Primary air powder concentration measuring device and method and heat supply system

Abstract

The invention provides a primary air powder concentration measuring device and method and a heat supply system, and belongs to the technical field of concentration measuration.The method comprises the steps that on the basis of an electrostatic loading system, charge loading treatment is conducted on electrostatic ions on the surfaces of all pulverized coal particles when a power plant is in a low load state, so that all the electrostatic ions reach a saturated state; the total charge quantity of the electrostatic ions reaching the saturation state is measured on the basis of each charge quantity measuring sensor, and charges generated when the electrostatic ions reaching the saturation state flow through are detected on the basis of each signal detection sensor to generate an electric signal; and based on the controller, the pulverized coal mass flow is calculated according to the electric signal generated by the signal detection sensor, and the primary pulverized coal concentration in the pulverized coal pipeline is calculated according to the total charge quantity of the electrostatic ions and the pulverized coal mass flow. According to the scheme, the primary air powder concentration can be accurately measured under the condition of low load of the power plant.

Description

Technical Field

[0001] The present application relates to the technical field of concentration measurement, and in particular to a primary air powder concentration measurement device, method and heating system. Background Art

[0002] In the operation of the boiler in a thermal power plant, the uniformity of the primary air and pulverized coal flow of the pulverized coal burner plays an important role in the safe and economical operation of the boiler. Maintaining the primary and secondary air speeds is a necessary condition for establishing good aerodynamic conditions in the furnace and stable combustion. At present, the measurement method of primary air pulverized coal concentration in the existing technology mainly adopts the sensor charge method.

[0003] However, this measurement method cannot accurately measure the primary air-powder concentration under low load conditions in power plants, the state of boiler combustion cannot be adjusted, and coal powder cannot be evenly distributed in each air-powder pipe. The air-powder in the boiler burner is too small or too large, resulting in low burnout or excessive oxygen combustion in some burners, causing overheating of the superheater or coking of the water-cooled wall.

[0004] Therefore, how to accurately measure the primary air dust concentration under low load conditions in a power plant has become a problem that needs to be solved. Summary of the invention

[0005] The purpose of the present application is to provide a primary air dust concentration measurement device, method and heating system, which can solve the problem in the prior art that the primary air dust concentration cannot be accurately measured under low load conditions in power plants.

[0006] In a first aspect, an embodiment of the present application provides a primary air-powder concentration measuring device, which is arranged on the inner wall of an air-powder duct, wherein the primary air-powder is a mixture of primary air and a plurality of coal powder particles; the device comprises: an electrostatic loading system, a plurality of charge measurement sensors, a plurality of signal detection sensors and a controller; The electrostatic loading system is connected to the first charge measurement sensor, and a signal detection sensor is arranged between every two charge measurement sensors; the electrostatic loading system is used to load the electrostatic ions on the surface of each coal powder particle when the power plant is under low load, so that each electrostatic ion reaches a saturated state; Each charge measurement sensor is used to measure the total charge of the electrostatic ions that have reached a saturated state; each signal detection sensor is used to detect the charge when the electrostatic ions that have reached a saturated state flow through, and generate an electrical signal; The controller is used to calculate the coal powder mass flow rate according to the electrical signal generated by the signal detection sensor, and calculate the primary air-powder concentration in the air-powder pipeline according to the total charge of the electrostatic ions and the coal powder mass flow rate.

[0007] In a possible implementation of the first aspect, the electrostatic loading system includes: a first electrode plate and a second electrode plate; The first electrode plate is arranged on the first side of the inner wall of the air-powder duct, and the second electrode plate is arranged on the second side of the inner wall of the air-powder duct. The first electrode plate and the second electrode plate constitute an electrostatic loading capacitor; the first side of the first electrode plate is connected to the first side of the first charge measurement sensor, and the second side of the second electrode plate is connected to the second side of the first charge measurement sensor.

[0008] In a possible implementation of the first aspect, the electrostatic loading system includes an electrostatic loading ring; the electrostatic loading ring is nested on the inner wall of the air-powder duct, the first side of the electrostatic loading ring is connected to the first side of the first charge measurement sensor, and the second side of the electrostatic loading ring is connected to the second side of the first charge measurement sensor.

