JP2018128399A - Solid fuel firing estimation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid fuel firing estimation method for estimating a solid fuel flammability inside a pulverizer or the like by estimating an exothermal event of the deposited powder of a solid fuel.SOLUTION: An estimation method of flammability of deposited powder of a solid fuel predicts a heat generation of the deposited powder by differentiating and numerically solving a heat conduction equation (1) of the following non-steady three-dimensional orthogonal coordinate system (x, y, z) representing a heat generation state of the deposited powder of the solid fuel using a heat generation rate obtained from an analysis of a temperature rise rate of a spontaneous ignition estimation test relevant to the solid fuel and a thermophysical property value of the solid fuel. [Numeral 1](In this case, λ is thermal conductivity [J/m/s/K], Cp is specific heat [j/Kg/K], ρ is bulk density [kg/m], T is absolute temperature, and Q is heat generation [W/m] per unit volume)SELECTED DRAWING: None

Description

  The present invention relates to a solid fuel ignitability evaluation method for evaluating the ignitability of a solid fuel such as coal in a pulverizer or the like.

  In Japan's pulverized coal-fired power plants, the use of low-grade coal is expanding from the viewpoint of cost reduction and ensuring energy security. Among these low-grade coals, sub-bituminous coal and lignite coal are exothermic. The coal is considered to be high.

  Here, in the power plant, in order to obtain high combustion efficiency, the coal is finely pulverized with a pulverizer, and the moisture in the coal is dried using heated air, but when pulverizing the low-grade coal, There is concern about the ignition of coal inside the grinder.

  It is thought that the main cause of the ignition of coal in the pulverizer is that the coal (pulverized coal) locally accumulated in the pulverizer accumulates heat and ignites. When coal fires in the crusher, unplanned plant shutdowns can occur for long periods of time due to equipment inspection and recovery.

  In order to prevent the ignition of coal in the pulverizer, the risk of ignition is predicted in advance, and coal that is judged to be highly ignited can be changed in the operation method of the pulverizer, It is important to operate in a manner that reduces the risk of ignition by mixing coal with low-risk coal.

  However, the detailed conditions for the ignition of coal in the pulverizer, such as the relationship between the amount of deposits that lead to the ignition of coal and the ambient temperature, have not been clarified, and the method for evaluating the ignition of coal in the pulverizer has not been established. is the current situation.

  By the way, there have been many basic and practical studies on the heat generation of coal, and there are also many evaluation methods.

  For example, as a spontaneous ignition evaluation method, there is a spontaneous ignition evaluation test device (Spontaneous Ignition Tester-2, hereinafter referred to as SIT-2) manufactured by Shimadzu Corporation. This equipment is a test method in which a reactor filled with a sample is installed in a thermostat, air is circulated, and the temperature of the thermostat is controlled by the thermostat so as to follow the temperature of the sample. (See Patent Document 1).

  This test method is often used in Japan to evaluate the ignitability of coal, but the result is that the accumulated powder lump is kept in an adiabatic state and is different from the state of coal in the crusher. It is difficult to apply to the evaluation of exothermic phenomenon as it is.

  As another spontaneous ignition evaluation method, there is a self-heating evaluation test apparatus (Wire Base method, hereinafter referred to as WB method). In this test method, a cubic container with a side of 25 mm or 100 mm filled with a sample is suspended in a constant temperature bath, the temperature in the bath is maintained at a predetermined temperature, and the presence or absence of ignition within a predetermined time is checked. This is a method of evaluating and determining the exothermic property of the sample based on the result. In addition, a simple calculation model for the WB method has been studied. By solving the heat conduction equation of the one-dimensional orthogonal coordinate system, the temperature rise of the deposit can be obtained by calculation (see Non-Patent Document 1).

  In this method, the influence of heat radiation from the deposit is taken into consideration, but the temperature range to be evaluated is different from the atmosphere in the pulverizer. In addition, it is considered that the calculation in the one-dimensional orthogonal coordinate system has a problem in accuracy, and it is difficult to apply the evaluation result as it is to the evaluation of the exothermic phenomenon of coal in the pulverizer.

A method for preventing ignition in a pulverizer has been proposed in which the concentration of CO and CO _{2 in} the gas at the outlet of the pulverizer is measured, and when there is a sign of ignition, the supply amount of coal, which is considered to be low in heat generation, is increased. (See Patent Document 2). However, in this method, it is necessary to perform continuous analysis of the atmospheric gas in the pulverizer, and there is a problem that capital investment is required when it is introduced into existing equipment.

