Measuring system and method for determining internal temperature of accumulated dust and location of heat source

Abstract

A kind of measuring system and method for determining the internal temperature of accumulated dust and the location of heat source, the system: support platform on the upper end of rack is provided with mounting hole;Heat transfer plate is installed above mounting hole surrounded by heat insulation ring, the upper surface of which is provided with bearing cylinder, and the lower surface is provided with heating resistance wire;A plurality of first thermocouples are arranged in the middle section inside the bearing cylinder;A plurality of second thermocouples are installed on the heat transfer plate;Temperature measuring device is arranged on the periphery of rack;Thermal image acquisition device is arranged above the bearing cylinder;Method: establish conduction-heat convection model;The discrete equation of conduction-heat convection model is obtained through temperature experiment, and the characteristic parameters inherent to dust, such as thermal conductivity coefficient, are calculated for different dust;The internal temperature of any accumulated dust and the location of heat source are measured and determined. The system can reveal the temperature transfer law inside the accumulated dust, and the method can measure the temperature data and internal heat source location information of any accumulated dust.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of dust monitoring, and particularly relates to a measuring and calculating system and method for measuring internal temperature and heat source position of accumulated dust. BACKGROUND

[0002] In industrial production, accumulated dust may be slowly oxidized, such as coal, metal dust, and the oxidation reaction generates heat, leading to heat accumulation, which in turn causes temperature rise, and when the temperature rises to a certain threshold, it can ignite and explode combustible dust, thereby causing serious safety production accidents. At present, industrial dust explosion accidents occur frequently, causing serious personnel injury and economic loss. Therefore, monitoring the internal temperature of accumulated dust and locating the position of the internal heat source are of great significance for effectively reducing dust explosion accidents and determining safety production. However, the traditional method for monitoring the internal temperature of dust relies on limited thermocouple measurement points, and thus cannot comprehensively reflect the temperature distribution inside the dust. Therefore, it is urgent to provide a measuring and calculating system and method that can calculate the three-dimensional temperature field inside the dust in real time and locate the internal heat source position. SUMMARY

[0003] In view of the problems existing in the prior art, the present application provides a measuring and calculating system and method for measuring internal temperature and heat source position of accumulated dust, which has simple structure and low manufacturing cost, can help reveal the temperature transfer law inside the accumulated dust, and can help determine the temperature of each part of the accumulated dust and the position of the internal heat source, thereby effectively reducing the probability of dust explosion accidents. The method can efficiently and accurately calculate the temperature data of each part inside the accumulated dust and the position information of the internal heat source, and can realize scientific monitoring of the temperature data of any accumulated dust.

[0004] To achieve the above purpose, the present application provides a measuring and calculating system for measuring internal temperature and heat source position of accumulated dust, comprising a bottom fixed table, a rack, a heat insulation ring, a heat transfer plate, a bearing cylinder, a heating assembly, a vertical support, a stay wire, a first thermocouple, a second thermocouple, a temperature measuring device, a thermal image acquisition device and a data processing terminal.

[0005] The lower end of the rack is fixedly installed on the center area of the upper end of the bottom fixed table, and the upper end has a horizontal support platform, and a mounting hole is formed in the center area of the support platform;

[0006] The hole diameter of the inner hole of the heat insulation ring is matched with the outer diameter of the mounting hole, the heat insulation ring is fixedly installed on the support platform, and the inner hole thereof is aligned with the mounting hole;

[0007] The outer diameter of the heat transfer plate is matched with the size of the inner hole of the heat insulation ring, and the heat transfer plate is fixedly installed in the inner hole of the heat insulation ring;

[0008] The lower open end of the bearing cylinder is fixedly connected with the upper end surface of the heat transfer plate, two through holes are oppositely arranged at the left and right ends of the middle section of the bearing cylinder, and the inside of the bearing cylinder is filled with accumulated dust;

[0009] The heat assembly comprises a heating power supply, a temperature controller and a heating resistance wire, the heating resistance wire is arranged on the lower end surface of the heat transfer plate in a distributed manner, and is connected with the heating power supply through the temperature controller;

[0010] The two vertical supporting members are oppositely arranged on the left and right sides of the rack, and the lower ends thereof are fixedly connected with the upper end surface of the bottom fixed table;

[0011] The pull wire is transversely arranged in the two through holes on the bearing cylinder, and the two ends thereof are respectively connected with the upper portions of the two vertical supporting members;

[0012] A plurality of first thermocouples are sequentially and spacedly arranged in the left-right direction in the inside of the bearing cylinder and are installed on the pull wire, wherein the two first thermocouples at the two ends in the left-right direction are respectively connected with the left side wall and the right side wall of the bearing cylinder;

[0013] A plurality of second thermocouples are correspondingly arranged below the plurality of first thermocouples and are attached to the upper end surface of the heat transfer plate;

[0014] The temperature measuring device is arranged on the periphery of the rack and is used for collecting temperature signals in the environment in real time;

[0015] The thermal image acquisition device is arranged above the bearing cylinder, the acquisition surface thereof is parallel to the upper surface of the accumulated dust to be measured, and is used for generating a temperature image by detecting infrared radiation of the accumulated dust;

[0016] The data processing terminal is connected with the plurality of first thermocouples, the plurality of second thermocouples, the temperature controller, the temperature measuring device and the thermal image acquisition device.

[0017] Further, in order to make the vertical support have elastic support ability, and at the same time, in order to facilitate the adjustment of the support height, the vertical support comprises a lower support column, a middle section connecting spring, an upper support column, a height adjustment sleeve and a connecting ear plate, the lower end of the lower support column is fixedly connected with the upper end of the bottom fixed table, the lower end of the middle section connecting spring is fixedly connected with the upper end of the lower support column, the upper support column is provided with external thread structure throughout the column body, and the lower end of the upper support column is fixedly connected with the upper end of the middle section connecting spring, the inner diameter of the height adjustment sleeve is matched with the outer diameter of the upper support column, the internal thread structure is arranged in the height adjustment sleeve corresponding to the external thread structure, and the height adjustment sleeve is sleeved on the outside of the upper support column through thread cooperation; the outer end of the connecting ear plate is fixedly connected with one side of the upper part of the height adjustment sleeve, the inner end of the connecting ear plate is provided with a wire passing hole, and the connecting ear plate is connected with the pull wire through the wire passing hole. In order to facilitate manual adjustment of the height of the height adjustment sleeve, an adjusting handle can be fixedly connected with the upper end of the height adjustment sleeve.

