Outward-Bent Waterwall Corner Fin for Fluidized Bed Erosion
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Solution Overview
Problem
Conventional fluidized bed reactor tubular waterwalls experience severe erosion in lower corner regions due to vigorously moving bed particles, especially when operating outside designed parameters, leading to refractory lining damage and overheating of fins.
Innovation Solution
A tubular waterwall structure with a corner fin design where the lower portion of one wall is shifted outwards and refractory-lined, and the adjacent wall has a bare lower portion, with a wider planar lower beveled corner fin and a narrower upper beveled corner fin to prevent erosion and overheating, and a refractory lining that extends only to the vertical plane of the upper portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lower portion of tubular waterwalls is protected by refractory lining, then erosion resistance is improved, but particle bouncing from the refractory ledge causes erosion of the vertical watertube panel above
Solution Approach 1:
Instead of making the refractory surface flush or recessed to minimize particle bouncing, the invention inverts the approach by bending the tubular waterwall outwards so that the refractory surface is exposed and protrudes from the vertical tubewall. This changes the interaction geometry between particles and refractory surface, allowing particles to slide down the curved surface rather than bounce off a flat ledge.
Solution Approach 2:
The invention applies curvature by bending the tubular waterwall into an outwards curved configuration. This curvature creates a smooth transition surface for the refractory lining, enabling particles to follow the curved path down the wall rather than bouncing off sharp edges, thereby reducing erosion of the vertical tubewall section above.
2Object-affected harmful factors
If the tubular waterwall is bent outwards to expose refractory surface, then particle bouncing is reduced, but the corner structure becomes complex when joining horizontally adjacent wall portions
Solution Approach 1:
The invention applies asymmetry in the corner structure by providing different configurations for different wall portions: one wall portion is bent outwards with exposed refractory surface, while the adjacent wall portion remains vertical with recessed refractory surface. The corner fin is designed with asymmetric width (wider at bottom, narrower at top) to accommodate this asymmetric configuration and facilitate proper joining.
Solution Approach 2:
The invention applies local quality by making each wall portion have different geometric characteristics suited to its specific function and location. The outwards bent portion has exposed refractory for erosion protection, while the vertical portion has recessed refractory. The corner fin has varying width along its height to locally adapt to the joining requirements between these different wall configurations.
3Use of energy by moving object
If high pressure water flows inside tubes to extract heat, then heat transfer efficiency is improved, but the fins connecting tubes are susceptible to overheating in high temperature zones
Solution Approach 1:
The invention introduces refractory material as an intermediary between the high-temperature external environment and the metal fins. The refractory lining acts as a thermal barrier that protects the fins from direct exposure to high temperatures while allowing the water inside tubes to continue extracting heat efficiently, thus preventing fin overheating while maintaining heat transfer performance.
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 effectively minimizes erosion and overheating by providing a durable refractory lining and thermal insulation, reducing erosive eddies and maintaining efficient heat transfer in the reactor.
Implementation Method 1
the tubular waterwalls, especially the lower portions of the tubular waterwalls, have a risk of erosion, especially if the reactor is operated outside traditional or designed operating parameters
Implementation Method 2
High pressure water flows inside the tubes to extract heat from high temperature particles and gases in the reactor
Implementation Method 3
the lower portions of the tubular waterwalls are conventionally protected by a layer of refractory
Implementation Method 4
Due to vigorously moving bed particles, the tubular waterwalls, especially the lower portions of the tubular waterwalls, have a risk of erosion
Data Source
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AI summary
A tubular waterwall structure in a fluidized bed reaction chamber, and a fluidized bed reaction chamber with such a tubular waterwall structure, the tubular waterwalls comprising horizontally adjacent first and second wall portions forming a corner structure and being constituted by vertical tubes and fins centrally attached to the tubes and having a first width, wherein the first wall portion has an outermost tube next to the corner, an upper portion defining an upper vertical plane in an upper level range and a lower portion defining a lower vertical plane in a lower level range, the lower vertical plane being shifted outwards from the upper vertical plane, wherein the lower portion has a refractory lining; the second wall portion is vertical and has an outermost tube next to the corner, wherein the outermost tube of the second wall portion is in the lower level region connected to the outermost tube of the first wall portion by a planar lower beveled corner fin having a refractory lining and a width that is greater than the first width.