Ashless coal manufacturing method and ashless coal manufacturing device

Abstract

To provide a method of manufacturing an ashless coal and an apparatus for manufacturing an ashless coal, capable of improving an extraction rate of a solvent soluble component of a coal.SOLUTION: A method of manufacturing an ashless coal includes: a preparation step of mixing a coal, a solvent, hydrogen, and a formic acid to prepare a slurry; an elution step of eluting a solvent soluble component of the coal in the solvent of the slurry; a separation step of separating from the slurry a solution in which the solvent soluble component is eluted in the solvent at the elution step; and an evaporation step of evaporating the solvent from the solution separated at the separation step.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for producing ashless coal and an apparatus for producing ashless coal. [Background technology]

[0002] High-strength coke is used as coke for steelmaking, such as blast furnace coke. To obtain high-strength coke, so-called strong coking coal, which has high caking properties, has traditionally been used as the raw coal. However, because strong coking coal is relatively expensive, techniques for reducing the amount of strong coking coal used are currently being considered.

[0003] Attempts have been made to use ashless coal as raw coal that can produce high-strength coke while reducing the amount of heavily coking coal used. For example, Patent Document 1 proposes a method for producing this ashless coal, which uses a coal-derived solvent whose boiling point is within a predetermined temperature range. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-120185 Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Document 1 describes that by using a specific solvent, the solvent can be recycled without being discarded, and therefore ashless coal can be produced at relatively low cost. There is a need for a method of producing ashless coal at even lower cost, specifically, a method for further improving the extraction rate of solvent-soluble components from coal.

[0006] In view of the above circumstances, an object of the present invention is to provide a method for producing ashless coal and an apparatus for producing ashless coal that can improve the extraction rate of solvent-soluble components of coal. [Means for solving the problem]

[0007] A method for producing ashless coal according to one embodiment of the present invention that solves the above-mentioned problems includes a preparation process of mixing coal, a solvent, hydrogen, and formic acid to prepare a slurry; an elution process of eluting solvent-soluble components of the coal into the solvent of the slurry; a separation process of separating from the slurry a solution in which the solvent-soluble components have been eluted into the solvent in the elution process; and an evaporation process of evaporating the solvent from the solution separated in the separation process.

[0008] Another aspect of the present invention, which solves the above-mentioned problem, provides an ashless coal manufacturing apparatus comprising: a preparation unit that mixes coal, a solvent, hydrogen, and formic acid to prepare a slurry; an elution unit that dissolves solvent-soluble components of the coal into the solvent of the slurry; a separation unit that separates the solution in which the solvent-soluble components have dissolved into the solvent from the slurry; and an evaporation unit that evaporates the solvent from the separated solution. [Effects of the Invention]

[0009] The method for producing ashless coal and the apparatus for producing ashless coal of the present invention can improve the extraction rate of solvent-soluble components of coal. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a conceptual diagram showing an apparatus for producing ashless coal according to one embodiment of the present invention. [Figure 2] FIG. 2 is a flow diagram showing a method for producing ashless coal according to one embodiment of the present invention using the production apparatus of FIG. [Figure 3] FIG. 3 is a conceptual diagram showing an apparatus for producing ashless coal that is different from that shown in FIG. [Figure 4] FIG. 4 is a graph comparing the extraction rates of soluble components of coal dissolved in the solvent in the slurry. [Figure 5] FIG. 5 is a graph comparing the thermoplasticity of soluble components of coal dissolved in a solvent in a slurry. [Figure 6]FIG. 6 is a graph comparing the thermoplasticity of coal-soluble components dissolved in a solvent in slurries obtained under conditions different from those of the sample in FIG. [Figure 7] FIG. 7 is a graph comparing the thermoplasticity of coal soluble components with temperature changes when the mole fraction of formic acid in a mixed gas of hydrogen and formic acid is changed. [Figure 8] FIG. 8 is a graph comparing the thermoplasticity of coal soluble components with changes in the molar fraction of formic acid in a mixed gas of hydrogen and formic acid. DETAILED DESCRIPTION OF THE INVENTION

[0011] A method for producing ashless coal according to one embodiment of the present invention includes a preparation process for mixing coal, a solvent, hydrogen, and formic acid to prepare a slurry; an elution process for eluting solvent-soluble components of the coal into the solvent of the slurry; a separation process for separating from the slurry a solution in which the solvent-soluble components have been eluted into the solvent in the elution process; and an evaporation process for evaporating the solvent from the solution separated in the separation process.

