Real-time control method and system applied to combustion of circulating fluidized bed boiler

Abstract

The invention discloses a real-time control method and system applied to combustion of a circulating fluidized bed boiler, and relates to the technical field of circulating fluidized beds, and the real-time control method comprises the following steps: arranging a plurality of temperature monitoring points in a bed layer and installing a thermocouple device to realize real-time monitoring and recording of the bed temperature; identifying and analyzing a plurality of indexes influencing the bed temperature, and respectively fitting influence functions on the bed temperature and the stabilization time when each index is increased or decreased by utilizing a control variable method and a least square method; the system monitors the temperature change of each point in real time, compares the temperature change with a preset normal temperature range, and flexibly adopts a single-monitoring-point or multi-monitoring-point adjustment strategy for abnormal monitoring points; the single monitoring point strategy determines an optimal adjustment scheme by screening an influence function; the multi-monitoring-point strategy focuses on searching public indexes and adjusting modes, and comprehensive optimization is achieved in combination with a single-point strategy; through intelligent decision making of the temperature adjusting process of the circulating fluidized bed, accurate and real-time control over combustion of the circulating fluidized bed boiler is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of circulating fluidized bed technology, and particularly to a real-time control method and system applied to the combustion of a circulating fluidized bed boiler. Background Art

[0002] As an efficient and clean combustion technology, the circulating fluidized bed boiler has been widely used in the fields of industrial production and energy utilization. Its unique combustion mode, that is, the flow region formed by solid particles and fluid (usually gas), enables the fuel to burn more fully, improving the combustion efficiency and heat utilization rate; however, the combustion process of the circulating fluidized bed boiler is complex and changeable, affected by various factors, and among them, the control of the bed temperature is the key to ensuring the safe and stable operation of the boiler;

[0003] The bed temperature is an important parameter in the combustion process of the circulating fluidized bed boiler, which directly affects the combustion efficiency of the fuel, the thermal efficiency of the boiler, and the emission of pollutants; too high or too low bed temperature will lead to problems such as unstable combustion, decreased thermal efficiency, and equipment damage; therefore, real-time monitoring and effective control of the bed temperature are important means to ensure the normal operation of the circulating fluidized bed boiler;

[0004] There are various ways to adjust the bed temperature. Most traditional bed temperature control methods only adjust the bed temperature by adjusting the coal feeding amount, primary air volume, and secondary air volume, while ignoring other ways to adjust the bed temperature; in addition, when the traditional bed temperature control method monitors abnormal bed temperature, it mostly relies on manual experience and simple control logic to select the bed temperature adjustment method, which is difficult to adapt to various changes in the boiler combustion process and is difficult to accurately and quickly select the bed temperature adjustment method with the least impact on the combustion state at other positions from multiple bed temperature adjustment methods, resulting in low control accuracy of the circulating fluidized bed. Summary of the Invention

[0005] (1) Technical Problems to be Solved

[0006] Aiming at the technical problems in the background art, the present invention proposes a real-time control method and system applied to the combustion of a circulating fluidized bed boiler. By comprehensively considering the influence of multiple indicators such as coal feeding amount, primary air volume, secondary air volume, fuel particle size, return material amount, and slag discharge amount on the bed temperature, and when the bed temperature is monitored to be abnormal, according to the number of abnormal monitoring points and the temperature deviation, through the calculation of the priority determination strategy, comprehensive temperature influence index, and comprehensive time influence index, quickly and accurately select the bed temperature adjustment method with the least impact on the combustion state at other positions from multiple adjustment methods; thus solving the technical problems recorded in the background art.

[0007] (2) Technical Solutions

[0008] To achieve the above object, the present invention is realized through the following technical solutions:

[0009] A real-time control method applied to the combustion of a circulating fluidized bed boiler, comprising:

[0010] Placing thermocouple devices at several temperature monitoring points in the circulating fluidized bed layer to real-time monitor the bed temperature at each temperature monitoring point during the operation of the circulating fluidized bed, and recording the obtained bed temperature data in a temperature broken line graph after preprocessing;

[0011] Obtaining several indexes affecting the bed temperature; respectively fitting the influence functions of each index on the bed temperature at different temperature monitoring points when increasing and decreasing based on the control variable method and the least square method; recording and accumulating the stable time after each adjustment, and using the least square method to fit the stable time functions of each index on the bed temperature at different temperature monitoring points when increasing and decreasing;

[0012] Real-time monitoring the temperature changes of each temperature monitoring point of the circulating fluidized bed and comparing with the set normal temperature range; when an abnormal monitoring point is found, execute a single monitoring point or multi-monitoring point adjustment strategy according to the number of abnormal monitoring points;

[0013] The single monitoring point adjustment strategy determines the adjustment method and value by screening the bed temperature influence function, calculates the comprehensive temperature influence index and the comprehensive time influence index through the priority determination strategy, and comprehensively selects the best adjustment method;

[0014] The multi-monitoring point adjustment strategy determines whether all abnormal points can be adjusted to the normal temperature range under the maximum adjustment value in the common adjustment method by screening the common indexes and adjustment methods, and combines with the single monitoring point adjustment strategy to comprehensively select the best adjustment method.

[0015] Specifically, obtaining the height h of the dense phase region in the circulating fluidized bed layer, and taking the dense phase region as well as the h height as the alternative layers for temperature monitoring points; at any four target points are randomly selected on the alternative layer at the height as the temperature monitoring points of this alternative layer, and it is required that there is the following relationship between any one temperature monitoring point and the other three temperature monitoring points: among the other three temperature monitoring points,

[0016] (1) There are two temperature monitoring points with the same distance from the selected temperature monitoring point;

[0017] (2) The connection line between the temperature monitoring point other than the two temperature monitoring points in (1) and the selected temperature monitoring point passes through the center of the corresponding alternative layer;

[0018] Taking the temperature monitoring points selected on the alternative layer at height and translating them upward by height and Height, respectively obtaining Temperature monitoring points selected on the alternative layers at the height of and at the height of h.

