JP2003215078A - Method of testing heat build-up of coal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of testing heat build-up of coal by which the degree of temperature rise in each brand of coal layer can be evaluated in a short time. <P>SOLUTION: The temperature in a testing device system is held at a temperature T<SB>1</SB>corresponding to a test starting temperature T by preheating a heating machine (15) housing an insulation container (14). On the other hand, the surface moisture and holding moisture of a coal sample pulverized to a prescribed grain size or smaller are removed by drying the sample at a temperature T' under a vacuum by using a vacuum dryer (19) equipped with an evacuating means and a heating means while the sample is packed in an opened container (16). Subsequently, the temperature of the coal sample packed in the container (16) is adjusted to another temperature T<SB>2</SB>corresponding to the test starting temperature T. Then the sample is shifted to the insulation container (14) housed in the heating machine (15) and the atmosphere in the container (14) is replaced with an inert gas and, at the same time, the temperature of the sample is adjusted to the test starting temperature T. Thereafter, an oxidizing gas is supplied to the container (14) and the temperature or temperature change of the coal sample in the container (14) is tracked by means of a temperature data collecting device (12). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for evaluating the degree of temperature rise in a coal seam due to oxidation of coal for each brand in a short time.

[0002]

2. Description of the Related Art <Coal Layer Heat Storage and Spontaneous Ignition> At the coke manufacturing site, coal of various brands is piled up in the yard (coal storage yard). Is selected and charged into a coke oven for dry distillation. The coal loaded in the open field will be stored for a long time before it is used.However, the coal after mining will be oxidized by oxygen in the air during the coal storage to generate heat, which may lead to ignition. Therefore, from the perspective of disaster prevention, it is necessary to manage and understand the difference in heat generation between brands. Not only coal piled in the yard, but also coal layers that come into contact with air may accumulate heat or ignite.

"Journal of the Japan Mining Industry / 85 969 ('69-
1) "(1969), pages 15-20," Coal
Relationship between the initial phenomenon of spontaneous ignition and oxygen concentration in air "
The paper is published, and (a) oxygen concentration and spontaneous combustion
Relationship, (b) oxygen consumption, CO ₂ , CO generation rate, CO / O
₂ , CO₂ / O₂ And the oxygen concentration, (c) spontaneous combustion
We are investigating the relationship between required days and oxygen concentration.

13-in "Die, December 1982 issue"
On page 22, a paper entitled "Oxidation and temperature rise of coal storage-Study on spontaneous combustion of coal (1)-" is published.
Phenomena related to oxidation and heat storage are related to sedimentation consolidation, oxidation heat generation, heat conduction, ventilation, moisture evaporation and condensation, atmospheric environment, coal properties (coalification degree, microstructure, etc.) , Experiments on oxidation reaction heat measurement device (basic studies have been shown on measurement of elevated temperature when a sample is charged into a mahobin and oxygen gas is aerated.

"Shikoku Research Institute Research Bulletin No. 54"
(1989), pp. 48-65, a paper entitled "Evaluation of temperature rising characteristics of coal stored in silo" is published, and experimental method using coal spontaneous ignition device and computer are utilized. The temperature rise characteristics of coal are evaluated by a simulation method in which numerical calculations are performed.

[Journal of the Japan Institute of Energy, Vol. 75, No. 11]
No. (1996), pages 963-969, provides a review entitled "Coal Storage and Handling Technology", which is illustrated in Figure 3 of the section "Spontaneous Heat Generation" on pages 964-965.
And FIG. 4 shows an example of the spontaneous heat generation measuring device and the result.

<Evaluation of spontaneous combustion> JP-A-11-344
Japanese Patent No. 456 discloses a case having a space filled with pulverized coal, a heating device mounted on the lower end side of the case, a closed container for housing these, and a heater for heating an atmosphere in the closed container. The provided pulverized coal self-ignitability evaluation apparatus is shown.

A commercially available spontaneous ignition evaluation device (for example, "Shimadzu spontaneous ignition test device SIT-manufactured by Shimadzu Corporation"
2 ”) can also be used to measure the ignitability.

