Decarbonation Hydration Process for Limestone CO2 Recovery
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Solution Overview
Problem
Existing decarbonation processes for limestone and dolomite in kilns emit significant CO2 and lack efficient heat recovery, leading to high energy consumption and environmental impact.
Innovation Solution
A process and device for decarbonation and hydration of limestone, dolomite, or other carbonated materials, involving a first circuit for decarbonation and a second circuit for hydration, with selective separation means to manage gas and solid flows, allowing for CO2 sequestration and heat recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If traditional kilns are used for decarbonation, then CO2 is released from carbonated materials, but significant amounts of CO2 are emitted to the atmosphere and energy consumption is high
Solution Approach 1:
The patent converts the harmful CO2 emission into a beneficial product by capturing the CO2 released during decarbonation and making it available for utilization or sequestration. The CO2 that would otherwise be wasted is now a valuable output stream.
Solution Approach 2:
The patent recovers thermal energy from the decarbonation process by capturing heat from the hot CO2 gas and using it to preheat incoming carbonated materials or generate steam, thereby reducing the external energy input required for the decarbonation process.
2Object-generated harmful factors
If heat-regeneration measures are introduced in kilns, then CO2 footprint is reduced, but the generated CO2 is too diluted in flue gas to be used or sequestered efficiently
Solution Approach 1:
The patent segments the gas flow into separate streams: a CO2-rich stream from the decarbonation reactor and a separate flue gas stream. This segmentation allows the CO2 to be captured in high concentration without being diluted by the bulk flue gas, enabling efficient utilization or sequestration.
Solution Approach 2:
The patent extracts the CO2 from the flue gas stream by capturing it at the source (decarbonation reactor outlet) before it mixes with the flue gas. This extraction maintains high CO2 concentration in the captured stream while allowing the flue gas to be handled separately.
3Object-generated harmful factors
If calciner with close-loop circuit is used, then CO2 can be used or sequestered, but extended residence time in cooling zone causes recarbonation of the product
Solution Approach 1:
The patent segments the process into distinct functional zones: a decarbonation zone where CO2 is generated, a rapid cooling zone where temperature is quickly reduced below the carbonation equilibrium temperature, and a separation zone. This segmentation prevents recarbonation by quickly cooling the product away from the CO2-rich environment before carbonation can occur.
Solution Approach 2:
The patent employs rapid cooling to quickly bring the temperature of decarbonated particles below the carbonation equilibrium temperature, effectively skipping the temperature range where recarbonation would be favorable. This rapid temperature change prevents the thermodynamic driving force for recarbonation.
4Stability of the object's composition
If shaft kiln with pebbles is used, then decarbonation and cooling are separated, but complex locking mechanism is required for sealing and throughput is limited
Solution Approach 1:
The patent replaces complex mechanical locking mechanisms with alternative sealing approaches such as gasket-based seals, flange connections, or even friction-based sealing. This substitution maintains the necessary gas atmosphere separation while significantly reducing mechanical complexity and improving reliability.
Solution Approach 2:
The patent employs dynamic sealing solutions that can adapt to thermal expansion and contraction of components during operation. Flexible seals or adjustable mechanisms allow the system to maintain proper sealing under varying thermal conditions without requiring rigid, complex locking structures.
5Productivity
If flash calciner is used, then decarbonation is rapid, but no measure is provided to operate separated circuits for conveying particles with different gases
Solution Approach 1:
The patent segments the gas conveying system into separate circuits: one circuit uses CO2-rich gas to convey carbonated materials to the reactor, while another circuit uses inert or CO2-free gas to convey decarbonated products away from the reactor. This segmentation allows each gas to be optimized for its specific function without interference.
Solution Approach 2:
The patent introduces inert gases (such as nitrogen or carbon dioxide-free air) as intermediary carriers in the product conveyance circuit. These inert gases serve as mediators that transport the hot decarbonated particles away from the CO2-rich environment without causing recarbonation, while the CO2-rich gas continues to serve its purpose in the reactant conveyance circuit.
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 high production throughput of hydrated lime while producing a CO2-rich stream suitable for sequestration or use, and recovers heat generated by the hydration reaction, thereby reducing environmental impact and energy consumption.
Implementation Method 1
cooling the decarbonated particles in a cooling section of the second circuit, in which the decarbonated particles release a portion of their thermal energy, thereby heating the second gas
Implementation Method 2
hydrating the decarbonated particles in contact with water as liquid and/or steam... transferring at least a portion of the heat generated by the hydration of the decarbonated particles to the second gas
Data Source
AI summary
A process is disclosed for decarbonation of limestone, dolomite or other carbonated materials and hydration of decarbonated limestone, dolomite or other carbonated materials. The process may include: heating particles of carbonated materials in a reactor of a first circuit; conveying the particles of carbonated materials by a first entraining gas; transferring the decarbonated particles to a second circuit, in which a second gas circulates, the circuit including a hydration section; hydrating the decarbonated particles; and transferring at least a portion of the heat generated by the hydration of the decarbonated particles to the second gas being substantially free of carbon dioxide;. The first and second circuits are separated by first selective separation means allowing the passage of solids while substantially preventing the passage of the gases.