JP6199020B2 - Production method of ashless coal - Google Patents

Description

  The present invention relates to a method for producing ashless coal for obtaining ashless coal from which ash is removed from coal.

  As a method for producing ashless coal, for example, there is one described in Patent Document 1. The method for producing ashless coal described in Patent Document 1 is prepared by mixing coal and a solvent to prepare a slurry, heating the resulting slurry to extract a coal component soluble in the solvent, and extracting the coal component. The slurry is separated into a solution part containing a coal component soluble in the solvent and a non-solution part containing a coal component insoluble in the solvent, and then the solvent is separated from the separated solution part to remove ashless coal. It is to get. The method for producing ashless coal described in Patent Document 1 uses, as a raw material for ashless coal, coal obtained by mixing caking coal with general coal when adopting the gravity sedimentation method for separating the solution portion and the non-solution portion. It is characterized by that.

  According to the production method described in Patent Document 1, the sedimentation rate of the solvent-insoluble component is improved when the gravity sedimentation method is performed, and as a result, ashless coal from which ash is sufficiently removed is produced with high efficiency and at low cost. be able to.

JP 2009-227718 A

  As described above, in Patent Document 1, the sedimentation rate of the solvent-insoluble component is improved by using coal obtained by mixing caking coal with general coal as a raw material. However, for example, when producing ashless coal in the coal production area, there is no room for selecting various types of raw material (coal). That is, when manufacturing ashless coal, as described in Patent Document 1, it may be difficult to mix caking coal with steam coal.

  The present invention has been made in view of the above circumstances, and the purpose thereof is, for example, a case where ashless coal is produced in a coal production area where there is no room for selecting various types of raw material (coal). Another object of the present invention is to provide a method for producing ashless coal, which can produce ashless coal from which ash is sufficiently removed at high efficiency and at low cost.

The present invention includes an extraction step for extracting a coal component soluble in a solvent by heating a slurry obtained by mixing coal and a solvent, and a slurry obtained in the extraction step with a coal component soluble in a solvent. A separation step of separating the solution into a solid content concentrate in which a coal component insoluble in the solvent is concentrated, and obtaining ashless coal by evaporating and separating the solvent from the solution separated in the separation step A process for producing ashless coal. Method of manufacturing ashless coal prior to mixing the coal and solvent, further comprising a source separation step of separating the coal more granularity predetermined threshold, separated by the material separation process, the predetermined threshold value By performing the said extraction process using the coal of the above particle size, the cohesiveness of the coal component insoluble in a solvent is improved.

When the extraction step is performed using coal having a particle size equal to or larger than a predetermined threshold, the cohesiveness of coal components insoluble in the solvent is improved. Thereby, the separation efficiency of the coal component insoluble in the solvent in the separation step is improved. As a result, ashless coal from which ash is sufficiently removed can be produced with high efficiency and at low cost.
Here, in this manufacturing method, the use of the caking coal described in Patent Document 1 is unnecessary. That is, according to the present invention, for example, even when ashless coal is produced in a coal production area where there is no room for selecting various types of raw material (coal), nothing like caking coal is used. In addition, ashless coal from which ash is sufficiently removed can be produced at high efficiency and at low cost. Note that the caking coal described in Patent Document 1 is more expensive than steam coal. In the present invention, it is not necessary to use such expensive caking coal. That is, also from this viewpoint, according to the present invention, ashless coal from which ash is sufficiently removed can be produced at low cost.
Moreover, by performing the said extraction process using the coal of the particle size more than a predetermined | prescribed threshold value, in addition to the cohesiveness of the coal component insoluble in a solvent improving, the extraction rate of the coal component soluble in a solvent increases. . According to the present invention, ashless coal can be produced with high efficiency from the viewpoint of increasing the extraction rate of coal components soluble in a solvent.

