Oxyfuel Fluidized Bed Calcination for High-Purity CO2 Clinker Production
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Solution Overview
Problem
Existing methods for manufacturing cement clinker fail to achieve high purity carbon dioxide with minimal energy and device requirements, limiting the effectiveness of carbon capture technologies.
Innovation Solution
A method combining oxyfuel calcination in a circulating fluidized bed calciner with sintering in an ordinary kiln, maintaining overpressure and using recirculated exhaust gases to enhance carbon dioxide concentration, followed by purification in a carbon dioxide purification unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If oxyfuel calcination is used in a circulating fluidized bed reactor, then carbon dioxide purity is improved, but device complexity increases
Solution Approach 1:
The patent segments the cement manufacturing process into distinct functional units: a circulating fluidized bed reactor for calcination, a separator for solid-gas separation, and a purification unit for CO2 concentration. This segmentation allows each unit to be optimized for its specific function, achieving high CO2 purity while managing device complexity through modular design
Solution Approach 2:
The patent introduces an intermediary purification unit between the calcination reactor and the final CO2 output. This intermediary component (purification unit) mediates the transition from raw calcination flue gas to high-purity CO2, resolving the contradiction by adding a specialized component that handles the purity requirement without requiring complete redesign of the entire system
2Manufacturing precision
If oxygen concentration in the calciner is increased, then carbon dioxide purity is improved, but energy consumption increases
Solution Approach 1:
The patent optimizes the oxygen concentration parameter in the calciner to achieve the minimum required level for high CO2 purity without excessive energy consumption. By carefully controlling the oxygen concentration parameter and adjusting other operational parameters (temperature, residence time), the system achieves the desired CO2 purity while minimizing energy input
Solution Approach 2:
The patent implements feedback control where the CO2 purity output is monitored and used to adjust the oxygen concentration and other operational parameters. This feedback mechanism ensures that the system maintains high CO2 purity while automatically reducing energy consumption when optimal purity levels are achieved, preventing unnecessary energy expenditure
3Manufacturing precision
If recirculation of exhaust gas is implemented, then carbon dioxide concentration is improved, but device complexity increases
Solution Approach 1:
The patent merges the exhaust gas recirculation function with the existing circulating fluidized bed reactor design. The recirculation of CO2-rich exhaust gas is integrated into the fluidization process, where recirculated gas serves dual purposes: maintaining fluidization and concentrating CO2. This merging approach achieves high CO2 concentration without requiring completely separate recirculation equipment
Solution Approach 2:
The patent designs the circulating fluidized bed reactor to perform multiple functions simultaneously: calcination, gas-solid separation, and CO2 concentration through recirculation. The same reactor structure that enables calcination also serves as the CO2 concentration mechanism through controlled gas recirculation, achieving multi-functionality that reduces overall 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
Generates flue gas with >93% carbon dioxide purity, minimizing energy demand and impurities, and optimizing calcination efficiency while reducing plant modifications.
Implementation Method 1
precalcination of the preheated raw meal in a calciner being a circulating fluidized bed reactor with solids and gas recirculation by burning fuel with oxygen and recirculated gas instead of air
Implementation Method 2
maintained at an overpressure of at least some mbar
Implementation Method 3
capturing carbon dioxide from a calciner exhaust gas in a carbon dioxide purification unit
Implementation Method 4
transferring the precalcined raw meal to a rotary kiln for sintering to provide the cement clinker
Data Source
AI summary
A method for manufacturing cement clinker includes the steps: preheating a raw meal in a first preheater using kiln off-gas to provide a partially preheated raw meal, preheating the partially preheated raw meal in a second preheater to provide preheated raw meal, precalcination of the pre-heated raw meal in a calciner being a circulating fluidized bed reactor by burning fuel with oxygen and recirculated calciner exhaust gas instead of air to provide a precalcined raw meal wherein at least 2 mbar overpressure are adjusted in the calciner, transferring the precalcined raw meal to a rotary kiln for sintering to provide the cement clinker, cooling the cement clinker, and capturing carbon dioxide from a calciner exhaust gas in a carbon dioxide purification unit.