Method for analyzing residual amounts of CH4 and CO2 in coal sample

Abstract

The invention provides a method for analyzing residual amounts of CH4 and CO2 in a coal sample, which comprises the following steps: (1) under normal pressure, placing the coal sample in a coal sample tank for natural analysis, collecting and analyzing the gas analysis amount Q normal pressure natural in the natural analysis process; (2) after natural analysis, starting a crushing mechanism in the coal sample tank for crushing until the particle size of 60% or more of the coal sample is 0.30 mm or less, collecting and analyzing the gas analysis amount Q in the crushing process, and naturally crushing; (3) analyzing the crushed coal sample particles under a negative pressure condition, and collecting and analyzing the gas analysis quantity Q negative pressure under the negative pressure condition; and (4) calculating to obtain the accumulated analysis quantity Q accumulation of the coal sample, wherein Q accumulation is equal to Q normal pressure natural + Q crushing natural + Q negative pressure. According to the analysis method, analysis gas released in coal natural analysis, crushing analysis and negative pressure analysis of the coal sample in after-mine activity is covered, and the residual amount of CH4 / CO2 in the coal sample can be measured more accurately.

Description

Technical Field

[0001] This invention relates to the technical field of analytical testing and ecological environment, specifically to a method for analyzing the residual amounts of CH4 and CO2 in coal samples. Background Technology

[0002] CO2 and CH4 are important greenhouse gases. The mining and utilization of fossil fuel coal is a significant source of CO2 and CH4 emissions. Therefore, accurately measuring the CO2 and CH4 content in coal is crucial for controlling greenhouse gas emissions.

[0003] Coal mining and post-mining activities are two key categories of methane escape emissions from my country's coal industry, accounting for a significant proportion of the country's total methane emissions. Post-mining activities mainly refer to the escape emissions of CH4 and CO2 during coal processing, utilization, storage, and transportation. Because coal is mostly in an open or semi-open system, it is difficult to accurately measure the emissions from this process. Currently, the emission factor calculation method is used, which multiplies the coal production over a period of time by the methane emission factor to obtain the methane emissions during that period. The aforementioned standards and guidelines specify default values ​​for the emission factor, but these default values ​​are generally a large regional or national average. This leads to significant discrepancies between the emissions calculated by enterprises using the default values ​​and the actual emissions, especially in low-gas-content mines.

[0004] Patent (201410388831.0) discloses a shale residual gas measurement system, which includes a rock sample sealed crushing device, a residual gas content measuring mechanism, and a computer. This system can achieve everything from the initial rock sample sealed crushing to the final residual gas content measurement. It is highly automated, simple to operate, and provides reliable measurement results. However, its processing capacity is small, and it can only measure under natural pressure, not under negative pressure.

[0005] Patent (202220452860.9) discloses a coal sample gas content measuring device. This device measures the gas content of coal samples under normal pressure. The main feature of this device is the addition of a placement box that fits into the coal sample container, which facilitates the cleaning of the coal sample container. However, the insertion and removal of the coal sample box will cause unmeasurable CH4 and CO2 to escape.

[0006] Therefore, there is an urgent need to develop an accurate method for measuring the residual CH4 / CO2 content in coal samples to improve the quality of carbon emission data in the coal industry. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a method for analyzing the residual amounts of CH4 and CO2 in coal samples based on the characteristics of CO2 and CH4 desorption rates in coal, thereby accurately determining the residual amounts of CH4 / CO2 in coal samples.

[0008] To achieve the objectives of this invention, the following technical solution is adopted:

[0009] This invention provides a method for analyzing the residual amounts of CH4 and CO2 in coal samples, comprising the following steps;

[0010] (1) Under normal pressure, the coal sample is placed in a coal sample container for natural desorption, and the amount of gas desorption Q during the natural desorption process is collected and analyzed. 常压自然 ;

[0011] (2) After natural desorption, the crushing mechanism in the coal sample container is activated to crush the coal until more than 60% of the coal sample has a particle size of less than 0.30 mm. The gas desorption amount Q during the crushing process is collected and analyzed. 破碎自然 ;

[0012] (3) The crushed coal sample particles were subjected to desorption under negative pressure conditions, and the amount of gas desorption Q under negative pressure conditions was collected and analyzed. 负压 ;

[0013] (4) Calculate the cumulative analytical volume Q of the coal sample. 累计 Q 累计 =Q 常压自然 +Q 破碎自然 +Q 负压 .

