Boiler combustion multi-element collaborative optimization control system based on accurate measurement

Abstract

The utility model relates to the technical field of boiler combustion control, and particularly discloses a boiler combustion multi-element collaborative optimization control system based on accurate measurement, which comprises a basic coal-fired power generation system consisting of a boiler, a large wind box, a medium-speed coal mill, a denitration device and an air preheater, and a plurality of measuring devices for acquiring boiler measurement data, the DCS is in signal connection with all the measuring devices and is used for controlling the operation of the whole system; the combustion optimization control system is connected with the output end of the DCS and is used for receiving real-time boiler measurement data; the output end of the combustion optimization control system is connected with the DCS to form a closed-loop optimization control structure; compared with the prior art, the system can adapt to changes of boiler loads, coal quality and operation modes, dynamic real-time optimization is carried out, boiler efficiency is improved, nitric oxide is reduced, and meanwhile smoke temperature deviation is reduced in a coordinated mode.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of boiler combustion control technology, concretely relates to the boiler combustion multivariate collaborative optimization control system based on accurate measurement. BACKGROUND

[0002] Coal powder furnace is the main furnace type of power plant boiler in China. In modern coal powder boiler, the combustion of coal powder mainly relies on the combustion system. Broadly speaking, the combustion system of the boiler includes the coal pulverizing system, the furnace, the burner and its auxiliary equipment. The problems to be solved include: (1) stable combustion; (2) reasonable distribution of heat; (3) high combustion efficiency; (4) low nitrogen oxide generation; (5) prevention of high-temperature corrosion of water-cooled wall; (6) prevention of boiler coking; (7) prevention of over-temperature of boiler heating surface tube.

[0003] The coal powder boiler relies on the entrainment of jet to organize the combustion in the furnace, and the reasonable air distribution is the key to ensure the combustion performance of the boiler. In modern coal powder boiler, the total air entering the furnace includes: the primary air for drying and conveying coal powder, the secondary air entering the furnace through the large air box and the unorganized air leakage. For the control of the primary air under various loads, the air-coal ratio curve of the coal mill operation is generally referred to for adjustment. Due to the uneven mixing of the cold and hot air at the inlet of the coal mill and the inlet flow field of the coal mill, the inlet air flow of the coal mill is often inaccurate, resulting in generally low control accuracy of the primary air. For the control of the secondary air under various loads, the air flow is generally not measured separately, but is adjusted only by controlling the oxygen content at the outlet of the furnace. Under different loads, the air flow of each layer of the secondary air chamber is adjusted by controlling the differential pressure of the large air box / furnace and adjusting the opening degree of each layer of the air door. Since the air distribution mode of the large air box is generally adopted in the existing service boilers, the structure of the air box is compact, and there is not enough premixing section to accurately measure the air flow entering each layer of the air chamber, so quantitative adjustment cannot be realized. Some power plants abroad adopt the design of independent secondary air duct, which can realize quantitative control of the secondary air, but the problem is that the pipeline arrangement is complicated and not suitable for large-scale promotion. For the unorganized air leakage, the air leakage is generally not measured separately, and this part of the air has the characteristic that the air leakage basically does not change with the load, which can be roughly measured by test.

[0004] Under the condition that the main and auxiliary equipment are not subjected to large-scale modification, it is recognized that the development of combustion optimization adjustment is the most effective technical means to improve the economic and clean performance of the boiler. At present, the development of combustion optimization adjustment at home and abroad mainly includes the following directions: (1) combustion optimization based on adjustment test, which often needs to carry out a large number of orthogonal and single-factor rotation tests on the field boiler, and a large amount of effort is required, and the conditions are limited. (2) combustion optimization based on advanced detection technology, which has high cost and the accuracy of the measurement results is difficult to effectively verify. (3) combustion optimization based on machine learning algorithm, which has low cost and good promotion, but requires high accuracy of the monitored data of the boiler operation.

[0005] Therefore, the skilled in the art urgently need to provide a new idea to solve the problem of the existing boiler combustion optimization adjustment only by qualitative adjustment experience. Utility model content

[0006] Therefore, the utility model wants to solve the technical problem in the prior art is to overcome the defects, thereby providing a kind of boiler combustion multivariate collaborative optimization control system based on accurate measurement.

