Method for evaluating in-furnace multi-element combustion working condition of opposed firing boiler

Abstract

The embodiment of the invention provides an in-furnace multi-element combustion working condition evaluation method for an opposed firing boiler, which comprises the following steps: acquiring the running oxygen amount in a boiler hearth and the actual value of the concentration of carbon monoxide in flue gas at an outlet of a denitration device of the boiler, comparing the running oxygen amount with the designed oxygen amount, and determining the actual value of the concentration of carbon monoxide in the flue gas at the outlet of the denitration device; and comparing the actual value of the carbon monoxide concentration with the target value of the carbon monoxide concentration, and evaluating the overall combustion condition of the boiler. Acquiring an oxygen concentration detection value, a carbon monoxide concentration detection value and a flue gas temperature value in flue gas of each combustor of a hearth, comparing the oxygen concentration detection value with an oxygen concentration early warning value, comparing the carbon monoxide concentration detection value with a carbon monoxide concentration early warning value, and comparing the temperature detection value with a temperature early warning value; evaluating the local combustion condition of the boiler; and obtaining hearth local negative pressure detection values and flame detection signals at all the combustors, and determining combustion working conditions of all the combustors in the hearth based on comparison of the negative pressure detection values and the flame detection signals with early warning values.

Description

Technical Field

[0001] The embodiments of the present disclosure belong to the technical field of boilers, and specifically relate to a method for evaluating multi-combustion conditions in a counter-firing boiler. Background Art

[0002] The counter-firing boiler is one of the conventional furnace types in thermal power plants. The burners are arranged in multiple layers on the front and rear walls of the furnace water-cooled wall. The pulverized coal airflow is ejected from the front and rear wall burners to form a mainly upward airflow.

[0003] Since opposed-firing boilers mostly use swirl burners, and the ignition effect between burners is poor, the combustion method is "independent torch", and the combustion efficiency of each burner is determined by its own coal powder concentration and air distribution method.

[0004] However, currently, power plant boilers usually monitor the overall combustion status of the furnace through oxygen measurement points arranged in the flue at the rear of the boiler, and cannot accurately evaluate the overall and local combustion conditions of the boiler in a timely manner. As a result, problems such as poor combustion efficiency of some burners are often not discovered in time, resulting in a strong local reducing atmosphere in the boiler furnace, which in turn causes problems such as high-temperature corrosion of the boiler water-cooled wall. Summary of the invention

[0005] The embodiments of the present disclosure aim to solve at least one of the technical problems existing in the prior art and provide a method for evaluating the multi-combustion conditions in a counter-combustion boiler furnace.

[0006] One aspect of an embodiment of the present disclosure provides a method for evaluating a multi-element combustion condition in a counter-firing boiler furnace, comprising:

[0007] Obtain the operating oxygen content in the boiler furnace and the actual value of the carbon monoxide concentration in the flue gas at the outlet of the boiler denitrification device;

[0008] Comparing the operating oxygen amount with the designed oxygen amount, and comparing the actual carbon monoxide concentration with the target carbon monoxide concentration;

[0009] According to the comparison result of the operating oxygen amount and the designed oxygen amount, and the comparison result of the actual carbon monoxide concentration and the target carbon monoxide concentration, the overall combustion condition of the boiler is evaluated;

[0010] The working condition assessment method further includes:

[0011] Obtaining oxygen concentration detection values ​​and carbon monoxide concentration detection values ​​in the flue gas above each burner in the furnace;

[0012] Comparing the oxygen concentration detection value with the oxygen concentration warning value, and comparing the carbon monoxide concentration detection value with the carbon monoxide concentration warning value;

[0013] According to the comparison result of the oxygen concentration detection value and the oxygen concentration warning value, and the comparison result of the carbon monoxide concentration detection value and the carbon monoxide concentration warning value, evaluating the local combustion condition of the boiler;

[0014] The working condition assessment method further includes:

[0015] Obtain the temperature detection value of the flue gas at each burner in the furnace;

[0016] Comparing the temperature detection value with the temperature warning value;

[0017] According to the comparison result of the temperature detection value and the temperature warning value, the comparison result of the oxygen concentration detection value and the oxygen concentration warning value, and the comparison result of the carbon monoxide concentration detection value and the carbon monoxide concentration warning value, the partial burnout condition of the boiler is evaluated;

[0018] The working condition assessment method further includes:

[0019] Obtaining the furnace local negative pressure detection value and flame detection signal at each burner;

[0020] The combustion conditions of each burner in the furnace are determined based on the comparison of the negative pressure detection value and the warning values ​​respectively corresponding to the flame detection signal.

