A method and system for measuring primary air flow at coal mill inlet

Abstract

The present invention discloses a method and system for measuring the primary air flow rate at a coal mill inlet. The method comprises the following steps: obtaining the cold primary air temperature before mixing, the hot primary air temperature before mixing, the hot primary air flow rate before mixing, and the primary air temperature at the coal mill inlet after mixing; obtaining the average specific heat capacity before and after hot air mixing and the average specific heat capacity before and after cold air mixing based on the obtained cold primary air temperature before mixing, the hot primary air temperature before mixing, the hot primary air flow rate before mixing, and the primary air temperature at the coal mill inlet after mixing, thereby obtaining the cold primary air flow rate before mixing; and obtaining the primary air flow rate at the coal mill inlet based on the hot primary air flow rate before mixing and the cold primary air flow rate before mixing. This measurement method can accurately obtain the primary air flow rate at the coal mill inlet.

Description

Technical Field

[0001] The invention belongs to the technical field of boilers and relates to a method and system for measuring the primary air flow rate at a coal mill inlet. Background Art

[0002] Direct-blowing pulverizing systems are currently the most widely used in thermal power plants. For these systems, the primary air flow rate at the pulverizer inlet is a key parameter for pulverizing system adjustments and an important basis for boiler automatic control. Accurately measuring the primary air flow rate at the pulverizer inlet facilitates precise control of the pulverizer inlet air-to-coal ratio, stabilizes furnace combustion, adjusts the furnace flame center, and protects the burner nozzle, playing a crucial role in the safe, stable, and economical operation of the boiler.

[0003] Due to the compact layout of thermal power plants, the pulverizer inlet space is relatively small. Cold primary air typically flows into the hot primary air duct from the side or top. The mixed hot primary air is close to the pulverizer inlet, lacking sufficient straight pipe sections for mixing. This results in an uneven primary air flow field within the duct at the pulverizer inlet after mixing. Current methods for measuring the primary air flow at the pulverizer inlet after mixing typically use air volume measurement devices placed directly within the pulverizer inlet duct. Due to the uneven flow field and localized eddies at this location, the measured primary air flow deviates from the actual primary air flow. This deviation also varies irregularly with the opening of the hot and cold dampers, making it impossible to accurately control the primary air flow at the pulverizer inlet. In the existing technology, a disturbance device or a rectifying grid is usually installed in the mixed pipeline to improve the uniformity of the mixed flow field. The air flow rate of the mixed primary air is directly measured by an air volume measuring device installed in the coal mill inlet air duct. However, due to the small space and many elbows at the coal mill inlet, the temperature field in the air duct can be improved by adding a disturbance device or a rectifying grid, but the flow field is still not uniform enough, resulting in the measurement results still failing to meet engineering requirements. Summary of the Invention

[0004] In view of the problems existing in the prior art, the present invention provides a method and system for measuring the primary air flow rate at the inlet of a coal mill, thereby achieving the purpose of accurately measuring the primary air flow rate at the inlet of a coal mill.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for measuring the primary air flow rate at a coal mill inlet comprises:

[0007] Obtain the cold primary air temperature before mixing, the hot primary air temperature before mixing, the hot primary air flow rate before mixing, and the primary air temperature at the coal mill inlet after mixing;

[0008] Obtain the average specific heat capacity before and after hot air mixing and the average specific heat capacity before and after cold air mixing by obtaining the cold primary air temperature before mixing, the hot primary air temperature before mixing, and the coal mill inlet primary air temperature after mixing;

[0009] Obtain the flow rate of the cold primary air before mixing by obtaining the cold primary air temperature before mixing, the hot primary air temperature before mixing, the primary air temperature at the coal mill inlet after mixing, the average specific heat capacity before and after hot air mixing, and the average specific heat capacity before and after cold air mixing;

[0010] The primary air flow rate at the coal mill inlet is obtained by the hot primary air flow rate before mixing and the cold primary air flow rate before mixing.

[0011] Preferably, the process of obtaining the average specific heat capacity before and after the hot air is mixed and the average specific heat capacity before and after the cold air is mixed is specifically as follows:

[0012]

[0013]

[0014] in:

[0015]

[0016]

[0017] Where, The temperature of hot primary air before mixing;

[0018] The temperature of the cold primary air before mixing;

[0019] The temperature of primary air at the inlet of coal mill after mixing;

[0020] is the average temperature before and after the cold wind mixes;

[0021] is the average temperature before and after hot air mixing;

[0022] is the average specific heat capacity before and after hot air mixing;

[0023] is the average specific heat capacity before and after cold air mixing.

