Method for mixing black pellet solid fuel, method for transporting black pellet mixed fuel and black pellet solid fuel

Abstract

This black pellet solid fuel mixing method is used when storing or transporting black pellet solid fuel and has a mixing step in which black pellet solid fuel and coal that has a water content of at least 6% by mass are mixed such that the black pellet solid fuel and coal mixing ratio (black pellet solid fuel / coal) is 0.1–9.0 by mass ratio.

Description

[Technical Field]

[0001] The present invention relates to a method for mixing black pellet solid fuel, a black pellet mixed fuel, and a method for transporting black pellet solid fuel. [Background technology]

[0002] In recent years, biomass solid fuels have been considered as a way to reduce CO2 emissions, which are believed to be a cause of global warming. For example, Patent Document 1 discloses a method for producing a biomass solid fuel, which includes a step of mechanically compressing and dehydrating a biomass raw material containing wood.

[0003] Furthermore, development of solid fuel obtained by semi-carbonizing biomass solid fuel (hereinafter sometimes referred to as black pellet solid fuel or black pellets) is also underway. Although black pellets have a lower calorific value than coal, a representative solid fuel, they are expected to be used in the same way as coal. For example, Patent Document 2 discloses a black pellet and coal co-firing system. This black pellet and coal co-firing system includes a coal pulverizer that pulverizes coal to obtain coal powder, a black pellet pulverizer that pulverizes black pellets to obtain black pellet powder, and a boiler furnace to which the coal powder and black pellet powder are supplied, and is characterized in that, during pulverization in the black pellet pulverizer, additives are added to the black pellets while they are mixed and pulverized. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-095685 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-132602 Summary of the Invention [Problem to be solved by the invention]

[0005] However, black pellets have the problem of scattering dust during storage and transportation, which not only worsens the working environment but also reduces work efficiency and may ignite the dust and cause a fire. The object of the present invention is to provide a method for mixing black pellet solid fuel, a black pellet mixed fuel, and a method for transporting black pellet solid fuel that can suppress the scattering of dust when storing or transporting black pellet solid fuel. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided a method for mixing black pellet solid fuel used when storing or transporting black pellet solid fuel, the method comprising a mixing step of mixing the black pellet solid fuel with coal having a moisture content of 6% by mass or more so that the mixing ratio of the black pellet solid fuel to the coal (the black pellet solid fuel / the coal) is 0.1 or more and 9.0 or less by mass.

[0007] In the method for mixing black pellet solid fuel according to one aspect of the present invention, the mixing step is preferably a step of adding the coal to the black pellet solid fuel.

[0008] In one embodiment of the present invention, in the method for mixing black pellet solid fuel, it is preferable that the black pellet solid fuel is at least one of black pellet solid fuel stored in a storage container or storage area, and black pellet solid fuel transported by a transport means.

[0009] In one embodiment of the present invention, in the method for mixing black pellet solid fuel, it is preferable that the mixing process be carried out at least at one stage before storing the black pellet solid fuel in the storage container or the storage area, or before transporting it by the transport means.

[0010] In one embodiment of the present invention, in the method for mixing black pellet solid fuel, it is preferable that the mixing process be carried out at least at one stage after the black pellet solid fuel is stored in the storage container or storage area, or during the transportation by the transportation means.

[0011] In the black pellet solid fuel mixing method according to one aspect of the present invention, the transport means is preferably at least one of an unloader, an elevator, a car, a conveyor, a belt feeder, and a ship.

[0012] In the method for mixing black pellet solid fuel according to one embodiment of the present invention, it is preferable that the mixing step mixes the black pellet solid fuel and the coal by alternately stacking the black pellet solid fuel and the coal.

[0013] In the method for mixing black pellet solid fuel according to one aspect of the present invention, the coal is preferably bituminous coal, subbituminous coal, or lignite.

[0014] According to one aspect of the present invention, there is provided a black pellet mixed fuel, which is a mixture of the black pellet solid fuel and the coal, obtained by carrying out the black pellet solid fuel mixing method according to the above-mentioned one aspect of the present invention.

[0015] According to one aspect of the present invention, there is provided a method for transporting black pellet solid fuel, comprising: a mixing step of mixing black pellet solid fuel with coal having a moisture content of 6% by mass or more so that the mixing ratio of the black pellet solid fuel to the coal (the black pellet solid fuel / the coal) is 0.1 or more and 9.0 or less by mass; and a transporting step of leaving the mixture of the black pellet solid fuel and the coal obtained in the mixing step to stand for one hour or more, and then transporting the mixture from the location where the mixing step was performed to another location.

[0016] According to one aspect of the present invention, a method for mixing black pellet solid fuel, a method for transporting black pellet mixed fuel, and a method for transporting black pellet solid fuel can be provided that can suppress the scattering of dust when storing or transporting black pellet solid fuel. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 3 is a diagram illustrating one aspect of a mixing step according to the first embodiment. [Figure 2] FIG. 3 is a diagram illustrating one aspect of a mixing step according to the first embodiment. [Figure 3] FIG. 3 is a diagram illustrating one aspect of a mixing step according to the first embodiment. [Figure 4] FIG. 3 is a diagram illustrating one aspect of a mixing step according to the first embodiment. [Figure 5] FIG. 3 is a diagram illustrating one aspect of a mixing step according to the first embodiment. [Figure 6] FIG. 3 is a diagram illustrating one aspect of a mixing step according to the first embodiment. [Figure 7] FIG. 3 is a diagram illustrating one aspect of a mixing step according to the first embodiment. [Figure 8] FIG. 3 is a diagram illustrating one aspect of a mixing step according to the first embodiment. [Figure 9] 2 is a graph showing the results of evaluation of dust scattering properties of Examples 1 to 5 and Comparative Examples 1 to 3. [Figure 10] 1 is a graph showing the results of the dust scattering evaluation of Examples 1 to 10. [Figure 11] 1 is a graph showing the moisture content of coal contained in black pellet mixed fuels after evaluation of dust scattering properties in Examples 1 to 10. [Figure 12] 1 is a graph showing the moisture content of black pellets contained in black pellet mixed fuels after evaluation of dust scattering properties in Examples 1 to 10. DETAILED DESCRIPTION OF THE INVENTION

