A two-dimensional temperature field combustion control method and system

Abstract

The application discloses a two-dimensional temperature field combustion control method and system, which comprises a plurality of burners arranged in a main combustion zone and a plurality of secondary air nozzles corresponding to the burners; each burner is connected with a primary air powder system through a coal powder pipeline; each secondary air nozzle is connected with a secondary air box through a secondary air pipeline, and a plurality of burn-off air nozzles are arranged in a burn-off zone; and a two-dimensional temperature field measuring device arranged in a grid is arranged in a horizontal cross section of a flue above the burn-off zone. The application adopts the concept of "precise feedforward control", and independently and simply controls the main combustion zone and the burn-off zone of the coal-fired boiler. In the case that the coal powder flow of each burner in the main combustion zone is the same and the air-coal ratio is the same, only the flow and the swing angle of the burn-off air nozzles in the burn-off zone corresponding to the two-dimensional temperature field need to be adjusted according to the temperature distribution of the two-dimensional temperature field, so that the flame center in the furnace of the coal-fired boiler is kept at the geometric center position of the flue.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optimized control of coal-fired boilers, and in particular to a two-dimensional temperature field combustion control method and system. BACKGROUND

[0002] CN 110195860 A discloses a boiler four-corner tangential circle combustion flame center offset adjustment method. The prior art indirectly determines the temperature position of the flame center by comparing the difference between the average temperature of the outlet flue gas and the average temperature of multiple measuring points of the outer wall, so as to adjust the primary air and the secondary air to change the flame center position. However, the prior art does not specifically explain how to adjust the flame center position by the primary air and the secondary air.

[0003] Similarly, CN 114857578 A discloses a method for improving the thermal state research of flame center deflection of a four-corner tangential boiler. The prior art believes that the flame center deflection is caused by the fact that the combustion parameters are not optimized due to improper position matching of the air volume, horizontal angle, and main burner swing angle of the three kinds of air. As long as the optimal matching parameters of the three kinds of air are determined according to the outlet temperature field and oxygen field, the combustion can be more uniform, and the probability of flame center deflection can be reduced. Thus, the prior art focuses on calibrating the air volume of primary air, secondary air, and overfire air under different working conditions, and determining the optimal combustion state by comparing the outlet temperature field and oxygen field under various working conditions. When specifically explaining the measurement of the outlet temperature field and oxygen field, the prior art uses 24 evenly arranged flue holes to collect flue gas temperature, flue gas oxygen content, and fly ash combustible along the flue width section. The deviation of the measurement value of each point from the average value is not more than 5%, which is considered as good combustion, and there is no flame center deflection. It can be seen that the prior art also determines the flame center based on an average indirect calculation. The actual position of the flame center is determined according to the temperature difference, and the distribution of the measurement points will affect the calculation result. At the same time, if the deviation exceeds 5%, the primary air, secondary air, overfire air, and various swing angles need to be adjusted until the deviation is less than 5%. However, since the temperature field and oxygen field are obtained based on average calculation, it cannot be directly determined whether the poor combustion is caused by excessive air volume in a certain direction or insufficient air volume in the opposite direction, or by the directional error of the swing angle of a certain air port. Thus, when adjusting the technical parameters, the prior art adjusts the air volume or swing angle of all burners uniformly, for example, uniformly increasing or decreasing the air door opening by 20%, or uniformly increasing or decreasing the swing angle of all air ports by 5 degrees. Thus, the prior art actually optimizes the combustion state, rather than directly adjusting the position of the flame center. At the same time, the average fuzzy processing of the prior art cannot determine the poor combustion components, is difficult to meet the requirements of rapid load variation control, and can cause poor boiler operation economy, high flue gas emission pollutants, and boiler heating surface coking and slagging. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a two-dimensional temperature field combustion control method and system to reduce or avoid the problems mentioned above.

[0005] To solve the above technical problems, the application provides a two-dimensional temperature field combustion control method for controlling the combustion of a coal-fired boiler through a two-dimensional temperature field, wherein the main combustion zone of the coal-fired boiler is provided with a plurality of burners and a secondary air nozzle corresponding to each burner; the burnout zone of the coal-fired boiler is provided with a plurality of burnout air nozzles; the horizontal cross section of the flue above the burnout zone is provided with a two-dimensional temperature field measuring device arranged in a grid.