"Hitachi Zosen Giho, Vol. 43, No. 1," (March 1982), pp. 13 to 19 show commercially available spontaneous ignition test equipment ("Shimadzu spontaneous ignition test manufactured by Shimadzu Corporation"). Device SIT-1 ") and targeting 41 kinds of coal
There are reports on the results of experimental examinations regarding the temperature rise characteristics in the temperature range of 200 ° C., the influence of oxygen concentration, the influence of coal particle size, the influence of coal species, the physical properties of coal (O / C ratio, volatile matter).
The relationship with is shown.

[0010]

As a method for evaluating the degree of temperature rise in the coal seam due to oxidation of coal for each brand in a short time, the reaction surface of coal and oxygen is obtained by crushing coal to 5 mm or less. It is considered that a method of increasing the temperature to increase the temperature rise, and a method of preheating the coal sample to a predetermined temperature in order to evaluate the degree of the temperature increase under acceleration conditions are practical.

However, some brands of coal have not only the surface and the moisture content of the coal but also the moisture contained in the coal. Under the condition that they are dried by a dryer, they are enclosed in such coal. It is difficult to remove water. Therefore, when testing the exothermicity of coal, if the evaluation is made with the water contained therein remaining, the energy for raising the temperature is also used for the thermal energy for raising the temperature of the moisture, thereby increasing the temperature. This hinders the evaluation of the speed level in a short time.

<Object of the Invention> [0012] Under such a background, the present invention provides a test method for exothermicity of coal capable of evaluating the degree of temperature rise in the coal seam of each brand in a short time. It is intended.

[0013]

The method for testing the exothermicity of coal of the present invention is a method for evaluating the degree of temperature rise in a coal seam due to oxidation of coal for each brand of coal.
Preheating the heater (15) that houses the heat-insulating container (14) with the gas introduction tube (9) and the gas discharge tube (10), and adjusts the temperature in the test equipment system to a temperature that matches the test start temperature T. Hold at T ₁ , (b) On the other hand, a vacuum dryer (19) equipped with a vacuum means and a heating means in a state where a coal sample crushed to a predetermined particle size or less is loaded in the open container (16). ) Is used to remove surface moisture and entrapped moisture of the coal sample under vacuum at a temperature T ′, and then the coal sample in the open container (16) is heated to a temperature corresponding to the test start temperature T. that it temperature adjusted until the T _2, (c) the coal sample moisture has been to and temperature control removed, transferred to a thermally insulated container (14) within said heater (15), the heat insulating container ( 1
The atmosphere in 4) is replaced with an inert gas, and the temperature is adjusted to the test start temperature T, and then an oxidizing gas is supplied into the heat insulating container (14) to remove the coal sample in the heat insulating container (14). It is characterized in that the temperature or temperature change is tracked by a temperature data collecting device (12).

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.

In the test method of the present invention, the degree of temperature rise in the coal seam due to oxidation of coal is evaluated for each brand of coal. As in the examples described below, the heat storage of coal in coal stocks varies greatly depending on the brand, so it is important to evaluate each type of brand when managing open-load coal in the yard (pile for each brand). Above is beneficial.

<Requirement (a)> In the present invention, a heater (15) containing a heat insulating container (14) provided with a gas introduction tube (9) and a gas discharge tube (10) is preheated, The temperature in the test apparatus system is kept at a temperature T ₁ that matches the test starting temperature T.

The gas introduction tube (9) is for introducing an inert gas such as nitrogen and an oxidizing gas such as air. For example, a nitrogen switching valve (1) and an air switching valve ( Combine the pipes from 2) to make a common tube for gas supply, and heat the heater for heating to the common tube for gas supply.
It is preferable to attach (3) and pipe so as to lead it into the heat insulating container (14).

The gas discharge tube (10) is a pipe for discharging the inert gas or oxidizing gas supplied into the heat insulating container (14) to the outside of the system.

As the heater (15), an ordinary dryer equipped with a heating means and a fan can be used. It is also possible to use other types of heaters.

As the heat insulating container (14), a container having a heat insulating property such as a heat insulating bottle is used. In the heat insulating container (14), for example, a gas inlet tube (9), a gas exhaust tube (10), and a tight stopper (1
3) Be prepared to wear. As the means (11) for measuring the temperature in the coal layer, for example, a thermocouple can be used.

