A method, system and related devices for secondary air distribution in a pulverized coal boiler

Abstract

This application provides a secondary air distribution method for a pulverized coal boiler, comprising: obtaining the number of currently operating pulverizing systems; determining the secondary air distribution method and the distribution coefficient for each layer based on the number of currently operating pulverizing systems; determining the wind speed command for each layer based on the sum of the wind velocities of each layer of the pulverized coal boiler and the distribution coefficient of each layer, and distributing air according to the wind speed command. This application, by obtaining the number of pulverizing systems and determining the secondary air distribution method, can automatically distribute secondary air when the number of operating pulverizing systems differs, without manual intervention, thereby ensuring optimal air-fuel ratio and combustion efficiency and reducing costs. This application also provides a secondary air distribution system for a pulverized coal boiler, a computer-readable storage medium, and an electronic device, which have the aforementioned beneficial effects.

Description

Technical Field

[0001] This application relates to the field of industrial control, and in particular to a secondary air distribution method, system and related apparatus for a pulverized coal boiler. Background Technology

[0002] When the number of pulverized coal boilers in operation is different (0, 1, 2 sets), the corresponding secondary air distribution pattern is different, which affects the air-fuel ratio and cannot guarantee complete combustion.

[0003] Under normal circumstances, depending on the changes in the coal powder silo level, when the operator starts and stops the pulverizing system, the system will operate in one of the following modes for a period of time (ranging from 1 to 8 hours): 0 pulverizing systems operating, 1 pulverizing system operating, or 2 pulverizing systems operating. Due to the different number of pulverizing systems operating, the tertiary air supply volume of the pulverizing system will affect the air distribution structure of the entire furnace. Manual operation may result in problems such as untimely adjustments, leading to uncoordinated operating conditions and air distribution, poor air-fuel ratio, and significantly affected combustion efficiency. Summary of the Invention

[0004] The purpose of this application is to provide a secondary air distribution method, a secondary air distribution system, a computer-readable storage medium, and an electronic device for a pulverized coal boiler, which can achieve optimal secondary air distribution and improve combustion efficiency based on the number of currently operating pulverizing systems and coal type information.

[0005] To solve the above-mentioned technical problems, this application provides a secondary air distribution method for a pulverized coal boiler, the specific technical solution of which is as follows:

[0006] Get the number of currently running milling systems;

[0007] The secondary air distribution method and the air distribution coefficient for each floor are determined based on the number of currently operating pulverizing systems.

[0008] The wind speed command for each layer is determined based on the sum of the wind speeds of each layer of the pulverized coal boiler and the air distribution coefficient of each layer, and the air is distributed according to the wind speed command.

[0009] Optionally, obtaining the number of currently operating milling systems includes:

[0010] Acquire the operating status signal of the coal mill;

[0011] If the number of valid signals in the operating status signal is 0, it is determined that there is 0 sets of powder making equipment;

[0012] If the number of valid signals in the operating status signal is 1, it is determined to be a pulverizing unit;

[0013] If the number of valid signals in the operating status signal is 2, it is determined that there are 2 sets of powder making equipment.

[0014] Optionally, determining the secondary air distribution method based on the number of currently operating pulverizing systems includes:

[0015] If the pulverized coal boiler has zero pulverizing units, a concave air distribution type is determined to be used.

[0016] If the pulverized coal boiler is a single pulverizing unit, an inverted triangle air distribution system shall be adopted.

[0017] If the pulverized coal boiler has two sets of pulverizing equipment, then a positive triangle air distribution system should be adopted.

[0018] Optionally, after determining the secondary air distribution method based on the number of currently operating pulverizing systems, the method further includes:

[0019] The average wind speed of the current layer is determined based on the measured velocity components at the four corners of each layer.

[0020] The wind speed command for each layer is determined by the product of the sum of the average wind speeds of each layer and the wind distribution coefficient.

[0021] Optionally, if the pulverized coal boiler includes a manual dispensing mode and an automatic dispensing mode, it further includes:

[0022] Obtain the manually set air distribution coefficient corresponding to the manual allocation mode.

[0023] Optionally, after determining the secondary air distribution method based on the number of currently operating pulverizing systems, the following may also be included:

[0024] Determine the baseline value for the lower calorific value of coal;

[0025] The manually set air distribution coefficient is corrected based on the actual net calorific value of the current coal type and the reference value of the net calorific value of the coal.