[0006] Preferably, the step A further comprises: adjusting the coal powder flow in each coal powder pipeline corresponding to each burner to be substantially the same according to the measured primary air flow and coal powder flow in each coal powder pipeline.

[0007] Preferably, the step A further comprises: adjusting the opening degree of the secondary air damper of the secondary air nozzle of each burner according to the measured secondary air flow of each secondary air nozzle to make the air-coal ratio of each burner substantially the same on the premise that the coal powder flow in each coal powder pipeline corresponding to each burner is substantially the same.

[0008] Preferably, a plurality of two-dimensional temperature field measuring devices are uniformly arranged around the flue above the burnout zone, and the measurement paths of the plurality of two-dimensional temperature field measuring devices intersect with each other to form a plurality of grid intersection points, and the temperature at each grid intersection point position constitutes the two-dimensional temperature field.

[0009] The application further provides a two-dimensional temperature field combustion control system, which comprises a plurality of burners and a secondary air nozzle corresponding to each burner arranged in the main combustion zone of the coal-fired boiler; each burner is connected with a primary air powder system through a coal powder pipeline; each secondary air nozzle is connected with a secondary air wind box through a secondary air pipeline, characterized in that the burnout zone of the coal-fired boiler is provided with a plurality of burnout air nozzles; and the horizontal cross section of the flue above the burnout zone is provided with a two-dimensional temperature field measuring device arranged in a grid.

[0010] Preferably, each pulverized coal pipeline is provided with a pulverized coal flow measuring sensor, a primary air flow sensor and a primary air-pulverized coal adjusting valve; each secondary air nozzle is provided with a secondary air flow sensor and a secondary air damper in the corresponding secondary air pipeline; the pulverized coal flow measuring sensor, the primary air flow sensor, the primary air-pulverized coal adjusting valve, the secondary air flow sensor and the secondary air damper are connected to the main combustion zone control module through control cables.

[0011] Preferably, a secondary air total damper is arranged in the secondary air main pipeline connecting the secondary air blast box and each secondary air pipeline, and the secondary air total damper is connected to the main combustion zone control module through a control cable.

[0012] Preferably, each overfire air nozzle is connected to the secondary air blast box through an overfire air pipeline, and each overfire air nozzle is provided with an overfire air flow sensor and an overfire air damper in the corresponding overfire air pipeline; each overfire air nozzle is provided with an angle adjustment device and a driving link, and the angle adjustment device can drive the driving link to move according to the instruction, thereby deflecting the overfire air nozzle by the angle; the angle adjustment device, the overfire air flow sensor, the overfire air damper and the two-dimensional temperature field measuring device are connected to the overfire zone control module through control cables.

[0013] Preferably, the overfire air nozzles are uniformly arranged on the front wall and the back wall of the coal-fired boiler, and include one or more layers of longitudinally aligned overfire air nozzles.

[0014] Preferably, a plurality of two-dimensional temperature field measuring devices are uniformly arranged around the flue at the top of the overfire zone, and the measurement paths of the plurality of two-dimensional temperature field measuring devices intersect with each other to form a plurality of grid intersection points, and the temperature at each grid intersection point constitutes the two-dimensional temperature field.

[0015] The present application adopts the concept of "precise front feedback control" to independently and simply control the main combustion zone and the overfire zone of the coal-fired boiler. In the case that the pulverized coal flow of each burner in the main combustion zone is the same and the air-pulverized coal ratio is the same, only the flow and the angle of the overfire air nozzles corresponding to the positions of the two-dimensional temperature field in the overfire zone need to be adjusted according to the temperature distribution of the two-dimensional temperature field, so that the flame center in the furnace of the coal-fired boiler is kept at the geometric center position of the flue. BRIEF DESCRIPTION OF DRAWINGS

[0016] The following drawings are only intended to illustrate and explain the present application, and do not limit the scope of the present application.

