Heater Control via Ionization Flame Signal and Actuator Curve
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Solution Overview
Problem
Existing methods for controlling fuel gas-operated heating devices are unreliable at low burner outputs, require high adaptation efforts for different gas types and qualities, and necessitate the use of fuel gas mass sensors, making them inefficient and labor-intensive.
Innovation Solution
A method that uses an ionization measurement of the burner flame to control the air-fuel mixture, with a gas actuator control characteristic stored in a control unit to adjust fuel and air flows based on desired burner outputs, allowing for fuel gas type-independent control across a wide modulation range without the need for a fuel gas mass sensor, and calibrates for characteristic drift over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SCOT method with ionization sensor is used to control burner output, then combustion control is achieved, but control becomes unreliable at low burner outputs due to sharp flame signal drops
Solution Approach 1:
The patent introduces a gas actuator control characteristic curve as an intermediary element that maps gas actuator opening positions to burner outputs. This characteristic curve serves as a mediator between the gas actuator and the ionization sensor, allowing the system to maintain reliable control at low burner outputs by using the pre-recorded relationship between actuator position and burner output rather than relying solely on real-time ionization signal strength.
Solution Approach 2:
The gas actuator control characteristic curve is recorded in advance in the laboratory under controlled conditions. This preliminary action creates a lookup table that stores the relationship between gas actuator opening positions and burner outputs for various gas types and qualities. During actual operation, the system queries this pre-recorded data to determine the appropriate actuator position for a desired burner output, eliminating the need for real-time adaptation and ensuring reliable control across the full modulation range.
2Adaptability or versatility
If SCOT method is used for combustion control, then air supply is regulated based on burner output, but high adaptation effort is required for different gas types and qualities
Solution Approach 1:
The system performs preliminary characterization of different gas types and qualities in the laboratory, recording the gas actuator control characteristic curves for each gas type and quality combination. This advance preparation creates a library of pre-adjusted control parameters that can be directly applied during operation, eliminating the need for real-time adaptation when switching between gas types or qualities.
Solution Approach 2:
The gas actuator control characteristic curve serves multiple functions: it accounts for different gas types (natural gas, LPG), different gas qualities (methane content variations), and different burner outputs simultaneously. By encoding all these variations in the pre-recorded characteristic curve, the system achieves universal adaptability without requiring separate control logic for each gas type or quality scenario.
3Measurement precision
If fan speed is used to determine burner output, then air volume flow is controlled, but burner output can only be determined imprecisely
Solution Approach 1:
The gas actuator control characteristic curve acts as an intermediary that directly relates gas actuator opening positions to burner outputs, bypassing the need to infer burner output from fan speed or other indirect measurements. This characteristic curve provides a direct and precise determination of burner output based on the known relationship between actuator position and fuel flow, recorded during laboratory characterization.
4Measurement precision
If fuel gas mass sensor is used to detect fuel gas properties, then mixture control is achieved, but hardware requirements and monitoring effort increase
Solution Approach 1:
The patent extracts and eliminates the fuel gas mass sensor from the system by using an alternative approach based on gas actuator control characteristic curves. Instead of directly measuring fuel gas properties with a mass sensor, the system uses pre-recorded characteristic data that relates gas actuator opening positions to burner outputs for different gas types and qualities, thereby removing the need for expensive and complex mass sensor hardware.
Solution Approach 2:
The system creates a virtual copy of the fuel gas mass sensor's measurement capability through the gas actuator control characteristic curve. This characteristic curve stores the relationship between gas actuator position and burner output that would otherwise require direct mass sensor measurement, allowing the system to infer fuel gas properties indirectly through the pre-recorded characteristic data without needing the actual sensor hardware.
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 method provides reliable control across varying burner outputs and gas types, reduces monitoring effort and hardware requirements, and maintains precise control by adjusting air and fuel flows proportionally, ensuring clean combustion and adaptability.
Implementation Method 1
a method which uses an ionization measurement method of a burner flame of the heating appliance to control an air-fuel mixture
Implementation Method 2
a fuel gas volume flow controlled by a gas actuator and an air volume flow supplied by a blower are mixed to form a fuel gas-air mixture and supplied to a burner
Data Source
Figure 1
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AI summary
The invention relates to a gas-type-independent method for controlling a fuel gas-operated heating appliance using an ionization measurement method of a burner flame of the heating appliance and a gas actuator control characteristic curve of the gas actuator.