Combustor flame detection method for solid oxide fuel cell system

Abstract

The invention relates to a burner flame detection method for a solid oxide fuel cell system, which comprises the following steps: a temperature signal preprocessing step: collecting an original temperature signal Traw in a burner, filtering and denoising the original temperature signal Traw, and removing signal noise to obtain Tpro; a flame state expert database arrangement step: an input signal is a temperature signal Tpro after signal preprocessing, and an output signal is a temperature signal change rate threshold dTfire and a temperature signal change rate jitter elimination time threshold Tifire corresponding to the temperature signal; and an ignition temperature comparison step: the Tfire is the ignition temperature of the fuel, and if the Tpro is greater than the Tfire, the fuel is judged to be in a combustion state. According to the invention, the temperature signal of the temperature sensor arranged in the burner can be processed, and the actual flame state in the burner at present can be accurately judged through a flame detection algorithm.

Description

Technical Field

[0001] The invention relates to the technical field of industrial power generation, and in particular to a burner flame detection method for a solid oxide fuel cell system. Background Art

[0002] Solid oxide fuel cell (SOFC) is a power generation device that operates in a high-temperature environment and generates electricity through chemical reactions between fuel and oxidant. It has the advantages of high power generation efficiency, low carbon emissions, and strong fuel adaptability. It has broad application prospects in large-scale power generation and reducing carbon emissions.

[0003] The rated operating temperature of the solid oxide fuel cell system (SOFC) is usually above 700°C, so it is necessary to first heat up the stack, the site of the core chemical reaction in the SOFC. Since the internal structure of the stack is very easy to be damaged when the temperature changes rapidly, it is necessary to control the rate of temperature change to ensure that the temperature of the stack does not change suddenly. Usually, a heating device is configured in the SOFC system to control the temperature of the system. There are two common heating methods: electric heaters and burners. Among them, the control method of electric heaters is simple, but the power consumption is large, resulting in a waste of electricity. The burner has the advantages of high heat source temperature and low fuel consumption, but the burner has problems such as unstable flame combustion, inaccurate flame state detection and judgment, and difficult control of the heating rate.

[0004] If the current burner flame status cannot be accurately determined, many technical problems will arise: for example, if it is not determined that the fuel inside the burner has been ignited, the ignition operation will be repeated frequently; for example, if it is not determined that the burner has been extinguished, the system temperature will be reduced and the concentration of unburned fuel will accumulate to a high level, posing a safety hazard. Summary of the invention

[0005] The purpose of the present invention is to provide a burner flame detection method for a solid oxide fuel cell system, which can accurately determine the actual flame state inside the current burner by processing the temperature signal of a temperature sensor built into the burner through a flame detection algorithm.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A burner flame detection method for a solid oxide fuel cell system comprises the following steps:

[0008] Temperature signal preprocessing step: collect the original temperature signal T_raw inside the burner, filter and reduce noise on the original temperature signal T_raw, remove signal noise, and obtain T_pro;

[0009] Flame state expert database sorting steps: its input signal is the temperature signal T_pro after signal preprocessing, and its output signal is the temperature signal change rate threshold dT_fire and the temperature signal change rate debounce time threshold Ti_fire corresponding to the temperature signal;

[0010] Ignition temperature comparison steps:

[0011] T_fire is the ignition temperature of the fuel. If T_pro is greater than T_fire, the fuel is determined to be in a burning state;

[0012] If T_pro is less than or equal to T_fire, the temperature signal change rate calculation step is performed: T_pro is re-sampled at a frequency of 1 Hz, and the current temperature signal change rate dT with obvious changes is calculated by reducing the sampling frequency;

[0013] Temperature signal change rate comparison steps:

[0014] If the current temperature signal change rate dT is greater than the temperature signal change rate threshold dT_fire corresponding to the temperature signal, and the change duration Ti corresponding to the current temperature signal change rate dT is greater than the temperature signal change rate debounce time threshold Ti_fire corresponding to the temperature signal, then it is determined that the fuel is in a combustion state; otherwise, the temperature signal change rate determination step for the next time period is performed;

[0015] If the current temperature signal change rate dT is less than or equal to the temperature signal change rate threshold dT_fire corresponding to the temperature signal, compare the current temperature signal change rate dT with -dT_fire. If the current temperature signal change rate dT is less than -dT_fire, and the change duration Ti corresponding to the current temperature signal change rate dT is greater than the temperature signal change rate de-jitter time threshold Ti_fire corresponding to the temperature signal, it is determined that the fuel is not in a combustion state; otherwise, perform the temperature signal change rate determination step for the next time period.

