A test method for determining performance indicators of a retarder

Abstract

The application discloses a kind of test methods for determining inhibitor performance index, belong to coal mine safety technical field;Specifically related to the detection of inhibitor inhibition rate, inhibition life performance index of inhibitor.The application comprehensively considers the change rule of CO, C2H4 and C2H2 three gases in the process of coal oxidation spontaneous combustion and its advantages and disadvantages as index gas, combined with traditional test method, respectively calculate the inhibition rate of inhibitor in the whole stage of oxidation spontaneous combustion and oxidation spontaneous combustion substage: slow oxidation stage, accelerated oxidation stage and intense oxidation stage, and introduce gas generation rate to describe the inhibition effect of inhibitor in each substage, obtain the inhibition performance and inhibition rule of inhibitor in the whole process of oxidation spontaneous combustion;In the application, the whole stage inhibition rate and inhibition life are combined, the inhibition effect of inhibitor can be more comprehensively evaluated, and the selection of inhibitor type and concentration by technical personnel in the process of coal seam mining can be widely used.

Description

Technical Field

[0001] This invention belongs to the field of coal mine safety technology, and specifically relates to a test method for determining the performance indicators of inhibitors. Background Technology

[0002] Spontaneous combustion of coal seams is one of the major hazards affecting safe production in coal mines. Research on coal mine fire prevention and extinguishing technologies is of great significance for timely and effective prevention and control of coal mine fires, reducing coal resource waste, avoiding loss of life and property, and ensuring safe production. Among these technologies, spraying fire inhibitors is an important method for mine fire prevention and extinguishing.

[0003] In traditional inhibition rate testing methods, CO is typically used to determine the inhibition rate. Referring to the testing methods for the inhibition performance of inhibitors specified in the "General Technical Conditions for Inhibitors for Fire Prevention in Coal Mines," the inhibition rate E represents the ratio of the change in CO volume concentration released by the coal sample before and after inhibition at 100℃ to the CO volume concentration released from the original coal sample. However, this method has shortcomings. The inhibitory effect of the inhibitor on the coal sample is a continuously changing process. Traditional testing methods can only obtain the inhibition rate of the inhibitor at 100℃, failing to accurately reflect the inhibitory effect of the inhibitor throughout the entire process of coal oxidation and spontaneous combustion. Furthermore, the large temperature range when detecting CO also fails to accurately reflect the inhibition pattern of the inhibitor at different stages of coal oxidation, reducing the accuracy of the inhibition rate test results.

[0004] To address the inaccuracy of using only CO as the indicator for inhibition rate determination, a method for determining the inhibition performance of inhibitors, as described in CN105510175B (authorized publication number), proposes a method that combines staged gas release with existing CO release data to evaluate inhibition rate, further improving the accuracy of the results. However, current inhibitor performance indicators generally only consider inhibition rate, but not all inhibitors exhibit the pattern of higher inhibition rate leading to longer inhibition lifetime. Therefore, using only inhibition rate as a single indicator to evaluate the inhibitory effect does not allow for the scientific and rational selection of inhibitors.

[0005] Therefore, there is an urgent need for a method to determine the performance indicators of inhibitors, which can more reasonably evaluate the performance indicators of inhibitors from different perspectives and different inhibition stages, and provide more reference standards for the selection of inhibitors. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems existing in the prior art and provide a test method for determining the performance indicators of inhibitors. This method comprehensively considers the variation patterns of three stage indicator gases—CO, C2H4, and C2H2—in the coal oxidation and spontaneous combustion process, as well as their advantages and disadvantages as indicator gases. Combining traditional test methods, the inhibition rate of the inhibitor is calculated at different oxidation stages, and the gas generation rate is introduced to describe the inhibition effect of the inhibitor at each sub-stage. This yields the inhibition performance and inhibition pattern of the inhibitor throughout the entire oxidation and spontaneous combustion process, thereby improving the accuracy of the evaluation results.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a test method for determining the performance indicators of inhibitors, comprising the following steps:

[0008] S1. Weigh the raw coal sample and the prepared inhibited coal sample into the reaction tube respectively, put the reaction tube into the programmable temperature control box, connect the air pump, gas chromatograph and computer, and check the airtightness of the device.

[0009] S2. Turn on the programmable temperature control chamber and air pump, and raise the temperature from room temperature to 300℃ under normal pressure. Use a gas chromatograph to record the volume concentrations of CO, C2H4 and C2H2 generated at different temperatures for the raw coal sample and the inhibited coal sample, and plot the corresponding inhibition curves.

