Method for measuring and calculating CO gas critical value in goaf of high gas and spontaneous combustion coal seam

Abstract

This invention provides a method for calculating the critical value of CO gas in the goaf of a high-gas, spontaneously combustible coal seam. The method includes step one: conducting a programmed temperature rise experiment on the residual coal in the goaf based on chromatographic analysis of coal seam spontaneous combustion indicator gases and an index optimization method, to obtain the CO gas generation rate v of the residual coal at different oxidation stages. CO Step two involves measuring parameters such as the air supply volume of the working face in the goaf, the air leakage rate of the working face, the working face advance speed, the width of the coal spontaneous combustion heat dissipation zone in the goaf, and the width of the coal spontaneous combustion oxidation zone in the goaf. Step three involves determining the influence coefficients of the working face advance speed, the gas content of residual coal, and the roof pressure of the goaf on the critical CO gas value of the goaf in high-gas, spontaneously combustible coal seams. Based on the CO gas generation rate and the influence coefficients, the critical CO gas value of the goaf in high-gas, spontaneously combustible coal seams is determined. This ensures that the assessment of the spontaneous combustion hazard of coal in the goaf of high-gas, spontaneously combustible coal seams is scientific and reliable.

Description

Technical Field

[0001] This invention relates to the field of mine safety engineering technology, and more specifically, to a method for calculating the critical value of CO gas in the goaf of a high-gas, easily spontaneously combustible coal seam. Background Technology

[0002] Spontaneous combustion of coal in goaf areas is one of the major hazards in mines, causing severe personnel and property losses and seriously affecting safe production. Predicting and forecasting the spontaneous combustion status of coal in goaf areas is fundamental to the efficient prevention and control of such disasters. When mining easily ignited or spontaneously combustible coal seams, spontaneous combustion monitoring is necessary to determine the marker gases and critical values ​​for spontaneous combustion. Therefore, the selection of marker gases and the determination of critical values ​​are crucial aspects of monitoring spontaneous combustion in goaf areas. The rationality of the selected marker gases and the scientific nature of the determined critical values ​​directly affect the efficiency and cost of preventing and controlling spontaneous combustion in goaf areas. If the marker gases and critical values ​​are too sensitive, spontaneous combustion warnings may be too frequent or even false, leading to excessive prevention measures, increased manpower and material resources for mine fire prevention, and even disruption to normal production at the working face. If the determination of marker gases and critical values ​​is too delayed, it may lead to untimely early warning of coal spontaneous combustion, missing the best opportunity for prevention and control, increasing the difficulty and investment in prevention and control, and even causing spontaneous combustion disasters or secondary disasters. Therefore, the scientific determination of marker gases and critical values ​​for spontaneous combustion of coal in goaf areas is crucial for the efficient prevention and control of spontaneous combustion of coal in goaf areas.

[0003] Currently, my country has relevant test standards for determining the marker gases for spontaneous combustion of coal, but there is no specific method for determining the critical values. The determination of critical values ​​mainly refers to the determination of the CO gas critical value, because CO is the most commonly used marker gas among all marker gases and accompanies all stages of coal spontaneous combustion. If CO gas is used to reflect the spontaneous combustion state of coal, it is necessary to determine the CO gas critical value for each stage of coal spontaneous combustion. Other gases, since their occurrence temperature is generally relatively fixed, are usually used as their critical values ​​to reflect the spontaneous combustion state of coal.

[0004] The determination of the CO gas critical value in the goaf of high-gas, spontaneously combustible coal seams differs from that in general goaf areas. Firstly, the spontaneous combustion oxidation rate of residual coal in the goaf is faster, requiring more timely and accurate prediction of the coal's spontaneous combustion oxidation state. Secondly, gas outbursts affect the oxidation of residual coal, thus impacting the CO generation rate. Furthermore, the exothermic oxidation of residual coal in the goaf can easily ignite high-concentration gas, leading to secondary disasters and severely impacting mine safety. Therefore, the determination of the CO gas critical value in the goaf of high-gas, spontaneously combustible coal seams requires greater scientific rigor and precision; however, existing methods for determining the CO gas critical value in such areas are limited. Summary of the Invention

[0005] The main objective of this invention is to provide a method for calculating the critical value of CO gas in high-gas, spontaneously combustible coal seams, thereby addressing the limitations of existing methods for determining the critical value of CO gas in goaf areas of high-gas, spontaneously combustible coal seams.

