CN117214039A - Coking coal isothermal fluidity reaction kinetics analysis method - Google Patents
Coking coal isothermal fluidity reaction kinetics analysis method Download PDFInfo
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- 239000003245 coal Substances 0.000 title claims abstract description 201
- 238000004939 coking Methods 0.000 title claims abstract description 139
- 238000006243 chemical reaction Methods 0.000 title claims abstract description 33
- 238000004458 analytical method Methods 0.000 title claims abstract description 10
- 238000012360 testing method Methods 0.000 claims abstract description 45
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- 238000013213 extrapolation Methods 0.000 claims description 12
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- 238000002156 mixing Methods 0.000 claims description 6
- 238000011068 loading method Methods 0.000 claims description 4
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- 238000011156 evaluation Methods 0.000 description 2
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- 230000001133 acceleration Effects 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
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Abstract
The invention relates to a coking coal isothermal fluidity reaction kinetics analysis method, which comprises the following steps: 1) Isothermal fluidity test; 2) Isothermal fluidity curve treatment; 3) Determining the change rule of the isothermal fluidity characteristic parameter along with the temperature; 4) Predicting plastic characteristic parameters at other temperatures; according to the invention, by analyzing the isothermal fluidity curve of the coking coal, a reaction dynamics equation in a key temperature interval 400-440 ℃ of the coking coal is established, the quality of the coking coal is scientifically evaluated, and reaction dynamics parameters at other temperatures are predicted.
Description
Technical Field
The invention relates to the technical field of coking coal evaluation, in particular to a method for accurately evaluating the plastic reaction kinetics of coking coal by utilizing an isothermal flow curve.
Background
The fluidity of the coal characterizes the viscosity of the colloid formed by the coal during pyrolysis, is one of the plastic indexes of the coal, and the Ji-type fluidity index of the coal can reflect the quantity and the quality of the colloid at the same time. Fluidity is an effective means of studying the rheology and thermal decomposition kinetics of coal, and can be used for guiding coal blending and performing coke strength prediction. A commonly used fluidity measurement method is the Ji Zele plastometer method, proposed by German Ji Zele (K.Gieseler) in 1934. The Ji fluidity reflects the properties of the colloid generated by the heated coal, such as the quantity, the thermal stability, the viscosity, the fluidity, the volatile separation and the like of the colloid.
The Ji-type fluidity is mainly used for testing the fluidity and the colloid body temperature range of the colloid body, can reflect the quantity and the property of the colloid body at the same time, can better reflect the thermoplastic behavior of the colloid body of different coking coals in the coking process, has strong distinguishing capability and is sensitive to oxidation, thus being an important index for representing the quality of the coking coals. The Ji-style fluidity provides scientific basis for reasonably using coking coal, optimizing coal blending structure and accurately predicting coke quality.
The plastic temperature range of coking coal is concentrated and is generally between 380 and 450 ℃. Within the temperature range, the reaction dynamics of the coking coal has important significance for accurately evaluating the quality of the coking coal, predicting the coking behavior of the coking coal and controlling the quality of the coke.
Disclosure of Invention
The invention provides a coking coal isothermal fluidity reaction dynamics analysis method, and simultaneously establishes a reaction dynamics equation in a coking coal key temperature interval, so that the quality of the coking coal can be scientifically evaluated, and reaction dynamics parameters at other temperatures can be predicted.
In order to achieve the above purpose, the invention is realized by adopting the following technical scheme:
a coking coal isothermal fluidity reaction kinetics analysis method is characterized in that a reaction kinetics equation in a coking coal key temperature interval of 400-440 ℃ is established by analyzing an isothermal fluidity curve of coking coal, the quality of the coking coal is scientifically evaluated, and reaction kinetics parameters at other temperatures are predicted.