[0007] A kind of boiler combustion multivariate collaborative optimization control system based on accurate measurement, including: by boiler, large wind box, medium speed coal mill, denitration device, air preheater constitutes the basic coal-fired power generation system, it is characterized by further comprising:

[0008] A plurality of measuring devices for obtaining boiler measurement data are obtained;

[0009] DCS distributed control system is connected with all measuring devices signals, and is used for the overall system operation control;

[0010] And the combustion optimization control system for receiving real-time boiler measurement data is connected with the output end of DCS distributed control system;The output end of combustion optimization control system is connected with DCS distributed control system, and constitutes closed-loop optimization control structure;

[0011] Wherein, the combustion optimization control system includes: communication acquisition system, machine learning system and optimization system;

[0012] The receiving end of the communication acquisition system is connected with DCS distributed control system 17 signal, receives real-time boiler operation data;

[0013] The receiving end of the machine learning system is connected with the output end of communication acquisition system signal, receives the combustion boundary quantity data in real-time boiler operation data;

[0014] The receiving end of the optimization system is connected with the output end of machine learning system signal, for receiving the combustion effect quantity data output by the output end of machine learning system, and outputting intelligent optimization control instruction.

[0015] Preferably, the measuring device includes:

[0016] Furnace water-cooled wall temperature measuring device arranged in the interior of boiler;

[0017] Secondary air accurate measurement device is arranged at the extension end of each damper adjusting baffle drive shaft of large wind box;

[0018] Coal mill inlet air volume accurate measurement device is arranged at the inlet of medium speed coal mill;

[0019] Furnace outlet temperature measuring device is arranged at the upper layer of boiler overfire air;

[0020] A boiler main steam temperature measuring device and a boiler reheat steam temperature measuring device are respectively arranged on the outlet steam pipes of the boiler main steam pipe and the reheat steam pipe;

[0021] A denitration inlet oxygen quantity precise measuring device and a denitration inlet nitrogen oxide precise measuring device are arranged on the denitration device inlet flue;

[0022] An exhaust gas oxygen quantity measuring device, an exhaust gas temperature measuring device and a fly ash carbon content measuring device are arranged on the air preheater outlet flue.

[0023] Preferably, the secondary air precise measuring device comprises a rotary absolute value encoder and a secondary air calculator;

[0024] Based on the principle of soft measurement, a rotary absolute value encoder is added to the extension end of the damper baffle driving shaft to obtain the opening degree of each layer of damper;

[0025] The secondary air calculator is connected with the rotary absolute value encoder to realize the calculation of the air quantity passing through each layer of secondary air nozzle based on the corresponding resistance coefficient of different damper opening degrees.

[0026] Preferably, the coal mill inlet air quantity precise measuring device comprises an air quantity measuring meter and a cold and hot air uniform flow mixer;

[0027] The air quantity measuring meter adopts a multi-point matrix flowmeter and is arranged at the inlet of the medium-speed coal mill;

[0028] The cold and hot air uniform flow mixer is arranged at the cold and hot air mixing position and adopts a stepped grid structure to ensure that the cold air is uniformly mixed without affecting the flow of the hot primary air.

[0029] Preferably, the exhaust gas oxygen quantity measuring device and the exhaust gas temperature measuring device are arranged on the air preheater outlet flue and adopt a grid method layout;

[0030] The exhaust gas temperature measuring device adopts a sheathed armored thermocouple;

[0031] The exhaust gas oxygen quantity measuring device adopts a zirconia analyzer.

[0032] Preferably, the furnace outlet temperature measuring device adopts the sound wave temperature measurement principle and comprises four generators, six receivers and a furnace outlet temperature calculation processor;

[0033] Each generator and the six receivers form a pair of six transceiver connection relationship;

[0034] The furnace outlet temperature calculation processor is connected with the generators and the receivers in signal and is used to receive the time difference and the position between the generators and the receivers.

[0035] Preferably, the denitration inlet oxygen quantity precision measuring device and the denitration inlet nitrogen oxide precision measuring device are arranged in the denitration inlet flue, and are arranged in a grid method so that the flue gas after being filtered is analyzed by spectrum analysis to obtain the flue gas composition.