[0018] Further, in order to ensure the accuracy of the measurement, and at the same time, in order to ensure the high efficiency of heat transfer, the material of the bearing cylinder and the heat transfer plate is the same, and is made of metal heat transfer material.

[0019] As a preferred, the data processing terminal is an industrial computer.

[0020] In the application, a mounting hole is formed in the center of the support platform, and at the same time, the heat transfer plate is fixedly installed in the area where the mounting hole is located by using the heat insulation ring. On this basis, the heating resistance wire is laid on the lower surface of the heat transfer plate. In this way, only efficient heating of the heat transfer plate is performed during heating, ensuring the efficiency of heating, and at the same time, the heat on the heat transfer plate cannot be transmitted to the surrounding objects, ensuring the stability of the heat on the heat transfer plate and the bearing cylinder, which is beneficial to ensure the accuracy of the test data, and thus can help to obtain an accurate heat conduction-heat convection model. The heating resistance wire is connected with the heating power source through the temperature controller, which can facilitate the use of the temperature controller to control the on-off operation of the heating resistance wire, and at the same time, the temperature controller can be used to control the heating temperature range of the heating resistance wire. Two through holes are formed in the left and right opposite sides of the middle section of the bearing cylinder, and two vertical supports are installed on the left and right sides of the rack. After the pull wire passes through the two through holes and is connected with the two vertical supports, the pull wire can be stably arranged in the middle section of the bearing cylinder. Therefore, the pull wire can be used to provide an installation basis for the plurality of first thermocouples. In this way, after the inside of the bearing cylinder is filled with dust, the plurality of first thermocouples can be used to effectively monitor the temperature of different positions inside the accumulated dust. In addition, the two first thermocouples located at the two ends in the left-right direction are connected with the left side wall and the right side wall of the bearing cylinder, respectively, which can ensure that the two first thermocouples can effectively monitor the temperature of the side edge of the accumulated dust. A plurality of second thermocouples are installed on the heat transfer plate in the internal area of the bearing cylinder and correspond to the plurality of first thermocouples. After the inside of the bearing cylinder is filled with dust, the plurality of second thermocouples can be used to effectively monitor the temperature of the lower surface of the accumulated dust. By arranging the temperature acquisition device on the periphery of the rack, the temperature data in the environment can be monitored in real time. By arranging the thermal image acquisition device above the bearing cylinder, the thermal image of the upper surface of the accumulated dust can be acquired in real time, which is beneficial to obtain the temperature data of the upper surface of the accumulated dust. By cooperating the first thermocouple, the second thermocouple, the temperature acquisition device and the thermal image acquisition device, and combining the temperature conduction theory, the temperature conduction test can be completed, and a certain heat conduction-heat convection model can be obtained, which can provide reliable technical support for reliable monitoring of the internal temperature of any accumulated dust and positioning of the heat source position.

[0021] The system has simple structure and low manufacturing cost, which can help to reveal the temperature transmission rule inside the accumulated dust, and can help to determine the temperature of each part of the accumulated dust and the position of the internal heat source, thereby effectively reducing the probability of dust explosion accidents and greatly improving the safety factor of production operation.

[0022] The application also provides a method for measuring the internal temperature and heat source position of the accumulated dust, which adopts a measuring system for measuring the internal temperature and heat source position of the accumulated dust, and comprises the following steps:

[0023] Step one: build the theoretical equation of heat conduction-heat convection model;

[0024] S11: build the heat conduction model inside the accumulated dust according to formula (1);

[0025]

[0026] In the formula, T is the temperature, t is the time, a is the thermal diffusion coefficient, and g(x, y, z, t) is the heat generation rate of the internal heat source per unit volume;

[0027] S12: build the heat convection model of the dust surface and air;

[0028] S12-1: for the upper surface of the accumulated dust, establish the convective heat transfer boundary condition according to formula (2);

[0029]

[0030] In the formula, is the derivative of temperature in the boundary normal direction, k is the thermal conductivity, h is the convective heat transfer coefficient, and T air is the air temperature;

[0031] S12-2: for the lower surface and side surface of the accumulated dust, their temperatures are the same as that of the bearing cylinder (5);

[0032] Step two: use finite difference method to determine the parameters in the heat conduction-heat convection model;

[0033] S21: discretize the accumulated dust in the bearing cylinder into a three-dimensional grid, where in the radial direction r, from the center of the ring r=0 to the edge of the ring r=R, the step size is Δr; in the angular direction θ, from 0 to 2π, the step size is Δθ; in the axial direction z, from the bottom of the dust z=0 to the top of the dust z=H, the step size is Δz;

[0034] S22: discretization of the heat conduction model; based on the heat conduction equation in cylindrical coordinates, discretize formula (1) to obtain the discretization equation of the heat conduction model, as shown in formula (3);

[0035]

[0036] In the formula, represents the temperature of the nth time step grid point (r i ,θ j ,z k ); Δt is the time step; Δr, Δθ, and Δz are the grid step sizes in the radial, angular, and axial directions, respectively;

[0037] S23: Discretization of the heat convection model to obtain the discretization equation of the heat convection model;

[0038] S23-1: Discretization of formula (2) for the upper surface of the accumulated dust to obtain the discretization equation of the upper boundary heat convection model, as shown in formula (4);

[0039]

[0040] wherein, N Z is the grid index of the upper surface of the dust;

[0041] S23-2: According to formula (5) and formula (6), respectively, the discretization equations of the lower boundary and side heat convection models for the lower surface and side surface of the accumulated dust are obtained;

[0042]

[0043] wherein, T plate is the temperature of the bearing cylinder, and N r is the radial grid index of the edge of the bearing cylinder;

