A circulating fluidized bed boiler flue gas temperature prediction system and method

Abstract

The application discloses a circulating fluidized bed boiler flue gas temperature prediction system and method, and relates to the technical field of circulating fluidized bed boilers, and comprises the following steps: S1: obtaining flue gas detection temperature of a flue gas temperature sensor, obtaining water temperature in a coal economizer, judging whether the flue gas detection temperature is reasonable through the flue gas detection temperature and the water temperature in the coal economizer, if the judgment result is unreasonable, executing S2, if the judgment result is reasonable, repeatedly executing S1; in the scheme, the historical data of the flue gas temperature and the water temperature in the coal economizer are used to capture detection time, and then the detection time is used to obtain parameters for calculating the surface ash degree value of the flue gas temperature sensor, so that the surface ash historical degree value of the flue gas temperature sensor can be calculated, finally, the surface ash historical degree value of the flue gas temperature sensor is compared with the surface ash degree value of the flue gas temperature sensor to realize cross-validation of the prediction result, so that the prediction result can be ensured to be in a relatively acceptable range.

Description

Technical Field

[0001] This invention relates to the field of circulating fluidized bed boiler technology, specifically to a circulating fluidized bed boiler flue gas temperature prediction system and method. Background Technology

[0002] Circulating fluidized bed boilers are a type of high-efficiency, clean combustion technology boiler widely used in power generation or heating from fuels such as coal, biomass, and waste. Their core feature is the use of "fluidization" technology to achieve efficient fuel combustion and pollutant control.

[0003] Economizers are key heat exchange equipment in the tail flue of circulating fluidized bed boilers. They utilize the waste heat of flue gas to preheat boiler feedwater, thereby reducing the exhaust gas temperature and improving boiler thermal efficiency. Their structure is mostly a serpentine tube bundle, and the material is corrosion-resistant carbon steel or alloy steel.

[0004] Air preheaters are high-efficiency heat exchange devices in the tail flue of circulating fluidized bed boilers. They use the waste heat of flue gas to heat the air required for combustion, which can improve boiler efficiency by 5% to 10%. Through the reverse heat exchange between flue gas and air, they can reduce the flue gas temperature and increase the furnace combustion temperature.

[0005] The flue gas temperature of a circulating fluidized bed boiler should be controlled between 120℃ and 150℃. Excessive temperature will increase the pressure on the economizer and air preheater, and in severe cases, may even damage them. Insufficient temperature will cause low-temperature corrosion damage to the flue and also easily lead to more ash accumulation within the flue. Therefore, the flue gas temperature of a circulating fluidized bed boiler needs continuous monitoring. Temperature sensors are generally used to measure the flue gas temperature. However, in actual use, it has been found that ash inevitably accumulates in the flue of a circulating fluidized bed boiler. This ash accumulation covers and obstructs the temperature sensor, severely affecting its operation. To ensure the accuracy of flue gas temperature acquisition, based on past experience, ash-covered armored thermocouple temperature sensors have an error range of -20℃ to 50℃, while ash-covered resistance temperature sensors have an error range of -10℃ to -30℃. If the flue gas temperature cannot be accurately determined, the circulating fluidized bed boiler must be shut down for maintenance, which not only wastes already burned resources but also reduces work efficiency. To facilitate accurate acquisition of flue gas temperature of circulating fluidized bed boilers even after sensor ash accumulation, we propose a flue gas temperature prediction system and method for circulating fluidized bed boilers. Summary of the Invention

[0006] (a) Technical problems to be solved

[0007] To address the shortcomings of existing technologies, this invention provides a circulating fluidized bed boiler flue gas temperature prediction system and method to solve the aforementioned problems in the prior art.

[0008] (II) Technical Solution

[0009] To achieve the above objectives, the present invention provides the following technical solution: a method for predicting the flue gas temperature of a circulating fluidized bed boiler, comprising the following steps:

[0010] S1: Obtain the flue gas detection temperature from the flue gas temperature sensor, obtain the water temperature inside the economizer, and determine whether the flue gas detection temperature is reasonable by comparing the flue gas detection temperature with the water temperature inside the economizer. If the determination result is unreasonable, execute S2; if the determination result is reasonable, repeat S1.

[0011] S2: Obtain the static pressure inside the air preheater, obtain the air preheater pressure drop value through the static pressure inside the air preheater, obtain the economizer water temperature rise efficiency through the economizer water temperature, obtain the dust accumulation value on the surface of the flue gas temperature sensor through the air preheater pressure drop value and the economizer water temperature rise efficiency, determine whether the flue gas temperature is abnormal due to severe dust accumulation on the surface of the flue gas temperature sensor through the dust accumulation value on the surface of the flue gas temperature sensor, if the determination result is yes, then execute S3, if the determination result is no, then activate the alarm to remind the management personnel to inspect the flue gas temperature sensor circuit;

[0012] S3: Obtain the heat loss temperature from the bed to the furnace outlet, obtain the heat loss temperature from the furnace outlet to the tail heating surface, obtain the bed temperature, and obtain the flue gas prediction temperature through the bed temperature, the heat loss temperature from the bed to the furnace outlet, and the heat loss temperature from the furnace outlet to the tail heating surface.

[0013] S4: Determine whether the prediction result is reasonable by using the flue gas predicted temperature, the water temperature inside the economizer, and the degree of ash accumulation on the surface of the flue gas temperature sensor. If the prediction result is reasonable, define the flue gas predicted temperature as the flue gas temperature. If the prediction result is unreasonable, activate the alarm to remind the management personnel to clean the ash accumulation on the surface of the flue gas temperature sensor.