[0026] Optionally, after determining the wind speed command for each layer based on the sum of the wind velocities of each layer of the pulverized coal boiler and the air distribution coefficient of each layer, and distributing the air according to the wind speed command, the method further includes:

[0027] Based on the wind speed command corresponding to each layer of the pulverized coal furnace and the average wind speed of that layer, the opening size of the small damper of that layer is adjusted after PID deviation calculation so that the actual measured average wind speed is consistent with the wind speed command of that layer.

[0028] This application also provides a secondary air distribution system for a pulverized coal boiler, comprising:

[0029] The data acquisition module is used to obtain the number of currently running milling systems;

[0030] The air distribution determination module is used to determine the secondary air distribution method and the air distribution coefficient of each floor based on the number of currently operating pulverizing systems.

[0031] The air distribution module is used to determine the air speed command for each layer based on the sum of the air speeds of each layer of the pulverized coal boiler and the air distribution coefficient of each layer, and to distribute air according to the air speed command.

[0032] This application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method described above.

[0033] This application also provides an electronic device, including a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the method described above when it invokes the computer program in the memory.

[0034] This application provides a secondary air distribution method for a pulverized coal boiler, comprising: obtaining the number of pulverizing systems currently in operation; determining the secondary air distribution method and the distribution coefficient of each layer based on the number of pulverizing systems currently in operation; determining the wind speed command for each layer based on the sum of the wind speeds of each layer of the pulverized coal boiler and the distribution coefficient of each layer, and distributing air according to the wind speed command.

[0035] This application determines the secondary air distribution method by obtaining the number of pulverizing systems. When the number of pulverizing systems in operation is different, the secondary air can be automatically distributed without manual intervention, so as to ensure the optimal air-fuel ratio and combustion efficiency and reduce costs.

[0036] This application also provides a secondary air distribution system for a pulverized coal boiler, a computer-readable storage medium, and an electronic device, which have the aforementioned beneficial effects, and will not be elaborated here. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0038] Figure 1 A flowchart illustrating a secondary air distribution method for a pulverized coal boiler provided in this application embodiment;

[0039] Figure 2 This is a schematic diagram of the secondary air distribution system of a pulverized coal boiler provided in an embodiment of this application. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0041] After the pulverized coal gas stream ignites, the way secondary air is introduced plays a crucial role in ignition stability and the burnout process. For large-capacity boilers, it is important to pay attention to the ability of secondary air to penetrate the flame. Secondary air is introduced after the pulverized coal gas stream ignites. Due to the high viscosity of the high-temperature flame, secondary air must penetrate the flame at a very high velocity to enhance the contact and mixing between the air and the surface of the coke particles. Therefore, the secondary air velocity is usually more than twice that of the primary air velocity.

[0042] In medium-storage pulverized coal boilers, secondary air is typically arranged in 3-5 layers, with each layer having four corners arranged symmetrically in a tangential pattern. The number of secondary air layers is related to the number of feeder layers. With two feeder layers, three or four secondary air layers are arranged; with three feeder layers, four or five secondary air layers are arranged. Taking a three-feeder system with four secondary air layers as an example, when the number of operating units in the pulverizing system varies, operators typically adjust the secondary air ratio in a coarse manner. They either leave it unchanged to maintain a certain margin or adjust it synchronously based on changes in oxygen content and wind speed. This approach fails to guarantee the optimal air-fuel ratio and economy. Furthermore, due to manual operation, there is significant variation in operator skill, resulting in low automation and making precise fine-tuning of the secondary air difficult.

[0043] To solve the above problems, see [link to relevant documentation]. Figure 1 , Figure 1 A flowchart illustrating a secondary air distribution method for a pulverized coal boiler provided in this application embodiment, the method comprising:

[0044] S101: Get the number of currently running pulverizing systems;

[0045] S102: Determine the secondary air distribution method and the air distribution coefficient for each floor based on the number of currently operating pulverizing systems;

[0046] S103: Determine the wind speed command for each layer based on the sum of the wind speeds of each layer of the pulverized coal boiler and the air distribution coefficient of each layer, and distribute the air according to the wind speed command.

