Variable Equivalence Ratio Ignition for Air-Gas Mixture Appliances
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Solution Overview
Problem
Air-gas mixture burning appliances, particularly those using hydrogen, face risks of delayed ignition leading to explosions, which can damage the appliance and pose safety hazards to nearby individuals.
Innovation Solution
The appliance adjusts the equivalence ratio between gas and air before and after ignition, using a gas supply unit with independent control of gas flow channels and a solenoid-controlled gas valve, to prevent explosive build-ups and ensure stable combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed rich concentration of combustible air-gas mixture is used for ignition, then ignition stability is improved, but the risk of explosion upon delayed ignition increases
Solution Approach 1:
The patent applies dynamics by making the gas concentration dynamic rather than fixed. The system automatically adjusts the gas concentration in the combustible air-gas mixture based on the ignition state: using a first rich concentration during ignition phase for stability, and switching to a second lean concentration after ignition is confirmed to prevent explosions. This dynamic adjustment resolves the contradiction between needing rich mixture for ignition stability and avoiding rich mixture for explosion prevention.
Solution Approach 2:
The patent changes the concentration parameter of the combustible air-gas mixture based on operational phase. The controller modifies the gas concentration parameter from a first value (rich) during ignition to a second value (lean) after ignition confirmation. This parameter change strategy allows the system to optimize ignition reliability while minimizing explosion risk by matching the mixture composition to the current operational requirements.
2Object-affected harmful factors
If a lean combustible air-gas mixture is used to prevent explosion, then safety is improved, but ignition stability deteriorates
Solution Approach 1:
The system dynamically switches between two gas concentration modes: a rich concentration mode during ignition for stability, and a lean concentration mode after ignition for safety. This temporal separation of concentration requirements resolves the contradiction - the system doesn't need to choose between rich and lean, but can use rich when needed for ignition and switch to lean when safety becomes the priority.
Solution Approach 2:
The controller performs preliminary action by confirming ignition success before switching to the lean mixture mode. The system first establishes stable combustion with rich mixture, detects successful ignition, and only then transitions to the safer lean mixture. This preliminary confirmation ensures that safety measures are implemented only when combustion is already established, avoiding ignition failures.
3Reliability
If the gas valve remains open during pre-set ignition safety time, then ignition opportunity is maintained, but combustible air-gas mixture builds up after the burning unit
Solution Approach 1:
The system uses feedback from the flame detector to control the gas valve operation. The flame detector monitors whether ignition has occurred, and this feedback information is used by the controller to adjust gas supply - maintaining open valve during ignition attempt, then closing or modulating the valve based on detected flame presence. This feedback mechanism prevents mixture accumulation by coordinating gas supply with actual combustion status.
Solution Approach 2:
The flame detector acts as an intermediary between the gas supply system and the combustion process. It provides real-time information about flame presence, enabling the controller to mediate gas flow adjustments. This intermediary feedback loop ensures that combustible mixture is supplied only when needed for ignition and is prevented from accumulating when ignition succeeds or fails.
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 solution effectively prevents the accumulation of combustible air-gas mixtures, reducing the risk of explosions and ensuring clean, efficient combustion after ignition.
Implementation Method 1
a second gas valve that is arranged upstream of the first and second gas flow channels
Implementation Method 2
an air-gas mixing unit that is arranged upstream of the burning unit for mixing of air and gas to form the combustible air-gas mixture
Implementation Method 3
a flame detector for sensing presence of a flame in the burning unit
Implementation Method 4
a burning unit for burning a combustible air-gas mixture
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
In an air-gas mixture burning appliance (100) that comprises a burning unit (120) for burning a combustible air-gas mixture (130, 131), a flame detector (150) for sensing presence of a flame (122) in the burning unit (120), an air-gas mixing unit (110) that is arranged upstream of the burning unit (120) for mixing of air and gas to form the combustible air-gas mixture (130, 131), and a gas supply unit (116) that is arranged upstream of the air-gas mixing unit (110), the gas supply unit (116) is adapted to regulating a flow of gas to the air-gas mixing unit (110) such that the combustible air-gas mixture (130, 131) has a variable equivalence ratio between gas and air that is based on whether the flame detector (150) senses the presence of the flame (122) or fails to sense the presence of a flame (122) in the burning unit (120).