[0012] In the method for producing ashless coal, in the preparation step, coal, a solvent, hydrogen, and formic acid are mixed to prepare a slurry, and in the leaching step, solvent-soluble components of the coal are eluted into the solvent of the slurry. This makes it possible to improve the extraction rate of the solvent-soluble components of the coal in the leaching step. Specifically, coal generates radicals (coal radicals) when heated. If these coal radicals are present, the coal undergoes polycondensation and becomes polymeric in the leaching step, resulting in an insufficient extraction rate of the solvent-soluble components. In the method for producing ashless coal, the slurry contains the formic acid, which makes it possible to stabilize the coal radicals. This makes it possible to suppress polycondensation of coal caused by the coal radicals and improve the extraction rate of the solvent-soluble components. Furthermore, in the method for producing ashless coal, hydrogen is further added to the slurry, making it possible to easily add hydrogen radicals to the coal. The addition of these hydrogen radicals further suppresses coal polycondensation and further improves the extraction rate of the solvent-soluble components.

[0013] The preparation step preferably includes a treatment step of treating coal with hydrogen and formic acid, and a mixing step of mixing the coal after the treatment step with the solvent. In this way, a slurry containing hydrogen and formic acid can be easily produced.

[0014] In the treatment step, the coal is preferably stored in an atmosphere of a mixed gas of hydrogen and formic acid, which makes it easier to produce a slurry containing hydrogen and formic acid.

[0015] The molar fraction of formic acid in the mixed gas of hydrogen and formic acid is preferably 5% or more and 10% or less. By setting the molar fraction of formic acid within this range, the extraction rate of solvent-soluble components of coal can be further improved.

[0016] It is preferable to raise the temperature of the coal in the slurry in the mixing step, which makes it even easier to extract the solvent-soluble components of the coal in the leaching step.

[0017] Another aspect of the present invention relates to an apparatus for producing ashless coal, and includes a preparation unit that mixes coal, a solvent, hydrogen, and formic acid to prepare a slurry, an elution unit that dissolves solvent-soluble components of the coal into the solvent of the slurry, a separation unit that separates the solution in which the solvent-soluble components have dissolved into the solvent from the slurry, and an evaporation unit that evaporates the solvent from the separated solution.

[0018] In the ashless coal production apparatus, a slurry is generated by mixing coal, a solvent, hydrogen, and formic acid in a preparation section that prepares the slurry, and the formic acid can stabilize coal radicals in the coal in the slurry, and the hydrogen can add hydrogen radicals to the coal. This effectively suppresses polycondensation of the coal and improves the extraction rate of the solvent-soluble components of the coal in the leaching section.

[0019] The preparation unit preferably includes a solvent storage tank for storing the solvent, a coal storage tank for storing the coal, a formic acid supplier for supplying formic acid to the coal storage tank, and a hydrogen supplier for supplying hydrogen to the coal storage tank. This allows the coal before being slurried to come into contact with a mixed gas of hydrogen and formic acid in advance, facilitating mixing in the preparation unit.

[0020] The preparation unit preferably includes a solvent storage tank for storing the solvent, a mixing tank for storing the coal and the formic acid, and a hydrogen supplier for supplying the hydrogen to the mixing tank. This allows the coal before being slurried to come into contact with a gas mixture of hydrogen and formic acid, facilitating mixing in the preparation unit.

[0021] [Details of the Mode for Carrying Out the Invention] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that with regard to the numerical values ​​described in this specification, it is possible to arbitrarily combine the described upper limit values ​​and lower limit values. In this specification, it is assumed that all numerical ranges from the upper limit values ​​to the lower limit values ​​that can be combined are described as suitable ranges. Furthermore, the diagrams showing the ashless coal production apparatus conceptually or schematically show each component (each component), and the shape, scale, etc. of the actual components are different.