[0006] To achieve the above objectives, according to one aspect of the present invention, a method for calculating the critical value of CO gas in a goaf of a high-gas, spontaneously combustible coal seam is provided. This method includes the following steps: Step one, conducting a programmed temperature rise experiment on the residual coal in the goaf based on chromatographic analysis of coal seam spontaneous combustion indicator gases and an index optimization method, to obtain the CO gas generation rate v of the residual coal at different oxidation stages. CO Step 2: Measure the air supply volume of the working face in the goaf, the air leakage rate of the working face in the goaf, the advancing speed of the working face, the width of the spontaneous combustion heat dissipation zone of the coal in the goaf, the width of the spontaneous combustion oxidation zone of the coal in the goaf, the periodic pressure step distance of the working face, the burial depth of the working face, the gas content of the coal seam, and the residual gas content of the remaining coal in the goaf. Step 3: Determine the influence coefficients of the advancing speed of the working face, the gas content of the remaining coal, and the roof pressure of the goaf on the critical value of CO gas in the goaf of high-gas, easily spontaneously combustible coal seams. Determine the critical value of CO gas in the goaf of high-gas, easily spontaneously combustible coal seams based on the CO gas generation rate and the influence coefficients.

[0007] Furthermore, the influence coefficient K1 of the working face advance speed on the critical value of CO gas is calculated by the following relationship (1): Where v0 is the working face advancing speed when measuring working face parameters, in m / d; v1 is the working face advancing speed when applying CO gas critical value, in m / d.

[0008] Furthermore, the influence coefficient K2 of the gas content of the aforementioned residual coal on the critical value of CO gas is calculated by the following relationship (2): Where V0 is the gas content of the coal seam, in m³. 3 / t; V1 represents the residual gas content of the coal in the goaf, in m³. 3 / t; V′ is the relative gas emission rate in the mine, in m³. 3 / t.

[0009] Furthermore, the influence coefficient K3 of the roof pressure in the goaf on the critical value of CO gas is calculated by the following relationship (3): Where x is the distance from the working face within the goaf, in meters; k is a coefficient; L is the periodic pressure step distance of the working face, in meters; and H is the burial depth of the residual coal in the goaf, in meters.

[0010] Furthermore, when H ≤ 600, k = 10, and when H > 600, k = 5.

[0011] Furthermore, the aforementioned CO gas critical value It is calculated from the following relation (4): L1 is the width of the spontaneous combustion heat dissipation zone of coal in the goaf, in meters; L2 is the width of the spontaneous combustion oxidation zone of coal in the goaf, in meters; L′ is the length of the working face, in meters; H′ is the average thickness of the residual coal in the goaf, in meters; v CO The CO gas generation rate of residual coal at different oxidation stages is given in m³ / s. 3 / (min·g); Q is the air supply volume to the working face in the goaf, in m³ / g. 3 / min; η is the air leakage rate of the working face in the goaf; ρ is the density of the residual coal in the goaf, in g / m³. 3 .

[0012] Furthermore, the value of η above ranges from 0.06 to 0.10.

[0013] Furthermore, in step one above, the programmed heating process includes: heating the residual coal in the goaf in the first stage and then heating it in the second stage; preferably, the temperature range of the first stage heating is 20-80℃, and the heating rate is 0.5℃ / min; preferably, the temperature range of the second stage heating is 80-350℃, and the heating rate is 1℃ / min.

[0014] Furthermore, the aforementioned different oxidation stages include room temperature oxidation stage, slow oxidation stage, rapid oxidation stage, and intense oxidation stage.

[0015] Furthermore, the temperature of the above-mentioned room temperature oxidation stage is 20-50℃; the temperature of the slow oxidation stage is 50-150℃; the temperature of the rapid oxidation stage is 150-250℃; and the temperature of the violent oxidation stage is above 250℃.

