Flame Ionization Sensor for Combustion Control
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Solution Overview
Problem
Existing combustion control systems for gas burners face challenges in maintaining optimal air/gas ratios across varying power outputs and gas types, with limitations in reliability, repeatability, and complexity, especially in modulating burners, and are affected by electrode wear and identification of gas families.
Innovation Solution
A method and system that apply an impulsed periodic electrical voltage signal to a mono-electrode sensor in the flame, measuring response signals to calculate an interpolation function correlating power, air number, and combustion characteristics, allowing for precise control and adaptation to different operating conditions without relying on ionization current measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequency spectrum analysis methods are used to monitor combustion, then combustion parameters can be identified, but the reliability of results is limited and the calculation complexity increases
Solution Approach 1:
The patent extracts only the essential information needed for combustion monitoring by using an electrode to directly measure ionization current, rather than performing complex frequency spectrum analysis on the entire flame signal. This extraction approach obtains the critical combustion parameters while eliminating unnecessary computational complexity.
Solution Approach 2:
The patent replaces the complex computational analysis system (frequency spectrum analysis) with a simpler electrochemical measurement system (ionization current measurement). By substituting the mechanical/computational approach with an electrochemical sensor, the system achieves reliable combustion monitoring with minimal calculation requirements.
2Reliability
If electrode-based ionization measurement is used, then combustion monitoring is achieved, but electrode wear and ageing reduce reliability over time
Solution Approach 1:
The patent incorporates a calibration phase where the system learns the relationship between ionization current and actual combustion parameters under known conditions. This feedback mechanism allows the system to compensate for electrode wear and ageing by continuously adapting to changes in electrode characteristics, thereby maintaining reliable combustion monitoring throughout the electrode's service life.
Solution Approach 2:
The patent performs preliminary calibration measurements during installation or maintenance periods when combustion conditions are known and controllable. This preliminary action establishes a baseline correlation between ionization current and combustion parameters, enabling the system to compensate for future electrode degradation without requiring replacement.
3Manufacturing precision
If combustion control is optimized for specific gas types, then combustion efficiency improves, but the system cannot adapt to different gas families
Solution Approach 1:
The patent creates a universal combustion control system that can handle multiple gas types by establishing a calibration framework that adapts to different gas families. The system uses the same basic measurement principle (ionization current) for all gases but allows calibration parameters to be adjusted based on the specific gas being burned, thereby achieving both efficiency optimization and broad adaptability.
Solution Approach 2:
The patent enables adaptation to different gas types by changing the calibration parameters rather than the fundamental measurement method. The system maintains optimal combustion efficiency for each gas family by adjusting the correlation between ionization current and combustion parameters based on the specific gas characteristics, allowing a single system design to serve multiple applications.
4Measurement precision
If complex calibration procedures are implemented, then measurement accuracy improves, but installation and operation become more difficult
Solution Approach 1:
The patent enables the system to perform its own calibration by using built-in test functions that automatically establish the relationship between ionization current and combustion parameters without requiring external reference equipment or complex manual procedures. This self-calibration capability maintains high measurement precision while significantly simplifying installation and operation for the end user.
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
Ensures reliable and repeatable combustion control across the entire range of power outputs and gas types, simplifies installation and use, and reduces the impact of electrode wear, providing rapid and cost-effective monitoring and control with low voltage potentials.
Implementation Method 1
an analysis of the flame and, in particular, of the ionisation of the gas in the combustion zone of said flame
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A method is described for monitoring and controlling combustion in a burner of a premix combustible gas appliance (1) with fan, of the type comprising a sensor with at least one electrode (E) placed in the flame or in the proximity thereof and suitable for being powered by a voltage generator as well as being connected to an electronic circuit suitable for measuring the resulting potential at the electrode. The method comprises a first phase of acquisition and processing of data from a series of combustion conditions of the burner and a second phase of calculating the air number (λ) in a real operating condition of the burner. The first phase comprises the steps of: identifying a plurality of combustion conditions of the burner (1), applying in each of said conditions in the burner a power (P1, P2, ..., Pn) and applying for each power an air number value (λ1, λ2, ..., λm), said air number expressing the ratio between the quantity of air in the combustion process and the quantity of air for stoichiometric combustion, applying in each of the (n * m) test conditions (Pi, λj) a pulsed electrical voltage signal (S) to the electrode (E) and measuring the trend over time of the resulting electrical signal (S') at the electrode, once the application of the impulsed signal (S) has ceased, said signal (S) applied to the electrode (E) comprising, in the period of the signal (S), a first impulse (N1) with a positive amplitude, followed by a second impulse (N2) with a negative amplitude, identifying, for each of said combustion conditions, the curve of the trend over time of the response signal (S') at the electrode (E), said trend being expressed for each impulse (N1, N2) by an exponential function decreasing over time in absolute terms, calculating for a first section of the curve, relating to the first impulse (N1), as well as for a second curve section relating to the second impulse (N2), the respective first and second time constants (τ1, τ2), characteristic of the exponential trend for the respective first and second curve sections, thus obtaining an interpolation function or correlation table (F), based on the acquired test data, suitable for unequivocally interpolating or correlating at least one significant parameter of the combustion characteristics (power or air number) with the respective time constants of the exponential functions characteristic of the trend in the response signal measured at the electrode, in the combustion process of the burner. The second phase of calculating the air number (λ) in a real operating condition of the burner comprises the steps of: acquiring in said operating condition the electrical response signal measured on the electrode after the application of the impulsed signal, calculating, for said operating condition of the burner, the first and second time constants (τ1, τ2) characteristic of the respective curves sections relating to the trend of the resulting voltage signal at the electrode, following the application of the impulsed signal, calculating the estimated value of the air number (λstim) by using the interpolation function or correlation table (F) which correlates the power (P) and the air number (λ) with the time constants (τ1, τ2) characteristic of the curve relating to the trend in the response signal (S') measured at the electrode (E).