[0014] In some specific implementations, before starting the analytical determination step (1), the sealing performance of the coal sample container and the crushing mechanism in the coal sample container is checked to ensure the accuracy of the analytical determination process.

[0015] The coal samples that can be selected for the analytical method of this invention include coking coal, bituminous coal, long bituminous coal, and lignite.

[0016] In a specific embodiment of the analytical method of the present invention, the natural analytical process described in step (1) is carried out at normal pressure at 60-100°C. In some preferred embodiments, the natural analytical process is carried out at 90-98°C, for example, 92°C, 95°C, or 97°C.

[0017] In some specific implementations, the natural parsing time is at least 0.5 hours, preferably 2 to 4 hours, for example, 3 hours.

[0018] In a specific embodiment of the analytical method of the present invention, the crushing process in step (2) is carried out under normal pressure.

[0019] In the analytical method provided by the present invention, the crushing process in step (2) is stopped when more than 80% (mass percentage) of the coal sample has a particle size of less than 0.25 mm. For example, the crushing process is stopped when more than 85% (mass percentage) of the coal sample has a particle size of less than 0.2 mm.

[0020] In the analytical method provided by the present invention, in step (3), the analytical time is 0.2 to 12 hours under negative pressure, preferably 0.5 to 4 hours, for example, 1 hour, 2 hours, or 3 hours.

[0021] In some specific implementations, the negative pressure condition mentioned in step (3) is generally 0.1 to 10 kPa, preferably 1 to 5 kPa, such as 2 kPa, 3 kPa, or 4 kPa.

[0022] The above technical solution achieves the following technical effects:

[0023] The analytical method provided by this invention covers the content of analytical gases released from coal samples during natural analytical, crushing analytical, and negative pressure analytical processes in post-mining activities. Furthermore, it can accurately determine the residual amounts of CH4, CO2, and other gases in coal samples through further analysis.

[0024] The analytical method provided by this invention can realize the quantitative measurement of the analytical process of coal adsorbed gas under different conditions. It also realizes the continuous analytical process of natural analytical process, crush analytical process and negative pressure analytical process, overcoming the disadvantage that natural analytical process and negative pressure analytical process cannot be continuous. Detailed Implementation

[0025] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0026] Example 1

[0027] (1) Determine the sealing performance of the coal sample container and the structural integrity of the crushing mechanism.

[0028] (2) At normal pressure and 95℃, 10KG of fresh bituminous coal was placed in a coal sample container for natural desorption for 4h. The amount of gas desorption during the natural desorption process, Q, was collected and analyzed. 常压自然 ;

[0029] (3) After natural desorption, the coal sample was crushed by the crusher in the coal sample container at 95°C under normal pressure until more than 80% of the coal sample particles were below 0.25 mm. The gas desorption amount Q during the crushing process was collected and analyzed. 破碎自然 ;

[0030] (3) The crushed coal sample particles were subjected to desorption under a negative pressure of 0.1 kPa for 2 hours, and the amount of gas desorption under the negative pressure was collected and analyzed, Q. 负压 ;

[0031] (4) Calculate the cumulative analytical volume Q of the coal sample. 累计 Q 累计 =Q 常压自然 +Q 破碎自然 +Q 负压 .

[0032] Example 2

[0033] (1) Determine the sealing performance of the coal sample container and the structural integrity of the crushing mechanism;

[0034] (2) At normal pressure and 90℃, 10KG of fresh bituminous coal was placed in a coal sample container for natural desorption for 4h. The amount of gas desorption during the natural desorption process, Q, was collected and analyzed. 常压自然 ;

[0035] (3) After natural desorption, the coal sample was crushed by the crusher in the coal sample container at normal pressure and 90℃ until more than 80% of the coal sample particles were below 0.25mm. The gas desorption amount Q during the crushing process was collected and analyzed. 破碎自然 ;

[0036] (3) The crushed coal sample particles were subjected to desorption under a negative pressure of 1 kPa for 4 hours, and the amount of gas desorption under the negative pressure was collected and analyzed, Q. 负压 ;

[0037] (4) Calculate the cumulative analytical volume Q of the coal sample. 累计 Q 累计 =Q 常压自然 +Q 破碎自然 +Q 负压 .

