JP2631825B2 - Method and apparatus for producing high concentration coal / water slurry - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing a high-concentration coal / water slurry by mixing coal, water and a dispersant. A method and apparatus for producing high-concentration coal / water slurry at low cost by reducing the energy required for grinding by drastically reducing the energy required for grinding and improving the coarse particle removal efficiency by concentrating to a set concentration after wet grinding. It is. High-concentration coal / water slurry refers to a coal concentration of 60 to 80, which comprises finely pulverized coal, water and some additives.
It is a fluid fuel that can be burned as it is in a combustion device such as a boiler without dehydration by a mixture of weight%.

[0002]

2. Description of the Related Art Conventionally, high concentration coal / water slurry (co
al water mixture (CWM), as shown in FIG. 9, raw coal is coarsely pulverized by a coarse pulverizer 10 and then introduced into a high-concentration wet pulverizer 12 such as a wet ball mill together with water and a dispersant, as shown in FIG. After wet grinding with the wet grinding machine 12 at the set concentration of the product CWM, vibrating sieve,
The coarse particles are removed by a coarse particle remover 14 such as an auto-strainer, stirred and mixed by a stirring mixer 16 such as a line mixer, and cooled by a cooler 18. Thus, the high concentration C
The production of WM is performed in a closed system, and the difference between the CWM concentration in the wet grinding step in the wet grinding machine 12 and the product CWM concentration is less than 0.5% by weight (the coal concentration of the product CWM is slightly Bigger).

With respect to the adjustment of the concentration of CWM, there has been known a method in which wet pulverization is carried out at a low concentration, followed by dehydration concentration / kneading treatment to increase the concentration (for example, Japanese Patent Publication No. 5-76988, Japanese Patent Application Laid-Open No. 60-220490).

[0004]

In the conventional method shown in FIG. 9, since the CWM concentration in the wet mill 12 is substantially equal to the product CWM concentration, there is a problem that the wet grinding power is large and the product cost increases. is there. Further, in the method described in the above-mentioned publication, the grinding power can be reduced by wet grinding at a low concentration, but the power required in the dehydration / concentration step is large, and the energy required for drying the coal is large, and the total power is low. There is a problem that the required energy is large.

[0005] In the actual machine, a continuous grinding process is performed. In addition, in order to reduce noise, the wet grinding machine is inevitably housed in a soundproof room. Has been found to rise to a level of 70-80 ° C., and conventionally, the CWM is cooled to room temperature by a CWM cooler in the final step in order to prevent evaporation of water. In the present invention, water is evaporated and concentrated by utilizing the heat energy of a coal / water slurry, but no known material similar to this has been found. Further, no method was found in which dry pulverized charcoal was added and mixed and concentrated at 0.6 to 3.0% by weight.

[0006] The power of wet pulverization of a high-concentration coal-water slurry varies greatly with small changes in coal concentration. In order to reduce the wet grinding power, it is desirable to carry out wet grinding at a low concentration.However, the conventional method has a problem in that the required energy in the downstream enrichment step is large, and the total power consumption is reduced. Has not been reached. Also, in the coarse particle removing step performed after the wet pulverization, there is a problem that the higher the concentration of the coal / water slurry, the lower the passing property of the screen and the lower the coarse particle removing efficiency. On the other hand, in high-concentration wet pulverization in a large mill, when the high-viscosity slurry receives shear energy or impact energy in the mill, a part of the slurry is converted to heat energy, so the temperature of the slurry increases, In the manufacturing apparatus, the temperature rises to about 70 to 80 ° C. Therefore, as described above, a cooling step is provided downstream.

[0007] In view of the above points, the inventors diligently studied a method of reducing the power of wet grinding of CWM and improving the efficiency of removing coarse particles. The present invention has been made based on the above-described study results, and an object of the present invention is to reduce the coal concentration by evaporating water by utilizing the high temperature of the coal / water slurry at the outlet of the wet mill. Concentrate in the range of 0.6 to 3.0% by weight and reduce the grinding power by wet grinding with a lower concentration than the product CWM, improve the efficiency of removing coarse particles, and significantly reduce the power consumption per unit of CWM production High concentration C
An object of the present invention is to provide a method and an apparatus for manufacturing a WM.

[0008]

In order to achieve the above object, a method for producing high-concentration coal according to the present invention comprises a step of mixing coal, water and a dispersant, and a step of wet-milling coal. In the method for producing a water slurry, wet pulverization is performed at a concentration lower than the set concentration of the product coal / water slurry in the range of 0.6 to 3.0% by weight, and then the particle size is adjusted. It is characterized in that the retained heat is concentrated to the set concentration as at least a part of the heat source. In this case, it is preferable to perform wet pulverization, and then adjust the particle size to 200 mesh or less and 75 to 85% by weight.