[0047] This embodiment applies to the automatic distribution mode of secondary air. In manual distribution mode, the manually set secondary air distribution method can be directly obtained. In automatic distribution mode, the proportion of each layer in the pulverized coal boiler is automatically identified and distributed according to the different coal qualities and the different number of pulverizing systems in operation, and the coefficients are automatically identified and corrected. On the one hand, the secondary air distribution method can be determined according to the number of currently operating pulverizing systems. Specifically, the operating status signal of the coal mill can be obtained first, and then the current number of pulverizing systems can be determined according to the number of valid operating status signals, for example:

[0048] If the number of valid signals in the operating status signal is 0, it is determined that there is 0 sets of powder making equipment;

[0049] If the number of valid signals in the operating status signal is 1, it is determined to be a pulverizing unit;

[0050] If the number of valid signals in the operating status signal is 2, it is determined that there are 2 sets of powder making equipment.

[0051] Depending on the number of pulverizing boilers in operation, different air distribution methods can be adopted, which can be specifically set by those skilled in the art. For example, if there are 0 pulverizing boilers, a concave air distribution method can be used; if there is 1 pulverizing boiler, an inverted triangular air distribution method can be used; and if there are 2 pulverizing boilers, an upright triangular air distribution method can be used.

[0052] In addition, the air distribution coefficient of each floor can be determined, and the sum of the air distribution coefficients of each floor is 1. The secondary air of each floor is calculated according to the distribution ratio coefficient to determine the wind speed command of that floor.

[0053] For wind speed commands, the average wind speed of the current layer can be determined first based on the measured velocity components at the four corners of each layer. Then, the wind speed command for each layer is determined by multiplying the sum of the average wind speeds of all layers by the wind distribution coefficient. After determining the wind speed command, wind distribution can be performed according to the wind speed command. It is easy to understand that the wind speed commands for different layers can differ.

[0054] This application determines the secondary air distribution method by obtaining the number of pulverizing systems. When the number of pulverizing systems in operation is different, the secondary air can be automatically distributed without manual intervention, so as to ensure the optimal air-fuel ratio and combustion efficiency and reduce costs.

[0055] In other embodiments, the pulverized coal boiler may include a manual distribution mode and an automatic distribution mode. In the manual distribution mode, the proportioning coefficients of each layer are always adjusted according to pre-set coefficients, independent of coal quality and the pulverizing system; that is, they are fixed coefficients. Subsequently, it can also enter the automatic distribution mode to adjust the air distribution coefficients from the manual distribution mode accordingly. The specific process can be as follows:

[0056] The first step is to obtain the manually set air distribution coefficient corresponding to the manual allocation mode.

[0057] Step 2: Determine the reference value of the low calorific value of coal quality;

[0058] Step 3: Modify the manually set air distribution coefficient according to the actual low calorific value of the current coal type and the reference value of the low calorific value of coal quality.

[0059] The heat released by a unit mass of fuel during complete combustion is called the calorific value of the fuel. The high calorific value refers to the total heat released when 1 Kg of fuel is completely burned, including the latent heat of vaporization released when the water vapor in the flue gas has condensed into water. When the latent heat of vaporization of the water vapor in the flue gas is deducted from the high calorific value of the fuel, it is called the low calorific value of the fuel.

[0060] Therefore, it is easy to understand that during manual distribution, it is usually set according to the reference value of the low calorific value of coal quality. If there is a difference between the actual low calorific value of the current coal type and the reference value of the low calorific value of coal quality, the air distribution coefficient can be appropriately adjusted.

[0061] Taking a pulverized coal furnace with ABCD four-layer system as an example, setting the reference value of the low calorific value of coal quality as XS and the actual low calorific value of coal quality as XI, a feasible modification process can be as follows:

[0062] When 105% < XI / XS < 110%, the D-layer and C-layer systems are automatically reduced by 0.5% on the basis of the manual setting, and at the same time, the B-layer and A-layer systems are automatically increased by 0.5% on the basis of the manual setting.

[0063] When 110% ≤ XI / XS, the D-layer and C-layer systems are automatically reduced by 1% on the basis of the manual setting, and at the same time, the B-layer and A-layer systems are automatically increased by 1% on the basis of the manual setting.

[0064] When 90% < XI / XS < 95%, the D-layer and C-layer systems are automatically increased by 0.5% on the basis of the manual setting, and at the same time, the B-layer and A-layer systems are automatically reduced by 0.5% on the basis of the manual setting.

[0065] When XI / XS ≤ 90%, the D-layer and C-layer systems are automatically increased by 1% on the basis of the manual setting, and at the same time, the B-layer and A-layer systems are automatically reduced by 1% on the basis of the manual setting.

[0066] When 95% < XI / XS < 105%, the coefficient remains unchanged.

