CN104142282A - Method for analyzing on-fire activation energy of spontaneous combustion characteristic of low-coalification-degree coal - Google Patents
Method for analyzing on-fire activation energy of spontaneous combustion characteristic of low-coalification-degree coal Download PDFInfo
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Abstract
The invention relates to a method for analyzing on-fire activation energy of the spontaneous combustion characteristic of low-coalification-degree coal. A thermogravimetric experiment method is used for analyzing the on-fire activation energy of the spontaneous combustion characteristic of the low-coalification-degree coal, and the volatile component yield is considered in the thermogravimetric analysis method, so that an analysis result accurately reflects the spontaneous combustion difficulty level of the low-coalification-degree coal.
Description
Technical field
The present invention relates to a kind of ignition activation energy analytical approach of low degree of coalification coal spontaneous combustion characteristic, be specifically related to the ignition activation energy computing method that a kind of low degree of coalification coal spontaneous combustion difficulty or ease based on thermogravimetric experiment are judged, be mainly used in using thermogravimetric experimental technique to analyze coal spontaneous combustion complexity.
Background technology
Coal spontaneous combustion disaster is one of the major casualty in colliery, and spontaneous combustion of coal has not only burnt valuable resource, produces a large amount of CO, CO
2and SO
2deng toxic and harmful, harm workman's health and lives, contaminated environment; Can also bring out the generation of gas, dust explosion accident, be the disaster that hinders Safety of Coal Mine Production.The more coal ignitability's authentication method of domestic and international application mainly contains Ovshinsky method, kindling point method, point of crossing temperature method, differential calorimetry, static state and dynamic oxygen adsorption method etc.From 20 century 70s, Chinese scholars generally adopts thermogravimetric analysis (TGA, Thermo Gravimetric Analysis) method is judged the characteristics such as catching fire, surely firing of coal and after-flame, by the coal combustion reaction kinetics equation of setting up, determine its kinetic parameter (reaction activity E, frequency factor and order of reaction n), and proposed the flammable discriminant index of coal, the steady index system such as combustion property discriminant index and burnout characteristic index according to kinetic parameter system.The method has feature simply, easily and fast, has obtained at present application comparatively widely.
Coal sample thermogravimetric analysis experiment judges that the Method And Principle of coal spontaneous combustion is, the TGA curve that oxidation obtains according to temperature programme Coal Under, and can there is obvious physical and chemical adsorption with oxygen in the coal sample that spontaneous combustion tendency is higher, produce the increase of quality before violent burning.At complete TGA curve, obvious 3 stages be should there are, dehydration zero-g period, oxidation weight gain stage and burning weight loss are respectively.The dehydration zero-g period be mainly under Elevated Temperature Conditions in coal moisture content constantly separate out, coal sample quality continuous decrease; The oxidation weight gain stage is mainly that coal continues to increase the quality of coal sample to the physical and chemical adsorption of oxygen; The burning weight loss stage is mainly that violent combustion reaction occurs, and produces a large amount of combustion gas products, and coal sample quality reduces rapidly.Above 3 stages can be applied respectively Arrhenius (Arrhenius) formula and obtain corresponding energy of activation, are defined as respectively dehydration energy of activation, ignition activation energy and combustive activation energy.
Computation process is the energy of activation application TGA experimental data in each stage, according to the order of reaction of oxidation of coal, determines the mechanism function of reaction.Take burning of coal reaction as first order reaction be example, set reaction model and be
（1）
Wherein: x is reaction conversion ratio,
, W
1and W
2the weight (weight percent is used in thermogravimetric experiment) of time point at the whole story is reacted in representative respectively.Substitution Arrhenius formula, owing to cannot obtaining analytic solution, adopts Coats-Redfen integral formula, asks approximate solution:
（2）
In formula: x is oxidation of coal hypergolic reaction conversion ratio, %; E, energy of activation KJ/mol; R, gas law constant, KJ/molK; A, pre-exponential factor, S
-1; T, temperature of reaction, K.