[0016] By applying the technical solution of this application, this invention first determines the influence coefficients of each factor on CO gas generation based on the influence of factors such as working face advance speed, residual coal gas content, and goaf roof pressure on CO gas generation. Then, it combines the CO gas generation rate and influence coefficients in the goaf to obtain the critical value of CO gas. This method fully considers the influencing factors of CO gas generation in high-gas, easily spontaneously combustible coal seams and the oxidation characteristics of coal itself, making the determination method of CO gas critical value more scientific and accurate. It can ensure the timely detection of coal spontaneous combustion hazards in high-gas, easily spontaneously combustible coal seams and minimize the prevention and control costs of coal spontaneous combustion disasters in goaf areas, thereby ensuring safe production in the mine, improving mine production efficiency and economic benefits. Moreover, this method has the advantages of simple application, low investment cost, convenient use, and scientific and reliable judgment results. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0018] Figure 1 A flowchart for calculating the critical value of CO gas in a goaf of a high-gas, easily self-igniting coal seam, according to Embodiment 1 of the present invention, is shown. Detailed Implementation

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0020] As analyzed in the background section of this application, the existing methods for determining the critical value of CO gas in the goaf of high-gas, spontaneously combustible coal seams have limitations. To solve this problem, this application provides a method for determining the critical value of CO gas in high-gas, spontaneously combustible coal seams.

[0021] In a typical embodiment of this application, a method for calculating the critical value of CO gas in high-gas, spontaneously combustible coal seams is provided, such as... Figure 1 As shown, the calculation method includes the following steps: Step 1, based on the gas chromatography analysis of coal seam spontaneous combustion indicators and the index optimization method, a programmed temperature rise experiment is conducted on the residual coal in the goaf to obtain the CO gas generation rate v of the residual coal at different oxidation stages. COStep 2: Measure the air supply volume of the working face in the goaf, the air leakage rate of the working face in the goaf, the advancing speed of the working face, the width of the spontaneous combustion heat dissipation zone of the coal in the goaf, the width of the spontaneous combustion oxidation zone of the coal in the goaf, the periodic pressure step distance of the working face, the burial depth of the working face, the gas content of the coal seam, and the residual gas content of the remaining coal in the goaf. Step 3: Determine the influence coefficients of the advancing speed of the working face, the gas content of the remaining coal, and the roof pressure of the goaf on the critical value of CO gas in the goaf of high-gas, easily spontaneously combustible coal seams. Determine the critical value of CO gas in the goaf of high-gas, easily spontaneously combustible coal seams based on the CO gas generation rate and the influence coefficients.

[0022] This invention first determines the influence coefficients of various factors on CO gas generation based on the working face advance speed, residual coal gas content, and goaf roof pressure. Then, it combines the CO gas generation rate and influence coefficients within the goaf to obtain the critical CO gas value. This method fully considers the influencing factors of CO gas generation in high-gas, spontaneously combustible coal seams and the oxidation characteristics of coal itself, making the determination of the CO gas critical value more scientific and accurate. It ensures timely detection of spontaneous combustion hazards in high-gas, spontaneously combustible coal seams and minimizes the prevention and control costs of such disasters, thus guaranteeing safe mine production, improving mine efficiency, and increasing economic benefits. Furthermore, this method has advantages such as simple application, low investment cost, ease of use, and scientific and reliable judgment results.

[0023] In one embodiment of this application, the influence coefficient K1 of the working face advance speed on the critical value of CO gas is calculated by the following relationship (1):

[0024]

[0025] Where v0 is the working face advancing speed when measuring working face parameters, in m / d; v1 is the working face advancing speed when applying CO gas critical value, in m / d.

[0026] The above relationship (1) can be used to obtain a more accurate influence coefficient K1 of the working face advance speed on the critical value of CO gas.

[0027] In one embodiment of this application, the influence coefficient K2 of the above-mentioned residual coal gas content on the CO gas critical value is calculated by the following relationship (2):

[0028]

[0029] Where V0 is the gas content of the coal seam, in m³. 3 / t; V1 represents the residual gas content of the coal in the goaf, in m³. 3 / t; V′ is the relative gas emission rate in the mine, in m³. 3 / t.

[0030] The above relationship (2) can be used to obtain the more accurate influence coefficient K2 of the residual coal gas content on the critical value of CO gas.