[0019] Specifically, the several indexes affecting the bed temperature include 6 indexes: coal feeding amount, primary air volume, secondary air volume, fuel particle size, return material amount, and slag discharge amount, and are sequentially denoted as E 1 to E 6 ;

[0020] Operating the circulating fluidized bed according to the standard values of the 6 indexes; when the combustion in the bed layer of the circulating fluidized bed is stable, selecting one index E from the 6 indexes for fitting the bed temperature influence function and the stable time function i , and keeping the values of the remaining 5 indexes unchanged; within the allowable range, gradually increasing or decreasing the value of the selected index E i , and when the combustion in the bed layer of the circulating fluidized bed is stable again, recording the bed layer temperature at each temperature monitoring point, and the time from adjusting the index to the combustion in the bed layer being stable again; among them, the allowable range is the reasonable interval of the value of this index on the premise of not affecting the safe and stable operation of the boiler, and is determined based on historical operation experience.

[0021] Furthermore, based on independently increasing or decreasing the value of the selected index E i for multiple times, and the corresponding bed layer temperature value T at each temperature monitoring point after each adjustment, using the least squares method to fit the bed temperature influence function, obtaining and respectively represent the bed temperature influence functions at each temperature monitoring point when the value e i of the selected index E i increases and decreases, where P represents the temperature monitoring point, and u and d respectively represent the increase and decrease of the value e i of the selected index E i . respectively represent the slopes of the temperature influence functions at the temperature monitoring point P when the selected index E i increases and decreases, respectively represent the intercepts of the temperature influence functions at the temperature monitoring point P when the selected index E i increases and decreases.

[0022] Specifically, based on independently increasing or decreasing the value of the selected index E i for multiple times, recording the time required for the combustion in the bed layer to be stable again after each adjustment; accumulating these stable times after single adjustments to obtain the total stable time t after multiple adjustments;

[0023] Using the least squares method to fit the stable time function, obtaining and respectively represent the selected index E i the value e i of the bed temperature influence function at each temperature monitoring point when increasing and decreasing, where respectively represent the selected index E i the slope of the stable time function at the temperature monitoring point P when increasing and decreasing, respectively represent the selected index E i the intercept of the stable time function at the temperature monitoring point P when increasing and decreasing.

[0024] Specifically, during the operation of the circulating fluidized bed, the temperature changes at each temperature monitoring point in the line graph are monitored in real time; the temperatures at each temperature monitoring point monitored in real time are compared with the corresponding normal temperature ranges T 1 、T 2 、T 3 in real time, where T 1 、T 2 、T 3 represent the normal temperature ranges in the dense phase region and at the height of h;

[0025] If the temperature at any temperature monitoring point other than the abnormal monitoring point is detected to exceed the corresponding normal temperature range, mark this temperature monitoring point as an abnormal monitoring point and execute the judgment strategy;

[0026] The judgment strategy is used to judge the number n of abnormal monitoring points at this time. If n = 1, execute the single monitoring point adjustment strategy; otherwise, execute the multi-monitoring point adjustment strategy.

[0027] Specifically, the single monitoring point adjustment strategy is specifically as follows:

[0028] Further judge the size relationship between the temperature at this abnormal monitoring point and the corresponding normal temperature range. If the temperature at this abnormal monitoring point exceeds the upper limit of the corresponding normal temperature range, it means that the temperature at this abnormal monitoring point is higher than the normal range; screen out all slopes or less than 0 of the bed temperature influence function corresponding to the index E i ; if the temperature at this abnormal monitoring point is lower than the lower limit of the corresponding normal temperature range, it means that the temperature at this abnormal monitoring point is lower than the normal range; screen out all slopes or greater than 0 of the bed temperature influence function corresponding to the index E i ; determine the priority strategy for the screened indicators.

[0029] Specifically, the priority determination strategy is used to screen out the best adjustment method, including:

[0030] Determine the adjustment method and adjustment value for the selected indicators in sequence; after determining the adjustment method and adjustment value, calculate the temperature change at all other temperature monitoring points after adjustment according to the adjustment method and adjustment value; and determine whether the adjusted temperature at all other temperature monitoring points exceeds the corresponding normal temperature range. If the adjusted temperature at any temperature monitoring point exceeds the corresponding normal temperature range, delete the adjustment method; otherwise, record the adjustment method in the set of candidate adjustment methods.

[0031] Furthermore, the priority determination strategy further includes:

[0032] Based on the relationship between the adjusted temperature at each of the remaining temperature monitoring points and the median of the corresponding normal temperature range, calculate the comprehensive temperature influence index for each adjustment method in the set of candidate adjustment methods; based on the magnitude relationship between the stabilization time after adjustment at each of the remaining temperature monitoring points and the stabilization time after adjustment at the abnormal monitoring points, calculate the comprehensive time influence index for each adjustment method in the set of candidate adjustment methods;

[0033] Add the comprehensive temperature influence index and the comprehensive time influence index for each adjustment method in the set of candidate adjustment methods, and sort all adjustment methods in descending order according to the sum, and select the adjustment method ranked first for adjusting the bed temperature.

[0034] Specifically, the multi-monitoring point adjustment strategy is specifically as follows:

[0035] Based on the single-monitoring point adjustment strategy, according to the magnitude relationship between the temperature at each abnormal monitoring point and the corresponding normal temperature range, respectively screen out the indicators for adjusting the bed temperature at each abnormal monitoring point, and determine the adjustment method and adjustment value for the selected indicators;

[0036] Screen out the common indicators and adjustment methods for multiple abnormal monitoring points, and calculate the adjustment value for each abnormal monitoring point under this adjustment method. Determine whether the temperature at all abnormal monitoring points can be adjusted to the corresponding normal temperature range when adjusting according to the maximum adjustment value; if so, continue to determine whether the adjusted temperature at all other temperature monitoring points exceeds the corresponding normal temperature range under this adjustment method and adjustment value. If the adjusted temperature at all other temperature monitoring points does not exceed the corresponding normal temperature range, adjust the bed temperature at each abnormal monitoring point according to this adjustment method and adjustment value; if the adjusted temperature at any temperature monitoring point exceeds the corresponding normal temperature range, perform the single-monitoring point adjustment strategy in sequence according to the magnitude of the value by which the abnormal monitoring point exceeds the corresponding normal temperature range to select the best adjustment method.