[0024] Preferably, the process of obtaining the cold primary air flow rate before mixing is specifically as follows:

[0025]

[0026] Where,

[0027] The cold primary air flow rate before mixing;

[0028] It is the hot primary air flow before mixing.

[0029] Preferably, the process of obtaining the primary air flow rate at the coal mill inlet is specifically as follows:

[0030]

[0031] Where,

[0032] It is the primary air flow rate at the coal mill inlet after mixing.

[0033] Preferably, in the normal operating range of the coal mill, that is, when the cold air temperature at the coal mill inlet is 20-50°C, the hot air temperature is 300-350°C, and the temperature of the primary air after mixing is 200-350°C, the primary air flow rate at the coal mill inlet is:

[0034] .

[0035] A system for measuring the primary air flow rate at a coal mill inlet, comprising:

[0036] Data acquisition module, used to obtain the temperature of cold primary air before mixing, the temperature of hot primary air before mixing, the flow rate of hot primary air before mixing, and the temperature of primary air at the coal mill inlet after mixing;

[0037] a data processing module for obtaining the average specific heat capacity before and after hot air mixing and the average specific heat capacity before and after cold air mixing by obtaining the cold primary air temperature before mixing, the hot primary air temperature before mixing, the hot primary air flow rate before mixing, and the primary air temperature at the coal mill inlet after mixing, thereby obtaining the cold primary air flow rate before mixing; and obtaining the primary air flow rate at the coal mill inlet by obtaining the hot primary air flow rate before mixing and the cold primary air flow rate before mixing;

[0038] The result display module is used to output the acquired primary air flow rate data at the coal mill inlet and display the primary air flow rate at the coal mill inlet.

[0039] Preferably, the data acquisition module includes a hot primary air flow measurement device, a hot primary air temperature measurement device, a cold primary air temperature measurement device and a post-mixing coal mill inlet primary air temperature measurement device;

[0040] The hot primary air flow measuring device and the hot primary air temperature measuring device are arranged in the hot primary air duct;

[0041] The cold primary air temperature measuring device is arranged in the cold primary air duct;

[0042] The device for measuring the temperature of the primary air at the inlet of the mixed coal mill is arranged in the air duct of the primary air at the inlet of the mixed coal mill.

[0043] Preferably, the hot primary air flow measuring device and the hot primary air temperature measuring device are installed at the straight pipe section of the hot primary air duct before mixing; the cold primary air temperature measuring device is installed at the straight pipe section of the cold primary air duct before mixing; and the primary air temperature measuring device at the coal mill inlet after mixing is installed at the straight pipe section of the primary air duct at the coal mill inlet after mixing.

[0044] A terminal device comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the above method when executing the computer program.

[0045] A computer-readable storage medium stores a computer program, wherein the computer program implements the above method when executed by a processor.

[0046] Compared with the prior art, the present invention has the following beneficial technical effects:

[0047] A method for measuring the primary air flow rate at the inlet of a coal mill is disclosed. The primary air flow rate at the inlet of the coal mill is calculated by calculating the hot primary air flow rate before mixing, the hot primary air temperature before mixing, the cold primary air temperature before mixing, and the primary air temperature at the inlet of the coal mill after mixing. In this method, the hot primary air and the cold primary air flow fields before mixing are uniformly distributed, so the hot primary air temperature before mixing, the hot primary air flow rate before mixing, and the cold primary air temperature before mixing can all be accurately measured. Since the primary air after mixing passes through the elbow and the guide plate, the temperature field at the inlet of the coal mill is already very uniform, so the primary air temperature at the inlet of the coal mill can also be accurately measured. Since the specific heat capacity of air has a certain functional relationship with temperature, the average temperature before and after hot air mixing and the average temperature before and after cold air mixing are used as qualitative temperatures, respectively. The corresponding average specific heat capacity can be directly obtained by fitting the function between temperature and specific heat capacity. By calculating the corresponding data, the primary air flow rate at the inlet of the coal mill can be accurately obtained.