[0017] wherein, Figure 1 The figure shows a structure diagram of a two-dimensional temperature field combustion control system according to an embodiment of the present application.

[0018] Figure 2A layout schematic of an overfire air nozzle according to one embodiment of the present application is shown.

[0019] Figure 3 A layout schematic of a two-dimensional temperature field measurement device according to one embodiment of the present application is shown. DETAILED DESCRIPTION

[0020] In order to have a clearer understanding of the technical features, objects and effects of the present application, the specific embodiments of the present application will be described with reference to the accompanying drawings.

[0021] The existing coal-fired boiler combustion control cannot be accurately regulated due to technical limitations, especially the location of insufficient combustion cannot be determined, and only the coal supply, primary air and secondary air flow of all burners can be generally adjusted, so even if accurate regulation can be achieved, individual burner corresponding parameters cannot be adjusted and controlled individually.

[0022] Therefore, the present application proposes an optimized two-dimensional temperature field combustion control method and system, as shown in Figure 1 The general idea of the optimization method of the present application is to divide the entire coal-fired boiler 1 combustion area into a main combustion zone 100 and a burnout zone 200, and control them relatively independently, based on the concept of "accurate feedforward control".

[0023] Specifically, in the main combustion zone 100, based on the air-coal ratio control of a single burner 31, starting from the root of affecting the combustion of the coal-fired boiler 1, by measuring the primary air flow and coal mass flow entering each burner 31, the secondary air flow of the single burner 31 is adjusted, that is, the air-coal ratio of the single burner 31 is adjusted, so that each burner 31 is operated under the best operating condition closest to the design. The inventors believe that when the coal flow and air-coal ratio of each burner 31 in the main combustion zone are the same, the burner has reached the best operating condition, and under the condition that the combustion load is determined, subsequent adjustment is not required.

[0024] After the main combustion zone 100 is regulated, the operating parameters of the main combustion zone 100 are kept unchanged, and only the operating parameters of the burnout zone 200 are adjusted independently.

[0025] Specifically, in the burnout zone 200, by detecting the temperature distribution of the two-dimensional temperature field above the burnout zone 200 in real time, the flow and swing angle of the overfire air nozzle 61 corresponding to the two-dimensional temperature field in the burnout zone 200 are adjusted, so that the combustion in the furnace is more uniform and sufficient, the coal combustion efficiency is improved, the coal consumption and pollutant emissions are reduced, and the problems such as coking and slagging of the boiler heating surface are reduced.

[0026] The division of the main combustion zone and the burnout zone is described in many prior art documents, and some documents also consider that there is a re-combustion zone between the main combustion zone and the burnout zone. Therefore, the division of the relevant regions is a known technology and is not a concept created by the present application. The present application only innovates in the layout and control method in the known main combustion zone and burnout zone.

[0027] More specifically, as shown in the figure, based on the above optimization method, the present application proposes a two-dimensional temperature field combustion control system, which includes a plurality of burners 31 arranged in the main combustion zone 100 of the coal-fired boiler 1 and a plurality of secondary air nozzles 41 corresponding to each burner 31; each burner 31 is connected to the primary air pulverizing system 3 through a coal powder pipeline 30; each secondary air nozzle 41 is connected to the secondary air box 4 through a secondary air pipeline 40. The primary air pulverizing system 3 includes a conventional pulverizing system composed of multiple coal mills and a primary air box (not shown in the figure), and the primary air pulverizing system 3 delivers the prepared coal powder to the corresponding burners 31 through the primary air and multiple coal powder pipelines 30.

[0028] Unlike the prior art, the present application further provides a plurality of burnout air nozzles 61 in the burnout zone 200 of the coal-fired boiler 1 and a two-dimensional temperature field measuring device 71 above the burnout zone 200, and adjusts the flow rate and swing angle of the burnout air nozzles 61 corresponding to the positions of the corresponding grid nodes according to the temperature distribution at the grid nodes in the horizontal cross section perpendicular to the flue measured by the two-dimensional temperature field measuring device 71, so that the temperature distribution of the two-dimensional temperature field at the furnace outlet is more uniform.