And, these gas introduction tubes (9),
Gas discharge tube (10), means (11) for measuring the temperature in the coal bed,
The heater (15) including the tight stopper (13) and the heat insulating container (14) is preheated to maintain the temperature in the test apparatus system at the temperature T ₁ corresponding to the test start temperature T.

<Requirement (b)> On the other hand, in the present invention,
Drying a coal sample crushed to a predetermined particle size or less in an open container (16) under vacuum using a vacuum dryer (19) equipped with a vacuum means and a heating means at a temperature T '. Removes surface moisture and contained moisture of the coal sample,
Then, the temperature of the coal sample in the open container (16) is adjusted to a temperature T ₂ corresponding to the test starting temperature T.

As the coal sample, one obtained by crushing coal into a grain size not larger than a predetermined grain size is used. What is a predetermined grain size?
In order to increase the reaction surface between the coal and the oxidizing gas, for example, 10 mm sieve, especially 5 mm sieve is suitable.
Note that it is not necessary to cut the fine powder part in the sample, but if there is a risk that the fine powder will clog the gas introduction tube (9) and interfere with the gas flow, the minimum diameter of the sample particles is It is possible to take measures such that the sample particles do not get stuck in the gas introduction tube (9) by making it smaller than the inner diameter of 9) (for example,
If the inner diameter of the gas introduction tube (9) is 3 mm, the sample particles should be on the 3 mm sieve).

As the open container (16), for example, a hard glass pipe is used. The reason why the container is an open container is to secure a removal path for surface moisture and contained moisture of the coal sample.

The vacuum dryer (19) is a dryer equipped with a vacuum means and a heating means. Even if the surface water of the coal sample can be removed only by heating, it is difficult to remove the contained water, so it is necessary to use a vacuum means together.

The degree of vacuum by the vacuum dryer (19) is set, for example, so that the inside of the system is -700 mmHg or less, particularly -750 mmHg or less (1 mmHg is expressed in international units.
It is 1.3 × 10 ² Pa). The drying temperature T'in vacuum is a temperature at which the total water content of the coal sample can be reduced to 0.5% or less, preferably 0.1% or less under vacuum, for example, about 100 to 107 ° C, particularly 100 to 102 ° C. It is desirable to set it to a degree.

After the surface moisture and the contained moisture of the coal sample are removed, the temperature of the coal sample in the open container (16) is adjusted to the temperature T ₂ corresponding to the test starting temperature T described above.

<Requirement (C)> Since preparation is completed as described above,
Furthermore, in the present invention, the coal sample from which water has been removed and whose temperature has been adjusted is a heat insulating container in the heating machine (15).
Transfer to (14). Then, while replacing the atmosphere in the heat insulating container (14) with an inert gas and adjusting the temperature to the test start temperature T, an oxidizing gas is supplied into the heat insulating container (14) to The temperature or temperature change of the coal sample in () is tracked by the temperature data collector (12).

Nitrogen gas is used as the inert gas, and air is used as the oxidizing gas. The inert gas and the oxidizing gas are preferably heated by the heating heater (3) to a temperature corresponding to the test starting temperature T before being supplied to the heat insulating container (14) in the heater (15). .

In the temperature data collecting device (12), the temperature of the coal sample is measured or the temperature difference from the test start temperature T of the coal sample is measured.

As the above-mentioned test starting temperature T, a predetermined temperature within the range of 50 to 70 ° C. (eg 60 ° C.) is suitable.
It is desirable that the temperatures T ₁ and T _{2 be} substantially the same as the test start temperature T.

<Others> The open container (16) and the heat insulating container (14) may be of a single type each including one set,
It is also possible to carry out the test by providing them as a multi-system by providing a plurality of sets.

[0033]

EXAMPLES The present invention will be further described with reference to examples.

<Testing Apparatus> FIG. 1 is an explanatory view showing an example of an apparatus used for carrying out the method for testing the exothermicity of coal of the present invention.

(1) is a switching valve for nitrogen, (2) is a switching valve for air, (3) is a heater for heating, (4) is a control signal line,
(5) is a gas supply common tube, (6) is a tube joint, and (7) is a control unit. These are arranged outside the heater.