[0022] [First embodiment] <Ashless coal manufacturing equipment> As shown in FIG. 1 , an ashless coal production apparatus 1 (hereinafter also referred to as "production apparatus 1") according to one embodiment of the present invention mainly includes a preparation unit 2 that mixes coal (not shown), a solvent T, hydrogen H, and formic acid F to prepare a slurry Y, an elution unit 3 that elutes solvent-soluble components of the coal into the solvent T of the slurry Y, a separation unit 4 that separates a solution L in which the solvent-soluble components have been eluted into the solvent T from the slurry Y, and an evaporation unit 5 that evaporates the solvent T from the separated solution L. The evaporation unit 5 is configured to evaporate the solvent T from the separated solution L. The ashless coal C H a first evaporator 51 for obtaining by-product coal C S and a second evaporation section 52 for obtaining the

[0023] 〔coal〕 The type of coal is not particularly limited, and examples thereof include bituminous coal and inferior coals (such as subbituminous coal or lignite) that are cheaper than bituminous coal. Among these, by using bituminous coal as the coal, ashless coal C H This can further improve the production efficiency of the coal. The particle size of the coal is not particularly limited, but finely pulverized coal, for example, coal with a particle size of 1 mm or less, is preferably used. Lump coal can also be used as the coal. Lump coal has a large particle size, which can improve the efficiency of separation in the separation section 4. Note that "lump coal" refers to coal in which the mass ratio of coal with a particle size of 5 mm or more to the total mass of coal is 50% or more. Furthermore, "particle size (particle size)" refers to a value measured in accordance with the general rules for sieving tests of JIS-Z8815 (1994). For example, a metal mesh sieve specified in JIS-Z8801-1 (2019) can be used to sieve the coal.

[0024] It is also preferable to use low fluidity coal having a maximum fluidity of less than 1000 ddpm as the coal. By using the low fluidity coal as the coal, ashless coal C H While maintaining the production efficiency of ashless coal C H The manufacturing cost can be reduced.

[0025] 〔solvent〕 The solvent T is not particularly limited as long as it can elute the solvent-soluble components of the coal. For example, a bicyclic aromatic compound derived from coal is preferably used. This bicyclic aromatic compound has a basic structure similar to that of the structural molecules of coal, and therefore has a high affinity with coal, allowing a relatively high elution rate to be obtained. Examples of the coal-derived bicyclic aromatic compound include methylnaphthalene oil and naphthalene oil, which are distilled by-products obtained when carbonizing coal to produce coke.

[0026] The boiling point of solvent T is not particularly limited, but for example, the lower limit of the boiling point of solvent T is preferably 180°C, more preferably 230°C. On the other hand, the upper limit of the boiling point of solvent T is preferably 300°C, more preferably 280°C. If the boiling point of solvent T is below the above lower limit, solvent T will be more likely to volatilize, which may make it difficult to adjust and maintain the mixing ratio of the components in slurry Y. On the other hand, if the boiling point of solvent T exceeds the above upper limit, it may become difficult to easily separate solvent T from the solvent-soluble components of the coal in evaporation section 5.

[0027] [Preparation Department] The preparation unit 2 has a solvent storage tank 21 that stores a solvent T and a coal storage tank 22 that stores the coal. The preparation unit 2 of this embodiment has a formic acid supplier 23 that supplies formic acid F to the coal storage tank 22, and a hydrogen supplier 24 that supplies hydrogen H to the coal storage tank 22.

[0028] The preparation section 2 also has a solvent supplier 25 for pumping the solvent T stored in the solvent storage tank 21, and a heater for heating the solvent T pumped by the solvent supplier 25. The heater is a preheater 26 that heats the solvent T to obtain a heated slurry Y.

[0029] (Solvent storage tank) The solvent storage tank 21 is a tank for storing the solvent T. The solvent storage tank 21 is not particularly limited, and examples thereof include known liquid tanks. The solvent storage tank 21 may be configured to be supplied with the solvent T3 discharged from the evaporation section 5 described later. In this way, ashless coal C can be produced at low cost. H can be manufactured.

[0030] (Solvent supplier) The solvent supplier 25 is disposed in a solvent supply line P1 that connects the solvent reservoir tank 21 with a mixing pipe 27 (described later). The solvent supplier 25 is not particularly limited, and examples thereof include well-known positive displacement pumps and non-positive displacement pumps. An example of the non-positive displacement pump is a centrifugal pump.

[0031] (preheater) The preheater 26 is disposed in the solvent supply line P1 downstream of the solvent supply unit 25. The preheater 26 is not particularly limited, and examples thereof include known resistance heaters and induction heating coils. Alternatively, the preheater 26 may be one that uses a heat medium for heating.