The coking coal isothermal fluidity reaction kinetics analysis method specifically comprises the following steps:
1) Isothermal fluidity test;
2) Isothermal fluidity curve treatment;
obtaining softening starting time, time for reaching maximum fluidity, curing time, and plastic time interval, namely time interval in plastic state, and maximum fluidity from isothermal fluidity curve; in the isothermal fluidity test process, the fluidity of coking coal is divided into three stages along with the time change, namely a melting stage, a maximum fluidity stage and a coking stage; respectively carrying out linear fitting on isothermal fluidity data of a melting stage and a coking stage to determine a melting slope and a coking slope; according to the extrapolation intersection point of the melting equation and the coking equation, calculating the maximum flow of the extrapolation;
3) Determining the change rule of the isothermal fluidity characteristic parameter along with the temperature;
according to isothermal fluidity test data of the coal sample in a temperature range of 400-440 ℃, calculating fluidity characteristic parameters at different temperatures respectively, and establishing a dynamic equation of isothermal fluidity characteristic parameters along with temperature change;
4) Predicting plastic characteristic parameters at other temperatures;
according to the dynamic equation of isothermal fluidity parameters, the melting interval slope, coking interval slope and extrapolated maximum fluidity all follow the Arrhenius equation, and the plasticity characteristics of the coking coal at other temperatures are calculated by interpolation or finite extrapolation in the coking coal plasticity temperature interval.
Further, in the step 1), the specific process of isothermal fluidity test is as follows:
crushing coking coal to a granularity smaller than 0.85mm, dividing the coking coal into coal samples by a bipartite, dividing the coal samples into multiple parts, taking 1 part of the coal samples, crushing the coal samples to a granularity smaller than 0.425mm by a progressive crushing method, and ensuring that the part of the coal samples with the granularity smaller than 0.2mm is not more than 50%; fully and uniformly mixing the coal samples, and taking the coal samples from different positions and loading the coal samples into a crucible of a Gibby plastometer;
the static load is pressed on the coal sample, and the dynamic load is freely dropped from a high place to strike the coal sample for multiple times, so that the coal sample is changed into a molding state from a loose state; a stirring paddle is arranged in the crucible, and a constant moment is applied to a stirring paddle shaft; lowering the plastic instrument head to the bottom of the crucible, and immersing the plastic instrument head into a molten solder bath with the temperature in a plastic temperature range;
the experimental temperature is 400-440 ℃, the coal sample is heated to the set temperature and kept constant in temperature, isothermal fluidity test is carried out, and a relation curve of fluidity changing with time is established.
Further, the temperature fluctuation in the isothermal fluidity test process is less than or equal to 0.1 ℃/min; the temperature of the molten solder bath was returned to the initial temperature within 10.+ -. 2 minutes of immersing the crucible in the molten solder bath.
Compared with the prior art, the invention has the beneficial effects that:
1) By analyzing the isothermal fluidity curve of the coking coal, a reaction kinetic equation in a key temperature interval of the coking coal is established, the quality of the coking coal is scientifically evaluated, and the reaction kinetic parameters at other temperatures can be predicted;
2) The analysis method disclosed by the invention is simple to operate and easy to realize, and has important significance in scientific evaluation of coking coal and reduction of raw material purchasing cost for coking enterprises.
