Coal blending method and use thereof

Abstract

A coal blending method and a use thereof, relating to the technical field of thermal power engineering, and solving the problems of low-temperature oxidation, spontaneous combustion and pollutant formation in stored coal. The specific method is as follows: selecting coal M and coal N, and blending same at a specific ratio, wherein the coal M has an oxygen uptake weight gain ΔM>1% and Vdaf>37%, the coal N has an oxygen uptake weight gain ΔM≤1% and Vdaf≤37%, and the weight ratio of the coal M to the coal N is (10-90): (10-90); the oxygen uptake weight gain ΔM=M2-M1, ΔM is the difference between the peak and valley values during the oxygen uptake weight gain stage in a thermogravimetric test, M1 is the valley value of a thermogravimetric curve, M2 is the peak value of the thermogravimetric curve, and Vdaf is the dry ash‑free volatile matter of coal.

Description

Coal mixing method and application thereof TECHNICAL FIELD

[0001] The present application relates to the technical field of thermal power engineering, in particular to a coal mixing method and application thereof. BACKGROUND

[0002] Low-temperature oxidation and spontaneous combustion of coal can reduce the calorific value of coal, reduce the value of coal as fuel, and also release harmful gases such as CO2, SO2, NO x , HCl, etc., which are harmful to the human body and pollute the atmosphere. Spontaneous combustion occurs when the heat accumulated by low-temperature oxidation of coal during stacking reaches a certain level, so it is necessary to start from inhibiting low-temperature oxidation to prevent spontaneous combustion. At present, the methods for inhibiting low-temperature oxidation are as follows: 1) layered compaction. By reducing the pores between coal particles through rolling, the entry of oxygen is reduced, which has a certain effect, but a large amount of manpower and material resources are consumed; 2) water cooling. By spraying water to reduce the temperature of the coal pile to achieve the effect of fire retardation, but the water evaporates easily, and the effect is limited; 3) spraying fire retardant or non-combustible substances. A covering layer is formed on the surface of the coal pile to block the air channel and reduce the entry of oxygen, but some chemicals have an impact on the environment; 4) filling inert gas around the coal pile, but it is easy to cause harm to the health of workers in the enclosed space.

[0003] Therefore, preventing low-temperature oxidation and spontaneous combustion of coal during stacking is a problem that needs to be solved urgently. SUMMARY

[0004] Therefore, the present application aims to overcome the shortcomings of the prior art and provide a coal mixing method for preventing low-temperature oxidation and spontaneous combustion of coal during stacking.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows: a coal mixing method, the specific method being as follows: selecting coal M and coal N, and mixing them according to a certain proportion; wherein the oxygen absorption weight gain of the coal M is greater than 1%, V daf is greater than 37%, the oxygen absorption weight gain of the coal N is less than or equal to 1%, V daf is less than or equal to 37%, and the weight ratio of the coal M to the coal N is (10-90):(10-90); the oxygen absorption weight gain ΔM=M2-M1, ΔM is the difference between the peak value and the valley value in the oxygen absorption weight gain stage in the thermogravimetric experiment, M1 is the valley value of the thermogravimetric experiment curve, M2 is the peak value of the thermogravimetric experiment curve, and V daf is the moisture-free ash-free basis volatile matter of coal.

[0006] The present application realizes the effect of preventing low-temperature oxidation and spontaneous combustion of coal during stacking by mixing two different types of coal M and coal N. The present inventors have found in actual experiments that the coal M and the coal N that meet the specific oxygen absorption weight gain ΔM and the specific V dafThe mixture of the coal M and the coal N is not a simple addition of the two coals, but has an interactive relationship. The mixture of the coal M and the coal N in a specific ratio has a phenomenon that the theoretical thermal weight loss value is greater than the measured thermal weight loss value at different temperatures, and the theoretical pollutant emission amount is greater than the measured pollutant emission amount, and the influence degree is different with different mixing ratios, which is closely related to the different water content and inorganic matter content in the coal. The greater the difference between the theoretical value and the measured value is, the more conducive to inhibiting oxidation and pollutant emission in the corresponding mixing ratio. The influence relationship for different coals is relatively complex, and there may be two aspects of inhibition, or only one aspect of inhibition. The purpose of inhibiting oxidation and pollutant emission is achieved by the mixing of the coals, which is simple and easy to implement and very environmentally friendly. daf The mixture of the coal M and the coal N in a specific ratio has a phenomenon that the theoretical thermal weight loss value is greater than the measured thermal weight loss value at different temperatures, and the theoretical pollutant emission amount is greater than the measured pollutant emission amount, and the influence degree is different with different mixing ratios, which is closely related to the different water content and inorganic matter content in the coal. The greater the difference between the theoretical value and the measured value is, the more conducive to inhibiting oxidation and pollutant emission in the corresponding mixing ratio. The influence relationship for different coals is relatively complex, and there may be two aspects of inhibition, or only one aspect of inhibition. The purpose of inhibiting oxidation and pollutant emission is achieved by the mixing of the coals, which is simple and easy to implement and very environmentally friendly.