[0018] In this specification, black pellet solid fuel or black pellets refers to a solid fuel obtained by semi-carbonizing a biomass solid fuel (hereinafter sometimes referred to as white pellets) made from biomass raw materials.

[0019] [First embodiment] (Black pellet solid fuel mixing method) The mixing method for black pellet solid fuel according to this embodiment (hereinafter also referred to as "the mixing method of this embodiment") is a mixing method for black pellet solid fuel used when storing or transporting black pellet solid fuel, and includes a mixing step of mixing the black pellet solid fuel with coal having a moisture content of 6% by mass or more so that the mixing ratio between the black pellet solid fuel and the coal (the black pellet solid fuel / the coal) is 0.1 or more and 9.0 or less by mass. According to the mixing method of this embodiment, by performing a mixing step in which black pellet solid fuel is mixed with coal whose moisture content is adjusted to a predetermined range (moisture content of 6% by mass or more), moisture retained on the coal surface is transferred from the coal to the black pellets, and the black pellet surface becomes moderately wet. As a result, dust scattering from the black pellet solid fuel is suppressed. Furthermore, according to the mixing method of this embodiment, dust scattering from the black pellet solid fuel is suppressed, thereby suppressing a deterioration in the working environment and a decrease in work efficiency. Furthermore, according to the mixing method of this embodiment, dust scattering from the black pellet solid fuel is suppressed, thereby suppressing ignition of the dust and the occurrence of fires. In the mixing method of this embodiment, the coal whose moisture content has been adjusted to a predetermined range is thought to function as a dust dispersion inhibitor for the black pellet solid fuel.

[0020] In the mixing method of this embodiment, if the moisture content of the coal is 6% by mass or more, the function as a dust scattering prevention agent is exhibited. The moisture content of the coal is preferably 7% by mass or more, more preferably 8% by mass or more, and even more preferably 10% by mass or more. The higher the moisture content of the coal, the greater the dust scattering prevention effect, so there is no upper limit to the moisture content of the coal, but from the perspective of ease of handling, it is preferably 50% by mass or less, and more preferably 40% by mass or less. Examples of methods for adjusting the moisture content of coal to fall within a predetermined range include immersing the coal in water, spraying water onto the coal, storing the coal in a humidified space, and selecting coal with a moisture content of 6% by mass or more. Coal with a moisture content of 6% by mass or more may be coal whose moisture content (total moisture) itself is 6% by mass or more, but is preferably coal whose moisture content has been adjusted by adding water. The moisture content of coal whose moisture content has been adjusted by adding water refers to a value calculated by taking into consideration both the amount of moisture contained in the coal itself and the amount of moisture added to the coal. For example, when 10 parts by mass of water is added to 100 parts by mass of coal with a moisture content (total moisture) of 5% by mass, the moisture content of the coal is calculated to be 13.6% by mass ((5 + 10) / (100 + 10)) × 100 ≒ 13.6). The amount of moisture contained in the coal itself (total moisture) can be measured in accordance with JIS M8820 (2000).

[0021] In the mixing method of this embodiment, when the mixing ratio of the black pellet solid fuel to the coal (the black pellet solid fuel / the coal) is 0.1 or more in mass ratio, the moisture on the surface of the coal is easily transferred to the black pellet solid fuel. There is no particular upper limit on the mass ratio of the mixture ratio of black pellet solid fuel to coal (said black pellet solid fuel / said coal), but considering use in combustion furnaces such as coal boilers, the mixture ratio of black pellet solid fuel to coal (said black pellet solid fuel / said coal) must be 9.0 or less in mass ratio. When the mixing ratio (black pellet solid fuel / coal) is 9.0 or less by mass, the moisture on the surface of the coal is transferred to the black pellets, and the dust scattering prevention effect is easily achieved. The mixing ratio (black pellet solid fuel / coal) is preferably higher because the moisture on the surface of the coal is more easily transferred to the black pellets. Therefore, the mixing ratio (black pellet solid fuel / coal) is preferably 0.1 or more and 1.0 or less, more preferably 0.1 or more and 0.5 or less, in terms of mass ratio.