[0044] S24: Perform a standard temperature hot plate experiment on the accumulated dust, and collect the dust surface temperature data and the temperature data of several monitoring points inside the dust;

[0045] S24-1: The inside of the bearing cylinder is paved with the dust to be tested, and the thickness of the dust layer in the bearing cylinder is ensured to be uniform, forming the accumulated dust to be tested;

[0046] S24-2: The temperature controller is started to work by the data processing terminal, so that the heating power supply supplies power to the heating resistance wire, and the temperature controller controls the heating temperature of the heating resistance wire, so that the temperature of the heat transfer plate is constant in the preset temperature range;

[0047] The first temperature signals inside the dust layer are collected by the multiple first thermocouples located in the middle section of the bearing cylinder in real time, and are sent to the data processing terminal. The second temperature signals on the surface of the heat transfer plate are collected by the multiple second thermocouples located at the bottom of the bearing cylinder in real time, and are sent to the data processing terminal. The environmental temperature signals are collected by the temperature measuring device in real time, and are sent to the data processing terminal. The data processing terminal obtains the first temperature data, the second temperature data and the environmental temperature data according to the first temperature signals and the second temperature signals, respectively;

[0048] At the same time, the infrared radiation of the accumulated dust is detected in real time by the thermal image acquisition device, and a temperature image is generated, which is then sent to the data processing terminal. The data processing terminal obtains the upper surface temperature data of the dust according to the temperature image;

[0049] S24-3: The data processing terminal divides the obtained plurality of first temperature data and plurality of second temperature data according to the position information of the plurality of first thermocouples and the position information of the plurality of second thermocouples 4, and respectively obtains the internal temperature data, the side surface temperature data and the lower surface temperature data of the accumulated dust;

[0050] S25: The temperature conduction theory numerical calculation is performed; the obtained internal temperature data is input into the discretization equation of the heat conduction model, and the obtained upper surface temperature data, side surface temperature data and lower surface temperature data are input into the discretization equation of the heat convection model as boundary conditions, and the thermal conductivity k, the convective heat transfer coefficient h and the thermal diffusivity a of the dust to be measured are determined by calculation, and then the discretization equation of the heat conduction model and the discretization equation of the heat convection model of the dust to be measured are obtained;

[0051] Step three: calculate the internal temperature of the arbitrary accumulated dust and determine the position of the internal heat source;

[0052] S31: A plurality of temperature sensors are buried at the key points in the arbitrary accumulated dust;

[0053] S32: The laser scanner is used to scan the arbitrary accumulated dust to obtain the three-dimensional surface data of the arbitrary accumulated dust, and the three-dimensional surface data is sent to the data processing terminal; the data processing terminal generates a three-dimensional geometric model of the arbitrary accumulated dust based on the three-dimensional surface data, and discretizes the three-dimensional form of the arbitrary accumulated dust into a finite element network or a finite difference network to obtain a three-dimensional grid of the arbitrary accumulated dust, and determines the coordinates (i, j, k) of each point;

[0054] S33: The infrared thermal imager is used to shoot the temperature distribution of the surface of the arbitrary accumulated dust, and the temperature data of the surface of the arbitrary accumulated dust is sent to the data processing terminal; the temperature sensor is used to collect the key point temperature signal in real time and send it to the data processing terminal, and the data processing terminal obtains the key point temperature data according to the key point temperature signal;

[0055] S34: According to the temperature data of the surface of the arbitrary accumulated dust, the grid point temperature of the outer surface in the three-dimensional grid is fixed as a known value T boundary ;

[0056] S35: The key point temperature data is brought into the discretization equation of the heat conduction model to establish the Laplace equation as shown in formula (7);

[0057]

[0058] S36: solving formula (7) to obtain the temperature of each place inside the arbitrary accumulated dust, and inversely fitting to calculate the heat source position inside the arbitrary accumulated dust, and establishing the three-dimensional temperature field of the accumulated dust based on the temperature data of each place inside, the heat source position information inside, outputting the temperature data of each place inside, the heat source position information inside and the three-dimensional temperature field to the visualization terminal, and performing real-time display of the temperature data of each place inside, the heat position information inside and the three-dimensional temperature field through the visualization terminal.

[0059] As a preferred, in S12 of step one, the discretization network is hexahedron or tetrahedron.

[0060] As a preferred, in S36 of step three, the internal arbitrary point temperature is calculated by using the thermodynamic iteration method or the high-efficiency algorithm.

[0061] As a preferred, in S36 of step three, the visualization terminal performs real-time display in the form of thermal imaging or three-dimensional temperature cloud chart.

[0062] The application provides a three-dimensional temperature field real-time calculation method for accumulated dust based on experimental data and heat conduction-heat convection model, first, the theoretical equation of the heat conduction-heat convection model is constructed, then, the heat conductivity coefficient k, the convection heat transfer coefficient h and the thermal diffusion coefficient a of the current dust to be measured are determined by combining the finite difference method with the standard temperature hot plate experiment, since the heat conductivity coefficient k, the convection heat transfer coefficient h and the thermal diffusion coefficient a are related to the material itself, the composition, structure, density, temperature and humidity of different materials will affect the specific values of the above coefficients, therefore, before the temperature of the arbitrary accumulated dust is monitored, the heat conductivity coefficient k, the convection heat transfer coefficient h and the thermal diffusion coefficient a of the current dust to be measured are determined through the standard temperature hot plate experiment, so that the discretization equation of the heat conduction model and the discretization equation of the heat convection model suitable for the current dust to be measured can be obtained, ensuring that the temperature of the arbitrary accumulated dust can be monitored more accurately and efficiently subsequently, then, based on the key point temperature data obtained by the temperature sensor buried in the key points inside the arbitrary accumulated dust and the temperature distribution of the surface of the arbitrary accumulated dust obtained by the infrared thermal imager, the Laplace equation can be constructed by combining the discretization equation of the heat conduction model, the temperature distribution of the arbitrary point inside the arbitrary accumulated dust can be deduced by solving the Laplace equation, so that the temperature data of each place inside the arbitrary accumulated dust can be calculated accurately and efficiently, at the same time, the heat source position inside the arbitrary accumulated dust can be calculated inversely, and the three-dimensional temperature field of the accumulated dust can be established based on the temperature data of each place inside and the heat source position information inside, so that the scientific monitoring of the temperature data of the arbitrary accumulated dust can be realized, thereby the probability of dust explosion accidents can be effectively reduced, and the safety factor of production operation can be greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0063] Figure 1 is a structural schematic diagram of the measuring system in the application;

[0064] Figure 2 is a top view of Figure 1 ;

[0065] Figure 3 is a principle block diagram of the circuit principle part in the application.