[0032] The lower limit of the temperature of solvent T after heating (preheating) by the preheater 26 is preferably 300°C, more preferably 350°C. On the other hand, the upper limit of the temperature of solvent T is preferably 480°C, more preferably 450°C. If the temperature of solvent T is below the lower limit, the bonds between the molecules that make up the coal may not be sufficiently weakened, and the solvent-soluble components of the coal may not be sufficiently extracted. On the other hand, if the temperature of solvent T exceeds the upper limit, the amount of heat required to maintain the temperature of solvent T becomes unnecessarily large, and the ashless coal C H This may increase the manufacturing cost.

[0033] (Coal storage tank) The coal storage tank 22 stores the coal, and also supplies mixed coal C, which is a mixture of hydrogen H and formic acid F, to a mixing pipe 27 described later via a coal supply line P2. R The coal storage tank 22 is not particularly limited, and examples thereof include a known atmospheric pressure hopper or a pressure hopper.

[0034] (Formic acid supplier) The formic acid supplier 23 supplies formic acid F to the coal storage tank 22 via a formic acid supply line P3. The formic acid F is supplied in a gaseous state to the coal storage tank 22. The formic acid supplier 23 includes a liquid tank for storing liquid formic acid F, a heater (not shown) for heating and vaporizing the liquid formic acid F, and a gas pump (not shown) for delivering the vaporized formic acid F.

[0035] The temperature for vaporizing formic acid F is not particularly limited, but for example, the lower limit is preferably 20° C., more preferably 25° C. The upper limit of the temperature for vaporizing formic acid F is preferably 50° C., more preferably 40° C. It is preferable to provide a heater (not shown) such as a ribbon heater in the formic acid supply line P3 so that formic acid F is stably supplied to the coal storage tank 22 in a gaseous state.

[0036] (Hydrogen supply unit) The hydrogen supplier 24 supplies hydrogen H to the coal storage tank 22 via a hydrogen supply line P4. The hydrogen H is supplied in a gaseous state to the coal storage tank 22. The hydrogen supplier 24 is not particularly limited, and examples thereof include a known gas tank that stores gaseous hydrogen H at high pressure. The hydrogen supply line P4 is preferably provided with an on-off valve (not shown) for arbitrarily starting and stopping the supply of hydrogen H. The hydrogen supplier 24 and the hydrogen supply line P4 each preferably have a heater (not shown) or the like so that hydrogen H can be supplied at the same temperature as formic acid F.

[0037] [Mixing tube] The preparation unit 2 receives the solvent T sent from the solvent storage tank 21 and the mixed coal C sent from the coal storage tank 22. R The mixing tube 27 supplies the slurry Y to the elution section 3, which will be described later.

[0038] Since hydrogen H and formic acid F are supplied to the coal storage tank 22 in a gaseous state, the mixed coal C that was in an atmosphere of the mixed gas of hydrogen H and formic acid F is mixed in the mixing tube 27. R The heated solvent T and the mixed coal C are mixed to prepare a slurry Y. In the mixing tube 27, the heated solvent T and the mixed coal C are mixed. R By mixing these, a slurry Y having a temperature of 300° C. or higher is generated. The mixing pipe 27 may have a heater (not shown) capable of maintaining the temperature of the slurry Y or heating the slurry Y.

[0039] The lower limit of the coal concentration in the slurry Y based on dry coal is preferably 5% by mass, more preferably 10% by mass. On the other hand, the upper limit of the coal concentration is preferably 40% by mass, more preferably 30% by mass. If the coal concentration is below the lower limit, the amount of elution of the solvent-soluble components of the coal in the elution tank 31 described below will be small relative to the amount of slurry Y processed. H Conversely, if the coal concentration exceeds the upper limit, the solvent-soluble components of the coal may become saturated in the solvent T, resulting in a decrease in the elution rate of the solvent-soluble components.

[0040] In the manufacturing apparatus 1, mixed coal C is mixed with a heated solvent T. R Since it is mixed with mixed coal C R The temperature of the coal is rapidly increased. Generally, rapid heating of coal causes polycondensation due to coal radicals. However, in the production apparatus 1, the coal is stored in an atmosphere of a mixed gas containing formic acid F, which stabilizes the coal radicals that are generated when the coal is heated. As a result, polycondensation of the coal caused by coal radicals is suppressed, and the extraction rate of the solvent-soluble components of the coal is improved. Furthermore, in the production apparatus 1, the coal is stored in an atmosphere of a mixed gas containing hydrogen H, which adds hydrogen radicals to the coal, further suppressing polycondensation of the coal and further improving the extraction rate of the solvent-soluble components of the coal. Note that "rapid heating" refers to heating at a heating rate of, for example, 10°C / s or more and 500°C / s or less. The temperature of the slurry Y after this rapid heating is, for example, 350°C or more and 420°C or less.