[0022] Here, the mixing ratio of black pellet solid fuel to coal means the mixing ratio between the black pellet solid fuel to be mixed and the coal to be mixed with the black pellet solid fuel (the black pellet solid fuel to be mixed / the coal to be mixed with the black pellet solid fuel). The coal to be mixed is coal with a moisture content of 6% by mass or more (preferably coal that has been hydrated to have a moisture content of 6% by mass or more). For example, when coal is mixed with all of the black pellet solid fuel stored in a storage yard, the black pellet solid fuel to be mixed is all of the black pellet solid fuel stored in the storage yard. Similarly, when coal is mixed with all of the black pellet solid fuel being transported by a belt conveyor, the black pellet solid fuel to be mixed is all of the black pellet solid fuel being transported by the belt conveyor. Furthermore, when coal is mixed with black pellet solid fuel being transported by a specific belt conveyor (for example, a belt conveyor installed in a location where dust is likely to scatter), the black pellet solid fuel to be mixed is the black pellet solid fuel being transported by the specific belt conveyor. The mass of the black pellet solid fuel being transported by the belt conveyor is calculated from the transport rate (kg / min) of the belt conveyor. Furthermore, for example, when coal is mixed locally with black pellet solid fuel located in a place where dust scattering is expected (hereinafter referred to as area X), the black pellet solid fuel to be mixed is the black pellet solid fuel located in area X.

[0023] In the mixing method of the present embodiment, the mixing step is preferably a step of adding the coal (coal having a moisture content of 6% by mass or more) to the black pellet solid fuel. In the mixing method of the present embodiment, the mixing step may be a step of adding the coal (coal having a moisture content of 6% by mass or more) to the black pellet solid fuel in multiple batches. In this case, the coal in the mixing ratio (the black pellet solid fuel / the coal) is the total amount (total mass) of the coal added in multiple batches.

[0024] The black pellet solid fuel used in the mixing method of this embodiment is preferably at least one of black pellet solid fuel stored in a storage container or storage area, and black pellet solid fuel transported by a transport means. Examples of storage containers include silos, hoppers, bins, and ship holds. Storage sites include, for example, locations where black pellet solid fuel is stored (e.g., piled and mounded) in outdoor locations or indoor covered locations (e.g., dome-type and warehouse-type locations). The transport means is a means for transporting the black pellet solid fuel, and is preferably at least one of an unloader, an elevator, a car, a conveyor, a belt feeder, and a ship. The type of conveyor is not particularly limited, and examples thereof include belt conveyors, flow conveyors, and pipe conveyors. Examples of vehicles include various trucks, bulldozers, and power shovels.

[0025] The storage container, storage area, and transport means may be installed indoors or outdoors, and are preferably used in any of the following processes. The process of black pellet solid fuel manufactured in the black pellets' place of origin until it arrives at the loading port. The process of black pellet solid fuel from the loading port to the arrival at the discharging port. Black pellet solid fuel being unloaded after arriving at the port of discharge. The process of black pellet solid fuel arriving at the port of discharge, being unloaded, and arriving at its destination (e.g., various power plants, steel mills, factories, etc.). The process of domestically produced black pellet solid fuel until it reaches its destination (e.g., various power plants, steel mills, and factories). The process of black pellet solid fuel once it arrives at its destination until it is consumed (e.g., burned).

[0026] In the mixing method of this embodiment, the mixing step is preferably carried out at least at any stage before the black pellet solid fuel is stored in a storage container or storage area, or before it is transported by a transport means. This makes it possible to prevent dust from flying even before the black pellet solid fuel is stored.

[0027] In the mixing method of this embodiment, it is also preferable that the mixing step is carried out at least at any stage after the black pellet solid fuel is stored in a storage container or storage area, or during transportation by a transportation means. For example, if the black pellet solid fuel is stored in a storage area and then exposed to an environment where the black pellet solid fuel is likely to scatter (such as a low humidity environment), the mixing process can prevent dust from scattering. Also, the mixing process can be performed in a location where the black pellet solid fuel is expected to scatter, thereby preventing dust from scattering.

[0028] In the mixing step, the mixing means for mixing the black pellet solid fuel with the coal is not particularly limited, but examples thereof include a power shovel, a truck, a belt conveyor, a screen, a pulverizer, a coal mixer, and a shovel.

[0029] The "mixing" in the mixing process does not necessarily mean that the black pellet solid fuel and coal are mixed uniformly, but rather that coal is present in the black pellet solid fuel. Therefore, the "mixing" in the mixing process also includes, for example, a state in which the black pellet solid fuel and coal are simply stacked, a state in which the black pellet solid fuel and coal are stacked in alternating layers, and a state in which coal is added to the black pellet solid fuel being transported by various conveyors.

[0030] Specific examples of "mixing" in the mixing step include mixing by alternately stacking black pellet solid fuel and coal using a backhoe, mixing by adding coal to a belt conveyor while the black pellet solid fuel is being transported on the belt conveyor, mixing by passing the black pellet solid fuel and coal through a screen, mixing the black pellet solid fuel and coal while pulverizing them using a pulverizer, mixing the black pellet solid fuel and coal using a coal blender, and manually mixing using a shovel or the like.

[0031] <Preferred embodiment of the mixing step> Preferred embodiments 1 to 8 of the mixing step will be described with reference to Figures 1 to 8. However, the mixing step is not limited to these embodiments. The coals shown in Figures 1 to 8 all have moisture contents adjusted to a predetermined range (6% by mass or more).

