Burner Air-Fuel Ratio Control via Density Measurement
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Solution Overview
Problem
Conventional burner systems for heating water struggle with maintaining efficient combustion due to variations in air temperature and barometric pressure, leading to excessive excess air and reduced efficiency, as they rely on volume control systems that do not account for changes in air and fuel density, resulting in increased fuel consumption and emissions.
Innovation Solution
A system that measures combustion air temperature and barometric pressure to adjust fan speed, thereby controlling the air flow into the burner, maintaining an optimal air-fuel ratio by directly addressing changes in air density through a controller and fan speed drive signal, without the need for complex fully metered control systems or real-time combustion analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a volume control system is used to control air and fuel flow, then the system is simple to operate, but the air-fuel ratio becomes inaccurate due to density variations with temperature and pressure
Solution Approach 1:
The system changes the control parameter from volume flow (simple to measure) to mass flow (accurate for combustion). By using density sensors to measure actual air and fuel densities and adjusting the control system accordingly, the invention maintains accurate air-fuel ratio control while preserving ease of operation through automated density-based adjustments.
2Reliability
If excess air is increased to ensure complete combustion at all times, then combustion reliability is improved, but energy efficiency deteriorates due to heating excess air
Solution Approach 1:
The system uses feedback from density sensors to continuously monitor and adjust air and fuel flow. By measuring actual densities and comparing them to required ratios, the system automatically adjusts excess air levels to maintain complete combustion while minimizing energy loss, resolving the contradiction between reliability and efficiency.
Solution Approach 2:
The system dynamically adjusts excess air levels based on real-time density measurements rather than using fixed settings. This dynamic adjustment allows the system to maintain optimal combustion conditions under varying temperature and pressure conditions, improving both reliability and efficiency simultaneously.
3Ease of manufacture
If the burner is designed for operation at standard temperature and pressure, then manufacturing cost is reduced, but performance deteriorates under varying temperature and pressure conditions
Solution Approach 1:
The system maintains simple manufacturing by using standard design parameters while achieving adaptability through automated density-based control. The control system adjusts air and fuel flow based on measured densities, allowing the burner to adapt to varying temperature and pressure conditions without requiring complex mechanical adjustments or expensive specialized components.
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 approach ensures a more stable and efficient combustion process by maintaining the air-fuel ratio within a narrower range, reducing excess air, improving energy savings, and extending burner longevity while being cost-effective and easily adaptable to existing systems.
Implementation Method 1
a barometric pressure sensor for providing a first indicator signal to a controller
Implementation Method 2
a combustion air temperature sensor for providing a second indicator signal to the controller
Implementation Method 3
a fan motor for driving an air inlet fan of the oil fueled burner
Implementation Method 4
processing them according to a predetermined relationship to provide a fan speed drive signal
Data Source
AI summary
A method and apparatus that applies corrections to the mass flow rate of combustion air into a gas or oil-fired, forced-draft burner, and thus provides for correcting the air-fuel ratio, by directly measuring the combustion air temperature and/or the barometric pressure of the combustion air, and using these measurements to develop a fan speed drive signal that corrects the volume of air inlet to the burner system without the use of the complex and expensive fully metered control systems, or elaborate feedback systems, or systems that require real-time combustion analysis, and the like.