Three-Stage Air-Staged Burner for Low NOx Emissions
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing burner systems fail to achieve low nitrogen oxide (NOx) emissions, carbon monoxide (CO), and hydrocarbon (HC) emissions across a wide range of temperatures and firing rates, while also maintaining a stable flame for uniform heat flux, especially during cold furnace startups and high-temperature operations, and are often costly due to additional air and fuel connections.
Innovation Solution
A three-stage air-staged burner system with a port block design that controls combustion air distribution, featuring a primary and secondary air chamber, a nozzle section with swirl rack, and a fuel passageway with bleed holes, allowing for adjustable air staging and fuel injection to create a stable, flat flame across varying temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If combustion air preheating is used to reduce fuel consumption, then energy efficiency is improved, but nitrogen oxide (NOx) emissions increase exponentially
Solution Approach 1:
The combustion air is divided into multiple stages (primary air, secondary air, tertiary air) that are introduced at different locations and times during the combustion process. This segmentation allows the combustion to occur in distinct zones with controlled oxygen availability, enabling preheated air to be used while maintaining lower peak temperatures that reduce NOx formation.
Solution Approach 2:
Different regions of the combustion chamber are provided with different air temperatures and compositions. The primary combustion zone receives preheated primary air for efficient combustion, while secondary and tertiary zones receive cooler air to control peak temperatures and reduce NOx formation in those regions.
2Object-generated harmful factors
If air staging is used to reduce NOx emissions, then harmful emissions are reduced, but device complexity increases due to additional piping and controlling
Solution Approach 1:
The air staging system combines multiple air delivery functions into an integrated burner design where primary, secondary, and tertiary air passages are built into the burner structure itself. This merging of functions into a single unit eliminates the need for separate external piping systems and complex control mechanisms for each air stage.
Solution Approach 2:
The burner design incorporates automatic air staging control through its internal structure, where the flow of combustion air through different passages is self-regulated by the combustion process itself and the burner geometry, eliminating the need for external control systems.
3Object-generated harmful factors
If regenerative beds are added to the burner body for air staging, then NOx emissions are reduced, but maintenance and installation costs increase
Solution Approach 1:
The complex regenerative bed components are removed from the burner design. Instead, the patent uses a simplified air staging approach with separate air passages that achieve NOx reduction through controlled air distribution without requiring maintenance-intensive regenerative materials.
Solution Approach 2:
The design replaces expensive, maintenance-heavy regenerative beds with simpler, more durable air passage structures that achieve the same NOx reduction goal through geometric design rather than consumable regenerative materials.
4Reliability
If ambient air connection is added for flame stabilization during cold startup, then flame stability is improved, but device complexity and operation costs increase
Solution Approach 1:
The burner design incorporates a pilot ignition system and preheating capability that prepares the combustion chamber and air passages before main combustion begins. This preliminary action ensures stable flame establishment during cold startup without requiring additional ambient air connections.
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 system achieves very low NOx, CO, and HC emissions, maintains a stable flame for uniform heat flux, and reduces emissions without additional air or fuel connections, operating effectively from low to high temperatures with adjustable air staging.
Implementation Method 1
a swirl rack configured to impart a rotational motion to the stage 3 air as the stage 3 air is provided to a cavity of a port block
Implementation Method 2
The port block includes an annular cavity having a first annular section having a substantially constant cross-section and a second annular section having an expanding cross-section
Implementation Method 3
The burner includes an air inlet section, a burner body, a fuel passageway and a nozzle section
Data Source
AI summary
A low NOx burner system is disclosed that reduces the emission of CO and HC during cold furnace startups, minimizes NOx formation with preheated air, and provides a flat stable flame due to burner design improvements including three stage combustion. The burner system is designed to operate in either a low or high temperature mode by controlling the amount of combustion air provided to stage 1 and stage 2 combustion. The burner system is designed to heat the interior of a furnace for high-temperature combustion/furnace processes, such as aluminum melting and steel processes. The burner system can also be used for low temperature processes at temperatures below the auto-ignition temperature of the fuel and still produce very low CO, HC and NOx emissions.