[0007] Preferably, the weight ratio of the coal M and the coal N is 50:50-30:70.

[0008] The inventors found in the actual experiment that the weight ratio of the coal M and the coal N is 50:50-30:70, which is more conducive to inhibiting oxidation and pollutant emission.

[0009] Preferably, the mixing method is that the two coals are mixed repeatedly more than three times by using a two-partition device or are mixed uniformly by using an electric coal mixing device.

[0010] Preferably, the particle size of the coal M and the coal N is 60-100 mesh; and more preferably, the particle size of the coal M and the coal N is 80 mesh.

[0011] Preferably, the thermal gravimetric data of the coal M and the coal N are weighted and averaged to obtain the theoretical oxygen absorption weight gain ΔM of the mixed coal 理论 The function expression for the oxygen absorption weight gain of the mixed coal weighted according to the mass ratio is ΔM 理论 =x / 100×ΔM1+(100-x) / 100×ΔM2.

[0012] In the formula, ΔM 理论 is the weighted average value of the thermal gravimetric data of the mixed coal;

[0013] x / 100 and (100-x) / 100 are the weight percentage of the coal M and the coal N in the mixed coal; and ΔM1 and ΔM2 are the measured values of the oxygen absorption weight gain of the coal M and the coal N.

[0014] Preferably, the pollutant emission amount data of the coal M and the coal N are weighted and averaged to obtain the theoretical pollutant emission amount W of the mixed coal 理论 The function expression for the pollutant emission amount data of the mixed coal weighted according to the mass ratio is W 理论 =x / 100×W1+(100-x) / 100×W2.

[0015] In the formula: W 理论 is the additive average value of the pollutant emission of the mixed coal; x / 100, (100-x) / 100 are the weight percentages of the coal M and the coal N in the mixed coal; W1, W2 are the measured values of the pollutant emission of the coal M and the coal N.

[0016] Optionally, in the actual test process, the present application adopts the joint test of two instruments, the gas discharged from the TGA is sent to the beam uniform flow cell of the sample compartment of the infrared spectrum through the conveying pipe with the temperature of 215 DEG C, and then the content of the pollution gas is determined by the infrared spectrum.

[0017] Preferably, the thermogravimetric data of the coal M and the coal N are detected by the thermogravimetric analysis, and the test conditions of the thermogravimetric analysis are as follows: the sample is heated from 30 DEG C to 300 DEG C, the temperature rising rate is 3 DEG C / min, the air flow is 50 ml / min, and the sample amount is 10+ / -0.5 mg.

[0018] Preferably, the pollutant emission of the coal M and the coal N is detected by the Fourier transform infrared measuring instrument, and the test conditions of the Fourier transform infrared measuring instrument are as follows: the absorption spectrum wavelength of CO2 is 2360 cm -1 , the absorption spectrum wavelength of SO2 is 1342 cm -1 , the absorption spectrum wavelength of NO is 1762 cm -1 , and the absorption spectrum wavelength of HCl is 2798 cm -1 .

[0019] Further, the present application provides the application of the mixed coal method in the field of preventing spontaneous combustion of the stored coal.

[0020] Compared with the prior art, the present application has the following advantages: the present application solves the problems of the low-temperature oxidation, spontaneous combustion and pollutants of the stored coal. Compared with the existing flame retardant, the present application has the following advantages: (1) environmental protection. The present application does not use any chemical substances, does not affect the environment, and is non-toxic to the human body; (2) compared with the inert gas, the present application is not easy to cause the asphyxiation of the coal yard workers; (3) compared with the layered compaction, the present application only mixes and stacks the two different property coals according to the determined coal type and the best ratio in the process of unloading the coal, does not use the rolling equipment for rolling, and does not need to invest a large amount of manpower and material resources; (4) compared with the water spraying, the present application does not need to consume a large amount of water, and the effect is also durable. BRIEF DESCRIPTION OF DRAWINGS