[0021] In some embodiments, based on the comparison result that the operating oxygen amount is lower than the designed oxygen amount, and the actual carbon monoxide concentration is higher than the target carbon monoxide concentration, it is judged that the overall combustion efficiency of the boiler is lower than the expected combustion efficiency.

[0022] In some embodiments, based on a comparison result that the oxygen concentration detection value is lower than the oxygen concentration warning value, and the carbon monoxide concentration detection value is higher than the carbon monoxide concentration warning value, it is determined that the combustion efficiency of the burner is lower than the expected combustion efficiency.

[0023] In some embodiments, based on the comparison result that the temperature detection value is higher than the temperature warning value, the oxygen concentration detection value is lower than the oxygen concentration warning value, and the carbon monoxide concentration detection value is higher than the carbon monoxide concentration warning value, it is judged that the burnout rate of the burner is lower than the expected burnout rate.

[0024] In some embodiments, the combustion operating conditions of the burner include a combustion stability operating condition.

[0025] Characterized in that, the negative pressure detection value at each burner in the furnace is obtained;

[0026] Comparing the negative pressure detection value with the negative pressure warning value;

[0027] According to the comparison result of the negative pressure detection value and the negative pressure warning value, the combustion stability working condition of each burner is evaluated.

[0028] In some embodiments, the evaluating the combustion stability condition of each of the burners according to the comparison result of the negative pressure detection value and the negative pressure warning value includes:

[0029] Based on the comparison result that the fluctuation of the negative pressure detection value is greater than the negative pressure warning value, it is determined that the combustion of the burner is unstable and there is a risk of fire extinguishing.

[0030] In some embodiments, the combustion operating conditions of the burner include a combustion stability operating condition.

[0031] It is characterized in that

[0032] Obtaining flame detection signals of the flames of each burner in the furnace;

[0033] Comparing the flame detection signal with the flame warning value;

[0034] The combustion stability condition of each of the burners is evaluated based on the comparison result of the flame detection value and the flame warning value.

[0035] In some embodiments, the evaluating the combustion stability condition of each of the burners according to the comparison result of the flame detection value and the flame warning value includes:

[0036] Based on the comparison result that the fluctuation of the flame detection value is greater than the flame warning value, it is determined that the combustion of the burner is unstable and there is a risk of fire extinguishing.

[0037] The beneficial effects of the embodiments of the present disclosure include:

[0038] In the present invention, based on the collected operating oxygen content, carbon monoxide, oxygen concentration, temperature and negative pressure data, the combustion conditions in the furnace can be evaluated in multiple dimensions, thereby evaluating the local or overall combustion conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a flow chart of a method for evaluating multi-element combustion conditions in a counter-firing boiler furnace according to the first embodiment of the present disclosure;

[0040] Figure 2 It is a flow chart of a method for evaluating multi-element combustion conditions in a counter-firing boiler furnace according to the second embodiment of the present disclosure;

[0041] Figure 3 It is a flow chart of a method for evaluating multi-element combustion conditions in a counter-firing boiler furnace according to the third embodiment of the present disclosure;

[0042] Figure 4 It is a flow chart of a method for evaluating a multi-element combustion condition in a counter-firing boiler furnace according to a fourth embodiment of the present disclosure;

[0043] Figure 5 It is a schematic flow chart of a method for evaluating multi-combustion conditions in a counter-firing boiler furnace according to the fifth embodiment of the present disclosure. DETAILED DESCRIPTION

[0044] In order to enable those skilled in the art to better understand the technical solution of the present disclosure, the present disclosure is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0045] The following is a further detailed description of the implementation methods of the present application in conjunction with the accompanying drawings and examples. The detailed descriptions and drawings of the following examples are used to illustrate the principles of the present application, but cannot be used to limit the scope of the present application, that is, the present application is not limited to the described embodiments. In the description of the present application, it should be noted that, unless otherwise specified, the meaning of "multiple" is more than two; the orientation or position relationship indicated by the terms "upper", "lower", "left", "right", "inside", "outside", etc. is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. "Vertical" is not vertical in the strict sense, but within the error tolerance range. "Parallel" is not parallel in the strict sense, but within the error tolerance range.