[0032] (Aspect 1) FIG. 1 is a diagram illustrating a first embodiment of the mixing step. 1 shows a storage facility 100. The storage facility 100 includes a storage facility where black pellets are piled up (hereinafter also referred to as the BP storage facility 10), a mixture storage facility 20A where a mixture of black pellets and coal (black pellet mixed fuel) is piled up, a coal storage facility 30 where coal is piled up, a shovel 1a that travels back and forth between the BP storage facility 10 and the mixture storage facility 20A, and a shovel 1b that travels back and forth between the mixture storage facility 20A and the coal storage facility 30. In the case of the first embodiment, the mixing step is carried out using the storage facility 100 as follows. Excavator 1a transports some of the black pellets from BP storage site 10 to location 20a where mixture storage site 20A will be constructed, and discharges the black pellets at location 20a. Excavator 1b transports some of the coal from coal storage site 30 to location 20a, and discharges the coal at location 20a. In this way, the black pellets and coal are mixed by piling them up in any order (mixing process). However, when piling up the black pellets and coal, the number of trips of each excavator and the amount of material being transported are adjusted, for example, so that the mixture ratio of the black pellets to the coal (black pellets / coal) is within a specified range (mass ratio of 0.1 to 1.0). As a result of the above, a mixture storage field 20A in which black pellet mixed fuel is piled up is obtained. The mixture storage field 20A may be used as a storage field for the black pellet mixed fuel as is, or a part or all of the black pellet mixed fuel in the mixture storage field 20A may be transported and stored in another storage field or storage container (for example, a silo or a hopper). When transferring some or all of the black pellet mixed fuel in the mixture storage area 20A to another storage area or storage container, it is preferable to leave the black pellet mixed fuel piled up in the mixture storage area 20A for at least one hour before transferring it, which can further reduce the scattering of dust. The mixing means in the first embodiment are excavators 1a and 1b.

[0033] (Aspect 2) FIG. 2 is a diagram illustrating a second embodiment of the mixing step. Fig. 2 shows a storage facility 100 similar to that shown in Fig. 1. The mixing process of Mode 2 differs from Mode 1 in the method of piling up the black pellets and coal. Other than this, Mode 2 is similar to Mode 1, so below, differences from Mode 1 will be described, and commonalities will be omitted. In the case of the second embodiment, the black pellets and coal are mixed by alternately stacking them using the excavators 1a and 1b (mixing step). Here, "alternately stacking" is not limited to stacking the black pellets, coal, black pellets, coal, ... as shown in Fig. 2, but also includes stacking in order, for example, black pellets, black pellets, coal, black pellets, black pellets, coal, coal, ... so that layers of stacked black pellets and layers of stacked coal are alternately formed. In this case, the thickness of each layer formed is not limited. As a result of the above, a mixture reservoir 20B is obtained in which black pellets and coal are piled up in alternate layers.

[0034] (Aspect 3) FIG. 3 is a diagram illustrating a third embodiment of the mixing step. 3 shows a storage facility 101. The storage facility 101 includes a BP storage site 10 where black pellets are piled up, a truck 1x with a mixture of black pellets and coal (black pellet mixed fuel 21 in the case of FIG. 3) loaded on its loading platform, a coal storage site 30 where coal is piled up, a shovel 1a that travels back and forth between the BP storage site 10 and the truck 1x, and a shovel 1b that travels back and forth between the truck 1x and the coal storage site 30. In the case of the third embodiment, the mixing step is carried out using the storage facility 101 as follows. Excavator 1a carries some of the black pellets in BP storage site 10 to the loading platform of truck 1x and discharges the coal in the loading platform. Excavator 1b carries some of the coal in coal storage site 30 to the loading platform of truck 1x and discharges the coal in the loading platform. In this way, the black pellets and coal are mixed by piling them up in any order on the loading platform of truck 1x (mixing process). However, when stacking the black pellets and coal onto the bed of truck 1x, the number of trips and amount of transportation of each excavator are adjusted, for example, so that the mixture ratio of black pellets to coal (black pellets / coal) falls within a specified range. As a result of the above, the black pellet mixed fuel 21 is obtained and piled up on the loading platform of the truck 1x. The obtained black pellet mixed fuel 21 is transported to the destination by the truck 1x. When transporting the black pellet mixed fuel 21 to the destination by truck 1x, it is preferable to leave the black pellet mixed fuel 21 stacked on the bed of truck 1x for at least one hour before transporting, which can further prevent dust from scattering. The mixing means in the third embodiment are excavators 1a and 1b.

[0035] (Aspect 4) FIG. 4 is a diagram illustrating a fourth embodiment of the mixing step. 4 shows the conveying equipment 102. The conveying equipment 102 includes a belt conveyor 2a that conveys the black pellets 12, a belt conveyor 2b that conveys the coal 32, a belt conveyor 2c that is located at the transfer point between the belt conveyors 2a and 2b and where the black pellets 12 and the coal 32 join, and a container 42 into which the black pellets 12 and the coal 32 are discharged. The container 42 also serves as a storage container. In the case of the fourth embodiment, the mixing step is carried out using the conveying equipment 102 as follows. The belt conveyor 2a discharges the black pellets 12 onto the belt conveyor 2c, and the belt conveyor 2b discharges the coal 32 onto the belt conveyor 2c. In this way, the black pellets 12 and the coal 32 are mixed by discharging them onto the belt conveyor 2c (mixing process). However, when the black pellets 12 and coal 32 are discharged onto the belt conveyor 2c, the discharge amounts of the black pellets 12 and coal 32 from each belt conveyor are adjusted so that the mixing ratio of the black pellets 12 and coal 32 (black pellets 12 / coal 32) is within a predetermined range. The mixture of black pellets 12 and coal 32 (black pellet mixed fuel) on the belt conveyor 2c is discharged into a container 42, and black pellet mixed fuel 22 is obtained. Examples of the container 42 include a silo, a hopper, a bin, etc. The same applies to the containers 43 and 44 in FIG. The mixing means in the fourth embodiment are belt conveyors 2a, 2b, and 2c.