It is a block diagram which shows the ashless coal manufacturing equipment for demonstrating the manufacturing method of the ashless coal which concerns on one Embodiment of this invention. It is a figure for demonstrating the outline | summary of the verification experiment that the sedimentation (separation property, sedimentation speed) of the coal component insoluble in a solvent improves with the manufacturing method which concerns on this invention. It is a graph which shows the particle size distribution of coal. It is a graph which shows the result of a sedimentation verification experiment.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the ashless coal production facility 100 includes a coal hopper 1, a solvent tank 2, a slurry preparation tank 3, a transfer pump 4, a preheater 5, in order from the upstream side of the ashless coal (HPC) production process. An extraction tank 6, a gravity settling tank 7, a filter unit 8, and solvent separators 9 and 10 are provided.

  Here, the method for producing ashless coal of the present embodiment includes a raw material analysis stage, a pulverization process, a raw material separation process, an extraction process, a separation process (solvent-soluble component separation process), an ashless coal acquisition process, and a by-product coal. It has an acquisition process. Hereinafter, the raw material analysis stage and each process will be described. In addition, there is no restriction | limiting in particular in the coal used as a raw material in this manufacturing method, Bituminous coal with a high extraction rate (ratio of the soluble component of the coal extracted to a solvent) may be used, and cheaper inferior quality coal (sublimation). (Bituminous coal, brown coal) may be used. The ashless coal means ash content of 5% by weight or less, preferably 3% by weight or less.

(Raw material analysis stage)
The raw material analysis stage is a stage in which sedimentation analysis of coal components insoluble in solvents (solvent insoluble components in coal, for example, ash content of coal) is performed for each coal particle size. In addition, sedimentation analysis is performed after pulverizing coal as needed.

  Specifically, the raw material analysis stage is a stage in which basic data on the relationship between the sedimentation property of the coal component insoluble in the solvent and the coal particle size is obtained in advance for the raw material (coal). The data shown in FIG. 4 shown later is an example of basic data. Based on the basic data (analysis result data) acquired in the raw material analysis stage, the particle size (size range) of coal with good sedimentation of coal components insoluble in the solvent, separated in the subsequent raw material separation step and used in the extraction step decide.

Here, although the result verified by experiment is mentioned later, as a result of earnestly examining the sedimentation property of the coal component insoluble in the solvent, the present inventors found that the sedimentation property of the coal component insoluble in the solvent It was found that the fine particle size tends to be good, but the sedimentation property is worsened when the particle size is extremely fine.
Generally, the fineness (smallness) of the particle size becomes higher as the particle cohesiveness. When the cohesion is high, the sedimentation property of the particles in the liquid is improved, that is, the sedimentation rate is increased. This is because the particles strongly aggregate to form a lump and the diameter increases. On the other hand, regarding coal, if the particle size is extremely fine, aggregation of coal components insoluble in the solvent does not proceed sufficiently (low aggregation), and sedimentation may be worsened.

That is, in the sedimentation analysis described above performed in the raw material analysis stage, a predetermined threshold value (particle size threshold value) at which the sedimentation property deteriorates is examined, and coal having a particle size less than this threshold value is insoluble in a solvent than 100% by weight coal. This is for determining a coal particle size range (for example, coal having a particle size equal to or larger than a predetermined threshold) with good sedimentation properties of coal components.

  In addition, although an extraction process, a separation process (solvent soluble component separation process), and an ashless coal acquisition process are a series of continuous processes performed each time, this raw material analysis stage is a series of continuous processes performed every time. There is no need to be done as. For example, the raw material analysis step may be performed at least once when the same raw material (coal) is continuously used in the production of ashless coal.

  In addition, in the sedimentation analysis in the raw material analysis stage, a solvent used in an extraction process described later is used, and conditions are set so that the heating temperature and pressure are equivalent to those in the extraction process (extraction main process).

  In the raw material analysis stage, the coal particle size may be set as appropriate according to the particle size distribution of the entire raw material coal, etc., and the analysis may be repeated a plurality of times by changing the particle size range.

