JP5839567B2 - Solvent separation method - Google Patents

Description

  The present invention relates to a method for separating solvent-containing water produced in a process for producing ashless coal from which ash is removed from coal into solvent and water.

  As a manufacturing method of ashless coal, there exists a thing described in patent documents 1, for example. In Patent Literature 1, a slurry is prepared by mixing coal and a solvent, and the resulting slurry is heated to extract a coal component soluble in the solvent, and soluble in the solvent from the slurry from which the coal component is extracted. A method for producing ashless coal is described in which a solution containing various coal components is separated, and then a solvent is recovered from the separated solution to obtain ashless coal. As the solvent, oil derived from coal is used.

Japanese Patent Laid-Open No. 2005-120185

Here, in the process for producing ashless coal as described above, water (H ₂ O) is generated from the raw coal. In the extraction of the coal component, the slurry is heated to a temperature of, for example, 300 to 420 ° C. Under such a high temperature, coal undergoes a thermal decomposition reaction, and methane (CH ₄ ), carbon dioxide (CO ₂ ), water (H ₂ O), and the like are generated. In addition, the raw material coal originally contains moisture, and moisture is separated from the coal when the coal component is extracted by the solvent.

Water generated from coal by thermal decomposition (H 2 _O), and moisture separated from the coal upon extraction of coal components (H 2 _O), so is discharged as a gas (steam) to the outside of the ash-free coal production facility There is a lot of solvent in the gas (solvent-containing water). For this reason, if all of the gas is discarded, the loss of the solvent becomes very large, and it becomes necessary to replenish a lot of solvent. As a result, the running cost increases.

  Further, in order to discard the gas containing the solvent, for example, it is necessary to remove the solvent from the gas by using an adsorbent. When the amount of the solvent contained in the gas is large, the treatment cost becomes very high. End up. Further, it is not easy to separate the solvent adsorbed on the adsorbent from the adsorbent, that is, it is difficult to reuse the adsorbent that has been subjected to the adsorption treatment.

  The present invention has been made in view of the above circumstances, and its object is to easily separate solvent-containing water generated in the process of producing ashless coal into solvent and water without using an adsorbent or the like. It is to provide a way that can be done.

  The present invention includes an extraction step of extracting a coal component soluble in a solvent by heating a slurry obtained by mixing coal and a solvent, and a coal component soluble in a solvent from the slurry obtained in the extraction step. A separation step of separating the solution containing, and an ashless coal acquisition step of obtaining ashless coal by evaporating and separating the solvent from the solution separated in the separation step, and containing a solvent produced in the process of producing ashless coal This is a solvent separation method for separating water into a solvent and water. The solvent separation method includes a solvent-containing water supply step of supplying the solvent-containing water to a solvent separation pressure vessel, and a temperature at which the temperature of the solvent-containing water supplied to the solvent separation pressure vessel is maintained at a predetermined temperature. And holding the solvent-containing water by lowering the liquid water and raising the solvent in the solvent separation pressure vessel due to the difference between the density of the water at the predetermined temperature and the density of the solvent. Is separated into a solvent and water.

  “Solvent-containing water” refers to water in a state where a solvent and water are mixed (mixed state) regardless of whether it is in a liquid state or a gas state. Also, “occurs in the process of producing ashless coal” means that it occurs as a by-product in any part of the ashless coal production process.

  According to the present invention, solvent-containing water generated in the process of producing ashless coal can be easily separated into a solvent and water without using an adsorbent or the like. As a result, the adsorbent can be reused, the solvent loss can be suppressed, and the water disposal cost can be reduced.

It is a block diagram which shows the ashless coal manufacturing equipment provided with the pressure vessel for solvent separation for isolate | separating solvent containing water into a solvent and water. It is a figure for demonstrating the outline | summary of the separation test which isolate | separates solvent containing water into a solvent and water. It is a graph which shows the result of a separation test.