[0009] In a possible implementation of the first aspect, each charge measurement sensor includes a first type of metal ring sensor; Each first-class metal ring sensor is nested on the inner wall of the air-powder duct, the first side of the first-class metal ring sensor is connected to the first side of the electrostatic loading system, the second side of the first-class metal ring sensor is connected to the second side of the electrostatic loading system, and a signal detection sensor is arranged between every two first-class metal ring sensors.

[0010] In a possible implementation of the first aspect, each signal detection sensor includes a second type metal ring sensor; each second type metal ring sensor is nested on the inner wall of the air powder duct, and each second type metal ring sensor is arranged between two charge measurement sensors.

[0011] In a possible implementation of the first aspect, the device further includes an electrostatic unloading system; Each charge quantity measuring sensor and each signal detection sensor are arranged between the electrostatic loading system and the electrostatic unloading system; the first side of the electrostatic unloading system is connected to the first side of the last charge quantity measuring sensor, and the second side of the electrostatic unloading system is connected to the second side of the last charge quantity measuring sensor; The electrostatic unloading system is used to unload the charge of the electrostatic ions on the surface of each coal powder particle so that each electrostatic ion reaches an unsaturated state.

[0012] In a possible implementation of the first aspect, the electrostatic unloading system includes: a third electrode plate and a fourth electrode plate; the third electrode plate is arranged on the first side of the inner wall of the air-powder duct, and the fourth electrode plate is arranged on the second side of the inner wall of the air-powder duct, and the first side of the third electrode plate is connected to the first side of the last charge measurement sensor, and the second side of the fourth electrode plate is connected to the second side of the last charge measurement sensor.

[0013] In a possible implementation manner of the first aspect, the device further includes a carbon content detection sensor, and the carbon content detection sensor is used to detect the carbon content in each coal powder particle.

[0014] In a possible implementation manner of the first aspect, the device further includes a water content detection sensor, and the water content detection sensor is used to detect the water content in each coal powder particle.

[0015] In a second aspect, an embodiment of the present application provides a heating system, the system comprising: a raw coal bunker, a coal feeder, a coal mill, an air-powder pipeline, a pulverized coal burner, a boiler, a heating pipeline, and a primary air-powder concentration measuring device according to any one of the first aspects; The raw coal bunker is used to store coal; the coal feeder is used to transport the coal in the raw coal bunker to the coal mill; the coal mill is used to grind the coal to obtain coal powder; the air-powder pipeline is used to transport the primary air-powder to the coal powder burner; The boiler is used to heat the supply water based on the pulverized coal burner to obtain hot water; the heating pipeline is used to transport the hot water to the user; the measuring device is used to measure the primary air powder concentration in the air powder pipeline when the power plant is under low load.

[0016] In a third aspect, an embodiment of the present application provides a method for measuring the concentration of primary air powder, which is implemented based on the primary air powder concentration measuring device of any one of the first aspects, and the method includes: Based on the electrostatic loading system, the electrostatic ions on the surface of each coal powder particle are charged when the power plant is under low load, so that each electrostatic ion reaches a saturated state; Based on each charge amount measuring sensor, the total charge amount of electrostatic ions reaching a saturated state is measured therein, and based on each signal detecting sensor, the charge when the electrostatic ions reaching a saturated state flow through is detected to generate an electrical signal; Based on the controller, the coal powder mass flow rate is calculated according to the electrical signal generated by the signal detection sensor, and the primary air-powder concentration in the air-powder pipeline is calculated according to the total charge of the electrostatic ions and the coal powder mass flow rate.

[0017] In a possible implementation manner of the third aspect, calculating the coal powder mass flow rate according to the electrical signal generated by the signal detection sensor includes: Calculate the time difference between the two signal detection sensors detecting the electrical signals; take the quotient of the distance between the two signal detection sensors and the corresponding time difference as the coal powder flow rate; take the product of the absolute concentration of coal powder, the coal powder flow rate and the cross-sectional area of ​​the air-powder duct as the coal powder mass flow rate.

