Premixing Apparatus Turndown Ratio via Segmented Air Paths
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Solution Overview
Problem
Existing heat source apparatuses using combustion of fuel gas have limited turndown ratios, restricting the adjustment range of combustion capacity from minimal to maximal, and require cumbersome control of gas and air supply adjustments.
Innovation Solution
A premixing apparatus with a venturi unit, air supply adjusting unit, and gas switching unit that adjusts air and fuel gas amounts independently, allowing for a wide turndown ratio of 1:15 by varying the number of rotations of the air supply fan and the load on the air, enabling flexible combustion control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the turndown ratio is increased to expand the adjustment range of combustion capacity, then the flexibility of combustion control is improved, but the device complexity increases due to the need for independent adjustment mechanisms for gas and air supply
Solution Approach 1:
The air supply path is divided into multiple segments with different resistance characteristics. The premixing apparatus includes a first air supply path with a first air resistance and a second air supply path with a second air resistance. By selectively switching between these segments, the system achieves multiple discrete air supply levels, enabling a wide turndown ratio without requiring continuous adjustment mechanisms.
Solution Approach 2:
The system dynamically switches between different air supply configurations based on the required combustion level. A switching mechanism selectively connects either the first air supply path or the second air supply path to the mixing chamber, allowing the air supply amount to be adaptively adjusted according to the gas supply amount, thereby achieving flexible combustion control across a wide range.
2Measurement precision
If the air supply amount is adjusted by both fan rotations and butterfly valve, then the adjustment precision is improved, but the ease of operation deteriorates due to the need to coordinate multiple adjustment mechanisms
Solution Approach 1:
The air supply adjustment is segmented into discrete levels achieved by switching between different air supply paths with predetermined resistance values. This eliminates the need for continuous coordination of multiple adjustment mechanisms, as the switching mechanism automatically selects the appropriate air supply level based on the gas supply amount, simplifying operation while maintaining precision.
Solution Approach 2:
The system incorporates feedback control where the switching mechanism responds to the gas supply amount to automatically select the appropriate air supply path. This feedback mechanism ensures that the air supply amount is precisely matched to the gas supply amount without requiring manual coordination of multiple adjustments, thereby improving ease of operation while maintaining adjustment precision.
3Adaptability or versatility
If the premixing apparatus uses multiple air supply paths with different resistances, then the turndown ratio is improved, but the device complexity increases due to additional switching mechanisms
Solution Approach 1:
The air supply system is segmented into multiple paths with different resistance characteristics, each optimized for specific combustion levels. The switching mechanism selectively activates the appropriate path based on the required turndown ratio, achieving high adaptability through structured segmentation rather than complex continuous adjustment mechanisms.
Solution Approach 2:
The switching mechanism serves multiple functions: it selects between different air supply paths, controls the air supply amount, and enables the wide turndown ratio. By consolidating these functions into a single switching mechanism, the system achieves high adaptability without proportionally increasing device complexity.
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 allows for a wide adjustment range of combustion gas amounts, simplifies control mechanisms, and expands the turndown ratio from 1:3 to 1:15, enhancing the efficiency and flexibility of combustion processes without degrading mixing performance.
Implementation Method 1
a venturi unit 4, an air supply adjusting unit 6, and a gas switching unit 8. The venturi unit 4 mixes a fuel gas G and air Ar together
Implementation Method 2
an air supply fan 70 that supplies the air Ar to the venturi unit 4
Data Source
AI summary
A premixing apparatus includes a mixing unit, an air supply adjusting unit, and a gas switching unit. The mixing unit draws a fuel gas in the mixing unit by supplied air to mix the fuel gas and the supplied air with each other. The air supply adjusting unit applies a load on the supplied air flowing toward the mixing unit and switches the load. The gas switching unit switches a gas amount of the fuel gas to be supplied to the mixing unit.