[0046] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0047] like Figure 1 As shown, a method for evaluating the multi-element combustion conditions in a counter-firing boiler furnace comprises:

[0048] S101. Obtain the operating oxygen content in the boiler furnace and the actual value of the carbon monoxide concentration in the flue gas at the outlet of the boiler denitrification device.

[0049] Specifically, the operating oxygen amount can be detected by an oxygen sensor installed in the furnace, that is, the operating oxygen amount is directly obtained by measuring the oxygen concentration in the flue gas. In addition, the operating oxygen amount can also be obtained by a flue gas analyzer, which includes but is not limited to a portable flue gas analyzer or a fixed flue gas analyzer.

[0050] S102: Compare the operating oxygen amount with the designed oxygen amount, and compare the actual carbon monoxide concentration with the target carbon monoxide concentration.

[0051] S103. Evaluate the overall combustion condition of the boiler based on the comparison results of the operating oxygen content and the designed oxygen content, and the comparison results of the actual carbon monoxide concentration and the target carbon monoxide concentration.

[0052] In the present invention, by obtaining the boiler operating oxygen content and the carbon monoxide concentration data in the denitrification outlet flue gas, and comparing them with the designed oxygen content and carbon monoxide target values ​​respectively, the overall combustion condition in the furnace can be evaluated.

[0053] In some embodiments, the overall combustion condition in the boiler includes the overall combustion efficiency of the boiler. Based on the comparison result that the operating oxygen amount is lower than the designed oxygen amount and the actual carbon monoxide concentration is higher than the target carbon monoxide concentration, it is determined that the overall combustion efficiency of the boiler is lower than the expected combustion efficiency.

[0054] refer to Figure 2 In some embodiments, the evaluation method further comprises:

[0055] S201, obtaining oxygen concentration detection values ​​and carbon monoxide concentration detection values ​​in the flue gas above each burner in the furnace.

[0056] Specifically, the oxygen concentration detection value can be detected by a number of oxygen sensors installed in the furnace, that is, the oxygen concentration detection value can be directly obtained by measuring the oxygen concentration in the flue gas above each burner, and the carbon monoxide concentration detection value can be detected by a carbon monoxide sensor installed in the furnace. In addition, the oxygen concentration detection value and the carbon monoxide concentration detection value can also be obtained through a flue gas analyzer, which includes but is not limited to a portable flue gas analyzer or a fixed flue gas analyzer.

[0057] S202: Compare the oxygen concentration detection value with the oxygen concentration warning value, and compare the carbon monoxide concentration detection value with the carbon monoxide concentration warning value.

[0058] S203, based on the comparison results of the oxygen concentration detection value and the oxygen concentration warning value, and the comparison results of the carbon monoxide concentration detection value and the carbon monoxide concentration warning value, evaluate the local combustion condition of the boiler. It can be understood that the local combustion condition of the boiler is the combustion condition of the local burner in the horizontal direction in the furnace.

[0059] In the present invention, the local combustion condition of the furnace is evaluated by extracting the flue gas from the upper outlet of the burner and detecting the concentration information of gases such as oxygen and carbon monoxide in the flue gas.

[0060] In some embodiments, based on the comparison result that the oxygen concentration detection value is lower than the oxygen concentration warning value, and the carbon monoxide concentration detection value is higher than the carbon monoxide concentration warning value, it is judged that the combustion efficiency of the burner is lower than the expected combustion efficiency.

[0061] refer to Figure 3 In some embodiments, the evaluation method further comprises:

[0062] S301, obtaining the temperature detection value of the flue gas at each burner in the furnace.

[0063] Specifically, the temperature detection value can be detected by a temperature sensor installed at the burner.

[0064] S302: Compare the temperature detection value with the temperature warning value.