  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 sedimentation tank 7, a filter unit 8, and a solvent separator 9 are provided. The solvent separator 9 is for evaporating and separating the solvent from the solution (supernatant liquid) separated in the gravity settling tank 7.

  Further, on the downstream side of the weight sedimentation tank 7, the solvent is separated from the solvent-insoluble component concentrate (solid content concentrate) separated in the weight sedimentation tank 7 (the solvent is separated from the solid content concentrate). A solvent separator 10 (for recovery) is arranged.

  The ashless coal production facility 100 includes a solvent separation pressure vessel 11 for separating the solvent-containing water into a solvent and water. The solvent separation pressure vessel 11 is connected to the extraction tank 6 by a pipe 25. That is, in this embodiment, gaseous solvent-containing water generated in the extraction step in the process of producing ashless coal is supplied from the extraction tank 6 to the pressure vessel 11 for solvent separation into liquid solvent and liquid water. It is separated.

  The solvent separation pressure vessel 11 may be connected to the gravity settling tank 7 instead of the extraction tank 6 by a pipe or the like. That is, gaseous solvent-containing water (solvent is liquid and solvent is mixed in water vapor) generated in the extraction process is supplied from the gravity settling tank 7 to the solvent separation pressure vessel 11 and separated into solvent and water. May be. Further, by connecting the solvent separation pressure vessel 11 to the gravity settling tank 7, when a small amount of water is generated in the gravity settling tank 7, the solvent-containing water generated here is used as a solvent in the solvent separation pressure vessel 11. It can be separated into water.

  Further, one solvent separation pressure vessel 11 may be connected to both the extraction tank 6 and the gravity settling tank 7, and one solvent separation pressure is provided for each of the extraction tank 6 and the gravity settling tank 7. The container 11 may be connected. When moisture remains in the slurry supplied to the gravity settling tank 7, the moisture can be removed by discharging the solvent-containing water containing the solvent from the gravity settling tank 7 to the pressure vessel 11 for solvent separation. it can.

  Further, the solvent separation pressure vessel 11 may be connected to the slurry adjusting tank 3 by a pipe or the like. When handling coal containing a lot of moisture, the slurry adjustment tank 3 is heated to 100-120 ° C. near the boiling point of water to evaporate and recover moisture from the coal, and the moisture in the slurry sent to the extraction process This is because the concentration can be reduced. The solvent-containing water generated here can be supplied from the slurry adjusting tank 3 to the solvent separation pressure vessel 11 to be separated into the solvent and water.

  A tank may be installed in the middle of the pipe 25 connected to the solvent separation pressure vessel 11. In the tank, the solvent-containing water is once condensed into a liquid (the solvent-containing water is condensed by lowering the temperature of the solvent-containing water), and then heated again to a temperature higher than the boiling point of the water. Evaporate water from the water. The vapor | steam (solvent is mixed) which concentrated the water concentration obtained by this is sent to the pressure vessel 11 for solvent separation from the said tank. By this step, the solvent concentration in the solvent-containing water sent to the solvent separation pressure vessel 11 is reduced, and the solvent loss rate can be further reduced. The solvent remaining in the tank is extracted from the tank and reused.

  Here, the method for producing ashless coal (process for producing ashless coal) includes an extraction step, a separation step, and an ashless coal acquisition step. Hereinafter, a method for separating the solvent-containing water produced in the process of producing ashless coal into a solvent and water will be described while explaining each of these steps. In addition, there is no restriction | limiting in particular in the coal used as a raw material in manufacture of ashless coal, You may use bituminous coal with a high extraction rate (ashless coal recovery rate), and cheaper inferior quality coal (subbituminous coal, lignite) It may be used. The ashless coal means ash content of 5% by weight or less, preferably 3% by weight or less.

(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. In this embodiment, this extraction process mixes coal and a solvent to prepare a slurry, and heats the slurry prepared in the slurry preparation process to extract coal components soluble in the solvent ( It is divided into a solvent-soluble component extraction step (which is dissolved in a solvent).