Drawings
FIG. 1 is a typical isothermal fluidity curve;
FIG. 2 is a schematic diagram of isothermal fluidity profile processing;
FIG. 3 is an isothermal fluidity curve (420 ℃) for coal sample 1;
FIG. 4 is an isothermal fluidity profile treatment (420 ℃) for coal sample 1;
FIG. 5 is an isothermal fluidity curve (420 ℃) for coal sample 2;
FIG. 6 is an isothermal fluidity profile treatment (420 ℃) for coal sample 2;
FIG. 7 is an isothermal fluidity curve (420 ℃) for coal sample 3;
FIG. 8 is an isothermal fluidity profile treatment (420 ℃) for coal sample 3;
FIG. 9 is an isothermal fluidity curve (420 ℃) for coal sample 4;
FIG. 10 is an isothermal fluidity profile treatment (420 ℃) for coal sample 4;
FIG. 11 is an isothermal fluidity curve (420 ℃) for coal sample 5;
FIG. 12 is an isothermal fluidity profile treatment (420 ℃) for coal sample 5;
FIG. 13 is an isothermal fluidity curve (420 ℃) for coal sample 6;
FIG. 14 is an isothermal fluidity profile treatment (420 ℃) for coal sample 6;
FIG. 15 is an isothermal fluidity curve (420 ℃) for coal sample 7;
FIG. 16 is an isothermal flow graph treatment (420 ℃) for coal sample 7;
FIG. 17 is an isothermal fluidity curve (420 ℃) for coal sample 8;
FIG. 18 is an isothermal fluidity profile treatment (420 ℃) for coal sample 8;
FIG. 19 is an isothermal fluidity curve (420 ℃) for coal sample 9;
FIG. 20 is an isothermal fluidity profile treatment (420 ℃) for coal sample 9;
FIG. 21 is an isothermal fluidity curve (420 ℃) for coal sample 10;
FIG. 22 is an isothermal fluidity profile treatment (420 ℃) for coal sample 10;
FIG. 23 is an isothermal fluidity curve (420 ℃) for coal sample 11;
FIG. 24 is an isothermal fluidity profile treatment (420 ℃) for coal sample 11;
FIG. 25 is an isothermal fluidity curve (420 ℃) for coal sample 12;
FIG. 26 is an isothermal fluidity profile treatment (420 ℃) for coal sample 12;
FIG. 27 is an isothermal fluidity curve (420 ℃) for coal sample 13;
FIG. 28 is an isothermal fluidity profile treatment (420 ℃) for coal sample 13;
FIG. 29 is an isothermal fluidity curve (420 ℃) for coal sample 14;
FIG. 30 is an isothermal fluidity profile treatment (420 ℃) for coal sample 14;
FIG. 31 is an isothermal fluidity curve (420 ℃) for coal sample 15;
FIG. 32 is an isothermal fluidity profile treatment (420 ℃) for coal sample 15;
FIG. 33a is a graph showing a first law of change of a melting slope (mering slope) of a coal sample 8 with temperature;
FIG. 33b is a second law of variation of melting slope (mering slope) of coal sample 8 with temperature;
FIG. 34 is a graph showing the change of coking slope (coking slope) of the coal sample 8 with temperature;
FIG. 35 is a graph showing the variation law of the maximum fluidity [ ln (MF) ] of the coal sample 8 with temperature;
FIG. 36 is a graph showing the law of extrapolated maximum fluidity [ ln (MFc) ] of coal sample 8 as a function of temperature;
FIG. 37 is a plot of melting slope [ ln (km) ] versus temperature (1/T) for experimental coal samples;
FIG. 38 is a graph showing the relationship between coking slope [ ln (kc) ] and temperature (1/T) of experimental coal samples;
FIG. 39 is a graph showing the relationship between the maximum fluidity [ ln (lnmF) ] of an experimental coal sample and the temperature (1/T);
FIG. 40 is a graph showing the relationship between extrapolated maximum fluidity [ ln (lnmFc) ] of experimental coal samples and temperature (1/T).
Detailed Description
According to the method for analyzing isothermal fluidity reaction kinetics of coking coal, disclosed by the invention, a reaction kinetics equation in a key temperature interval of 400-440 ℃ of the coking coal is established by analyzing an isothermal fluidity curve of the coking coal, the quality of the coking coal is scientifically evaluated, and reaction kinetics parameters at other temperatures are predicted.