[0065] S303. Evaluate the partial burnout condition of the boiler based on the comparison results of the temperature detection value and the temperature warning value, the comparison results of the oxygen concentration detection value and the oxygen concentration warning value, and the comparison results of the carbon monoxide concentration detection value and the carbon monoxide concentration warning value.

[0066] In the present invention, the burner outlet temperature information is obtained and comprehensively analyzed with the oxygen concentration and carbon monoxide concentration information at the burner to evaluate the local combustion conditions of the furnace.

[0067] In some embodiments, based on the comparison results that the temperature detection value is higher than the temperature warning value, the oxygen concentration detection value is lower than the oxygen concentration warning value, and the carbon monoxide concentration detection value is higher than the carbon monoxide concentration warning value, it is judged that the burnout rate of the burner is lower than the expected burnout rate.

[0068] In some embodiments, a furnace local negative pressure detection value and a flame detection signal are obtained at each burner.

[0069] The combustion conditions of each burner in the furnace are determined based on the comparison of the negative pressure detection value and the flame detection signal corresponding to the warning values.

[0070] refer to Figure 4 In some embodiments, the combustion condition of the burner includes a combustion stability condition, including:

[0071] S401, obtaining negative pressure detection values ​​at each burner in the furnace.

[0072] Specifically, the negative pressure detection value can be detected by a negative pressure detection device installed at each burner, and the negative pressure detection device includes a negative pressure sensor.

[0073] S402: Compare the negative pressure detection value with the negative pressure warning value.

[0074] S403. Evaluate the combustion stability working condition of each burner according to the comparison result of the negative pressure detection value and the negative pressure warning value.

[0075] In the present invention, by detecting the negative pressure detection value at the burner and comparing it with the negative pressure warning value, the independent flare combustion stability working condition of each burner can be evaluated.

[0076] In some embodiments, step S403 evaluates the combustion stability condition of each burner based on the comparison result of the negative pressure detection value and the negative pressure warning value, including: judging that the combustion of the burner is unstable and there is a risk of fire extinguishing based on the comparison result that the fluctuation of the negative pressure detection value is greater than the negative pressure warning value.

[0077] refer to Figure 5 In some embodiments, the combustion condition of the burner includes a combustion stability condition, including:

[0078] S501, obtaining flame detection signals of the flames of each burner in the furnace.

[0079] Specifically, the flame detection signal includes a light intensity signal or a radiation signal. The flame detection signal is measured by a flame detection device, which includes an ultraviolet sensor, an infrared sensor or a visible light sensor for detecting the flame detection signal.

[0080] S502: Compare the flame detection signal with the flame warning value.

[0081] S503. Evaluate the combustion stability condition of each burner according to the comparison result of the flame detection value and the flame warning value.

[0082] In the present invention, by detecting the flame detection signal at the burner and comparing it with the flame warning value, the combustion stability working condition of the independent torch of each burner can be evaluated.

[0083] In some embodiments, step S503 evaluates the combustion stability condition of each burner based on the comparison result of the flame detection value and the flame warning value, including: judging that the combustion of the burner is unstable and there is a risk of fire extinguishing based on the comparison result that the flame detection value fluctuation is greater than the flame warning value.

[0084] In summary, the evaluation method of the present invention can more truly and comprehensively reflect the combustion conditions of the boiler as a whole and the local combustion conditions of each burner, and realize accurate evaluation of the multi-element combustion conditions of the furnace.

[0085] A specific example provided by the present invention includes:

[0086] The unit boiler of the power plant adopts an opposed combustion boiler. The front and rear walls of the opposed combustion boiler are respectively arranged with three layers of burners, and each layer is arranged with four burners.

[0087] The burners are all operating under rated load, and the operating oxygen content in the flue gas obtained by the flue gas analyzer is 1.8%, and the actual value of the carbon monoxide concentration in the flue gas at the denitrification outlet is 500ppm. Among them, the boiler operating oxygen content is 2% lower than the designed oxygen content, and the actual value of the carbon monoxide concentration in the flue gas at the denitrification outlet is higher than the target value of carbon monoxide concentration of 100ppm. Based on the above comparative analysis, it is judged that the overall combustion condition of the boiler furnace deviates, and the overall combustion efficiency of the boiler is lower than the expected combustion efficiency.