[0018] In a possible implementation of the third aspect, calculating the primary air-powder concentration in the air-powder pipeline according to the total charge of the electrostatic ions and the coal powder mass flow rate includes: According to the average difference between the total charge amounts of each target and the coal powder mass flow rate, the primary air-powder concentration is calculated. The specific calculation formula is as follows:

[0019] Wherein, the target total charge is the total charge of the electrostatic ions of the target charge measurement sensor, Indicates the primary air powder concentration, Indicates the total charge of the electrostatic ions of the first target charge measurement sensor, Indicates the total charge of the electrostatic ions of the last target charge measurement sensor. Indicates the number of target charge measurement sensors, k The charge-to-mass ratio of the electrostatic ion, f represents the charge of the electrostatic ions before electrostatic loading, d Indicates the mass flow rate of pulverized coal.

[0020] In the present application scheme, the electrostatic loading system charges the electrostatic ions on the surface of each coal powder particle when the power plant is under low load, so that each electrostatic ion is saturated, each charge measurement sensor measures the total charge of the electrostatic ions that have reached the saturated state, each signal detection sensor generates an electrical signal, and the controller calculates the coal powder mass flow rate based on the electrical signal, and then calculates the primary air-powder concentration based on the total charge of the electrostatic ions and the coal powder mass flow rate.

[0021] The application scheme can accurately measure the primary air powder concentration under low load conditions of the power plant, and has strong ease of use and practicality.

[0022] Other features and advantages of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0024] Figure 1 It is a schematic diagram of the overall structure of a primary air powder concentration measuring device provided in an embodiment of the present application; Figure 2 It is a specific structural schematic diagram of the primary air powder concentration measuring device provided in an embodiment of the present application; Figure 3 It is a schematic diagram of the overall structure of the heating system provided in the embodiment of the present application; Figure 4It is a schematic diagram of the steps of a method for measuring air powder concentration provided in an embodiment of the present application. DETAILED DESCRIPTION

[0025] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0026] It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0027] It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the application. As used in this application specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0028] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0029] As used in this specification and the appended claims, the term "if" may be interpreted as "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if [described condition or event] is detected" may be interpreted as meaning "upon determination" or "in response to determining" or "upon detection of [described condition or event]" or "in response to detecting [described condition or event]," depending on the context.

[0030] In addition, in the description of the present application, the terms "first", "second", "third", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0031] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0032] In the present application specification, unless otherwise specified, directional words such as "up, down, left, right" generally refer to the orientation or position relationship shown in the accompanying drawings, or the orientation or position relationship in which the invented product is usually placed when in use.

[0033] In the present application specification, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] In the operation of the boiler in a thermal power plant, the uniformity of the primary air and pulverized coal flow of the pulverized coal burner plays an important role in the safe and economical operation of the boiler. Maintaining the primary and secondary wind speeds is a necessary condition for establishing good aerodynamic conditions in the furnace and stable combustion. Under low load conditions in power plants, due to large deviations from the design value, the boiler cannot adjust its state during combustion, causing overheating of the superheater or coking of the water-cooled wall.

[0035] At present, the measurement and calculation methods of primary air powder concentration include heat balance method and photoelectric measurement method. The heat balance method must make the following assumptions: the system is in an adiabatic state before and after mixing, the temperature of the mixed mixture is consistent, and the specific heat capacity of coal powder is not affected by changes in its composition within a certain range. Photoelectric measurement method: Use a fiber optic probe to introduce the light beam into the measurement area, measure the induction signal of the moving particles to light, and then calculate the signal after photoelectric conversion and analog-to-digital conversion to finally obtain the concentration value of the particles.

[0036] At present, charge method sensors are used, which are mainly divided into three types: insertion type, annular full-section structure and E+C space inclusion structure. Among them, the insertion type sensor, due to the uneven distribution of coal powder concentration on the pipeline cross section, the coal powder concentration data measured by the instrument is different due to different insertion positions in the same cross section.

[0037] The full-section annular measurement sensor, due to the distribution of coal powder in the pipeline cross section, once the center flow is not in the center of the pipeline, and the annular precision measurement principle is the maximum charge potential, if the center flow deviates too much, it will also cause measurement errors.

