Combustion Chamber Oxygen Sensor Layout for Fast Gas Switching
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Solution Overview
Problem
Existing combustion appliances suffer from high CO emissions, flame loss, flashback, and overheating due to the slow response time of oxygen sensors, making it difficult to transition between different gas families without manual intervention.
Innovation Solution
The oxygen sensor is positioned between the burner and the inlet of the heat exchanger, where the flue gas velocity is high, allowing for rapid detection of changes in air-to-fuel gas ratio, and a data processing device adjusts the combustion parameters based on the sensor's readings to maintain optimal conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the oxygen sensor is placed after the heat exchanger, then the sensor is protected from high temperatures, but the response time increases and water vapor condensation affects measurement accuracy
Solution Approach 1:
The patent introduces a heat-resistant protective structure (ceramic foam filter with specific porosity and thermal properties) as an intermediary between the oxygen sensor and the high-temperature flue gas environment. This mediator allows the sensor to operate in a protected state while still detecting gas composition changes rapidly, resolving the contradiction between temperature protection and response time.
2Loss of time
If the oxygen sensor is placed in the high velocity region between the burner and heat exchanger, then the response time is reduced, but the sensor is exposed to high temperatures and harsh conditions
Solution Approach 1:
The ceramic foam filter serves as a protective intermediary that the flue gas must pass through to reach the sensor. This structure provides thermal protection while maintaining low flow resistance, allowing the sensor to be positioned in the high-velocity region for fast response without direct thermal damage.
Solution Approach 2:
The patent changes the physical parameters of the protective structure (porosity between 80-95%, specific surface area, thermal conductivity) to optimize the balance between thermal protection and gas flow characteristics, enabling fast response time while protecting from high temperatures.
3Measurement precision
If the oxygen sensor measures oxygen value in flue gas after combustion, then combustion control is achieved, but CO emissions increase due to slow response time
Solution Approach 1:
The patent enables preliminary detection of combustion conditions by rapidly measuring oxygen levels in the flue gas. The fast response time allows the control system to adjust the air-to-fuel ratio before incomplete combustion products (CO) are generated, preventing harmful emissions rather than reacting to them after formation.
Solution Approach 2:
The oxygen sensor provides real-time feedback on combustion conditions to the control system. The improved response time enables continuous feedback control that maintains optimal air-to-fuel ratio, preventing CO formation through proactive adjustment rather than reactive correction.
4Stability of the object's composition
If manual intervention is required for gas family transitions, then combustion stability is maintained, but the operation time and complexity increase
Solution Approach 1:
The fast-response oxygen sensor enables automatic feedback control during gas family transitions. The control system continuously monitors oxygen levels and automatically adjusts combustion parameters, eliminating the need for manual intervention while maintaining combustion stability throughout the transition process.
Solution Approach 2:
The rapid sensor response allows the control system to perform preliminary adjustments to combustion parameters before the transition is complete, proactively maintaining stability rather than reacting to instability after it occurs. This enables seamless automatic transitions between gas families.
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 arrangement enables fast transitions between gas families without manual intervention, reducing CO emissions, flame loss, and overheating, while ensuring efficient and stable combustion.
Implementation Method 1
The oxygen sensor can measure the partial oxygen pressure and uses this to determine the oxygen concentration in the gas to be measured
Implementation Method 2
at least one heat exchanger (6) comprising at least one heat exchange region (8), the heat exchange region (8) projecting from the combustion chamber
Implementation Method 3
a burner (4) which is arranged in the combustion chamber (3), wherein a gas and air mixture is combusted by the burner (4) in the combustion chamber (3)
Data Source
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AI summary
The invention relates to a combustion appliance (1) comprising a housing (2) delimiting a combustion chamber (3), a burner (4) which is arranged in the combustion chamber (3), an oxygen sensor (5) for measuring an oxygen value in the combustion chamber (3), in particular a flue gas resulted from combusting an air to fuel gas mixture by the burner (4), and at least one heat exchanger (6) comprising at least one heat exchange region (8a, 8b) of the heat exchanger (6, 6a), the heat exchange region (8) projects from the combustion chamber (3). The combustion appliance is characterized in that the oxygen sensor (5) is arranged between the burner (4) and an inlet (9) of the at least one heat exchange region (8a, 8b) through which the flue gas flows into the at least one heat exchange region (8).