[0014] Preferably, in S1, the reasonableness of the flue gas detection temperature is determined by comparing the flue gas detection temperature with the water temperature inside the economizer, specifically as follows:

[0015] S101: Set the time interval for flue gas temperature detection, obtain the flue gas temperature according to the time interval, and obtain the flue gas temperature difference by subtracting the current flue gas temperature from the previous flue gas temperature.

[0016] S102: Set the time interval for detecting water temperature inside the economizer, obtain the water temperature inside the economizer according to the time interval, and obtain the water temperature detection difference by subtracting the current water temperature from the previous water temperature.

[0017] S103: Obtain the difference between the flue gas detection temperature and the difference between the water temperature detection temperature within the same time period. Obtain the equilibrium temperature difference by subtracting the difference between the water temperature detection temperature and the flue gas detection temperature. Set a preset threshold for the equilibrium temperature difference range. Determine whether the equilibrium temperature difference is within the preset threshold. If the equilibrium temperature difference is within the preset threshold, the result is that the flue gas detection temperature is reasonable. If the equilibrium temperature difference is not within the preset threshold, determine whether there is a water change. If there is a water change, repeat S101. If there is no water change, the result is that the flue gas detection temperature is unreasonable.

[0018] Preferably, in step S2, the static pressure inside the air preheater is obtained, the air preheater pressure drop is obtained from the static pressure inside the air preheater, the economizer water temperature rise efficiency is obtained from the water temperature inside the economizer, and the dust accumulation level on the surface of the flue gas temperature sensor is obtained from the air preheater pressure drop and the economizer water temperature rise efficiency. Specifically:

[0019] S201: Set the static pressure detection time interval, obtain the static pressure in the air preheater according to the static pressure detection time interval, and obtain the air preheater pressure drop value by subtracting the current static pressure from the previous static pressure.

[0020] S202: Set the heating time interval, obtain the water temperature in the economizer according to the heating time interval, obtain the heating water temperature difference by subtracting the current water temperature from the previous water temperature, and obtain the water temperature heating efficiency by dividing the heating water temperature difference by the heating time interval.

[0021] S203: The air preheater pressure drop and water temperature rise efficiency are converted into dimensionless values ​​in the range of 0 to 1 through normalization processing, and recorded as dimensionless values ​​of air preheater pressure drop and water temperature rise efficiency, respectively. Then, the dimensionless values ​​of air preheater pressure drop and water temperature rise efficiency are weighted and summed to obtain the dust accumulation value on the surface of the flue gas temperature sensor.

[0022] Preferably, in S2, the determination of whether the abnormal smoke temperature is caused by severe dust accumulation on the surface of the smoke temperature sensor is based on the dust accumulation value of the smoke temperature sensor surface. Specifically, this involves: setting a preset threshold for the dust accumulation value of the smoke temperature sensor surface; obtaining the dust accumulation value of the smoke temperature sensor surface; determining whether the dust accumulation value of the smoke temperature sensor surface is less than the preset threshold; if the dust accumulation value of the smoke temperature sensor surface is greater than or equal to the preset threshold, the determination result is yes; if the dust accumulation value of the smoke temperature sensor surface is less than the preset threshold, the determination result is no.

[0023] Preferably, in S3, the heat loss temperature from the bed to the furnace outlet is obtained, specifically as follows:

[0024] S301: Obtain the historical temperature of the bed and the historical temperature of the furnace outlet. Obtain multiple bed-furnace temperature differences by subtracting the historical temperature of the bed from the historical temperature of the furnace outlet within the same time period.

[0025] S302: Arrange the multiple bed furnace temperature differences in order of time from farthest to closest, obtain the 7 bed furnace temperature differences closest to the current time, and sum and average these 7 bed furnace temperature differences to obtain the heat loss temperature from the bed to the furnace outlet.

[0026] Preferably, in S3, the heat loss temperature from the furnace outlet to the tail heating surface is obtained, specifically as follows:

[0027] S303: Obtain the historical temperature of the furnace outlet and the historical temperature of the exhaust gas from the tail heating surface. The temperature difference at the tail of the furnace is obtained by subtracting the historical temperature of the furnace outlet from the historical temperature of the exhaust gas from the tail heating surface within the same time period.

[0028] S304: Arrange multiple furnace tail temperature differences in order of time from farthest to closest, obtain the 7 furnace tail temperature differences closest to the current time, sum and average these 7 furnace tail temperature differences to obtain the heat loss temperature from the furnace outlet to the tail heating surface.

[0029] Preferably, in S3, the predicted flue gas temperature is obtained by the bed temperature, the heat loss temperature from the bed to the furnace outlet, and the heat loss temperature from the furnace outlet to the tail heating surface, specifically as follows:

[0030] S305: Obtain the heat loss temperature from the bed to the furnace outlet, obtain the heat loss temperature from the furnace outlet to the tail heating surface, and obtain the total heat loss temperature by summing the heat loss temperature from the bed to the furnace outlet and the heat loss temperature from the furnace outlet to the tail heating surface.

[0031] S306: Obtain the current bed temperature and calculate the predicted flue gas temperature by subtracting the current bed temperature from the total heat loss temperature.

[0032] Preferably, in S4, the reasonableness of the prediction result is determined by the predicted flue gas temperature, the water temperature inside the economizer, and the degree of ash accumulation on the surface of the flue gas temperature sensor. Specifically:

[0033] S401: Obtain historical flue gas temperature, obtain the water temperature in the economizer at the same time as the historical flue gas temperature and mark it as the historical water temperature in the economizer, obtain the predicted flue gas temperature, obtain the water temperature in the economizer, lock all historical flue gas temperatures that are the same as the predicted flue gas temperature in the historical flue gas temperature and mark them as the first reference data group.