[0038] However, the measurement method in the prior art cannot accurately measure the primary air-powder concentration under low load conditions in power plants, the state of boiler combustion cannot be adjusted, and coal powder cannot be evenly distributed in each air-powder pipe. The air-powder in the boiler burner is too small or too large, resulting in low burnout or excessive oxygen combustion in some burners, causing overheating of the superheater or coking of the water-cooled wall.

[0039] Therefore, how to accurately measure the primary air dust concentration under low load conditions in a power plant has become a problem that needs to be solved.

[0040] In response to the above-mentioned defects, an embodiment of the present application provides a primary air powder concentration measuring device. When the power plant is under low load, the electrostatic loading system charges the electrostatic ions on the surface of each coal powder particle to saturate each electrostatic ion. Each charge measurement sensor measures the total charge of the electrostatic ions that have reached the saturated state. Each signal detection sensor generates an electrical signal. The controller calculates the coal powder mass flow rate based on the electrical signal, and then calculates the primary air powder concentration based on the total charge of the electrostatic ions and the coal powder mass flow rate.

[0041] The application scheme can accurately measure the primary air powder concentration under low load conditions of the power plant, and has strong ease of use and practicality.

[0042] The structure of the primary air powder concentration measuring device provided in the embodiment of the present application is introduced below through specific embodiments.

[0043] See also Figure 1 , Figure 1 Schematic diagram of the overall structure of the primary air powder concentration measuring device 100 provided in the embodiment of the present application. Figure 1 As shown, the device 100 includes: an electrostatic charging system 110 , a plurality of charge quantity measurement sensors 120 , a plurality of signal detection sensors 130 and a controller 140 .

[0044] In some embodiments, the electrostatic loading system 110 is connected to the first charge measurement sensor 120, and a signal detection sensor 130 is provided between every two charge measurement sensors 120. The electrostatic loading system 110 is used to load the electrostatic ions on the surface of each coal powder particle when the power plant is under low load, so that each electrostatic ion reaches a saturated state.

[0045] Exemplarily, the device 100 has three charge quantity measurement sensors 120 , and a signal detection sensor 130 is provided between the first and second charge quantity measurement sensors 120 and between the second and third charge quantity measurement sensors 120 .

[0046] In some embodiments, each charge quantity measuring sensor 120 is used to measure the total charge quantity of electrostatic ions reaching a saturated state, and each signal detecting sensor 130 is used to detect the charge when electrostatic ions reaching a saturated state flow through, and generate an electrical signal.

[0047] In some embodiments, the controller 140 is used to calculate the coal powder mass flow rate according to the electrical signal generated by the signal detection sensor 130, and then calculate the primary air-powder concentration in the air-powder pipeline according to the total charge of the electrostatic ions and the coal powder mass flow rate.

[0048] See also Figure 2 , Figure 2 Schematic diagram of the specific structure of the primary air powder concentration measuring device provided in the embodiment of the present application. Figure 2 As shown, the electrostatic loading system 110 includes: a first electrode plate and a second electrode plate.

[0049] In some embodiments, the first electrode plate is disposed on a first side of the inner wall of the air-powder duct, and the second electrode plate is disposed on a second side of the inner wall of the air-powder duct, and the first electrode plate and the second electrode plate constitute an electrostatic loading capacitor. The first side of the first electrode plate is connected to the first side of the first charge measurement sensor 120, and the second side of the second electrode plate is connected to the second side of the first charge measurement sensor 120.

[0050] According to one embodiment of the present application, the electrostatic loading system 110 includes an electrostatic loading ring. The electrostatic loading ring is nested on the inner wall of the air powder duct, the first side of the electrostatic loading ring is connected to the first side of the first charge measurement sensor 120, and the second side of the electrostatic loading ring is connected to the second side of the first charge measurement sensor 120.

[0051] According to an embodiment of the present application, each charge measurement sensor 120 includes a first-class metal ring sensor. Each first-class metal ring sensor is nested on the inner wall of the air-powder duct, the first side of the first first-class metal ring sensor is connected to the first side of the electrostatic loading system 110, the second side of the first first-class metal ring sensor is connected to the second side of the electrostatic loading system 110, and a signal detection sensor 130 is arranged between every two first-class metal ring sensors.