(Crushing process)
Before performing the raw material separation step described later, coal (raw material) is pulverized (pulverization step). From the coal pulverized in this pulverization step, coal having a particle size equal to or larger than a predetermined threshold is separated in the next raw material separation step. In the pulverization step, when coal is slurried in a slurry preparation step described later, the coal is pulverized to such an extent that its handling properties (liquidity from the pump, reduction of clogging frequency) are improved. That is, by carrying out the pulverization step, the handling property when coal is slurried is improved. Specifically, the coal is pulverized by a pulverizer (not shown) so that the maximum particle size is, for example, about 1 mm to 5 mm. Note that even if coal is pulverized so that the maximum particle diameter is about 1 mm to 5 mm, coal having a particle diameter of about 1 mm to 5 mm or less is not 100% by weight. Of course, there are many coals having a particle size of less than 1 mm. This pulverization step is not an essential step. For example, even if the collected coal (raw material) is used as it is, if the coal is slurried in a slurry preparation step described later, the pulverization step may be omitted as long as there is no problem in handling properties.

(Raw material separation process)
Before performing a slurry preparation step, which will be described later, which mixes coal as a raw material and a solvent, first, coal having a particle size equal to or larger than a predetermined threshold is separated (raw material separation step). Specifically, for example, coal is separated so that coal having a particle size of a predetermined threshold value or more becomes 95% by weight or more. “Coal having a particle size equal to or greater than a predetermined threshold” refers to coal having a particle size range determined based on the basic data (analysis result data) obtained in the raw material analysis stage. Further, from the viewpoint of improving the extraction rate, those having a fine particle size show a tendency for the extraction rate to decrease, so that an effect of improving the yield can also be obtained by separation.

Here, the “ predetermined threshold value” (the lower limit value of the particle size of the raw coal) is, for example, 0.075 mm or 0.15 mm. From the viewpoint of improving the extraction rate of coal components soluble in the solvent in the extraction step described later, the threshold is preferably set to 0.075 mm. On the other hand, the upper limit of the particle size of the raw coal is, for example, 0.15 mm or 0.25 mm when the lower limit is 0.075 mm. When the lower limit is set to 0.15 mm, the upper limit is set to 0.25 mm, for example. Note that in the case of the any value the lower limit is also a predetermined threshold value or more, and coal predetermined upper limit value or less granularity it is preferred to separate the coal so that 90 wt% or more. The predetermined upper limit value is, for example, 0.5 mm, and can be about 5.0 mm.

  When verifying the particle size of coal, such as whether the particle size of coal is 0.075 mm or more, or 0.15 mm or less, for example, a screening test defined in JIS A 1102 is used.

For example, a sieve (not shown) is used for separating coal. For example, the sieve is installed on the upstream side of the coal hopper 1, and for example, coal having a particle size less than a predetermined threshold (coal having a particle size not used for producing ashless coal) is removed by sieving. And the coal of the particle size more than a predetermined threshold used for manufacture of ashless coal is thrown into the coal hopper 1. In addition, since it is sufficient that the necessary coal can be separated before mixing the coal and the solvent, the installation position of the sieve is not limited to the upstream side of the coal hopper 1.

Examples of separation means (separation method) other than sieving include a screen. As a separation method other than these, a sedimentation separation method used as a coal preparation method may be used. This sedimentation separation method can be used because the range of the particle diameter can be limited by the sedimentation range (a small range of particles and a large range of particles can be removed simultaneously). Furthermore, a separation method using centrifugal force such as a cyclone can be used.
The coal predetermined threshold or more particle size, to also be a coal all over granularity predetermined threshold, even the upper limit value as well as a predetermined threshold value or more specific range of particle size (a predetermined threshold (lower limit) It may be coal of a certain particle size range).

(Extraction process)
An extraction process is a process of extracting the coal component soluble in a solvent by heating the slurry obtained by mixing coal and a solvent. Using coal having a particle size equal to or greater than a predetermined threshold separated in the raw material separation step (specifically, for example, using coal containing 95% by weight or more of coal having a particle size equal to or greater than a predetermined threshold) ) Perform this extraction step. The extraction process consists of a slurry preparation process in which coal and a solvent are mixed to prepare a slurry, and an extraction main process (solvent soluble) in which the slurry obtained in the slurry preparation process is heated to extract a coal component soluble in the solvent. Component extraction step).