[0029] Specifically, in an ideal state, the two-dimensional temperature field distribution in the horizontal cross section above the burnout zone 200 should be that the temperature at the geometric center of the horizontal cross section is the highest, the temperatures on the concentric circles with the same radius around the geometric center are basically equal, and the temperature decreases gradually with the increase of the radius. If the combustion is uneven, the two-dimensional temperature field distribution does not comply with the above ideal distribution rule. For example, if the highest temperature position deviates to the left of the geometric center, the swing angle and air volume of the burnout air nozzles 61 corresponding to the left position can be adjusted to "push" the highest temperature position towards the geometric center; or the swing angle and air volume of the burnout air nozzles 61 corresponding to the right position can be adjusted to "pull" the highest temperature position towards the geometric center; or both directions are adjusted simultaneously, and the "push-pull" combination is adjusted.

[0030] The two-dimensional temperature field measuring device 71 can adopt any system, method or device available in the prior art for obtaining a two-dimensional temperature field. For example, CN 1141513 C discloses a method for measuring the radiation energy and temperature field of a boiler combustion and controlling the combustion and a system thereof, which focuses on the measurement and processing of the temperature field, and the same or similar method and system can be adopted in the present application. Similarly, CN 1069960 C discloses a method for detecting the temperature distribution of a boiler furnace combustion and a device thereof, which can detect the distribution of a two-dimensional flame temperature field in real time through a flame image, and the same or similar method and device can be adopted in the present application to obtain the two-dimensional temperature field required in the present application.

[0031] It should be noted that the prior art obtains the vertical flame temperature field in the furnace, which needs to be improved to measure the two-dimensional temperature field in the horizontal section for use in the present application. The reason why the present application adopts the horizontal two-dimensional temperature field is that the combustion control in the present application adopts independent adjustment in different zones. After the main combustion zone 100 is adjusted to the optimal air-coal ratio through the combustion load, the combustion is already in the optimal state, and the subsequent burnout zone 200 is independently adjusted, without the need to adjust the combustion parameters of the main combustion zone. Therefore, when the parameters of the burnout zone 200 are adjusted according to the two-dimensional temperature field, the vertical height of the flame center will not change, and thus only the horizontal position of the flame center needs to be adjusted according to the horizontal temperature field, which can greatly simplify the measurement of the two-dimensional temperature field, facilitate targeted independent adjustment and control, improve the response speed of real-time detection, feedback and control, and adapt to the flexible control requirements of rapid load change.

[0032] Figure 2 A layout schematic of the burnout air injection ports according to one specific embodiment of the present application is shown, which shows the cross-sectional schematic of the coal-fired boiler 1 in Figure 1 In the specific embodiment shown in the figure, the burnout air injection ports 61 are uniformly arranged on the front wall 11 and the back wall 12 of the coal-fired boiler, including one or more layers of multiple burnout air injection ports 61 arranged in longitudinal alignment. In the specific embodiment shown in Figure 1 , a total of two layers of burnout air injection ports 61 are shown, the burnout air injection ports 61 in each layer are located in the same plane, and the burnout air injection ports 61 in the upper and lower two layers are arranged in longitudinal alignment in pairs to form a group, and a total of 8 groups of burnout air injection ports 61 are formed in the longitudinal direction. In the specific embodiment shown in Figure 2 , each layer contains 8 burnout air injection ports 61, of which 4 groups of burnout air injection ports 61 are uniformly arranged on the front wall 11, and 4 groups of burnout air injection ports 61 are also uniformly arranged on the back wall 12, and the burnout air injection ports 61 on the front wall 11 and the back wall 12 are also arranged in transverse alignment in pairs.

[0033] The concepts of front wall and back wall are conventional terms in the field, and are relative to the distance from the burner 31. The same side of the burner 31 is the front wall, and the opposite side of the burner 31 is the back wall. Since the burner 31 is usually arranged on the front wall, the pulverized coal is sprayed towards the back wall, and the flame center will not deviate left and right due to the mass of the pulverized coal, the air volume, the angle of the tuyere, and other reasons. Therefore, the uniform arrangement of the overfire air nozzles 61 on the front wall 11 and the back wall 12 can reduce the control difficulty and simplify the control method.

