Fluidized Bed CO2 Capture with Bauxite Limestone Particles

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Solution Overview

Problem

Current heat transfer systems in fluidized-bed boilers do not effectively decouple combustion, heat transfer, and environmental control processes, limiting the ability to optimize and reduce carbon dioxide emissions from fossil fuel combustion.

Innovation Solution

A recuperative and conductive heat transfer system that uses bauxite and limestone particles to absorb heat and capture carbon dioxide, with a vessel configuration allowing for the separation and recycling of particles, and a reheater to release captured CO2, achieving high purity and efficiency in CO2 removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional heat transfer systems are used in fluidized-bed boilers, then heat transfer function is provided, but combustion, heat transfer, and environmental control processes are coupled, limiting optimization capability

Engineering Contradiction:
Improveprocess optimization capabilityVSAvoidsystem coupling complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The system divides the combustion chamber into distinct functional zones: a combustion zone for fuel burning, a heat transfer zone with bauxite particles for heat absorption, and a CO2 capture zone with limestone particles for carbonation. This segmentation allows each zone to perform its specific function independently, decoupling combustion, heat transfer, and environmental control processes to enable separate optimization.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces bauxite and limestone particles as intermediary substances that mediate between combustion and heat transfer, and between heat transfer and CO2 capture. These particles serve as transfer media that enable heat and mass transfer without direct coupling of the combustion process with heat generation and emission control.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If CO2 capture is implemented using limestone particles, then carbon dioxide removal efficiency increases, but system energy consumption increases

Engineering Contradiction:
ImproveCO2 removal efficiencyVSAvoidsystem energy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system uses the heat generated during combustion to provide the thermal energy required for the CO2 capture process. The limestone particles are carbonated using heat from the combustion zone, eliminating the need for external energy input. The bauxite particles serve as heat transfer media that deliver combustion heat to the limestone particles, enabling self-sustaining CO2 capture without additional energy consumption.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent optimizes the particle size, concentration, and flow rates of bauxite and limestone particles to maximize CO2 capture efficiency. By controlling the fluidizing velocity, bed density, and residence time, the system achieves high CO2 removal efficiency while minimizing energy requirements for particle circulation and heat transfer.

Inventive Principle:
Principle #35Parameter changes

3Object-generated harmful factors

If bauxite and limestone particles are used for heat transfer and CO2 capture, then CO2 emissions reduction increases, but particle separation and recycling system complexity increases

Engineering Contradiction:
ImproveCO2 emissionsVSAvoidparticle separation and recycling system
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The system employs pneumatic transport and separation mechanisms to move and classify bauxite and limestone particles. Gas flow rates and particle density differences are utilized to separate captured CO2 from the particle stream, while pneumatic conveyance delivers particles to appropriate zones for heat transfer or CO2 capture, enabling efficient particle management without complex mechanical separation systems.

Inventive Principle:
Principle #29Pneumatics and hydraulics

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 system significantly reduces carbon dioxide emissions by capturing over 90% of CO2 from fossil fuel combustion gases, maintaining high efficiency and reducing operational costs through the use of natural forces and minimal energy input.

Implementation Method 1

second type solid particles capable of capturing carbon dioxide from the gasses

Methodology Applied
Scientific EffectAbsorption: Absorption (physical)

Implementation Method 2

first type solid particles capable of absorbing heat from the gasses

Methodology Applied
Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 3

the reheater directs the released carbon dioxide to a second reheater discharge

Methodology Applied
Scientific EffectThermal decomposition: Pyrolysis

Implementation Method 4

The vessel directs the received first type solid particles in a downwardly flow from the upper portion of the vessel to the lower portion of the vessel

Methodology Applied
Scientific EffectGravity: Gravitation

Implementation Method 5

as a gas is passed through a bed of solid particles, the flow of gas produces forces that tend to separate the particles from one another

Methodology Applied
Scientific EffectFluidization: Fluidisation

Data Source

PatentEP2250440B1Reducing carbon dioxide (CO2) emissions from the burning of a fossil fuel
Publication Date: 2015.04.15 ALSTOM TECH LTD
  • EP2250440B1 patent drawingFigure 1
  • EP2250440B1 patent drawingFigure 2
  • EP2250440B1 patent drawingFigure 3

AI summary

A system (10) for reducing carbon dioxide emissions from gasses generated in burning fossil fuel, includes a vessel (20), separator (38) and reheater (50). The upper portion (12) of the vessel (20) receives downward flowing, first type solid particles capable of absorbing heat from upward flowing gasses (22) and second type solid particles capable of capturing carbon dioxide from the gasses. The separator (38) separates the second type solid particles (26) with the captured carbon dioxide from the gasses discharged from the first vessel discharge, and directs the separated second type solid particles (26) with the captured carbon dioxide to a separator discharge. The reheater (28) directs the first type solid particles and the second type solid particles (24) with the captured carbon dioxide in a downwardly flow to a first reheater discharge, such that heat from the first type solid particles causes the captured carbon dioxide to be released from the second type solid particles (26).