[0021] Fig. 1 is a low-temperature oxidation TG curve diagram of single coal ABC. DETAILED DESCRIPTION

[0022] For better illustrating the purpose, technical scheme and advantages of the present application, the present application will be further explained in combination with the drawings and specific examples. The purpose is to understand the content of the present application in detail, but not to limit the present application. All other examples obtained by the ordinary skilled in the art without making creative efforts are within the protection scope of the present application. The experimental reagents and instruments designed in the implementation and comparative examples of the present application are common reagents and instruments unless specially stated, and can be obtained from commercial channels. The experimental methods used in the implementation and comparative examples are conventional methods unless specially stated, and the raw materials used in parallel experiments are the same batch of raw materials unless specially stated.

[0023] The raw materials used in the examples and comparative examples are described as follows, but are not limited to these materials:

[0024] Lignite-A: ΔM = 1.76%, V daf = 48.07%, source: Indonesian lignite;

[0025] Lignite-B: ΔM = 1.62%, V daf = 55.31%, source: Indonesian lignite;

[0026] Bituminous coal-C: ΔM = 0.21%, V daf = 36.10%, source: domestic bituminous coal;

[0027] Lignite-D: ΔM = 2.88%, V daf = 48.73%, source: Australian lignite;

[0028] Anthracite-E: ΔM = 0.16%, V daf = 9.87%, source: domestic anthracite;

[0029] Bituminous coal-F: ΔM = 1.68%, V daf = 37.90%, source: domestic bituminous coal;

[0030] Anthracite-G: ΔM = 0.26%, V daf = 11.98%, source: domestic anthracite;

[0031] Performance test 1 determination of mixing mode among coals

[0032] The coal samples were crushed into samples with particle size of 80 mesh, and the results of elemental analysis and industrial analysis of the samples were shown in Table 1. The thermodynamic parameters in the process of low-temperature oxidation of the coal samples were shown in Table 2. The thermodynamic parameters in the process of low-temperature oxidation of the mixed coal were shown in Table 3. The pollutant emission parameters of the single coal sample and the mixed coal were shown in Table 4.

[0033] Two kinds of coal samples (A and C samples) were mixed in the proportions of 10:90, 30:70, 50:50, 30:70, and 90:10, and were first subjected to thermogravimetric analysis, and then the above five kinds of mixed coal were subjected to infrared analysis to obtain the emission amounts of various pollutants. Two kinds of coal samples (D and E samples) were mixed in the proportions of 10:90, 30:70, 50:50, 30:70, and 90:10, and were first subjected to thermogravimetric analysis, and then the above five kinds of mixed coal were subjected to infrared analysis to obtain the emission amounts of various pollutants. Two kinds of coal samples (F and G samples) were mixed in the proportions of 10:90, 30:70, 50:50, 30:70, and 90:10, and were first subjected to thermogravimetric analysis, and then the above five kinds of mixed coal were subjected to infrared analysis to obtain the emission amounts of various pollutants.

[0034] Thermogravimetric analysis test method in Tables 2-3: 10 mg ± 0.5 mg of coal sample or mixed sample of each proportion was weighed and analyzed using a Swiss Mettler simultaneous thermogravimetric analyzer, and the test method was as follows: 10 ± 0.5 mg of sample was weighed using a sample pan and was placed in the thermogravimetric analyzer, and was heated from 30°C to 300°C at a heating rate of 3°C / min, and the sample was oxidized in an air atmosphere, and an air flow rate of 50 ml / min was introduced, and the thermogravimetric analysis was completed.

[0035] Test method for emission amounts of pollutants of mixed coal in Table 4: the gas discharged from the TGA was sent to the beam uniform flow cell of the sample compartment of the infrared spectrum through a conveying pipe with a temperature of 215°C, and then the content of the pollution gas was determined by infrared spectrum. The absorption spectrum wavelength of SO2 was 1342 cm -1 , the absorption spectrum wavelength of NO was 1762 cm -1 , and the absorption spectrum wavelength of HCl was 2798 cm -1 .

[0036] Elemental analysis and industrial analysis results in Table 1

[0037] Note: M ar - received basis moisture, M ad - air-dry basis moisture, A ad - air-dry basis ash, V ad - air-dry basis volatile matter, S ad - air-dry basis sulfur, FC ad - air-dry basis fixed carbon.