[0009] In the above method, the coal / water slurry is concentrated by stirring the coal / water slurry in an open-top stirring tank and evaporating water by the retained heat of the coal / water slurry. The method of cooling the slurry and the concentration of the coal / water slurry are performed by stirring the coal / water slurry in an open-top stirring tank having a heating function and evaporating water by the added heat and the retained heat of the coal / water slurry. In this case, a method is adopted. Also, coal and
Concentration of the water slurry can be performed by sucking gas from above with a closed stirring tank and evaporating water by the retained heat of the coal / water slurry while reducing the pressure in the stirring tank. Further, the coal / water slurry can be concentrated by adding and mixing dry pulverized coal. In this case, since the water evaporates also by the retained heat of the coal / water slurry, it can be concentrated in a shorter time.

In the method of the present invention, wet pulverization is carried out at a low concentration in the range of 0.6 to 3.0% by weight lower than the set concentration of the product CWM. rare. On the other hand, if you exceed this range,
The energy required for concentrating to the target product concentration after pulverization increases, and the total CWM production power consumption increases. The particle size is adjusted to a range of 75 to 85% by weight of 200 mesh or less.
Coarse particles increase, stability is reduced, and sedimentation of coal particles makes it easier to form a hard sediment layer. On the other hand, when it exceeds this range, the power required for pulverization increases and agglomerates are easily generated.

An apparatus for producing a high-concentration coal / water slurry according to the present invention comprises a high-concentration wet pulverizer for wet-pulverizing coal while mixing coal, water and a dispersant, and a coal / water slurry from this wet-pulverizer.
A coarse particle remover for removing coarse particles in the water slurry, a stirring mixer for stirring and mixing the coal / water slurry from which coarse particles have been removed, and a coal / water product by cooling the stirred and mixed coal / water slurry. In a high-concentration coal / water slurry production apparatus comprising a slurry-based cooler, a water content in the coal / water slurry is evaporated between the coarse particle remover and the agitating mixer by heat retained in the coal / water slurry. And a water evaporator for increasing the concentration of coal / water slurry.

A moisture evaporator is provided between the agitating mixer and the cooler for evaporating moisture in the coal / water slurry by the retained heat of the coal / water slurry to increase the concentration of the coal / water slurry. You may. In these devices, the water evaporator may be an open-top stirring tank with a stirrer inside, or a closed stirring tank with a stirrer inside,
Further, the stirring tank is provided with a heating means.

Further, the apparatus of the present invention is provided with a stirring and mixing tank for adding dry pulverized coal and stirring and mixing to increase the concentration of the coal / water slurry between the coarse particle remover and the stirring and mixing machine. It may be configured.

[0014]

FIG. 1 shows an example of an apparatus for carrying out the method for producing a high-concentration coal / water slurry of the present invention. Numbers 10 to 18 are the same as in FIG. 70 to 8 which is 0.6 to 3.0% by weight lower than the target concentration and is discharged from the wet mill 12 such as a wet ball mill.
The high-concentration CWM of 0 ° C. is introduced into a coarse sieve 14 such as an automatic strainer by vibrating sieve and introduced into a moisture evaporator 20 such as a collect tank having a low-speed stirring function whose upper part is open to the atmosphere. After stirring to evaporate water and concentrate to the target product CWM concentration, high-speed stirring is performed by a stirring mixer 16 such as a line mixer, and further cooled to normal temperature by a cooler 18 to obtain a high-concentration product. CWM
To manufacture. The high concentration refers to a coal concentration of 60 to 80% by weight. In addition, low-speed stirring is 30 to 500 rp.
m, high-speed stirring refers to 600-4000 rpm.
Further, a method is also applicable in which a collect tank having a closed upper portion is used, and gas is sucked from the upper portion to evaporate water while reducing the pressure.

It is more effective if the above-mentioned collect tank is provided with a heating function. In other words, when the amount of heat required for water evaporation is insufficient with the heat energy of the CWM itself discharged from the wet crusher 12, the water evaporator 20 is heated by a tank having a heating function to supplement the heat amount. The water may be evaporated while stirring.

FIG. 2 shows another example of an apparatus for implementing the method of the present invention. As shown in FIG.
May be downstream of the high-speed stirring process, that is, downstream of the stirring mixer 16, and may be configured to simultaneously perform concentration and cooling by partially providing a function as a CWM cooler. Good. Other configurations and operations are the same as those in FIG.