[0036] The technical scheme of the utility model has the following advantages:

[0037] Compared with the prior art, the utility model can adapt to the changes of boiler load, coal quality and operation mode, perform dynamic real-time optimization, improve the boiler efficiency, reduce the nitrogen oxides, and simultaneously cooperatively reduce the flue gas temperature deviation. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical scheme in the embodiment of the utility model or the prior art, the drawings needed to be used in the embodiment or the prior art description will be briefly introduced as follows, and obviously, the drawings in the following description are some embodiments of the utility model, and for those skilled in the art, other drawings can be obtained without creative labor on the basis of the drawings.

[0039] Figure 1 It is a structural schematic diagram of the boiler combustion multi-element collaborative optimization control system based on precision measurement of the utility model.

[0040] Figure 2 It is a side view of the secondary air door precision measuring device.

[0041] Figure 3 It is a front view of the secondary air door precision measuring device.

[0042] Figure 4 It is a side view of the cold and hot air uniform flow mixing device of the coal mill inlet air duct.

[0043] Figure 5 It is a front view of the cold and hot air uniform flow mixing device of the coal mill inlet air duct.

[0044] Figure 6 It is a top view of the cold and hot air uniform flow mixing device of the coal mill inlet air duct.

[0045] Figure 7 It is a schematic diagram of the machine learning modeling and optimization process of the combustion optimization control system of the utility model.

[0046] BRIEF DESCRIPTION OF DRAWINGS:

[0047] 1-boiler, 2-furnace water wall temperature measuring device, 3-large wind box, 4-accurate measurement device of air door opening, 5-medium speed coal mill, 6-accurate measurement device of mill inlet air volume, 7-furnace outlet temperature measuring device, 8-boiler main steam temperature measuring device, 9-boiler reheat steam temperature measuring device, 10-denitration device, 11-accurate measurement device of denitration inlet oxygen, 12-accurate measurement device of denitration inlet nitrogen oxide, 13-air preheater, 14-flue gas oxygen content measuring device, 15-flue gas temperature measuring device, 16-flying ash carbon content measuring device, 17-DCS distributed control system, 18-burning optimization control system. DETAILED DESCRIPTION

[0048] The technical solutions of the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0049] In the description of the present application, it should be noted that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0050] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the communication inside two elements. For those skilled in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0051] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as there is no conflict.

[0052] Example 1

[0053] The embodiment discloses a boiler combustion multi-element collaborative optimization control system based on accurate measurement, which comprises a basic coal-fired power generation system composed of a boiler 1, a large air box 3, a medium-speed coal mill 5, a denitration device 10 and an air preheater 13, and further comprises:

[0054] A plurality of measuring devices for acquiring boiler measurement data;

[0055] A DCS (Distributed Control System) 17 connected with all the measuring devices and used for overall system operation control;

[0056] A combustion optimization control system 18 connected with an output end of the DCS 17 and used for receiving real-time boiler measurement data; the combustion optimization control system 18 is connected with the DCS 17, and a closed-loop optimization control structure is formed;

[0057] The combustion optimization control system 18 comprises a communication acquisition system, a machine learning system and an optimization system.

[0058] The receiving end of the communication acquisition system is connected with the DCS 17 in signal and used for receiving real-time boiler operation data; the real-time boiler operation data is composed of the boiler measurement data and historical boiler operation data stored in the DCS.

[0059] The receiving end of the machine learning system is connected with the output end of the communication acquisition system in signal and used for receiving combustion boundary data in the real-time boiler operation data.

[0060] The receiving end of the optimization system is connected with the output end of the machine learning system in signal and used for receiving combustion effect data output by the output end of the machine learning system and outputting intelligent optimization control instructions.

[0061] Specifically,

[0062] For example, Figure 1 In the embodiment, the measuring devices comprise:

[0063] A furnace water cooling wall temperature measuring device 2 arranged in the boiler 1; specifically, the boiler 1 is a once-through boiler, and the water cooling wall of the boiler 1 adopts a type of "lower spiral pipe ring + middle full-mixed header + upper vertical pipe screen". The furnace water cooling wall temperature measuring device 2 is arranged on a spiral water cooling wall outlet header inlet pipe, and the temperature distribution of the water cooling wall pipe at each position is measured to reflect the deviation of the heat load in the furnace.

