Indirect Heat Calciner for Cement CO2 Capture
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Solution Overview
Problem
Portland cement production is a significant source of CO2 emissions, and existing carbon capture methods are either capital-intensive or energy-inefficient, requiring large additional processing plants and increased energy consumption.
Innovation Solution
A process that separates the CO2 from calcination and combustion processes using an indirect heat calciner reactor, producing a pure CO2 stream for capture, while reducing pressure drops and flue gas volume, and optimizing air flow to minimize energy consumption and emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If post-combustion capture using amine stripping is applied to capture CO2 from exhaust gas, then CO2 capture is achieved, but capital cost becomes very high
Solution Approach 1:
The invention extracts CO2 from the calcination process by using an indirect heating system where limestone is calcined in a separate chamber from the fuel combustion. This separation allows CO2 to be obtained as a concentrated stream from the calcination zone, eliminating the need for complex amine stripping systems required in conventional flue gas treatment.
Solution Approach 2:
The calcination process is segmented into separate functional zones: a combustion chamber for fuel burning and a separate calcination chamber for limestone decomposition. This segmentation enables independent optimization of each process, with the calcination chamber producing a CO2-rich atmosphere that can be directly captured without mixing with combustion flue gases.
2Object-generated harmful factors
If Calcium Looping process is used with lime as high temperature CO2 sorbent, then CO2 capture is achieved, but plant size and cost become very large
Solution Approach 1:
The invention makes the cement product itself serve the dual purpose of being both the final product and the CO2 capture medium. The high CO2 partial pressure in the indirect calcination chamber drives CO2 into the cement clinker during formation, eliminating the need for separate sorbent materials and large capture plant infrastructure.
3Use of energy by moving object
If conventional direct heating calcination is used, then energy efficiency is maintained, but CO2 capture becomes difficult
Solution Approach 1:
The heating and calcination functions are segmented into separate chambers. The combustion chamber maintains high thermal efficiency by directly burning fuel, while the separate indirect calcination chamber creates a CO2-rich environment suitable for capture. Heat is transferred indirectly through chamber walls, maintaining energy efficiency while enabling CO2 separation.
Solution Approach 2:
The chamber wall acts as an intermediary heat transfer medium between the combustion zone and the calcination zone. This indirect heating mechanism allows thermal energy to be transferred efficiently while maintaining separate gas atmospheres, enabling CO2 capture in the calcination chamber without mixing with combustion flue gases.
4Loss of energy
If flue gas is used for pre-heating particles in cyclone stack, then heat recuperation efficiency is improved, but pressure drop increases significantly
Solution Approach 1:
The invention extracts the pre-heating function from the flue gas stream and relocates it to a separate indirect heating zone. Particles are pre-heated by contact with heated chamber walls or heat exchange surfaces rather than by mixing with flue gas, eliminating the pressure drop penalties associated with flue gas injection while maintaining heat recuperation efficiency.
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 allows for a significant reduction in CO2 emissions, reduces the size and cost of capture plants, and minimizes energy consumption, achieving a 60% reduction in CO2 emissions from calcination processes without the need for large additional infrastructure.
Implementation Method 1
indirect heat generated from the combustion of a first fuel input to produce the preheated mixed powder
Implementation Method 2
calcining the preheated mixed powder in a calciner reactor to produce calcined mixed powder and a first gas stream of carbon dioxide
Implementation Method 3
introducing the calcined mixed powder into a kiln using direct heating
Data Source
AI summary
A method of manufacture of Portland cement clinker is described in a dry process that captures the carbon dioxide emitted from the calcination of carbonate minerals, principally limestone. The process uses an indirectly heated, counter-flow reactor to pre-heat and calcine the cement meal to produce a separate calcined meal and carbon dioxide gas stream, with external heat being provided by the combustion of a secondary fuel stream with pre-heated air. This calcined meal is injected into the conventional rotary kiln, where the hot flue gas from combustion of the primary fuel with pre-heated air is used to fuse, react and sinter the powders to form granules of cement clinker. The clinker and carbon dioxide streams are cooled by the air pre-heaters.