<Slurry preparation process>
The slurry preparation step is a step of preparing a slurry by mixing coal and a solvent. This slurry preparation process is implemented in the slurry preparation tank 3 in FIG. Coal as a raw material is charged into the slurry preparation tank 3 from the coal hopper 1, and a solvent is charged into the slurry preparation tank 3 from the solvent tank 2. The coal and solvent charged into the slurry preparation tank 3 are mixed by the stirrer 3a to become a slurry composed of coal and solvent.

  The mixing ratio of coal with respect to the solvent is, for example, 10 to 50% by weight on the basis of dry coal, and more preferably 20 to 35% by weight.

<Extraction main process>
This extraction step is a step of heating the slurry obtained in the slurry preparation step to extract a coal component soluble in the solvent (dissolve in the solvent). This extraction main process is implemented in the preheater 5 and the extraction tank 6 in FIG. The slurry prepared in the slurry preparation tank 3 is supplied to the preheater 5 by the transfer pump 4 and heated to a predetermined temperature, then supplied to the extraction tank 6, and held at the predetermined temperature while being stirred by the stirrer 6a. Extraction is performed.

  Coal in the slurry is agglomerated by colliding with each other in the extraction tank 6. Since the number of solids in the extraction tank 6 increases as the particle size of the coal decreases, the chance of collision in the extraction main process increases. That is, the smaller the coal particle size, the higher the cohesion. However, as described above, if the particle size of the coal is extremely fine, aggregation of the coal component insoluble in the solvent does not proceed sufficiently (low aggregation property), and the sedimentation property may worsen on the contrary. .

  When extracting coal components that are soluble in the solvent by heating the slurry obtained by mixing coal and solvent, a solvent with a large dissolving power for coal, often an aromatic solvent (hydrogen donating property) Or a non-hydrogen-donating solvent) and coal are mixed and heated to extract organic components in the coal.

  The non-hydrogen donating solvent is a coal derivative which is a solvent mainly composed of a bicyclic aromatic and purified mainly from a coal carbonization product. This non-hydrogen donating solvent is stable even in a heated state and has an excellent affinity for coal. Therefore, when this non-hydrogen donating solvent is used, the extraction rate is increased. The non-hydrogen donating solvent is a solvent that can be easily recovered by a method such as distillation. Main components of the non-hydrogen donating solvent include bicyclic aromatic naphthalene, methyl naphthalene, dimethyl naphthalene, trimethyl naphthalene and the like, and other non-hydrogen donating solvent components have aliphatic side chains. Naphthalenes, anthracenes, fluorenes, and these include biphenyl and alkylbenzenes having long aliphatic side chains.

  In the above description, the case where a non-hydrogen-donating compound is used as a solvent has been described, but it is needless to say that a hydrogen-donating compound (including coal liquefied oil) typified by tetralin may be used as a solvent. . When a hydrogen donating solvent is used, the yield of ashless coal is improved.

  Further, the boiling point of the solvent is not particularly limited. From the viewpoint of pressure reduction in the extraction main step and separation step, extraction rate in the extraction main step, solvent recovery rate in the ashless coal acquisition step, etc., for example, a boiling point of 180 to 300 ° C., particularly 240 to 280 ° C. A solvent is preferably used.

  The heating temperature of the slurry in this extraction step is not particularly limited as long as the solvent-soluble component can be dissolved, and is, for example, 300 to 420 ° C. from the viewpoint of sufficient dissolution of the solvent-soluble component and improvement of the extraction rate. More preferably, it is 360-400 degreeC.

  Also, the heating time (extraction time) is not particularly limited, but is, for example, 10 to 60 minutes from the viewpoint of sufficient dissolution and improvement of the extraction rate. The heating time is the total heating time in the preheater 5 and the extraction tank 6 in FIG.

  This extraction step is performed in the presence of an inert gas such as nitrogen. The pressure in the extraction tank 6 is preferably 1.0 to 2.0 MPa, although it depends on the temperature at the time of extraction and the vapor pressure of the solvent used. When the pressure in the extraction tank 6 is lower than the vapor pressure of the solvent, the solvent volatilizes and is not confined in the liquid phase, so that extraction cannot be performed. In order to confine the solvent in the liquid phase, a pressure higher than the vapor pressure of the solvent is required. On the other hand, if the pressure is too high, the cost of the equipment and the operating cost increase, which is not economical.