[0037] A real-time control system applied to the combustion of a circulating fluidized bed boiler, including:

[0038] The data acquisition module places thermocouple devices at several temperature monitoring points in the circulating fluidized bed bed layer, and monitors the bed temperature at each temperature monitoring point in real time during the operation of the circulating fluidized bed. After preprocessing the obtained bed temperature data, it is recorded in the temperature line graph;

[0039] The index determination module obtains several indexes for adjusting the bed temperature based on theoretical knowledge, specifically including 6 indexes: coal feeding amount, primary air volume, secondary air volume, fuel particle size, return material amount, and slag discharge amount;

[0040] The function fitting module includes a bed temperature influence function fitting unit and a stable time function fitting unit; the bed temperature influence function fitting unit respectively fits the bed temperature influence functions of each index when increasing and decreasing for different temperature monitoring points based on the control variable method and the least square method; the stable time function fitting unit records and accumulates the stable time after each adjustment, and uses the least square method to fit the stable time functions of each index when increasing and decreasing for different temperature monitoring points;

[0041] The adjustment method determination module includes a single monitoring point adjustment unit and a multi-monitoring point adjustment unit; the single monitoring point adjustment unit is used to execute the single monitoring point adjustment strategy when it is judged that the number of abnormal monitoring points is single. By screening the bed temperature influence function, the adjustment method and value are determined, and the comprehensive temperature influence index and comprehensive time influence index are calculated through the priority determination strategy, and the best adjustment method is comprehensively selected; the multi-monitoring point adjustment unit is used to screen the common indexes and adjustment methods when it is judged that the number of abnormal monitoring points is multiple, judge whether all abnormal points can be adjusted to the normal temperature range under the maximum adjustment value in the common adjustment method, and combine the single monitoring point adjustment strategy to comprehensively select the best adjustment method.

[0042] (III) Beneficial effects

[0043] The present invention provides a real-time control method and system applied to the combustion of a circulating fluidized bed boiler, and has the following beneficial effects:

[0044] 1. By scientifically selecting temperature monitoring points, accurately placing thermocouple devices, strictly preprocessing bed temperature data, and real-time drawing temperature line graphs, the comprehensive and accurate monitoring of the temperature in the dense phase area of the circulating fluidized bed is realized, providing strong data support for timely detecting combustion abnormalities, optimizing the combustion process, and improving the boiler operation efficiency;

[0045] 2. By systematically identifying multiple key indicators affecting the bed temperature and applying the control variable method and the least squares method, the influence functions of these indicators on the bed temperature at different temperature monitoring points when increasing and decreasing, as well as the corresponding stable time functions, were respectively fitted. This provides precise mathematical model support for real-time adjustment of combustion parameters and optimization of the combustion process, helps achieve rapid and stable control of the bed temperature, and further improves the combustion efficiency and operation stability of the circulating fluidized bed boiler.

[0046] 3. By real-time monitoring the temperature changes at each temperature monitoring point of the circulating fluidized bed and comparing with the set normal temperature range, this design can promptly detect and handle abnormal bed temperatures, effectively avoiding boiler operation problems caused by excessively high or low bed temperatures. For abnormal monitoring points, the design proposes a single monitoring point adjustment strategy and a multi-monitoring point adjustment strategy. These two strategies can flexibly select adjustment methods and values according to different abnormal situations to ensure that the bed temperature quickly and accurately returns to the normal range, thereby improving the combustion efficiency of the boiler.

[0047] 4. When formulating the adjustment strategy, factors such as the bed temperature influence function, the priority determination strategy, and the comprehensive temperature influence index and comprehensive time influence index are fully considered. By screening the indicators corresponding to the bed temperature influence function and determining their adjustment methods and values, the design can accurately find the factors with the greatest influence on the bed temperature and make targeted adjustments. By calculating the comprehensive temperature influence index and comprehensive time influence index, the design can comprehensively evaluate the overall influence of different adjustment methods on the bed temperature, thereby selecting the best adjustment method. This refined adjustment strategy not only improves the control accuracy of the boiler but also enhances the adaptability of the boiler to different working conditions, ensuring the stable operation of the boiler. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a step flow chart of a real-time control method for the combustion of a circulating fluidized bed boiler provided by the present invention.

[0049] Figure 2 It is an implementation flow chart of a real-time control system for the combustion of a circulating fluidized bed boiler provided by the present invention.

[0050] Figure 3 It is a structural schematic diagram of a real-time control system for the combustion of a circulating fluidized bed boiler provided by the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0051] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0052] Referring to Figure 1 and Figure 2 , the present invention provides a real-time control method applied to the combustion of a circulating fluidized bed boiler, including:

[0053] Step 1: Place thermocouple devices at several temperature monitoring points in the circulating fluidized bed layer to monitor the bed temperature at each temperature monitoring point in real time during the operation of the circulating fluidized bed. After preprocessing the obtained bed temperature data, record it in a temperature line graph;

[0054] The following steps are included in Step 1:

[0055] Step 101: Select 12 temperature monitoring points in the bed layer of the circulating fluidized bed. The specific selection method is as follows: Obtain the height h of the dense phase region in the bed layer of the circulating fluidized bed, and use the dense phase region and the h height as the alternative layers for temperature monitoring points; Since the shape of the dense phase region in the circulating fluidized bed layer is a cylinder, the graph of each alternative layer is a circle; At height, arbitrarily select four target points on the alternative layer as the temperature monitoring points of this alternative layer. It is required that there is the following relationship between any one temperature monitoring point and the other three temperature monitoring points: Among the other three temperature monitoring points, (1) there are two temperature monitoring points with the same distance from the selected temperature monitoring point; (2) the connection line between the temperature monitoring point other than the two temperature monitoring points in (1) and the selected temperature monitoring point passes through the center of the corresponding alternative layer; Denote the four selected temperature monitoring points as A 1 、B 1 、C 1 and D 1 ;

[0056] The temperature monitoring points selected on the alternative layer at height are respectively translated upward by height and height to respectively obtain the temperature monitoring points selected on the alternative layer at height and the alternative layer at h height. Denote the selected temperature monitoring points as A 2 、B 2 、C 2 and D 2 as well as A 3 、B 3 、C 3and D 3 ; The temperature monitoring points with the same letter mark are in an upward and downward translation relationship, and the subscripts 1, 2, and 3 correspond to the temperature monitoring points in the dense phase region, respectively. Temperature monitoring point at height h;

[0057] According to the above method, a total of 12 temperature monitoring points were selected;

[0058] The bed layer in the circulating fluidized bed refers to the flow area formed by solid particles and fluid (usually gas), in which the solid particles are in a fluidized state under the action of gas, mainly including two areas: dense phase area and dilute phase area. The dense phase area is located at the lower part of the bed layer, with a higher concentration of solid particles. It is the main place for combustion and chemical reactions and also the area where heat release is more concentrated. By monitoring the temperature in this area, abnormal conditions in the combustion process can be discovered and adjusted in time.