FIG. 3 shows still another example of an apparatus for implementing the method of the present invention. As shown in FIG. 3, a stirring and mixing tank 24 such as a low-speed stirring tank is provided between the coarse particle remover 14 and the stirring and mixing machine 16, and the stirring and mixing tank 24 has CWM of 0.6 to 3.0. The dry pulverized charcoal required for concentrating by weight is newly added, and the mixture is stirred and mixed at a low speed. In this case, moisture is also evaporated and concentrated by the retained heat of the CWM. Other configurations and operations are the same as those in FIG.

As described above, the power required for pulverization is reduced by 10 to 30% by lowering the CWM concentration in the wet pulverization process in the range of 0.6 to 3.0% by weight from the product CWM concentration.
To some extent. Further, the throughput of the coarse particle removing machine can be increased by about 10 to 30%.

[0019]

【Example】

Example 1 Coal having the properties shown in Table 1 (from Australia, Mount Sole coal), water, and a polystyrene sulfonic acid-based dispersant (Polynas PS-1 manufactured by Tosoh Corporation) were put into a wet ball mill at a predetermined ratio, and various types were added. Wet pulverization was performed at the slurry concentration, a high-concentration coal / water slurry was produced under the conditions shown in Table 2, and the pulverizability was compared and examined. The pulverizability was compared with the required pulverization time required to pulverize the product to a target particle size of 200 mesh sieve passing rate (75 μm or less) of 80%. FIG. 4 shows the results. It can be seen that the pulverizability improves with the decrease in the slurry concentration at the time of pulverization, and when the product slurry concentration is 69% by weight, the pulverization time can be reduced by about 15% when the pulverization is performed at 68% by weight, which is 1% lower. 4 can be read.

[0020]

[Table 1]

[0021]

[Table 2]

Example 2 Coal, water, and polystyrene sulfonic acid-based dispersant (Polynas PS-1 manufactured by Tosoh Corporation) having the properties shown in Table 1 were put into a wet ball mill at a predetermined ratio, and wet pulverized at various slurry concentrations. Then, high-concentration CWM was prepared by the conventional method of the flow shown in FIG. 5 under the production conditions shown in Table 3, and high-concentration CWM was prepared by the concentration method of the present invention shown in FIG. 6 under the production conditions shown in Table 4. That is, in the conventional method, as shown in FIG. 5, batch-type wet pulverization is performed by adding coarsely pulverized charcoal, water, and a dispersant to a wet-type ball mill.
The product was stirred at a high speed of 00 rpm for 10 minutes to prepare a product CWM. In the enrichment method of the present invention, as shown in FIG. 6, batch-type wet pulverization is performed by charging coarsely pulverized coal, water and a dispersant into a wet ball mill, and the slurry is heated in a heater (constant temperature water tank) for 8 hours.
After heating to 0 ° C., the mixture was concentrated by 1.5% by weight by evaporating water, and then the slurry was homogenized at 5000 rpm with a homomixer.
The product CWM was prepared by high-speed stirring for 10 minutes.

[0023]

[Table 3]

[0024]

[Table 4]

In the actual machine, even if a heater is not provided, continuous wet pulverization is performed, and since the pulverizer is housed in a soundproofing chamber, heat radiation is small.
To 80 ° C., but in a batch-type experimental wet ball mill as in this example, the grinding step is not performed continuously and the mill is not housed in a closed room for soundproofing. The heat dissipation is large, and the CWM temperature rises only up to about 40 to 45 ° C. For this reason, 80
Heated to ° C. 7 and 8 show the test results in this example. In the concentration method of the present invention, the ability to increase the concentration of the slurry was slightly improved as compared with the conventional method. In addition, the time required for pulverization could be reduced by 10 to 30% in the concentration range in which the experiment was performed.

[0026]

As described above, the present invention has the following effects. (1) Utilizing the fact that the temperature of the coal / water slurry at the outlet of the wet pulverizer is high, the water is evaporated, and the coal concentration of the coal / water slurry is concentrated in the range of 0.6 to 3.0% by weight. Wet pulverization at a lower concentration than coal / water slurry can reduce the pulverizing power, and because of the low concentration, can increase the throughput of the coarse particle remover and improve the coarse particle removal efficiency. It is possible to significantly reduce the production power consumption unit of the product high concentration coal / water slurry.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an example of an apparatus for implementing a method for producing a high-concentration coal / water slurry of the present invention.

FIG. 2 is a system diagram showing another example of an apparatus for performing the method of the present invention.

FIG. 3 is a system diagram showing still another example of an apparatus for performing the method of the present invention.

FIG. 4 is a graph showing the results in Example 1 and showing the relationship between the coal concentration of CWM and the time required for grinding.

FIG. 5 is a graph showing a conventional method C as a comparative example in Example 2.
FIG. 3 is a system diagram showing a WM preparation flow.

FIG. 6 is a system diagram showing a CWM preparation flow of the concentration method of the present invention in Example 2.