The invention relates to a coking coal isothermal fluidity reaction kinetics analysis method, which specifically comprises the following steps:
1) Isothermal fluidity test;
2) Isothermal fluidity curve treatment;
obtaining softening starting time, time for reaching maximum fluidity, curing time, and plastic time interval, namely time interval in plastic state, and maximum fluidity from isothermal fluidity curve; in the isothermal fluidity test process, the fluidity of coking coal is divided into three stages along with the time change, namely a melting stage, a maximum fluidity stage and a coking stage; respectively carrying out linear fitting on isothermal fluidity data of a melting stage and a coking stage to determine a melting slope and a coking slope; according to the extrapolation intersection point of the melting equation and the coking equation, calculating the maximum flow of the extrapolation;
3) Determining the change rule of the isothermal fluidity characteristic parameter along with the temperature;
according to isothermal fluidity test data of the coal sample in a temperature range of 400-440 ℃, calculating fluidity characteristic parameters at different temperatures respectively, and establishing a dynamic equation of isothermal fluidity characteristic parameters along with temperature change;
4) Predicting plastic characteristic parameters at other temperatures;
according to the dynamic equation of isothermal fluidity parameters, the melting interval slope, coking interval slope and extrapolated maximum fluidity all follow the Arrhenius equation, and the plasticity characteristics of the coking coal at other temperatures are calculated by interpolation or finite extrapolation in the coking coal plasticity temperature interval.
Further, in the step 1), the specific process of isothermal fluidity test is as follows:
crushing coking coal to a granularity smaller than 0.85mm, dividing the coking coal into coal samples by a bipartite, dividing the coal samples into multiple parts, taking 1 part of the coal samples, crushing the coal samples to a granularity smaller than 0.425mm by a progressive crushing method, and ensuring that the part of the coal samples with the granularity smaller than 0.2mm is not more than 50%; fully and uniformly mixing the coal samples, and taking the coal samples from different positions and loading the coal samples into a crucible of a Gibby plastometer;
the static load is pressed on the coal sample, and the dynamic load is freely dropped from a high place to strike the coal sample for multiple times, so that the coal sample is changed into a molding state from a loose state; a stirring paddle is arranged in the crucible, and a constant moment is applied to a stirring paddle shaft; lowering the plastic instrument head to the bottom of the crucible, and immersing the plastic instrument head into a molten solder bath with the temperature in a plastic temperature range;
the experimental temperature is 400-440 ℃, the coal sample is heated to the set temperature and kept constant in temperature, isothermal fluidity test is carried out, and a relation curve of fluidity changing with time is established.
Further, the temperature fluctuation in the isothermal fluidity test process is less than or equal to 0.1 ℃/min; the temperature of the molten solder bath was returned to the initial temperature within 10.+ -. 2 minutes of immersing the crucible in the molten solder bath.
The following is a further description of embodiments of the invention, taken in conjunction with the accompanying drawings:
the plastic temperature range of coking coal is concentrated and is generally between 380 and 450 ℃. Within the temperature range, the reaction dynamics of the coking coal has important significance for accurately evaluating the quality of the coking coal, predicting the coking behavior of the coking coal and controlling the quality of the coke.
The invention aims to provide an analysis method for isothermal fluidity of coking coal, and simultaneously, a reaction dynamics equation in a key temperature interval of the coking coal is established, so that the quality of the coking coal can be scientifically evaluated, and reaction dynamics parameters at other temperatures can be predicted.
In order to achieve the aim of the invention, the invention adopts the following technical scheme:
1. isothermal fluidity test
Crushing coking coal to a granularity of less than 0.85mm, dividing the coking coal into coal samples (such as 500 g) by a bipartite, dividing the coal samples into multiple parts (such as 4 parts), taking 1 part of the coking coal, crushing the coking coal to the granularity of less than 0.425mm by a step-by-step crushing method, and ensuring that the part of the coal samples with the granularity of less than 0.2mm is not more than 50%. Fully and uniformly mixing the coal samples, and taking the coal samples (such as 5 g) from different positions and loading the coal samples into a crucible of a Gibby plastometer; and when the sample is filled, the stirring paddle is rotated, so that the coal sample is filled in a gap below the stirring arm.
The coal sample is pressed by static load (for example, the weight is 9 kg), and is hit by dynamic load (for example, the weight is 1 kg) from high (for example, the height is 115 mm) for multiple times (for example, 12 times), so that the coal sample is changed into a forming state from a loose state.