Design temperature T and time S have linear relationship simultaneously:
（3）
In formula:
for heating rate, K/s.
Because E value is very large, therefore 2RT/E item can be approximately equal to 0.According to chemical reaction progression, above formula left end
to inverse temperature 1/T mapping, if reaction functions is selected correctly should obtain straight line, according to the slope of straight line, can obtain activation energy.The energy of activation in oxidation weight gain stage is defined as ignition activation energy, and the size of energy of activation can reflect the complexity that chemical reaction carries out.Chemical reaction energy of activation is larger, shows to activate the required energy of common molecule larger, chemical reaction occurs more difficult; Energy of activation is less, and the required energy of activated molecule is less, and chemical reaction more easily occurs.Ignition activation energy can reflect the degree of coal spontaneous combustion difficulty or ease.
From above rule, can draw, the coal sample of easier spontaneous combustion is more obviously in the oxidation weight gain stage of thermogravimetric experiment weightening finish phenomenon, otherwise is more not easy spontaneous combustion.But because coal itself is a complicated potpourri, after the TGA experiment through a large amount of coal samples, find, the lower coal sample of some metamorphic grade i.e. low degree of coalification coal, in whole experimentation, all there is not the phenomenon of oxidation weight gain, from experimental result, show as intuitively it and oxygen binding ability is poor, show that it is for spontaneous combustion coal not.The result of calculating energy of activation also shows its ignition activation energy or spontaneous combustion coal not very greatly; Or the very little reaction rate that belongs to cannot be surveyed type very soon again, does not all conform to the actual conditions.
In view of this, need to invent the ignition activation energy analytical approach that the actual ignition quality of a kind of and low degree of coalification coal is close.
Summary of the invention
The object of the invention is to overcome the defect of prior art, a kind of ignition activation energy analytical approach of low degree of coalification coal spontaneous combustion characteristic is provided, the method step is simple, and analysis result can accurately reflect the spontaneous combustion complexity of low degree of coalification coal.
For achieving the above object, the technical solution used in the present invention is:
An ignition activation energy analytical approach for low degree of coalification coal spontaneous combustion characteristic, it specifically comprises the steps:
Step 1: utilize thermogravimetric experimental technique to test and draw thermogravimetric curve and dehydration end point temperature, ignition temperature coal sample;
Step 2: utilize thermogravimetric experimental facilities to carry out technical analysis experiment to coal sample, obtain dehydration end point to the volatile producibility variation with temperature rule within the scope of ignition temperature, obtain the massfraction △ W of relevant temperature output volatile matter;
Step 3: the massfraction that starts each corresponding temperature coal sample from dehydration end point is added to the massfraction △ W of relevant temperature output volatile matter, recycling new reaction conversion ratio
computing formula (4) is calculated reaction conversion ratio:
（4）；
In formula: W
end-volatile producibility while being ignition temperature, %;
The massfraction of corresponding institute output volatile matter during △ W-different temperatures, %;
To in the improved Coats-Redfen integral formula of △ x substitution (5) obtaining, obtain activation energy,
（5）；
In formula: △ x-reaction conversion ratio, %;
E-energy of activation KJ/mol;
R-gas law constant, KJ/molK;
A-pre-exponential factor, s
-1;
T-temperature of reaction, K.
Further, described step 2 concrete grammar is: utilize thermogravimetric experimental facilities, in only by N2 situation, coal sample is carried out to technical analysis, obtain volatile producibility, and matching volatile producibility dehydration end point in ignition temperature interval with the relation of temperature, calculate △ w.
Compared with prior art, the beneficial effect that the present invention obtains is:
The present invention is by considering volatile producibility in gravitational thermal analysis method, by utilizing the low degree of coalification coal spontaneous combustion of improved ignition activation energy methods analyst characteristic, direct effect is to make the method can adapt to the coal of different rank, long-range benefit has been to enrich the decision method of coal spontaneous combustion characteristic, to disclosing with prevention coal spontaneous combustion disaster mechanism, plays an important role.The present invention has Social benefit and economic benefit widely.
