Variable Cross-Section Distributor for Premix Burner Ionisation Stability

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Solution Overview

Problem

Existing premix burners face challenges in maintaining a stable and intense ionisation signal across varying thermal regimes, leading to inefficient combustion control and increased mechanical stress due to thermoacoustic instability, particularly in low thermal flow conditions.

Innovation Solution

A distributor device with a distribution element featuring fixed and movable deflector elements, where the fixed deflector directs the mixture to a specific region for intense ionisation signal detection, and the movable deflector adjusts flow direction based on pressure, ensuring consistent ionisation signal intensity and reduced load losses across thermal power variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a conventional distributor with uniformly directed flow is used, then the structure is simple, but the ionisation signal intensity is insufficient in low thermal flow regimes

Engineering Contradiction:
Improveionisation signal intensityVSAvoiddistributor structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The distributor features a non-uniform deflector configuration where specific deflectors are positioned to create a porous zone with higher mixture flow density in a predetermined region. This local concentration of flow enhances the ionisation signal intensity in that specific area without requiring complete redistribution throughout the entire distributor structure.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The distributor is segmented into different functional zones: a porous zone with higher deflector density for signal enhancement, and other regions with standard deflector configuration. This segmentation allows the system to optimize ionisation detection in specific areas while maintaining overall structural simplicity.

Inventive Principle:
Principle #1Segmentation

2Measurement precision

If the burner operates in low thermal flow regimes, then energy consumption is reduced, but the ionisation signal becomes too weak for effective control

Engineering Contradiction:
Improveionisation signal detectabilityVSAvoidthermal power output
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

By concentrating the mixture flow in a porous zone through strategically positioned deflectors, the system maintains high ionisation signal intensity even when overall thermal power is reduced. This allows effective control signal detection in low energy consumption regimes.

Inventive Principle:
Principle #3Local quality

3Stability of the object's composition

If deflectors are added to direct mixture flow, then fluid dynamic distribution is improved, but mechanical stress and thermoacoustic instability increase

Engineering Contradiction:
Improvefluid dynamic distributionVSAvoidmechanical stress on distributor
Core Design Contradiction:
Stability of the object's compositionVSStress or pressure

Solution Approach 1:

Rather than uniformly distributing deflectors throughout the distributor, the invention places them specifically in regions where flow direction control is most beneficial. This localized approach achieves improved fluid dynamic distribution while minimizing the total number of deflectors and their associated mechanical stresses.

Inventive Principle:
Principle #3Local quality

4Measurement precision

If a porous zone with higher deflector density is created, then ionisation signal intensity increases, but manufacturing complexity increases

Engineering Contradiction:
Improveionisation signal intensityVSAvoiddistributor manufacturing
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The distributor is designed as a segmented structure where the porous zone with higher deflector density is clearly defined and can be manufactured as a distinct module. This segmentation simplifies the manufacturing process by allowing standardized production of different zone configurations.

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

The solution provides a stable and intense ionisation signal across the full operating range, enabling efficient combustion control and reduced mechanical stress, while allowing independent regulation of the air-gas ratio and fluid dynamic distribution, achieving high modulation ratios and minimizing energy consumption.

Implementation Method 1

a fixed deflector element, whose guide surface is oriented in such a way as to direct a part of the flow of mixture in a first fixed direction

Methodology Applied
Scientific EffectFluid flow direction control:

Implementation Method 2

a movable deflector element, which directs a part of the mixture in a second direction and is free to rotate about a joint by effect of the pressure of the mixture

Methodology Applied
Scientific EffectPressure-driven motion: Pressure Gradient

Implementation Method 3

the position of each opening on the second surface is defined uniquely by a respective azimuth angle... in a predetermined region, the intensity of the ionisation signal increases locally

Methodology Applied
Scientific EffectFlow concentration:

Implementation Method 4

the formation of the flame produced by combustion of numerous gases in the presence of an oxidant - air, for example - is accompanied by an ionisation process whereby ions are formed

Methodology Applied
Scientific EffectIonisation: Ionisation

Data Source

PatentEP3628924B1Variable cross-section distributor device for a premixing burner and burner comprising such distributor
Publication Date: 2021.06.02 POLIDORO
  • EP3628924B1 patent drawingFigure 1A~1B
  • EP3628924B1 patent drawingFigure 1C~1D
  • EP3628924B1 patent drawingFigure 2A~2B

AI summary

A variable cross-section distributor for a premix burner is provided with a plurality of openings and deflector elements which are located proximate thereto on an output surface and which have guide surfaces for directing the flow of an air and gas mixture in a plurality of directions. A first deflector element is configured to direct a part of the flow permanently in a first direction towards an ionisation sensor. A movable deflector element, capable of adopting, as a function of the pressure exerted on it by the mixture, a position that is variable relative to the output surface, is used to vary the cross section of the distributor through which the mixture flows and to minimise the load losses; the movable deflector directs a part of the flow in a second variable direction. At least one further, fixed deflector is configured to direct a part of the flow permanently in a second direction, different from the first direction, and to regulate the fluid dynamic distribution output from the distributor.