FIG. 7 is a graph showing the results of Example 2 and showing the relationship between product CWM concentration and viscosity (high concentration property) in the conventional method and the concentration method of the present invention.

FIG. 8 is a graph showing the results of Example 2 and showing the relationship between the product CWM concentration and the required pulverization time in the conventional method and the concentration method of the present invention.

FIG. 9 is a system diagram showing an apparatus for performing a conventional method for producing a high-concentration coal / water slurry.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Coarse crusher 12 High-concentration wet crusher 14 Coarse particle remover 16 Stirring mixer 18 Cooler 20 Water evaporator 22 Water evaporator 24 Stir and mixing tank

Claims (12)

(57) [Claims] 1. A method for producing a high-concentration coal / water slurry including a step of mixing coal, water and a dispersant, and a step of wet-milling coal, wherein the concentration of the coal / water slurry is 0.6 to 3.0 higher than a set concentration of the product coal / water slurry. Wet pulverization is performed at a low concentration in the range of weight%, and then, after adjusting the particle size, the retained heat of the coal / water slurry is concentrated as the heat source at least as a part of the heat source to the set concentration. Water slurry production method. 2. The method for producing a high-concentration coal / water slurry according to claim 1, wherein the wet-pulverization is performed, and then the particle size is adjusted to a particle size of 75 to 85% by weight of 200 mesh or less. 3. The coal / water slurry is concentrated by stirring the coal / water slurry in an open-top stirring tank and evaporating water by the retained heat of the coal / water slurry, and simultaneously cooling the coal / water slurry. The method for producing a high-concentration coal / water slurry according to claim 1 or 2. 4. Coal / water slurry is concentrated by stirring the coal / water slurry in an open-top stirring tank having a heating function and evaporating water by the added heat and the retained heat of the coal / water slurry. The method for producing a high-concentration coal / water slurry according to claim 1 or 2, which is performed. 5. A method of concentrating a coal / water slurry by sucking gas from above in a closed stirring tank and evaporating water by the retained heat of the coal / water slurry while reducing the pressure in the stirring tank. 3. The method for producing a high-concentration coal / water slurry according to 1 or 2. 6. The method for producing a high-concentration coal / water slurry according to claim 1, wherein the concentration of the coal / water slurry is performed by adding and mixing dry pulverized coal. 7. A high-concentration wet pulverizer for wet-pulverizing coal while mixing coal, water and a dispersant, and a coarse-particle remover for removing coarse particles in a coal-water slurry from the wet pulverizer;
A high-concentration coal / water slurry comprising a stirring / mixing machine for stirring and mixing the coal / water slurry from which coarse particles have been removed, and a cooler for cooling the stirred / mixed coal / water slurry to produce a product coal / water slurry. In the manufacturing apparatus, a moisture evaporator is provided between the coarse particle remover and the stirring mixer to evaporate the water in the coal / water slurry by the retained heat of the coal / water slurry to increase the concentration of the coal / water slurry. An apparatus for producing high-concentration coal / water slurry, which is provided. 8. A high-concentration wet pulverizer for wet pulverizing coal while mixing coal, water and a dispersant, a coarse particle remover for removing coarse particles in a coal / water slurry from the wet pulverizer,
A high-concentration coal / water slurry comprising a stirring / mixing machine for stirring and mixing the coal / water slurry from which coarse particles have been removed, and a cooler for cooling the stirred / mixed coal / water slurry to produce a product coal / water slurry. In the manufacturing equipment, between the agitating mixer and the cooler, the water in the coal / water slurry is evaporated by the retained heat of the
An apparatus for producing high-concentration coal / water slurry, comprising a water evaporator for increasing the concentration of water slurry. 9. The apparatus for producing a high-concentration coal / water slurry according to claim 7, wherein the water evaporator is an open-top stirring tank provided with a stirrer inside. 10. The high-concentration coal according to claim 7, wherein the moisture evaporator is a closed stirring tank provided with a stirrer inside.
Water slurry production equipment. 11. The apparatus for producing a high-concentration coal / water slurry according to claim 9, wherein the stirring tank is provided with a heating means. 12. A high-concentration wet pulverizer for wet-pulverizing coal while mixing coal, water and a dispersant, and a coarse-particle remover for removing coarse particles in a coal-water slurry from the wet pulverizer; A high-concentration coal / water slurry comprising a stirring / mixing machine for stirring and mixing the coal / water slurry from which coarse particles have been removed, and a cooler for cooling the stirred / mixed coal / water slurry to produce a product coal / water slurry. In the manufacturing apparatus, between the coarse particle remover and the stirring and mixing machine, a stirring and mixing tank for adding dry pulverized coal and stirring and mixing to increase the concentration of the coal / water slurry is provided. Concentration coal / water slurry production equipment.