  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) Alternatively, 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. Since this non-hydrogen donating solvent is stable even in a heated state and has an excellent affinity with coal, a high ratio of soluble components (here, coal components) extracted into the solvent is high. In addition, it 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.

  The specific gravity of these solvents (ratio with the weight of water of the same volume) is about 1 at room temperature (normal temperature).

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

<Slurry preparation process>
The slurry preparation step is performed 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.

<Solvent soluble component extraction process>
The solvent-soluble component extraction step is performed in the preheater 5 and the extraction tank 6 in FIG. The slurry prepared in the slurry preparation tank 3 is once supplied to the preheater 5 by the transfer pump 4 and heated to a predetermined temperature, then supplied to the extraction tank 6, and stirred at the predetermined temperature while being stirred by the stirrer 6a. It is retained and extracted.

  The heating temperature of the slurry in the solvent-soluble component extraction step is not particularly limited as long as the solvent-soluble component can be dissolved. From the viewpoint of sufficient dissolution of the solvent-soluble component and improvement of the extraction rate, for example, 300 to 420 It is 360 degreeC, 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.

  The solvent-soluble component 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.

(Method for separating solvent and water)
As described above, in the extraction of the coal component, the slurry is heated to a temperature of, for example, 300 to 420 ° C. Here, under such a high temperature, coal undergoes a thermal decomposition reaction, and methane (CH ₄ ), carbon dioxide (CO ₂ ), water (H ₂ O), and the like are generated. In addition, since the raw material coal originally contains water and water is insoluble in the solvent, the water is separated from the coal when the coal component is extracted by the solvent.

(Solvent-containing water supply process)
The solvent-containing water supply step is a step of supplying solvent-containing water to the pressure vessel for solvent separation. Water generated from coal by thermal decomposition (H 2 _O), and moisture separated from the coal upon extraction of coal components (H 2 _O) is in gaseous state containing a solvent (state of the solvent-containing steam), the tube 25 And supplied (discharged) to the pressure vessel 11 for solvent separation. Since the temperature in the solvent separation pressure vessel 11 is lower than the temperature in the extraction tank 6, the water vapor is condensed into a liquid.

(Temperature holding process)
The temperature holding step is a step of holding the temperature of the solvent-containing water supplied to the solvent separation pressure vessel 11 at a predetermined temperature, and is performed in the solvent separation pressure vessel 11 in FIG. The solvent-containing water supplied from the extraction tank 6 to the solvent separation pressure vessel 11 is constant in the solvent separation pressure vessel 11 so that the difference between the water density and the solvent density becomes constant. Heated by the heater 11a. For example, the temperature is maintained at a temperature of 100 ° C. or higher and 180 ° C. or lower (a predetermined temperature in a temperature range of 100 to 180 ° C.). Thereby, due to the difference between the density of water and the density of the solvent at the temperature, the liquid water descends to the lower part in the solvent separation pressure vessel 11 and the liquid solvent rises to the upper part in the solvent separation pressure vessel 11. By doing so, the solvent and water are separated. In order to improve the separability between the solvent and water, it is preferable that the solvent-containing water is allowed to stand for a predetermined time. In addition, the solvent separation pressure vessel 11 is preferably kept warm by a heat insulating material in order to keep the temperature of the solvent-containing water at a predetermined temperature or higher. “Standing” refers to placing in a stationary state without stirring.

  The solvent collected in the upper part of the solvent separation pressure vessel 11 is extracted from the upper part of the solvent separation pressure vessel 11, and the water accumulated in the lower part of the solvent separation pressure vessel 11 is removed from the solvent separation pressure vessel 11. Extracted from the bottom. The extracted solvent is returned to the solvent tank 2 and reused, and the extracted water is discarded.

