Loopseal Heat Exchanger with Divided Particle Outlet
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Solution Overview
Problem
Loopseal heat exchangers in circulating fluidized bed boilers face issues with reverse air flow direction and ash agglomeration, leading to increased complexity, manufacturing costs, and reduced boiler capacity due to the need for additional chambers and larger channels to handle ash.
Innovation Solution
A loopseal heat exchanger design with a divided particle outlet using barrier elements and an ash removal channel, eliminating the need for a separate gas lock chamber, which controls air flow direction and separates ash from bed material, thereby simplifying the structure and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an additional chamber forming an extra loop seal is provided to prevent reverse air flow, then the air flow direction is controlled, but the structure of the heat exchanger becomes more complex and manufacturing cost increases
Solution Approach 1:
The particle outlet is divided into multiple outlets (first particle outlet and second particle outlet) separated by barrier elements. This segmentation prevents reverse air flow by creating distinct flow paths while avoiding the need for an additional chamber, thus maintaining structural simplicity.
Solution Approach 2:
Barrier elements are introduced as intermediary structures within the particle outlet to control air flow direction. These barrier elements act as mediators that prevent reverse flow without requiring a complete structural redesign or additional chambers.
2Ease of operation
If channels are designed sufficiently large to convey ash, then ash transport is enabled, but the capacity of the boiler is limited
Solution Approach 1:
The ash removal function is extracted from the main particle outlet by providing a separate ash removal channel. This allows the main channels to be optimized for particle flow while the ash channel handles ash transport, enabling better utilization of boiler capacity.
Solution Approach 2:
The outlet structure is segmented into particle outlets and ash removal channels with different size requirements. This segmentation allows each component to be optimized for its specific function, with ash removal channels being larger only where necessary while maintaining overall boiler capacity.
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 design prevents reverse air flow and effectively removes ash, enhancing boiler capacity and manufacturing efficiency by reducing the complexity and cost of the loopseal heat exchanger.
Implementation Method 1
a fluidized bed heat exchanger can be used in a loopseal of a circulating fluidized bed boiler. When the fluidized bed heat exchanger is arranged in connection with a steam generator to recover heat from the bed material of the fluidized bed, typically steam becomes superheated
Implementation Method 2
A circulating fluidized bed boiler comprises a furnace, a cyclone, and a loopseal. The fluidizing air of the furnace is designed to flow in a certain direction: from a furnace to a cyclone via the flue gas channel
Implementation Method 3
from the cyclone, the separated bed material continues to a loopseal
Data Source
AI summary
A circulating fluidized bed boiler, comprising a furnace, a loopseal, and a loopseal heat exchanger arranged in the loopseal. The loopseal heat exchanger comprises at least an inlet chamber, a bypass chamber, and a first heat exchange chamber, heat exchanger pipes arranged in the first heat exchange chamber, and a primary particle outlet for letting out bed material from the first heat exchange chamber. The primary particle outlet has at least a first part and a second part separated from each other by a barrier element in such a way that the first part of the primary particle outlet has a first height and a first width, wherein a ratio of the first height to the first width is less than 0.5 or more than 2. Use of the circulating fluidized bed boiler such that fluidizing gas and bed material are let out from the first heat exchange chamber via the primary particle outlet.