[0041] [Elution part] The leaching unit 3 elutes the solvent-soluble components of the coal into the solvent T in the slurry Y. The leaching unit 3 has a leaching tank 31 connected downstream of the mixing pipe 27. The leaching tank 31 is a tank for storing the slurry Y, and includes an agitator 311 and a heater (not shown) for maintaining the temperature of the slurry Y or for heating the slurry Y. The slurry Y mixed in the mixing pipe 27 is sent to the leaching tank 31.

[0042] (Elution tank) In the leaching tank 31, the temperature of the slurry Y sent from the mixing tube 27 is maintained by the heater, and the slurry Y is stirred by the agitator 311. By stirring the slurry Y at a predetermined temperature, the solvent-soluble components of the coal are eluted into the solvent T.

[0043] The lower limit of the internal pressure of the leaching tank 31 is preferably 1.1 MPa, more preferably 1.5 MPa. On the other hand, the upper limit of the internal pressure of the leaching tank 31 is preferably 5 MPa, more preferably 4 MPa. If the internal pressure of the leaching tank 31 is below the lower limit, the solvent T will be reduced by evaporation, resulting in the coal C R On the other hand, if the internal pressure exceeds the upper limit, the cost of maintaining the pressure increases, and the ashless coal C H This may increase the manufacturing cost.

[0044] The stirring time in the elution tank 31 is not particularly limited, but can be set to 10 minutes or more and 70 minutes or less from the viewpoint of the elution efficiency of the solvent-soluble components.

[0045] The slurry Y stirred in the elution tank 31 is supplied to the separation section 4 via a slurry supply line P5.

[0046] [Separation part] The separation unit 4 separates a solution L in which the solvent-soluble components have been dissolved in the solvent T from the slurry Y. The separation unit 4 includes a solid-liquid separator 41 that uses a centrifugal separation method, a gravity settling method, or the like. The separation unit 4 separates the slurry Y sent from the elution tank 31 into a solution L in which the solvent-soluble components have been dissolved in the solvent T and a solids concentrated liquid M containing the solvent-insoluble components and the solvent T. The separation unit 4 supplies the solution L to a first evaporator 51 via a solution supply line P6, and supplies the solids concentrated liquid M to a second evaporator 52 via a concentrated liquid supply line P7.

[0047] (solid-liquid separator) The solid-liquid separator 41 in the separation section 4 is preferably an apparatus using gravity settling, which can increase the settling rate and improve separation efficiency. Gravity settling is also preferable from the viewpoint of enabling continuous processing of the slurry Y. When separating the slurry Y by gravity settling, the solution L containing the solvent-soluble components accumulates in the upper part of the separation section 4. This solution L is filtered using a filter unit as necessary and then supplied to the first evaporator 51. On the other hand, the solids concentrated liquid M containing the solvent-insoluble components accumulates in the lower part of the separation section 4 and is supplied to the second evaporator 52.

[0048] The inside of the solid-liquid separator 41 is preferably heated and pressurized. The lower limit of the heating temperature in the solid-liquid separator 41 is preferably 300°C, more preferably 350°C. On the other hand, the upper limit of the heating temperature in the solid-liquid separator 41 is preferably 420°C, more preferably 400°C. If the heating temperature is below the lower limit, the solvent-soluble components may be reprecipitated, and the separation efficiency may decrease. On the other hand, if the heating temperature exceeds the upper limit, the cost for heating increases, and the ashless coal C H This may increase the manufacturing cost.

[0049] The lower limit of the internal pressure of the solid-liquid separator 41 is preferably 1 MPa, more preferably 1.4 MPa. On the other hand, the upper limit of the internal pressure is preferably 3 MPa, more preferably 2 MPa. If the internal pressure is below the lower limit, the solvent-soluble components may be reprecipitated, resulting in a decrease in separation efficiency. On the other hand, if the internal pressure exceeds the upper limit, the cost of pressurization may increase.

