JPH09316471A - Production of coal fuel molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing coal fuel molding capable of lowering characteristic water content and suppressing collapse of shape and spontaneous ignition. SOLUTION: Low-grade coal is ground into <=1000×m particle diameter by a wet type grinder 14 to afford ground coal, and water in slurry containing the ground coal is heated through a preheater 21 and a heater 22 to over-heated water of >=270 deg.C and the slurry is subjected to hot water treatment at the same temperature for >=5min to convert the ground coat into modified coal. Then, the modified coal is separated by a dehydrator 31 and dried by a drier 32 and compressed under 2 ton/cm<2> pressure by a molding machine 42 to afford a coal fuel molding. Since pores of raw coal are made to collapse and characteristic water content as well as hygroscopic property are lowered by modification, a molding obtained from the modified coal has characteristic low water content and hardly causes collapse of shape and since the specific surface area of the molding is small, the molding hardly causes spontaneous ignition.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a coal fuel molded body.

[0002]

2. Description of the Related Art Low grade coal, such as lignite, subbituminous coal and lignite, which is mined in a coal mining field, has a large number of pores inside and has hygroscopic carboxyl groups and hydroxyl groups on the surface. Therefore, the water content including pore water is 25 ~
Since it is as large as 65% by weight and the calorific value is small, it is disadvantageous as a fuel. Furthermore, since the ignition temperature is low and the specific surface area is large due to the pores, it is easy to spontaneously ignite due to weathering or a change in shape during transportation, which makes transportation and storage difficult. Therefore, conventionally, a method of improving handling property during transportation (JP-A-56-2394) and a method of suppressing spontaneous ignition (JP-A-2-298586) have been proposed.

Of these, the former converts the mined brown coal into a slurry, transports it from the mining site to the collection site in the form of a water slurry, and then dehydrates it, granulates it, dehydrates and dries it, and collects it. By transporting the granules in the form of granulated spheres, spontaneous ignition due to weathering, dust generation and scattering due to drying, etc. are suppressed, and the handling property during transportation is improved.

In the latter, the granular coal after pulverization is dried to a water content according to the type of coal to produce dry coal, and then water is sprayed onto the dry coal in an amount to remove a desired amount of heat from the dry coal by evaporation. However, the dry coal is cooled by evaporating the sprayed water, and the spontaneous combustion of the granular coal obtained by this method is considerably suppressed.

[0005]

However, in the above-mentioned method, although the water content is reduced by drying, it is difficult to remove the intrinsic water content and the carboxyl groups on the surface by only drying, and therefore the water content is reduced. Still many. Further, during transportation or storage, moisture may be absorbed to cause shape collapse or weathering, which may cause spontaneous ignition.

The present invention has been made under such circumstances, and an object thereof is to provide a method for producing a coal fuel molded body which reduces the water content and suppresses shape collapse and spontaneous combustion. It is in.

[0007]

According to the invention of claim 1, a step of wet pulverizing low-grade coal to obtain pulverized coal having a particle size of 1000 μm or less, and contacting the pulverized coal with hot water of 270 ° C. or more. And a step of drying the reformed carbon, and a step of compressing the dried reformed carbon to obtain a coal fuel molded body.

A second aspect of the present invention is characterized in that, in the first aspect of the present invention, dry reformed coal is mixed with wood powder and then compressed to obtain a coal fuel molded body. The invention of claim 3 is characterized in that, in the invention of claim 1, the time for contacting the crushed coal with hot water is 5 minutes or more. The invention of claim 4 is characterized in that, in the invention of claim 1 or 3, the pressure when compressing the dried reformed carbon is 2 ton / cm ² or more. The invention of claim 5 relates to claim 2
In the invention described above, the pressure at the time of compressing the dry modified coal mixed with wood flour is 2 ton / cm ² or more.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. FIG. 1 is a configuration diagram showing an embodiment of an apparatus for producing a coal fuel molded body for carrying out the method of the present invention. Reference numeral 14 in the drawing denotes a wet crusher, and a hopper 11 and a water storage tank 13 are provided on the upstream side of the wet crusher via a coarse crusher 12 and a feeder 11a. Further, a slurry slurry storage tank 16 is provided downstream of the wet crusher 14 via a grinding slurry storage tank 15.
Is provided. A reforming reactor 23 is provided downstream of the supply slurry storage tank 16 via a preheater 21 and a heater 22, and a cooler 2 is provided downstream of the reforming reactor 23.
A dehydrator 31 is provided through the pressure adjusting unit 25, the pressure adjusting unit 25, and the reformed carbon slurry storage tank 26. The wastewater 51 separated by the dehydrator 31 is discarded. A dryer 32 is provided downstream of the dehydrator 31 and, for example, the reformed coal storage tank 3 is provided downstream thereof.
A molding machine 42 is provided via 3, the hopper 41, and the feeder 41a.