  Also, a coal pulverization method has been proposed in which the concentration of CO in the gas at the outlet of the pulverizer is measured and when there is a sign of ignition, the amount of hot air is reduced and the amount of coal supplied is reduced (Patent Literature). 3). However, in order to realize this method, it is necessary to perform continuous analysis of the atmospheric gas in the pulverizer, and there is a problem that capital investment is required when introducing the existing equipment.

Japanese Patent No. 3511787 Japanese Patent No. 5385853 Japanese Patent No. 5710149

Yoshitada Shimizu et al., Thermal Storage Fire Risk and Prediction of Waste (1), Kanagawa Industrial Technology Center Research Report No. 16, 2010

  An object of the present invention is to provide a solid fuel ignitability evaluation method that evaluates the exothermic phenomenon of solid fuel such as coal in a pulverizer and the like and evaluates the solid fuel ignitability in the pulverizer and the like in view of the above-described conventional technology. And

  An aspect of the present invention that achieves the above object is a method for evaluating the ignitability of a deposited powder lump of solid fuel, the heat generation rate obtained from the analysis of the temperature rise rate of the spontaneous ignition evaluation test for the solid fuel, Using the thermophysical property value of the solid fuel, the difference in the heat conduction equation (1) in the following unsteady three-dimensional orthogonal coordinate system (x, y, z) representing the heat generation state of the solid powder deposited powder mass The solid fuel ignitability evaluation method is characterized by predicting heat generation of the deposited powder lump by numerically solving and numerically solving.

(Where λ is the thermal conductivity [J / m / s / K], Cp is the specific heat [J / kg / K], ρ is the bulk density [kg / m ³ ], T is the absolute temperature [K], Q Is the calorific value [W / m ³ ] per unit volume)

  In such an embodiment, the heat generation rate obtained from the analysis of the temperature rise rate in the spontaneous ignition evaluation test for the solid fuel and the thermal property value of the solid fuel are used to represent the heat generation state of the solid powder deposited powder mass. The heat generation equation of the three-dimensional orthogonal coordinate system (x, y, z) can be differentiated and numerically solved to easily predict the heat generation of the deposited powder mass.

  The heat conduction equation (1) is differentiated by a difference method to obtain a difference equation, and each thermal physical property data (λ, Cp, ρ), heat generation rate data, initial temperature condition, boundary for the deposited powder mass Conditions are given, and the temperature distribution of the deposited powder mass after an arbitrary time is obtained by repeatedly calculating the temperature change for each element.

  Here, the difference (difference method) is to replace differentiation with division of a finite difference in time or space, and by performing difference approximation, the differential equation can be solved by four arithmetic operations. The difference method includes an explicit solution method and an implicit solution method. In the following embodiments, a case where an explicit solution method is used will be described.

  According to the explicit method, the following differential equation (2) is obtained. By giving each thermophysical property data (λ, Cp, ρ), heat generation rate data, temperature initial condition, boundary condition for the deposited powder mass, and repeatedly calculating the temperature change for each element, any time later The temperature distribution of the deposited powder mass can be obtained.

(Here, the x direction is divided by Δx, the y direction is divided by Δy, the z direction is divided by Δz, and the lattice point numbers are represented by i, j, and k, respectively. (The number is represented by p, and α = λ / ρCp.)

  The heat generation rate data is obtained by analyzing the temperature rise rate using a spontaneous ignition evaluation test method for a solid sample such as a spontaneous ignition evaluation tester (Spontaneous Ignition Tester-2).

  SIT-2 is a spontaneous ignition evaluation test method classified as an adiabatic method. The adiabatic method is a method in which a container filled with a sample is placed in a thermostatic chamber that is insulated, the temperature of the sample is monitored in an air or oxygen gas atmosphere, and the temperature of the thermostatic chamber follows the temperature of the sample. In addition to SIT-2, ARC (Accelerating Rate Calorimeter) can be cited as a test method using the adiabatic method.

  Any method may be adopted as long as the exothermic rate data is a spontaneous ignition evaluation test method for a solid sample for analyzing the rate of temperature increase. There is.