[0059] Step 102: placing a thermocouple device at each selected temperature monitoring point to monitor the temperature change at the corresponding position of the dense phase region when the circulating fluidized bed is running;

[0060] The basic principle of the thermocouple device is the thermoelectric effect, that is, when the temperature changes, the free electrons in the conductor or semiconductor will be affected by the thermal energy, thereby generating an electric potential difference; the thermocouple is composed of two wires of different materials, one end of which is connected together to form the measuring end, and the other end is connected to the measuring instrument to form the reference end; when the temperature of the measuring end changes, due to the different thermoelectric properties of the two materials, a potential difference will be generated. There is a certain functional relationship between this potential difference and the temperature. By measuring this potential difference, the temperature value of the measuring end can be determined;

[0061] Step 103, preprocessing the bed temperature data acquired in real time, including data cleaning, data calibration and data normalization; first, data cleaning is performed to remove abnormal values ​​or missing values ​​caused by thermocouple device failure, data transmission error or external interference to ensure the accuracy and completeness of the data; second, data calibration is performed to correct the measured value according to the calibration certificate of the thermocouple device to eliminate system errors and improve the accuracy of the data; finally, data normalization is performed to convert the bed temperature data of each temperature monitoring point into a unified dimension range to facilitate subsequent data analysis and comparison;

[0062] Step 104, setting a temperature line graph, each temperature monitoring point corresponds to a line, the horizontal axis of the line represents time, the vertical axis represents temperature, and each line is associated with the corresponding temperature monitoring point; from the start of the circulating fluidized bed operation, the pre-processed bed temperature data is recorded in real time in the temperature line graph until the end of this operation;

[0063] Through the temperature line graph, the temperature change trends at each temperature monitoring point in the dense phase region during the operation of the circulating fluidized bed can be visually observed, as well as the temperature differences between different monitoring points.

[0064] Combined with the content in Steps 101 to 104:

[0065] By scientifically selecting temperature monitoring points, accurately placing thermocouple devices, strictly preprocessing bed temperature data, and real-time plotting the temperature line graph, the comprehensive and accurate monitoring of the temperature in the dense phase region of the circulating fluidized bed is achieved, providing strong data support for timely detecting combustion abnormalities, optimizing the combustion process, and improving the boiler operation efficiency.

[0066] Step Two: Obtain several indicators affecting the bed temperature; respectively fit the bed temperature influence functions for different temperature monitoring points when each indicator increases and decreases based on the control variable method and the least squares method; record and accumulate the stable time after each adjustment, and use the least squares method to fit the stable time functions for different temperature monitoring points when each indicator increases and decreases;

[0067] The said Step Two includes the following steps:

[0068] Step 201: Based on theoretical knowledge, obtain several indicators for adjusting the bed temperature, specifically including six indicators: coal feeding amount, primary air volume, secondary air volume, fuel particle size, return material amount, and slag discharge amount; and sequentially record them as E 1 to E 6 ;

[0069] Among them, the coal feeding amount refers to the amount of fuel fed into the furnace per unit time; the amount of coal feeding directly determines the magnitude of the combustion heat release in the dense phase region. When the coal feeding amount increases, the combustion heat release increases, and the bed temperature will rise; conversely, when the coal feeding amount decreases, the bed temperature will drop; the influence of the coal feeding amount on the bed temperature has hysteresis because it takes a certain time for the fuel particles to be completely burned and release heat after being put in;

[0070] The primary air volume refers to the air volume of the primary air fan sent to the air distribution plate at the bottom of the furnace, which mainly has two functions in the circulating fluidized bed boiler: one is as the fluidizing air to maintain the natural fluidized state of the bed material; the other is as part of the oxygen required for combustion; the adjustment of the primary air volume will simultaneously affect the fluidized state and combustion efficiency in the dense phase region. When the air volume increases, although more oxygen can be provided to support combustion, more heat will be carried away at the same time, resulting in a decrease in the bed temperature; conversely, when the air volume decreases, the fluidization effect may become poor, affecting the combustion efficiency, but the bed temperature will rise;

[0071] Secondary air volume refers to the air volume of the secondary fan sent into the combustion area in the upper part of the furnace. It is mainly used to strengthen the disturbance and mixing in the upper part of the furnace, make the fuel burn more fully, and reduce the furnace outlet temperature. When the secondary air volume increases, the combustion and heat transfer in the upper part of the furnace are strengthened, which may take away more heat, resulting in a decrease in the bed temperature in the dense phase area. However, the increase in secondary air volume also helps to improve the combustion efficiency in the entire furnace, thereby stabilizing or increasing the bed temperature to a certain extent.

[0072] Fuel particle size refers to the size of fuel particles. If the particles are too small, the coal will be blown to the dilute phase area by the primary wind as soon as it enters the furnace, and burn in the dilute phase area or the horizontal flue heating surface without causing the bed temperature to rise significantly. When the coal particle size is too large, the operator will often use a larger operating air volume to maintain the fluidization state of the material layer, otherwise the bed material will be stratified, and the bed layer will be partially or completely overheated and coked, which will delay the combustion time and reduce the bed temperature.