[0066] In the figure: 1, heat insulation ring, 2, heat transfer plate, 3, first thermocouple, 4, second thermocouple, 5, bearing cylinder, 6, heating resistance wire, 7, thermal image acquisition device, 8, temperature measuring device, 9, bottom fixing table, 10, vertical support, 11, lower support column, 12, middle section connecting spring, 13, upper support column, 14, connecting ear plate, 15, rack, 16, support platform, 17, stay wire, 18, height adjusting sleeve. DETAILED DESCRIPTION

[0067] The application will be further described below.

[0068] As shown in Figures 1 to 3 , the application provides a measuring system for measuring the internal temperature of accumulated dust and the position of heat source, comprising a bottom fixing table 9, a rack 15, a heat insulation ring 1, a heat transfer plate 2, a bearing cylinder 5, a heating assembly, a vertical support 10, a stay wire 17, a first thermocouple 3, a second thermocouple 4, a temperature measuring device 8, a thermal image acquisition device 7 and a data processing terminal;

[0069] The lower end of the rack 15 is fixedly installed on the central area of the upper end of the bottom fixing table 9, the upper end of the rack 15 has a horizontal support platform 16, and a mounting hole is formed in the central area of the support platform 16;

[0070] The hole diameter of the inner hole of the heat insulation ring 1 is matched with the outer diameter of the mounting hole, the heat insulation ring 1 is fixedly installed on the support platform 16, and the inner hole of the heat insulation ring 1 is aligned with the mounting hole;

[0071] The outer diameter of the heat transfer plate 2 is matched with the size of the inner hole of the heat insulation ring 1, and the heat transfer plate 2 is fixedly installed in the inner hole of the heat insulation ring 1;

[0072] The lower open end of the bearing cylinder 5 is fixedly connected with the upper end surface of the heat transfer plate 2, two through holes are oppositely formed in the left and right ends of the middle section of the bearing cylinder 5, and the inside of the bearing cylinder 5 is filled with accumulated dust;

[0073] The heating assembly comprises a heating power supply, a temperature controller and a heating resistance wire 6, the heating resistance wire 6 is arranged on the lower end surface of the heat transfer plate 2 in a full coverage manner, and is connected with the heating power supply through the temperature controller;

[0074] Two vertical supports 10 are oppositely distributed on the left and right sides of the rack 15, and the lower ends are fixedly connected with the upper end surface of the bottom fixed table 9;

[0075] The pull wire 17 is transversely threaded in two through holes on the bearing cylinder 5, and the two ends are respectively connected with the upper parts of the two vertical supports 10;

[0076] A plurality of first thermocouples 3 are sequentially and spacedly distributed in the interior of the bearing cylinder 5 along the left-right direction, and are installed on the pull wire 17, wherein the two first thermocouples 3 at both ends of the left-right direction are respectively connected with the left side wall and the right side wall of the bearing cylinder 5;

[0077] A plurality of second thermocouples 4 are correspondingly arranged below the plurality of first thermocouples 3, and are attachedly installed on the upper end surface of the heat transfer plate 2;

[0078] The temperature measuring device 8 is arranged on the periphery of the rack 15, for real-time acquisition of the temperature signal in the environment;

[0079] The thermal image acquisition device 7 is arranged above the bearing cylinder 5, and the acquisition surface is parallel to the upper surface of the accumulated dust to be measured, for generating a temperature image by detecting the infrared radiation of the accumulated dust;

[0080] The data processing terminal is connected with the plurality of first thermocouples 3, the plurality of second thermocouples 4, the temperature controller, the temperature measuring device 8 and the thermal image acquisition device 7.

[0081] In order to make the vertical support have elastic supporting ability, and at the same time, to facilitate the adjustment of the supporting height, the vertical support 10 comprises a lower support column 11, a middle section connecting spring 12, an upper support column 13, a height adjusting sleeve 18 and a connecting ear plate 14, the lower end of the lower support column 11 is fixedly connected with the upper end of the bottom fixed table 9, the lower end of the middle section connecting spring 12 is fixedly connected with the upper end of the lower support column 11, the outer thread structure is arranged on the column body of the upper support column 13, and the lower end is fixedly connected with the upper end of the middle section connecting spring 12, the inner diameter of the height adjusting sleeve 18 is matched with the outer diameter of the upper support column 13, and the inner thread structure is arranged in the inside corresponding to the outer thread structure, and is sleeved on the outside of the upper support column 13 through thread cooperation; the outer end of the connecting ear plate 14 is fixedly connected with one side of the upper part of the height adjusting sleeve 18, a wire hole is formed in the inner end, and the pull wire 17 is connected through the wire hole. In order to facilitate manual adjustment of the height of the height adjusting sleeve 18, an adjusting handle can also be fixedly connected with the upper end of the height adjusting sleeve 18.

[0082] In order to ensure the accuracy of the measurement, and at the same time, to ensure the high efficiency of heat transfer, the materials of the bearing cylinder 5 and the heat transfer plate 2 are the same, which are made of metal heat transfer material.

[0083] As a preferred, the data processing terminal is an industrial computer.