[0052] In one embodiment, the first type of metal ring sensor is a wider metal ring sensor.

[0053] According to an embodiment of the present application, each signal detection sensor 130 includes a second type metal ring sensor. Each second type metal ring sensor is embedded on the inner wall of the air powder duct, and each second type metal ring sensor is disposed between two charge measurement sensors 120 .

[0054] In one embodiment, the second type of metal ring sensor is a narrow ring sensor.

[0055] According to one embodiment of the present application, the device further includes an electrostatic unloading system 150. Each charge quantity measurement sensor 120 and each signal detection sensor 130 are arranged between the electrostatic loading system 110 and the electrostatic unloading system 150, the first side of the electrostatic unloading system 150 is connected to the first side of the last charge quantity measurement sensor 120, and the second side of the electrostatic unloading system 150 is connected to the second side of the last charge quantity measurement sensor 120.

[0056] In some embodiments, the electrostatic unloading system 150 is used to unload the charge of the electrostatic ions on the surface of each coal powder particle so that each electrostatic ion reaches an unsaturated state.

[0057] According to one embodiment of the present application, the electrostatic unloading system 150 includes: a third electrode plate and a fourth electrode plate. The third electrode plate is arranged on the first side of the inner wall of the air-powder duct, the fourth electrode plate is arranged on the second side of the inner wall of the air-powder duct, the first side of the third electrode plate is connected to the first side of the last charge measurement sensor 120, and the second side of the fourth electrode plate is connected to the second side of the last charge measurement sensor 120.

[0058] like Figure 2 As shown, according to one embodiment of the present application, the device 100 further includes a carbon content detection sensor 160, and the carbon content detection sensor 160 is used to detect the carbon content in each coal powder particle.

[0059] like Figure 2 As shown, according to one embodiment of the present application, the device 100 further includes a water content detection sensor 170, and the water content detection sensor 170 is used to detect the water content in each coal powder particle.

[0060] See also Figure 3 , Figure 3 Schematic diagram of the overall structure of the heating system 200 provided in the embodiment of the present application. Figure 3 As shown, the system 200 includes: a raw coal bunker 210, a coal feeder 220, a coal mill 230, an air-powder duct, a pulverized coal burner 240, a boiler 250, a heating duct and a primary air-powder concentration measuring device 100.

[0061] In some embodiments, the raw coal bin 210 is used to store coal, the coal feeder 220 is used to transport the coal in the raw coal bin 210 to the coal mill 230, the coal mill 230 is used to grind the coal to obtain coal powder, and the air-powder pipeline is used to transport the primary air-powder to the coal powder burner 240.

[0062] In some embodiments, the boiler 250 is used to heat the supply water to obtain hot water based on the pulverized coal burner 240. The heating pipeline is used to transport the hot water to the user, and the measuring device 100 is used to measure the primary air powder concentration in the air powder pipeline when the power plant is under low load.

[0063] See also Figure 4 , Figure 4 Schematic diagram of the steps of the primary air powder concentration measurement method provided in the embodiment of the present application. The method is implemented based on the primary air powder concentration measurement device 100. Figure 4 As shown, the method may include the following steps: S401, based on the electrostatic loading system 110, when the power plant is under low load, the electrostatic ions on the surface of each coal powder particle are charged to make each electrostatic ion reach a saturated state.

[0064] S402 , based on each charge amount measuring sensor 120 , the total charge amount of electrostatic ions reaching a saturated state is measured, and based on each signal detecting sensor 130 , the charge when the electrostatic ions reaching a saturated state flow through is detected to generate an electrical signal.

[0065] S403, based on the controller 140, the coal powder mass flow rate is calculated according to the electrical signal generated by the signal detection sensor 130, and the primary air-powder concentration in the air-powder pipeline is calculated according to the total charge of the electrostatic ions and the coal powder mass flow rate.

