Premixing Device Flapper Control for Ignition Air-Fuel Ratio
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Solution Overview
Problem
Existing premixing devices face challenges in maintaining good flapper responsiveness, appropriate air-fuel ratios, and ignition performance under varying conditions such as air temperature, humidity, and fuel gas composition.
Innovation Solution
A premixing device with a flapper that is rotatable around an axis intersecting the air flow direction, and an operation regulating part that allows the flapper's opening degree to change with air flow rate, with selectively switchable upper limit positions for normal combustion and ignition, optimizing air-fuel ratios for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the discharge energy of the ignition device is increased to improve ignition performance, then ignition performance is improved, but the size and cost of the ignition device increases
Solution Approach 1:
The patent changes the air-fuel ratio parameter by controlling the flapper's opening degree to create a fuel-rich mixture during ignition. This parameter change allows standard ignition devices to achieve reliable ignition without increasing their size or cost, as the improved ignition performance comes from optimizing the combustible mixed gas composition rather than upgrading the ignition device itself
2Reliability
If a butterfly valve is used to reduce valve opening degree at ignition, then ignition performance is improved, but responsiveness to air flow rate changes deteriorates
Solution Approach 1:
The patent segments the gas flow path into multiple paths and uses a flapper that can selectively close individual paths rather than using a single butterfly valve for the entire flow. This segmentation allows the flapper to quickly respond to air flow rate changes by closing specific paths while maintaining overall system responsiveness, unlike a single butterfly valve that would need to modulate its opening degree continuously
Solution Approach 2:
The flapper is designed to dynamically adjust its position based on real-time air flow rate conditions, switching between fully open, partially open, and fully closed states. This dynamic behavior allows rapid response to changing air flow rates while still achieving the fuel-rich mixture needed for ignition when conditions require it
3Speed
If the flapper opening degree is increased to improve flapper responsiveness, then flapper responsiveness is improved, but the ability to maintain appropriate air-fuel ratio deteriorates
Solution Approach 1:
The patent applies local quality by creating different air-fuel mixture compositions in different regions of the gas flow path. The flapper selectively closes certain paths to concentrate fuel gas in specific areas, ensuring appropriate air-fuel ratios are maintained locally where combustion occurs, while the flapper itself can respond quickly to overall air flow rate 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 solution achieves good flapper responsiveness, maintains appropriate air-fuel ratios, and enhances ignition performance by optimizing the flapper's operation based on air flow rates and combustion modes.
Implementation Method 1
air flows in the gas flow path and a negative pressure is generated in the vicinity of the gas outlet, so that the fuel gas flows out from the gas outlet to the gas flow path and is mixed with the air
Data Source
AI summary
A premixing device includes: a gas flow path for allowing air to flow; a gas outlet that allows fuel gas to flow out into the gas flow path by utilizing a negative pressure; and a flapper disposed in the gas flow path. The premixing device further includes an operation regulating part for the flapper which allows the opening degree of the flapper to change according to the air flow rate in a range below a predetermined upper limit position while preventing the flapper from rotating in an opening direction beyond the upper limit position. The operation regulating part is capable of selectively switching and setting one of a first upper limit position for normal combustion and a second upper limit position for fuel ignition. The opening degree of the flapper at the second upper limit position is smaller than that at the first upper limit position.