[0036] (Aspect 5) FIG. 5 is a diagram illustrating a fifth embodiment of the mixing step. 5 shows the conveying equipment 103. The conveying equipment 103 includes a belt conveyor 2d for conveying the black pellets 12, a belt conveyor 2e for conveying the coal 32, a screen 3, a belt conveyor 2f for conveying the mixture of the black pellets 12 and the coal 32 (black pellet mixed fuel 23) that has passed through the screen 3, and a container 42 into which the black pellet mixed fuel 23 is discharged. The container 42 also serves as a storage container. In the case of the fifth embodiment, the mixing step is carried out using the conveying equipment 103 as follows. The belt conveyor 2d discharges the black pellets 12 onto the screen 3, and the belt conveyor 2e discharges the coal 32 onto the screen 3. In this way, the black pellets 12 and the coal 32 are mixed by passing them through the screen 3 (mixing process). However, when the black pellets 12 and coal 32 are passed through the screen 3, the discharge amounts of the black pellets 12 and coal 32 from each belt conveyor are adjusted so that the mixing ratio of the black pellets 12 to the coal 32 (black pellets 12 / coal 32) falls within a predetermined range. The black pellet mixed fuel 23 obtained by passing through the screen 3 is discharged from the belt conveyor 2f into a container 42. The mixing means in the fifth embodiment are the belt conveyors 2 d , 2 e , and 2 f and the screen 3 .

[0037] (Aspect 6) FIG. 6 is a diagram illustrating a sixth embodiment of the mixing step. 6 shows a conveying facility 104. The mixing step of the sixth embodiment is similar to the fifth embodiment except that a crusher 4 is used instead of the screen 3. Therefore, the following description will focus on the differences from the fifth embodiment, and the commonalities will be omitted. In the case of the sixth embodiment, the black pellets 12 and the coal 32 are mixed by passing them through the pulverizer 4 (mixing step). In the container 42, the black pellet mixed fuel 24 is obtained. The mixing means in the sixth embodiment are the belt conveyors 2d, 2e, and 2f and the crusher 4.

[0038] (Aspect 7) FIG. 7 is a diagram illustrating embodiment 7 of the mixing step. 7 shows the conveying equipment 105. The conveying equipment 105 includes a belt conveyor 2j for conveying the black pellets 12, a belt conveyor 2k for conveying the coal 32, and a container 42 into which the black pellets 12 and the coal 32 are discharged. The container 42 also serves as a storage container. In the case of the seventh embodiment, the mixing step is carried out using the conveying equipment 105 as follows. The belt conveyor 2j discharges the black pellets 12 into the container 42, and the belt conveyor 2k discharges the coal 32 into the container 42. In this way, the black pellets 12 and the coal 32 are mixed (mixing step). However, when the black pellets 12 and the coal 32 are discharged into the container 42, the discharge amounts of the black pellets 12 and the coal 32 from each belt conveyor are adjusted so that the mixture ratio of the black pellets 12 to the coal 32 (black pellets 12 / coal 32) falls within a predetermined range. In the container 42, black pellet mixed fuel 25 is obtained. The mixing means in the seventh embodiment are belt conveyors 2j and 2k.

[0039] (Aspect 8) FIG. 8 is a diagram illustrating an eighth embodiment of the mixing step. 8 shows the conveying equipment 106. The conveying equipment 106 includes a belt conveyor 2m for conveying the black pellets 12, a belt conveyor 2n for conveying the coal 32, a container 43 into which the mixture of the black pellets 12 and the coal 32 (black pellet mixed fuel 26) is discharged, three belt conveyors 2p, 2q, and 2r for sequentially conveying the black pellet mixed fuel 26 discharged from the container 43, another belt conveyor 2x for adding coal 32A onto the belt conveyor 2r, and a container 44. The containers 43 and 44 serve as storage containers. In the case of the eighth embodiment, the mixing step is carried out using the conveying equipment 105, for example, as follows. The mixing step of the eighth embodiment is an example in which coal having a moisture content of 6% by mass or more is added in two batches to the black pellets 12. Specifically, after the coal 32 is added to the black pellets 12, the coal 32A is further added. Both the coal 32 and the coal 32A have moisture contents adjusted to 6% by mass or more. Belt conveyor 2m discharges black pellets 12 into container 43, and belt conveyor 2n discharges coal 32 into container 43. The black pellet mixed fuel 26 obtained in container 43 travels along three belt conveyors 2p, 2q, and 2r, and is discharged onto the third belt conveyor 2r, where coal 32A is added from another belt conveyor 2x, and the black pellet mixed fuel 26A is obtained in container 44 (mixing process). In this way, the black pellets 12, coal 32, and coal 32A are mixed, and black pellet mixed fuel 26A is obtained in container 44. The coal 32 and coal 32A may be the same type or different types. The mixing ratio of black pellets 12 to coal (coal 32 + coal 32A) in the black pellet mixed fuel 26A in the container 44 is adjusted to be 0.1 or more and 9.0 or less (mass ratio) by adjusting the discharge amounts of black pellets 12, coal 32, and coal 32A from each belt conveyor. The mixing means in the eighth embodiment are the belt conveyors 2m, 2n, 2p, 2q, and 2r and another belt conveyor 2x.