[0016] Specifically, sensors are placed at low, middle and high positions inside the burner to measure the raw temperature signal T_raw.

[0017] Specifically, a signal preprocessing module is used to filter and reduce noise on the original temperature signal T_raw, remove signal noise, and obtain T_pro.

[0018] Specifically, a threshold judgment module is used to compare the previous temperature signal change rate dT with the temperature signal change rate threshold dT_fire corresponding to the temperature signal.

[0019] Specifically, a de-bouncing time judgment module is used to compare the change duration Ti corresponding to the current temperature signal change rate dT with the temperature signal change rate de-bouncing time threshold Ti_fire corresponding to the temperature signal.

[0020] Specifically, the flame state expert database is an empirical database obtained by sorting out experimental data of fuel combustion. Through the expert database, the temperature signal change rate threshold dT_fire and the temperature signal change rate debounce time threshold Ti_fire under different temperature conditions are output.

[0021] Specifically, the rated operating temperature of the burner is greater than 700 degrees Celsius.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The temperature-based burner flame detection method has the advantage of simple hardware equipment. All hardware parts can be installed by placing a temperature sensor inside the burner, and no other complex detection equipment is required. The expert database is enriched with preliminary test data, and the rate threshold and debounce time under different temperature conditions are calibrated. By calculating the temperature change rate and combining the rate threshold and debounce time judgment of the expert database, the flame state can be accurately judged. It is convenient for rapid manual intervention when unexpected conditions occur in the burner, ensuring the stable operation of the system.

[0024] When the temperature change rate is calculated, a de-bouncing time judgment is required. Only when the calculated temperature rate exceeds the threshold and lasts longer than the rate de-bouncing time, the calculated temperature rate is considered to be true, thereby eliminating the impact of sudden jitter of the temperature signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 It is a flowchart of the present invention. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0028] See Figure 1, a burner flame detection method for a solid oxide fuel cell system, comprising the following steps:

[0029] Temperature signal preprocessing step: collect the original temperature signal T_raw inside the burner, filter and reduce noise on the original temperature signal T_raw, remove signal noise, and obtain T_pro;

[0030] Flame state expert database sorting steps: its input signal is the temperature signal T_pro after signal preprocessing, and its output signal is the temperature signal change rate threshold dT_fire and the temperature signal change rate debounce time threshold Ti_fire corresponding to the temperature signal;

[0031] Ignition temperature comparison steps:

[0032] T_fire is the ignition temperature of the fuel. If T_pro is greater than T_fire, the fuel is determined to be in a burning state;

[0033] If T_pro is less than or equal to T_fire, the temperature signal change rate calculation step is performed: T_pro is re-sampled at a frequency of 1 Hz, and the current temperature signal change rate dT with obvious changes is calculated by reducing the sampling frequency;

[0034] Temperature signal change rate comparison steps:

[0035] If the current temperature signal change rate dT is greater than the temperature signal change rate threshold dT_fire corresponding to the temperature signal, and the change duration Ti corresponding to the current temperature signal change rate dT is greater than the temperature signal change rate debounce time threshold Ti_fire corresponding to the temperature signal, then it is determined that the fuel is in a combustion state; otherwise, the temperature signal change rate determination step for the next time period is performed;

[0036] If the current temperature signal change rate dT is less than or equal to the temperature signal change rate threshold dT_fire corresponding to the temperature signal, compare the current temperature signal change rate dT with -dT_fire. If the current temperature signal change rate dT is less than -dT_fire, and the change duration Ti corresponding to the current temperature signal change rate dT is greater than the temperature signal change rate de-jitter time threshold Ti_fire corresponding to the temperature signal, it is determined that the fuel is not in a combustion state; otherwise, perform the temperature signal change rate determination step for the next time period.

[0037] Specifically, sensors are placed at low, middle and high positions inside the burner to measure the raw temperature signal T_raw.

[0038] Specifically, a signal preprocessing module is used to filter and reduce noise on the original temperature signal T_raw, remove signal noise, and obtain T_pro.

[0039] Specifically, a threshold judgment module is used to compare the previous temperature signal change rate dT with the temperature signal change rate threshold dT_fire corresponding to the temperature signal.