[0010] S3. Based on the volume fraction of CO, C2H4 and C2H2 as a function of temperature plotted in step S2 above, and combined with the formula for calculating the inhibition rate, the inhibition rate E of the inhibitor in the whole oxidation and spontaneous combustion stage, the inhibition rate E1 in the slow oxidation stage, the inhibition rate E2 in the accelerated oxidation stage and the inhibition rate E3 in the intense oxidation stage are calculated respectively.

[0011] The formula for calculating the inhibition rate is: E = (C1 - C2) / C1, where C1 is the total concentration of index gas released by the raw coal sample at different stages, and C2 is the total concentration of index gas released by the inhibited coal sample at different stages.

[0012] S4. Based on the volume fraction curves of CO, C2H4 and C2H2 drawn in step S2 above, draw the gas generation rate curve AT as a function of temperature, where the gas generation rate A is the rate at which the amount of gas produced changes with temperature.

[0013] S5. Combining the inhibition rate obtained in step S3 and the gas generation rate curve obtained in step S4, the inhibition law and inhibition effect of the inhibitor on the coal sample are obtained.

[0014] S6. Based on the CO inhibition curve plotted in step S2 above, plot a graph showing the relationship between the gas concentration ratio C2 / C1 before and after inhibition and time at different times throughout the entire spontaneous combustion cycle of the coal sample. Calculate the inhibition lifetime L based on the effective inhibition duration of the inhibitor. In the formula, L Represents the inhibition lifetime of the inhibitor, in minutes; t n The time when C2 / C1=0.6 occurs for the nth time, in minutes; t q The total duration of the entire experimental cycle is expressed in minutes; n is the nth intersection point of the CO inhibition curve and C2 / C1=0.6.

[0015] S7. Based on the inhibition rate curve obtained in step S3 and the inhibition lifetime obtained in step S4, and combined with the analysis of the inhibition effect and inhibition persistence of the inhibitor, the inhibition performance of the inhibitor on the coal sample in the whole stage of oxidation and spontaneous combustion is obtained.

[0016] In step S2, the temperature rise rate in the programmable temperature control chamber is set to 1℃ / min and the air flow rate is 100ml / min, and samples are taken every 10 minutes.

[0017] In step S3, the slow oxidation stage, accelerated oxidation stage, and intense oxidation stage are divided based on the temperature at which C2H4 and C2H2 appear. That is, the slow oxidation stage is before the appearance of C2H4, the accelerated oxidation stage is after the appearance of C2H4 and before the appearance of C2H2, and the intense oxidation stage is after the appearance of C2H2.

[0018] In step S4, the gas generation rate A is represented in the inhibition curve as the slope of each curve, i.e., C / T. The higher the gas generation rate, the weaker the inhibition effect of the inhibitor, and vice versa.

[0019] The beneficial effects of this invention are:

[0020] 1) This invention utilizes a programmable temperature-controlled chamber to heat raw coal samples and inhibited coal samples separately, simulating the process of coal oxidation and spontaneous combustion. Based on the concentrations of indicator gases CO, C2H4, and C2H2 generated before and after the addition of the inhibitor, and considering the variation patterns of these three indicator gases during the coal oxidation and spontaneous combustion process, as well as their advantages and disadvantages as indicator gases, combined with traditional experimental methods, the inhibition rate of the inhibitor is calculated in the entire oxidation and spontaneous combustion stage and in the sub-stages of oxidation and spontaneous combustion: slow oxidation stage, accelerated oxidation stage, and intense oxidation stage. The gas generation rate is introduced to describe the inhibition effect of the inhibitor in each sub-stage, thus obtaining the inhibition performance and inhibition law of the inhibitor in the entire oxidation and spontaneous combustion process. Among them, the inhibition rate in the entire oxidation and spontaneous combustion stage can be used to systematically compare the inhibition performance of different types of inhibitors, and the inhibition rate and gas generation rate in each oxidation and spontaneous combustion sub-stage can be used to study the inhibition mechanism and inhibition law of the inhibitor at different temperatures.

[0021] 2) This invention combines the full-stage inhibition rate and inhibition life, which can more comprehensively evaluate the inhibition effect of the inhibitor and improve the accuracy of the evaluation results. It can be widely used by technicians in the coal seam mining process to select the type and concentration of inhibitor.

[0022] 3) In this invention, inhibition lifetime is another indicator for determining the performance of inhibitors, reflecting the inhibitor's inhibition persistence. Since the time range of each oxidative spontaneous combustion stage is different, it is impossible to unify the standard if the inhibition lifetime is calculated using CO, C2H4 and C2H2 index gases respectively. Therefore, in combination with traditional testing methods, CO gas index is still used to calculate the inhibition lifetime. The inhibition rate and inhibition lifetime, two important indicators, are combined to evaluate the performance of inhibitors, providing more reference for operators to select and use inhibitors during coal seam mining. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the coal natural oxidation gas detection device of the present invention;

[0024] Figure 2 This is a graph showing the change in CO volume fraction in an embodiment of the present invention.