[0084] In the application, a mounting hole is formed in the center of the support platform, and the heat transfer plate is fixedly installed in the area where the mounting hole is located by using the heat insulation ring. On this basis, the heating resistance wire is laid on the lower surface of the heat transfer plate. In this way, only the heat transfer plate is efficiently heated during heating, ensuring the efficiency of heating, and ensuring that the heat on the heat transfer plate cannot be transmitted to the surrounding objects, ensuring the stability of the heat on the heat transfer plate and the bearing cylinder, which is conducive to ensuring the accuracy of the test data, and further helps to obtain an accurate heat conduction-heat convection model. The heating resistance wire is connected to the heating power supply through the temperature controller, which can facilitate the use of the temperature controller to control the on-off operation of the heating resistance wire, and the temperature controller can be used to control the heating temperature range of the heating resistance wire. Two through holes are formed on the left and right opposite sides of the middle section of the bearing cylinder, and two vertical supports are installed on the left and right sides of the rack. After the pull wire passes through the two through holes and is connected to the two vertical supports, the pull wire can be stably supported in the middle section of the bearing cylinder. Therefore, the pull wire can be used to provide an installation basis for the plurality of first thermocouples. In this way, after the inside of the bearing cylinder is filled with dust, the plurality of first thermocouples can be used to effectively monitor the temperature at different positions inside the accumulated dust. In addition, the two first thermocouples located at the two ends in the left-right direction are connected to the left and right side walls of the bearing cylinder, respectively, which can ensure that the two first thermocouples can effectively monitor the temperature of the side edges of the accumulated dust. A plurality of second thermocouples are installed on the heat transfer plate in the internal area of the bearing cylinder corresponding to the plurality of first thermocouples. After the inside of the bearing cylinder is filled with dust, the plurality of second thermocouples can be used to effectively monitor the temperature of the lower surface of the accumulated dust. By arranging the temperature acquisition device on the periphery of the rack, the temperature data in the environment can be monitored in real time. By arranging the thermal image acquisition device above the bearing cylinder, the thermal image of the upper surface of the accumulated dust can be acquired in real time, which is conducive to obtaining the temperature data of the upper surface of the accumulated dust. By cooperating the first thermocouple, the second thermocouple, the temperature acquisition device and the thermal image acquisition device, and combining the temperature conduction theory, the temperature conduction test can be completed, and a certain heat conduction-heat convection model can be obtained, which provides reliable technical support for reliable monitoring of the internal temperature of any accumulated dust and positioning of the heat source position.

[0085] The system has simple structure and low manufacturing cost, which can help to reveal the temperature transmission rule inside the accumulated dust, and can help to determine the temperature of each part of the accumulated dust and the position of the internal heat source, thereby effectively reducing the probability of dust explosion accidents and greatly improving the safety factor of production operation.

[0086] The application further provides a method for measuring internal temperature and heat source position of accumulated dust, which adopts a measuring and calculating system for measuring internal temperature and heat source position of accumulated dust, and comprises the following steps:

[0087] Step one: constructing a theoretical equation of heat conduction-heat convection model;

[0088] S11: based on Fourier heat conduction law and energy conservation law, a heat conduction model of internal temperature of accumulated dust is established according to formula (1);

[0089]

[0090] In the formula, T is temperature, t is time, alpha is heat diffusion coefficient, k is thermal conductivity, c is specific heat capacity, rho is density, and g(x, y, z, t) is heat generation rate of internal heat source per unit volume;

[0091] Since the given is the dust accumulation condition of a certain substance, the calculation of thermal conductivity k is relatively complex. For example, when the dust to be measured (such as silicon dioxide dust) is given, the equivalent thermal conductivity of the dust accumulation is the result of the joint action of the dust particles and the air gap, which can be simply estimated as: Wherein, k air is the thermal conductivity of air, about 0.026; is the thermal conductivity of silicon dioxide (amorphous silicon dioxide is about 1.4), and phi is the bulk density of dust (i.e. the proportion of dust volume to total volume);

[0092] S12: constructing a heat convection model of dust surface and air;

[0093] S12-1: the upper surface of the accumulated dust is in contact with air, which will produce convective heat transfer. For the upper surface of the accumulated dust, the convective heat transfer boundary condition is established according to formula (2);

[0094]

[0095] In the formula, is the derivative of temperature in the boundary normal direction, h is the convective heat transfer coefficient, and T air is the air temperature;

[0096] In particular, when calculating the heat conduction of dust and the convective heat transfer of its upper surface with air, the Biot number Bi can be calculated to simplify the calculation, wherein, V is the volume of the accumulated dust, A is the surface area of the accumulated dust in contact with air, if Bi < 0.1, it indicates that the internal thermal conductivity of the solid is extremely small, and the heat transfer process inside the solid does not need to be considered, only the convective heat transfer of the solid with air needs to be considered, if Bi > > 0.1, it indicates that the internal thermal resistance of the object is comparable to or greater than the external thermal resistance, the internal temperature gradient cannot be ignored, and the internal heat conduction of the dust and the convective heat transfer of its surface with air need to be considered.

[0097] S12-2: For the lower surface and the side surface of the accumulated dust, since the lower surface and the side surface of the accumulated dust are in good contact with the bearing cylinder 5, the thermal resistance can be ignored, so the temperature of the lower surface and the side surface of the accumulated dust is the same as that of the bearing cylinder 5;

[0098] Step two: using finite difference method to determine the parameters in the heat conduction-heat convection model;

[0099] S21: discretize the accumulated dust in the bearing cylinder 5 into a three-dimensional grid, each grid point corresponds to a temperature value. The grid should be fine enough to ensure calculation accuracy. Among them, in the radial direction r, from the center of the ring r = 0 to the edge of the ring r = R, the step is Δr; in the angle direction θ, from 0 to 2π, the step is Δθ; in the axial direction z, from the bottom of the dust z = 0 to the top of the dust z = H, the step is Δz;

[0100] S22: discretization of the heat conduction model; based on the heat conduction equation in cylindrical coordinates, the formula (1) is discretized to obtain the discretization equation of the heat conduction model, as shown in formula (3);

[0101]

[0102] In the formula, represents the temperature of the grid point (r i ,θ j ,z k ) of the n-th time step; Δt is the time step; Δr, Δθ, Δz are the grid steps in the radial, angular and axial directions respectively;