(8) is a temperature control means for the supply gas (control thermocouple), (9) is a gas introduction tube (gas supply common tube), (10) is a gas discharge tube, and (11) is a temperature in the coal bed. Measuring means (thermocouple), (13) is a sealed stopper, and (14) is a heat insulating container (heat insulating bottle). These are installed in the heater (15) (however, (8), (9), (10), (11) are partially out of the system). (12) is a temperature data collecting device.

(16) is an open container (a pipe made of hard glass),
(17) is a water trap device, (18) is a vacuum pump, and (19) is a vacuum dryer. The open container (16) is housed in the vacuum dryer (19).

<Measurement Procedure> The measurement procedure is as follows. Approximately 340 g (dry basis weight) of each brand of coal sample crushed to a size of less than 1.5 mm (under 5 mm sieve) and over 3 mm (over 3 mm sieve), open container (hard glass pipe) with an inner diameter of 40 mm ( Evenly load 16). 2. The vacuum pump (18) raises the temperature in the vacuum dryer (19) to T ′ (100 ° C.) while keeping the pressure in the vacuum dryer (19) negative at 10 mmHg (−750 mmHg). 3. The surface water and the contained water of the coal sample are vaporized, and the water is trapped and removed by the water trap device (17). 4. The above operation is continued until there is no more water trapped in the water trap device (17) (until the total water content of the coal sample is 0.1% or less), and then the vacuum dryer (19) is set to the test start temperature T.
(60 ° C.) and the sample temperature T ₂ is adjusted to T. 5. Test the vacuum dryer (19) of the above 4 at the test starting temperature T (60
In parallel with the timing of setting to (° C), the temperature control means of the supply gas (thermocouple for control) (8), gas introduction tube (gas supply common tube) (9), gas discharge tube (10), inside the coal bed Temperature measuring means (thermocouple) (11), sealed stopper (13) and heat insulation container (heat insulation bottle) (14) are preheated by using a heater (15), and the temperature T ₁ in the test equipment system is tested. Temperature T (60
C)). 6. When the sample temperature reaches the test start temperature T, the open container (hard glass pipe) (16) prepared in 4 above is taken out of the vacuum dryer (19), and the sample inside is heated by a heater (15). The heat-insulated container (heat-insulated bottle) (14) taken out from the above was quickly loaded, and the heat-insulated container (heat-insulated bottle) (14) was supplied with the temperature control means (control thermocouple) (8) for the supply gas and the gas introduction tube ( Gas supply common tube) (9), gas discharge tube (1
0) and the means (thermocouple) for measuring the temperature in the coal bed (11) are inserted into the cap (13). 7. Supply gas temperature control means (control thermocouple) (8) to control unit (7), coal bed temperature measurement means (thermocouple)
(11) to the temperature data collector (12) and the gas inlet tube (common gas supply tube) (9) to the tube joint
Connect to (6) respectively. 8. Open the nitrogen switching valve (1) and supply nitrogen. At this time, the control unit (7) controls the temperature of the supply gas to 60 ° C. by the temperature control means (control thermocouple) (8) for the supply gas.
Adjust with. 9. Switching valve for nitrogen when the display of the means (thermocouple) for measuring the temperature in the coal bed (11) reaches the test start temperature T of 60 ° C.
(1) is closed, the air switching valve (2) is opened, and oxidizing air is supplied at a rate in the range of 10 to 100 ml / min (25 ml / min in this embodiment). The temperature of the supply gas is adjusted by the control unit (7) so that the temperature of the supply gas is 60 ° C. by the temperature control means (control thermocouple) (8). 10. After starting to oxidize the coal, the heater (15) and the feed gas temperature are kept constant (60 ° C). 11. While supplying the oxidizing air, the degree of temperature rise (temperature or temperature change) in the coal seam is recorded using the temperature data collector (12). 12. If air for oxidation is introduced for about 3 hours, the degree of temperature rise can be confirmed, and then the test is completed.

<Measurement Results> In accordance with the above-mentioned measurement procedure, evaluation tests were carried out on four brands of coal having different origins and total water contents. The results are shown in Figure 2. In FIG. 2, the horizontal axis is “the elapsed time since the air switching valve (2) was opened and the supply of the oxidizing air was started”, and the vertical axis was the “temperature data collecting device (12) that collected data at 1 second intervals. The temperature in the coal seam (thermocouple (11)) ". In addition, the predetermined time (200 minutes, 400 minutes,
Table 1 shows the readings of the temperature of the coal bed after the elapse of 600 minutes and 660 minutes.