[0038] Thermodynamic parameters in the low-temperature oxidation process of single coal in Table 2

[0039] Thermodynamic parameters in the low-temperature oxidation process of mixed coal in Table 3

[0040] Note: M1 is the trough value of TG curve; T1 is the temperature corresponding to the trough; M2 is the peak value of TG curve; T2 is the temperature corresponding to the peak; ΔM is the difference between the peak and the trough TG values, ΔM = M2 - M1, wherein ΔM is the second stage oxygen uptake weight gain, thus also known as oxygen uptake weight gain, the greater the oxygen uptake weight gain, the easier the sample is oxidized, and vice versa.

[0041] Table 4 Synergistic effect of pollutant emissions (mL / L)

[0042] Figure 1 is a TG curve of low-temperature oxidation of single coal ABC. The low-temperature oxidation process of the coal is divided into two stages: 1) oxygen uptake and desorption stage (30-140°C), which is mainly physical adsorption, followed by chemical adsorption and chemical reaction. The active molecules or groups in the coal contact with oxygen and undergo oxidation reaction, and the temperature of the coal sample increases slowly. At the same time, the water in the coal begins to evaporate, and CO, CO2, CH4, H2S and other gases generated by the oxidation reaction. As the temperature increases, the physical adsorption changes to chemical adsorption, and the mass of the sample gradually decreases. 2) Oxygen uptake weight gain stage (150-260°C), which is mainly chemical adsorption and chemical reaction. In this stage, due to the evaporation of water and the release of gas in the first stage, the coal particles become gradually loose, and the adsorption capacity of oxygen increases. The mass of the coal sample increases with the increase of temperature, and the thermal gravimetric experiment curve (TG) reaches the highest point. The lowest point of the thermal gravimetric curve (TG) is the dividing point between the two stages.

[0043] As can be seen from Table 2 and Table 3, the ΔM 实测 value of A and B after mixing is greater than the ΔM 理论 value of A and B, and the ΔM 实测 value of A and B mixed with C sample is significantly smaller than the ΔM 理论 value of A and C sample (or B and C), indicating that the mixing of coal A and B promotes low-temperature oxidation and spontaneous combustion, and the mixing of coal A and C sample (or B and C) inhibits low-temperature oxidation and spontaneous combustion. Similarly, the inventors explored the difference between the ΔM 实测 value and the ΔM 理论 value of D coal and E coal, F coal and G coal after mixing in different proportions, and found that as long as the specific oxygen uptake weight gain ΔM and the specific V daf of the mixed coal M and coal N are met, the low-temperature oxidation is inhibited.

[0044] The weight ratio of coal M and coal N will further affect the oxidation inhibition effect.

[0045] As can be seen from Table 3, under the condition of a specific mixing ratio, the ΔM 实测 value and the ΔM 理论The difference value of the value is negative, indicating that the mixture has an inhibitory effect on low-temperature oxidation. When the mixing ratio of coal M and coal N is 50:50-30:70, ΔM 实测 The difference value of the value is negative, indicating that the mixture has an inhibitory effect on low-temperature oxidation. When the mixing ratio of coal M and coal N is 50:50-30:70, ΔM 理论 The difference value of the value is negative, indicating that the mixture has an inhibitory effect on low-temperature oxidation. When the mixing ratio of coal M and coal N is 50:50-30:70, ΔM x , HCl and other pollutants, and the absolute value of the difference is greater than that of other mixed coal ratios, which is more conducive to inhibiting pollutant emissions. The optimal mixing ratio range is determined to be 50:50-30:70. Considering the inhibition of low-temperature oxidation and pollutant emissions, the optimal mixing ratio is 50:50-30:70.

[0046] It can be seen that the mixing of coal is not a simple storage, but there is a synergistic or inhibitory effect between coal and coal. When the specific oxygen absorption weight ΔM and the specific V daf of coal M and coal N are met, the mixing of coal M and coal N is not a simple addition of two coals, but there is an interactive relationship. When the specific oxygen absorption weight ΔM and the specific V daf of coal M and coal N are met, the mixing of coal M and coal N at a specific ratio appears a phenomenon that the theoretical thermal weight loss value is greater than the measured thermal weight loss value at different temperatures, and the theoretical pollutant emission is greater than the measured pollutant emission. The difference between the theoretical value and the measured value is greater, indicating that the corresponding mixing ratio is more conducive to inhibiting oxidation and pollutant emissions. The influence relationship of different coals is relatively complex, which may exist in both aspects of inhibition, or may be one-sided. Through the way of mixed coal, the purpose of inhibiting oxidation and pollutant emissions is achieved, which is simple, easy and environmentally friendly.

