Ilmenite Particle Recovery in Fluidized Bed Boilers
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Solution Overview
Problem
Current bed management cycles in fluidized bed boilers face challenges in efficiently managing ilmenite particles, which deteriorate in oxygen-carrying capacity and attrition resistance due to repeated redox conditions, leading to increased resource consumption and operational costs.
Innovation Solution
Implementing a bed management cycle that separates and recirculates ilmenite particles based on their degree of activation, utilizing magnetic and electrostatic separation techniques to maintain their oxygen-carrying properties and mechanical strength, thereby reducing the need for fresh ilmenite and extending their residence time in the boiler.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If ilmenite particles are used as bed material in fluidized bed boiler, then oxygen-carrying capacity is improved, but attrition resistance deteriorates due to repeated redox conditions
Solution Approach 1:
The patent implements a separation system that discards worn ilmenite particles from the bed material and recycles fresh or less-worn particles. A separator (e.g., density-based separator or size-based separator) divides the bed material into different streams, allowing recovery of functional ilmenite particles while removing degraded ones, thus maintaining attrition resistance and oxygen-carrying capacity
Solution Approach 2:
The patent changes operational parameters such as fluidization velocity, temperature, or residence time to reduce the severity of redox cycling on ilmenite particles. By optimizing these parameters, the rate of attrition is reduced while maintaining sufficient oxygen-carrying capacity for combustion
2Use of energy by moving object
If ilmenite particles are continuously circulated in the boiler, then oxygen-carrying capacity is maintained, but mechanical strength deteriorates over time
Solution Approach 1:
The system continuously monitors and separates bed material particles, discarding those that have exceeded a certain circulation time or show signs of mechanical degradation. Fresh ilmenite particles are introduced to replace discarded ones, ensuring the bed material maintains both oxygen-carrying capacity and mechanical strength over extended operation
Solution Approach 2:
The patent implements a feedback mechanism where the state of ilmenite particles (mechanical strength, oxygen-carrying capacity) is continuously monitored. Based on this feedback, the system adjusts the rate of particle introduction, separation criteria, or operational conditions to maintain optimal performance while preventing excessive wear
3Use of energy by moving object
If fresh ilmenite is continuously added to compensate for losses, then oxygen-carrying capacity is maintained, but resource consumption increases
Solution Approach 1:
Instead of continuously adding fresh ilmenite, the system recovers and recycles particles that have not yet lost their functional properties. The separator identifies and recycles viable ilmenite particles back into the circulation loop, significantly reducing the need for fresh material input while maintaining oxygen-carrying capacity
Solution Approach 2:
The patent applies different treatment or separation criteria to different portions of the bed material based on their local condition (wear level, oxygen-carrying capacity). Rather than treating all particles uniformly, the system selectively recycles only those particles that still meet performance criteria, optimizing resource utilization
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 significantly reduces ilmenite consumption, enhances fuel flexibility, and prolongs the lifetime of boiler structures by maintaining the oxygen-carrying capacity and attrition resistance of ilmenite particles, making the combustion process more environmentally friendly and economical.
Implementation Method 1
separating the ilmenite particles by magnetic separation
Implementation Method 2
separating the ilmenite particles by magnetic separation and/or electric separation
Data Source
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AI summary
The invention relates to abed management cycle for a fluidized bed boiler, comprising the steps of: a) providing fresh ilmenite particles as bed material to the fluidized bed boiler; b) carrying out a fluidized bed combustion process; c) removing at least one ash stream comprising ilmenite particles from the fluidized bed boiler; d) separating ilmenite particles from the at least one ash stream; e) recirculating separated ilmenite particles into the bed of the fluidized bed boiler. The invention also relates to a corresponding arrangement for carrying out fluidized bed combustion, comprising a fluidized bed boiler comprising ilmenite particles as bed material; and a system for removing ash from the fluidized bed boiler; wherein the arrangement further comprises a separator for separating ilmenite particles from the re- moved ash; and means for recirculating separated ilmenite particles into the bed of the fluidized bed boiler.