[0034] S402: In the first reference data group, lock all historical water temperatures in economizers that are the same as the water temperature inside the economizer and mark them as the second reference data group.

[0035] S403: Obtain the historical measurement time of the second reference data group respectively, obtain the air preheater pressure drop value at that time through the historical measurement time of the second reference data group and mark it as the historical air preheater pressure drop value, obtain the economizer water temperature rise efficiency at that time through the historical measurement time of the second reference data group and mark it as the historical economizer water temperature rise efficiency, and obtain the historical ash accumulation value on the surface of the flue gas temperature sensor through the historical air preheater pressure drop value and the historical economizer water temperature rise efficiency;

[0036] S404: Arrange all historical dust accumulation values ​​on the surface of all exhaust temperature sensors in ascending order, select the minimum value among all historical dust accumulation values ​​and mark it as the minimum historical dust accumulation value, select the maximum value among all historical dust accumulation values ​​and mark it as the maximum historical dust accumulation value, and obtain the range of historical dust accumulation values ​​through the minimum and maximum historical dust accumulation values;

[0037] S405: Obtain the dust accumulation value on the surface of the smoke exhaust temperature sensor, and determine whether the dust accumulation value is within the range of historical dust accumulation values. If the dust accumulation value is within the range of historical dust accumulation values, the prediction is considered reasonable. If the dust accumulation value is not within the range of historical dust accumulation values, the prediction is considered unreasonable.

[0038] A circulating fluidized bed boiler flue gas temperature prediction system includes the following modules:

[0039] The flue gas temperature anomaly judgment module obtains the flue gas detection temperature from the flue gas temperature sensor and the water temperature inside the economizer. It judges whether the flue gas detection temperature is reasonable by comparing the flue gas detection temperature with the water temperature inside the economizer. If the judgment result is unreasonable, the flue gas temperature sensor ash accumulation anomaly judgment module is executed. If the judgment result is reasonable, the flue gas temperature anomaly judgment module is executed repeatedly.

[0040] The flue gas temperature sensor ash accumulation anomaly judgment module obtains the static pressure inside the air preheater, obtains the air preheater pressure drop value from the static pressure inside the air preheater, obtains the economizer water temperature rise efficiency from the economizer water temperature, and obtains the ash accumulation level value on the surface of the flue gas temperature sensor from the air preheater pressure drop value and the economizer water temperature rise efficiency. It then uses the ash accumulation level value on the surface of the flue gas temperature sensor to determine whether the flue gas temperature is abnormal due to severe ash accumulation on the surface of the flue gas temperature sensor. If the judgment result is yes, the flue gas temperature prediction module is executed; if the judgment result is no, an alarm is activated to remind the management personnel to inspect the flue gas temperature sensor circuit.

[0041] The flue gas temperature prediction module obtains the heat loss temperature from the bed to the furnace outlet, the heat loss temperature from the furnace outlet to the tail heating surface, and the bed temperature. The predicted flue gas temperature is obtained by using the bed temperature, the heat loss temperature from the bed to the furnace outlet, and the heat loss temperature from the furnace outlet to the tail heating surface.

[0042] The prediction result verification module judges whether the prediction result is reasonable by using the predicted flue gas temperature, the water temperature inside the economizer, and the degree of ash accumulation on the surface of the flue gas temperature sensor. If the prediction result is reasonable, the predicted flue gas temperature is defined as the flue gas temperature. If the prediction result is unreasonable, an alarm is triggered to remind the management personnel to clean the ash accumulation on the surface of the flue gas temperature sensor.

[0043] (III) Beneficial Effects

[0044] This invention provides a system and method for predicting flue gas temperature in a circulating fluidized bed boiler, which has the following beneficial effects:

[0045] This solution obtains the degree of ash accumulation on the surface of the flue gas temperature sensor by measuring the air preheater pressure drop and the economizer water temperature rise efficiency. Since the air preheater pressure drop is positively correlated with the degree of ash accumulation in the circulating fluidized bed boiler, and the economizer water temperature rise efficiency is negatively correlated with the degree of ash accumulation in the circulating fluidized bed boiler, the degree of ash accumulation in the circulating fluidized bed boiler can be determined by the air preheater pressure drop and the economizer water temperature rise rate. This facilitates the determination of whether unreasonable temperature is caused by ash accumulation on the sensor surface, and thus facilitates subsequent prediction of flue gas temperature. It also facilitates the determination of the cause of abnormal sensor temperature, and thus helps to remind management personnel whether to clean the sensor surface or repair the sensor circuit, improving the maintenance efficiency of maintenance personnel and indirectly improving work efficiency.

[0046] This solution calculates the heat loss temperature from the furnace outlet to the tail heating surface and the heat loss temperature from the bed to the furnace outlet using historical data. Then, it predicts the flue gas temperature by measuring the current bed temperature. This makes it easier to obtain the current flue gas temperature after the flue gas temperature sensor fails, thus facilitating the control of the flue gas temperature. This helps to avoid unreasonable flue gas temperature affecting the service life of the air preheater and economizer. At the same time, it overcomes the problem that the only option after the flue gas temperature sensor fails is to shut down for maintenance. The corresponding problem can be repaired and maintained after the current combustion is completed.

[0047] In this scheme, historical data of flue gas temperature and economizer water temperature are used to capture the detection time. Then, the parameters for calculating the degree of ash accumulation on the surface of the flue gas temperature sensor are obtained through the detection time. This facilitates the calculation of the historical degree of ash accumulation on the surface of the flue gas temperature sensor. Finally, the historical degree of ash accumulation on the surface of the flue gas temperature sensor is compared with the actual degree of ash accumulation on the surface of the flue gas temperature sensor to achieve cross-validation of the prediction results, thereby ensuring that the prediction results are within a relatively acceptable range. Attached Figure Description

[0048] Figure 1 This is a flowchart of a method for predicting flue gas temperature in a circulating fluidized bed boiler according to the present invention.