[0073] The return material volume refers to the volume of materials collected from the separator of the circulating fluidized bed and sent back to the furnace; these materials sent back to the furnace generally have a lower temperature than the materials in the furnace, thereby adjusting the bed temperature, that is, when the return material volume increases, the bed temperature in the dense phase zone will decrease, and when the return material volume decreases, the bed temperature in the dense phase zone will increase;

[0074] Slag discharge refers to the amount of ash discharged from the bottom of the furnace per unit time. The amount of slag discharge directly affects the bed thickness and bed material amount, and thus affects the bed temperature. If the slag discharge is too large, the bed thickness will decrease and the combustion will be complete, so the bed temperature will rise. On the contrary, if the slag discharge is too small, the bed thickness will increase and the combustion will be incomplete, so the bed temperature will drop.

[0075] Step 202: Based on theoretical knowledge and expert experience, standard values ​​of the above six indicators are obtained respectively, that is, standard values ​​of each indicator that can ensure the combustion efficiency in the bed layer when the circulating fluidized bed boiler is operating normally; and the bed temperature influence function at each temperature monitoring point is fitted for each indicator in turn, specifically:

[0076] The circulating fluidized bed is operated according to the standard values ​​of the six indicators; when the combustion in the bed of the circulating fluidized bed is stable (i.e., the bed temperature at each temperature monitoring point fluctuates within the set range for a period of time, and there is no significant abnormal rise and fall), an indicator E is selected from the six indicators to fit the bed temperature influence function and the stabilization time function. i , the values ​​of the other five indicators remain unchanged; within the allowed range, gradually increase or decrease the selected indicator E iThe value of

[0077] Based on multiple independent increases or decreases of the selected index E i The value of and respectively represent the value e of the selected index E i When increasing and decreasing, the bed temperature influence functions at each temperature monitoring point, where P represents the temperature monitoring point, and u and d respectively represent the increase and decrease of the value e of the selected index E i The value e of i The value e of i Increase and decrease, respectively represent the value e of the selected index E i When increasing and decreasing, the slopes of the temperature influence functions at the temperature monitoring point P respectively represent the value e of the selected index E i When increasing and decreasing, the intercepts of the temperature influence functions at the temperature monitoring point P;

[0078] Among them, the least squares fitting function is a mathematical optimization method. It finds the best fitting parameters by minimizing the sum of the squared residuals between the data points and the fitting function, so as to obtain a function that can most accurately describe the data trend;

[0079] After fitting functions for all the indexes, the bed temperature influence functions of all the indexes are obtained and

[0080] Step 203: Based on multiple independent increases or decreases of the selected index E i The value of i Record the time required for the combustion in the bed layer to become stable again after each adjustment; Accumulate these stable times after single adjustments to obtain the total stable time t after multiple adjustments; For example: When the value of the selected index E 1 is increased for the first time, the time t i required for the combustion at a certain temperature monitoring point to become stable again after this adjustment is obtained 2 ; When the value of the selected index E iThe total stabilization time t required to adjust the value to the value after the second increase is t = t 1 + t 2 ;

[0081] Using the least squares method for a linear function, that is, fitting the stabilization time function, to obtain and respectively represent the bed temperature influence functions at each temperature monitoring point when the selected index E i increases and decreases, where i respectively represent the slopes of the stabilization time functions at the temperature monitoring point P when the selected index E i increases and decreases,

[0082] respectively represent the intercepts of the stabilization time functions at the temperature monitoring point P when the selected index E i increases and decreases;

[0083] After fitting all the indexes into functions, the stabilization time functions of all indexes are obtained

[0084] Combined with the content in steps 201 to 203:

[0085] By systematically identifying multiple key indexes affecting the bed temperature and applying the control variable method and the least squares method, the influence functions of these indexes on the bed temperature at different temperature monitoring points when increasing and decreasing, as well as the corresponding stabilization time functions, are respectively fitted; this provides accurate mathematical model support for real-time adjustment of combustion parameters and optimization of the combustion process, helps to achieve rapid and stable control of the bed temperature, and further improves the combustion efficiency and operation stability of the circulating fluidized bed boiler.

[0085] Step 3: Real-time monitor the temperature changes at each temperature monitoring point of the circulating fluidized bed and compare them with the set normal temperature range; when an abnormal monitoring point is found, execute a single-monitoring-point or multi-monitoring-point adjustment strategy according to the number of abnormal monitoring points; the single-monitoring-point adjustment strategy determines the adjustment method and value by screening the bed temperature influence function, calculates the comprehensive temperature influence index and the comprehensive time influence index through the priority determination strategy, and comprehensively selects the best adjustment method; the multi-monitoring-point adjustment strategy determines whether all abnormal points can be adjusted to the normal temperature range under the maximum adjustment value in the common adjustment method by screening the common indexes and adjustment methods, and combines the single-monitoring-point adjustment strategy to comprehensively select the best adjustment method;

[0086] The steps in step 3 include the following steps:

[0087] Step 301: During the operation of the circulating fluidized bed, real-time monitor the temperature changes at each temperature monitoring point in the line graph, and set each bed layer (i.e., in the dense phase region) according to theoretical knowledge and expert experience and the normal temperature range T at height h 1 、T 2 、T 3 ;

[0088] Step 302: Compare the temperature at each temperature monitoring point monitored in real time with the corresponding normal temperature range. Among them, the temperatures at the 4 temperature monitoring points at height in the dense phase area are compared with the normal temperature range T , and so on; 1 If the temperature at any temperature monitoring point other than the abnormal monitoring point exceeds the corresponding normal temperature range, mark this temperature monitoring point as an abnormal monitoring point and execute the judgment strategy;

[0089] Among them, the judgment strategy: judge the number n of abnormal monitoring points at this time. If n = 1, execute the single monitoring point adjustment strategy; otherwise, execute the multi-monitoring point adjustment strategy;

[0090] Among them, the single monitoring point adjustment strategy: further judge the magnitude relationship between the temperature at this abnormal monitoring point and the corresponding normal temperature range. If the temperature at this abnormal monitoring point exceeds the upper limit of the corresponding normal temperature range, it means that the temperature at this abnormal monitoring point is higher than the normal range; screen out all the bed temperature influence function corresponding indexes E