[0103] S23: discretization of the heat convection model, to obtain the discretization equation of the heat convection model;

[0104] S23-1: for the upper surface of the accumulated dust, the formula (2) is discretized to obtain the discretization equation of the upper boundary heat convection model, as shown in formula (4);

[0105]

[0106] In the formula, N Z is the grid index of the upper surface of the dust;

[0107] S23-2: For the lower surface and side surface of the accumulated dust, the discretization equations of the lower boundary and side surface heat convection model are obtained according to formula (5) and formula (6) respectively;

[0108]

[0109] wherein, T plate is the temperature of the bearing cylinder 5, N r is the radial grid index of the edge of the bearing cylinder 5;

[0110] S24: A standard temperature hot plate experiment of the accumulated dust is carried out, and the dust surface temperature data and the temperature data of several monitoring points inside the dust are collected;

[0111] S24-1: The bearing cylinder 5 is filled with the dust to be tested, and the thickness of the dust layer in the bearing cylinder 5 is ensured to be uniform, forming the accumulated dust to be tested;

[0112] S24-2: The temperature controller is started to work by the data processing terminal, so that the heating power supply supplies power to the heating resistance wire 6, and the temperature controller controls the heating temperature of the heating resistance wire 6, so that the temperature of the heat transfer plate 2 is constant in the preset temperature range;

[0113] The first temperature signals in the dust layer are collected by the multiple first thermocouples 3 located in the middle section of the bearing cylinder 5 in real time, and are sent to the data processing terminal. The second temperature signals on the surface of the heat transfer plate 2 are collected by the multiple second thermocouples 4 located at the bottom of the bearing cylinder 5 in real time, and are sent to the data processing terminal. The environmental temperature signals are collected by the temperature measuring device 8 in real time, and are sent to the data processing terminal. The data processing terminal obtains the first temperature data, the second temperature data and the environmental temperature data according to the first temperature signals and the second temperature signals respectively;

[0114] At the same time, the infrared radiation of the accumulated dust is detected by the thermal image acquisition device 7 in real time, and a temperature image is generated. The temperature image is sent to the data processing terminal, and the data processing terminal obtains the upper surface temperature data of the dust according to the temperature image;

[0115] S24-3: The data processing terminal divides the multiple first temperature data and the multiple second temperature data according to the position information of the multiple first thermocouples 3 and the position information of the multiple second thermocouples 4, respectively, to obtain the internal temperature data, the side surface temperature data and the lower surface temperature data of the accumulated dust;

[0116] S25: a temperature conduction theory numerical calculation is performed; the obtained internal temperature data is input into the discretization equation of the heat conduction model, the obtained upper surface temperature data, side surface temperature data and lower surface temperature data are input into the discretization equation of the heat convection model as boundary conditions, the thermal conductivity k, the convection heat transfer coefficient h and the thermal diffusivity a of the dust to be measured are determined by calculation, and then the discretization equation of the heat conduction model and the discretization equation of the heat convection model of the dust to be measured are obtained;

[0117] Step three: the internal temperature of the arbitrary accumulated dust is calculated, and the position of the internal heat source is determined;

[0118] S31: a plurality of temperature sensors are buried at key points in the arbitrary accumulated dust;

[0119] S32: a laser scanner is used to scan the arbitrary accumulated dust, three-dimensional surface data of the arbitrary accumulated dust are obtained, and the three-dimensional surface data are sent to a data processing terminal; the data processing terminal generates a three-dimensional geometric model of the arbitrary accumulated dust based on the three-dimensional surface data, discretizes the three-dimensional form of the arbitrary accumulated dust into a finite element network or a finite difference network, obtains a three-dimensional grid of the arbitrary accumulated dust, and determines the coordinates (i, j, k) of each point;

[0120] S33: an infrared thermal imager is used to shoot the temperature distribution of the surface of the arbitrary accumulated dust, and the temperature data of the surface of the arbitrary accumulated dust are sent to a data processing terminal; a temperature sensor is used to collect key point temperature signals in real time and send them to the data processing terminal, and the data processing terminal obtains key point temperature data according to the key point temperature signals;

[0121] S34: the grid point temperature of the outer surface in the three-dimensional grid is fixed as a known value T boundary ;

[0122] S35: the key point temperature data are brought into the discretization equation of the heat conduction model, and a Laplace equation is established, as shown in formula (7);

[0123]

[0124] S36: formula (7) is solved to obtain the temperature at each place in the arbitrary accumulated dust, and the position of the internal heat source in the arbitrary accumulated dust is calculated by reverse fitting, and a three-dimensional temperature field of the accumulated dust is established based on the temperature data at each place in the interior, the position information of the internal heat source, and the three-dimensional temperature field is output to a visualization terminal, and the temperature data at each place in the interior, the internal heat position information and the three-dimensional temperature field are displayed in real time through the visualization terminal.

[0125] As a preferred, in S12 of step one, the discretization network is hexahedron or tetrahedron.

[0126] As a preferred, in S36 of step three, the calculation of the temperature of the internal arbitrary point is carried out by using a thermodynamic iteration method or an efficient algorithm. As a preferred, the efficient algorithm uses fast Fourier transform (FFT) or diagonalization algorithm.

[0127] As a preferred, in S36 of step three, the visualization terminal displays in real time by means of thermal imaging map or three-dimensional temperature cloud chart.