[0040] Specifically, a de-bouncing time judgment module is used to compare the change duration Ti corresponding to the current temperature signal change rate dT with the temperature signal change rate de-bouncing time threshold Ti_fire corresponding to the temperature signal.

[0041] Specifically, the flame state expert database is an empirical database obtained by sorting out experimental data of fuel combustion. Through the expert database, the temperature signal change rate threshold dT_fire and the temperature signal change rate debounce time threshold Ti_fire under different temperature conditions are output.

[0042] Specifically, the rated operating temperature of the burner is greater than 700 degrees Celsius.

[0043] The working principle of the present invention is as follows:

[0044] The algorithm flow chart of a temperature-based burner flame detection method for a solid oxide fuel cell system is as follows: Figure 1 First, the original temperature signal T_raw inside the burner is collected. In order to ensure that the temperature signal can correctly reflect the temperature inside the burner, sensors are placed at least at low, medium and high positions inside the burner. Here, only the processing of one temperature signal is described.

[0045] After acquiring the original temperature signal, the signal is preprocessed to obtain T_pro. The signal preprocessing module performs low-pass filtering on the original signal to avoid noise interference on the signal. The sampling frequency of the temperature signal is usually 100Hz or higher, but the temperature type signal itself is not a mutation type signal, so the sampled temperature signal is easily interfered by noise. Through temperature signal preprocessing, the signal is filtered and denoised, and the signal noise is removed to avoid signal noise from interfering with the subsequent temperature rate calculation.

[0046] The pre-processed signal is input into the expert database. The expert database is the basis for judging the flame state at different temperatures obtained from the test data. Through the expert database, the threshold dT_fire for judging the temperature rate and the threshold Ti_fire for the debounce time under different temperature conditions are output, and the temperature rate is dynamically judged, avoiding the problem of inaccurate judgment caused by fixed threshold judgment.

[0047] The pre-processed signal is initially judged. When the temperature is greater than the threshold value T_fire, it is considered that there is a flame inside the current burner. The T_fire value is defined according to the ignition point of the fuel. If the current internal temperature of the burner is greater than the ignition point of the fuel, it is considered that the fuel must be in a burning state.

[0048] If the current temperature is less than T_fire, the temperature signal is calculated for rate of change. Rate calculation includes first reducing the sampling frequency of the temperature signal, and then calculating the temperature signal change value. It mainly resamples the preprocessed temperature signal at a frequency of 1Hz. Because the temperature signal changes slowly, a temperature signal with obvious changes can be obtained by reducing the sampling frequency. After reducing the sampling frequency, the rate of change of the signal is calculated, and finally the temperature signal change rate dT is obtained.

[0049] After calculating the current temperature change rate, enter the threshold judgment module. Compare the actual temperature change rate with the rate threshold dT_fire at the current temperature output by the expert database. If it is greater than the threshold, the debouncing module timer is triggered to enter the debouncing time judgment module. Only when the temperature rate is greater than the threshold and the duration is greater than the debouncing time threshold Ti_fire, the condition is met at the same time, it is considered that there is a flame inside the current burner, and the output signal 1 is output.

[0050] If the current temperature rate is less than the threshold dT_fire, it needs to be further judged whether it is less than -dT_fire to determine whether the burner is extinguished. If the current temperature rate dT is less than -dT_fire, the debounce module timer is triggered to enter the debounce time judgment module. Only when the temperature rate is less than the threshold and the duration is greater than the debounce time threshold Ti_fire, it is considered that there is no flame in the current combustion and the output signal is 0.

[0051] When the temperature change rate does not meet the above two conditions, it is considered that the flame state has not changed, and the output is the previous flame detection value.

[0052] When the temperature change rate is calculated, a de-bouncing time judgment is required. Only when the calculated temperature rate exceeds the threshold and lasts longer than the rate de-bouncing time, the calculated temperature rate is considered to be true, thereby eliminating the impact of sudden jitter of the temperature signal.

[0053] Only when the calculated temperature change rate exceeds the threshold and lasts longer than the debounce time, is the current combustion state considered to have changed, depending on the direction of the temperature rate change. If the rate is positive and greater than the threshold, it is considered to have changed from a no-flame state to a flame state; if the rate is negative and less than the threshold, it is considered to have changed from a flame state to a no-flame state.