[0025] Figure 3 This is a graph showing the change in the volume fraction of C2H4 in an embodiment of the present invention.

[0026] Figure 4 This is a graph showing the change in C2H2 volume fraction in an embodiment of the present invention.

[0027] Figure 5 This is a graph showing the change in CO gas generation rate with temperature, plotted in an embodiment of the present invention.

[0028] Figure 6This is a graph showing the C2H4 gas generation rate as a function of temperature, plotted in an embodiment of the present invention.

[0029] Figure 7 This is a graph showing the C2H2 gas generation rate as a function of temperature, plotted in an embodiment of the present invention.

[0030] Figure 8 This is a graph showing the relationship between the ratio of CO gas concentration before and after inhibition and time at different times during the entire auto-ignition cycle, as illustrated in an embodiment of the present invention.

[0031] In the diagram, 1-air pump, 2-water and dust removal device, 3-inlet pipe, 4-pressure stabilizer, 5-gas flow meter, 6-gas preheater, 7-reaction tube, 8-programmable temperature control chamber, 9-condenser, 10-gas chromatograph, 11-computer, 12-printer. Detailed Implementation

[0032] The present invention will be further explained and described below with reference to the accompanying drawings and specific embodiments.

[0033] The raw coal samples and inhibited coal samples used in the experiment were prepared using the following methods:

[0034] (1) Collect coal samples according to regulations, process the collected coal samples by reduction, crushing and sieving to obtain experimental coal samples of 30 mesh to 45 mesh, bottle and seal for later use, and obtain raw coal samples for experiment.

[0035] (2) Prepare an aqueous solution of inhibitor with a mass concentration of 20%. Weigh 20±0.1g of inhibitor sample, put it into a 100ml beaker, add distilled water to dilute to the mark, stir thoroughly and set aside.

[0036] (3) Weigh 25±0.1g of raw coal sample and place it in a porcelain dish. Add an appropriate amount of inhibitor aqueous solution, stir evenly, and then place it in a vacuum drying oven to dry for 24 hours. Then take it out for use and obtain the experimental inhibitor coal sample.

[0037] Example: Figure 1-4 As shown, the present invention provides a test method for determining the performance indicators of inhibitors, comprising the following steps:

[0038] S1. Weigh the raw coal sample (25±0.1g) and the prepared inhibited coal sample into the reaction tube 7 respectively. Place the reaction tube 7 into the programmable temperature control box 8, connect the air pump 1, gas chromatograph 10 and computer 11, and check the airtightness of the device.

[0039] S2. Turn on the programmable temperature control chamber 8 and air pump 1, set the heating rate to 1℃ / min and the air flow rate to 100ml / min, and then take samples every 10 minutes; under normal pressure, raise the temperature from room temperature to 300℃, and use gas chromatograph 10 to record the volume concentrations of CO, C2H4, and C2H2 generated in the raw coal sample and the inhibited coal sample at different temperatures, respectively. Use computer 11 to plot the corresponding inhibition curves, such as... Figure 2 , 3 As shown in Figure 4.

[0040] from Figure 2 , Figure 3 , Figure 4 It can be seen that the inhibitor is effective in inhibiting the coal sample throughout the entire process. Figure 2 The initial generation temperature of CO gas in the coal sample from the Central Plains was 40℃, and its volume fraction increased approximately exponentially with increasing temperature, while the initial generation temperature of CO gas in the inhibited coal sample was 60℃, and the inhibition effect was obvious. Figure 3 The initial temperature of C2H4 gas in the medium-resisted coal sample increased by 20℃, and its production was significantly lower than that of CO. Figure 4 Acetylene gas also exhibits a similar pattern.

[0041] S3. Based on the volume fraction curves of CO, C2H4, and C2H2 as a function of temperature plotted in step S2 above, and combined with the formula for calculating the inhibition rate, the inhibition rate E of the inhibitor in the entire oxidation and spontaneous combustion stage, the inhibition rate E1 in the slow oxidation stage, the inhibition rate E2 in the accelerated oxidation stage, and the inhibition rate E3 in the intense oxidation stage are calculated respectively. The slow oxidation stage, the accelerated oxidation stage, and the intense oxidation stage are divided according to the temperature at which C2H4 and C2H2 appear. Among them, the temperature T ≤ 100℃ in the slow oxidation stage, the temperature 100℃ < T ≤ 200℃ in the accelerated oxidation stage, and the temperature T > 200℃ in the intense oxidation stage.