[0128] The application provides a real-time calculation method for three-dimensional temperature field of accumulated dust based on experimental data and heat conduction-heat convection model. First, the theoretical equation of the heat conduction-heat convection model is constructed. Then, the heat conductivity coefficient k, the heat convection coefficient h and the thermal diffusion coefficient a of the current dust to be measured are determined by the finite difference method combined with the standard temperature hot plate experiment. Since the heat conductivity coefficient k, the heat convection coefficient h and the thermal diffusion coefficient a are related to the material itself, the composition, structure, density, temperature and humidity of different materials will affect the specific values of the above coefficients. Therefore, before monitoring the temperature of any accumulated dust, the heat conductivity coefficient k, the heat convection coefficient h and the thermal diffusion coefficient a of the current dust to be measured are determined by the standard temperature hot plate experiment. In this way, the discretization equation of the heat conduction model and the discretization equation of the heat convection model suitable for the current dust to be measured can be obtained, ensuring that the temperature of any accumulated dust can be monitored more accurately and efficiently. Then, based on the key point temperature data obtained by the temperature sensor buried in the key points of any accumulated dust and the temperature distribution of the surface of any accumulated dust obtained by the infrared thermal imager, the Laplace equation can be constructed combined with the discretization equation of the heat conduction model. By solving the Laplace equation, the temperature distribution of any point in any accumulated dust can be derived. In this way, the temperature data of each place in any accumulated dust can be calculated efficiently and accurately. At the same time, the position of the heat source in any accumulated dust can be calculated by reverse fitting, and the three-dimensional temperature field of the accumulated dust can be established based on the temperature data of each place in the internal and the position information of the heat source in the internal. Thus, the scientific monitoring of the temperature data of any accumulated dust can be realized, which can effectively reduce the probability of dust explosion accidents and greatly improve the safety factor of production operation.

Claims

1. A method for measuring internal temperature and heat source location of accumulated dust using a measurement system for measuring internal temperature and heat source location of accumulated dust, characterized by: The measurement system comprises a bottom fixed table, a rack, a heat insulation ring, a heat transfer plate, a bearing cylinder, a heating assembly, vertical supports, a pull wire, a first thermocouple, a second thermocouple, a temperature measuring device, a thermal image acquisition device and a data processing terminal; the lower end of the rack is fixedly installed on the central area of the upper end of the bottom fixed table, the upper end of the rack has a horizontal support platform, and a mounting hole is formed in the central area of the support platform; the hole diameter of the inner hole of the heat insulation ring is matched with the outer diameter of the mounting hole, the heat insulation ring is fixedly installed on the support platform, and the inner hole of the heat insulation ring is aligned with the mounting hole; the outer diameter of the heat transfer plate is matched with the size of the inner hole of the heat insulation ring, and the heat transfer plate is fixedly installed in the inner hole of the heat insulation ring; the lower opening end of the bearing cylinder is fixedly connected with the upper end surface of the heat transfer plate, two through holes are oppositely formed in the left and right ends of the middle section of the bearing cylinder, and the inside of the bearing cylinder is filled with accumulated dust; the heating assembly comprises a heating power supply, a temperature controller and a heating resistance wire, the heating resistance wire is arranged on the lower end surface of the heat transfer plate in a distributed manner, and is connected with the heating power supply through the temperature controller; two vertical supports are oppositely distributed on the left and right sides of the rack, and the lower ends of the vertical supports are fixedly connected with the upper end surface of the bottom fixed table; the pull wire is transversely arranged in the two through holes on the bearing cylinder, and the two ends of the pull wire are respectively connected with the upper parts of the two vertical supports; a plurality of first thermocouples are sequentially and spacedly arranged in the left and right directions in the inside of the bearing cylinder and are installed on the pull wire, wherein the two first thermocouples located at the two ends in the left and right directions are respectively connected with the left side wall and the right side wall of the bearing cylinder; a plurality of second thermocouples are correspondingly arranged below the plurality of first thermocouples and are attached to the upper end surface of the heat transfer plate; the temperature measuring device is arranged on the periphery of the rack and is used for collecting temperature signals in the environment in real time; the thermal image acquisition device is arranged above the bearing cylinder, the collection surface of the thermal image acquisition device is parallel to the upper surface of the accumulated dust to be measured, and the thermal image acquisition device is used for generating a temperature image by detecting infrared radiation of the accumulated dust; and the data processing terminal is connected with the plurality of first thermocouples, the plurality of second thermocouples, the temperature controller, the temperature measuring device and the thermal image acquisition device. The method comprises the following steps: Step one: constructing a theoretical equation of the heat conduction-heat convection model; Step two: determining parameters in the heat conduction-heat convection model by using the finite difference method; Step three: calculating the internal temperature of the arbitrary accumulated dust and determining the position of the internal heat source; S31: burying a plurality of temperature sensors at key points in the inside of the arbitrary accumulated dust; S32: scanning the arbitrary accumulated dust by using a laser scanner to obtain three-dimensional surface data of the arbitrary accumulated dust, and sending the three-dimensional surface data to a data processing terminal; the data processing terminal generates a three-dimensional geometric model of the arbitrary accumulated dust based on the three-dimensional surface data, discretizes the three-dimensional form of the arbitrary accumulated dust into a finite element network or a finite difference network to obtain a three-dimensional grid of the arbitrary accumulated dust, and determines the coordinates of each point ; S33: using an infrared thermal imager to shoot the temperature distribution on the surface of the arbitrary accumulated dust, sending the temperature data on the surface of the arbitrary accumulated dust to the data processing terminal, collecting key point temperature signals in real time by using the temperature sensors and sending the key point temperature signals to the data processing terminal, and obtaining key point temperature data by the data processing terminal according to the key point temperature signals; S34: fixing the temperature of the grid points of the outer surface in the three-dimensional grid as known values according to the temperature data of any accumulated dust surface ; S35: The key point temperature data is brought into the discretization equation of the general heat conduction model to establish the Laplace equation, as follows ; S36: solve the formula in S35, get the temperature of each place inside the arbitrary accumulated dust, and inversely fit to calculate the heat source position inside the arbitrary accumulated dust, and based on the temperature data of each place inside, the heat source position information inside, establish the three-dimensional temperature field of the accumulated dust, then output the temperature data of each place inside, the heat source position information inside and the three-dimensional temperature field to the visualization terminal, and through the visualization terminal, real-time display the temperature data of each place inside, the heat position information inside and the three-dimensional temperature field.