[0049] Figure 2 This is a schematic diagram of the structure of a circulating fluidized bed boiler flue gas temperature prediction system according to the present invention. Detailed Implementation

[0050] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0051] Please see Figures 1-2 This invention provides a method for predicting the flue gas temperature of a circulating fluidized bed boiler, comprising the following steps:

[0052] S1: Obtain the flue gas detection temperature from the flue gas temperature sensor, obtain the water temperature inside the economizer, and determine whether the flue gas detection temperature is reasonable by comparing the flue gas detection temperature with the water temperature inside the economizer. If the determination result is unreasonable, execute S2; if the determination result is reasonable, repeat S1.

[0053] S2: Obtain the static pressure inside the air preheater, obtain the air preheater pressure drop value through the static pressure inside the air preheater, obtain the economizer water temperature rise efficiency through the economizer water temperature, obtain the dust accumulation value on the surface of the flue gas temperature sensor through the air preheater pressure drop value and the economizer water temperature rise efficiency, determine whether the flue gas temperature is abnormal due to severe dust accumulation on the surface of the flue gas temperature sensor through the dust accumulation value on the surface of the flue gas temperature sensor, if the determination result is yes, then execute S3, if the determination result is no, then activate the alarm to remind the management personnel to inspect the flue gas temperature sensor circuit;

[0054] S3: Obtain the heat loss temperature from the bed to the furnace outlet, obtain the heat loss temperature from the furnace outlet to the tail heating surface, obtain the bed temperature, and obtain the flue gas prediction temperature through the bed temperature, the heat loss temperature from the bed to the furnace outlet, and the heat loss temperature from the furnace outlet to the tail heating surface.

[0055] S4: Determine whether the prediction result is reasonable by using the flue gas predicted temperature, the water temperature inside the economizer, and the degree of ash accumulation on the surface of the flue gas temperature sensor. If the prediction result is reasonable, define the flue gas predicted temperature as the flue gas temperature. If the prediction result is unreasonable, activate the alarm to remind the management personnel to clean the ash accumulation on the surface of the flue gas temperature sensor.

[0056] In this embodiment, the flue gas temperature is determined to be reasonable by comparing the flue gas temperature with the water temperature inside the economizer. Since the water inside the economizer is heated by the flue gas, the flue gas temperature is positively correlated with the water temperature inside the economizer. Therefore, by comparing the flue gas temperature with the water temperature inside the economizer, it can be determined whether the flue gas temperature detected by the flue gas temperature sensor is within a reasonable range, which facilitates subsequent temperature prediction when the determination result is unreasonable.

[0057] This solution obtains the degree of ash accumulation on the surface of the flue gas temperature sensor by measuring the air preheater pressure drop and the economizer water temperature rise efficiency. Since the air preheater pressure drop is positively correlated with the degree of ash accumulation in the circulating fluidized bed boiler, and the economizer water temperature rise efficiency is negatively correlated with the degree of ash accumulation in the circulating fluidized bed boiler, the degree of ash accumulation in the circulating fluidized bed boiler can be determined by measuring the air preheater pressure drop and the economizer water temperature rise rate. This facilitates the determination of whether unreasonable temperature is caused by ash accumulation on the sensor surface, which in turn facilitates subsequent prediction of flue gas temperature. It also facilitates the determination of the cause of abnormal sensor temperature, which in turn helps to remind management personnel whether to clean the sensor surface or repair the sensor circuit, thus improving the maintenance efficiency of maintenance personnel and indirectly improving work efficiency.

[0058] This solution calculates the heat loss temperature from the furnace outlet to the tail heating surface and the heat loss temperature from the bed to the furnace outlet using historical data. Then, it predicts the flue gas temperature by measuring the current bed temperature. This makes it easier to obtain the current flue gas temperature after the flue gas temperature sensor fails, thus facilitating the control of the flue gas temperature. This helps to avoid unreasonable flue gas temperature affecting the service life of the air preheater and economizer. At the same time, it overcomes the problem that the only option after the flue gas temperature sensor fails is to shut down for maintenance. The corresponding problem can be repaired and maintained after the current combustion is over.

[0059] In this scheme, the historical data of flue gas temperature and economizer water temperature are used to capture the detection time. Then, the parameters for calculating the dust accumulation value on the surface of the flue gas temperature sensor are obtained through the detection time. This facilitates the calculation of the historical dust accumulation value on the surface of the flue gas temperature sensor. Finally, the historical dust accumulation value on the surface of the flue gas temperature sensor is compared with the dust accumulation value on the surface of the flue gas temperature sensor to achieve cross-validation of the prediction results, thereby ensuring that the prediction results are within a relatively acceptable range.

[0060] It is worth mentioning that the weight values ​​in this scheme can be obtained through the analytic hierarchy process (AHP), and the preset threshold values ​​can be obtained through the weight analysis method. These will not be elaborated on further here.

[0061] In S1, the reasonableness of the flue gas detection temperature is determined by comparing it with the water temperature inside the economizer. Specifically:

[0062] S101: Set the time interval for flue gas temperature detection, obtain the flue gas temperature according to the time interval, and obtain the flue gas temperature difference by subtracting the current flue gas temperature from the previous flue gas temperature.

[0063] S102: Set the time interval for detecting water temperature inside the economizer, obtain the water temperature inside the economizer according to the time interval, and obtain the water temperature detection difference by subtracting the current water temperature from the previous water temperature.

