Dual Fluidized Bed Reactor Load Control via Hot Particle Transfer
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Solution Overview
Problem
Fluidized bed reactors face challenges in achieving rapid load changes and heat output control due to their large heat capacity, which limits their flexibility in responding to variable energy sources like solar and wind power.
Innovation Solution
A dual-fluidized bed reactor system where one reactor operates as a combustion reactor and the other as a pyrolyzer or gasifier, with controlled particle transfer and gas composition switching between modes to manage heat output and load changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the rate of feeding fuel and combustion air is varied to control load, then the heat output can be adjusted, but the large heat capacity of the fluidized bed reactor slows down the changes of burning rate and heat output
Solution Approach 1:
The single fluidized bed reactor is divided into two separate reactors: a combustion reactor for burning fuel and a pyrolyzing/gasifying reactor for processing solid fuel. This segmentation allows independent control of each reactor, enabling rapid load adjustments in the combustion reactor without being constrained by the large heat capacity of a single large bed.
Solution Approach 2:
Hot particles are used as an intermediary to transfer thermal energy from the combustion reactor to the pyrolyzing/gasifying reactor. By controlling the flow rate of hot particles, the system can rapidly adjust heat output without directly changing the combustion rate, thus overcoming the slow response caused by large heat capacity.
2Productivity
If the amount of bed particles in the furnace is changed to adjust heat absorption, then heat recovery rate can be varied, but the system complexity increases
Solution Approach 1:
The two reactors work together in a multi-functional system where the combustion reactor provides heat and the pyrolyzing/gasifying reactor processes solid fuel. This universal system can operate in multiple modes (combustion only, pyrolysis, gasification) and achieves heat recovery rate control through particle circulation rather than complex equipment modifications.
Solution Approach 2:
The system uses its own hot particles as the heat transfer medium, eliminating the need for external heat exchangers or complex control equipment. The hot particles circulating between reactors automatically regulate heat distribution based on their flow rate, simplifying the overall system while maintaining high heat recovery rates.
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
Enables rapid ramp-up and ramp-down of heat output, allowing the system to quickly adapt to grid power variations and maintain efficient operation.
Implementation Method 1
combusting a first portion of the solid fuel in the fluidized bed of particles with the oxygen containing gas so as to generate hot bed particles and a first stream of hot flue gas
Implementation Method 2
pyrolyzing or gasifying a portion of the second portion of the solid fuel in the second fluidized bed of particles so as to generate product gas
Implementation Method 3
gasifying a portion of the second portion of the solid fuel in the second fluidized bed of particles so as to generate product gas
Implementation Method 4
feeding fluidizing gas to the second fluidized bed reactor so as to form therein a second fluidized bed of particles
Data Source
AI summary
A reactor system and control method. The method includes feeding solid fuel and oxygen containing gas to a first fluidized bed reactor to form a fluidized bed of particles and combusting a first portion of the fuel in the bed with the oxygen containing gas to generate hot bed particles and a first stream of hot flue gas, conveying the first stream to the flue gas channel, transferring hot bed particles including a second portion of the solid fuel at a predetermined hot particles transfer rate from the first reactor to a second fluidized bed reactor, feeding fluidizing gas to the second reactor to form a second fluidized bed, and transferring bed particles from the second reactor to the first. The method includes first and second operation modes. In the first, the fluidizing gas is oxygen containing gas and, in the second, the gas includes steam, CO2, or inert gas.