2. A method for determining the internal temperature of a build-up dust and the location of a heat source according to claim 1, characterized in that, The vertical support includes a lower support column, a middle section connecting spring, an upper support column, a height adjusting sleeve and a connecting ear plate, the lower end of the lower support column is fixedly connected with the upper end of the bottom fixed table, the lower end of the middle section connecting spring is fixedly connected with the upper end of the lower support column, the outer thread structure is arranged on the column body of the upper support column, and the lower end of the upper support column is fixedly connected with the upper end of the middle section connecting spring, the inner diameter of the height adjusting sleeve is matched with the outer diameter of the upper support column, an inner thread structure is arranged at the position corresponding to the outer thread structure in the height adjusting sleeve, and the height adjusting sleeve is sleeved on the outside of the upper support column through thread cooperation, and the outer end of the connecting ear plate is fixedly connected with one side of the upper part of the height adjusting sleeve, a wire hole is formed in the inner end of the connecting ear plate, and the connecting ear plate is connected with the pull wire through the wire hole.

3. A method for determining the internal temperature of a build-up dust and the location of a heat source according to claim 1 or 2, characterized in that, The material of the bearing cylinder and the heat transfer plate is the same, and the bearing cylinder and the heat transfer plate are made of metal heat transfer material.

4. A method for determining the internal temperature of a build-up dust and the location of a heat source according to claim 3, characterized in that, The data processing terminal is an industrial computer.

5. The method for determining the internal temperature of the accumulated dust and the location of the heat source according to claim 3, characterized in that, In step one, the process of constructing the theoretical equation of the heat conduction-heat convection model is as follows: S11: a heat conduction model of the interior of the accumulated dust is established according to formula (1); （1）； wherein T is temperature, t is time, a is the thermal diffusivity, q is the volumetric heat generation rate of the internal heat source; c is the specific heat capacity; p is the density; S12: a heat convection model of the surface of the dust and air is constructed; S12-1: for the upper surface of the accumulated dust, a convection heat transfer boundary condition is established according to formula (2); （2）； wherein is the derivative of the temperature in the direction of the boundary normal, is the thermal conductivity, is the convective heat transfer coefficient, is the air temperature; S12-2: for the lower surface and the side surface of the accumulated dust, the temperature of the lower surface and the side surface is the same as that of the bearing cylinder; In step two, the process of determining the parameters in the heat conduction-heat convection model by using the finite difference method is as follows: S21: Discretize the accumulated dust inside the bearing cylinder into a three-dimensional mesh, wherein, in the radial direction... Direction, from the center of the ring to the edge of the ring Step size is ; in angle and direction Direction, from 0 to Step size is ; in the axial direction Direction, from the bottom of the dust To the top of the dust Step size is ; S22: discretization of the heat conduction model; based on the heat conduction equation in the cylindrical coordinate system, the formula (1) is discretized to obtain the discretization equation of the heat conduction model, as shown in formula (3); （3）； wherein Tn represents the temperature of the nth time step grid point ; is the time step; , , are the radial, angular and axial grid steps, respectively S23: discretization of the heat convection model to obtain the discretization equation of the heat convection model; S23-1: for the upper surface of the accumulated dust, the formula (2) is discretized to obtain the discretization equation of the upper boundary heat convection model, as shown in formula (4); （4）； In the formula, is the grid index of the upper surface of the dust S23-2: for the lower surface and the side surface of the accumulated dust, the discretization equations of the lower boundary and the side surface heat convection model are obtained according to formula (5) and formula (6) respectively; （5）； （6）； wherein is the temperature of the carrier tube, is the radial grid index of the carrier tube edge; S24: standard temperature heat plate experiment of the accumulated dust is carried out, and the dust surface temperature data and the temperature data of several monitoring points inside the dust are collected; S24-1: the inside of the bearing cylinder is paved with the dust to be tested, and the thickness of the dust layer in the bearing cylinder is ensured to be uniform, forming the accumulated dust to be tested; S24-2: the temperature controller is started to work by the data processing terminal, the heating power supply is powered on to the heating resistance wire, and the heating temperature of the heating resistance wire is controlled by the temperature controller, so that the temperature of the heat transfer plate is constant in the preset temperature range; The first temperature signals in the dust layer are collected by a plurality of first thermocouples located in the middle section of the bearing cylinder in real time and sent to a data processing terminal. The second temperature signals on the surface of the heat transfer plate are collected by a plurality of second thermocouples located at the bottom of the bearing cylinder in real time and sent to the data processing terminal. The ambient temperature signals are collected by a temperature measuring device in real time and sent to the data processing terminal. The data processing terminal obtains first temperature data, second temperature data and ambient temperature data according to the first temperature signals and the second temperature signals respectively. Meanwhile, the infrared radiation of the accumulated dust is detected by a thermal imaging acquisition device in real time, and a temperature image is generated. The temperature image is sent to the data processing terminal, and the data processing terminal obtains the upper surface temperature data of the dust according to the temperature image. S24-3: The data processing terminal divides the obtained plurality of first temperature data and plurality of second temperature data according to the position information of the plurality of first thermocouples and the position information of the plurality of second thermocouples, respectively obtains the internal temperature data, the side temperature data and the lower surface temperature data of the accumulated dust. S25: a temperature conduction theory numerical calculation is performed; the obtained internal temperature data is input into the discretization equation of the heat conduction model, the obtained upper surface temperature data, side surface temperature data and lower surface temperature data are input into the discretization equation of the heat convection model as boundary conditions, and the heat conductivity coefficient of the dust to be measured is determined by calculation , the convection heat transfer coefficient and the thermal diffusivity , and the discretization equation of the heat conduction model and the discretization equation of the heat convection model of the dust to be measured are obtained.

6. A method for determining the internal temperature of a build-up dust and the location of a heat source according to claim 5, characterized in that, In step one S12, the discretized network is a hexahedron or a tetrahedron.

7. A method for determining the internal temperature of a build-up dust and the location of a heat source according to claim 6, characterized in that, In step three S36, a thermodynamic iteration method or a high-efficiency algorithm is used to calculate the temperature of any point inside.

8. A method for determining the internal temperature of a build-up dust and the location of a heat source according to claim 7, characterized in that, In step three S36, the visualization terminal displays in real time through a thermal imaging image or a three-dimensional temperature cloud chart.

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