables the system to be adapted to different existing steam generator configurations and fuel sources, enhancing retrofitting versatility.
2Productivity
If pure oxygen is used for calcination, then calcination efficiency is improved, but energy expenditure increases significantly
Solution Approach 1:
The desorber combustion chamber utilizes the sorbent itself (CaCO3) as the fuel source for calcination. The calcium carbonate decomposes endothermically to provide the necessary heat for the process, eliminating the need for external oxygen supply systems and reducing energy expenditure associated with oxygen provision while maintaining calcination efficiency.
Solution Approach 2:
The system exploits the phase transition and chemical decomposition of calcium carbonate at elevated temperatures. The endothermic decomposition reaction CaCO3 → CaO + CO2 absorbs heat and provides the thermal energy needed for the calcination process, creating a self-sustaining thermal cycle that reduces external energy requirements.
3Device complexity
If direct contact between ash components and sorbent is allowed, then the process is simpler, but sorbent deactivation occurs
Solution Approach 1:
The system extracts and separates the sorbent circulation loop from the combustion process. The desorber combustion chamber is designed to process ash and fuel separately from the sorbent, with dedicated gas separation and sorbent regeneration pathways. This extraction prevents harmful ash components from contacting the sorbent while maintaining process simplicity through clear functional separation.
Solution Approach 2:
The system introduces an intermediary gas phase separation mechanism between the combustion chamber and sorbent handling systems. Hot gases containing ash are separated from the sorbent circulation stream through heat exchangers and gas-sorbent separation devices, allowing heat transfer without direct material contact between ash and sorbent, thus protecting sorbent longevity.
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
The method achieves energy-efficient CO2 separation with prolonged sorbent longevity, reduced need for lime, and efficient heat utilization, maintaining power plant efficiency without CO2 compression, and can be retrofitted to existing systems without structural changes.
Implementation Method 1
CO2 is bound to CaO with the production of CaCO3 in the absorber (1)
Implementation Method 2
The heat required for this is generated in a desorber combustion chamber (7) and fed to the desorber (2) via a heat exchanger
Implementation Method 3
heat transfer via regenerators or heat pipes
Implementation Method 4
The CO2 is released in a desorber (2) at high temperature with the formation of CaO
Implementation Method 5
heat for desorption is generated in a desorber combustion chamber which is used to heat the desorber, using fuel and air as the oxidizing agent
Data Source
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AI summary
The method involves discharging the carbon dioxide containing exhaust gas flow from a combustion chamber in an absorber (1) of a sorbent-circuit-system, in which a sorbet is circulated in the circuit. The sorbent-circuit-system has the absorber and a desorber (2). The desorber is fed over a heat exchanger (3). An independent claim is also included for a device for deposition of carbon dioxide from the exhaust gas of a combustion chamber.