  Moreover, it is preferable to perform a temperature holding process in presence of inert gas, such as nitrogen. That is, the solvent separation pressure vessel 11 is preferably filled with an inert gas such as nitrogen. The pressure in the solvent separation pressure vessel 11 is set to a pressure higher than the saturated vapor pressure of water so that the water condensed by the condensation of water vapor is kept in a liquid state, for example, nitrogen gas into the pressure vessel. The pressure is adjusted to 0.3 to 2.0 MPa by introduction.

  In addition, after the solvent-containing water supplied to the solvent separation pressure vessel 11 is stirred with a stirrer or the like, the stirring may be stopped when the water becomes constant at a predetermined temperature, and left still.

  In the extraction tank 6, the slurry is heated to a temperature of 300 to 420 ° C., for example. If the temperature of the solvent-containing water supplied from the extraction tank 6 to the solvent separation pressure vessel 11 can be maintained at a temperature of 120 ° C. or higher for a predetermined time without heating, the heater 11a is unnecessary. .

(When there is no extraction tank 6)
In some cases, the extraction tank 6 may be omitted and a solvent-soluble coal component may be extracted in a tube between the preheater 5 and the gravity settling tank 7. For example, assuming that the pipe between the preheater 5 and the gravity settling tank 7 is of a length sufficient for the extraction of the coal components, the extraction of the coal components within the pipe between the preheater 5 and the gravity settling tank 7 is performed. Do. Coal is directly supplied into a pipe through which a heated high-temperature (for example, 380 ° C.) solvent flows between the preheater 5 and the gravity settling tank 7. In this case, the solvent separation pressure vessel 11 is connected to the gravity settling tank 7, the solvent-containing water is supplied (discharged) from the gravity settling tank 7 to the solvent separation pressure vessel 11, and the solvent-containing water is mixed with the solvent and water. And to separate.

Return to the manufacturing process of ashless coal.
(Separation process)
The separation step is a step of separating a solution containing a coal component dissolved in a solvent from the slurry obtained in the extraction step. In other words, the separation step is a step of separating the slurry obtained in the extraction step into a solution containing a coal component dissolved in a solvent and a solvent-insoluble component concentrate (solid content concentrate). This separation step is performed in the gravity settling tank 7 in FIG. The slurry obtained in the extraction step is separated by gravity into a supernatant liquid as a solution and a solid content concentrated liquid in the gravity sedimentation tank 7 (gravity sedimentation method). The supernatant liquid in the upper part of the gravity settling tank 7 is discharged to the solvent separator 9 through the filter unit 8 as necessary, and the solid concentrate settled in the lower part of the gravity settling tank 7 is sent to the solvent separator 10. Discharged.

  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 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.

  The gravity settling tank 7 is preferably kept warm, heated, or pressurized in order to prevent reprecipitation of solvent-soluble components eluted from coal. The 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 for separating the solution containing the coal component dissolved in the solvent from the slurry obtained in the extraction step, there are a filtration method, a centrifugal separation method, and the like in addition to the gravity sedimentation method.

(Ashless coal acquisition process)
The ashless coal acquisition step is a step of obtaining ashless coal by evaporating and separating the solvent from the solution (supernatant liquid) separated in the separation step described above. This ashless charcoal acquisition process is performed by the solvent separator 9 in FIG.

  As a method for separating the solvent from the solution (supernatant liquid), a general distillation method or an evaporation method can be used. For example, a flash distillation method is used. The separated and recovered solvent can be circulated to the slurry preparation tank 3 and used repeatedly. By separating and recovering the solvent, ashless charcoal (HPC) substantially free of ash (for example, 3% by weight or less of ash) can be obtained from the supernatant. Ashless coal contains almost no ash, has no moisture, and exhibits a higher calorific value than raw coal. Furthermore, the softening and melting property, which is a particularly important quality as a raw material for coke for iron making, has been greatly improved, and the obtained ashless coal (HPC) has good softening and melting properties even if the raw material coal does not have softening and melting properties. Have Therefore, ashless coal can be used, for example, as a blended coal for coke raw materials.