The middle part of the crucible is vertically provided with a stirring paddle, and a constant moment is applied to a stirring paddle shaft, such as 101.6+/-5.lgcm [ (9.96+/-0.05) ×10 ] -3 N·m]. The plastic head was lowered to the bottom of the crucible, immersed 75mm into the molten solder bath at a plastic temperature interval, and a thermocouple was inserted into the molten solder bath.
The experimental temperature is a certain temperature between 400 and 440 ℃. And (3) quickly heating the coal sample to a set temperature, keeping the temperature constant, carrying out isothermal fluidity test, and establishing a relation curve of fluidity changing along with time.
The temperature fluctuation is ensured to be less than or equal to 0.1 ℃/min in the test process. The thermocouple is controlled to heat, so that the crucible is immersed in the molten solder bath for 10+/-2 minutes, and the temperature of the molten solder bath is restored to the initial temperature.
2. Isothermal fluidity curve processing
In the plastic change stage of coking coal, two reactions with opposite effects of cracking reaction and condensation reaction exist at the same time. A typical isothermal fluidity profile is shown in figure 1. As can be seen from fig. 1, in the isothermal fluidity test process, the fluidity starts to increase slowly, then the fluidity increases in an inverted U-shape, and then decreases in an acceleration manner after reaching the maximum value; the fluidity was then slowly reduced to 1ddpm over time and the test ended.
Parameters such as the onset of softening time (ts), the time to reach maximum fluidity (tmax), the curing time (tr), the plastic time interval (time interval in plastic state Δt=tr-ts), and the Maximum Fluidity (MF) can be obtained from the isothermal fluidity curve.
In the isothermal fluidity test process, the change rule of the fluidity of coking coal with time can be divided into the following three stages (as shown in fig. 2):
(1) Melting: the fluidity increases with time, which is the melting stage of coking coal;
(2) Maximum flow stage: the fluidity of the high-volatile coking coal is high and basically kept stable within a certain time range. This stage varies from coal type to coal type and may not be present for some coking coals with a maximum fluidity of less than 10000 ddpm.
(3) Coking stage: the fluidity of the coking coal is further prolonged and reduced with time, and the coking stage of the coking coal is the stage of coking.
In the isothermal fluidity test process, the fluidity (lnMF) of the melting stage and the coking stage is substantially linear with time in the isothermal fluidity curve of most coking coals. In the initial stage of isothermal fluidity test, the fluctuation of the test data is relatively large, so that the fluctuating data points need to be removed; the invention respectively carries out linear fitting on isothermal fluidity data of a melting stage and a coking stage to determine a melting slope (km) and a coking slope (kc). The units of the melting slope and the coking slope are min -1 。
For the isothermal fluidity curve shown in FIG. 2, the fit of the melting interval equation in 5-12 min is:
ln(MF)＝1.315t-5.956R 2 = 0.9912 … … (1)
Fitting the coking interval equation within 17-25 min is as follows:
ln(MF)＝-1.071t+27.194R 2 = 0.9943 … … (2)
Wherein: ln (MF) is isothermal fluidity, ddpm; t is the reaction time, min; r is R 2 Is a correlation coefficient.
Maximum fluidity 19030ddpm occurs when the test time is 13 min; and in the period of 12-17 min, the fluidity is too high, and the measured value fluctuates due to gas precipitation. The extrapolated maximum fluidity [ ln (MFc) ] can be calculated from the extrapolated intersection of the melting equation and the coking equation. The extrapolated maximum fluidity (MFc) at 13.89min is 10431ddpm.
For coking coal with high volatile matter and high fluidity, the separation of volatile matter during pyrolysis can interfere with the test of the maximum fluidity, and the accuracy of the test result and the repeatability of the test are affected. The invention adopts curve extrapolation to obtain extrapolated maximum fluidity, is not interfered by precipitation of volatile substances, has strong test repeatability compared with the maximum fluidity obtained by test, and is a more stable measurement index.