[0038] Example 3

[0039] (1) Determine the sealing performance of the coal sample container and the structural integrity of the crushing mechanism;

[0040] (2) At normal pressure and 95℃, 10KG of fresh bituminous coal was placed in a coal sample container for natural desorption for 2h. The amount of gas desorption during the natural desorption process, Q, was collected and analyzed. 常压自然 ;

[0041] (3) After natural desorption, the coal sample was crushed by the crusher in the coal sample container at 95°C under normal pressure until more than 80% of the coal sample particles were below 0.25 mm. The gas desorption amount Q during the crushing process was collected and analyzed. 破碎自然 ;

[0042] (3) The crushed coal sample particles were subjected to desorption under a negative pressure of 5 kPa for 2 hours, and the amount of gas desorption under the negative pressure was collected and analyzed, Q. 负压 ;

[0043] (4) Calculate the cumulative analytical volume Q of the coal sample. 累计 Q 累计 =Q 常压自然 +Q 破碎自然 +Q 负压 .

[0044] Example 4

[0045] (1) Determine the sealing performance of the coal sample container and the structural integrity of the crushing mechanism;

[0046] (2) At normal pressure and 90℃, 10KG of fresh bituminous coal was placed in a coal sample container for natural desorption for 2h. The amount of gas desorption during the natural desorption process, Q, was collected and analyzed. 常压自然 ;

[0047] (3) After natural desorption, the coal sample was crushed by the crusher in the coal sample container at normal pressure and 90℃ until more than 80% of the coal sample particles were below 0.25mm. The gas desorption amount Q during the crushing process was collected and analyzed. 破碎自然 ;

[0048] (3) The crushed coal sample particles were subjected to desorption under a negative pressure of 1 kPa for 2 hours, and the amount of gas desorption under the negative pressure was collected and analyzed, Q. 负压 ;

[0049] (4) Calculate the cumulative analytical volume Q of the coal sample. 累计 Q 累计 =Q 常压自然 +Q 破碎自然 +Q 负压 .

[0050] Example 5

[0051] (1) Determine the sealing performance of the coal sample container and the structural integrity of the crushing mechanism;

[0052] (2) At normal pressure and 98℃, 10KG of fresh bituminous coal was placed in a coal sample container for natural desorption for 2h. The amount of gas desorption during the natural desorption process, Q, was collected and analyzed. 常压自然 ;

[0053] (3) After natural desorption, the coal sample was crushed by the crusher in the coal sample container at 98°C under normal pressure until more than 80% of the coal sample particles were below 0.25 mm. The gas desorption amount Q during the crushing process was collected and analyzed. 破碎自然 ;

[0054] (3) The crushed coal sample particles were subjected to desorption under a negative pressure of 10 kPa for 4 hours, and the amount of gas desorption under the negative pressure condition, Q, was collected and analyzed. 负压 ;

[0055] (4) Calculate the cumulative analytical volume Q of the coal sample. 累计 Q 累计 =Q 常压自然 +Q 破碎自然 +Q 负压 .

[0056] Comparative Example 1

[0057] (1) Determine the sealing performance of the coal sample container and the structural integrity of the crushing mechanism;

[0058] (2) At normal pressure and 90℃, 500g of fresh bituminous coal was placed in a coal sample container for natural desorption for 4h. The amount of gas desorption during the natural desorption process, Q, was collected and analyzed. 常压自然 ;

[0059] (3) After natural desorption, the coal sample is kept in the coal sample container and crushed by the crushing and pulverizing mechanism at normal pressure and 90℃ until more than 80% of the coal sample particles are below 0.25mm. The gas desorption amount Q during the crushing process is collected and analyzed. 破碎自然 ;

[0060] (4) Calculate the cumulative analytical volume Q of the coal sample. 累计 Q 累计 =Q 常压自然 +Q 破碎自然 .

