Oxygen Enrichment in Premix Burners via Circumferential Injection

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Solution Overview

Problem

Conventional premix burners face challenges in safely and efficiently enriching combustion with significant oxygen due to the risk of flame flashback and overheating of burner components, limiting oxygen enrichment to low levels.

Innovation Solution

A premix burner arrangement and method that introduces oxygen circumferentially around a central air-fuel gas stream at a lower velocity ratio, inhibiting mixing and maintaining a temperature difference of at least 1000°F to prevent overheating, allowing for higher oxygen enrichment while minimizing burner component damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If significant additional oxygen is added directly to the premix combustion mixture, then oxygen enrichment level is improved, but flame flashback risk increases

Engineering Contradiction:

Improveoxygen enrichment levelVSAvoidflashback risk

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The oxygen injection system is segmented into multiple circumferential nozzles arranged around the central air-fuel stream, allowing distributed oxygen addition rather than concentrated injection. This segmentation prevents localized high oxygen concentrations that could trigger flashback while achieving overall enrichment.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Oxygen is injected with different properties (lower velocity, lower temperature) than the central air-fuel stream. The velocity ratio is controlled to be less than 1.0, creating a velocity differential that prevents oxygen from penetrating into the combustion zone and causing flashback.

Inventive Principle:

Principle #3Local quality

2Productivity

If oxygen is premixed with fuel at high velocity, then combustion efficiency is improved, but flame speed increases causing flashback

Engineering Contradiction:

Improvecombustion efficiencyVSAvoidflame speed

Core Design Contradiction:

ProductivityVSSpeed

Solution Approach 1:

The oxygen injection is extracted from the central premix stream and placed in a separate circumferential position. This prevents oxygen from directly premixing with fuel at high velocity while still allowing combustion to occur as the oxygen diffuses into the flame zone.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of injecting oxygen into the center where fuel flows, the patent inverts the arrangement by flowing oxygen circumferentially around the central air-fuel stream. This reversal prevents direct high-velocity mixing that would increase flame speed.

Inventive Principle:

Principle #13The other way round (Inversion)

3Quantity of substance

If high velocity oxygen is injected into the burner, then oxygen enrichment is improved, but burner component overheating increases

Engineering Contradiction:

Improveoxygen enrichment levelVSAvoidburner component temperature

Core Design Contradiction:

Quantity of substanceVSTemperature

Solution Approach 1:

The oxygen stream parameters are changed to have lower velocity and lower temperature compared to the air-fuel stream. The velocity ratio is maintained below 1.0, and the temperature differential is kept at least 1000°F, preventing the oxygen stream from contributing to burner component overheating.

Inventive Principle:

Principle #35Parameter changes

4Productivity

If oxygen velocity is increased to improve mixing, then enrichment efficiency is improved, but flashback risk increases

Engineering Contradiction:

Improveenrichment efficiencyVSAvoidflashback risk

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

Different velocity qualities are assigned to different streams: the central air-fuel stream maintains high velocity for proper atomization and mixing, while the circumferential oxygen stream uses lower velocity to prevent flashback. This differential velocity approach enables enrichment without increasing flashback risk.

Inventive Principle:

Principle #3Local quality

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

Enables safe and efficient oxygen enrichment of premix combustion, reducing the risk of flashback and overheating, thereby achieving higher oxygen levels without damaging burner components.

Implementation Method 1

The premix burner arrangement is configured to combust or react the first stream at a temperature at least 1000° F. greater than the temperature of the second stream

Methodology Applied

Scientific EffectCombustion: Combustion

Implementation Method 2

The premix burner arrangement is further configured to provide a velocity ratio of the second gas stream to the first gas stream sufficiently low to inhibit mixing of the first gas stream with the second gas stream

Methodology Applied

Scientific EffectFluid flow velocity control:

Data Source

PatentUS9017067B2Oxygen enrichment of premix air-gas burners

Publication Date: 2015.04.28 AIR PROD & CHEM INC

AI summary

A premix burner arrangement for safely oxygen-enriching a premix air-fuel combustion system is disclosed. In the disclosed burner arrangement, a first conduit is arranged and disposed to provide a first gas stream. The first gas stream is a self-reactive or self-flammable premixture comprising air and a combustible gas. At least one second conduit is arranged and disposed to provide a second gas stream circumferentially around the first gas stream. The second gas stream includes oxygen. The premix burner arrangement is configured to combust or react the first stream at a temperature at least 1000° F. greater than the temperature of the second stream. A method and combustion system including the premix burner arrangement are also disclosed.