[0040] The coal used in the blending method of this embodiment is preferably bituminous coal, subbituminous coal, or lignite. The coal is preferably in powder or granular form from the viewpoint of ease of blending with the black pellet solid fuel. The size of the coal is not particularly limited, but a particle size of 50 mm or less is preferred. The properties of bituminous coal, subbituminous coal, and lignite are as follows: Bituminous coal: Coal with a gross calorific value of 8,100 kcal / kg or more but less than 8,400 kcal / kg on an ash-free basis. Subbituminous coal: Coal with a gross calorific value of 7,300 kcal / kg or more but less than 8,100 kcal / kg on an ash-free basis. Lignite: Coal with a gross calorific value of 5,800 kcal / kg or more but less than 7,300 kcal / kg on an ash-free basis.

[0041] The black pellet solid fuel used in the mixing method of this embodiment may be in the form of, for example, pellets or chips. Pellets include briquettes. While the size of the pellets is not particularly limited, they are typically cylindrical, preferably having a diameter of 5 mm to 10 mm and a length of 5 mm to 50 mm. While the size of the chips is not particularly limited, their major axis diameter is preferably 50 mm or less. In addition to the black pellets, the black pellet solid fuel may contain, as necessary, a binder resin, an additive, etc. Examples of the additive include an adhesive, an antioxidant, etc.

[0042] Second Embodiment (Black pellet mixed fuel) The black pellet mixed fuel of the second embodiment is obtained by the mixing method of the first embodiment. Therefore, the black pellet mixed fuel of the second embodiment is a black pellet mixed fuel in which dust scattering is suppressed, and can be used as fuel as is.

[0043] Third Embodiment [Method for transporting black pellet solid fuel] A third embodiment of the method for transporting black pellet solid fuel (hereinafter also referred to as the "third embodiment of the transport method") includes a mixing process for mixing black pellet solid fuel with coal having a moisture content of 6% by mass or more so that the mixing ratio of the black pellet solid fuel to the coal is 0.1 or more and 9.0 or less by mass (the black pellet solid fuel / the coal), and a transporting process for leaving the mixture of the black pellet solid fuel and the coal obtained in the mixing process to stand for one hour or more, and then transporting the mixture from the location where the mixing process was performed to another location. That is, the transportation method of the third embodiment is a transportation method in which the mixture of black pellet solid fuel and coal (i.e., black pellet mixed fuel) obtained by the mixing method of the first embodiment is left to stand for more than one hour and then transported to another location. In this specification, "leaving for one hour or more" refers to a standing time of one hour or more from the end of the mixing process to the start of transportation. For example, in the case of the above-mentioned embodiment 1, this refers to a time (standing time) of one hour or more from the time when the mixture storage field 20A is constructed (the end of the mixing process) to the time when the black pellet mixed fuel is moved toward a destination (e.g., another storage field or storage container, etc.). In the case of the above-mentioned embodiment 3, this refers to a time (standing time) of one hour or more from the time when the black pellet mixed fuel 21 is completely piled up on the bed of the truck 1x (the end of the mixing process) to the time when the truck 1x departs toward a destination (e.g., another storage field or storage container, etc.).

[0044] <Mixing process> The mixing step in the third embodiment is synonymous with the mixing step in the first embodiment. Therefore, the preferred ranges of the moisture content of the coal and the mixing ratio of the black pellet solid fuel to the coal (the black pellet solid fuel / the coal) in the mixing step of the third embodiment are the same as those in the first embodiment.

[0045] <Transportation process> Specifically, the transporting process is a process in which the black pellet mixed fuel obtained in the mixing process is left to stand for at least one hour, and then the black pellet mixed fuel is transported from the location where the mixing process was carried out to another location. By carrying out the mixing process, the surface of the black pellet solid fuel becomes moderately wet, as in the first embodiment. In the third embodiment, the black pellet solid fuel with a moderately wet surface is left standing for an additional hour or more, which is thought to ensure time for the moisture held on the coal surface to move to the black pellet surface. According to the transportation method of the third embodiment, the black pellet solid fuel is transported in this surface condition, which further reduces the scattering of dust. This further reduces the deterioration of the working environment and the decrease in work efficiency. Furthermore, the ignition of the dust and the occurrence of fires are further reduced. The time for which the mixture of black pellet solid fuel and coal is allowed to stand is preferably 2 hours or more, more preferably 3 hours or more, and even more preferably 4 hours or more. The upper limit of the time for standing is preferably 24 hours or less, from the viewpoint of keeping the surfaces of the black pellets in a moderately wet state. The transport means may be, for example, the transport means exemplified in the first embodiment.

[0046] Other Embodiments The present invention is not limited to the above-described embodiment, and any modifications and improvements that can achieve the object of the present invention are included in the present invention. [Example]

[0047] Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0048] Table 1 shows the properties of the black pellets used as raw materials in the examples and comparative examples. In Table 1, black pellets are solid fuels made by semi-carbonizing (heating in an oxygen-free environment) white pellets made from biomass material (rubber trees).

[0049] [Table 1]

[0050] Explanation of Table 1 The total moisture content of black pellets is measured in accordance with ISO 18134-3. Proximate analysis values ​​were measured in accordance with JIS M8812 (2004). Of the elemental analysis values, carbon, hydrogen, nitrogen, and sulfur were measured in accordance with JIS M8819 (1997), and oxygen was calculated from other analytical values ​​in accordance with JIS M8813 (2004). The higher heating value is a value measured in accordance with JIS M8814 (2003). The fuel ratio is "fixed carbon / volatiles." "db" and "DB" refer to a dry basis. "AR" indicates arrival base. "ad" and "AD" refer to air dry basis. "daf" indicates dry ash-free basis. "Ash" indicates ash-based. HGI is the Hardgrove Crushability Index.