[0042] The formula for calculating the inhibition rate is: E = (C1 - C2) / C1, where C1 is the total concentration of index gas released by the raw coal sample at different stages, and C2 is the total concentration of index gas released by the inhibited coal sample at different stages.

[0043] Table 1 below shows the inhibition rate and total inhibition rate of the inhibitor at different oxidation stages.

[0044] Table 1

[0045]

[0046] Table 1 shows that the inhibition rate, whether calculated using only CO or three indicators (CO, C2H4, and C2H2), exhibits a trend of first increasing and then decreasing. This indicates that the inhibitor demonstrates better inhibition during the accelerated oxidation stage, while its inhibitory effect weakens during the vigorous oxidation stage. Furthermore, the inhibition rate results differ between the accelerated and vigorous oxidation stages due to the different indicator gases: the inhibition rate calculated using C2H4 as the indicator in the accelerated oxidation stage is 73.1%, while the inhibition rate calculated using C2H2 as the indicator in the vigorous oxidation stage is 65.4%. Both results are higher than the inhibition rate calculated using CO as the indicator, suggesting that considering the inhibition rate solely based on CO is somewhat one-sided. Additionally, the total inhibition rate reaches 64.6%, indicating that the inhibitor has a good inhibition effect.

[0047] S4. Based on the volume fraction curves of CO, C2H4 and C2H2 drawn in step S2 above, draw the gas generation rate curve AT as a function of temperature. The gas generation rate A is the rate at which the amount of gas produced changes with temperature. In the inhibition curve, the gas generation rate A is represented by the slope of each curve, i.e., C / T. The higher the gas generation rate, the weaker the inhibition effect of the inhibitor, and vice versa.

[0048] The curve of gas generation rate as a function of temperature is shown below. Figure 5 , Figure 6 , Figure 7 As shown in the figure, the C / T ratio of the inhibited coal sample was lower than that before inhibition throughout the entire oxidation process, and showed an approximately exponential upward trend. Figure 5 In the first half of the test, CO release was low before 100℃, and the two curves basically overlapped. Between 100℃ and 200℃, CO release increased significantly in both coal samples, but the growth trend of the inhibitory coal sample curve was slower, indicating that the inhibitor played a good inhibitory role in this stage. After 200℃, the trend of the two curves increased compared to before, indicating that although the inhibitor could still inhibit the spontaneous combustion of the coal sample, its inhibitory effect was significantly weakened.

[0049] Figure 6 In the range of 100℃-200℃, the growth trend of the two curves is relatively slow, and the amount of C2H4 released is small, indicating that the inhibitor has a significant inhibitory effect; after 200℃, the intense oxidation stage begins, the slope of the curve increases, and the inhibitory effect of the inhibitor weakens. Figure 7 In the study, the C2H2 release of both coal samples was much smaller than that of CO and C2H4, and the slope of the curve gradually increased, which also indicates that the inhibitory effect of the inhibitor weakened at this stage.

[0050] S5. Combining the inhibition rate obtained in step S3 and the gas generation rate curve obtained in step S4, the inhibition law and inhibition effect of the inhibitor on the coal sample are obtained.

[0051] S6. Based on the CO inhibition curve plotted in step S2 above, plot a graph showing the relationship between the gas concentration ratio C2 / C1 before and after inhibition and time at different times throughout the entire spontaneous combustion cycle of the coal sample. Calculate the inhibition lifetime L based on the effective inhibition duration of the inhibitor. In the formula, L Represents the inhibition lifetime of the inhibitor, in minutes; t n The time when C2 / C1=0.6 occurs for the nth time, in minutes; t q The total duration of the entire experimental cycle is expressed in minutes; n is the nth intersection point of the CO inhibition curve and C2 / C1=0.6.

[0052] like Figure 8 As shown, C2 / C1 < 0.6 during the experimental period, indicating that the inhibitor is effective in inhibiting the coal sample throughout the entire process, with an inhibition life of 300 min.

[0053] S7. Based on the inhibition rate curve obtained in step S3 and the inhibition lifetime obtained in step S4, and combined with the analysis of the inhibition effect and inhibition persistence of the inhibitor, the inhibition performance of the inhibitor on the coal sample in the whole stage of oxidation and spontaneous combustion is obtained.