[0064] S103: Obtain the difference between the flue gas detection temperature and the difference between the water temperature detection temperature within the same time period. Obtain the equilibrium temperature difference by subtracting the difference between the water temperature detection temperature and the flue gas detection temperature. Set a preset threshold for the equilibrium temperature difference range. Determine whether the equilibrium temperature difference is within the preset threshold. If the equilibrium temperature difference is within the preset threshold, the result is that the flue gas detection temperature is reasonable. If the equilibrium temperature difference is not within the preset threshold, determine whether there is a water change. If there is a water change, repeat S101. If there is no water change, the result is that the flue gas detection temperature is unreasonable.

[0065] In this embodiment, the water inside the economizer is constantly flowing in and out for heating during operation. The water replacement described in this solution refers to the act of completely emptying the water in the economizer and then re-injecting it.

[0066] In S2, the static pressure inside the air preheater is obtained, and the pressure drop value of the air preheater is obtained from the static pressure inside the air preheater. The water temperature rise efficiency of the economizer is obtained from the water temperature inside the economizer. The degree of ash accumulation on the surface of the flue gas temperature sensor is obtained from the air preheater pressure drop value and the economizer water temperature rise efficiency. Specifically:

[0067] S201: Set the static pressure detection time interval, obtain the static pressure in the air preheater according to the static pressure detection time interval, and obtain the air preheater pressure drop value by subtracting the current static pressure from the previous static pressure.

[0068] S202: Set the heating time interval, obtain the water temperature in the economizer according to the heating time interval, obtain the heating water temperature difference by subtracting the current water temperature from the previous water temperature, and obtain the water temperature heating efficiency by dividing the heating water temperature difference by the heating time interval.

[0069] S203: The air preheater pressure drop and water temperature rise efficiency are converted into dimensionless values ​​in the range of 0 to 1 through normalization processing, and recorded as dimensionless values ​​of air preheater pressure drop and water temperature rise efficiency, respectively. Then, the dimensionless values ​​of air preheater pressure drop and water temperature rise efficiency are weighted and summed to obtain the dust accumulation value on the surface of the flue gas temperature sensor.

[0070] In this embodiment, since the air preheater pressure drop is positively correlated with the degree of ash accumulation in the circulating fluidized bed boiler, and the economizer water temperature rise efficiency is negatively correlated with the degree of ash accumulation in the circulating fluidized bed boiler, the degree of ash accumulation in the circulating fluidized bed boiler can be determined by the air preheater pressure drop value and the economizer water temperature rise rate. This makes it easier to determine whether the unreasonable temperature is caused by ash accumulation on the sensor surface, which in turn facilitates the subsequent prediction of flue gas temperature. It also makes it easier to determine the cause of abnormal sensor temperature, which in turn makes it easier to remind management personnel whether to clean the sensor surface or repair the sensor circuit, thus improving the maintenance efficiency of maintenance personnel and indirectly improving work efficiency.

[0071] It is worth mentioning that the parameters of different units are normalized to become dimensionless, which is a publicly available technology. The specific operation steps will not be described in detail here.

[0072] In S2, the degree of dust accumulation on the surface of the exhaust temperature sensor is used to determine whether the abnormal exhaust temperature is caused by severe dust accumulation on the surface of the exhaust temperature sensor. Specifically, a preset threshold for the degree of dust accumulation on the surface of the exhaust temperature sensor is set, the degree of dust accumulation on the surface of the exhaust temperature sensor is obtained, and it is determined whether the degree of dust accumulation on the surface of the exhaust temperature sensor is less than the preset threshold. If the degree of dust accumulation on the surface of the exhaust temperature sensor is greater than or equal to the preset threshold, the determination result is yes; if the degree of dust accumulation on the surface of the exhaust temperature sensor is less than the preset threshold, the determination result is no.

[0073] In S3, the heat loss temperature from the bed to the furnace outlet is obtained, specifically:

[0074] S301: Obtain the historical temperature of the bed and the historical temperature of the furnace outlet. Obtain multiple bed-furnace temperature differences by subtracting the historical temperature of the bed from the historical temperature of the furnace outlet within the same time period.

[0075] S302: Arrange the multiple bed furnace temperature differences in order of time from farthest to closest, obtain the 7 bed furnace temperature differences closest to the current time, and sum and average these 7 bed furnace temperature differences to obtain the heat loss temperature from the bed to the furnace outlet.

[0076] In S3, the heat loss temperature from the furnace outlet to the tail heating surface is obtained, specifically:

[0077] S303: Obtain the historical temperature of the furnace outlet and the historical temperature of the exhaust gas from the tail heating surface. The temperature difference at the tail of the furnace is obtained by subtracting the historical temperature of the furnace outlet from the historical temperature of the exhaust gas from the tail heating surface within the same time period.

[0078] S304: Arrange multiple furnace tail temperature differences in order of time from farthest to closest, obtain the 7 furnace tail temperature differences closest to the current time, sum and average these 7 furnace tail temperature differences to obtain the heat loss temperature from the furnace outlet to the tail heating surface.

[0079] In this embodiment, the historical bed temperature, furnace outlet temperature, and tail heating surface flue gas temperature close to the prediction time are all non-measured abnormal temperatures. By utilizing the historical effective measurement temperatures, it is convenient to accurately predict the subsequent flue gas temperature.

[0080] In S3, the predicted flue gas temperature is obtained through the bed temperature, the heat loss temperature from the bed to the furnace outlet, and the heat loss temperature from the furnace outlet to the tail heating surface. Specifically:

[0081] S305: Obtain the heat loss temperature from the bed to the furnace outlet, obtain the heat loss temperature from the furnace outlet to the tail heating surface, and obtain the total heat loss temperature by summing the heat loss temperature from the bed to the furnace outlet and the heat loss temperature from the furnace outlet to the tail heating surface.

