Premix Burner Throttle Control for Main Valve Open Trouble
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Solution Overview
Problem
Existing premixing apparatuses fail to prevent fuel gas emission during post-purge operations due to main valve open troubles, leading to poor combustion and inefficiencies.
Innovation Solution
A premixing apparatus with a controller that regulates the opening degree of a variable throttle valve based on flame current detection, ensuring the excess air ratio is maintained, and includes controls to extinguish the burner and minimize fuel gas emission during post-purge operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the main valve is closed during combustion suspension, then fuel gas emission is prevented under normal conditions, but if the main valve has an open trouble, fuel gas is emitted during post-purge operation
Solution Approach 1:
The patent introduces a variable throttle valve as an intermediary component between the main valve and the burner. This throttle valve acts as a backup control mechanism that can independently regulate fuel gas flow when the main valve fails to close properly, preventing fuel gas emission during post-purge operations even when the main valve has an open trouble
Solution Approach 2:
The patent implements a feedback control system where the controller monitors the state of the main valve and the operation mode of the burner. Based on this feedback information, the controller automatically adjusts the opening degree of the variable throttle valve to maintain proper fuel gas flow control, particularly during post-purge operations when the main valve should be closed
2Productivity
If the variable throttle valve opening degree is adjusted to maintain excess air ratio, then combustion efficiency is improved, but during post-purge operation with main valve open trouble, fuel gas emission occurs
Solution Approach 1:
The patent makes the variable throttle valve dynamic by enabling its opening degree to change based on operational conditions. During normal combustion, it maintains the excess air ratio for efficient combustion. During post-purge operation, when the main valve is closed, the controller adjusts the throttle valve to a predetermined opening degree that prevents fuel gas emission while accounting for potential main valve failures
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
Effectively prevents fuel gas emission and ensures prompt ignition by maintaining the excess air ratio, reducing costs by eliminating the need for additional emission prevention components.
Implementation Method 1
a flame rod that is exposed in flames of the burner; and a controller, wherein the controller is configured to carry out a first control that regulates an opening degree of the variable throttle valve so that an excess air ratio of the air-fuel mixture, which is indexed based on a flame current that is detected by the flame rod
Data Source
AI summary
In a premixing apparatus that mixes a fuel gas with air and supplies an air-fuel mixture to a burner through a fan, includes a main valve, a zero governor, and a variable throttle valve which are interposed from an upstream side downward in sequence in a gas supply passage, of which an downstream end is connected to a gas suction part that is provided in an air supply passage on an upstream side of a fan, and carries out a first control that regulates an opening degree of the variable throttle valve so that an excess air ratio of the air-fuel mixture, which is indexed based on a flame current that is detected by a flame rod which is exposed in flames of the burner, and a second control that, at time of a post-purge operation, if the flame rod detects the flame current, it will be decided that an open trouble of the main valve occurs and the opening degree of the throttle valve will be tightened till a minimum opening-degree which is set so that the burner is extinguished.