Accompanying drawing explanation
Fig. 1 is the TGA curve of low metamorphic grade coal sample;
Fig. 2 is Arrhenius calculated curve and the fitting a straight line of coal sample after improving one's methods.
Embodiment
Below in conjunction with specific embodiment, the present invention is described in more detail.
Embodiment 1
Ignition activation energy analytical approach to low metamorphic grade coal sample ignition quality, specifically comprises the steps:
Step 1: utilize thermogravimetric experimental technique to test and draw thermogravimetric curve and dehydration end point temperature, ignition temperature coal sample.Low metamorphic grade coal sample is chosen in test, on the comprehensive thermogravimetric analyzer of STA449C type TG/DAT, coal sample is carried out to thermogravimetric analysis.Test condition is: coal sample granularity < 0.297mm, heating rate 0.083K/s, the N that reacting gas is 40ml/min
2o with 10mL/min
2mixed gas, test findings is as shown in Figure 1.126 ℃ of dehydration end point temperature, 276 ℃ of ignition temperatures, 25～126 ℃ is the dehydration zero-g period, and 126～276 ℃ is to change oxidation " weightening finish " stage comparatively slowly, and 276 ℃ is the ignition stage later.
Step 2: utilize thermogravimetric experimental facilities to carry out technical analysis experiment to coal sample, mainly obtain dehydration end point to the volatile producibility variation with temperature rule within the scope of ignition temperature.Utilize equally the comprehensive thermogravimetric analyzer of STA449C type TG/DAT, only passing through N
2in situation, coal sample is carried out to technical analysis, result is moisture 15.10%, and volatile producibility is 34.05%, and fixed carbon is 45.22%, and all the other are ash content.And matching volatile producibility in 126～276 ℃ of intervals with the relational expression of temperature, △ w meets:
（6），
T-reaction Celsius temperature, ℃.
Step 3: the massfraction that starts each corresponding temperature coal sample from dehydration end point is added to the massfraction △ W of relevant temperature output volatile matter, recycle above-mentioned new conversion ratio
computing formula (4) is calculated conversion ratio; And utilize improved Coats-Redfen integral formula (5) to obtain activation energy.Obtain characteristic temperature point △ x numerical value and bring formula (5) into and carry out matching with 1/T data, can obtain linear equation Y=-7172.51X+1.30.As shown in Figure 2, ignition activation energy is E=59.6 KJmol to result of calculation
-1.
In the present embodiment, △ w is volatile producibility, meets the exponential form of above-mentioned formula (6) matching in 126～276 ℃ of temperature ranges, and volatile matter raises and increases with exponential relationship with temperature 126～276 ℃ of temperature ranges, simulates formula.Formula form is unfixing, can carry out matching according to concrete volatile matter occuring regularity.
The above embodiment is only the preferred embodiments of the present invention, and is not the exhaustive of the feasible enforcement of the present invention.For persons skilled in the art, any apparent change of under the prerequisite that does not deviate from the principle of the invention and spirit, it having been done, within all should being contemplated as falling with claim protection domain of the present invention.