3. Law of variation of isothermal fluidity characteristic parameter with temperature
According to isothermal fluidity test data of the coal sample within the range of 400-440 ℃, fluidity characteristic parameters at different temperatures are calculated respectively, and a dynamics equation of the isothermal fluidity characteristic parameters along with temperature change is established.
4. Prediction of plastic characteristic parameters at other temperatures
In the isothermal fluidity test, the time required for the mobility of the coking coal to increase from 1ddpm to the extrapolated maximum mobility is defined as tm, the time required for the mobility of the coking coal to decrease from the extrapolated maximum mobility to 1ddpm is defined as tc, and the isothermal fluidity interval range is tf:
km= [ ln (MFc) -ln1]/tm … … (3)
kc= [ ln (MFc) -ln1]/tc … … type (4)
tf=tm+tc=ln (MFc) × (1/m+1/c) … … (5)
Wherein: km-melting section slope; kc-coking zone slope; km, kc and ln (MF) were all experimentally obtained.
The linear relation between the melting slope [ ln (km) ], the coking slope [ ln (kc) ], the maximum fluidity [ ln (lnmfl) ] and the extrapolated maximum fluidity [ ln (lnMFc) ] and the temperature (1/T) is good, and the linear relation can be used as the basis of plastic characteristic calculation in the coking coal isothermal fluidity test process.
According to the dynamic equation of isothermal fluidity parameters, the melting interval slope (km), coking interval slope (kc) and extrapolated maximum fluidity [ ln (MFc) ] all follow the Arrhenius equation, so that the plastic characteristics of the coking coal at other temperatures can be conveniently calculated by interpolation or limited extrapolation in the plastic temperature interval of the coking coal.
The following examples are given by way of illustration of detailed embodiments and specific procedures based on the technical scheme of the present invention, but the scope of the present invention is not limited to the following examples.
[ example 1]
In this example, 15 kinds of coal samples were subjected to isothermal fluidity test at 420℃respectively, and isothermal fluidity curves and treatment results are shown in FIGS. 3 to 32.
From the graph, the isothermal fluidity curves of coking coals have similarity. The isothermal fluidity profile is asymmetric, and the development rate of the melting phase is slower than that of the coking phase. Generally, the lower the isothermal maximum fluidity, the lower the rate of development of the melting and coking stages.
Isothermal fluidity data of the coking coal with low fluidity are low, and fluctuation of the data is relatively large, so that errors are easy to introduce in the data processing process; isothermal fluidity data normalization of medium-fluidity coking coals is excellent, while isothermal fluidity curves of high-fluidity coking coals have similarity.
In this example, the fixed reaction temperatures were 400 ℃, 420 ℃ and 440 ℃, respectively, at which temperature isothermal fluidity tests were performed on 15 coking coal samples, respectively, to obtain maximum fluidity data, fit the melting slope and coking slope, and calculate the extrapolated maximum fluidity.
Melting slope of coal sample [ ln (k) m )]The relationship with the temperature (1/T) is shown in FIGS. 33a and 33 b. From the two graphs, the melting slope [ ln (k) m )]The linear relation with the temperature (1/T) is better. The isothermal melting slope is related to the maximum fluidity of the standard fluidity test, and has similarity when MF < 10000ddpm (coal 1-10). When MF is more than 10000ddpm (coal sample 11-15), the isothermal fluidity melting slope curve has similarity, and the variation amplitude is far greater than that of the coal samples 1-10.
Coking slope of coal sample [ ln (k) c )]The relationship with temperature (1/T) is shown in FIG. 34. From FIG. 34, it can be seen that the coking gradient [ ln (k) c )]The linear relation with the temperature (1/T) is better. The coking slope curves of the coal samples have similarity, and only the coal sample 1 has low fluidity, so that certain deviation of the coking slope curves occurs.