[0048] Furthermore, in the normal operating range of the coal mill, that is, the cold air temperature at the coal mill inlet is 20~50℃, the hot air temperature is 300-350℃, and the primary air temperature after mixing is 200-350℃, the calculation method of the primary air flow rate at the coal mill inlet is simplified, which can effectively improve the efficiency of the calculation.

[0049] A system for measuring the primary air flow rate at a coal mill inlet includes a pre-mixing hot primary air flow rate measurement device, a pre-mixing hot primary air temperature measurement device, a pre-mixing cold primary air temperature measurement device, a post-mixing coal mill inlet primary air temperature measurement device, a data acquisition module, and a data processing module. This system effectively and accurately measures the primary air flow rate at the coal mill inlet.

[0050] Furthermore, a flow transmitter is used as a flow measurement device for the hot primary air before mixing, and a temperature transmitter is used as a temperature measurement device for the hot primary air before mixing, a temperature measurement device for the cold primary air before mixing, and a temperature measurement device for the primary air at the coal mill inlet after mixing. This improves measurement accuracy while effectively controlling the cost of the device.

[0051] Furthermore, the hot primary air flow measurement device and the hot primary air temperature measurement device before mixing are installed in the straight pipe section of the hot primary air duct; the cold primary air temperature measurement device before mixing is installed in the straight pipe section of the cold primary air duct; the primary air temperature measurement device at the coal mill inlet after mixing is installed in the straight pipe section of the primary air duct at the coal mill inlet after mixing. The flow field in the straight pipe section is relatively uniform, and the eddy current disturbance is small, which can effectively improve the accuracy of the data. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0053] Figure 1 Schematic diagram of the flow of the method for measuring the primary air flow at the coal mill inlet in the present invention;

[0054] Figure 2 Schematic diagram of the structural connection of the coal mill inlet primary air flow measurement system in an embodiment of the present invention. DETAILED DESCRIPTION

[0055] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0056] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0057] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0058] In the description of the embodiments of the present invention, it should be noted that if the terms "upper," "lower," "horizontal," "inner," etc. appear, the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the inventive product is typically placed when in use. These terms are merely for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first," "second," etc. are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0059] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0060] In the description of the embodiments of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0061] The present invention is described in further detail below with reference to the accompanying drawings:

[0062] like Figure 1 As shown, a method for measuring the primary air flow rate at the inlet of a coal mill includes:

[0063] Obtain the cold primary air temperature before mixing, the hot primary air temperature before mixing, the hot primary air flow before mixing, and the primary air temperature at the coal mill inlet after mixing;

[0064] The average specific heat capacity before and after hot air mixing and the average specific heat capacity before and after cold air mixing are obtained by obtaining the cold primary air temperature before mixing, the hot primary air temperature before mixing, and the coal mill inlet primary air temperature after mixing, that is:

[0065]

[0066]

[0067] The corresponding functional relationship is specifically:

[0068]

[0069]

[0070] in:

[0071]

[0072]

[0073] Where,

[0074] The temperature of hot primary air before mixing;

[0075] The temperature of the cold primary air before mixing;

[0076] The temperature of primary air at the inlet of coal mill after mixing;

[0077] is the average temperature before and after the cold wind mixes;

[0078] is the average temperature before and after hot air mixing;

[0079] is the average specific heat capacity before and after hot air mixing;

[0080] is the average specific heat capacity before and after cold air mixing.

[0081] By obtaining the cold primary air temperature before mixing, the hot primary air temperature before mixing, the primary air temperature at the coal mill inlet after mixing, the average specific heat capacity before and after hot air mixing, and the average specific heat capacity before and after cold air mixing, the cold primary air flow rate before mixing is obtained according to the principle of energy conservation; specifically:

[0082]

[0083]

[0084]

[0085] Solving the equations together, we can get:

[0086]

[0087] Where,

[0088] The cold air absorbs heat before and after mixing;

[0089] Heat is released to heat the air before and after mixing;

[0090] The cold primary air flow rate before mixing;

[0091] The hot primary air flow rate before mixing;

[0092] The primary air flow rate at the coal mill inlet is obtained by the hot primary air flow rate before mixing and the cold primary air flow rate before mixing, specifically:

[0093]

[0094] Where,

[0095] It is the primary air flow rate at the coal mill inlet after mixing.