[0034] Figure 3 The two-dimensional temperature field measurement device corresponding to the position of the overfire air nozzle is shown in FIG. 6. Figure 2 The layout of the two-dimensional temperature field measurement device corresponding to the position of the overfire air nozzle is shown in FIG. 6. Figure 1 In the specific embodiment shown in the figure, the two-dimensional temperature field measurement device 71 is arranged in a grid in the horizontal cross-section of the flue above the burnout zone 200. Specifically, a plurality of two-dimensional temperature field measurement devices 71 are uniformly arranged on the periphery of the flue above the burnout zone 200, and the measurement paths of the plurality of two-dimensional temperature field measurement devices 71 intersect with each other to form a plurality of grid intersection points. The measured temperature at each grid intersection point constitutes the two-dimensional temperature field. More specifically, as shown in the figure, two two-dimensional temperature field measurement devices 71 are arranged on the front wall 11 of the coal-fired boiler 1, and two two-dimensional temperature field measurement devices 71 are also arranged on the back wall 12. The two-dimensional temperature field measurement devices 71 on the front wall 11 and the back wall 12 are arranged at intervals. Similarly, two two-dimensional temperature field measurement devices 71 are also arranged on the left wall and the right wall, respectively, and the two-dimensional temperature field measurement devices 71 on the left wall and the right wall are also arranged at intervals.

[0035] In one embodiment, the two-dimensional temperature field measuring device 71 can employ infrared optical pyrometers (for example, EUtech Scientific Engineering GmbH model GT-III or FT-III infrared optical pyrometers from Germany), each of which is both a transmitter and a receiver. The infrared optical pyrometer is based on the strong infrared radiation characteristics of CO2, and according to the Stefan-Boltzmann law, the total radiant heat power emitted from a surface is proportional to the fourth power of its absolute temperature, establishing a correspondence between the gas temperature and the radiation value, so that the flue gas temperature can be measured. Therefore, when the radiation value on a given length path is measured by the optical pyrometer, the integral average temperature on that length path can be obtained. When different path lengths are given, the corresponding radiation values and integral average temperatures can be obtained. In this way, the temperature at the intersection of the optical paths of each optical pyrometer can be calculated using a tomographic imaging algorithm similar to medical tomography. Through mathematical interpolation, the temperature value at each point in each grid region can be obtained. In this way, the temperature value information (position, temperature value) of the entire measured cross section can be obtained. Thus, using a data software processing system, the position of the center of the furnace flame can be accurately determined. The infrared optical pyrometer is a widely used existing device in the art and is one of the indispensable temperature measuring instruments in the production processes of metallurgy, chemical industry, and machinery. The present application uniformly arranges a plurality of infrared optical pyrometers as shown in Figure 3 to form a grid of intersecting optical paths, so that the temperature at each grid intersection of the two-dimensional temperature field can be obtained by calculation. Of course, as mentioned earlier, other two-dimensional temperature field measurement schemes in the prior art can also be used in the present application, and the sensors therein can be arranged in a grid as shown in Figure 3 and the temperature at each grid intersection can be obtained by measurement and calculation, so as to obtain the two-dimensional temperature field of the entire horizontal cross section.

[0036] Figure 2 There are a total of 8 burnout air nozzles 61 in the same layer in Figure 1 , and there are a total of 16 burnout air nozzles 61 in the two-layer structure in Figure 3 , and the measurement paths of the 8 two-dimensional temperature field measuring devices 71 in Figure 3 intersect each other to form a total of 16 grid intersections. Figure 3The grid intersection in the upper right corner corresponds to the burnout air nozzle 61 in the upper right corner of the adjacent layer, and the grid intersection in the horizontal position on the left adjacent to the upper right corner corresponds to the burnout air nozzle 61 in the upper right corner of a more distant layer; the remaining grid intersections can correspond to the remaining burnout air nozzles 61 according to the same principle. Of course, it is also possible to correspond to one or more burnout air nozzles 61 based on the fitting of multiple grid intersections, and adjust the airflow and swing angle of one or more burnout air nozzles 61 accordingly based on the temperature distribution of multiple grid intersections.