[0054] The beneficial effects of the present invention are as follows:

[0055] The temperature-based burner flame detection method has the advantage of simple hardware equipment. All hardware parts can be installed by placing a temperature sensor inside the burner, and no other complex detection equipment is required. The expert database is enriched with preliminary test data, and the rate threshold and debounce time under different temperature conditions are calibrated. By calculating the temperature change rate and combining the rate threshold and debounce time judgment of the expert database, the flame state can be accurately judged. It is convenient for rapid manual intervention when unexpected conditions occur in the burner, ensuring the stable operation of the system.

[0056] When the temperature change rate is calculated, a de-bouncing time judgment is required. Only when the calculated temperature rate exceeds the threshold and lasts longer than the rate de-bouncing time, the calculated temperature rate is considered to be true, thereby eliminating the impact of sudden jitter of the temperature signal.

[0057] Only when the calculated temperature change rate exceeds the threshold and lasts longer than the debounce time, is the current combustion state considered to have changed, depending on the direction of the temperature rate change. If the rate is positive and greater than the threshold, it is considered to have changed from a no-flame state to a flame state; if the rate is negative and less than the threshold, it is considered to have changed from a flame state to a no-flame state.

[0058] The above are only preferred embodiments of the present invention, and are not intended to limit the present invention in any form. Although the present invention has been disclosed as above in the form of preferred embodiments, it is not intended to limit the present invention. Any technical personnel in the field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A burner flame detection method for a solid oxide fuel cell system, characterized in that: The following steps are involved: Temperature signal preprocessing step: collect the original temperature signal T_raw inside the burner, filter and reduce noise on the original temperature signal T_raw, remove signal noise, and obtain T_pro; Flame state expert database sorting steps: its input signal is the temperature signal T_pro after signal preprocessing, and its output signal is the temperature signal change rate threshold dT_fire and the temperature signal change rate debounce time threshold Ti_fire corresponding to the temperature signal; Ignition temperature comparison steps: T_fire is the ignition temperature of the fuel. If T_pro is greater than T_fire, the fuel is determined to be in a burning state; If T_pro is less than or equal to T_fire, the temperature signal change rate calculation step is performed: T_pro is re-sampled at a frequency of 1 Hz, and the current temperature signal change rate dT with obvious changes is calculated by reducing the sampling frequency; Temperature signal change rate comparison steps: If the current temperature signal change rate dT is greater than the temperature signal change rate threshold dT_fire corresponding to the temperature signal, and the change duration Ti corresponding to the current temperature signal change rate dT is greater than the temperature signal change rate debounce time threshold Ti_fire corresponding to the temperature signal, then it is determined that the fuel is in a combustion state; otherwise, the temperature signal change rate determination step for the next time period is performed; If the current temperature signal change rate dT is less than or equal to the temperature signal change rate threshold dT_fire corresponding to the temperature signal, compare the current temperature signal change rate dT with -dT_fire. If the current temperature signal change rate dT is less than -dT_fire, and the change duration Ti corresponding to the current temperature signal change rate dT is greater than the temperature signal change rate de-jitter time threshold Ti_fire corresponding to the temperature signal, it is determined that the fuel is not in a combustion state; otherwise, perform the temperature signal change rate determination step for the next time period.

2. The burner flame detection method for a solid oxide fuel cell system according to claim 1, characterized in that: Sensors are placed at low, middle and high positions inside the burner to measure the raw temperature signal T_raw.

3. The burner flame detection method for a solid oxide fuel cell system according to claim 1, characterized in that: The signal preprocessing module is used to filter and reduce noise on the original temperature signal T_raw, remove signal noise, and obtain T_pro.

4. The burner flame detection method for a solid oxide fuel cell system according to claim 1, characterized in that: The threshold judgment module is used to compare the previous temperature signal change rate dT with the temperature signal change rate threshold dT_fire corresponding to the temperature signal.

5. The burner flame detection method for a solid oxide fuel cell system according to claim 1, characterized in that: The de-jitter time judgment module is used to compare the change duration Ti corresponding to the current temperature signal change rate dT with the temperature signal change rate de-jitter time threshold Ti_fire corresponding to the temperature signal.

6. The burner flame detection method for a solid oxide fuel cell system according to claim 1, characterized in that: The flame state expert database is an empirical database obtained based on the test data of fuel combustion. Through the expert database, the temperature signal change rate threshold dT_fire and the temperature signal change rate debounce time threshold Ti_fire under different temperature conditions are output.

7. The burner flame detection method for a solid oxide fuel cell system according to claim 1, characterized in that: The rated operating temperature of the burner is greater than 700 degrees Celsius.

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