In such an apparatus for producing a coal fuel molded body, first, low-grade coal such as brown coal, subbituminous coal, lignite and the like is charged from the hopper 11 to the coarse crusher 12 through the feeder 11a and coarsely pulverized. . Here, the low-grade coal is, for example, 17%
It has a degree of inherent moisture. Subsequently, the coarsely crushed low-grade coal is put into the wet crusher 14 together with the water from the water storage tank 3 and wet crushed to obtain crushed coal having a particle size of 1000 μm or less.

Next, the crushed slurry containing crushed carbon is stored in the crushed slurry storage tank 15. Thereafter, for example, a crushed slurry having a slurry concentration of 25% by weight is sent from the crushed slurry storage tank 15 to the supply slurry storage tank 16 and is fed to the preheater 21 at, for example, 1
After preheating to about 50 ° C., with the heater 22, for example, 270
It is sent to the reforming reactor 23 while being heated to about ℃, for example, 2
The pulverized coal in the slurry is brought into contact with hot water at 270 ° C. or higher in the slurry by heating to 70 ° C. or higher for 5 minutes or longer (hot water treatment).

Since the temperature of the hot water is high in the reforming reactor 23, the pressure is high. The reforming reactor 23 is provided with a heat medium trace for maintaining the temperature. Therefore, under high-temperature and high-pressure conditions, part of the interstitial water and inherent water of the crushed coal in the slurry is removed, the pores are crushed, and further some of the carboxyl groups and hydroxyl groups on the surface are removed, and crushed. The charcoal is reformed into reformed charcoal. In addition, the wax content of the crushed charcoal exudes near the surface during cooling of the reformed charcoal and becomes hydrophobic. In other words, the crushed coal is irreversibly dehydrated.

Subsequently, the reformed carbon slurry containing the obtained reformed coal is sent to a cooler 24, cooled to, for example, about 90 ° C., and then the pressure is temporarily reduced by a pressure adjusting unit 25 to separate gas and liquid. From the modified coal slurry to the storage tank 26 and stored there. Next, the reformed coal slurry is sent to the dehydrator 31, where water and the reformed coal are separated, and then only the reformed coal is sent to the dryer 32 and dried there. The dried reformed carbon is stored once in the reformed coal storage tank 33 and then charged into the molding machine 42 through the hopper 41 and the feeder 41a, where it is compressed at a pressure of 2 ton / cm ² , for example. As a result, it is molded into a predetermined shape, for example, an almond shape, and a coal fuel molded body is obtained.

In the above, the particle size of the crushed coal is 1000 μm
It is desirable to make the following. If the particle size is larger than 1000 μm, the intrinsic water content of the crushed charcoal can be removed,
Since the hydrothermal treatment reaction does not proceed sufficiently, the crushed coal cannot be sufficiently modified, and as a result, there is a high possibility that substances that adversely affect the shape change after molding remain in the crushed coal. Because.

Further, the temperature of hot water for the hot water treatment is preferably 270 ° C. or higher. This is because if the temperature is lower than 270 ° C., the intrinsic water content of the crushed coal will be insufficiently removed. Furthermore, it is desirable that the treatment time of the hot water treatment be 5 minutes or more.
This is because if the treatment time is less than 5 minutes, the inherent moisture is not removed so much. Furthermore, the pressure during molding is 2 tons / c
m ² or more. Pressure is 2 ton / cm ²
This is because if it is smaller, the crushing strength and the strength against falling are reduced. These conditions were determined from the experimental results of the examples described later.

In such a method for producing a coal fuel molded body, pulverized coal is treated with hot water to obtain reformed carbon, and the reformed carbon is compressed to produce the molded body, so that the intrinsic water content is reduced. ,
It is possible to obtain a coal fuel molded body that is unlikely to cause shape collapse or spontaneous combustion. In other words, the reformed charcoal removes its intrinsic water content by reforming, and the pores are crushed to reduce the specific surface area, so less water is attached, and further, some of the hygroscopic carboxyl groups and hydroxyl groups on the surface are removed. As a result, the amount of water absorbed by them also decreases.