[0061] Comparative Example 2

[0062] (1) Determine the sealing performance of the coal sample container and the structural integrity of the crushing mechanism;

[0063] (2) Take 500g of fresh bituminous coal and place it in a coal sample container. At normal pressure and 90℃, start the crushing and pulverizing mechanism to crush it until more than 80% of the coal sample particles are below 0.25mm. Perform crushing and desorption for 4 hours, and collect and analyze the gas desorption amount Q during the crushing process. 破碎自然 ;

[0064] (3) After crushing and desorption, the coal sample is kept in the coal sample container and connected to a negative pressure system with a pre-evacuation pressure of 1 kPa for negative pressure desorption for 4 hours. The amount of gas desorbed during the negative pressure desorption process, Q, is collected and analyzed. 负压 ;

[0065] (4) Calculate the cumulative analytical volume Q of the coal sample. 累计 Q 累计 =Q 破碎自然 +Q 负压 .

[0066] The amount of desorbed gas collected using the above implementation methods is shown in Table 1 below:

[0067] Table 1

[0068] <![CDATA[Q 常压自然 ]]> <![CDATA[Q 破碎自然 ]]> <![CDATA[Q 负压 ]]> <![CDATA[Q 累计 ]]> Example 1 0.21 0.98 0.57 1.76 Example 2 0.20 0.95 0.48 1.63 Example 3 0.21 0.96 0.48 1.65 Example 4 0.17 0.85 0.39 1.41 Example 5 0.21 1.01 0.49 1.71 Comparative Example 1 0.16 0.73 - 0.89 Comparative Example 2 - 0.65 0.32 0.97

[0069] Note: The unit for the content of each desorbed gas in Table 1 is ml / g.

[0070] The desorbed gases collected through the above implementation methods were pumped into a gas chromatograph using an automatic gas inlet pump for gas analysis. The component contents are shown in Table 2 below.

[0071] Table 2

[0072]

[0073]

[0074] Note: The unit of concentration for each gas in Table 2 is ml / g.

[0075] As can be seen from the data in Tables 1 and 2 above, the analytical method provided by this invention covers the analytical gases released during the natural analytical process, crushing analytical process, and negative pressure analytical process of coal samples. It can more accurately determine the analytical gas content of coal samples, and through analysis, it can obtain the residual amounts of CH4 and CO2 released from the coal samples at each stage, so as to guide carbon emission control in the coal industry.

Claims

1. A method for analyzing residual amounts of CH4 and CO2 in a coal sample, characterized by, The method comprises the following steps: (1) The coal sample is placed in a coal sample canister under normal pressure to perform natural resolution, and the amount of gas resolution Q during the natural resolution process is collected and analyzed 常压自然 ; (2) After the natural analysis, the crushing mechanism in the coal sample jar is started to crush until more than 60% of the coal sample has a particle size of 0.30 mm or less, and the gas analysis amount Q of the crushing process is collected and analyzed 破碎自然 ; (3) The coal sample particles after crushing are resolved under a negative pressure condition, and the amount of gas resolution Q under the negative pressure condition is collected and analyzed 负压 ; (4) The cumulative amount of desorption Q of the coal sample is calculated 累计 , Q 累计 = Q 常压自然 + Q 破碎自然 + Q 负压 .

2. The resolution method according to claim 1, wherein, Before step (1), check the sealing performance of the coal sample jar.

3. The resolution method according to claim 2, wherein, In step (1), the coal sample is subjected to natural desorption at 60-100℃ under normal pressure.

4. The resolution method according to claim 3, wherein, The coal sample is subjected to natural desorption at 90-98℃.

5. The resolution method according to claim 3, wherein, The desorption time of the natural desorption is at least 0.5h, preferably 2-4h.

6. The analysis method according to any one of claims 1 to 5, characterized by, In step (2), the crushing process is carried out under normal pressure.

7. The resolution method according to claim 6, wherein, The particle size of the crushed coal sample is less than 0.25mm.

8. The analysis method according to any one of claims 1 to 7, characterized by, In step (3), the desorption is carried out under negative pressure for 0.2-12h, preferably 0.5-4h.

9. The resolution method according to claim 8, wherein, The negative pressure is 0.1-10kPa.

10. The resolution method according to claim 9, wherein, The negative pressure is 1-5kPa.

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