[0096] Preferably, in the normal operating range of the coal mill, that is, the cold air temperature at the coal mill inlet is 20-50°C, the hot air temperature is 300-350°C, the primary air temperature after mixing is 200-350°C, and the average specific heat capacity before and after hot air mixing and the average specific heat capacity before and after cold air mixing are approximately the same, that is, , then the primary air flow rate at the coal mill inlet is:

[0097]

[0098] The present invention measures the hot primary air flow rate and hot primary air temperature before mixing, the cold primary air temperature before mixing, and the coal mill inlet primary air temperature after mixing, which are uniform and easier to accurately measure. Through a preset calculation formula, the coal mill inlet primary air flow rate is accurately calculated, effectively solving the problem of inaccurate measurement of the coal mill inlet primary air flow rate. The present invention does not directly obtain the flow rate of the cold primary air, but obtains it by calculation. Because most on-site cold air pipes are relatively compact and the straight pipe sections are short, it is difficult to find a suitable location to install a flow measurement device. In addition, cold air is air temperature regulating air, which usually accounts for a small proportion of the total primary air volume and has large fluctuations, making it difficult to accurately measure. Therefore, directly obtaining the flow rate of the cold primary air is not conducive to the accuracy of the measurement and the simplicity of the system. The method of the present invention is of great significance to the adjustment of the pulverizing system and the safe operation of the boiler.

[0099] like Figure 2 As shown, a system for measuring the primary air flow rate at the inlet of a coal mill comprises:

[0100] Data acquisition module 001 is used to obtain the pre-mixing cold primary air temperature, pre-mixing hot primary air temperature, pre-mixing hot primary air flow rate, and post-mixing coal mill inlet primary air temperature. The data acquisition module includes a pre-mixing hot primary air flow rate measurement device, a pre-mixing hot primary air temperature measurement device, a pre-mixing cold primary air temperature measurement device, and a post-mixing coal mill inlet primary air temperature measurement device. The pre-mixing hot primary air flow rate measurement device and the hot primary air temperature measurement device are located in the hot primary air duct; the pre-mixing cold primary air temperature measurement device is located in the cold primary air duct; and the post-mixing coal mill inlet primary air temperature measurement device is located in the post-mixing coal mill inlet primary air duct. The pre-mixing hot primary air flow rate measurement device is a flow transmitter, and the pre-mixing hot primary air temperature measurement device, the pre-mixing cold primary air temperature measurement device, and the post-mixing coal mill inlet primary air temperature measurement device are all temperature transmitters. The hot primary air flow rate measuring device before mixing and the hot primary air temperature measuring device are installed in the straight pipe section of the hot primary air duct; the cold primary air temperature measuring device before mixing is installed in the straight pipe section of the cold primary air duct; the primary air temperature measuring device at the inlet of the coal mill after mixing is installed in the straight pipe section of the primary air duct at the inlet of the coal mill after mixing.

[0101] Data processing module 002 is used to obtain the average specific heat capacity before and after hot air mixing and the average specific heat capacity before and after cold air mixing by obtaining the cold primary air temperature before mixing, the hot primary air temperature before mixing, the hot primary air flow rate before mixing, and the primary air temperature at the coal mill inlet after mixing, and then obtain the cold primary air flow rate before mixing; and obtain the primary air flow rate at the coal mill inlet by using the hot primary air flow rate before mixing and the cold primary air flow rate before mixing;

[0102] The result display module 003 is used to output the acquired primary air flow rate data at the coal mill inlet and display the primary air flow rate at the coal mill inlet.

[0103] The present invention provides a terminal device. The terminal device includes: a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the method for measuring the primary air flow rate at the inlet of a coal mill according to the present invention. Alternatively, when the processor executes the computer program, it implements the aforementioned method.

[0104] The computer program may be divided into one or more modules / units, which are stored in the memory and executed by the processor to accomplish the present invention.

[0105] The terminal device may be a computing device such as a desktop computer, a notebook computer, a PDA, a cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0106] The processor can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0107] The memory may be used to store the computer programs and / or modules, and the processor implements various functions of the terminal device by running or executing the computer programs and / or modules stored in the memory and calling the data stored in the memory.

[0108] If the module / unit integrated into the terminal device is implemented as a software functional unit and sold or used as a standalone product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention can implement all or part of the processes in the above-mentioned embodiments by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, the computer program can implement the above-mentioned methods. The computer program includes computer program code, which can be in source code form, object code form, executable file, or some intermediate form. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard drive, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signals, telecommunication signals, and software distribution media. It should be noted that the content of the computer-readable medium can be appropriately increased or decreased based on the requirements of legislation and patent practice within a jurisdiction. For example, in some jurisdictions, based on legislation and patent practice, computer-readable media does not include electric carrier signals and telecommunication signals.