Therefore, the coal fuel molded body obtained by molding such a reformed coal has a small intrinsic water content and a low hygroscopicity. As described above, when the amount of the intrinsic water is small, a fuel having a large calorific value is obtained, and the shape collapse hardly occurs together with the decrease of the swelling property due to the low hygroscopicity. As described above, the specific surface area of the reformed coal is significantly smaller than that of the low-grade coal before reforming, so the surface energy of each reformed coal is considerably smaller than that before reforming. Become. For this reason, the surface energy of the coal fuel molded body obtained from the reformed coal is significantly reduced as a whole, and accordingly spontaneous combustion is less likely to occur. Further, since the shape of the coal fuel molded body is less likely to collapse, spontaneous combustion due to shape collapse such as weathering is less likely to occur. As a result, the handling property during transportation and storage is improved, the fuel becomes useful as a fuel, and the usefulness of the low-grade coal is increased. Therefore, it is possible to effectively utilize the low-grade coal which is almost unused at present.

In the above, the coal fuel molded body used in the present invention may contain wood powder, and the inclusion of wood powder in this way can increase the strength as compared with the case of using only low-grade coal. it can. In this case, the content of wood powder is preferably about 20%.

[0019]

[Examples] Examples carried out to determine the conditions for carrying out the present invention will be described below together with comparative examples. (Example) 1. Lignite (Roy Young from Australia, intrinsic moisture 1
4.7%, ash content 1.5%, carboxyl group-related 6.3%
O (oxygen)), subbituminous coal A (Indonesian asam asam, intrinsic moisture 18.5%, ash content 1.6%, carboxyl group-derived 3.8% O (oxygen)), subbituminous coal B (Indonesian burau, intrinsic moisture) 30% slurry of 12.9%, ash 1.2%, carboxyl group-derived 2.5% O (oxygen))
Were prepared, and the low-grade coal in the slurry was made into a pulverized coal having a predetermined particle size by a wet pulverizer, and the temperature of hot water was adjusted in a stirring type autoclave with an internal volume of 5 liters. Hot water treatment was performed by changing the treatment time. After the hot water treatment, the reformed carbon was separated and dried, and then compressed with a molding machine at a pressure of 2 ton / cm ² to obtain an almond type coal fuel molded body.

In addition to measuring the intrinsic water content and ash content of the obtained reformed coal, the molded coal fuel was stored in the atmosphere in a room where it was not exposed to sunlight or rain wind, and the shape change after 6 months (exposure test) )It was confirmed. The results are shown in Table 1 for brown coal.
(Examples 1 to 5 and Comparative Examples 1 and 2), and Table 2 (Examples 11 to 16 and Comparative Examples 11 to 13) for the subbituminous coal A,
Table 3 (Examples 21 to 24 and Comparative Examples 21 to 24) shows the subbituminous coal B, respectively.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

[Table 3]

From these results, in any of the low-grade coals, when the particle size of the crushed coal is 1000 μm or more, the specific water content of the reformed coal is removed to some extent, but the shape of the coal fuel molded body after molding is obtained. It was confirmed that a change occurred (Comparative Examples 11 and 21). Also, when the temperature of hot water during hot water treatment is lower than 270 ° C (265 ° C, 256 ° C), it is confirmed that the intrinsic water content is not removed so much and that the shape of the coal fuel molded body after molding is changed. (Comparative Example 1,
12, 22, 23). Furthermore, when the treatment time of the hot water treatment was shorter than 5 minutes, it was confirmed that the intrinsic water content and the carboxyl group were not removed so much and that the shape change occurred in the coal fuel molded body after molding (Comparative Example 2, 13, 2
4). Therefore, the reforming conditions are as follows:
It was confirmed that the following crushed coal was used and that the crushed carbon was subjected to hot water treatment with hot water at 270 ° C. or higher.

From the results of this experiment, it can be inferred that the higher the hot water temperature, the lower the specific water content of the reformed coal under the same other conditions. It is speculated that the smaller the particle size and the longer the time of hot water treatment, the smaller the amount of intrinsic water in the reformed coal.

2. After crushing sub-bituminous coal (Insam Asam from Indonesia) crushed coal (particle size 1000 μm or less) with hot water at 300 ° C. for 10 minutes, separating and drying it in the air, the reformed coal was changed in pressure. A crushing test, a drop test, and an exposure test were performed for each coal fuel molded body that was compressed and molded (Examples 31 to 33). Further, the same test was performed on each of the molded bodies obtained by molding the crushed sub-bituminous coal (particle size: 1000 μm or less) as raw coal without using the reformed coal as it is (Comparative Example 31). ~ 33).