[0031] In one embodiment of this application, the influence coefficient K3 of the above-mentioned goaf roof pressure on the critical value of CO gas is calculated by the following relationship (3):

[0032]

[0033] Where x is the distance from the working face within the goaf, in meters; k is a coefficient; L is the periodic pressure step distance of the working face, in meters; and H is the burial depth of the residual coal in the goaf, in meters.

[0034] The above relationship (3) makes the influence coefficient K3 of the roof pressure in the goaf on the critical value of CO gas more accurate.

[0035] In some embodiments of this application, when H≤600, k=10, and when H>600, k=5.

[0036] Based on the different burial depths of the coal residue in the goaf, there are different k values, which makes the influence coefficient K3 of the goaf roof pressure on the critical value of CO gas determined by the relationship (3) more accurate.

[0037] In some embodiments of this application, the above-mentioned CO gas critical value It is calculated from the following relation (4):

[0038]

[0039] L1 is the width of the spontaneous combustion heat dissipation zone of coal in the goaf, in meters; L2 is the width of the spontaneous combustion oxidation zone of coal in the goaf, in meters; L′ is the length of the working face, in meters; H′ is the average thickness of the residual coal in the goaf, in meters; v CO The CO gas generation rate of residual coal at different oxidation stages is given in m³ / s. 3 / (min·g); Q is the air supply volume to the working face in the goaf, in m³ / g. 3 / min; η is the air leakage rate of the working face in the goaf; ρ is the density of the residual coal in the goaf, in g / m³. 3 .

[0040] The critical value of CO gas obtained by the above relationship (4) is obtained. This more precise method makes the determination of CO gas critical values ​​more scientific and accurate. It can ensure the timely detection of coal spontaneous combustion hazards in high-gas, easily combustible coal seams, and minimize the prevention and control costs of coal spontaneous combustion disasters in goaf areas. This will ensure safe production in mines and improve mine production efficiency and economic benefits.

[0041] In some embodiments of this application, the value of η is 0.06 to 0.10.

[0042] The above range of η values ​​includes the air leakage rate of different working faces in the goaf, making the method of determining the critical value of CO gas by the relationship (4) more universal.

[0043] Preferably, in step one above, the programmed heating process includes: first heating the residual coal in the goaf, followed by a second heating; preferably, the temperature range of the first heating stage is 20–80℃, and the heating rate is 0.5℃ / min; preferably, the temperature range of the second heating stage is 80–350℃, and the heating rate is 1℃ / min. This makes the method for calculating the critical CO gas value in the goaf of high-gas, easily spontaneously combustible coal seams of this application more universally applicable to the spontaneous combustion oxidation stage of residual coal in the goaf.

[0044] In one embodiment of this application, the different oxidation stages include a room temperature oxidation stage, a slow oxidation stage, a rapid oxidation stage, and a violent oxidation stage.

[0045] The above different oxidation stages cover different stages of oxidation of residual coal in the goaf of high-gas, easily spontaneously combustible coal seams, thus enabling timely detection of coal spontaneous combustion disaster risks at each stage of spontaneous combustion of residual coal in the goaf of high-gas, easily spontaneously combustible coal seams.

[0046] In some embodiments of this application, the temperature of the above-mentioned room temperature oxidation stage is 20-50°C; the temperature of the slow oxidation stage is 50-150°C; the temperature of the rapid oxidation stage is 150-250°C; and the temperature of the violent oxidation stage is above 250°C.

[0047] The above different oxidation stages represent the various stages of oxidation that may occur when performing programmed temperature rise experiments on residual coal in goaf areas of high-gas, easily spontaneously combustible coal seams. Each oxidation stage has a meaning known in the art and will not be elaborated here.

[0048] Among them, marker gas chromatography analysis refers to the method of judging the ignition state by analyzing gases produced during the spontaneous combustion and oxidation process of coal, such as CO, C2H4, C2H2, alkane-to-alkene ratio, and alkanes-to-alkane ratio. The concentration, rate of gas production, and ratios between specific gases during the oxidation and heating process exhibit certain mathematical patterns related to their own temperature. In practical mine applications, the concentration of one or more marker gases is monitored by a bundled tube or manually sampled to determine the spontaneous combustion process of coal. Predictions can be made using the rate of increase of certain gas components or the ratio changes between certain gas components.