[0109] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for measuring the primary air flow rate at the inlet of a coal mill, characterized in that: include: Obtain the cold primary air temperature before mixing, the hot primary air temperature before mixing, the hot primary air flow rate before mixing, and the primary air temperature at the coal mill inlet after mixing; Obtain the average specific heat capacity before and after hot air mixing and the average specific heat capacity before and after cold air mixing by obtaining the cold primary air temperature before mixing, the hot primary air temperature before mixing, and the coal mill inlet primary air temperature after mixing; Obtain the flow rate of the cold primary air before mixing by obtaining the cold primary air temperature before mixing, the hot primary air temperature before mixing, the primary air temperature at the coal mill inlet after mixing, the average specific heat capacity before and after hot air mixing, and the average specific heat capacity before and after cold air mixing; The primary air flow rate of the coal mill inlet is obtained by the hot primary air flow rate before mixing and the cold primary air flow rate before mixing; The specific process of obtaining the average specific heat capacity before and after the hot air is mixed and the average specific heat capacity before and after the cold air is mixed is as follows: in: Where, The temperature of hot primary air before mixing; The temperature of the cold primary air before mixing; The temperature of primary air at the inlet of coal mill after mixing; is the average temperature before and after the cold wind mixes; is the average temperature before and after hot air mixing; is the average specific heat capacity before and after hot air mixing; is the average specific heat capacity before and after cold air mixing; The process of obtaining the cold primary air flow rate before mixing is specifically as follows: Where, The cold primary air flow rate before mixing; The hot primary air flow rate before mixing; The specific process of obtaining the primary air flow rate at the coal mill inlet is as follows: Where, The primary air flow rate at the coal mill inlet after mixing; When the cold air temperature at the coal mill inlet is 20-50℃, the hot air temperature is 300-350℃, and the primary air temperature after mixing is 200-350℃, the primary air flow rate at the coal mill inlet is: 。 2. A system for measuring the primary air flow rate at the inlet of a coal mill for implementing the method for measuring the primary air flow rate at the inlet of a coal mill as claimed in claim 1, characterized in that: include: Data acquisition module, used to obtain the temperature of cold primary air before mixing, the temperature of hot primary air before mixing, the flow rate of hot primary air before mixing, and the temperature of primary air at the coal mill inlet after mixing; a data processing module for obtaining the average specific heat capacity before and after hot air mixing and the average specific heat capacity before and after cold air mixing by obtaining the cold primary air temperature before mixing, the hot primary air temperature before mixing, the hot primary air flow rate before mixing, and the primary air temperature at the coal mill inlet after mixing, thereby obtaining the cold primary air flow rate before mixing; and obtaining the primary air flow rate at the coal mill inlet by obtaining the hot primary air flow rate before mixing and the cold primary air flow rate before mixing; The result display module is used to output the acquired primary air flow rate data at the coal mill inlet and display the primary air flow rate at the coal mill inlet.

3. A system for measuring primary air flow at the coal mill inlet according to claim 2, characterized in that: The data acquisition module includes a hot primary air flow measurement device, a hot primary air temperature measurement device, a cold primary air temperature measurement device and a post-mixing coal mill inlet primary air temperature measurement device; The hot primary air flow measuring device and the hot primary air temperature measuring device are arranged in the hot primary air duct; The cold primary air temperature measuring device is arranged in the cold primary air duct; The device for measuring the temperature of the primary air at the inlet of the mixed coal mill is arranged in the air duct of the primary air at the inlet of the mixed coal mill.

4. A system for measuring primary air flow at the coal mill inlet according to claim 3, characterized in that: The hot primary air flow measuring device and the hot primary air temperature measuring device are installed at the straight pipe section of the hot primary air duct before mixing; the cold primary air temperature measuring device is installed at the straight pipe section of the cold primary air duct before mixing; the primary air temperature measuring device at the coal mill inlet after mixing is installed at the straight pipe section of the primary air duct at the coal mill inlet after mixing.

5. A terminal device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the method according to claim 1 is implemented.

6. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method as claimed in claim 1 is implemented.

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