Premixing Device Flapper and Protruding Wall for Turn-Down Ratio
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Solution Overview
Problem
Existing premixing devices face challenges in maintaining an appropriate mixing ratio and increasing the turn-down ratio due to issues such as fuel gas leakage, backflow of air, and sudden changes in air flow velocity.
Innovation Solution
The premixing device incorporates a first blade section with a protruding wall section and a flapper that oscillates to open and close both the first flow path and the first fuel gas outlet, suppressing air flow into the first fuel gas outlet and maintaining a stable mixing ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a flapper is used to open and close the first flow path, then the turn-down ratio is increased, but fuel gas may continue to flow out from the first fuel gas outlet and air may backflow into the outlet, making it difficult to maintain the desired mixing ratio
Solution Approach 1:
The invention divides the control function into two separate components: a flapper for controlling the first flow path and a protruding wall section for controlling the first fuel gas outlet. This segmentation allows each component to perform its specific function independently, preventing fuel gas leakage and air backflow while maintaining the turn-down ratio benefit of the flapper mechanism.
Solution Approach 2:
The protruding wall section acts as an intermediary element between the first fuel gas outlet and the first flow path. It serves as a mediator that prevents direct communication between the outlet and the flow path when the flapper is closed, thereby preventing fuel gas leakage and air backflow while allowing the flapper to maintain its flow control function.
2Reliability
If an additional flapper is provided to open and close the first fuel gas outlet, then fuel gas leakage is prevented, but the total number of parts increases, resulting in higher manufacturing costs
Solution Approach 1:
The invention extracts the flow control function from the flapper and assigns it to a separate protruding wall section. This extraction allows the flapper to focus solely on controlling the first flow path while the protruding wall section handles the fuel gas outlet control, preventing fuel gas leakage without requiring a second flapper and thereby reducing overall device complexity.
Solution Approach 2:
Instead of using another flapper to control the fuel gas outlet, the invention inverts the approach by using a fixed protruding wall section that works in conjunction with the existing flapper. This inversion simplifies the structure by replacing a movable component (second flapper) with a simpler fixed structure (protruding wall section).
3Ease of operation
If the flapper changes from a closed state to an open state, then air flow is restored to the first flow path, but the effective flow path area changes abruptly, causing air flow velocity to rapidly decrease and the mixing ratio to become fuel lean
Solution Approach 1:
The protruding wall section is positioned in advance to prevent air from entering the first fuel gas outlet when the flapper opens. This preliminary preventive action ensures that air does not suddenly enter the system when the flapper transitions from closed to open state, thereby preventing abrupt changes in flow velocity and mixing ratio while allowing smooth flow path control.
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 effectively increases the turn-down ratio while maintaining an appropriate mixing ratio by preventing fuel gas leakage and air backflow, and stabilizing air flow velocity.
Implementation Method 1
The flapper is configured to change the opening degree thereof in response to the air flow rate, such that when the air flow rate in the first flow path is low, the opening degree is smaller than when the air flow rate is high
Implementation Method 2
the flow of air from the first flow path to the first fuel gas outlet is suppressed by the protruding wall section
Implementation Method 3
when air flows through the premixing flow path and negative pressure acts on the first fuel gas outlet and the second fuel gas outlet, fuel gas flows out from the first fuel gas outlet and the second fuel gas outlet into the premixing flow path
Implementation Method 4
The premixing flow path is partitioned into a first flow path and a second flow path by a partition wall section
Implementation Method 5
The fuel gas mixes with the aforementioned air, generating a mixture
Data Source
AI summary
A premixing device which includes a premixing flow path including a first flow path and a second flow path, and a first fuel gas outlet and a second fuel gas outlet includes: a first blade section which is provided in the first flow path, and with which the first fuel gas outlet is provided; a protruding wall section which is provided on the first blade section; and a flapper which oscillates at a position downstream in the air flow direction than the first blade portion of the first flow path. When the flapper is in an open state below a specified opening degree, the flow of air from the first flow path to the first fuel gas outlet is capable of being suppressed by the protruding wall section.