[0037] For example, as mentioned earlier, multiple two-dimensional temperature field measuring devices 71 are uniformly arranged in a grid on the horizontal cross-section of the flue. The measured temperature field can reflect an indicator of whether the combustion in the entire furnace is uniform and sufficient. In particular, if, based on the temperature distribution of each grid point in the measured temperature field, it is calculated that the temperature center of the temperature field is not located at the geometric center of the flue, for example, compared to... Figure 2 and Figure 3 The layout shown, if the temperature center deviates to Figure 3 The corresponding grid intersection point is located in the upper right corner. Figure 2 The airflow in the upper right corner area of ​​the burnout air nozzle 61 may be weak, or the swing angle of the burnout air nozzle 61 may be off. In this case, the damper opening and swing angle of the corresponding upper right corner burnout air nozzle 61 can be adjusted to increase the burnout airflow in this area and make the swing angle of the burnout air nozzle 61 "push" the temperature center towards the geometric center, so that the flame center is centered. Alternatively, as mentioned above, the swing angle and airflow of the burnout air nozzle 61 on the opposite side can be used to "pull" the temperature center towards the geometric center; or both directions can be adjusted simultaneously, combining "push" and "pull" adjustments.

[0038] Of course, the layout of the burnout air nozzles 61 shown in the diagram is merely an illustrative example. In actual applications, more burnout air nozzles 61 can be provided as needed, and they are not limited to being arranged only on the front and rear walls, but can also be evenly distributed around the entire burnout zone. Similarly, more two-dimensional temperature field measuring devices 71 can be arranged in the horizontal section above the burnout zone 200 to form a finer grid layout, which can obtain more accurate temperature values ​​at each grid intersection of the two-dimensional temperature field.

[0039] Furthermore, such as Figure 1As shown, corresponding to the main combustion zone 100, each of the pulverized coal pipes 30 is provided with a pulverized coal flow measuring sensor 34, a primary air flow sensor 32 and a primary air-pulverized coal adjusting valve 33; each of the secondary air nozzles 31 is provided with a secondary air flow sensor 42 and a secondary air damper 43 in the corresponding secondary air pipe 40; the pulverized coal flow measuring sensor 34, the primary air flow sensor 32, the primary air-pulverized coal adjusting valve 33, the secondary air flow sensor 42 and the secondary air damper 43 are connected to the main combustion zone control module 5 through control cables. Further, in order to control the total amount of secondary air, the secondary air main pipe 44 connecting the secondary air box 4 and each of the secondary air pipes 40 is provided with a total amount of secondary air damper 45, which is connected to the main combustion zone control module 4 through a control cable.

[0040] Among them, the pulverized coal flow measuring sensor 34, the primary air flow sensor 32 and the secondary air flow sensor 42 can adopt any suitable sensor that can directly measure the flow in the prior art, or any suitable device or method that can indirectly measure the flow in the prior art. For example, those skilled in the art can use the device or method in the prior art CN103939939B as an entity or virtual sensor in this application to directly or indirectly calculate the pulverized coal flow, primary air and secondary air flow.

[0041] Further, corresponding to the burnout zone 200, each of the burnout air nozzles 61 is connected to the secondary air box 4 through a burnout air pipe 60, and each of the burnout air pipes 60 corresponding to the burnout air nozzles 61 is provided with a burnout air flow sensor 62 and a burnout air damper 63; each of the burnout air nozzles 61 is provided with a swing angle adjusting device 72 and a driving link 73, and the swing angle adjusting device 72 can drive the driving link 72 to move, thereby driving the burnout air nozzles 61 to deflect the swing angle. The swing angle adjusting device 72, the burnout air flow sensor 62, the burnout air damper 63 and the two-dimensional temperature field measuring device 71 are connected to the burnout zone control module 7 through control cables. Among them, the secondary air box 4 is used to provide secondary air and burnout air, thereby simplifying the system structure and saving cost. Similarly, the burnout air flow sensor 62 can adopt any suitable sensor that can directly measure the flow in the prior art, or any suitable device or method that can indirectly measure the flow in the prior art.

