Loopseal Heat Exchanger Ash Removal Channel
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Solution Overview
Problem
In circulating fluidized bed boilers, ash agglomerates in the loopseal heat exchanger can hinder air flow and limit boiler capacity, requiring larger pipelines and affecting furnace operation, as all ash is conveyed to the furnace, where it accumulates and forms agglomerates.
Innovation Solution
A loopseal heat exchanger with a first ash removal channel positioned lower than the particle outlet, utilizing gravity and fluidization to separate heavy ash from particulate material, allowing ash to be conveyed to a cooler instead of the furnace, thereby preventing agglomeration and improving heat recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If all bed material is conveyed from the loopseal heat exchanger to the furnace, then complete material circulation is achieved, but ash agglomerates form and hinder operation
Solution Approach 1:
The invention divides the single outlet into two separate outlets: a first particle outlet for conveying bed material to the furnace, and a first ash removal channel for removing ash to a cooler. This segmentation prevents ash from being conveyed to the furnace where it would form agglomerates, while maintaining bed material circulation.
Solution Approach 2:
The invention extracts ash from the bed material stream by providing a separate ash removal channel that selectively removes ash particles. This extraction prevents ash from entering the furnace circulation system, eliminating the harmful agglomeration effect while preserving the bed material circulation stability.
2Quantity of substance
If pipelines are designed larger to convey ash, then ash transport capacity is improved, but boiler capacity is limited
Solution Approach 1:
By extracting ash from the bed material stream through a separate removal channel, the invention eliminates the need to design pipelines with increased capacity to handle ash. The ash is removed before entering the circulation system, allowing standard-sized pipelines to handle the full bed material load, thereby maintaining boiler capacity.
Solution Approach 2:
The invention applies different handling approaches to different components: bed material is circulated through the furnace for combustion and heat generation, while ash is separately removed to a cooler for disposal or further processing. This local differentiation optimizes both ash management and boiler productivity.
3Stability of the object's composition
If ash is conveyed to the furnace, then complete material circulation is maintained, but air flow becomes uneven
Solution Approach 1:
The invention segments the material stream into bed material (conveyed to furnace) and ash (removed to cooler). This segmentation ensures that only combustible bed material enters the furnace, allowing uniform air distribution and combustion, while ash is separately handled, preventing air flow disruption.
Solution Approach 2:
By extracting ash from the circulation stream before it reaches the furnace, the invention eliminates the interference of non-combustible material with air flow patterns. The furnace receives only bed material that requires combustion, ensuring even air distribution and efficient operation.
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 solution effectively separates and removes ash from the loopseal heat exchanger, preventing agglomeration and improving air flow, reducing the need for larger pipelines, and allowing for more efficient heat recovery by directing ash to a cooler rather than the furnace.
Implementation Method 1
the first ash removal channel is arranged at a lower level than the first particle outlet. Thus, the heavy ash declines towards the first ash removal channel naturally by means of gravity
Implementation Method 2
the loopseal heat exchanger comprises nozzles for fluidizing the bed material within the loopseal heat exchanger. By fluidizing the bed material, the loopseal heat exchanger functions also as an air sieve to help separating the heavy ash from the particulate material
Implementation Method 3
A fluidized bed heat exchanger may be arranged in connection with a steam generator to recover heat from the bed material of the fluidized bed
Data Source
Figure 1
Figure 2a~2b
Figure 3~4
AI summary
The invention relates to a circulating fluidized bed boiler (1). The circulating fluidized bed boiler (1) comprises a furnace (50), a loopseal (5), and a loopseal heat exchanger (10) arranged in the loopseal (5). The loopseal heat exchanger (10) comprises walls (500, 505, 507, 510, 520, 530, 540, 550, 60) limiting an interior (11) of the loopseal heat exchanger (10), a first particle outlet (590) for letting out particulate material from the loopseal heat exchanger (10), an inlet (31) for receiving bed material, heat exchanger tubes (810, 820, 830) arranged in the interior (11) of the loopseal heat exchanger (10), and a first ash removal channel (211, 421) configured to let out ash from the loopseal heat exchanger (10). An ash cooler (600) is configured to receive ash from the first ash removal channel (211, 421). In the loopseal heat exchanger (1) the first ash removal channel (211, 421) is arranged at a lower level than the first particle outlet (590).