  As in this embodiment, after mixing coal and solvent, the obtained slurry is not heated to extract coal components soluble in the solvent, but only the solvent is heated first and heated. Alternatively, coal may be supplied into a solvent at a high temperature (for example, 380 ° C.) (supplied in a dry state), the coal may be mixed and heated, and solvent-soluble components in the coal may be extracted with the solvent.

(Separation process)
In the separation step (solvent soluble component separation step), the slurry obtained in the extraction step is subjected to, for example, gravity precipitation, a solution containing a coal component soluble in the solvent, and a solid content in which the coal component insoluble in the solvent is concentrated. This is a step of separating into a concentrated liquid (solvent insoluble component concentrated liquid). This separation step is performed in the gravity settling tank 7 in FIG. The slurry obtained in the extraction step is separated into a supernatant liquid as a solution and a solid content concentrated liquid by gravity in the gravity settling tank 7. The supernatant liquid in the upper part of the gravity sedimentation tank 7 is sent to the solvent separator 9 through the filter unit 8 as necessary. The solid concentration liquid settled in the lower part of the gravity settling tank 7 is sent to the solvent separator 10.

  The gravitational sedimentation method is a method in which a slurry is retained in a tank to settle and separate solvent-insoluble components using gravity. A solvent-insoluble component (for example, ash) having a specific gravity greater than that of a solution containing a coal component that is soluble in the solvent is settled by gravity in the lower part of the gravity settling tank 7. A continuous separation process is possible by continuously discharging the supernatant from the top and the solid concentrate from the bottom while continuously supplying the slurry into the tank.

  Further, since the slurry is allowed to stand in the gravity settling tank 7, the aggregation state of the solvent-insoluble component is easily maintained as it is after the extraction main process. This is because in the stationary state, almost no force is applied to solve the aggregation state. Thus, according to the gravity sedimentation method, the separation efficiency of the coal component insoluble in the solvent (also the separation efficiency of the coal component soluble in the solvent) is further improved. In addition, leaving still means that it does not perform anything such as agitation and is left as it is.

  The gravity sedimentation tank 7 is preferably kept warm (or heated) or pressurized in order to prevent reprecipitation of solvent-soluble components eluted from coal. The heat retention (heating) temperature is, for example, 300 to 380 ° C., and the tank internal pressure is, for example, 1.0 to 3.0 MPa.

  As a method of separating the slurry obtained in the extraction step into a solution containing a coal component soluble in a solvent and a solid concentrate concentrated with a coal component insoluble in the solvent, filtration is performed in addition to the gravity sedimentation method. Method and centrifugation.

(Ashless coal acquisition process)
The ashless coal acquisition step is a step of obtaining ashless coal (HPC) by evaporating and separating the solvent from the solution (supernatant liquid) separated in the separation step. This ashless charcoal acquisition process is performed by the solvent separator 9 in FIG. The solution separated in the gravity settling tank 7 is filtered by the filter unit 8 and then supplied to the solvent separator 9, and the solvent is evaporated and separated from the supernatant in the solvent separator 9.

  As a method for separating the solvent from the solution (supernatant liquid), a general distillation method, evaporation method or the like can be used. The solvent separated by the solvent separator 9 can be returned to the solvent tank 2 and circulated for repeated use. By separating the solvent from the supernatant, ashless charcoal (HPC) substantially free of ash can be obtained.

<Uses of ashless coal (HPC)>
Ashless coal (HPC) contains almost no ash, has no moisture, and exhibits a higher calorific value than raw coal. Further, the softening and melting property, which is a particularly important quality as a raw material for iron-making coke, is greatly improved, and the obtained ashless coal has a good softening and melting property even if the raw material coal does not have the softening and melting property. Therefore, ashless coal can be used, for example, as a blended coal for coke raw materials. In addition, ashless coal containing almost no ash content has high combustion efficiency and can reduce the generation of coal ash. Therefore, the use of ashless coal as a gas turbine direct injection fuel in a high-efficiency combined power generation system based on gas turbine combustion has attracted attention.