[0091] whose slopes are less than 0. These bed temperature influence functions will increase or decrease with the index E or and decrease the bed temperature; if the temperature at this abnormal monitoring point is lower than the lower limit of the corresponding normal temperature range, it means that the temperature at this abnormal monitoring point is lower than the normal range; screen out all the bed temperature influence function corresponding indexes E i whose slopes are greater than 0. These bed temperature influence functions will increase or decrease with the index E i and increase the bed temperature; determine the priority strategy for the screened indexes; or Among them, the priority determination strategy: determine the adjustment method (increase or decrease) and adjustment value (the value of increase or decrease) for the screened indexes in turn. For example, if it is determined that the index E i is to be decreased and the bed temperature can be lowered, the adjustment value of the index E i needs to be determined. If the abnormal monitoring point is A

[0092] 1 , then according to the fitted bed temperature influence function: max 1 1 , the adjustment value e 1 of the index E 1 can be obtained, that is, the index E 1 ​1 Reduce e 1 ;

[0093] After determining the adjustment method and adjustment value, calculate the temperature change at all other temperature monitoring points after adjustment according to the adjustment method and adjustment value; and judge whether the adjusted temperature at all other temperature monitoring points exceeds the corresponding normal temperature range. If the adjusted temperature at any temperature monitoring point exceeds the corresponding normal temperature range, delete the adjustment method; otherwise, record the adjustment method in the set of candidate adjustment methods;

[0094] Based on the relationship between the adjusted temperature at each of the remaining temperature monitoring points and the median of the corresponding normal temperature range, calculate the comprehensive temperature influence index of each adjustment method in the set of candidate adjustment methods. For example, for temperature monitoring point A 2 , the temperature after adjustment by the adjustment method is Judge and the relationship with the median mid{T 1} of the corresponding normal temperature range T 1 , and If then the temperature influence index of this adjustment method for temperature monitoring point A 2 is If then the temperature influence index of this adjustment method for this temperature monitoring point is Accumulate the temperature influence indices of this adjustment method for each of the remaining temperature monitoring points to obtain the comprehensive temperature influence index of this adjustment method; where max{T 1} represents the maximum value in the normal temperature range T 1 , that is, the upper limit of the normal temperature range T 1 ; min{T 1} represents the minimum value in the normal temperature range T 1 , that is, the lower limit of the normal temperature range T 1 ;

[0095] Based on the magnitude relationship between the adjusted stabilization time at each of the remaining temperature monitoring points and the adjusted stabilization time at the abnormal monitoring point, calculate the comprehensive time influence index of each adjustment method in the set of candidate adjustment methods. For example, for abnormal monitoring point A 1 , the stabilization time after adjustment by the adjustment method is For temperature monitoring point A 2 , the stabilization time after adjustment is Judge and the relationship with , if then this adjustment method for temperature monitoring point A2 Time impact index If then this adjustment method for temperature monitoring point A 2 Time impact index Accumulate the time impact indices of this adjustment method for each of the remaining temperature monitoring points to obtain the comprehensive time impact index of this adjustment method;

[0096] Add the comprehensive temperature impact index and the comprehensive time impact index of each adjustment method in the set of candidate adjustment methods, and sort all adjustment methods in descending order according to the sum, and select the adjustment method ranked first to adjust the bed temperature;

[0097] Among them, the multi-monitoring point adjustment strategy: based on the single-monitoring point adjustment strategy, according to the magnitude relationship between the temperature at each abnormal monitoring point and the corresponding normal temperature range, respectively screen out the indicators for adjusting the bed temperature at each abnormal monitoring point, and determine the adjustment method and adjustment value for the screened indicators;

[0098] Screen out the common indicators and adjustment methods (the indicators and adjustment methods are the same) of multiple abnormal monitoring points, and calculate the adjustment value of each abnormal monitoring point under this adjustment method. Judge whether the temperatures at all abnormal monitoring points can be adjusted to the corresponding normal temperature range when adjusting according to the maximum adjustment value; if so, continue to judge whether the adjusted temperatures at all the remaining temperature monitoring points exceed the corresponding normal temperature range under this adjustment method and adjustment value. If the adjusted temperatures at all the remaining temperature monitoring points do not exceed the corresponding normal temperature range, then adjust the bed temperature at each abnormal monitoring point according to this adjustment method and adjustment value; if the adjusted temperature at any temperature monitoring point exceeds the corresponding normal temperature range, then perform the single-monitoring point adjustment strategy in turn according to the magnitude of the value by which the abnormal monitoring point exceeds the corresponding normal temperature range to select the best adjustment method.

[0099] Combined with the content in steps 301 to 302:

[0100] This design can timely detect and handle abnormal bed temperature by real-time monitoring the temperature changes of each temperature monitoring point in the circulating fluidized bed and comparing with the set normal temperature range, effectively avoiding boiler operation problems caused by too high or too low bed temperature; for abnormal monitoring points, the design proposes a single-monitoring point adjustment strategy and a multi-monitoring point adjustment strategy. These two strategies can flexibly select adjustment methods and values according to different abnormal situations to ensure that the bed temperature quickly and accurately returns to the normal range, thereby improving the combustion efficiency of the boiler;

[0101] In the formulation of the adjustment strategy, factors such as the bed temperature influence function, the priority determination strategy, the comprehensive temperature influence index, and the comprehensive time influence index are fully considered; by screening the indicators corresponding to the bed temperature influence function and determining their adjustment methods and values, a design is made to accurately find the factors that have the greatest influence on the bed temperature and make targeted adjustments; by calculating the comprehensive temperature influence index and the comprehensive time influence index, a design is made to comprehensively evaluate the overall influence of different adjustment methods on the bed temperature, so as to select the best adjustment method; this refined adjustment strategy not only improves the control accuracy of the boiler but also enhances the adaptability of the boiler to different operating conditions, ensuring the stable operation of the boiler.

[0102] Reference Figure 3 , the present invention also provides a real-time control system applied to the combustion of a circulating fluidized bed boiler, including:

[0103] A data acquisition module places thermocouple devices at several temperature monitoring points in the circulating fluidized bed layer to monitor the bed temperature at each temperature monitoring point in real time during the operation of the circulating fluidized bed, and records the obtained bed temperature data in a temperature broken line graph after preprocessing.

[0104] An index determination module obtains several indexes for adjusting the bed temperature based on theoretical knowledge, specifically including six indexes: coal feeding amount, primary air volume, secondary air volume, fuel particle size, return material amount, and slag discharge amount.