[0066] According to an embodiment of the present application, calculating the coal powder mass flow rate according to the electrical signal generated by the signal detection sensor 130 may include the following steps: The time difference between the two signal detection sensors 130 detecting the electrical signal is calculated, and the quotient of the distance between the two signal detection sensors 130 and the corresponding time difference is used as the pulverized coal flow rate. The product of the absolute concentration of pulverized coal, the pulverized coal flow rate and the cross-sectional area of ​​the air-powder pipeline is used as the pulverized coal mass flow rate.

[0067] In some embodiments, two metal narrow ring sensors are installed in the coal powder pipeline along the flow direction, and two random electrical signals generated when the air and powder flow through the metal narrow ring sensors can be received. Since the two metal narrow ring sensors are very close to each other, the two random electrical signals generated are very similar, but there is a time difference. This time difference can be obtained through relevant calculations, and the average coal powder flow rate in the air and powder pipeline can be obtained by dividing the distance between the two metal narrow ring sensors by this time difference.

[0068] According to an implementation of the present application, the primary air-powder concentration in the air-powder pipeline is calculated based on the total charge of the electrostatic ions and the coal powder mass flow rate, which may include the following steps: According to the average difference between the total charge amounts of each target and the coal powder mass flow rate, the primary air-powder concentration is calculated. The specific calculation formula is as follows:

[0069] The target total charge is the total charge of the electrostatic ions of the target charge measurement sensor 120. Indicates the primary air powder concentration, represents the total charge amount of the electrostatic ions of the first target charge amount measurement sensor 120, represents the total charge of the electrostatic ions of the last target charge measurement sensor 120, represents the number of target charge amount measuring sensors 120, k The charge-to-mass ratio of the electrostatic ion, f represents the charge of the electrostatic ions before electrostatic loading, d Indicates the mass flow rate of pulverized coal.

[0070] This application scheme adopts electrostatic loading enhancement technology. According to the flow characteristics of the wind-coal mixture, the electrostatic ions on the surface of the coal powder are in an unsaturated state after the two-phase flow (air-powder mixing). Electrodes are installed in front of the device 100. According to the principle of electrostatic loading technology capacitance, a spatial inclusion structure sensor is used to detect the flow rate, concentration, mass flow rate, particle fineness, calorific value and water content of the coal powder.

[0071] When the specific value is measured, the particle surface electrostatic unloading technology is used to make the coal powder change to a normal two-phase flow state. When the unit is under low load, the actual characteristics of the air powder concentration can be reflected, so that the power plant operators can observe the actual state for leveling.

[0072] This application is mainly to accurately measure the carbon content, water content, particle concentration and flow rate of coal powder under low load conditions in power plants. The higher the carbon content, the smaller the electrostatic binding force; the higher the water content, the less electrostatic charge; the larger the surface area of ​​the coal powder particles, the more charge; the higher the magnetic insulation of the capacitor diaphragm, the greater the signal. Different factors may affect the amount of charge carried by the coal powder particles, resulting in inaccurate measurement results. In order to ensure accurate measurement, two electrode plates are installed in front of the measuring device 100, and the electrostatic loading technology can effectively ensure that the charge carried by the coal powder particles is full.

[0073] In the present application scheme, the electrostatic loading system 110 charges the electrostatic ions on the surface of each coal powder particle when the power plant is under low load, so that each electrostatic ion is saturated, each charge measurement sensor 120 measures the total charge of the electrostatic ions that have reached the saturated state, each signal detection sensor 130 generates an electrical signal, and the controller 140 calculates the coal powder mass flow rate based on the electrical signal, and then calculates the primary air-powder concentration based on the total charge of the electrostatic ions and the coal powder mass flow rate.

[0074] The application scheme can accurately measure the primary air powder concentration under low load conditions of the power plant, and has strong ease of use and practicality.

[0075] The application scheme can accurately reflect the real-time parameters of the pulverized coal pipeline at low load, helping operators to make better adjustments.

[0076] This application solution can solve the following problems: (1) When the power plant boiler is under low load, the air flow rate, flow velocity, coal powder particle concentration, and the combustion heat energy of each burner are not measured. As a result, the burner state cannot be adjusted under various load conditions, and combustion problems such as overheating and coking cannot be solved. At the same time, the frequent adjustment of the boiler to adapt to the load makes the low-load stable combustion ability poor.

