Fluidized Bed Boiler Wall Erosion Mitigation
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Solution Overview
Problem
In fluidized bed boilers, the interaction between the refractory and heat exchanger pipes leads to highly localized erosion due to the formation of vortices near the interface, which can cause malfunctions by creating small apertures or holes in the pipes.
Innovation Solution
The erosion of heat exchanger pipes can be reduced by eliminating the fins near the interface between the refractory and the heat exchanger pipes, allowing the bed material and gases to propagate deeper between the tubes, thereby reducing the formation of vortices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fins are continuously welded to heat exchanger pipes to form a gas-tight wall structure, then the wall structure is sealed and gas-tight, but highly localized erosion occurs near the refractory interface due to vortex formation
Solution Approach 1:
The patent removes the fins from the heat exchanger pipes in the specific region where they interface with the refractory. This extraction of the problematic element (fins) eliminates the vortex formation that causes localized erosion, while maintaining the gas-tight seal through alternative means such as gaskets or different sealing mechanisms in the refractory interface region.
Solution Approach 2:
The patent applies different structural characteristics to different regions of the heat exchanger pipes. The pipes have fins in some regions for gas-tight sealing and heat transfer, but the fins are removed or modified in the specific region where they contact the refractory to prevent vortex-induced erosion. This local differentiation allows each region to have the properties needed for its specific function.
2Reliability
If refractory is arranged on the inner side of the wall to protect heat exchanger pipes, then the pipes are protected from direct exposure to harsh conditions, but the refractory interferes with bed material flow and causes highly localized erosion at the interface
Solution Approach 1:
The patent removes the fins from the heat exchanger pipes in the region where they interface with the refractory. This extraction eliminates the vortex formation that causes localized erosion, while maintaining the gas-tight seal through alternative means such as gaskets or different sealing mechanisms in the refractory interface region.
Solution Approach 2:
The patent introduces a gap or clearance dimension between the refractory and the heat exchanger pipes, or between the refractory and the fin structure. This dimensional change allows bed material to flow around the refractory without forming vortices that cause erosion, while still maintaining the protective function of the refractory and the gas-tightness of the wall structure.
3Strength
If heat exchanger pipes are provided with a circumferentially extending metal coating to reduce erosion, then the pipes are more resistant to erosion, but the coating adds complexity to the pipe structure and manufacturing process
Solution Approach 1:
The patent removes the fins from the heat exchanger pipes in the specific region where they interface with the refractory. This extraction of the problematic element (fins) eliminates the vortex formation that causes localized erosion, while maintaining the gas-tight seal through alternative means such as gaskets or different sealing mechanisms in the refractory interface region.
Solution Approach 2:
The patent segments the heat exchanger pipe structure into different regions with different characteristics. The pipes have fins in some regions for gas-tight sealing and heat transfer, but the fins are removed or modified in the specific region where they contact the refractory to prevent vortex-induced erosion. This local differentiation allows each region to have the properties needed for its specific function.
Data Source
Figure 1a~1d
Figure 2a~2d
Figure 2e~3a
AI summary
A wall (200) for a fluidized bed boiler (300). The wall (200) comprises a first heat exchanger pipe (110) comprising a first primary portion (111) and a first secondary portion (112), and a second heat exchanger pipe (120) comprising a second primary portion (121) and a second secondary portion (122). A first gap (221) is arranged between the first secondary portion (112) and the second secondary portion (122), and at least a part of the first secondary portion (112) and at least a part of the second secondary portion (122) extend straight, in parallel, and within an imaginable plane (P). The wall (200) is configured such that particulate material is able to propagate through the first gap (221) from a first side (S1) of the plane (P) to the opposite second side (S2) of the plane (P). The wall (200) comprises a refractory (230) arranged on at least one side of a part of the first secondary portion (112) and a part of the second secondary portion (122). A fluidized bed boiler comprising the wall (200).