[0088] Four flue gas sampling tubes A1 / A2 / A3 / A4 are arranged above the front wall of the upper part of the furnace, and four flue gas sampling tubes B1 / B2 / B3 / B4 are arranged above the rear wall to extract the flue gas at the upper outlet of the furnace. After the flue gas is filtered through dust removal, the flue gas is analyzed online by the flue gas analyzer to obtain the gas concentration information such as oxygen and carbon monoxide in the flue gas, which is used to evaluate the local combustion conditions of the furnace, specifically:

[0089] A1 / A2 / A3 / A4 flue gas sampling tubes are arranged directly above the No. 1, No. 2, No. 3 and No. 4 burners on each layer of the front wall. B1 / B2 / B3 / B4 flue gas sampling tubes are arranged directly above the No. 1, No. 2, No. 3 and No. 4 burners on each layer of the rear wall.

[0090] When the oxygen concentration detection value in the flue gas extracted by the A1 flue gas sampling tube is 2%, and the carbon monoxide concentration detection value is 800ppm, wherein the oxygen concentration detection value of 2% is lower than the oxygen concentration warning value of 2.5%, and the carbon monoxide concentration detection value of 800ppm is higher than the carbon monoxide concentration warning value of 100ppm, then the local combustion condition deviation of burner No. 1 on the front wall directly below the A1 flue gas sampling tube, that is, the combustion efficiency of the burner is lower than the expected combustion efficiency.

[0091] The furnace outlet temperature information is obtained by arranging several flue gas temperature measuring points on the front and rear walls of the upper part of the furnace. The local combustion conditions of the furnace are evaluated by comprehensive analysis with the oxygen concentration and carbon monoxide concentration obtained by the A1 burner. Specifically:

[0092] The A1 / A2 / A3 / A4 flue gas temperature measuring points are arranged directly above the No. 1, No. 2, No. 3 and No. 4 burners on each layer of the front wall. The B1 / B2 / B3 / B4 flue gas temperature measuring points are arranged directly above the No. 1, No. 2, No. 3 and No. 4 burners on each layer of the rear wall, and the positions of the flue gas temperature measuring points are close to the flue gas sampling tubes arranged above.

[0093] When the temperature detection value of the A1 flue gas temperature measuring point is 1350℃, the oxygen concentration detection value of the flue gas extracted from the flue gas sampling tube at A1 is 2%, and the carbon monoxide concentration detection value is 800ppm. Since the oxygen concentration detection value of 2% is lower than the oxygen concentration warning value of 2.5%, the carbon monoxide concentration detection value of 800ppm is higher than the carbon monoxide concentration warning value of 100ppm, and the flue gas temperature detection value is higher than the flue gas temperature warning value of 1300℃, it means that the coal powder concentration of the burner corresponding to the A1 flue gas temperature measuring point is high and the burnout rate is low, that is, lower than the expected burnout rate.

[0094] The combustion conditions of each burner are evaluated by the furnace negative pressure measuring device and flame detection device arranged directly above each burner, specifically:

[0095] The A1 / A2 / A3 / A4 furnace negative pressure measuring devices and the A1 / A2 / A3 / A4 flame detection devices are arranged 100mm above the No. 1, No. 2, No. 3 and No. 4 burners on the bottom layer A of the front wall respectively. The arrangement of combustion on other layers is similar.

[0096] When the fluctuation of the negative pressure detection values ​​of the A1 furnace negative pressure measuring device and the A1 flame detection device is greater than the negative pressure warning value, and the fluctuation of the flame detection signal is greater than the flame warning value (such as the fluctuation amplitude is greater than 50% within 5s), the burner directly below the A1 furnace negative pressure measuring device and the A1 flame detection device is unstable and there is a risk of fire extinguishing.

[0097] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present disclosure, but the present disclosure is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and substance of the present disclosure, and these modifications and improvements are also considered to be within the scope of protection of the present disclosure.