[0064] A secondary air precision measurement device 4 is arranged at the extended end of the damper adjusting baffle drive shaft of each wind box 3; the secondary air precision measurement device adopts the principle of soft measurement, and a rotary absolute value encoder is added at the extended end of the damper baffle drive shaft to accurately record the real position of each layer of damper; in combination with the resistance coefficient corresponding to different damper openings, the real air volume passing through each layer of secondary air nozzle of the boiler can be accurately calculated. Specifically, in this embodiment, the secondary air precision measurement device 4 includes a rotary absolute value encoder and a secondary air calculator;

[0065] Based on the principle of soft measurement, a rotary absolute value encoder is added at the extended end of the damper baffle drive shaft to obtain the opening of each layer of damper;

[0066] The secondary air calculator is connected with the rotary absolute value encoder to calculate the air volume passing through each layer of secondary air nozzle based on the resistance coefficient corresponding to different damper openings.

[0067] Specifically: in actual application, the end of the large wind box 3 is divided into several wind chambers, and the end of each wind chamber is connected with a burner nozzle; the inlet of each wind chamber is arranged with a damper adjusting baffle, and the extended end of the damper adjusting baffle drive shaft is arranged with a damper opening precision measurement device 4, as shown in Figures 2-3 The rotary absolute value encoder 17 accurately records the opening of each layer of damper, and in combination with the resistance coefficient corresponding to different damper openings, the air volume passing through each layer of secondary air nozzle is accurately calculated. The specific process is as follows:

[0068] 1 During shutdown, check the state of each layer and each angle of secondary air damper and actuator in detail to ensure that the damper is in place.

[0069] 2 Under the condition of cold state ventilation test, install a flow rate measurement device on each layer of secondary air nozzle. Start the fan, adjust the large wind box 3 / furnace differential pressure to 0.5-0.6 kPa, and adjust the rotation angle of each layer of secondary air damper baffle to 100%, 75%, 50%, 40%, 30%, 20%, 10% and 0% in turn. Record the large wind box 3 / furnace differential pressure at different openings of each layer of damper, and synchronously record the dynamic pressure value of secondary air at each layer of nozzle. Based on the secondary air calculator, the resistance coefficient corresponding to each layer of damper at different openings is obtained.

[0070] 3 During hot state operation, according to the opening of each layer of damper, the resistance characteristic data of damper and the wind box / furnace differential pressure, and comprehensively considering the self-generated ventilation of furnace, the ventilation volume of each layer of secondary air nozzle can be calculated.

[0071] The inlet of the medium-speed coal mill 5 is arranged with an air volume precision measurement device 6, including a cold and hot air flow mixer and an air volume measurement meter. The cold and hot air flow mixer is arranged at the mixing position of cold and hot air duct, and the structure is as Figures 4-6As shown, the grid structure formed by the staggered hot air longitudinal baffle and the stepped cold air transverse baffle can ensure that the cold air is uniformly mixed into the hot air without affecting the flow of the hot primary air.

[0072] The coal mill inlet air volume accurate measuring device 6 is arranged at the inlet of the medium-speed coal mill 5; specifically, in this embodiment, the coal mill inlet air volume accurate measuring device 6 comprises an air volume measuring meter and a cold and hot air uniform flow mixer.

[0073] The air volume measuring meter is a multi-point matrix flow meter, which is arranged at the inlet of the medium-speed coal mill 5, and the straight pipe section before the air volume measuring meter has a length of ≥3 times the water power diameter of the air duct.

[0074] The cold and hot air uniform flow mixer is arranged at the cold and hot air mixing position and adopts a stepped grid structure to ensure that the cold air or the temperature-adjusted air is uniformly mixed without affecting the flow of the hot primary air.

[0075] The furnace outlet temperature measuring device 7 is arranged at the upper layer of the burn-off air of the boiler 1 and adopts a non-contact temperature measuring principle to measure the temperature field distribution on the entire furnace cross section to accurately identify the temperature deviation of the flame in the furnace; specifically, the furnace outlet temperature measuring device 7 adopts an acoustic wave temperature measuring principle and comprises four generators, six receivers and a furnace outlet temperature calculation processor.

[0076] Each generator and the six receivers form a six-transmit-receive connection relationship.

