CaO/CaCO3 Chemical Loop CO2 Capture Heat Exchange
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Solution Overview
Problem
Current Calcium looping systems for CO2 capture require high heat and oxygen consumption in the calciner, leading to increased energy costs and operational challenges, particularly due to the need for high-temperature calcination of carbonated solids, which can negatively impact sorbent activity and induce issues like ash softening and NOx emissions.
Innovation Solution
The system employs direct heat exchange methods using high-temperature flue gases to preheat both calcined and carbonated solids, reducing the energy requirements for calcination by bringing the solids to temperatures above the calcination temperature, thereby minimizing the need for pure oxygen and lowering overall energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high-temperature calcination is used to process carbonated solids, then calcination is achieved, but energy consumption increases and sorbent activity decreases
Solution Approach 1:
The patent applies preliminary action by preheating the carbonated solids to a temperature close to the calcination temperature (e.g., 800-850°C) before they enter the calciner. This is achieved through heat exchange with hot flue gases from the combustion chamber, so that when the solids enter the calciner, they require much less additional heating, thereby reducing energy consumption while maintaining effective calcination.
Solution Approach 2:
The patent uses hot flue gases as an intermediary heat transfer medium. These flue gases, which are already at high temperature from the combustion chamber, serve as a heat carrier to preheat the carbonated solids in a heat exchanger before the solids enter the calciner. This intermediary approach enables efficient heat transfer without requiring direct contact between the combustion products and the solids to be calcined.
2Temperature
If high-temperature calcination is used to process carbonated solids, then calcination is achieved, but harmful factors increase
Solution Approach 1:
By preheating the carbonated solids to near-calcination temperature before entering the calciner, the patent reduces the peak temperature exposure and duration of high-temperature processing. This preliminary heating action minimizes thermal stress on ash components, reducing ash softening, while also limiting the conditions that promote NOx formation, thus reducing harmful emissions.
3Productivity
If pure oxygen is used in the calciner, then calcination is efficient, but operational complexity increases
Solution Approach 1:
The patent applies self-service by using the hot flue gases from the combustion chamber itself as the heat source for preheating the carbonated solids. This internal heat recovery approach eliminates the need for external oxygen enrichment systems or additional fuel combustion systems, simplifying operations while maintaining calcination efficiency through the natural thermal energy already present in the flue gas stream.
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 significantly reduces the energy requirements in the calciner, decreases oxygen consumption, and simplifies the calciner design, making the CO2 capture process more economical and environmentally friendly by preheating solids to temperatures that facilitate efficient calcination without the need for high-temperature calcination.
Implementation Method 1
a first direct heat exchange from a high temperature flue gas to a recirculation stream of calcined solids from the calciner and a second direct heat exchange from a flue gas to the carbonated solids arriving to the calciner
Implementation Method 2
CaO particles are carbonated in contact with a flue gas at around 650°C to later release pure CO2 when supplied with sufficient heat for CaCO3 calcination
Implementation Method 3
release pure CO2 when supplied with sufficient heat for CaCO3 calcination at around 900°C
Data Source
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AI summary
This invention relates to a system for CO2 capture from a combustion flue gas using a CaO/CaCO3 chemical loop, wherein the CO2 is captured from large scale combustion systems using CaO as regenerable CO2 sorbent, where CaO particles are carbonated in contact with a flue gas at around 650°C to later release pure CO2 when supplied with sufficient heat for CaCO3 calcination at around 900°C, wherein the system of this invention is characterized by a first direct heat exchange from a high temperature flue gas to a recirculation stream of calcined solids from the calciner and/or a second direct heat exchange from a flue gas to the carbonated solids arriving to the calciner, thereby reducing the heat requirements for calcination.