Premixing Device Baffle Design for Low-Flow Fuel-Air Ratio Control
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Solution Overview
Problem
Existing premixing devices face challenges in generating an appropriate amount of fuel gas due to insufficient negative pressure, leading to an inappropriate fuel lean mixture ratio and reduced turndown ratio, especially at low air flow rates and velocities.
Innovation Solution
The premixing device incorporates a baffle within the divided flow paths to increase the air flow velocity in the outer region, preventing air from joining together near the fuel gas outlet and enhancing the negative pressure effect, thereby allowing an appropriate amount of fuel gas to flow out.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the opening area of the divided flow paths is reduced to increase air flow velocity, then the flow velocity increases, but the flow path resistance increases causing pressure loss
Solution Approach 1:
The flow path is divided into inner and outer regions using a baffle, allowing differential flow velocity control. The inner region has restricted flow area to increase velocity and negative pressure, while the outer region maintains larger area to reduce overall flow path resistance and pressure loss.
Solution Approach 2:
Different regions of the flow path are given different flow characteristics. The inner region near the blade has high velocity and strong negative pressure for fuel gas suction, while the outer region has lower velocity and lower resistance for efficient air flow, optimizing both functions simultaneously.
2Use of energy by moving object
If air flow rate is small and air flow velocity is low, then energy consumption is reduced, but negative pressure generation is insufficient making it difficult to flow out appropriate amount of fuel gas
Solution Approach 1:
The flow path is segmented into inner and outer regions, enabling the inner region to generate sufficient negative pressure through restricted area even at low overall flow rates, while the outer region maintains low resistance to minimize energy consumption.
Solution Approach 2:
The flow path area parameter is changed spatially within the flow path using a baffle, creating regions of different cross-sectional areas. This allows the same air flow rate to produce different velocities in different regions, enabling sufficient negative pressure generation without increasing overall energy consumption.
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 configuration increases the turndown ratio by ensuring an appropriate fuel-to-air mixture ratio even at low air flow rates, while minimizing pressure loss and flow path resistance.
Implementation Method 1
The baffle is provided in at least a portion of an inner region on the blade side of each of the divided flow paths, and is configured to increase a flow velocity of air flowing through an outer region opposite the inner region to be higher than a flow velocity of air passing through the inner region
Implementation Method 2
the fuel gas outlet allowing a fuel gas to flow out to the gas flow path by utilizing a negative pressure generated due to effects of a flow of the air
Implementation Method 3
by utilizing a negative pressure generated due to effects of a flow of the air, it is possible to cause a fuel gas to flow out from the fuel gas outlet to the gas flow path, and generate a mixed gas of the fuel gas and the air
Data Source
AI summary
A premixing device includes: a blade, arranged midway of a gas flow path through which air flows, and provided with a fuel gas outlet in a region near one end downstream in an air flow direction; a pair of divided flow paths, configured by dividing a portion of the gas flow path by the blade; and a baffle, located upstream of the fuel gas outlet in the air flow direction on an inner peripheral surface of each divided flow path, and being in the shape of a protruding piece or step part protruding inward of each divided flow path. The baffle is provided in at least a portion of an inner region of each divided flow path, and makes it possible to increase a flow velocity of air flowing through an outer region to be higher than a flow velocity of air passing through the inner region.