(By-product coal acquisition process)
The by-product charcoal acquisition step is a step for obtaining by-product charcoal by evaporating and separating the solvent from the solvent-insoluble component concentrate (solid content concentrate) separated in the gravity sedimentation tank 7. This byproduct charcoal acquisition step is also a step for recovering the solvent by evaporating and separating it from the solid concentrate, and is performed by the solvent separator 10 in FIG. 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 or evaporation method can be used as in the above-described ashless coal acquisition step. The separated and recovered solvent can be circulated to the slurry preparation tank 3 and used repeatedly. By separation and recovery of the solvent, by-product coal (also referred to as RC or residual coal) in which solvent-insoluble components including ash and the like are concentrated can be obtained from the solid concentrate. 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. The by-product coal may be discarded without being collected.

(Example)
An experiment was conducted to separate solvent-containing water into solvent and water. FIG. 2 is a diagram for explaining an outline of a separation test for separating solvent-containing water into a solvent and water. 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. Distilled water was used as water.

  A vertically long autoclave 50 used in the experiment is a cylindrical pressure vessel having a diameter of 62.3 mm, and as shown in FIG. 2, a structure that allows liquid to escape from the bottom of the autoclave 50 and a plurality of locations at a predetermined height from the bottom. It is said. The liquid sampling was performed at a total of six locations of 0 mm, 170 mm, 380 mm, 590 mm, 700 mm, and 800 mm with the bottom of the autoclave 50 being 0 mm in height. Further, a stirrer 50 a is installed inside the autoclave 50. The autoclave 50 was filled with nitrogen gas, and the pressure in the autoclave 50 was adjusted to 1.5 MPa.

  Solvent: 1200 g and water: 1200 g were placed in the autoclave 50. At room temperature (room temperature), the solvent and water were mixed, and the separability was very poor. That is, at room temperature (normal temperature), there is almost no difference between the density of water and the density of the solvent.

  While stirring the mixed solution composed of the solvent and water, the temperature was raised to a predetermined temperature. The temperature conditions were 50 ° C, 90 ° C, 100 ° C, 120 ° C, 150 ° C, and 200 ° C. Stirring was stopped when the temperature of the liquid mixture became constant at a predetermined temperature. After stopping stirring, the mixture was allowed to stand for 30 minutes. And the liquid was taken out from the autoclave 50 to the sampling containers 51a-51f, and the moisture concentration of the liquid was measured. The results are shown in Table 1. FIG. 3 is a graph showing the results shown in Table 1. The vertical axis represents the height from the bottom of the autoclave 50, and the horizontal axis represents the water concentration.

  As can be seen from Table 1 and FIG. 3, when the holding temperature is 50 ° C., the moisture concentration repeatedly increases and decreases in the height direction of the autoclave 50, and the tendency that the solvent and the water are separated even visually is not so much. I was not able to admit. In the case of 90 ° C. and 200 ° C., the water concentration was low at the top of the autoclave 50, but the water concentration at the bottom was not sufficiently high (the solvent was mixed), so the separation performance was low.

  On the other hand, when the holding temperature is 100 ° C., 120 ° C., and 150 ° C., the moisture concentration is low at the top of the autoclave 50 and high at the bottom, and the moisture concentration ranges from 400 mm to 600 mm from the bottom. A major change was observed. This shows that when the holding temperature is 100 ° C., 120 ° C., and 150 ° C., the solvent separation performance is high. In particular, at 150 ° C., the bottom moisture content was 98% by weight, which is the highest. From this, it was found that the temperature range where the holding temperature is 150 ° C. is the best temperature range as the solvent separation condition.

  This separation test showed that the difference between the density of water and the density of the solvent varies greatly with temperature (it depends greatly on temperature). The present invention makes use of this property that has been found.