[0077] The furnace outlet temperature calculation processor is signal-connected with the generators and the receivers to receive the time difference and the position between the generators and the receivers.

[0078] The boiler main steam temperature measuring device 8 and the boiler reheat steam temperature measuring device 9 are respectively arranged on the outlet steam guide pipes of the main steam pipeline and the reheat steam pipeline of the boiler 1.

[0079] The denitration inlet oxygen quantity accurate measuring device 11 and the denitration inlet nitrogen oxide accurate measuring device 12 are arranged at the inlet flue of the denitration device 10; specifically, the denitration inlet oxygen quantity accurate measuring device 11 and the denitration inlet nitrogen oxide accurate measuring device 12 are arranged at the inlet flue of the denitration device 10 and adopt a grid layout to obtain the composition of the flue gas through spectral analysis after the flue gas is filtered.

[0080] The flue gas oxygen quantity measuring device 14, the flue gas temperature measuring device 15 and the fly ash carbon content measuring device 16 are arranged at the outlet flue of the air preheater 13; specifically, the flue gas oxygen quantity measuring device 14 and the flue gas temperature measuring device 15 are arranged at the outlet flue of the air preheater 13 and adopt a grid layout.

[0081] The flue gas temperature measuring device 15 adopts a sheathed armored thermocouple.

[0082] The flue gas oxygen content measuring device 14 adopts a zirconium oxide analyzer.

[0083] The fly ash carbon content measuring device is arranged at the air preheater 13 outlet flue, and uses compressed air to form a negative pressure to intermittently extract fly ash in the flue gas into a specific container. A laboratory personnel periodically takes a sample to analyze the composition, and records the data in an offline manner.

[0084] Example 2

[0085] On the basis of Example 1, Example 2 further details the use method of the combustion optimization control system 18.

[0086] In actual application, the combustion optimization control system 18 is arranged in a workstation and connected with the DCS distributed control system 17 to bidirectionally transmit data in a communication manner. The combustion optimization control system 18 includes a communication acquisition system, a machine learning system and an intelligent optimization system.

[0087] The communication acquisition system acquires real-time boiler operation data in a communication manner, and transmits the control instructions generated by the combustion optimization control system 18 back to the DCS distributed control system 17, so as to realize closed-loop optimization control of boiler combustion by means of the configuration logic in the DCS distributed control system 17.

[0088] The functions of the machine learning system include data preprocessing and model training. The machine learning model established in the machine learning system is a recurrent neural network derived model, which adopts a partition classification modeling strategy, and uses real-time boiler operation data as training data, which is further divided into combustion boundary quantity data and combustion effect quantity data. Among them, the combustion boundary quantity includes the coal quantity of each layer of coal mill, the air quantity of each coal mill, the main steam flow and the secondary air damper opening degree; the combustion effect quantity includes the flue gas temperature, the denitration inlet chloric oxide, the boiler reheated steam temperature, the fly ash combustible content, the furnace outlet flue gas temperature deviation and the furnace outlet oxygen content. After the real-time boiler operation data is processed by data cleaning, data specification and normalization, it is used as the basic data for modeling, and a time series model such as RNN, LSTM, GRU encapsulated by PyTorch or Tensorflow framework is used to establish a boiler combustion prediction model, as shown in FIG. 2. Figure 7 Further, in order to improve the accuracy of the model, the boiler combustion prediction model adopts a partition classification modeling strategy.

[0089] The intelligent optimization system adopts a multi-objective optimization genetic algorithm, comprehensively considers each index, completes the optimization of the prediction model, and finally outputs the secondary air damper correction, the coal mill coal quantity correction, the coal mill total air quantity correction and the boiler total oxygen content correction.

[0090] By the above scheme, the boiler combustion multi-element collaborative optimization control system based on accurate measurement can adapt to the changes of power plant boiler load, coal quality and operation mode to realize real-time optimization of boiler dynamics, improve the intelligent level of boiler operation, collaboratively optimize the boiler efficiency and the concentration of nitrogen oxides at the furnace outlet, and ensure the safety of the boiler heating surface.