[0105] A function fitting module includes a bed temperature influence function fitting unit and a stable time function fitting unit; the bed temperature influence function fitting unit respectively fits the bed temperature influence functions of each index when increasing and decreasing for different temperature monitoring points based on the control variable method and the least square method; the stable time function fitting unit records and accumulates the stable time after each adjustment, and uses the least square method to fit the stable time functions of each index when increasing and decreasing for different temperature monitoring points.

[0106] An adjustment method determination module includes a single monitoring point adjustment unit and a multi-monitoring point adjustment unit; the single monitoring point adjustment unit is used to execute the single monitoring point adjustment strategy when it is determined that the number of abnormal monitoring points is single, determine the adjustment method and value by screening the bed temperature influence function, calculate the comprehensive temperature influence index and the comprehensive time influence index through the priority determination strategy, and comprehensively select the best adjustment method; the multi-monitoring point adjustment unit is used to, when it is determined that the number of abnormal monitoring points is multiple, judge whether all abnormal points can be adjusted to the normal temperature range under the maximum adjustment value in the common adjustment method by screening the common indexes and adjustment methods, and combine the single monitoring point adjustment strategy to comprehensively select the best adjustment method.

[0107] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present invention are generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer storage medium or transmitted through a computer storage medium.

[0108] The computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center by wire (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wirelessly (e.g., infrared, wireless, microwave, etc.). The computer storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server or data center that includes one or more integrated available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid state disk (SSD)), etc.

[0109] As described above, the above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A real-time control method for combustion of a circulating fluidized bed boiler, characterized in that: include: Thermocouple devices are placed at several temperature monitoring points in the bed layer of the circulating fluidized bed to monitor the bed temperature at each temperature monitoring point in real time when the circulating fluidized bed is running, and the acquired bed temperature data is preprocessed and recorded in a temperature line graph; Obtain several indicators that affect bed temperature; Based on the control variable method and the least square method, the bed temperature influence function at different temperature monitoring points is fitted when each indicator increases and decreases; the stable time after each adjustment is recorded and accumulated, and the least square method is used to fit the stable time function at different temperature monitoring points when each indicator increases and decreases; Monitor the temperature changes of each temperature monitoring point of the circulating fluidized bed in real time and compare it with the set normal temperature range; when an abnormal monitoring point is found, implement a single monitoring point or multiple monitoring point adjustment strategy according to the number of abnormal monitoring points; The single monitoring point adjustment strategy determines the adjustment method and value by screening the bed temperature influence function, calculates the comprehensive temperature influence index and the comprehensive time influence index through the priority determination strategy, and comprehensively selects the best adjustment method; The multi-monitoring point adjustment strategy screens common indicators and adjustment methods to determine whether all abnormal points can be adjusted to the normal temperature range under the maximum adjustment value in the common adjustment method, and combines the single monitoring point adjustment strategy to comprehensively select the best adjustment method.

2. A real-time control method for combustion in a circulating fluidized bed boiler as claimed in claim 1, characterized in that: Get the height h of the dense phase zone in the circulating fluidized bed layer and and the candidate layer at height h as the temperature monitoring point; Four target points are randomly selected on the candidate layer at the height as the temperature monitoring points of the candidate layer. It is required that the following relationship exists between any temperature monitoring point and the other three temperature monitoring points: Among the other three temperature monitoring points, (1) There are two temperature monitoring points with the same distance from the selected temperature monitoring point; (2) The line between the temperature monitoring points other than the two temperature monitoring points in (1) and the selected temperature monitoring point passes through the center of the circle of the corresponding candidate layer; Will be in The temperature monitoring points selected on the candidate layer at the height are translated upwards Height and Height, respectively Temperature monitoring points selected at height and on the alternative layer at height h.

3. A real-time control method for combustion in a circulating fluidized bed boiler as claimed in claim 2, characterized in that: The several indices affecting the bed temperature include coal feed rate, primary air volume, secondary air volume, fuel particle size, return material volume and slag discharge volume, a total of 6 indices, and are recorded as E1 to E6 in the above order; The circulating fluidized bed is operated according to the standard values ​​of the six indicators; when the combustion in the bed of the circulating fluidized bed is stable, an indicator E is selected from the six indicators to fit the bed temperature influence function and the stable time function. i , the values ​​of the other five indicators remain unchanged; within the allowed range, gradually increase or decrease the selected indicator E i and when the combustion in the bed of the circulating fluidized bed stabilizes again, record the bed temperature at each temperature monitoring point and the time from adjusting the index to stabilizing the combustion in the bed again; the allowable range is the reasonable range of the index value without affecting the safe and stable operation of the boiler, which is determined based on historical operating experience.

4. A real-time control method for combustion in a circulating fluidized bed boiler as claimed in claim 3, characterized in that: Based on multiple independent increases or decreases of the selected indicator E i The value of and the corresponding bed temperature value T at each temperature monitoring point after each adjustment are used to fit the bed temperature influence function using the least squares method to obtain and Respectively represent the selected index E i The value of e i When the temperature increases and decreases, the bed temperature at each temperature monitoring point affects the function, where P represents the temperature monitoring point, u and d represent the selected index E i The value of e i The increase and decrease of Respectively represent the selected index E i When increasing or decreasing, the slope of the temperature influence function at the temperature monitoring point P is, Respectively represent the selected index E i The intercept of the temperature influence function at the temperature monitoring point P when increasing or decreasing.

5. A real-time control method for combustion in a circulating fluidized bed boiler as claimed in claim 4, characterized in that: Based on multiple independent increases or decreases of the selected indicator E i The value of the bed is recorded, and the time required for the combustion in the bed to stabilize again after each adjustment is recorded; the stabilization time after these single adjustments is accumulated to obtain the total stabilization time t after multiple adjustments; The least squares method is used to fit the stable time function and obtain and Respectively represent the selected index E i The value of e i The bed temperature influence function at each temperature monitoring point when increasing and decreasing, where: Respectively represent the selected index E i When increasing or decreasing, the slope of the stable time function at the temperature monitoring point P is, Respectively represent the selected index E i The intercept of the stable time function at the temperature monitoring point P when increasing or decreasing.