Maximum fluidity of coal sample [ ln (lnMF)]The relationship with temperature (1/T) is shown in FIG. 35. Extrapolated maximum fluidity of coal sample [ ln (lnMF) c )]The relationship with temperature (1/T) is shown in FIG. 36. From FIGS. 35 and 36, it can be seen that extrapolated maximum fluidity slope is similar to the law of variation of maximum fluidity slope with temperature, and that the maximum fluidity of the coal sample [ ln (lnMF)]And extrapolating the maximum fluidity [ ln (lnMF) c )]The linear relation with the temperature (1/T) is better. The maximum fluidity slope curve of the coal sample 1 is the lowest; maximum fluidity slope curves of coal sample 2, coal sample 3 and coal sample 4 are similar andthe distribution is concentrated; the maximum fluidity slope curves of the coal samples 5 to 10 are similar and the distribution is centralized; the maximum fluidity slope curves of the coal samples 11 to 15 are higher, the curves are similar, and the distribution is more concentrated.
[ example 2 ]
In this example, a typical medium-fluidity coking coal (coal sample 8) was subjected to 20 isothermal fluidity tests at different temperatures in its plastic zone (400-440 ℃ C.), and the fitted slope [ ln (km) of the melting zone at different temperatures was calculated]Fitting slope of coking zone [ ln (kc)]Maximum fluidity tested [ ln (MF)]And extrapolated calculated maximum fluidity [ ln (MFc)]And establishes a fit slope [ ln (k) m )]The law of change with temperature is shown in fig. 37.
Establishing a fit slope [ ln (k) for the coking zone c )]The law of change with temperature is shown in fig. 38.
The maximum fluidity [ ln (MF) ] of the test is a law of variation with temperature, as shown in fig. 39.
Extrapolation of the calculated maximum fluidity ln (MF c )]The law of change with temperature is shown in fig. 40.
Assuming that the reaction rate (k) of the coking coal complies with the Arrhenius equation:
k=a×exp (-Ea/RT) … … type (6)
Wherein: r-ideal gas constant, T-temperature, A-factor (a pre-exponential constant), ea-activation energy (activation energy).
Fitting slope [ ln (k) of coal sample 8 melting zone m )]Fitting slope of coking interval [ ln (k) c )]Maximum fluidity tested [ ln (MF)]And extrapolated calculated maximum fluidity ln (MF c )]All in linear relation to 1/T. The regression equation of isothermal fluidity parameters and 1/T of the coal sample 8 is shown in Table 1, and the linear correlation coefficient of the regression equation is extremely high. This shows that the melting slope, coking slope, maximum fluidity and extrapolated maximum fluidity all have a linear relationship with 1/T over a wide temperature range during isothermal fluidity testing, and are temperature dependent. I.e. the parameters all follow the Arrhenius equation。
TABLE 1 regression equation for isothermal fluidity parameters of coal sample 8 and 1/T
| Index (I) | Regression equation | Correlation coefficient R 2 |
| Melting slope | ln(k m )＝-22464×1/T+31.92 | 0.96126 |
| Coking slope | ln(k c )＝-26127×1/T+36.85 | 0.94926 |
| Maximum fluidity | ln(MF)＝-60286×1/T+92.15 | 0.95115 |
| Extrapolated maximum fluidity | ln(MF c )＝-60851×1/T+93.50 | 0.95656 |
The isothermal fluidity curve of coking coal varies with the constant temperature, but has a similar variation law.
[ example 3 ]
The linear relation between the melting slope [ ln (km) ], the coking slope [ ln (kc) ], the maximum fluidity [ ln (lnmfl) ] and the extrapolated maximum fluidity [ ln (lnMFc) ] and the temperature (1/T) is good, and the linear relation can be used as the basis of plastic characteristic calculation in the coking coal isothermal fluidity test process.
In this example, according to the isothermal rate equation established in example 1, isothermal fluidity data of 15 kinds of coking coals were all interpolated to 410 ℃, and melting slope, coking slope, maximum fluidity, extrapolated maximum fluidity, and isothermal fluidity intervals at the temperatures were calculated, respectively, as shown in table 2.