[0054] Based on the above analysis, the inhibitor showed the best inhibition effect in the accelerated oxidation stage, followed by the slow oxidation stage, and significantly weakened in the vigorous oxidation stage, but the overall inhibition rate was still as high as 64.6%. Furthermore, the inhibitor's inhibitory effect on the coal sample was effective throughout the experimental period, with an inhibition lifespan of 300 minutes. In addition, the inhibitor effectively increased the initial formation temperature of CO, C2H4, and C2H2 during the coal spontaneous combustion oxidation process, and reduced the release of these gases, demonstrating excellent inhibition performance.

[0055] This invention comprehensively considers the variation patterns of CO, C2H4, and C2H2 gases during the coal oxidation and spontaneous combustion process, as well as their advantages and disadvantages as indicator gases. Combining traditional experimental methods, it calculates the inhibition rate of the inhibitor at different oxidation stages and introduces the gas generation rate to describe the inhibition effect of the inhibitor at each sub-stage. This yields the inhibition performance and inhibition pattern of the inhibitor throughout the entire oxidation and spontaneous combustion process, thereby improving the accuracy of the evaluation results.

[0056] The above description is only used to illustrate the technical solution of the present invention and is not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention, as long as they do not depart from the spirit and scope of the technical solution of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A test method for determining the performance indicators of inhibitors, characterized in that: Includes the following steps: S1. Weigh the raw coal sample and the prepared inhibited coal sample into the reaction tube respectively, put the reaction tube into the programmable temperature control box, connect the air pump, gas chromatograph and computer, and check the airtightness of the device. S2. Turn on the programmable temperature control chamber and air pump, and raise the temperature from room temperature to 300℃ under normal pressure. Use a gas chromatograph to record the volume concentrations of CO, C2H4 and C2H2 generated at different temperatures for the raw coal sample and the inhibited coal sample, and plot the corresponding inhibition curves. S3. Based on the volume fraction of CO, C2H4 and C2H2 as a function of temperature plotted in step S2 above, and combined with the formula for calculating the inhibition rate, the inhibition rate E of the inhibitor in the whole oxidation and spontaneous combustion stage, the inhibition rate E1 in the slow oxidation stage, the inhibition rate E2 in the accelerated oxidation stage and the inhibition rate E3 in the intense oxidation stage are calculated respectively. The formula for calculating the inhibition rate is: E=(C1-C2) / C1, where C1 is the total concentration of index gas released by the raw coal sample at different stages, and C2 is the total concentration of index gas released by the inhibited coal sample at different stages. Based on the temperature at which C2H4 and C2H2 appear, the oxidation stages are divided into slow oxidation, accelerated oxidation, and intense oxidation. That is, the slow oxidation stage occurs before the appearance of C2H4, the accelerated oxidation stage occurs between the appearance of C2H4 and the appearance of C2H2, and the intense oxidation stage occurs after the appearance of C2H2. S4. Based on the volume fraction curves of CO, C2H4 and C2H2 drawn in step S2 above, draw the gas generation rate curve AT as a function of temperature, where the gas generation rate A is the rate at which the amount of gas produced changes with temperature. S5. Combining the inhibition rate obtained in step S3 and the gas generation rate curve obtained in step S4, the inhibition law and inhibition effect of the inhibitor on the coal sample are obtained. S6. Based on the CO inhibition curve plotted in step S2 above, plot a graph showing the relationship between the gas concentration ratio C2 / C1 before and after inhibition and time at different times throughout the entire spontaneous combustion cycle of the coal sample. Calculate the inhibition lifetime L based on the effective inhibition duration of the inhibitor. In the formula, L represents the inhibition lifetime of the inhibitor, in minutes; t n The time when C2 / C1 = 0.6 occurs for the nth time, in minutes; t q The total duration of the entire experimental cycle is expressed in minutes; n is the nth intersection point of the CO inhibition curve and C2 / C1 = 0.

6. S7. Based on the inhibition rate curve obtained in step S3 and the inhibition lifetime obtained in step S4, and combined with the analysis of the inhibition effect and inhibition persistence of the inhibitor, the inhibition performance of the inhibitor on the coal sample in the whole stage of oxidation and spontaneous combustion is obtained.

2. The test method for determining the performance indicators of inhibitors according to claim 1, characterized in that: In step S2, the temperature rise rate in the programmable temperature control chamber is set to 1℃ / min and the air flow rate is 100ml / min, and samples are taken every 10 minutes.

3. The test method for determining the performance indicators of inhibitors according to claim 1, characterized in that: In step S4, the gas generation rate A is represented in the inhibition curve as the slope of each curve, i.e., C / T. The higher the gas generation rate, the weaker the inhibition effect of the inhibitor, and vice versa.

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