[0051] Example 1 Black pellets (raw material for black pellets: rubber wood) with a moisture content of 7.2 mass% were prepared as the black pellet solid fuel. Next, the black pellets were mixed with coal (Mount Owen coal: produced in Australia, average particle size 5 mm) whose moisture content had been adjusted to 10% by mass, so that the mixing ratio of the black pellets to the coal was 10 / 90 by mass (black pellets / coal), and 50 kg of black pellet mixed fuel of Example 1 was produced. The moisture content of the coal was adjusted to 10% by mass by sprinkling tap water over the coal using a watering can and then mixing the coal with a shovel. Specifically, the moisture content of the coal was adjusted to 10% by mass by adding 2.2 parts by mass of water to 100 parts by mass of coal, taking into account the amount of moisture contained in the coal (Mount Owen coal) itself (total moisture (8 wt%)). The calculation formula is as follows: Moisture content of coal [mass%] = ((8.0 + 2.2) / (100 + 2.2)) × 100 ≒ 10 The black pellet mixed fuel of Example 1 was used for the evaluation of dust scattering properties immediately after preparation (no rest time after mixing).

[0052] Examples 2 to 5 The black pellet mixed fuels of Examples 2 to 5 were produced in the same manner as Example 1, except that the mixing ratio of the black pellets to the coal and the moisture content of the coal were changed to the requirements shown in Table 2. As in Example 1, the black pellet mixed fuels of Examples 2 to 5 were used for the evaluation of dust scattering properties immediately after they were produced.

[0053] Example 6 The black pellet mixed fuel of Example 6 was prepared in the same manner as in Example 1. The black pellet mixed fuel of Example 6 was filled into two pails (inner diameter 29.5 cm, height 38 cm), and after covering them with lids to prevent moisture evaporation, the pails were left standing at room temperature (25°C) for 4 hours (standing time: 4 hours). The black pellet mixed fuel after standing was used to evaluate dust scattering properties.

[0054] Examples 7 to 10 The black pellet mixed fuels of Examples 7 to 10 were produced in the same manner as in Example 1, except that the mixing ratio of the black pellets to the coal and the moisture content of the coal were changed to the requirements shown in Table 2. The black pellet mixed fuels of Examples 7 to 10 were filled into two pails and left to stand for 4 hours (standing time: 4 hours) in the same manner and under the same conditions as in Example 6. The black pellet mixed fuels after standing were used to evaluate dust scattering properties.

[0055] Comparative Example 1 Coal with a moisture content adjusted to 10 mass % was used as the pure coal fuel in Comparative Example 1.

[0056] Comparative Example 2 Coal having a moisture content of 8.0 mass % (total moisture) was used as the coal fuel of Comparative Example 2.

[0057] Comparative Example 3 Black pellets with a moisture content of 7.2 mass % (total moisture) were used as the black pellet plain fuel of Comparative Example 3 (hereinafter referred to as BP plain fuel).

[0058] 〔evaluation〕 (Dust scattering) Using a dust tester measuring 190 cm high x 90 cm wide x 62 cm deep, dust scattering was evaluated in the following manner. The results are shown in Figures 9 and 10. A cylindrical member with a tapered section (inner diameter (hole diameter) at the tip of the tapered section: 12 cm, inner diameter of the cylindrical section: 45 cm) was installed on top of the dust tester. The distance between the tip of the tapered section and the bottom of the dust tester was 155 cm. A digital dust meter was also installed on the bottom of the dust tester. Details of the digital dust meter are described below. The tip of the tapered section was blocked with a removable plate, and a sample of the black pellet mixed fuel of each Example (two pails' worth) or the plain fuel of each Comparative Example (two pails' worth) was introduced through the sample inlet provided at the top of the cylindrical member. The blocking plate was then removed, and the sample was allowed to fall naturally from the tip of the tapered section of the cylindrical member into the dust tester for 10 seconds. At the same time, the digital dust meter was turned on and the dust count was measured. The degree of dust scattering was also checked visually. Cases where almost no dust was scattered were rated "A", and cases where a large amount of dust was scattered were rated "B".

[0059] Digital dust meter: Shibata Scientific Co., Ltd., LD-3K2 model Measurement principle: Light scattering method Light source: Laser diode

[0060] (Moisture content of black pellets and coal after dust dispersion evaluation) After the evaluation of dust scattering, 50 g of the black pellet mixed fuel of each example was sampled after gravity falling, and the moisture content of the black pellets and the moisture content of the coal were measured. The results are shown in Figures 11 and 12. The moisture content (total moisture) of the black pellets was measured in accordance with ISO 18134-3. The moisture content (total moisture) of the coal was measured in accordance with JIS M8820 (2000).

[0061] [Table 2]

[0062] Explanation of Table 2 BP stands for black pellets. AR represents a sample of the arrival state.

[0063] 〔result〕 FIG. 9 shows the results of the dust scattering evaluation for Examples 1 to 5 and Comparative Examples 1 to 3. The black pellet mixed fuels of Examples 1 to 5 obtained by mixing black pellets with coal and the coal only fuels of Comparative Examples 1 and 2 showed a significant reduction in dust scattering compared to the BP only fuel of Comparative Example 3. FIG. 10 shows the results of the dust scattering evaluation for Examples 1 to 10. The black pellet mixed fuels of Examples 6 to 10, which were stored (left to stand) for 4 hours and then evaluated for dust scattering, showed even greater reductions in dust scattering than Examples 1 to 5, which were evaluated for dust scattering immediately without being left to stand.

