Variable Cross-Section Water-Cooled Column for Circulating Fluidized Bed Boiler

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Solution Overview

Problem

Large-scale circulating fluidized bed boilers face challenges in efficiently distributing secondary air and arranging heat plates due to unbalanced growth between heat release and absorption, leading to constraints in size and parameter advancements, with conventional water-cooled columns requiring larger spaces for conduits and maintenance, complicating the design and affecting material mixing and heating plate arrangement.

Innovation Solution

A water-cooled column with a variable cross-section design, where the lower part has a larger cross-sectional area to accommodate secondary air tubes and maintenance, and the upper part has a smaller area to minimize interference with the heating plate, allowing for a more spacious and simplified structure with inclined side walls that reduce the distance between furnace walls, thereby improving air distribution and reducing abrasion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a conventional water-cooled column is designed with sufficient cross-sectional area to accommodate secondary air conduits and maintenance space, then the space for arranging conduits and maintenance is improved, but the distance between inner and outer walls of the combustion chamber decreases, adversely affecting material mixing and heating plate arrangement

Engineering Contradiction:
Improvespace for arranging conduits and maintenanceVSAvoiddistance between inner and outer walls of combustion chamber
Core Design Contradiction:
Ease of operationVSVolume of moving object

Solution Approach 1:

The water-cooled column is segmented into multiple sections with different cross-sectional areas along its height. The lower section has a larger cross-sectional area to accommodate conduits and maintenance space, while the upper section has a smaller cross-sectional area to maintain sufficient distance between walls. This segmentation allows each section to independently fulfill its specific functional requirements without compromising the other.

Inventive Principle:
Principle #1Segmentation

2Device complexity

If only one conventional square water-cooled column is disposed inside the chamber, then the structure is simplified, but the lower parts of four water-cooled sidewalls must be inclined inwardly to provide combustion space, making the design and arrangement of water-cooled sidewalls complicated

Engineering Contradiction:
Improvestructure of water-cooled columnVSAvoiddesign and arrangement of water-cooled sidewalls
Core Design Contradiction:
Device complexityVSEase of manufacture

Solution Approach 1:

The water-cooled column is divided into an upper section and a lower section with different geometric characteristics. The upper section maintains a square cross-section for structural simplicity, while the lower section transitions to a smaller cross-section to accommodate the combustion chamber's spatial requirements. This segmentation allows the sidewalls to be designed with different orientations in different zones, simplifying the overall manufacturing process.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The water-cooled column transitions from a uniform cross-section design to a variable cross-section design along the vertical dimension. By changing the cross-sectional area along the height of the column, the design accommodates the combustion chamber's space requirements without complicating the sidewall arrangement, as the dimensional change occurs along the vertical axis rather than requiring complex lateral adjustments.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Volume of stationary object

If the cross section of the water-cooled column is reduced, then the volume of the water-cooled column is reduced, but the space for arranging secondary air tubes and maintenance is reduced

Engineering Contradiction:
Improvevolume of water-cooled columnVSAvoidspace for arranging secondary air tubes and maintenance
Core Design Contradiction:
Volume of stationary objectVSEase of operation

Solution Approach 1:

The water-cooled column is segmented into sections with different cross-sectional areas. The lower section maintains a larger cross-sectional area specifically dedicated to accommodating secondary air tubes and providing maintenance space, while the upper section reduces its cross-sectional area to minimize the overall volume. This segmentation ensures that the reduced volume does not compromise the operational space requirements.

Inventive Principle:
Principle #1Segmentation

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 design significantly reduces the volume of the water-cooled column, allowing for easier arrangement of secondary air tubes and maintenance, minimizes interference with the flow field, and simplifies the structure of the furnace side walls, enhancing the operational efficiency and scalability of large-size circulating fluidized bed boilers.

Implementation Method 1

water-cooled column formed by water-cooled membrane walls

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

working medium is passed through a tube of the water-cooled membrane wall from bottom to top

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP3045809B1Circulating fluidized bed boiler furnace having a variable cross-section water-cooled cylinder
Publication Date: 2019.05.29 INST OF ENGINEERING THERMOPHYSICS - CHINESE ACAD OF SCI
  • EP3045809B1 patent drawingFigure 1~5
  • EP3045809B1 patent drawingFigure 6~9
  • EP3045809B1 patent drawingFigure 10~14

AI summary

Embodiments of the invention provide a water-cooled column formed by side walls connected together to define an enclosed space, each side wall is formed of a water-cooled membrane wall, a working medium is passed through a tube of the water-cooled membrane wall from bottom to top, the water-cooled column comprising: a lower part having a cross section reduced segment, which has a cross section gradually reduced in a direction from bottom to top; and an upper part, wherein the upper part connects with the cross section reduced segment at a connection position, and a cross sectional area of the cross section reduced segment at the connection position is identical to a cross sectional area of the upper part at the connection position. Embodiments of the invention also provide a furnace for defining a reaction space, which comprises a water-cooled column defined as above disposed along a vertical direction therein.