Regenerative Calcium Cycle Desulfurization via Segmented Reactors
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Solution Overview
Problem
Current regenerative calcium cycle (RCC) systems for capturing carbon dioxide from flue gas are energy demanding and inefficient, with the accumulation of heat-stable calcium sulfate (CaSO4) reducing adsorption capacity and requiring increased recirculation rates.
Innovation Solution
Implementing a dry desulfurization process at elevated temperatures (200 °C to 700 °C) before the carbonation reactor, using spent CaO from flue gas filters, and employing indirect heat exchange in the calcination reactor to reduce CaSO4 accumulation and enhance system efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If CaO adsorption of SO2 is performed concurrently with CO2 adsorption in the carbonation reactor, then efficient removal of SO2 is achieved, but CaSO4 accumulates in the RCC adsorbent circulation reducing adsorption capacity and requiring increased recirculation rate
Solution Approach 1:
The invention divides the desulfurization process from the carbonation process by introducing a separate desulfurization reactor. CaO is first used to remove SO2 in the desulfurization reactor, producing CaSO4. The remaining CaO then proceeds to the carbonation reactor for CO2 adsorption. This segmentation prevents CaSO4 accumulation in the carbonation reactor and maintains adsorption capacity while achieving efficient SO2 removal.
2Object-affected harmful factors
If recirculation rate is increased to compensate for reduced adsorption capacity, then SO2 removal is maintained, but energy consumption and system complexity increase
Solution Approach 1:
By segmenting the desulfurization and carbonation processes into separate reactors, the system maintains effective SO2 removal without needing to increase recirculation rate. The dedicated desulfurization reactor handles sulfur removal, allowing the carbonation reactor to operate with optimal CaO circulation for CO2 capture, thereby reducing overall energy consumption.
3Quantity of substance
If conventional CO2 capture methods are used, then CO2 separation is achieved, but energy demand and cost are high
Solution Approach 1:
The invention merges desulfurization and carbonation processes into an integrated system where both functions are achieved through coordinated operation of two reactors sharing the same CaO sorbent circulation. This combination allows simultaneous SO2 removal and CO2 capture with lower energy demand compared to conventional separate processes, as the system utilizes the heat from CO2 capture to support the endothermic desulfurization reactions.
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 drastically reduces the recirculation rate, decreases energy consumption, and lowers waste production while maintaining high CO2 capture efficiency and purity, thereby minimizing the overall impact on power plant efficiency.
Implementation Method 1
the carbon dioxide present in the flue gases is captured by carbonization in the hearth and then released by decarbonization
Implementation Method 2
The formed CaCO3 is subsequently regenerated by heating, whereby the so called calcination reaction produces carbon dioxide and CaO
Implementation Method 3
said heating is at least partially effected by indirect heat exchange with the hot flue gas stream from the combustion
Implementation Method 4
SO2 reacts with CaO to form CaSO4 (gypsum)
Data Source
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AI summary
The present invention relates to a method and system for combustion of a fuel and treatment of the resulting flue gas, said method comprising: combusting a fuel with air or oxygen to produce a hot flue gas stream containing at least carbon dioxide (CO2) and sulfur dioxide (SO2), bringing the flue gas stream into contact with solid calcium oxide (CaO) in a carbonation reactor (120) operating at a temperature at which CO2 in the flue gas reacts with CaO to form solid calcium carbonate (CaCO3), heating CaCO3 formed in the carbonation reactor in a calcination reactor (130) operating at a temperature at which CaCO3 is converted to CaO and CO2, whereby said heating is at least partially effected by indirect heat exchange with the hot flue gas stream from the combustion, and recirculating CaO formed in the calcination reactor back to the carbonation reactor, characterized in that the flue gas used for indirect heat exchange in the calcination reactor is subsequently subjected to dry desulfurization in a dry desulfurizer before it is brought into contact with CaO in the carbonation reactor.