Asymmetric Refractory Brick for Combustion Chamber Integrity

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Solution Overview

Problem

Refractory bricks in static combustion chambers face both reversible thermal deformation and irreversible chemical deformation due to high temperatures and corrosive atmospheres, leading to mechanical stresses and potential unhooking or breaking, which compromises the integrity of the boiler operation.

Innovation Solution

Designing refractory bricks with specific geometric features, such as parallel polygon bases and beveled sides, and made from materials like silicon carbide with oxide or nitride bonds, to anticipate and manage deformations, ensuring the bricks remain securely attached and functional despite thermal and chemical stresses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If refractory bricks are used in static combustion chambers, then heat transmission and corrosion protection functions are achieved, but irreversible chemical deformation and thermal deformation cause mechanical stresses leading to brick unhooking or breaking

Engineering Contradiction:
Improvebrick structural integrityVSAvoidbrick resistance to mechanical stress
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The brick is pre-formed with a specific geometric shape featuring a hot face that is larger than the cold face, anticipating the deformation that will occur during service. This preliminary shaping ensures that when thermal and chemical deformation occur, the brick maintains contact with the retention structure rather than detaching

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The brick employs an asymmetric geometry where the hot face area is deliberately made larger than the cold face area. This asymmetry compensates for the uneven deformation distribution, with the larger hot face accommodating the greater expansion and chemical deformation that occurs in the high-temperature zone

Inventive Principle:
Principle #4Asymmetry

2Ease of manufacture

If bricks are designed with standard geometric shapes, then manufacturing is simplified, but deformation under thermal and chemical stress causes loss of sealing and exposure of tubes to corrosive fumes

Engineering Contradiction:
Improvebrick manufacturing simplicityVSAvoidcombustion chamber sealing integrity
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The invention uses an asymmetric brick design where the hot face is larger than the cold face. This geometric asymmetry is specifically tailored to match the deformation pattern under thermal and chemical stress, ensuring that the brick maintains proper positioning and sealing function while remaining manufacturable

Inventive Principle:
Principle #4Asymmetry

3Use of energy by moving object

If bricks are subjected to high temperatures and corrosive atmospheres, then heat transmission to tubes is effective, but chemical deformation causes bricks to deform and break

Engineering Contradiction:
Improveheat transmission efficiencyVSAvoidbrick dimensional stability
Core Design Contradiction:
Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The brick is pre-shaped with a larger hot face area before installation, anticipating the chemical deformation that will occur during service. This preliminary geometric adjustment ensures that when the brick undergoes chemical deformation in the corrosive atmosphere, the deformation is accommodated within the designed geometry rather than causing structural failure

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention changes the geometric parameters of the brick, specifically making the hot face area larger than the cold face area. This parameter modification allows the brick to accommodate dimensional changes due to chemical deformation while maintaining structural integrity and functional performance

Inventive Principle:
Principle #35Parameter changes

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 modified brick design effectively anticipates and accommodates deformations, reducing mechanical stresses and preventing unhooking or breaking, thus maintaining the structural integrity and operational efficiency of the combustion chamber.

Implementation Method 1

the bricks are subjected to high temperatures (typically 1200°C to 950°C in smoke temperature) and to aggressive atmospheres... the chemical deformation and the thermal deformation cause the bricks to deform in the form of a banana

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

the chemical deformation and the thermal deformation cause the bricks to deform... typical during incineration of certain waste or biomass

Methodology Applied
Scientific EffectChemical deformation: Oxidation

Data Source

PatentEP2857750B1Shaped refractory brick
Publication Date: 2019.04.03 VEOLIA PROPRETE
  • EP2857750B1 patent drawingFigure 1~3
  • EP2857750B1 patent drawingFigure 4~6
  • EP2857750B1 patent drawingFigure 7~9

AI summary

The invention relates to a refractory brick (100, 200) for the wall of a static combustion chamber subjected to corrosive atmospheres, comprising a hot face (HF) having a width (W_h) and a length (L_h); and comprising a cold face (CF), opposite the hot face (HF), having a width (W_c) and a length (L_c), and intended to be near or in contact with at least one tube for the flow of a heat transfer fluid, the cold face (CF) being equipped with a blind recess (103, 203) for fixing the brick to a wall fixing device. It is essentially characterized in that: the width of the hot face is less than the width of the cold face, or the length (L_h) of the hot face is less than the length (L_c) of the cold face, such that at least two opposite lateral faces have a bevel of angle θ.