[0049] The indicator selection method refers to the selection method based on sensitivity, regularity, measurability, early manifestation, uniqueness, and monotonicity.

[0050] The beneficial effects of this application will be further illustrated below with reference to the embodiments.

[0051] Example 1

[0052] Taking a certain mine in Wuhai Energy as an example, referencing Figure 1 The flowchart shown illustrates the calculation of the critical CO gas value in high-gas, spontaneously combustible coal seams, including the following steps:

[0053] Step 1: A programmed heating experiment was conducted on the residual coal in the goaf. The temperature was first increased from 20℃ to 80℃ at a rate of 0.5℃ / min; then increased from 80℃ to 350℃ at a rate of 1.0℃ / min. The CO gas generation rate during the slow oxidation stage of the residual coal was found to be 4.1 × 10⁻⁶. -10 m 3 / (min·g), the CO gas generation rate in the rapid oxidation phase is 10×10 -10 m 3 / (min·g), the CO gas generation rate during the vigorous oxidation phase is 42.5×10 / (min·g). -10 m 3 / (min·g).

[0054] Step 2: The measured air supply volume at the working face is 2000 m³ / h. 3 / min, air leakage rate of 6%, working face advance speed of 3m / d, width of coal spontaneous combustion heat dissipation zone in goaf of 30m, width of spontaneous combustion oxidation zone of 40m, periodic pressure step distance of working face of 20m, burial depth of working face of 300m, gas content of coal seam after extraction of 5m 3 / t, residual gas content is 1.48m 3 / t.

[0055] Step 3: When the parameters are measured, the advancing speed of the working face is 3 m / d. When the CO gas critical value is applied, the advancing speed of the working face is 3.2 m / d. According to the relationship (1), the influence coefficient of the advancing speed of the working face on the CO gas critical value is calculated to be 1.07.

[0056] The gas content of the coal seam after extraction is 5m. 3 / t, residual gas content is 1.48m 3 / t, the relative gas emission rate of the mine is 12m³. 3 / t, according to the relationship (2), the influence coefficient of the gas content of the residual coal on the critical value of CO gas is calculated to be 1.36.

[0057] The coal seam is buried at a depth of 300m, and the periodic pressure step of the roof of the working face is 20m, with k set to 10. Based on the relationship (3), the calculation shows that when the distance from the working face to the goaf is less than or equal to 20m, the influence coefficient of the roof pressure on the critical value of CO gas is 0.95; when the distance from the working face to the goaf is greater than 20m, the influence coefficient of the roof pressure on the critical value of CO gas is 0.9.

[0058] Step 4: The working face is 200m long, the average thickness of the residual coal in the goaf is 0.5m, and the density of the residual coal is 1.38×10⁻⁶. 6 g / m 3 Based on equation (4), the critical values ​​of CO gas at different oxidation stages of the coal in the goaf are calculated and shown in the table below:

[0059] Oxidation stage room temperature oxidation stage slow oxidation stage rapid oxidation stage Intense oxidation stage Critical value (ppm) <43.9 43.9～107.1 107.1～455.2 >455.2

[0060] When the CO gas concentration is below 43.9 ppm, the residual coal in the goaf is in the normal temperature oxidation stage; when the CO gas concentration is between 43.9 and 107.1 ppm, the residual coal in the goaf is in the slow oxidation stage; when the CO gas concentration is between 107.1 and 455.2 ppm, the residual coal in the goaf is in the slow oxidation stage; when the CO gas concentration is above 455.2 ppm, the residual coal in the goaf is in the violent oxidation stage.

[0061] Based on the calculated CO gas critical value, a prediction and forecasting index system for different stages of coal spontaneous combustion oxidation in a certain working face of a mine in Wuhai Energy was established using the above method. The system successfully predicted and forecasted the spontaneous combustion of residual coal in the goaf of a certain working face, effectively preventing the occurrence of coal spontaneous combustion disasters and secondary disasters in the goaf.