  The calorimetric method is to change the temperature of the sample to be measured and the reference material according to a certain program, and heat the reference material side or the measurement sample side so that the temperature difference (ΔT) between the two becomes zero. This is a method for measuring the amount of heat that enters and exits the sample material. Examples of the test method based on calorimetry include DSC (Differential Scanning Calorimeter) and C80.

  Isothermal calorimetry is a method of measuring minute heat by filling a sample inside a thermostatic oil layer with precisely controlled temperature and measuring the amount of heat generated by the heat generated outside with a thermal element. It is a method to do. An example of a test method based on the isothermal calorimetry is TAM (Thermal Activity Monitor).

  According to the present invention, there is provided a method for evaluating the solid fuel deposited powder lump ignitability, which can evaluate the exothermic phenomenon of the solid fuel accumulated powder lump and easily evaluate the solid fuel ignitability in a pulverizer or the like. Can be provided.

It is a figure which shows schematic structure of SIT-2 used by embodiment. It is a figure which shows the test result in SIT-2. It is a figure which shows the Arrhenius plot of A charcoal. It is a figure which shows the temperature history of the center of a deposit powder lump. It is a figure which shows the relationship between the magnitude | size of a deposit powder lump, and an ignition limit atmospheric temperature. It is a figure which shows the relationship between the magnitude | size of the deposit powder lump of each coal, and an ignition limit atmospheric temperature.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  In the present invention, in order to evaluate the ignitability of a deposited powder lump of solid fuel such as coal, first, the following unsteady three-dimensional orthogonal coordinate system representing the heat generation state of the deposited powder lump represented by coal as a solid fuel. The heat conduction equation (1) of (x, y, z) was used.

(Where λ is the thermal conductivity [J / m / s / K], Cp is the specific heat [J / kg / K], ρ is the bulk density [kg / m ³ ], T is the absolute temperature [K], Q Is the calorific value [W / m ³ ] per unit volume)

  In order to evaluate the exothermic heat of pulverized coal deposits, it is necessary to consider the effects of exothermic reaction of coal, heat transfer, gas flow in the sediment, diffusion, evaporation of moisture in the coal, etc. In 1), the temperature rise inside the coal pile is determined by the heat generation due to the oxidation of the coal and the heat release due to the heat transfer.

  The system to be analyzed in the present invention is relatively small, and in the WB method, the influence of gas flow and moisture evaporation is considered to be small, and the oxygen concentration in the deposit is assumed to be 21%, which is the same as air. The heat conduction equation is an unsteady three-dimensional orthogonal coordinate system (x, y, z) in order to solve the internal temperature distribution of the deposited powder mass by the WB method.

  In the present invention, this is differentiated and numerically solved to predict the heat generation of the deposited powder lump.

  Here, assuming that the oxidation heat generation rate can be expressed by an Arrhenius type equation, the calorific value per unit volume is expressed by equation (1-1), so equation (1-2) becomes the following equation.

here,
A: Constant (frequency factor) [J / m ³ / s]
Ea: activation energy [J / mol]
R: Gas constant [8.314 J / K / mol]
T: Coal temperature [K]
It is.

  In order to calculate the heat generation of the deposited powder mass, a method is used in which the partial differential equation is differentiated and numerically solved. In a three-dimensional orthogonal coordinate system, the x direction is divided by Δx, the y direction is divided by Δy, and the z direction is divided into elements at equal intervals for each Δz, and the lattice point numbers are represented by i, j, and k, respectively. Time is ticked at every Δt, and the number is expressed by p. When the equation (1) is differentiated by the explicit method, the following difference equation is obtained.

  However,

とした。

It was.

  The shape of the deposited powder mass was a cube to match the conditions with the WB method, and the size of one side was L. In addition, the area to be calculated is a half area of each side of the cube (a cube with one side being L / 2), assuming that the physical properties of the deposited powder lump are uniform and the temperature conditions around the accumulated powder lump are constant. Suppose that each side is divided into n. In this case, the length of each calculation grid is

となる。

It becomes.

  It is assumed that the initial condition of the temperature of the deposited powder mass is equal to the ambient temperature given as the calculation condition.

  As the boundary condition of the wall surface, the temperature of the wall surface is assumed to be equal to the ambient temperature. Further, the boundary condition at the center of the accumulated powder lump in the calculation area is as follows.