Further, the same test is carried out on the mixed powder obtained by mixing the modified carbon of the sub-bituminous coal obtained in the same conditions as in the example with 1/4 amount of the modified carbon (Examples 34 and 35). A similar test was performed for each molded body obtained by molding the mixed powder obtained by molding the pulverized sub-bituminous coal as raw coal without modifying the crushed coal with the wood powder as in the example (Comparative Example). 34-36).
Table 4 shows the results. In the table, the crushing test shows the crushing strength when the coal fuel molded body is broken, and the drop test shows the average value of the number of times when the coal fuel molded body is dropped from a height of 2 m and broken.

[0028]

[Table 4] In Examples 31 to 33, it was confirmed from the results of the exposure test that the coal fuel molded bodies obtained by molding after forming the modified coal did not cause shape collapse regardless of the molding pressure, and from the results of the crushing test. If the molding pressure is 2 ton / cm ² or more, the crushing strength will be remarkably increased, so the molding pressure is 2 ton / cm ²
It was found that the above is desirable. On the other hand, in Comparative Examples 31 to 33, it was confirmed from the result of the exposure test that the coal fuel molded bodies obtained by molding the raw coal as it was without using the reformed coal caused shape collapse regardless of the molding pressure.

Further, in the case of a mixed powder of subbituminous coal and wood flour, although it was confirmed from the results of the crushing test and the drop test that the strength is greater than that of the subbituminous coal, even when the raw coal is molded as it is, As a result of the exposure test, it was confirmed that cracks were formed on the surface of the molded body (Comparative Examples 34 to 36). When molded after mixing modified charcoal and wood flour, the crushing strength is quite large, and the number of drops is significantly large, so the strength is very large, and further, the shape collapse does not occur as a result of the exposure test. Was confirmed (Examples 34 and 35), and thus, it was confirmed that the method of the present invention is effective for the mixed powder of the modified carbon of subbituminous coal and the wood powder. It should be noted that spontaneous combustion was not observed in the coal fuel molded body obtained from the reformed coal.

[0030]

EFFECTS OF THE INVENTION According to the present invention, it is possible to obtain a coal fuel molded body which has a small amount of intrinsic water content and is unlikely to cause shape collapse or spontaneous ignition. Therefore, the calorific value is large and the molded body can be handled during transportation or storage. An excellent coal fuel molded body can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of an apparatus for producing a coal fuel molded body for carrying out the method of the present invention.

[Explanation of symbols]

 14 Wet pulverizer 23 Reforming reactor 31 Dehydrator 32 Dryer 42 Molding machine

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masao Tsurui, 14-1, 1-1 Minami-Biery, Yokohama-shi, Kanagawa JGC Corporation Yokohama Business Office (72) Inventor, Kazuhiro Shibata 9-3 Nagisa, Onahama, Iwaki, Fukushima Prefecture Japan Com Co., Ltd. Onahama Business Headquarters (72) Inventor Hitoshi Ogawa 9 No. 3 Nagisa, Onahama, Fukushima Prefecture Japan Com Co., Ltd. Onahama Business Headquarters, (72) Masayuki Yui 9 No. 3 Nagisa Beach, Iwaki, Fukushima Prefecture Japan Com Co., Ltd., Onahama Business Headquarters (72) Inventor Shinji Takano, 9-3 Nagisa, Onahama, Iwaki, Fukushima Prefecture Japan Com Co., Ltd. (72) Hideaki Okada, 9 Nagisa, Onahama, Iwaki, Fukushima Prefecture Japan Com Co., Ltd., Onahama Business Division

Claims (5)

[Claims] 1. A low-grade coal is wet-ground to obtain a particle size of 1000.
a step of obtaining pulverized charcoal of μm or less, a step of contacting the pulverized charcoal with hot water of 270 ° C. or higher to obtain a reformed charcoal, a step of drying the reformed charcoal, and a step of compressing the dried reformed charcoal. And a step of obtaining a coal fuel molded body, the method comprising the steps of: 2. A coal fuel molded body is obtained by mixing dry modified coal with wood powder and then compressing the powder.
A method for producing the coal fuel molded body described. 3. The method for producing a coal fuel molded body according to claim 1, wherein the time for contacting the crushed coal with hot water is 5 minutes or more. 4. The pressure for compressing the dried reformed coal is 2
The method for producing a coal fuel molded body according to claim 1 or 3, wherein the amount is ton / cm ² or more. 5. The method for producing a coal fuel molded body according to claim 2, wherein the pressure at the time of compressing the dried reformed carbon mixed with wood powder is 2 ton / cm ² or more.