Ejector Vortex Control for Circulating Fluidized Bed Solid Circulation
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Solution Overview
Problem
In circulating fluidized bed combustion/gasification systems, the stability of solid circulation is compromised due to pressure fluctuations affecting the loop seal, leading to reverse gas flow and inefficiencies, requiring frequent shutdowns and recharging of bed material, and existing systems rely on inefficient primary air supply to maintain the pressure barrier.
Innovation Solution
A method utilizing a vertically positioned ejector on the downcomer to create severe vortexes, controlling the flow-rate of solid particles by adjusting the pressurized gas flow, which generates a solid column to prevent counterflow and maintain stable solid circulation without relying on static or fluidized bed pressure barriers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a loop seal (fluidized bed pressure barrier) is used to maintain stable solid circulation, then the pressure barrier function is provided, but the system becomes unstable due to pressure fluctuations affecting the loop seal function
Solution Approach 1:
The invention extracts and eliminates the loop seal component from the system. Instead of using a fluidized bed loop seal that is susceptible to pressure fluctuations, the patent employs a cyclone separator with a direct downcomer connection, removing the problematic pressure barrier element while maintaining solid circulation stability.
Solution Approach 2:
The system segments the solid circulation path into distinct functional zones: the cyclone separation chamber and the downcomer return path. This segmentation allows each component to perform its specific function optimally without the need for a fluidized bed pressure barrier, enhancing overall system stability.
2Reliability
If primary air is supplied to the loop seal to maintain the pressure barrier, then the pressure barrier is sustained, but system efficiency decreases due to the additional air requirement and pressure loss
Solution Approach 1:
The invention removes the loop seal that requires primary air supply, thereby eliminating the associated air consumption and pressure loss. The direct-coupled cyclone-downcomer system maintains solid circulation without needing additional air for pressure barrier maintenance, improving overall system efficiency.
3Object-generated harmful factors
If the loop seal loses its function due to pressure fluctuations, then bed material escapes from the cyclone, but the system requires shutdown and restart to recharge bed material
Solution Approach 1:
By removing the loop seal entirely and implementing a direct downcomer connection from the cyclone, the invention eliminates the mechanism that causes bed material escape. The system maintains continuous stable operation without requiring shutdowns for recharging bed material.
Solution Approach 2:
The design inherently prevents the condition that leads to bed material escape by establishing a stable pressure distribution from the outset through the direct-coupled cyclone-downcomer configuration, avoiding the need for corrective shutdowns and restarts.
4Reliability
If a fluidized bed pressure barrier is used to prevent reverse gas flow, then gas flow control is achieved, but device complexity increases
Solution Approach 1:
The invention extracts and eliminates the complex fluidized bed pressure barrier structure. The reverse gas flow prevention function is achieved through the simpler direct downcomer connection from the cyclone separator, reducing device complexity while maintaining reliability.
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 enhances the efficiency of solid circulation, reduces agglomeration, and maintains a stable pressure barrier, allowing for continuous operation by controlling the flow-rate of solid particles and preventing reverse gas flow, thus improving the overall performance of the system.
Implementation Method 1
A method utilizing a vertically positioned ejector on the downcomer to create severe vortexes, controlling the flow-rate of solid particles
Implementation Method 2
creates a solid column (b) between the reactor (2) and the cyclone (3) to prevent counter flow of particle and gas
Implementation Method 3
at least one cyclone (3) which is in connection with the reactor (2) in order that solid particles such as coal/biomass are separated from gas flow
Data Source
Figure 1
Figure 2
AI summary
The present invention is related to a circulating fluidized bed gasification or combustion system (1) using coal or biomass as raw material and comprising a combustion/gasification reactor (2); a cyclone (3) which is in connection with the reactor (2) in order that solid particles are separated from gas flow; a downcomer (4) which is in connection with the reactor (2) and the cyclone (3), extends along the reactor (2), and enables solid particles captured by the cyclone (3) to be sent to the combustion/gasification reactor (2) again; a distributing plate (5) which is in connection with the reactor (2) and performs primary gas supply to the system (1) homogeneously; at least one conduit which is positioned parallel to the downcomer (4); an ejector (7) which is positioned on the downcomer (4) vertically, comprises at least one nozzle (6) spraying pressurized gas towards the reactor (2), and creates a solid column (b) between the reactor (2) and the cyclone (3) by creating vortexes (a) on account of the fact that the pressurized gas sprayed by means of the said nozzle (6) spreads to the environment from the nozzle located on the downcomer (4) in order to prevent counter flow of particle and gas that may occur towards the downcomer (4) and the cyclone (3) from inside the reactor (2).