(Action / Effect)
The solvent separation method of the present invention comprises a temperature maintaining step for maintaining the temperature of the solvent-containing water supplied to the pressure vessel for solvent separation at a predetermined temperature, and the difference between the water density and the solvent density at the predetermined temperature. The solvent-containing water is separated into the solvent and the water by lowering the liquid water and raising the solvent in the pressure vessel for solvent separation. A pressure vessel is used to confine water in the liquid phase in the vessel. According to the present invention, by maintaining the temperature of the solvent-containing water at a predetermined temperature in the pressure vessel, the solvent-containing water can be easily separated into the solvent and water without using an adsorbent or the like. As a result, the adsorbent can be recovered and reused for the extraction of the coal component, so that the loss of the solvent can be suppressed and the water disposal cost can also be suppressed. Note that the solvent-containing water supply step of supplying the solvent-containing water to the solvent separation pressure vessel may be performed continuously or discontinuously.

  Moreover, in the said temperature holding process, the separation performance of a solvent and water can be improved by hold | maintaining the temperature of solvent containing water at predetermined temperature, and leaving solvent containing water still.

  In the temperature holding step, the temperature of the solvent-containing water in the pressure vessel for solvent separation is maintained at a temperature of 100 ° C. or higher and 180 ° C. or lower, so that the separation performance of the solvent and water becomes very good, and the separation time Can be shortened. There is also an advantage that the capacity of the pressure vessel for solvent separation can be reduced. More preferably, the temperature of the solvent-containing water in the solvent separation pressure vessel is maintained at a temperature of 120 ° C. or higher and 150 ° C. or lower.

  In addition, since the pressure in the solvent separation pressure vessel is higher than the saturated vapor pressure of water, water can be reliably trapped in the liquid phase in the pressure vessel, and the solvent and water can be separated. The performance is further improved.

  Further, since the inert gas is filled in the pressure vessel for solvent separation, the explosion of the solvent can be prevented.

  Moreover, it is preferable to supply the solvent containing water which arises at an above-described extraction process among the processes which manufacture ashless coal to the pressure vessel for solvent separation. Most of the water is generated in the extraction step of the process for producing ashless coal. At least the solvent-containing water generated in this extraction step is supplied to the pressure vessel for solvent separation, and the solvent-containing water is mixed with the solvent and water. By separating into two, it is possible to reliably suppress the loss of the solvent mixed into the moisture and discharged out of the system.

  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 Solvent separator 11: Pressure for solvent separation Container 100: Ashless coal production facility

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 a solution containing a coal component soluble in a solvent from the slurry obtained in the extraction step;
Ashless coal acquisition step of obtaining ashless coal by evaporating and separating the solvent from the solution separated in the separation step;
A solvent separation method for separating solvent-containing water produced in a process for producing ashless coal into a solvent and water,
A solvent-containing water supply step of supplying the solvent-containing water to a pressure vessel for solvent separation;
A temperature maintaining step for maintaining the temperature of the solvent-containing water supplied to the pressure vessel for solvent separation at a temperature of 100 ° C. or higher and 180 ° C. or lower ;
With
Due to the difference between the density of water and the density of the solvent at a temperature of 100 ° C. or higher and 180 ° C. or lower , the liquid water is lowered and the solvent is raised in the solvent separation pressure vessel, whereby the solvent-containing water is mixed with the solvent. Solvent separation method characterized by separating into water. The solvent separation method according to claim 1,
In the temperature maintaining step, the temperature of the solvent-containing water is maintained at a temperature of 100 ° C. or higher and 180 ° C. or lower, and the solvent-containing water is allowed to stand still. The solvent separation method according to claim 1 or 2 ,
The solvent separation method, wherein a pressure in the solvent separation pressure vessel is higher than a saturated vapor pressure of water. In the solvent separation method in any one of Claims 1-3 ,
A solvent separation method, wherein the solvent separation pressure vessel is filled with an inert gas. In the solvent separation method in any one of Claims 1-4 ,
A solvent separation method comprising supplying the solvent-containing water produced in the extraction step to a pressure vessel for solvent separation in a process for producing ashless coal.

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