[0062] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0063] This invention first determines the influence coefficients of various factors on CO gas generation based on the working face advance speed, residual coal gas content, and goaf roof pressure. Then, it combines the CO gas generation rate and influence coefficients within the goaf to obtain the critical CO gas value. This method fully considers the influencing factors of CO gas generation in high-gas, spontaneously combustible coal seams and the oxidation characteristics of coal itself, making the determination of the CO gas critical value more scientific and accurate. It ensures timely detection of spontaneous combustion hazards in high-gas, spontaneously combustible coal seams and minimizes the prevention and control costs of such disasters, thus guaranteeing safe mine production, improving mine efficiency, and increasing economic benefits. Furthermore, this method has advantages such as simple application, low investment cost, ease of use, and scientific and reliable judgment results.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for calculating the critical value of CO gas in the goaf of a high-gas, spontaneously combustible coal seam, characterized in that, The calculation method includes the following steps: Step 1: Based on the gas chromatography analysis and index optimization method for spontaneous combustion indicators of coal seams, a programmed temperature rise experiment was conducted on the residual coal in the goaf to obtain the CO gas generation rate of the residual coal at different oxidation stages. ; Step 2: Measure the air supply volume of the goaf working face, the air leakage rate of the goaf working face, the working face advance speed, the width of the coal spontaneous combustion heat dissipation zone in the goaf, the width of the coal spontaneous combustion oxidation zone in the goaf, the periodic pressure step distance of the working face, the burial depth of the working face, the gas content of the coal seam, and the residual gas content of the coal in the goaf. Step 3: Determine the influence coefficients of the working face advance speed, residual coal gas content, and goaf roof pressure on the CO gas critical value of the goaf of the high-gas easily spontaneously combustible coal seam; and determine the CO gas critical value of the goaf of the high-gas easily spontaneously combustible coal seam based on the CO gas generation rate and the influence coefficients. The influence coefficient of the working face advance speed on the critical value of CO gas K 1 is calculated from the following relation (1): （1） in, v 0 represents the working face advancing speed when measuring working face parameters, in m / d; v 1 represents the working face advance speed when the aforementioned CO gas critical value is applied, in m / d; The influence coefficient of the residual coal gas content on the critical value of CO gas. K 2 is calculated from the following relation (2): （2） in, V 0 represents the gas content of the coal seam, in m³. 3 / t; V 1 represents the residual gas content of the coal in the goaf, in cubic meters. 3 / t; This refers to the relative gas emission rate in the mine, expressed in cubic meters (m³). 3 / t; The influence coefficient of the roof pressure in the goaf on the critical value of CO gas. K 3 is calculated from the following relation (3): （3） in, x This refers to the distance from the working face within the goaf, expressed in meters (m). k For coefficients; L The step distance is determined by the period of the working surface, in meters. H The depth of the coal seam in the goaf, in meters; When H≤600, k=10; when H>600, k=5. The CO gas critical value φ (CO) is calculated using the following relation (4): （4） L 1 represents the width of the coal spontaneous combustion heat dissipation zone in the goaf, in meters; L 2 represents the width of the coal spontaneous combustion oxidation zone in the goaf, in meters; L′ The length of the working surface is in meters (m). H ′ represents the average thickness of residual coal in the goaf, in meters; The CO gas generation rate of the residual coal at different oxidation stages is given in m³ / s. 3 / (min·g); Q Air supply volume for the working face in the goaf, in m³ 3 / min; η The air leakage rate of the working face in the goaf; ρ The density of residual coal in the goaf, in g / m³ 3 .

2. The calculation method according to claim 1, characterized in that, The η The value ranges from 0.06 to 0.

10.

3. The calculation method according to claim 1, characterized in that, In step one, the temperature rise process includes: After the first stage of heating, the residual coal in the goaf is heated in a second stage.

4. The calculation method according to claim 3, characterized in that, The temperature range of the first stage of heating is 20~80℃, and the heating rate is 0.5℃ / min; The second stage of heating has a temperature range of 80~350℃ and a heating rate of 1℃ / min.

5. The calculation method according to claim 1, characterized in that, The different oxidation stages include room temperature oxidation stage, slow oxidation stage, rapid oxidation stage, and intense oxidation stage.

6. The calculation method according to claim 5, characterized in that, The temperature of the ambient temperature oxidation stage is 20~50℃; The temperature of the slow oxidation stage is 50~150℃; The temperature of the rapid oxidation stage is 150~250℃; The temperature during the intense oxidation phase is above 250°C.

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