[0042] The two-dimensional temperature field combustion control method of the present application will be further described in detail below with reference to the accompanying drawings, which comprises the following steps:

[0043] Step A: In the main combustion zone 100, first adjust the pulverized coal flow in each pulverized coal pipeline 30 corresponding to each burner 31 to be substantially the same; then adjust the opening of the secondary air damper 43 of each burner 31, so that the air-coal ratio of each burner 31 is substantially the same.

[0044] Specifically, the step A further comprises: according to the measured primary air flow and the pulverized coal flow in each pulverized coal pipeline 30, adjusting the pulverized coal flow in each pulverized coal pipeline 30 corresponding to each burner 31 to be substantially the same. More specifically, for example, the pulverized coal flow in each pulverized coal pipeline 30 can be measured by the pulverized coal flow measuring sensor 34, and the primary air flow in each pulverized coal pipeline 30 can be measured by the primary air flow sensor 32. The above flow information is transmitted to the main combustion zone control module 5 through the control cable. The main combustion zone control module 5 controls the opening of the primary air pulverized coal adjusting valve 33 according to the pulverized coal flow and the primary air flow signals in each pulverized coal pipeline 30, so as to adjust the pulverized coal flow in each pulverized coal pipeline 30 corresponding to each burner 31 to be substantially the same. The so-called substantially the same can be set within an error range of a calibration value, for example, ±5%.

[0045] Further specifically, under the premise of keeping the pulverized coal flow in each pulverized coal pipeline 30 corresponding to each burner 31 substantially the same, according to the measured secondary air flow of each secondary air nozzle 41, adjust the opening of the secondary air damper 43 of each secondary air nozzle 41 of each burner 31, so that the air-coal ratio of each burner 31 is substantially the same. More specifically, for example, the secondary air flow of each secondary air nozzle 41 can be measured by the secondary air flow sensor 42, and the flow signal is transmitted to the main combustion zone control module 5 through the control cable. The main combustion zone control module 5 calculates the total air flow by the previously obtained primary air flow and secondary air flow, and then controls the opening of the secondary air damper 43, so as to adjust the total air flow corresponding to each burner 31 to be substantially the same. Since the pulverized coal flow has been adjusted to be substantially the same before, only the pulverized coal flow in each pulverized coal pipeline 30 needs to be kept unchanged, and only the opening of the secondary air damper 43 needs to be changed, which greatly simplifies the control program.

[0046] Step B: Keep the operating parameters in the main combustion zone 100 unchanged, and adjust the flow and swing angle of the burnout air nozzle 61 corresponding to the position of the two-dimensional temperature field in the burnout zone 200 according to the temperature distribution of the two-dimensional temperature field obtained by the two-dimensional temperature field measuring device 71 in real time, so that the flame center in the furnace of the coal-fired boiler 1 is kept at the geometric center position of the flue.

[0047] Specifically, for example, under the premise of keeping the operating parameters in the main combustion zone 100 unchanged, the two-dimensional temperature field signal measured by the two-dimensional temperature field measuring device 71 and the overfire air flow signal measured by the overfire air flow sensor 62 are transmitted to the overfire zone control module 7 through the control cable, and the overfire zone control module 7 controls the overfire air nozzle 61 corresponding to the deviation position of the temperature center of the two-dimensional temperature field measured by the two-dimensional temperature field measuring device 71 from the geometric center of the flue, controls the opening size and swing angle of the overfire air damper 63 of the corresponding overfire air nozzle 61, and increases or decreases the overfire air flow in a targeted manner, and changes the swing angle, so that the air volume of the region is increased or decreased, so that the position of the flame center is adjusted to coincide with the geometric center of the flue.

[0048] Further, Figure 2 and Figure 3 The one-to-one correspondence between the corresponding overfire air nozzle 61 and the grid layout of the two-dimensional temperature field measuring device 71 can be determined by measuring the exhaust emission pollutant concentration, coal loss, and heating surface coking and slagging parameters to determine the technical effect of the two-dimensional temperature field combustion control method of the present application.