  Furthermore, ashless charcoal can be used as an electrode material for, for example, an electric furnace for steel making and a capacitor. When producing ashless coal as an application for electrode materials or the like, the production amount of ashless coal may be smaller than when producing as an application for coke raw materials (while the unit price of ashless coal is higher). When the production amount of ashless coal is small, the production facility may be small. If the production equipment is small (the raw material is small) and the unit price of the product ashless coal is high, the cost of finely pulverizing the raw material (coal) does not significantly affect the total cost of the product (ashless coal) production .

(By-product coal acquisition process)
The byproduct charcoal acquisition step is a step of obtaining byproduct charcoal by evaporating and separating the solvent from the solid concentrate separated in the separation step. This byproduct charcoal acquisition step is performed by the solvent separator 10 in FIG. The solid content concentrate separated in the gravity sedimentation tank 7 is supplied to the solvent separator 10, and the solvent is evaporated and separated from the solid content concentrate in the solvent separator 10. In addition, a byproduct charcoal acquisition process is not an essential process.

  As a method for separating the solvent from the solid concentrate, a general distillation method, evaporation method, or the like can be used as in the above-described ashless coal acquisition step. The solvent separated by the solvent separator 10 is returned to the solvent tank 2 and can be circulated and used repeatedly. By separating the solvent, by-product charcoal (also referred to as RC or residual charcoal) in which solvent-insoluble components including ash and the like are concentrated can be obtained from the solid concentrate.

<Uses of by-product coal (RC)>
By-product charcoal contains ash, but has no water and has a sufficient calorific value. By-product coal does not exhibit softening and melting properties, but the oxygen-containing functional groups are eliminated, so that when used as a blended coal, it inhibits the softening and melting properties of other coals contained in this blended coal. It is not a thing. Therefore, this by-product coal can be used as a part of the blended coal of the coke raw material, as in the case of ordinary non-slightly caking coal, and is used for various fuels without using the coke raw coal. It is also possible.

(Verification experiment)
It verified that the sedimentation property (separability, sedimentation speed) of the coal component (for example, ash content) insoluble in a solvent improved by the manufacturing method which concerns on this invention. This will be described with reference to FIGS.

  Coal having a particle size of several centimeters to several tens of centimeters was pulverized to obtain coal having a particle size of 1.0 mm or less (maximum particle size of 1.0 mm or less). The particle size distribution of this coal is shown in FIG. In FIG. 3, coal pulverized so as to have a particle size of 1.0 mm or less was classified using sieves having openings of 0.045, 0.075, 0.15, 0.25, and 0.50 mm. The results are graphed. The particle size (particle size) distribution was examined by a sieving operation shown in JIS A1102.

Among the above coal pulverized so that the particle size is 1.0 mm or less, three types of coal with particle size ranges of <0.075 mm, 0.075-0.150 mm, 0.150-0.250 mm are used. Used in experiments.
In addition, <0.075 mm coal is coal that passed through a 0.075 mm sieve (coal having a particle size of less than 0.075 mm), and 0.075-0.150 mm coal is 0.150 mm Coal that passed through the sieve but not passed through the sieve of 0.075 mm (coal having a particle size of 0.075 mm or more and less than 0.150 mm), 0.150-0.250 mm coal is 0.250 mm Coal that passed through the sieve but did not pass through the sieve of 0.150 mm (coal having a particle size of 0.150 mm or more and less than 0.250 mm).

  Each of these three types of coal was mixed with a solvent to prepare a slurry having a coal concentration of 20 wt% dry (based on dry coal). As a solvent, an oil component (coal derivative) purified from coal containing methylnaphthalene, which is a bicyclic aromatic compound, as a main component was used.

  The vertically long autoclave 50 used in the experiment was a cylindrical pressure vessel, and as shown in FIG. 2, the liquid was allowed to escape from a total of two places at a predetermined height from the bottom. Further, a stirrer 50 a is installed inside the autoclave 50. The autoclave 50 is erected so that the longitudinal direction thereof coincides with the vertical direction.