6. A real-time control method for combustion in a circulating fluidized bed boiler as claimed in claim 5, characterized in that: During the operation of the circulating fluidized bed, the temperature changes at each temperature monitoring point in the line graph are monitored in real time; the temperature at each temperature monitoring point monitored in real time is compared with the corresponding normal temperature range T 1 , T 2 , T 3 Real-time comparison, where T 1 , T 2 , T 3 Indicates the dense phase region and the normal temperature range at height h; If the temperature at any temperature monitoring point other than the abnormal monitoring point is detected to be beyond the corresponding normal temperature range, the temperature monitoring point is marked as an abnormal monitoring point and the judgment strategy is executed; The judgment strategy is used to judge the number n of abnormal monitoring points at this time. If n=1, a single monitoring point adjustment strategy is executed; otherwise, a multi-monitoring point adjustment strategy is executed.

7. A real-time control method for combustion in a circulating fluidized bed boiler as claimed in claim 6, characterized in that: The single monitoring point adjustment strategy is specifically as follows: Determine the relationship between the temperature at the abnormal monitoring point and the corresponding normal temperature range. If the temperature at the abnormal monitoring point exceeds the upper limit of the corresponding normal temperature range, it means that the temperature at the abnormal monitoring point is higher than the normal range; filter out all slopes or The index E corresponding to the bed temperature influence function less than 0 i ; If the temperature at the abnormal monitoring point is lower than the lower limit of the corresponding normal temperature range, it means that the temperature at the abnormal monitoring point is lower than the normal range; filter out all slopes or The index E corresponding to the bed temperature influence function greater than 0 i ; Develop a priority strategy for the selected indicators.

8. A real-time control method for combustion in a circulating fluidized bed boiler as claimed in claim 7, characterized in that: The priority determination strategy is used to select the best adjustment method, including: The adjustment method and adjustment value are determined for the screened indicators in turn; after the adjustment method and adjustment value are determined, the temperature change at all other temperature monitoring points after adjustment according to the adjustment method and adjustment value is calculated; and it is determined whether the adjusted temperature at all other temperature monitoring points exceeds the corresponding normal temperature range. If the adjusted temperature at any temperature monitoring point exceeds the corresponding normal temperature range, the adjustment method is deleted; otherwise, the adjustment method is recorded in the set of adjustment methods to be selected.

9. A real-time control method for combustion in a circulating fluidized bed boiler as claimed in claim 8, characterized in that: The prioritization strategy also includes: Based on the relationship between the adjusted temperature at each of the remaining temperature monitoring points and the median of the corresponding normal temperature range, the comprehensive temperature impact index of each adjustment method in the candidate adjustment method set is calculated; based on the relationship between the adjusted stabilization time at each of the remaining temperature monitoring points and the adjusted stabilization time at the abnormal monitoring point, the comprehensive time impact index of each adjustment method in the candidate adjustment method set is calculated; The comprehensive temperature impact index and the comprehensive time impact index of each adjustment method in the candidate adjustment method set are added together, and all adjustment methods are sorted in descending order after the addition, and the adjustment method ranked first is selected to adjust the bed temperature.

10. A real-time control method for combustion in a circulating fluidized bed boiler according to claim 9, characterized in that: The multi-monitoring point adjustment strategy is specifically as follows: Based on the single monitoring point adjustment strategy, according to the size relationship between the temperature at each abnormal monitoring point and the corresponding normal temperature range, the indicators used to adjust the bed temperature at each abnormal monitoring point are screened out respectively, and the adjustment method and adjustment value of the screened indicators are determined; Filter out the common indicators and adjustment methods of multiple abnormal monitoring points, and calculate the adjustment value of each abnormal monitoring point under the adjustment method, and determine whether the temperature at all abnormal monitoring points can be adjusted to the corresponding normal temperature range when adjusting according to the maximum adjustment value; If yes, continue to judge whether the adjusted temperatures at all other temperature monitoring points exceed the corresponding normal temperature range under the adjustment method and adjustment value. If the adjusted temperatures at all other temperature monitoring points do not exceed the corresponding normal temperature range, adjust the bed temperature at each abnormal monitoring point according to the adjustment method and adjustment value; if the adjusted temperature at any temperature monitoring point exceeds the corresponding normal temperature range, then according to the value of the abnormal monitoring point exceeding the corresponding normal temperature range, perform single monitoring point adjustment strategies in turn to select the best adjustment method.

11. A real-time control system for circulating fluidized bed boiler combustion, characterized in that: include: The data acquisition module places thermocouple devices at several temperature monitoring points in the circulating fluidized bed layer to monitor the bed temperature at each temperature monitoring point in real time when the circulating fluidized bed is running, and records the acquired bed temperature data in a temperature line graph after preprocessing; The indicator determination module obtains several indicators for adjusting the bed temperature based on theoretical knowledge, including coal feed rate, primary air volume, secondary air volume, fuel particle size, return material volume and slag discharge volume, a total of 6 indicators; The function fitting module includes a bed temperature influence function fitting unit and a stable time function fitting unit; the bed temperature influence function fitting unit fits the bed temperature influence function at different temperature monitoring points when each indicator increases and decreases based on the control variable method and the least square method; the stable time function fitting unit records and accumulates the stable time after each adjustment, and uses the least square method to fit the stable time function at different temperature monitoring points when each indicator increases and decreases; An adjustment mode determination module includes a single monitoring point adjustment unit and a multi-monitoring point adjustment unit; The single monitoring point adjustment unit is used to execute the single monitoring point adjustment strategy when it is judged that the number of abnormal monitoring points is single, determine the adjustment method and value by screening the bed temperature influence function, calculate the comprehensive temperature influence index and the comprehensive time influence index through the priority determination strategy, and comprehensively select the best adjustment method; the multi-monitoring point adjustment unit is used to determine whether all abnormal points can be adjusted to the normal temperature range under the maximum adjustment value in the public adjustment method by screening the public indicators and adjustment methods when it is judged that the number of abnormal monitoring points is multiple, and comprehensively select the best adjustment method in combination with the single monitoring point adjustment strategy.

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