[0091] Obviously, the above embodiments are only examples for clearly illustrating but not limiting the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the embodiments need not and cannot be exhausted. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A boiler combustion multi-element collaborative optimization control system based on precise measurement, comprising: A basic coal-fired power generation system consisting of a boiler (1), a large air box (3), a medium-speed coal mill (5), a denitrification device (10), and an air preheater (13) is characterized by further comprising: Multiple measuring devices for acquiring boiler measurement data; A DCS distributed control system (17) that connects to all measuring device signals and is used for overall system operation control. And a combustion optimization control system (18) connected to the output of the DCS distributed control system (17) to receive real-time boiler measurement data; the output of the combustion optimization control system (18) is connected to the DCS distributed control system (17) to form a closed-loop optimization control structure; The combustion optimization control system (18) includes: a communication acquisition system, a machine learning system, and an optimization system; The receiving end of the communication acquisition system is connected to the DCS distributed control system (17) to receive real-time boiler operation data; The receiving end of the machine learning system is connected to the output end of the communication acquisition system to receive combustion boundary quantity data from the real-time boiler operation data. The receiving end of the optimization system is connected to the output end of the machine learning system to receive the combustion effect data output by the machine learning system and output intelligent optimization control commands.

2. The boiler combustion multi-element collaborative optimization control system according to claim 1, characterized in that, The measuring device includes: Temperature measuring device (2) for furnace water-cooled wall installed inside boiler (1); A secondary air precision measuring device (4) is arranged at the extended end of the drive shaft of each damper adjustment baffle in the large wind box (3). A precise measuring device (6) for measuring the inlet air volume of a coal mill is installed at the inlet of a medium-speed coal mill (5); A furnace outlet temperature measuring device (7) is installed above the burnout air of the boiler (1); A boiler main steam temperature measuring device (8) and a boiler reheat steam temperature measuring device (9) are respectively installed on the outlet steam pipes of the main steam pipe and the reheat steam pipe of the boiler (1). A precise oxygen measurement device (11) and a precise nitrogen oxide measurement device (12) are installed in the inlet flue of the denitrification unit (10). An exhaust oxygen measurement device (14), an exhaust temperature measurement device (15), and a fly ash carbon content measurement device (16) are installed in the exhaust flue of the air preheater (13).

3. The boiler combustion multi-element collaborative optimization control system according to claim 2, characterized in that, The secondary wind precision measurement device (4) includes a rotary absolute encoder and a secondary wind calculator; Based on the principle of soft measurement, a rotary absolute encoder is added to the extended end of the damper drive shaft to obtain the opening degree of each damper. The secondary air calculator is connected to a rotary absolute encoder to calculate the air volume passing through each layer of secondary air nozzles based on the resistance coefficient corresponding to different damper openings.

4. The boiler combustion multi-element collaborative optimization control system according to claim 2, characterized in that, The precise measuring device (6) for the inlet air volume of the coal mill includes: an air volume measuring instrument and a hot and cold air equalization mixer; The air volume measuring instrument is a multi-point matrix flow meter, which is arranged at the inlet of the medium-speed coal mill (5); The hot and cold air equalization mixer is located at the mixing position of the hot and cold air and adopts a stepped grille structure to ensure that the cold air is mixed in evenly without affecting the flow of the hot primary air.

5. The boiler combustion multi-element collaborative optimization control system according to claim 2, characterized in that, The exhaust oxygen measurement device (14) and exhaust temperature measurement device (15) are arranged in the outlet flue of the air preheater (13) using a grid layout. The flue gas temperature measuring device (15) uses a sheathed thermocouple with a sleeve; The exhaust oxygen measurement device (14) uses a zirconium oxide analyzer.

6. The boiler combustion multi-element collaborative optimization control system according to claim 2, characterized in that, The furnace outlet temperature measuring device (7) adopts the principle of acoustic temperature measurement and includes four generators, six receivers and a furnace outlet temperature calculation processor; Each generator is paired with six receivers to form a one-to-six transceiver connection; The furnace outlet temperature calculation processor is connected to the generator and receiver signals to receive the time difference and position between the generator and receiver.

7. The boiler combustion multi-element collaborative optimization control system according to claim 2, characterized in that, The precise oxygen measurement device (11) and the precise nitrogen oxide measurement device (12) at the denitrification inlet are arranged in a grid layout in the denitrification inlet flue so that the flue gas composition can be obtained by spectral analysis after the flue gas is filtered.

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