TABLE 2 calculation of isothermal flowability parameters (410 ℃ C.)
[ example 4 ]
This example extrapolates isothermal fluidity data for 15 coking coals to 390 ℃ according to the isothermal rate equation established in example 1, and calculates melting slope, coking slope, maximum fluidity, extrapolated maximum fluidity, and isothermal fluidity interval at that temperature, respectively, as shown in table 3.
TABLE 3 calculation of isothermal flowability parameters (390 ℃ C.)
The foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical scheme of the present invention and the inventive concept thereof, and should be covered by the scope of the present invention.
Claims (4)
1. A coking coal isothermal fluidity reaction kinetics analysis method is characterized in that a reaction kinetics equation in a coking coal key temperature interval of 400-440 ℃ is established by analyzing an isothermal fluidity curve of the coking coal, the quality of the coking coal is scientifically evaluated, and reaction kinetics parameters at other temperatures are predicted.
2. The method for analyzing isothermal fluidity reaction kinetics of coking coal according to claim 1, which is characterized by comprising the following steps:
1) Isothermal fluidity test;
2) Isothermal fluidity curve treatment;
obtaining softening starting time, time for reaching maximum fluidity, curing time, and plastic time interval, namely time interval in plastic state, and maximum fluidity from isothermal fluidity curve; in the isothermal fluidity test process, the fluidity of coking coal is divided into three stages along with the time change, namely a melting stage, a maximum fluidity stage and a coking stage; respectively carrying out linear fitting on isothermal fluidity data of a melting stage and a coking stage to determine a melting slope and a coking slope; according to the extrapolation intersection point of the melting equation and the coking equation, calculating the maximum flow of the extrapolation;
3) Determining the change rule of the isothermal fluidity characteristic parameter along with the temperature;
according to isothermal fluidity test data of the coal sample in a temperature range of 400-440 ℃, calculating fluidity characteristic parameters at different temperatures respectively, and establishing a dynamic equation of isothermal fluidity characteristic parameters along with temperature change;
4) Predicting plastic characteristic parameters at other temperatures;
according to the dynamic equation of isothermal fluidity parameters, the melting interval slope, coking interval slope and extrapolated maximum fluidity all follow the Arrhenius equation, and the plasticity characteristics of the coking coal at other temperatures are calculated by interpolation or finite extrapolation in the coking coal plasticity temperature interval.
3. The method for analyzing isothermal fluidity reaction kinetics of coking coal according to claim 2, wherein in the step 1), the specific process of isothermal fluidity test is as follows:
crushing coking coal to a granularity smaller than 0.85mm, dividing the coking coal into coal samples by a bipartite, dividing the coal samples into multiple parts, taking 1 part of the coal samples, crushing the coal samples to a granularity smaller than 0.425mm by a progressive crushing method, and ensuring that the part of the coal samples with the granularity smaller than 0.2mm is not more than 50%; fully and uniformly mixing the coal samples, and taking the coal samples from different positions and loading the coal samples into a crucible of a Gibby plastometer;
the static load is pressed on the coal sample, and the dynamic load is freely dropped from a high place to strike the coal sample for multiple times, so that the coal sample is changed into a molding state from a loose state; a stirring paddle is arranged in the crucible, and a constant moment is applied to a stirring paddle shaft; lowering the plastic instrument head to the bottom of the crucible, and immersing the plastic instrument head into a molten solder bath with the temperature in a plastic temperature range;
the experimental temperature is 400-440 ℃, the coal sample is heated to the set temperature and kept constant in temperature, isothermal fluidity test is carried out, and a relation curve of fluidity changing with time is established.
4. The method for analyzing isothermal fluidity reaction kinetics of coking coal according to claim 3, wherein the temperature fluctuation in the isothermal fluidity test process is less than or equal to 0.1 ℃/min; the temperature of the molten solder bath was returned to the initial temperature within 10.+ -. 2 minutes of immersing the crucible in the molten solder bath.
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