Premixing Device With Bulging Blades For Low Pressure Loss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing premixing devices face challenges in generating sufficient negative pressure for fuel gas outflow at low air flow rates, leading to a low turndown ratio and increased pressure loss.
Innovation Solution
The premixing device incorporates a Venturi-shaped gas flow passage with internal blade portions featuring inner and outer bulging portions that squeeze air flow paths, enhancing negative pressure generation and reducing pressure loss by maintaining equal flow path areas near the center and ends, and positioning the fuel gas outlet in a concave portion to prevent vortex interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If air flow rate is increased to generate sufficient negative pressure for fuel gas outflow, then fuel gas mixing performance is improved, but pressure loss increases and turndown ratio decreases
Solution Approach 1:
The gas flow passage is designed with different cross-sectional areas at different locations: a first cross-sectional area at the upstream end, a smaller second cross-sectional area at the downstream end, and a third cross-sectional area at the fuel gas outlet that is smaller than both. This local variation in geometry creates different flow characteristics and negative pressure zones at specific locations, enabling effective fuel gas outflow at lower overall air flow rates while minimizing pressure loss across the entire system.
Solution Approach 2:
The invention changes the geometric parameters of the gas flow passage, specifically the cross-sectional areas at different positions. By optimizing the ratio between the first, second, and third cross-sectional areas, the system achieves sufficient negative pressure at the fuel gas outlet for proper fuel gas outflow even at reduced air flow rates, thereby improving turndown ratio and reducing overall pressure loss.
2Loss of energy
If air flow rate is reduced to decrease pressure loss, then energy efficiency is improved, but negative pressure generation is insufficient and fuel gas outflow is inadequate
Solution Approach 1:
The gas flow passage is designed with different cross-sectional areas at different locations: a first cross-sectional area at the upstream end, a smaller second cross-sectional area at the downstream end, and a third cross-sectional area at the fuel gas outlet that is smaller than both. This local variation in geometry creates different flow characteristics and negative pressure zones at specific locations, enabling effective fuel gas outflow at lower overall air flow rates while minimizing pressure loss across the entire system.
Solution Approach 2:
The invention changes the geometric parameters of the gas flow passage, specifically the cross-sectional areas at different positions. By optimizing the ratio between the first, second, and third cross-sectional areas, the system achieves sufficient negative pressure at the fuel gas outlet for proper fuel gas outflow even at reduced air flow rates, thereby improving turndown ratio and reducing overall pressure loss.
3Ease of manufacture
If conventional gas flow passage geometry is used, then manufacturing is simple, but turndown ratio is low and mixing performance at low flow rates is poor
Solution Approach 1:
The gas flow passage is designed with different cross-sectional areas at different locations: a first cross-sectional area at the upstream end, a smaller second cross-sectional area at the downstream end, and a third cross-sectional area at the fuel gas outlet that is smaller than both. This local variation in geometry creates different flow characteristics and negative pressure zones at specific locations, enabling effective fuel gas outflow at lower overall air flow rates while minimizing pressure loss across the entire system.
Solution Approach 2:
The invention changes the geometric parameters of the gas flow passage, specifically the cross-sectional areas at different positions. By optimizing the ratio between the first, second, and third cross-sectional areas, the system achieves sufficient negative pressure at the fuel gas outlet for proper fuel gas outflow even at reduced air flow rates, thereby improving turndown ratio and reducing overall pressure loss.
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 ensures effective fuel gas mixing at varying air flow rates, increasing the turndown ratio and reducing pressure loss, even at low fan rotation speeds, by optimizing air flow velocity and negative pressure generation.
Implementation Method 1
The gas flow passage 40 has a Venturi shape, to which a part is connected where a flow path area of an upstream region thereof gradually decreases while a flow path area of a downstream region gradually increases. As shown in FIG. 9B, the two vertical and horizontal blade portions 9A and 9B are arranged in a state of being connected in a cross shape in a side view, and a fuel gas outlet 60 is arranged at a rear end portion on the downstream side in these gas flow directions. The blade portions 9A and 9B have an internal hollow shape, and fuel gas is supplied into the blade portions 9A and 9B from the periphery of the tubular member 4e. In the premixing device Ae, air flows through the gas flow passage 40 and a negative pressure is generated near the fuel gas outlet 60. Thereby, fuel gas flows out from the fuel gas outlet 60 to the gas flow passage 40 and is mixed with air. Because the gas flow passage 40 has the Venturi shape, flow velocity of air can be increased and the negative pressure can be generated.
Implementation Method 2
At least one of a pair of surfaces of the first and second blade portions facing each other is equipped with an inner bulging portion that bulges in the z direction so as to squeeze a part of the air flow path near the center of the gas flow passage
Data Source
AI summary
A premixing device includes: a gas flow passage forming member in which an x direction is used as an axial length direction, and a Venturi-shaped gas flow passage into which air can flow in from the outside is formed inside; and a blade portion positioned in the gas flow passage, extending in a y direction, and equipped with a fuel gas outlet. The blade portion includes first and second blade portions spaced apart from each other in a z direction, and an air flow path near the center through which a part of the air flows is formed between these first and second blade portions. At least one of a pair of surfaces of the first and second blade portions facing each other is equipped with an inner bulging portion that bulges in the z direction so as to squeeze a part of the air flow path near the center.