Calcination Atmosphere Design for Direct CO2 Sequestration
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Solution Overview
Problem
Conventional calcination processes emit significant carbon dioxide and require costly and energy-intensive methods for carbon sequestration, and the use of high-grade fuels like natural gas increases operational costs.
Innovation Solution
A calcination process utilizing a mineral containing both a metal carbonate and fuel fraction, such as oil shale, is combusted in a mixture of oxygen, water vapor, and carbon dioxide to generate metal oxide, heat, and high-purity oxygen, allowing for direct carbon dioxide sequestration and recycling of heat for oxygen generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional calcination processes use natural gas combustion in air, then sufficient heat is generated to calcine limestone, but carbon dioxide emissions increase and flue gas requires energy-intensive separation for sequestration
Solution Approach 1:
The patent applies inert atmosphere principle by using a controlled gas mixture containing carbon dioxide and water vapour instead of air for combustion. This creates an inert-like environment that prevents nitrogen from participating in the combustion process, thereby eliminating nitrogen dilution in the flue gas and simplifying carbon dioxide separation for sequestration.
Solution Approach 2:
The patent changes the composition parameters of the combustion atmosphere by specifying a gas mixture with controlled levels of carbon dioxide (5-50% by volume) and water vapour (5-50% by volume). This parameter change transforms the combustion process to produce a concentrated carbon dioxide flue gas stream that requires minimal separation effort for sequestration.
2Ease of manufacture
If high-grade fuels like natural gas are used for calcination, then efficient combustion is achieved, but operational costs increase
Solution Approach 1:
The patent applies self-service principle by having the limestone itself serve as the fuel source through its carbonate content. The calcination reaction of calcium carbonate is endothermic and provides the necessary heat for the process, eliminating the need for external high-grade fuel inputs and reducing operational costs while maintaining combustion efficiency.
Solution Approach 2:
The patent makes the limestone serve multiple functions: it is both the raw material being processed and the fuel source providing heat for calcination. This multi-functionality reduces dependency on separate fuel supplies and lowers overall operational costs while maintaining process efficiency.
3Quantity of substance
If air is used as the combustion medium, then oxygen is readily available, but nitrogen dilutes the flue gas making carbon dioxide separation difficult
Solution Approach 1:
The patent replaces air with a controlled gas mixture that excludes nitrogen, creating an inert-like combustion environment. This eliminates the nitrogen dilution problem inherent in air-based combustion, producing a flue gas stream that is highly concentrated in carbon dioxide and requires minimal separation complexity for sequestration.
Solution Approach 2:
The patent changes the compositional parameters of the combustion medium by specifying a gas mixture with controlled levels of oxygen, carbon dioxide, and water vapour, while explicitly excluding nitrogen. This parameter change transforms the flue gas composition to simplify carbon dioxide separation and reduce device complexity.
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 process achieves carbon-neutral operation by utilizing low-grade fuels, reducing nitrogen dilution, and enables efficient separation and sequestration of carbon dioxide, while generating high-purity oxygen for industrial use.
Implementation Method 1
combusting the mineral in the presence of oxygen, water vapour and carbon dioxide, to generate a metal oxide, water vapour, carbon dioxide and heat
Implementation Method 2
the calcination of metal oxides is a major cause of greenhouse gas emissions... the natural gas reacts with the oxygen in the air, generating heat which is used to raise the temperature in the kiln to a sufficiently high temperature to cause the limestone to calcine
Data Source
AI summary
Described is the use of a mineral comprising a metal carbonate fraction and a fuel fraction, such as oil shale or coal shale, in a calcination process. The disclosed process can advantageously result in carbon dioxide being removed from the atmosphere. Further, in the process, heat energy generated during calcination can be used to separate oxygen from air, so that the oxygen can be fed back into the system. Alternatively or in addition, heat energy may also be used to compress the gaseous carbon dioxide generated from the calcination process.