[0047] The present application shows that by mixing three types of coal, lignite, bituminous coal and anthracite, the effect of preventing low-temperature oxidation and spontaneous combustion of coal during storage is achieved by mixing two different types of coal M and coal N, and the energy-saving and emission-reducing goals are achieved.

[0048] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and are not intended to limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A coal blending method characterized by, The specific method is as follows: selecting coal M and coal N, and mixing them according to a certain proportion; The oxygen absorption weight gain of the coal M is greater than 1%, V daf The oxygen absorption weight gain of the coal N is less than or equal to 1%, V daf The oxygen absorption weight gain of the coal M is greater than 1%, V daf The oxygen absorption weight gain of the coal N is less than or equal to 1%, V The oxygen absorption weight gain of the coal M is greater than 1%, V The oxygen absorption weight gain of the coal N is less than or equal to 1%, V The oxygen absorption weight gain of the coal M is greater than 1%, V The oxygen absorption weight gain of the coal N is less than or equal to 1%, V The oxygen absorption weight gain of the coal M is greater than 1%, V The oxygen absorption weight gain of the coal N is less than or equal to 1%, V The oxygen absorption weight gain of the coal M is greater than 1%, V The oxygen absorption weight gain of the coal N is less than or equal to 1%, V The oxygen absorption weight gain of the coal M is greater than 1%, V The oxygen absorption weight gain of the coal N is less than or equal to 1%, V The oxygen absorption weight gain of the coal M is greater than 1%, V The oxygen absorption weight gain of the coal N is less than or equal to 1%, V The oxygen absorption weight gain of the coal M is greater than 1%, V The oxygen absorption weight gain of the coal N is less than or equal to 2. The coal blending method of claim 1, wherein, The weight ratio of the coal M and the coal N is 50:50-30:

70.

3. The coal blending method of claim 1, wherein, The mixing method is: using a two-part mixer to mix more than three times repeatedly, or using an electric coal mixing device to mix uniformly.

4. The coal blending method of claim 1, wherein, The particle size of the coal M and the coal N is 60-100 mesh; preferably, the particle size of the coal M and the coal N is 80 mesh.

5. The coal blending method of claim 1, wherein, The thermal gravimetric data of the coal M and the coal N are weighted and averaged to obtain the theoretical oxygen absorption weight gain of the mixed coal ΔM 理论 The oxygen absorption weight gain function expression of the mixed coal obtained by the mass proportion weighting is: ΔM 理论 = x / 100 x ΔM1 + (100-x) / 100 x ΔM2 where: ΔM 理论 is the average of the thermogravimetric data for the mixed coal x / 100, (100-x) / 100 is the weight percentage of the coal M and the coal N in the mixed coal; ΔM1, ΔM2 is the measured value of the oxygen absorption weight gain of the coal M and the coal N.

6. The coal blending method of claim 1, wherein, The pollutant emission data of the coal M and the coal N are weighted and averaged to obtain the theoretical pollutant emission W of the mixed coal 理论 The function expression of the pollutant emission data of the mixed coal weighted according to the mass proportion is W 理论 =x / 100×W1+(100-x) / 100×W2 In the formula: W 理论 is the additive average value of the pollutant emission of the mixed coal; x / 100, (100-x) / 100 are the weight percentages of the coal M and the coal N in the mixed coal; W1, W2 are the measured values of the pollutant emission of the coal M and the coal N.

7. The coal blending method as claimed in claim 5, wherein, The thermogravimetric data of the coal M and the coal N is detected by thermogravimetric analysis, and the thermogravimetric analysis test conditions are: the sample is heated from 30 DEG C to 300 DEG C, the temperature rising rate is 3 DEG C / min, the air flow is 50 ml / min, and the sample amount is 10+ / -0.5 mg.

8. The coal blending method as claimed in claim 6, characterized in that, The pollutant emission amounts of the coal-fired M and the coal-fired N are detected by using a Fourier transform infrared measuring instrument. The Fourier transform infrared measuring instrument test conditions are as follows: the absorption spectrum wavelength of CO2 is 2360 cm -1 , the absorption spectrum wavelength of SO2 is 1342 cm -1 , the absorption spectrum wavelength of NO is 1762 cm -1 , and the absorption spectrum wavelength of HCl is 2798 cm -1 .

9. The application of the mixed coal method according to any one of claims 1-8 in the field of preventing spontaneous combustion of coal storage.

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