[0040]

[Table 1]      Total moisture of coalCoal bed temperature (℃)   Brand (%) Initial setting 200 minutes later 400 minutes later 600 minutes later 660 minutes later   Coal A 24.6 60 73 87 95 98   Coal B 9.0 60 65 66 66 66   Coal C 9.0 60 61 62 62 62   Coal D 8.0 60 61 62 62 62

From FIG. 2, among the four brands used in the test,
The temperature rise from the system in which Coal A was kept at a constant temperature (60 ° C in this case) was remarkable, and the evaluation of exothermicity
The result is that heat is easily generated in the order of A << Coal C <Coal B ≦ Coal D. Therefore, when storing Coal A brand coal, it should be noted that coal storage management should be carried out while keeping in mind that the brand tends to generate heat. Further, it can be seen from FIG. 2 that it is possible to know the tendency of exothermicity of each brand in the first 3 hours or less.

[0042]

According to the test method of the present invention, the degree of temperature rise of each brand of coal can be evaluated in a short time.
Therefore, it is possible to know the degree to which spontaneous combustion occurs when coal is loaded in the yard, etc., and safe coal stock management becomes possible.

Further, even when coal is ignited by a rapid temperature rise in the coal bed during the test, the air switching valve is used.
By closing (2) and opening the nitrogen switching valve (1), it is possible to extinguish the suffocation, so a prompt response can be achieved.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of an apparatus used for carrying out the method for testing the exothermicity of coal of the present invention.

FIG. 2 is a graph showing the results when an evaluation test was performed on four brands of coal in the examples.

[Explanation of symbols]

(1)… Switching valve for nitrogen, (2)… Air switching valve, (3)… Heating heater, (4)… Control signal line, (5)… Gas supply common tube, (6)… Tube joint, (7)… Control unit, (8) ... Supply gas temperature control means (control thermocouple), (9)… Gas introduction tube (gas supply common tube), (10)… Gas discharge tube, (11)… Means (thermocouple) for measuring the temperature in the coal bed, (12)… Temperature data collection device, (13) ... tight stopper, (14)… Insulation container (insulation bottle), (15)… Heating machine, (16)… Open container (hard glass pipe), (17) ... Water trap device, (18) ... vacuum pump, (19)… Vacuum dryer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masato Fukuda             Kansai heat, 1-1 Ohama-cho, Amagasaki city, Hyogo prefecture             Chemical Research and Development Center F-term (reference) 2G040 AA00 AB12 AB15 BA25 CA02                       CB11 DA03 EA01 FA05

Claims (2)

[Claims] 1. A method for evaluating the degree of temperature rise in a coal bed due to oxidation of coal for each brand of coal, comprising: (a) a gas introduction tube (9) and a gas discharge tube (1).
The heating device (15) accommodating the heat-insulating container (14) attached with (0) is preheated to keep the temperature in the test apparatus system at the temperature T ₁ corresponding to the test start temperature T. ) On the other hand, a coal sample crushed to a predetermined particle size or less is loaded in an open container (16), and a vacuum dryer (19) equipped with a vacuum means and a heating means is used under vacuum at a temperature T ′. By drying, the surface water and the contained water of the coal sample are removed, and then the temperature of the coal sample in the open container (16) is adjusted to a temperature T ₂ corresponding to the test start temperature T. (C) The coal sample from which water has been removed and whose temperature has been adjusted is transferred to the heat insulating container (14) in the heater (15), and the atmosphere in the heat insulating container (14) is replaced with an inert gas. In addition, after adjusting the temperature to the test start temperature T, the insulated container
A method for testing the exothermicity of coal, characterized in that an oxidizing gas is supplied into the (14) and the temperature or temperature change of the coal sample in the heat insulating container (14) is traced by a temperature data collecting device (12). 2. A test starting temperature T is a predetermined temperature within a range of 50 to 70 ° C., a temperature T ₁ and a temperature T ₂ are substantially a test starting temperature T, and a temperature T ′ is under vacuum. The test method according to claim 1, wherein the temperature is a temperature at which the total water content of the sample can be reduced to 0.5% or less.