[0082] S306: Obtain the current bed temperature and calculate the predicted flue gas temperature by subtracting the current bed temperature from the total heat loss temperature.

[0083] In this embodiment, the heat loss temperature from the bed to the furnace outlet and the heat loss temperature from the furnace outlet to the tail heating surface in the circulating fluidized bed boiler are the main sources of temperature loss. Therefore, the flue gas temperature can be predicted by the difference between the bed temperature and the total heat loss temperature. In actual work, other sources of temperature loss can be set according to actual parameters such as the sealing status of the circulating fluidized bed boiler. The final temperature in the heat loss can be obtained by summing the temperature in the heat loss with other sources of temperature loss.

[0084] In S4, the reasonableness of the prediction result is determined by the flue gas predicted temperature, the water temperature inside the economizer, and the degree of ash accumulation on the surface of the flue gas temperature sensor. Specifically:

[0085] S401: Obtain historical flue gas temperature, obtain the water temperature in the economizer at the same time as the historical flue gas temperature and mark it as the historical water temperature in the economizer, obtain the predicted flue gas temperature, obtain the water temperature in the economizer, lock all historical flue gas temperatures that are the same as the predicted flue gas temperature in the historical flue gas temperature and mark them as the first reference data group.

[0086] S402: In the first reference data group, lock all historical water temperatures in economizers that are the same as the water temperature inside the economizer and mark them as the second reference data group.

[0087] S403: Obtain the historical measurement time of the second reference data group respectively, obtain the air preheater pressure drop value at that time through the historical measurement time of the second reference data group and mark it as the historical air preheater pressure drop value, obtain the economizer water temperature rise efficiency at that time through the historical measurement time of the second reference data group and mark it as the historical economizer water temperature rise efficiency, and obtain the historical ash accumulation value on the surface of the flue gas temperature sensor through the historical air preheater pressure drop value and the historical economizer water temperature rise efficiency;

[0088] S404: Arrange all historical dust accumulation values ​​on the surface of all exhaust temperature sensors in ascending order, select the minimum value among all historical dust accumulation values ​​and mark it as the minimum historical dust accumulation value, select the maximum value among all historical dust accumulation values ​​and mark it as the maximum historical dust accumulation value, and obtain the range of historical dust accumulation values ​​through the minimum and maximum historical dust accumulation values;

[0089] S405: Obtain the dust accumulation value on the surface of the smoke exhaust temperature sensor, and determine whether the dust accumulation value is within the range of historical dust accumulation values. If the dust accumulation value is within the range of historical dust accumulation values, the prediction is considered reasonable. If the dust accumulation value is not within the range of historical dust accumulation values, the prediction is considered unreasonable.

[0090] In this embodiment, the scheme finds the detection time that matches the current flue gas predicted temperature and economizer water temperature in historical data. Based on the captured detection time, it obtains the corresponding economizer water temperature rise efficiency and air preheater pressure drop value within that time, thereby calculating the dust accumulation level on the surface of the flue gas temperature sensor at that time, thus obtaining the historical dust accumulation level range. Finally, it compares the current dust accumulation level on the surface of the flue gas temperature sensor with the historical dust accumulation level range to cross-validate the accuracy of the prediction results.

[0091] Please see Figures 1-2 This invention provides a circulating fluidized bed boiler flue gas temperature prediction system, comprising the following modules:

[0092] The flue gas temperature anomaly judgment module obtains the flue gas detection temperature from the flue gas temperature sensor and the water temperature inside the economizer. It judges whether the flue gas detection temperature is reasonable by comparing the flue gas detection temperature with the water temperature inside the economizer. If the judgment result is unreasonable, the flue gas temperature sensor ash accumulation anomaly judgment module is executed. If the judgment result is reasonable, the flue gas temperature anomaly judgment module is executed repeatedly.

[0093] The flue gas temperature sensor ash accumulation anomaly judgment module obtains the static pressure inside the air preheater, obtains the air preheater pressure drop value from the static pressure inside the air preheater, obtains the economizer water temperature rise efficiency from the economizer water temperature, and obtains the ash accumulation level value on the surface of the flue gas temperature sensor from the air preheater pressure drop value and the economizer water temperature rise efficiency. It then uses the ash accumulation level value on the surface of the flue gas temperature sensor to determine whether the flue gas temperature is abnormal due to severe ash accumulation on the surface of the flue gas temperature sensor. If the judgment result is yes, the flue gas temperature prediction module is executed; if the judgment result is no, an alarm is activated to remind the management personnel to inspect the flue gas temperature sensor circuit.

[0094] The flue gas temperature prediction module obtains the heat loss temperature from the bed to the furnace outlet, the heat loss temperature from the furnace outlet to the tail heating surface, and the bed temperature. The predicted flue gas temperature is obtained by using the bed temperature, the heat loss temperature from the bed to the furnace outlet, and the heat loss temperature from the furnace outlet to the tail heating surface.

[0095] The prediction result verification module judges whether the prediction result is reasonable by using the predicted flue gas temperature, the water temperature inside the economizer, and the degree of ash accumulation on the surface of the flue gas temperature sensor. If the prediction result is reasonable, the predicted flue gas temperature is defined as the flue gas temperature. If the prediction result is unreasonable, an alarm is triggered to remind the management personnel to clean the ash accumulation on the surface of the flue gas temperature sensor.

[0096] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented in software, the above embodiments can be implemented, in whole or in part, as a computer program product. Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution.