  The prepared slurry was put into the autoclave 50. And extraction of a solvent soluble component was performed for 20 minutes at 400 degreeC. Thereafter, the temperature was lowered to 380 ° C. and stirring was performed, and the liquid level was adjusted by extracting the liquid from the sampling position P1 to the sampling container 51a. Liquid level adjustment means that the liquid level in the autoclave 50 at this time is adjusted so that the liquid level comes to the level (height) of the sampling position P1, as shown in FIG. is there. Moreover, the density | concentration C0 (initial density | concentration) of the solvent insoluble component contained in the liquid at this time was measured.

  Then, stirring was stopped and the liquid was allowed to stand for a predetermined time t. After time t, a liquid was collected from the sampling position P2 into the sampling container 51b, and the concentration Ct of the solvent-insoluble component contained in the liquid was measured.

  Then, the sedimentation rate [%] of the solvent-insoluble component was calculated from the initial concentration C0 and the concentration Ct after the standing time t. The results are shown in FIG.

  From the result of 0.075-0.150 mm coal (shown by the alternate long and short dash line) and the result of 0.150-0.250 mm coal (shown by the solid line), the particle size (range) of the raw coal is fine. It can be seen that the sedimentation property (separability, sedimentation rate) of the solvent-insoluble component is improved.

  On the other hand, to compare the results with 0.075-0.150 mm and 0.150-0.250 mm coal with the results with <0.075 mm coal (shown in dotted lines), <0.075 mm Coal is slower in reducing the concentration of solvent-insoluble components. From this result, it is understood that when the particle size (range) of the raw material coal is extremely fine, the sedimentation property of the solvent-insoluble component deteriorates on the contrary. The finer the particle size (range) of coal, the faster the sedimentation rate of solvent-insoluble components will not necessarily be.

From these, it is understood that the sedimentation property of the solvent-insoluble component can be maximized by using coal having a particle size equal to or larger than a predetermined threshold. This “ predetermined threshold value” is, for example, 0.075 mm or 0.15 mm based on experimental results.

  In addition, in order to compare the result with 0.075-0.150 mm coal and the result with 0.150-0.250 mm coal, it is better to use 0.075-0.150 mm coal in a solvent-insoluble state. The sedimentation rate of the components does not decline over time.

(Action / Effect)
In the present invention, the extraction step is performed using coal having a particle size equal to or greater than the “ predetermined threshold value” to improve the cohesiveness of the coal component insoluble in the solvent. By improving the cohesiveness of the coal component insoluble in the solvent, the separation efficiency of the coal component in the separation step (solvent soluble component separation step) (the sedimentation speed when using the gravity sedimentation method) is improved. As a result, ashless coal from which ash is sufficiently removed can be produced with high efficiency and at low cost. In this manufacturing method, the use of the caking coal described in Patent Document 1 is unnecessary. That is, according to the present invention, for example, even when ashless coal is produced in a coal production area where there is no room for selecting various types of raw material (coal), nothing like caking coal is used. In addition, ashless coal from which ash is sufficiently removed can be produced at high efficiency and at low cost. Moreover, by performing an extraction process using the coal of the particle size more than a predetermined | prescribed threshold value, in addition to the aggregability of the coal component insoluble in a solvent improving, the extraction rate of the coal component soluble in a solvent increases. According to the present invention, ashless coal can be produced with high efficiency from the viewpoint of increasing the extraction rate of coal components soluble in a solvent.

  Moreover, the load in a separation process (solvent soluble component separation process) can be reduced compared with the case where an extraction process is performed using all the raw material coal without going through a raw material separation process. When, for example, a gravity sedimentation tank is used in the separation step, the capacity and the like can be reduced. Alternatively, the throughput can be increased in a gravity sedimentation tank of the same scale.