Claims (2)
1. an ignition activation energy analytical approach for low degree of coalification coal spontaneous combustion characteristic, is characterized in that: it specifically comprises the steps:
Step 1: utilize thermogravimetric experimental technique to test and draw thermogravimetric curve and dehydration end point temperature, ignition temperature coal sample;
Step 2: utilize thermogravimetric experimental facilities to carry out technical analysis experiment to coal sample, obtain dehydration end point to the volatile producibility variation with temperature rule within the scope of ignition temperature, obtain the massfraction △ W of relevant temperature output volatile matter;
Step 3: the massfraction that starts each corresponding temperature coal sample from dehydration end point is added to the massfraction △ W of relevant temperature output volatile matter, recycling new reaction conversion ratio
computing formula (4) is calculated reaction conversion ratio:
（4）；
In formula: W
end-volatile producibility while being ignition temperature, %;
The massfraction of corresponding institute output volatile matter during △ W-different temperatures, %;
To in the improved Coats-Redfen integral formula of △ x substitution (5) obtaining, obtain activation energy:
（5）；
In formula: △ x-reaction conversion ratio, %;
E-energy of activation KJ/mol;
R-gas law constant, KJ/molK;
A-pre-exponential factor, s
-1;
T-temperature of reaction, K.
2. the ignition activation energy analytical approach of a kind of low degree of coalification coal spontaneous combustion characteristic according to claim 1, is characterized in that: described step 2 concrete grammar is: utilize thermogravimetric experimental facilities only passing through N
2in situation, coal sample is carried out to technical analysis, obtains volatile producibility, and matching volatile producibility dehydration end point in ignition temperature interval with the relation of temperature, calculate △ w.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105181515A (en) * | 2015-10-19 | 2015-12-23 | 广东电网有限责任公司电力科学研究院 | Method and system for detecting combustion dynamic characteristics of pulverized coal in boiler hearth |
| CN106874641A (en) * | 2016-12-15 | 2017-06-20 | 中国航天空气动力技术研究院 | Silicon nitride passive oxidation model experiment method of calibration and oxidated layer thickness influence factor determine method |
| CN108519301A (en) * | 2018-03-12 | 2018-09-11 | 沈阳环境科学研究院 | It is a kind of to utilize thermogravimetric analyzer evaluation coal and the reactive method of biomass char |
| CN109030768A (en) * | 2018-08-20 | 2018-12-18 | 中国矿业大学 | A kind of measurement method of coal shortest spontaneous combustion period of experiment |
| CN109342498A (en) * | 2018-10-15 | 2019-02-15 | 西安科技大学 | A kind of Coal Self-ignition Process phase judgement method |
-
2014
- 2014-07-30 CN CN201410365712.3A patent/CN104142282A/en active Pending
Non-Patent Citations (1)
| Title |
|---|
| 郝朝瑜等: "低变质程度煤自燃特性的改进着火活化能方法研究", 《中国安全科学学报》 * |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105181515A (en) * | 2015-10-19 | 2015-12-23 | 广东电网有限责任公司电力科学研究院 | Method and system for detecting combustion dynamic characteristics of pulverized coal in boiler hearth |
| CN105181515B (en) * | 2015-10-19 | 2017-12-12 | 广东电网有限责任公司电力科学研究院 | Detect the method and system of coal dust firing dynamic characteristics in boiler furnace |
| CN106874641A (en) * | 2016-12-15 | 2017-06-20 | 中国航天空气动力技术研究院 | Silicon nitride passive oxidation model experiment method of calibration and oxidated layer thickness influence factor determine method |
| CN106874641B (en) * | 2016-12-15 | 2019-05-24 | 中国航天空气动力技术研究院 | Silicon nitride passive oxidation model experiment method of calibration and oxidated layer thickness influence factor determine method |
| CN108519301A (en) * | 2018-03-12 | 2018-09-11 | 沈阳环境科学研究院 | It is a kind of to utilize thermogravimetric analyzer evaluation coal and the reactive method of biomass char |
| CN109030768A (en) * | 2018-08-20 | 2018-12-18 | 中国矿业大学 | A kind of measurement method of coal shortest spontaneous combustion period of experiment |
| WO2020037861A1 (en) * | 2018-08-20 | 2020-02-27 | 中国矿业大学 | Method employing an experiment to measure shortest spontaneous combustion period of coal |
| CN109342498A (en) * | 2018-10-15 | 2019-02-15 | 西安科技大学 | A kind of Coal Self-ignition Process phase judgement method |
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Application publication date: 20141112 |