[0077] (2) In the current dilute phase transportation of coal powder particles, tiny solid particles are unevenly distributed in the transportation pipeline, resulting in inaccurate electrostatic potential. The concentration of coal powder particles in the dilute phase transportation is too small to cause a low potential that cannot be measured by ordinary electrostatic potentiometers. The particle concentration that can be measured by this application is less than 50kg / m 3 .

[0078] (3) The low particle concentration or high water content of the particles in the dilute phase transportation of coal powder reduces the ability of the particle surface to carry electrostatic charge, resulting in a low potential that cannot be measured by ordinary electrostatic potentiometers. This application scheme can improve the detection capability, and the minimum measurable particle temperature in the dilute phase transportation of coal powder can be as low as 50°C, and the maximum measurable raw coal moisture content can reach 45%.

[0079] This application scheme adopts electrostatic loading enhancement technology to solve the problem of inaccurate measurement of coal powder concentration and flow rate in the dilute phase state. Under low load conditions of power plants, the coal powder concentration can be accurately measured, allowing the power plant to make precise adjustments based on actual conditions.

[0080] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0081] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0082] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A primary air powder concentration measuring device, characterized in that: It is arranged on the inner wall of the air-powder pipeline, and the primary air-powder is a mixture of primary air and a plurality of coal powder particles; the device comprises: an electrostatic loading system, a plurality of charge measurement sensors, a plurality of signal detection sensors and a controller; The electrostatic loading system is connected to the first charge measurement sensor, and a signal detection sensor is arranged between every two charge measurement sensors; the electrostatic loading system is used to load the electrostatic ions on the surface of each coal powder particle when the power plant is under low load, so that each electrostatic ion reaches a saturated state; Each charge measurement sensor is used to measure the total charge of the electrostatic ions that have reached a saturated state; each signal detection sensor is used to detect the charge when the electrostatic ions that have reached a saturated state flow through, and generate an electrical signal; The controller is used to calculate the coal powder mass flow rate according to the electrical signal generated by the signal detection sensor, and calculate the primary air-powder concentration in the air-powder pipeline according to the total charge of the electrostatic ions and the coal powder mass flow rate.

2. The primary air powder concentration measuring device according to claim 1, characterized in that: The electrostatic loading system comprises: a first electrode plate and a second electrode plate; The first electrode plate is arranged on a first side of the inner wall of the air-powder duct, and the second electrode plate is arranged on a second side of the inner wall of the air-powder duct, and the first electrode plate and the second electrode plate constitute an electrostatic loading capacitor; The first side of the first electrode plate is connected to the first side of the first charge amount measuring sensor, and the second side of the second electrode plate is connected to the second side of the first charge amount measuring sensor.

3. The primary air powder concentration measuring device according to claim 1 or 2, characterized in that: The electrostatic loading system includes an electrostatic loading ring; The electrostatic loading ring is nested on the inner wall of the air-powder duct, the first side of the electrostatic loading ring is connected to the first side of the first charge measurement sensor, and the second side of the electrostatic loading ring is connected to the second side of the first charge measurement sensor.

4. The primary air powder concentration measuring device according to claim 1, characterized in that: Each charge quantity measurement sensor includes a first type metal ring sensor; Each first-class metal ring sensor is nested on the inner wall of the air-powder duct, the first side of the first-class metal ring sensor is connected to the first side of the electrostatic loading system, the second side of the first-class metal ring sensor is connected to the second side of the electrostatic loading system, and a signal detection sensor is arranged between every two first-class metal ring sensors.

5. The primary air powder concentration measuring device according to claim 1, characterized in that: Each signal detection sensor includes a second type metal ring sensor; Each second type metal ring sensor is nested on the inner wall of the air powder duct, and each second type metal ring sensor is arranged between two charge quantity measurement sensors.