If the “ predetermined threshold value (lower limit)” is, for example, 0.075 mm in particle size, as can be seen from FIG. 4, the separation efficiency of coal components insoluble in the solvent is further increased. Moreover, when the particle size of coal (raw material) is extremely fine, the extraction rate of coal components soluble in the solvent tends to decrease. Therefore, by setting the “ predetermined threshold” to, for example, 0.075 mm in particle size, there is an effect that the extraction rate of coal components soluble in the solvent is increased.

Here, it is preferable that the coal used in the extraction step includes 90% by weight or more of coal having a particle size not less than a “ predetermined threshold value” and not more than a predetermined upper limit (for example, 5 mm). Using coal separated in the raw material separation step and containing 90% by weight or more of coal having a particle size not less than a “ predetermined threshold value” and not more than a predetermined upper limit (for example, 5 mm, particularly preferably 0.5 mm) By performing the extraction step, the separation efficiency due to the improved cohesiveness is further increased.

  In addition, it further has a raw material analysis stage that performs sedimentation analysis of coal components insoluble in the solvent according to the coal particle size, and based on the analysis result of this raw material analysis stage, the separation of the coal used in the extraction process is separated. It is also preferred to determine the particle size. This is because the separation efficiency of the coal component insoluble in the solvent can be reliably improved by performing the sedimentation analysis.

  In addition, in the separation step of separating the solution containing coal components soluble in the solvent and the solid content concentrate in which the coal components insoluble in the solvent are concentrated, separation methods such as gravity sedimentation, filtration, and centrifugation are used. Can be used. Of these separation methods, the gravity sedimentation method can suppress the equipment cost and operation cost necessary for carrying out the method lower than the filtration method and the centrifugal separation method. That is, if the gravity sedimentation method is used in the separation step, ashless coal can be produced at a lower cost. Moreover, according to the gravity sedimentation method, the aggregation state of the solvent-insoluble component is easily maintained, so that the separation efficiency in the separation step is further improved.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. .

1: Coal hopper 2: Solvent tank 3: Slurry preparation tank 4: Transfer pump 5: Preheater 6: Extraction tank 7: Gravity settling tank 8: Filter unit 9, 10: Solvent separator 100: Ashless coal production equipment

Claims (5)

An extraction step of heating a slurry obtained by mixing coal and a solvent to extract a coal component soluble in the solvent;
A separation step of separating the slurry obtained in the extraction step into a solution containing a coal component soluble in a solvent and a solid content concentrate in which a coal component insoluble in the solvent is concentrated;
Ashless coal acquisition step of obtaining ashless coal by evaporating and separating the solvent from the solution separated in the separation step;
In a method for producing ashless coal,
Before mixing the coal and the solvent, further comprising a raw material separation step of separating coal having a particle size of a predetermined threshold value or more,
Ashless coal, which improves the cohesiveness of coal components insoluble in a solvent by performing the extraction step using coal having a particle size equal to or greater than the predetermined threshold, separated in the raw material separation step Manufacturing method. In the manufacturing method of ashless coal of Claim 1,
The method for producing ashless coal, wherein the extraction step is performed using coal separated so that coal having a particle size of the predetermined threshold value or more becomes 95% by weight or more. In the manufacturing method of the ashless coal of Claim 1 or 2,
Wherein the material separation process, said not less than a predetermined threshold value, the coal of the predetermined threshold value or greater than a predetermined upper limit value or less of the particle size are separated coal so that 90 wt% or more,
The extraction step is performed using coal separated in the raw material separation step and containing 90% by weight or more of coal having a particle size not less than the predetermined threshold and not more than the predetermined upper limit. A method for producing ashless coal. In the manufacturing method of the ashless coal in any one of Claims 1-3,
It has a raw material analysis stage that performs sedimentation analysis of coal components insoluble in solvents according to coal particle size,
A method for producing ashless coal, characterized in that, based on the analysis result of the raw material analysis stage, the particle size of coal used in the extraction step after being separated in the raw material separation step is determined. In the manufacturing method of the ashless coal in any one of Claims 1-4,
Before the raw material separation step, has a pulverization step of pulverizing coal,
In the raw material separation step, coal having a particle size equal to or larger than the predetermined threshold is separated from the coal pulverized in the pulverization step.

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