[0067] In other embodiments, if there is a difference between the current number of operating coal pulverizing sets and the corresponding air distribution method and the manually set air distribution method, a further prompt can also be made to determine whether to change the manually set air distribution method.

[0068] As can be seen, this embodiment sets two modes for the secondary air ratio: a manual setting mode and an automatic allocation mode, allowing users to flexibly choose according to the actual process conditions. In the automatic allocation mode, the ratio of secondary air in each layer will be automatically identified and allocated when the number of pulverizing systems or the type of coal differs, without manual intervention, ensuring optimal air-fuel ratio and combustion efficiency.

[0069] Based on the above embodiments, as a preferred embodiment, after determining the wind speed command for each layer according to the sum of the wind speeds of each layer of the pulverized coal boiler and the air distribution coefficient of each layer, and distributing air according to the wind speed command, the opening size of the small damper of the layer can be adjusted according to the wind speed command corresponding to each layer of the pulverized coal boiler and the average wind speed of the layer, through PID deviation calculation, so that the actual measured average wind speed is consistent with the wind speed command of the layer.

[0070] In the pulverized coal boiler, each of the four small dampers on each floor can be designed with a closed-loop PID control system for wind speed. Based on the wind speed command and the deviation calculation of the average wind speed of the floor, the opening of the four small dampers at the corners of the floor is automatically adjusted so that the actual measured average wind speed is consistent with the target wind speed command of the floor.

[0071] The following describes a secondary air distribution system for a pulverized coal boiler provided in the embodiments of this application. The secondary air distribution system described below can be referred to in correspondence with the secondary air distribution method for the pulverized coal boiler described above.

[0072] See Figure 2 , Figure 2 This application provides a schematic diagram of a secondary air distribution system for a pulverized coal boiler, as shown in the embodiments of the present application. The present application also provides a secondary air distribution system for a pulverized coal boiler, comprising:

[0073] The data acquisition module is used to obtain the number of currently running milling systems;

[0074] The air distribution determination module is used to determine the secondary air distribution method and the air distribution coefficient of each floor based on the number of currently operating pulverizing systems.

[0075] The air distribution module is used to determine the air speed command for each layer based on the sum of the air speeds of each layer of the pulverized coal boiler and the air distribution coefficient of each layer, and to distribute air according to the air speed command.

[0076] Based on the above embodiments, as a preferred embodiment, the data acquisition module includes:

[0077] The signal acquisition module acquires the operating status signal of the coal mill; if the number of valid signals of the operating status signal is 0, it is determined to be 0 sets of pulverizing; if the number of valid signals of the operating status signal is 1, it is determined to be 1 set of pulverizing; if the number of valid signals of the operating status signal is 2, it is determined to be 2 sets of pulverizing.

[0078] Based on the above embodiments, as a preferred embodiment, the air distribution determination module is a module for performing the following steps:

[0079] If the pulverized coal boiler has zero pulverizing units, a concave air distribution type is determined to be used.

[0080] If the pulverized coal boiler is a single pulverizing unit, an inverted triangle air distribution system shall be adopted.

[0081] If the pulverized coal boiler has two sets of pulverizing equipment, then a positive triangle air distribution system should be adopted.

[0082] Based on the above embodiments, as a preferred embodiment, it further includes:

[0083] The wind speed command determination module is used to determine the average wind speed of the current layer based on the measured velocity components at the four corners of each layer; and to determine the wind speed command for each layer based on the product of the sum of the average wind speeds of each layer and the wind distribution coefficient.

[0084] Based on the above embodiments, as a preferred embodiment, it further includes:

[0085] The manual coefficient acquisition module is used to acquire the manually set air distribution coefficient corresponding to the manual allocation mode.

[0086] Based on the above embodiments, as a preferred embodiment, it further includes:

[0087] The coefficient correction module is used to determine the baseline value of the lower heating value of coal.

[0088] The manually set air distribution coefficient is corrected based on the actual net calorific value of the current coal type and the reference value of the net calorific value of the coal.

[0089] Based on the above embodiments, as a preferred embodiment, it further includes:

[0090] The damper adjustment module is used to adjust the opening of the small damper of each layer of the pulverized coal boiler according to the wind speed command corresponding to each layer and the average wind speed of the layer, through PID deviation calculation, so that the actual measured average wind speed is consistent with the wind speed command of the layer.