  Based on the calculation method, the initial temperature condition, and the boundary condition, the temperature distribution of the deposited powder mass after an arbitrary time can be obtained.

  Hereinafter, the present invention will be described in more detail based on examples. In this case, coal A as sub-bituminous coal and coal B as bituminous coal were used.

Example 1
First, the temperature rise due to the heat generation of the accumulated powder lump was determined for the coal A by the method of the present invention. Table 1 shows the parameters used for the calculation. The bulk density is an actual value when the exothermic property of the deposited powder mass is measured by the WB method. Specific heat was measured by a DSC method (differential scanning calorimeter DSC Q100 manufactured by TA instruments), and thermal conductivity was measured by a hot wire method (rapid thermal conductivity meter QTM500 manufactured by Kyoto Electronics Industry Co., Ltd.). As the apparent activation energy and frequency factor, the SIT-2 analysis results shown below (Table 2) were used.

(Analysis with SIT-2)
A spontaneous ignition evaluation test apparatus (Spontaneous Ignition Tester-2, hereinafter referred to as SIT-2) was used for examining the heat generation rate.

  An outline of the test apparatus is shown in FIG. In such an apparatus, a reactor 32 is provided in an oven 31, a cylindrical test container 33 is disposed inside the reactor 32, and the sample S 1 can be filled inside the test container 33. A gas supply pipe 34 is provided at the lower part of the reactor 32, and is ventilated from an exhaust pipe 35 communicating with the upper side of the test container 33.

  An adiabatic control heater 36 is provided around the reactor 32, and the temperature is adjusted by a temperature controller 37. An amplifier 40 that acquires data from thermocouples 38 and 39 provided in the reactor 32 and the test vessel 33 is connected to the temperature controller 37.

  Further, a heater 41 and a temperature controller 42 are provided in the lower part of the oven 31, and an initial temperature in the oven 31 is set by a temperature sensor 43 and an initial temperature setting device 44 provided in the oven 31. ing. A fan 45 is provided below the heater 41.

  The test conditions are such that the amount of the filled sample in the test vessel 33 is about 800 mg, nitrogen gas is supplied to the reactor 32 at 2.2 ml / min, and when the temperature of the coal sample in the reactor 32 is stabilized, the supply gas is changed from nitrogen to air. The test was terminated when the sample temperature reached 250 ° C.

  When pulverizing coal at a pulverized coal-fired power plant, high-moisture coal has a higher pulverizer inlet temperature and higher pulverizer inlet temperature depending on the moisture content of the coal than bituminous coal with less moisture . However, since the temperature of this dry air decreases immediately after flowing into the pulverizer due to the latent heat of vaporization of the water in the coal, the internal temperature of the pulverizer is the same regardless of the type of coal, and the pulverizer outlet temperature is the same. Knowing asymptotics. Since the crusher outlet temperature is often operated at about 70 ° C. to 80 ° C. in actual machines, the test start temperature in SIT-2 here is 80 ° C., which is the same condition as the crusher internal temperature. As discussed. The test results are shown in FIG.

  Coal A and Coal B generated an exotherm to 250 ° C. within 24 hours.

  Next, the apparent activation energy and frequency factor were obtained as the rate constant of the coal oxidation reaction by the following analysis.

  The temperature rise inside the coal deposit is determined by the heat generated by the oxidation of the coal and the heat released by the heat transfer. At this time, the basic equation of heat transfer in the cylindrical coordinate system is as follows.

here,
ρ: Coal density [kg / m ³ ]
Cp: Specific heat of coal [J / kg / K]
λ: Thermal conductivity [J / m / s / K]
Q: Calorific value per unit volume [W / m ³ ]
It is.

  The first term on the right side represents the heat conduction term in the cylindrical coordinate system, and the second term on the right side represents the heat generation term. Further, assuming that the oxidation heat generation rate can be expressed by an Arrhenius type equation, the heat generation amount per unit volume is expressed as follows.

here,
A: Constant (frequency factor) [J / m ³ / s]
Ea: Activation energy [J / mol]
R: Gas constant [8.314J / K / mol]
T: Coal temperature [K]
It is.

  Therefore, Expression (11) becomes the following Expression (13).

  From the principle of SIT-2 test method, the internal and external temperatures are the same,

である。

It is.

  Air flows inside the coal from the bottom to the top, but there is no temperature difference between the top and bottom, and there is no temperature difference in the θ direction.