6. The primary air powder concentration measuring device according to claim 1 or 4, characterized in that: The device also includes a static unloading system; Each charge quantity measuring sensor and each signal detection sensor are arranged between the electrostatic loading system and the electrostatic unloading system; the first side of the electrostatic unloading system is connected to the first side of the last charge quantity measuring sensor, and the second side of the electrostatic unloading system is connected to the second side of the last charge quantity measuring sensor; The electrostatic unloading system is used to unload the charge of the electrostatic ions on the surface of each coal powder particle, so that each electrostatic ion reaches an unsaturated state.

7. The primary air powder concentration measuring device according to claim 6, characterized in that: The electrostatic unloading system comprises: a third electrode plate and a fourth electrode plate; The third electrode plate is arranged on the first side of the inner wall of the air-powder duct, the fourth electrode plate is arranged on the second side of the inner wall of the air-powder duct, the first side of the third electrode plate is connected to the first side of the last charge measurement sensor, and the second side of the fourth electrode plate is connected to the second side of the last charge measurement sensor.

8. The primary air powder concentration measuring device according to claim 1, characterized in that: The device also includes a carbon content detection sensor, which is used to detect the carbon content in each coal powder particle.

9. The primary air powder concentration measuring device according to claim 1 or 8, characterized in that: The device also includes a water content detection sensor, which is used to detect the water content in each coal powder particle.

10. A heating system, characterized in that: The system comprises: a raw coal bunker, a coal feeder, a coal mill, an air-powder pipeline, a pulverized coal burner, a boiler, a heating pipeline, and a primary air-powder concentration measuring device as described in any one of claims 1 to 9; The raw coal bunker is used to store coal; the coal feeder is used to transport the coal in the raw coal bunker to the coal mill; the coal mill is used to grind the coal to obtain coal powder; the air-powder pipeline is used to transport the primary air-powder to the coal powder burner; The boiler is used to heat the supply water based on the pulverized coal burner to obtain hot water; the heating pipeline is used to transport the hot water to the user; the measuring device is used to measure the primary air powder concentration in the air powder pipeline when the power plant is under low load.

11. A method for measuring primary air powder concentration, characterized in that: The method is implemented based on the primary air powder concentration measuring device according to any one of claims 1 to 9, comprising: Based on the electrostatic loading system, the electrostatic ions on the surface of each coal powder particle are charged when the power plant is under low load, so that each electrostatic ion reaches a saturated state; Based on each charge amount measuring sensor, the total charge amount of electrostatic ions reaching a saturated state is measured therein, and based on each signal detecting sensor, the charge when the electrostatic ions reaching a saturated state flow through is detected to generate an electrical signal; Based on the controller, the coal powder mass flow rate is calculated according to the electrical signal generated by the signal detection sensor, and the primary air-powder concentration in the air-powder pipeline is calculated according to the total charge of the electrostatic ions and the coal powder mass flow rate.

12. The primary air powder concentration measurement method according to claim 11, characterized in that: The coal powder mass flow rate is calculated based on the electrical signal generated by the signal detection sensor, including: Calculate the time difference between two signal detection sensors detecting electrical signals; The quotient of the distance between the two signal detection sensors and the corresponding time difference is used as the coal powder flow rate; The product of the absolute concentration of coal powder, the flow rate of the coal powder and the cross-sectional area of ​​the air-powder duct is taken as the mass flow rate of the coal powder.

13. The primary air powder concentration measurement method according to claim 11 or 12, characterized in that: According to the total charge of the electrostatic ions and the coal powder mass flow rate, the primary air-powder concentration in the air-powder pipeline is calculated, including: The primary air powder concentration is calculated based on the average difference between each target total charge and the coal powder mass flow rate. The specific calculation formula is as follows: Wherein, the target total charge is the total charge of the electrostatic ions of the target charge measurement sensor, Indicates the primary air powder concentration, Indicates the total charge of the electrostatic ions of the first target charge measurement sensor, Indicates the total charge of the electrostatic ions of the last target charge measurement sensor. Indicates the number of target charge measurement sensors, k The charge-to-mass ratio of the electrostatic ion, f represents the charge of the electrostatic ions before electrostatic loading, d Indicates the mass flow rate of pulverized coal.

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