[0097] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0098] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A method for predicting flue gas temperature in a circulating fluidized bed boiler, characterized in that, Includes the following steps: S1: Obtain the flue gas detection temperature from the flue gas temperature sensor, obtain the water temperature inside the economizer, and determine whether the flue gas detection temperature is reasonable by comparing the flue gas detection temperature with the water temperature inside the economizer. If the determination result is unreasonable, execute S2; if the determination result is reasonable, repeat S1. S2: Obtain the static pressure inside the air preheater, obtain the air preheater pressure drop value through the static pressure inside the air preheater, obtain the economizer water temperature rise efficiency through the economizer water temperature, obtain the dust accumulation value on the surface of the flue gas temperature sensor through the air preheater pressure drop value and the economizer water temperature rise efficiency, determine whether the flue gas temperature is abnormal due to severe dust accumulation on the surface of the flue gas temperature sensor through the dust accumulation value on the surface of the flue gas temperature sensor, if the determination result is yes, then execute S3, if the determination result is no, then activate the alarm to remind the management personnel to inspect the flue gas temperature sensor circuit; In S2, the static pressure inside the air preheater is obtained, and the pressure drop value of the air preheater is obtained from the static pressure inside the air preheater. The water temperature rise efficiency of the economizer is obtained from the water temperature inside the economizer. The degree of ash accumulation on the surface of the flue gas temperature sensor is obtained from the air preheater pressure drop value and the economizer water temperature rise efficiency. Specifically: S201: Set the static pressure detection time interval, obtain the static pressure in the air preheater according to the static pressure detection time interval, and obtain the air preheater pressure drop value by subtracting the current static pressure from the previous static pressure. S202: Set the heating time interval, obtain the water temperature in the economizer according to the heating time interval, obtain the heating water temperature difference by subtracting the current water temperature from the previous water temperature, and obtain the water temperature heating efficiency by dividing the heating water temperature difference by the heating time interval. S203: The air preheater pressure drop and water temperature rise efficiency are converted into dimensionless values ​​in the range of 0 to 1 by normalization, and recorded as dimensionless values ​​of air preheater pressure drop and water temperature rise efficiency, respectively. Then, the dimensionless values ​​of air preheater pressure drop and water temperature rise efficiency are weighted and summed to obtain the dust accumulation value on the surface of the flue gas temperature sensor. S3: Obtain the heat loss temperature from the bed to the furnace outlet, obtain the heat loss temperature from the furnace outlet to the tail heating surface, obtain the bed temperature, and obtain the flue gas prediction temperature through the bed temperature, the heat loss temperature from the bed to the furnace outlet, and the heat loss temperature from the furnace outlet to the tail heating surface. S4: Determine whether the prediction result is reasonable by using the flue gas predicted temperature, the water temperature inside the economizer, and the degree of ash accumulation on the surface of the flue gas temperature sensor. If the prediction result is reasonable, define the flue gas predicted temperature as the flue gas temperature. If the prediction result is unreasonable, activate the alarm to remind the management personnel to clean the ash accumulation on the surface of the flue gas temperature sensor. In S4, the reasonableness of the prediction result is determined by the flue gas predicted temperature, the water temperature inside the economizer, and the degree of ash accumulation on the surface of the flue gas temperature sensor. Specifically: S401: Obtain historical flue gas temperature, obtain the water temperature in the economizer at the same time as the historical flue gas temperature and mark it as the historical water temperature in the economizer, obtain the predicted flue gas temperature, obtain the water temperature in the economizer, lock all historical flue gas temperatures that are the same as the predicted flue gas temperature in the historical flue gas temperature and mark them as the first reference data group. S402: In the first reference data group, lock all historical water temperatures in economizers that are the same as the water temperature inside the economizer and mark them as the second reference data group. S403: Obtain the historical measurement time of the second reference data group respectively, obtain the air preheater pressure drop value at that time through the historical measurement time of the second reference data group and mark it as the historical air preheater pressure drop value, obtain the economizer water temperature rise efficiency at that time through the historical measurement time of the second reference data group and mark it as the historical economizer water temperature rise efficiency, and obtain the historical ash accumulation value on the surface of the flue gas temperature sensor through the historical air preheater pressure drop value and the historical economizer water temperature rise efficiency; S404: Arrange all historical dust accumulation values ​​on the surface of all exhaust temperature sensors in ascending order, select the minimum value among all historical dust accumulation values ​​and mark it as the minimum historical dust accumulation value, select the maximum value among all historical dust accumulation values ​​and mark it as the maximum historical dust accumulation value, and obtain the range of historical dust accumulation values ​​through the minimum and maximum historical dust accumulation values; S405: Obtain the dust accumulation value on the surface of the smoke exhaust temperature sensor, and determine whether the dust accumulation value is within the range of historical dust accumulation values. If the dust accumulation value is within the range of historical dust accumulation values, the prediction is considered reasonable. If the dust accumulation value is not within the range of historical dust accumulation values, the prediction is considered unreasonable.

2. The method for predicting flue gas temperature of a circulating fluidized bed boiler according to claim 1, characterized in that: In S1, the reasonableness of the flue gas detection temperature is determined by comparing it with the water temperature inside the economizer. Specifically: S101: Set the time interval for flue gas temperature detection, obtain the flue gas temperature according to the time interval, and obtain the flue gas temperature difference by subtracting the current flue gas temperature from the previous flue gas temperature. S102: Set the time interval for detecting water temperature inside the economizer, obtain the water temperature inside the economizer according to the time interval, and obtain the water temperature detection difference by subtracting the current water temperature from the previous water temperature. S103: Obtain the difference between the flue gas detection temperature and the difference between the water temperature detection temperature within the same time period. Obtain the equilibrium temperature difference by subtracting the difference between the water temperature detection temperature and the flue gas detection temperature. Set a preset threshold for the equilibrium temperature difference range. Determine whether the equilibrium temperature difference is within the preset threshold. If the equilibrium temperature difference is within the preset threshold, the result is that the flue gas detection temperature is reasonable. If the equilibrium temperature difference is not within the preset threshold, determine whether there is a water change. If there is a water change, repeat S101. If there is no water change, the result is that the flue gas detection temperature is unreasonable.