[0091] This application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed, can perform the steps provided in the above embodiments. The storage medium may include various media capable of storing program code, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0092] This application also provides an electronic device that may include a memory and a processor. The memory stores a computer program, and when the processor calls the computer program in the memory, it can implement the steps provided in the above embodiments. Of course, the electronic device may also include various network interfaces, power supplies, and other components.

[0093] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. As the system provided in the embodiments corresponds to the method provided in the embodiments, the description is relatively simple; relevant parts can be found in the method section.

[0094] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this application. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

[0095] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A method for distributing secondary air to a pulverized coal boiler, characterized in that, include: Get the number of currently running milling systems; The secondary air distribution method and the air distribution coefficient for each floor are determined based on the number of currently operating pulverizing systems. The wind speed command for each layer is determined based on the sum of the wind speeds of each layer of the pulverized coal boiler and the air distribution coefficient of each layer, and the air is distributed according to the wind speed command. The step of obtaining the number of currently running milling systems includes: Acquire the operating status signal of the coal mill; If the number of valid signals in the operating status signal is 0, it is determined that there is 0 sets of powder making equipment; If the number of valid signals in the operating status signal is 1, it is determined to be 1 set of powder making; If the number of valid signals in the operating status signal is 2, it is determined that there are 2 sets of powder making equipment; The determination of the secondary air distribution method based on the number of currently operating pulverizing systems includes: If the pulverized coal boiler has zero pulverizing units, a concave air distribution type is determined to be used. If the pulverized coal boiler is a single pulverizing unit, an inverted triangle air distribution system shall be adopted. If the pulverized coal boiler has two sets of pulverizing equipment, then a positive triangle air distribution system should be adopted.

2. The secondary air distribution method according to claim 1, characterized in that, After determining the secondary air distribution method based on the number of currently operating pulverizing systems, the process also includes: The average wind speed of the current layer is determined based on the measured velocity components at the four corners of each layer. The wind speed command for each layer is determined by the product of the sum of the average wind speeds of each layer and the wind distribution coefficient.

3. The secondary air distribution method according to claim 1, characterized in that, If the pulverized coal boiler includes a manual dispensing mode and an automatic dispensing mode, it also includes: Obtain the manually set air distribution coefficient corresponding to the manual allocation mode.

4. The secondary air distribution method according to claim 3, characterized in that, After determining the secondary air distribution method based on the number of currently operating pulverizing systems, the following also includes: Determine the baseline value for the lower heating value of coal; The manually set air distribution coefficient is corrected based on the actual net calorific value of the current coal type and the reference value of the net calorific value of the coal.

5. The secondary air distribution method according to claim 3, characterized in that, The wind speed command for each layer of the pulverized coal boiler is determined based on the sum of the wind velocities of each layer and the air distribution coefficient of each layer. After distributing the air according to the wind speed command, the process further includes: Based on the wind speed command corresponding to each layer of the pulverized coal furnace and the average wind speed of that layer, the opening size of the small damper of that layer is adjusted after PID deviation calculation so that the actual measured average wind speed is consistent with the wind speed command of that layer.

6. A secondary air distribution system for a pulverized coal boiler, characterized in that, include: The data acquisition module is used to obtain the number of currently running milling systems; The air distribution determination module is used to determine the secondary air distribution method and the air distribution coefficient of each floor based on the number of currently operating pulverizing systems. The air distribution module is used to determine the air speed command for each layer based on the sum of the air speeds of each layer of the pulverized coal boiler and the air distribution coefficient of each layer, and to distribute air according to the air speed command. The data acquisition module includes: The signal acquisition module acquires the operating status signal of the coal mill; if the number of valid signals of the operating status signal is 0, it is determined to be 0 sets of pulverizing; if the number of valid signals of the operating status signal is 1, it is determined to be 1 set of pulverizing; if the number of valid signals of the operating status signal is 2, it is determined to be 2 sets of pulverizing. The air distribution determination module is used to perform the following steps: If the pulverized coal boiler has zero pulverizing units, a concave air distribution type is determined to be used. If the pulverized coal boiler is a single pulverizing unit, an inverted triangle air distribution system shall be adopted. If the pulverized coal boiler has two sets of pulverizing equipment, then a positive triangle air distribution system should be adopted.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method as described in any one of claims 1-5.

8. An electronic device, characterized in that, The method includes a memory and a processor, wherein the memory stores a computer program, and the processor, when calling the computer program in the memory, implements the steps of the method as described in any one of claims 1-5.

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