Claims

1. A method for evaluating the multi-element combustion conditions in a counter-firing boiler, characterized in that: include: Obtain the operating oxygen content in the boiler furnace and the actual value of the carbon monoxide concentration in the flue gas at the outlet of the boiler denitrification device; Comparing the operating oxygen amount with the designed oxygen amount, and comparing the actual carbon monoxide concentration with the target carbon monoxide concentration; According to the comparison result of the operating oxygen amount and the designed oxygen amount, and the comparison result of the actual carbon monoxide concentration and the target carbon monoxide concentration, the overall combustion condition of the boiler is evaluated; The working condition assessment method further includes: Obtaining oxygen concentration detection values ​​and carbon monoxide concentration detection values ​​in the flue gas above each burner in the furnace; Comparing the oxygen concentration detection value with the oxygen concentration warning value, and comparing the carbon monoxide concentration detection value with the carbon monoxide concentration warning value; According to the comparison result of the oxygen concentration detection value and the oxygen concentration warning value, and the comparison result of the carbon monoxide concentration detection value and the carbon monoxide concentration warning value, evaluating the local combustion condition of the boiler; The working condition assessment method further includes: Obtain the temperature detection value of the flue gas at each burner in the furnace; Comparing the temperature detection value with the temperature warning value; According to the comparison result of the temperature detection value and the temperature warning value, the comparison result of the oxygen concentration detection value and the oxygen concentration warning value, and the comparison result of the carbon monoxide concentration detection value and the carbon monoxide concentration warning value, the partial burnout condition of the boiler is evaluated; The working condition assessment method further includes: Obtaining the furnace local negative pressure detection value and flame detection signal at each burner; The combustion conditions of each burner in the furnace are determined based on the comparison of the negative pressure detection value and the warning values ​​respectively corresponding to the flame detection signal.

2. A method for evaluating the multi-element combustion conditions in a counter-firing boiler according to claim 1, characterized in that: Based on the comparison result that the operating oxygen amount is lower than the designed oxygen amount, and the actual carbon monoxide concentration value is higher than the target carbon monoxide concentration value, it is judged that the overall combustion efficiency of the boiler is lower than the expected combustion efficiency.

3. The method for evaluating the multi-element combustion conditions in a counter-firing boiler according to claim 1, characterized in that: Based on the comparison result that the oxygen concentration detection value is lower than the oxygen concentration warning value, and the carbon monoxide concentration detection value is higher than the carbon monoxide concentration warning value, it is judged that the combustion efficiency of the burner is lower than the expected combustion efficiency.

4. The method for evaluating the multi-element combustion conditions in a counter-firing boiler according to claim 1, characterized in that: Based on the comparison results that the temperature detection value is higher than the temperature warning value, the oxygen concentration detection value is lower than the oxygen concentration warning value, and the carbon monoxide concentration detection value is higher than the carbon monoxide concentration warning value, it is judged that the burnout rate of the burner is lower than the expected burnout rate.

5. According to the method for evaluating the multi-element combustion conditions in a counter-firing boiler furnace in claim 1, the combustion conditions of the burner include combustion stability conditions, characterized in that: Obtaining negative pressure detection values ​​at each burner in the furnace; Comparing the negative pressure detection value with the negative pressure warning value; According to the comparison result of the negative pressure detection value and the negative pressure warning value, the combustion stability working condition of each burner is evaluated.

6. A method for evaluating the multi-element combustion conditions in a counter-firing boiler according to claim 5, characterized in that: The step of evaluating the combustion stability working condition of each of the burners according to the comparison result of the negative pressure detection value and the negative pressure warning value comprises: Based on the comparison result that the fluctuation of the negative pressure detection value is greater than the negative pressure warning value, it is determined that the combustion of the burner is unstable and there is a risk of fire extinguishing.

7. According to the method for evaluating the multi-element combustion conditions in a counter-firing boiler furnace in claim 1, the combustion conditions of the burner include combustion stability conditions, characterized in that: Obtaining flame detection signals of the flames of each burner in the furnace; Comparing the flame detection signal with the flame warning value; The combustion stability condition of each of the burners is evaluated based on the comparison result of the flame detection value and the flame warning value.

8. The method for evaluating the multi-element combustion conditions in a counter-firing boiler according to claim 7, characterized in that: The step of evaluating the combustion stability condition of each burner according to the comparison result between the flame detection value and the flame warning value includes: Based on the comparison result that the fluctuation of the flame detection value is greater than the flame warning value, it is determined that the combustion of the burner is unstable and there is a risk of fire extinguishing.

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