[0049] For example, by using the control system and control method of the present application, compared with the conventional total amount type and fuzzy type combustion control method, under the same combustion load and coal mass conditions, the control system and method of the present application reduces the coal loss by 7.6%-8.5%, the CO / NOx content of the exhaust gas is reduced by 15-21%, and the average cleaning interval of the heating surface coking and slagging is extended by 60-90 days, greatly improving the coal combustion efficiency and emission level, saving downtime, and saving costs.

[0050] In addition, the control method of the present application adopts segmented independent control. In the main combustion zone, the coal flow is first adjusted, and the secondary air flow is independently adjusted under the condition that the coal flow is determined. Under the condition that the main combustion zone parameters are determined, the temperature data of different positions in the entire flue cross section are obtained by the two-dimensional temperature field measuring device arranged in a grid layout at the outlet, and the overfire air flow and swing angle of the corresponding region are adjusted, thereby realizing independent simplified control relative to the main combustion zone. Since the two-dimensional temperature field measuring device obtains data of the entire region, the overfire air flow and swing angle of the corresponding region can be adjusted according to different regions, and accurate control is realized. Thus, the method of the present application not only realizes independent simplified control, but also realizes accurate control, and the system structure and implementation scheme are simple and effective, greatly simplifying the equipment and reducing the cost.

[0051] Those skilled in the art should understand that, although the present application is described in the manner of multiple embodiments, not every embodiment contains only one independent technical solution. The description is made in this way only for the sake of clarity, those skilled in the art should understand the specification as a whole and understand the technical solutions involved in each embodiment as being combined into different embodiments to understand the protection scope of the present application.

[0052] The above merely describes the specific implementation of the present application in a schematic manner, and is not intended to limit the scope of the present application. Any equivalent changes, modifications and combinations made by any person skilled in the art without departing from the concept and principle of the present application shall fall within the scope of protection of the present application.

Claims

1. A two-dimensional temperature field combustion control method for controlling combustion of a coal-fired boiler (1) by a two-dimensional temperature field, wherein, The main combustion zone (100) of the coal-fired boiler (1) is provided with a plurality of burners (31) and a secondary air nozzle (41) corresponding to each burner (31); the burnout zone (200) of the coal-fired boiler (1) is provided with a plurality of burnout air nozzles (61); the horizontal cross section of the flue above the burnout zone (200) is provided with a two-dimensional temperature field measuring device (71) arranged in a grid. Step A: In the main combustion zone (100), first adjust the coal flow in each coal powder pipeline (30) corresponding to each burner (31) to be substantially the same; then adjust the opening of the secondary air damper (43) of each burner (31) so that the air-coal ratio of each burner (31) is substantially the same; Step B: Keep the operating parameters in the main combustion zone (100) unchanged, adjust the flow and swing angle of the burnout air nozzles (61) in the burnout zone (200) corresponding to the two-dimensional temperature field according to the temperature distribution of the two-dimensional temperature field obtained by real-time detection of the two-dimensional temperature field measuring device (71), so that the flame center in the furnace of the coal-fired boiler (1) is kept at the geometric center position of the flue.

2. The method of claim 1, wherein, The step A further comprises: adjusting the coal flow in each coal powder pipeline (30) corresponding to each burner (31) to be substantially the same according to the measured primary air flow and coal flow in each coal powder pipeline (30).

3. The method of claim 2, wherein, The step A further comprises: under the premise of keeping the coal flow in each coal powder pipeline (30) corresponding to each burner (31) substantially the same, adjusting the opening of the secondary air damper (43) of the secondary air nozzle (41) of each burner (31) according to the measured secondary air flow of each secondary air nozzle (41), so that the air-coal ratio of each burner (31) is substantially the same.

4. The method of claim 1, wherein, A plurality of two-dimensional temperature field measuring devices (71) are uniformly arranged around the flue above the burnout zone (200), and the measurement paths of the plurality of two-dimensional temperature field measuring devices (71) intersect with each other to form a plurality of grid intersection points, and the temperature at each grid intersection point position constitutes the two-dimensional temperature field.

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