[0064] FIG. 11 shows the moisture content of the coal contained in the black pellet mixed fuel after the dust scattering evaluation of Examples 1 to 10. In Examples 6 to 10, which were stored (left to stand) for 4 hours and then evaluated for dust scattering properties, the moisture content of the coal contained in the black pellet mixed fuel was reduced compared to before the evaluation. On the other hand, in Examples 1 to 5 in which the dust scattering property was evaluated immediately without being left to stand, the moisture content of the coal contained in the black pellet mixed fuel did not change compared to before the evaluation.

[0065] FIG. 12 shows the moisture content of the black pellets contained in the black pellet mixed fuels of Examples 1 to 10 after the dust scattering property evaluation. In Examples 6 to 10, which were stored (left to stand) for 4 hours and then evaluated for dust scattering properties, the moisture content of the black pellets contained in the black pellet mixed fuel increased compared to before the evaluation. On the other hand, in Examples 1 to 5 in which the dust scattering property was evaluated immediately without being left to stand, the moisture content of the black pellets contained in the black pellet mixed fuel did not change compared to before the evaluation. From the above, it was confirmed that after obtaining the black pellet mixed fuel, by leaving it to stand for a certain period of time, the moisture held on the coal surface migrates from the coal to the black pellets. Therefore, it is believed that black pellet mixed fuel obtained by mixing black pellets with coal whose moisture content has been adjusted to a predetermined range can be more effectively prevented from scattering dust by being left to stand for a certain period of time before being transported. [Industrial Applicability]

[0066] The present invention can suppress the scattering of dust when storing or transporting black pellet solid fuel, and can therefore be effectively used during the transportation process from the time the black pellet solid fuel is unloaded to its destination (power plants, steel mills, factories, etc.), as well as within the destination's premises. [Explanation of symbols]

[0067] 1a, 1b... Excavator, 1x... Truck, 2a, 2b, 2c, 2d, 2e, 2f, 2j, 2k, 2m, 2n, 2p, 2q, 2r, 2x... Belt conveyor, 3... Screen, 4... Crusher, 10... BP storage area, 12... Black pellets, 20A, 20B... Mixed storage area, 20a... Location, 21, 22, 23, 24, 25, 26, 26A... Black pellet mixed fuel, 30... Coal storage area, 32, 32A... Coal, 42, 43, 44... Container, 100, 101... Storage equipment, 102, 103, 104, 105, 106... Conveying equipment.

Claims

1. A method for mixing black pellet solid fuel used when storing or transporting black pellet solid fuel, comprising: a mixing step of mixing the black pellet solid fuel with coal, the moisture content of which has been adjusted to 6% by mass or more by adding water, so that a mixing ratio of the black pellet solid fuel to the coal (the black pellet solid fuel / the coal) is 0.1 or more and 9.0 or less by mass; The coal with the adjusted moisture content is obtained by soaking the coal in water, spraying water onto the coal, or storing the coal in a humidified space. How to mix black pellet solid fuel.

2. The mixing step is a step of adding the coal to the black pellet solid fuel. A method for mixing the black pellet solid fuel according to claim 1.

3. The black pellet solid fuel is at least one of black pellet solid fuel stored in a storage container or a storage site and black pellet solid fuel transported by a transport means. A method for mixing the black pellet solid fuel according to claim 1 or 2.

4. The mixing step is carried out at least at any stage before storing the black pellet solid fuel in the storage container or the storage site and before transporting the black pellet solid fuel by the transport means. A method for mixing the black pellet solid fuel according to claim 3.

5. The mixing step is carried out at least at any stage after the black pellet solid fuel is stored in the storage container or storage area, or during the transportation by the transportation means. A method for mixing the black pellet solid fuel according to claim 3 or 4.

6. The transport means is at least one of an unloader, an elevator, a car, a conveyor, a belt feeder, and a ship. A method for mixing the black pellet solid fuel according to any one of claims 3 to 5.

7. In the mixing step, the black pellet solid fuel and the coal are mixed by alternately stacking the black pellet solid fuel and the coal. A method for mixing the black pellet solid fuel according to any one of claims 1 to 6.

8. The coal is bituminous coal, subbituminous coal, or lignite; A method for mixing the black pellet solid fuel according to any one of claims 1 to 7.

9. In the mixing step, the coal is adjusted to a moisture content of 10% by mass or more by adding water. A method for mixing the black pellet solid fuel according to any one of claims 1 to 8.

10. A mixture of the black pellet solid fuel and the coal obtained by carrying out the black pellet solid fuel mixing method according to any one of claims 1 to 9. Black pellet fuel mix.

11. a mixing step of mixing black pellet solid fuel with coal whose moisture content has been adjusted to 6% by mass or more by adding water, so that a mixing ratio of the black pellet solid fuel to the coal (the black pellet solid fuel / the coal) is 0.1 or more and 9.0 or less by mass; a transporting step of leaving the mixture of the black pellet solid fuel and the coal obtained in the mixing step to stand for one hour or more, and then transporting the mixture from the place where the mixing step was carried out to another place, The coal with the adjusted moisture content is obtained by soaking the coal in water, spraying water onto the coal, or storing the coal in a humidified space. How to transport black pellet solid fuel.

12. In the mixing step, the coal is adjusted to a moisture content of 10% by mass or more by adding water. The method for transporting black pellet solid fuel according to claim 11.

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