となる。そのため、式（１３）は、右辺は発熱項のみの式になり、次式のように表すことができる。

It becomes. Therefore, the expression (13) is an expression having only a heat generation term on the right side, and can be expressed as the following expression.

  Next, using the results shown in FIG. 2, the rate of increase at each temperature was determined, and the logarithm thereof was plotted against the reciprocal of the temperature (Arrhenius plot). The result is shown in FIG.

  As can be seen in FIG. 3, the temperature rise tendency can be evaluated in three stages. At the first oxidation region (region (1)) from 80 ° C. to 120 ° C. and the second oxidation region (region (2)) from 120 ° C. to 200 ° C. The oxygen supply rate is limited (region (3)).

  In the first oxidized region and the second oxidized region, 1 / T is linear with respect to Log (dT / dt). It was considered that the linearity was different and the oxidation reaction was different.

  From this Arrhenius plot, the apparent activation energy and frequency factor of the reaction in each temperature region can be calculated. The results are shown in Table 2.

  It implemented on the calculation conditions of the following Table 3 with respect to the 100-mm-sized cube of the one side of the accumulation powder lump. FIG. 4 shows the calculation result of the time-dependent change of the deposited powder lump center temperature when the ambient temperature is 110 ° C. and 100 ° C., as a dotted line. For comparison, the solid line shows the actual measurement value (experimental value) of the change in sample temperature over time in the case of the atmospheric temperature of 110 ° C. and 100 ° C. in the WB method as a comparative example. The start time (0 minutes) is shown as a stage where the temperature of the center of the deposited powder mass reaches the ambient temperature even in the actual measurement value in the WB method.

  In the calculation results, when the ambient temperature was 110 ° C., the internal temperature increased at an accelerated rate as time passed. On the other hand, under the calculation condition of 100 ° C., the calculation result showed convergence to a constant temperature after 24 hours. Compared with the experimental values, there is a difference in the time taken to raise the temperature to 250 ° C when heat is generated, and there is a difference in the temperature even when the internal temperature converges. It was.

  Next, the relationship between the size of the deposited powder mass and the ignition limit ambient temperature was calculated by the following method. In the calculation results when 24 hours have elapsed under the conditions of each deposited powder lump, when the temperature at the center of the accumulated powder lump generates heat of 60 ° C. or higher than the temperature of the initial condition, it is determined as ignition, and 60 ° C. or higher. It is determined not to ignite when no heat is generated. One side of the deposited powder mass was changed from 15 mm to 200 mm, and the lower limit atmospheric temperature at which the ignition was judged under the conditions of each deposition amount, that is, the ignition limit ambient temperature was obtained.

  FIG. 5 shows the calculation result of the relationship between the size of the deposited powder lump in the coal A and the ignition limit ambient temperature with a solid line. In addition, the same figure also shows the actual value (experimental value) of the presence or absence of ignition in the WB method of the comparative example (◯: ignition, x: not ignited). In both the calculation result and the actual value in the WB method, the ignition limit ambient temperature became lower as the accumulated powder lump became larger. Therefore, in order to prevent ignition in the pulverizer, it is considered important to reduce the amount of pulverized coal deposited in the pulverizer. In addition, as in the experiment by the WB method, it was confirmed in numerical analysis that the time required for the temperature rise to 250 ° C. increases as the size of the deposited powder lump increases. Furthermore, from the calculation results, it was predicted that if one side of the accumulated powder lump exceeds a certain size, it could be ignited even at an atmospheric temperature of 80 ° C., which is equivalent to the internal temperature of the pulverizer.

  In comparison of the ignition limit atmosphere temperature between the experimental value and the calculated value by the WB method, when the size of one side of the cube is 100 mm, the calculated value is about 100 ° C., and the experimental value is between 100 ° C. and 110 ° C. Therefore, the difference between the two results is small. On the other hand, when one side of the cube was 25 mm, the calculated value was about 220 ° C., but the experimental value was between 140 ° C. and 150 ° C., and the difference between the results was large. The difference in the results may be attributed to the fact that the influence of oxygen diffusion and water evaporation is not taken into consideration in Equation (1). To further increase the accuracy of the calculation, these influencing factors will be considered in the future. It is considered necessary.