3. The method for predicting flue gas temperature of a circulating fluidized bed boiler according to claim 1, characterized in that: In S2, the degree of dust accumulation on the surface of the exhaust temperature sensor is used to determine whether the abnormal exhaust temperature is caused by severe dust accumulation on the surface of the exhaust temperature sensor. Specifically, a preset threshold for the degree of dust accumulation on the surface of the exhaust temperature sensor is set, the degree of dust accumulation on the surface of the exhaust temperature sensor is obtained, and it is determined whether the degree of dust accumulation on the surface of the exhaust temperature sensor is less than the preset threshold. If the degree of dust accumulation on the surface of the exhaust temperature sensor is greater than or equal to the preset threshold, the determination result is yes; if the degree of dust accumulation on the surface of the exhaust temperature sensor is less than the preset threshold, the determination result is no.

4. The method for predicting flue gas temperature of a circulating fluidized bed boiler according to claim 1, characterized in that: In S3, the heat loss temperature from the bed to the furnace outlet is obtained, specifically: S301: Obtain the historical temperature of the bed and the historical temperature of the furnace outlet. Obtain multiple bed-furnace temperature differences by subtracting the historical temperature of the bed from the historical temperature of the furnace outlet within the same time period. S302: Arrange the multiple bed furnace temperature differences in order of time from farthest to closest, obtain the 7 bed furnace temperature differences closest to the current time, and sum and average these 7 bed furnace temperature differences to obtain the heat loss temperature from the bed to the furnace outlet.

5. The method for predicting flue gas temperature of a circulating fluidized bed boiler according to claim 1, characterized in that: In S3, the heat loss temperature from the furnace outlet to the tail heating surface is obtained, specifically: S303: Obtain the historical temperature of the furnace outlet and the historical temperature of the exhaust gas from the tail heating surface. The temperature difference at the tail of the furnace is obtained by subtracting the historical temperature of the furnace outlet from the historical temperature of the exhaust gas from the tail heating surface within the same time period. S304: Arrange multiple furnace tail temperature differences in order of time from farthest to closest, obtain the 7 furnace tail temperature differences closest to the current time, sum and average these 7 furnace tail temperature differences to obtain the heat loss temperature from the furnace outlet to the tail heating surface.

6. The method for predicting flue gas temperature of a circulating fluidized bed boiler according to claim 1, characterized in that: In S3, the predicted flue gas temperature is obtained through the bed temperature, the heat loss temperature from the bed to the furnace outlet, and the heat loss temperature from the furnace outlet to the tail heating surface. Specifically: S305: Obtain the heat loss temperature from the bed to the furnace outlet, obtain the heat loss temperature from the furnace outlet to the tail heating surface, and obtain the total heat loss temperature by summing the heat loss temperature from the bed to the furnace outlet and the heat loss temperature from the furnace outlet to the tail heating surface. S306: Obtain the current bed temperature and calculate the predicted flue gas temperature by subtracting the current bed temperature from the total heat loss temperature.

7. A circulating fluidized bed boiler flue gas temperature prediction system, applied to the circulating fluidized bed boiler flue gas temperature prediction method according to any one of claims 1-6, characterized in that, Includes the following modules: The flue gas temperature anomaly judgment module obtains the flue gas detection temperature from the flue gas temperature sensor and the water temperature inside the economizer. It judges whether the flue gas detection temperature is reasonable by comparing the flue gas detection temperature with the water temperature inside the economizer. If the judgment result is unreasonable, the flue gas temperature sensor ash accumulation anomaly judgment module is executed. If the judgment result is reasonable, the flue gas temperature anomaly judgment module is executed repeatedly. The flue gas temperature sensor ash accumulation anomaly judgment module obtains the static pressure inside the air preheater, obtains the air preheater pressure drop value from the static pressure inside the air preheater, obtains the economizer water temperature rise efficiency from the economizer water temperature, and obtains the ash accumulation level value on the surface of the flue gas temperature sensor from the air preheater pressure drop value and the economizer water temperature rise efficiency. It then uses the ash accumulation level value on the surface of the flue gas temperature sensor to determine whether the flue gas temperature is abnormal due to severe ash accumulation on the surface of the flue gas temperature sensor. If the judgment result is yes, the flue gas temperature prediction module is executed; if the judgment result is no, an alarm is activated to remind the management personnel to inspect the flue gas temperature sensor circuit. The flue gas temperature prediction module obtains the heat loss temperature from the bed to the furnace outlet, the heat loss temperature from the furnace outlet to the tail heating surface, and the bed temperature. The predicted flue gas temperature is obtained by using the bed temperature, the heat loss temperature from the bed to the furnace outlet, and the heat loss temperature from the furnace outlet to the tail heating surface. The prediction result verification module judges whether the prediction result is reasonable by using the predicted flue gas temperature, the water temperature inside the economizer, and the degree of ash accumulation on the surface of the flue gas temperature sensor. If the prediction result is reasonable, the predicted flue gas temperature is defined as the flue gas temperature. If the prediction result is unreasonable, an alarm is triggered to remind the management personnel to clean the ash accumulation on the surface of the flue gas temperature sensor.

Images