  Further, for bituminous coal B coal, the relationship between the deposition amount and the ignition limit ambient temperature was obtained by calculation in the same manner as for subbituminous coal A coal. The bulk density (ρ) was calculated from the amount of coal filled in the WB method, and the heat generation rate data (Ea, A ′) used was the value (Table 2) obtained by the analysis of SIT-2 described above. The specific heat (Cp) and the thermal conductivity (λ) were considered to have little difference due to the difference in the coal type, and the same values (Table 1) as those of sub-bituminous coal A were used.

  FIG. 6 shows the relationship between the size of the deposited powder lump of each coal and the ignition limit ambient temperature based on the calculation result. Comparing the calculation results when the size of the deposited powder lump is a cube with a side of 100 mm, the ignition limit atmosphere temperature is lower for sub-bituminous coal A coal. Further, when comparing the size of the deposited powder mass that ignites at an atmospheric temperature of 80 ° C., which is equivalent to the atmospheric temperature in the pulverizer, sub-bituminous coal A coal is smaller. Therefore, sub-bituminous coal A coal is ignited with a smaller deposition amount, and therefore, it is determined that coal has a higher risk of ignition in the pulverizer than bituminous coal B coal.

  When the present invention is applied at a power plant, for example, the following method can be considered. The present invention is applied to coal that is scheduled to be received at a power plant, and it is digitized and ranked according to the risk of ignition of coal in the crusher. Coal that is judged to be highly ignitable will not be accepted by the power plant. Alternatively, coal with high ignitability can be prevented from igniting coal in the pulverizer by operating with coal having low ignitability. Or coal with high ignitability can prevent ignition of coal in a crusher by aiming at operation which lowers a crusher exit temperature. Lowering the pulverizer outlet temperature reduces the drying efficiency of coal compared to normal operation, resulting in lower combustion efficiency in the boiler, but lowering the risk of ignition efficiently. Therefore, the effect is considered to be small.

  That is, by using the present invention, as described above, it is possible to prevent a coal fire disaster in the pulverizer. In addition, since efficient operation of low-grade coal can be achieved, it is possible to contribute to the expansion of the introduction of low-grade coal and the accompanying fuel procurement cost reduction.

  In power plants, solid fuels such as biomass fuels and sludge carbonized fuels may be mixed and used in addition to coal, but the present invention can also be applied to such cases. Further, the present invention can be applied not only to the ignition in the pulverizer described in the embodiment, but also to the prediction of heat generation of the accumulated powder lump of the solid fuel in the coal storage place, the biomass storage place, or the like.

  The present invention can be usefully used, for example, in a power plant such as a pulverized coal thermal power plant, or in a facility that operates various boilers that use raw coal as a raw material to reduce the risk of ignition. Can do.

31 Oven 32 Reactor 33 Test vessel 34 Gas supply pipe 35 Exhaust pipe 36 Heat insulation heater 37 Temperature controller 38, 39 Thermocouple 40 Amplifier 41 Heater 42 Temperature controller 43 Temperature sensor 44 Initial temperature setter 45 Fan S1 Sample

Claims (3)

A method for evaluating the ignitability of a solid powder deposit powder mass,
Using the heat generation rate obtained from the analysis of the rate of temperature rise in the spontaneous ignition evaluation test for the solid fuel and the thermophysical property value of the solid fuel, Solid fuel ignitability characterized by predicting heat generation of the deposited powder mass by differentiating and numerically solving the heat conduction equation (1) of a three-dimensional orthogonal coordinate system (x, y, z) Evaluation method.

(Where λ is the thermal conductivity [J / m / s / K], Cp is the specific heat [J / kg / K], ρ is the bulk density [kg / m ³ ], T is the absolute temperature [K], Q Is the calorific value [W / m ³ ] per unit volume)   The heat conduction equation (1) is differentiated by a difference method to obtain a difference equation, and each thermophysical property data (λ, Cp, ρ), heat generation rate data, initial temperature condition for the deposited powder mass, 2. The solid fuel ignitability evaluation method according to claim 1, wherein a temperature distribution of the deposited powder lump after an arbitrary time is obtained by giving boundary conditions and repeatedly calculating a temperature change for each element. The heat generation rate data is obtained by analyzing a temperature rising rate using a spontaneous ignition evaluation test method of solid fuel represented by a spontaneous ignition evaluation test device (Spontaneous Ignition Tester-2). The solid fuel ignitability evaluation method according to claim 2.

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