[0050] [Evaporation section] The evaporation section 5 has a first evaporator 51 that evaporates the solvent T1 from the solution L separated in the separation section 4. The first evaporator 51 evaporates the solvent T in the solution L to precipitate the solvent-soluble components. The precipitated solvent-soluble components are used to produce ashless coal C produced by the production apparatus. H The evaporation section 5 has a second evaporator 52 that evaporates the solvent T2 from the solids-concentrated liquid M separated in the separation section 4. The second evaporator 52 evaporates the solvent T2 in the solids-concentrated liquid M to produce by-product coal C. Sis precipitated.

[0051] The evaporation section 5 has a first discharge line P8 for discharging the solvent T1 evaporated in the first evaporator 51, a second discharge line P9 for discharging the solvent T2 evaporated in the second evaporator 52, and a recycling line 53 for supplying the discharged solvents from the first discharge line P8 and the second discharge line P9 to the preparation section 2.

[0052] (First evaporator) The first evaporator 51 evaporates the solvent T in the solution L to convert the solvent-soluble components into ashless coal C. H The ashless coal C precipitated in the first evaporator 51 H For example, ashless coal C has a higher calorific value than raw coal. H The thermoplasticity, which is an especially important quality for a raw material for coke in steelmaking, has been significantly improved, and for example, it exhibits fluidity far superior to that of raw coal. H is suitably used as raw coal to be blended with coke raw materials.

[0053] The first evaporator 51 may be configured to evaporate the solvent T by a general distillation method using, for example, an evaporation separation method, or may be configured to evaporate the solvent T by an evaporation method such as a spray drying method.

[0054] (Second evaporator) The second evaporator 52 evaporates the solvent T from the concentrated solids solution M to produce by-product coal C S The second evaporator 52 may be configured to evaporate the solvent T by an evaporation method such as an evaporation separation method or a spray drying method, similar to the first evaporator 51.

[0055] By-product coal C precipitated in the second evaporator 52 S Although by-product coal C does not exhibit thermoplasticity, since the oxygen-containing functional groups have been eliminated, when it is used as a coal blend, it does not inhibit the thermoplasticity of other coals contained in the coal blend. Therefore, this coal blend can also be used as part of a coal blend for coke raw materials. S may be disposed of without recovery.

[0056] (First discharge line) The first discharge line P8 discharges the solvent T evaporated in the first evaporator 51 to the recycle line 53. The first discharge line P8 may have a heat exchanger (not shown) for liquefying the discharged solvent T1.

[0057] (Second discharge line) The second discharge line P9 discharges the solvent T evaporated in the second evaporator 52 to the recycle line 53. The second discharge line P9 may have a heat exchanger (not shown) for liquefying the discharged solvent T2.

[0058] (Recycling line) The reuse line 53 supplies the solvent T3, which is a mixture of the discharged solvent T1 sent from the first discharge line P8 and the discharged solvent T2 sent from the second discharge line P9, to the solvent storage tank 21. That is, in the manufacturing apparatus 1, the solvent T is recycled by refluxing.

[0059] <Manufacturing method of ashless coal> As shown in Figure 2, the method for producing ashless coal (hereinafter also referred to as "the production method") includes a preparation step S1 of preparing a slurry by mixing coal, a solvent, hydrogen, and formic acid, an elution step S2 of eluting solvent-soluble components of the coal into the solvent of the slurry prepared in the preparation step S1, a separation step S3 of separating from the slurry a solution in which the solvent-soluble components have been eluted into the solvent, and an evaporation step S4 of evaporating the solvent from the solution separated in the separation step S3. In this embodiment, the preparation step S1 includes a treatment step of treating coal with hydrogen and formic acid, and a mixing step of mixing the coal after the treatment step with the solvent.

[0060] In the evaporation step S4, the solvent is evaporated to precipitate the solvent-soluble component. The precipitated solvent-soluble component is the ashless coal produced by the production method.

[0061] Below, each step of the manufacturing method will be described in detail using the manufacturing apparatus 1 of FIG. 1 as an example.

[0062] [Preparation process] The preparation step S1 is carried out in the preparation unit 2. In the preparation step S1, the coal, the solvent T, the hydrogen H, and the formic acid F are mixed to prepare a slurry.

[0063] (Processing process) In the preparation step S1, first, formic acid F and hydrogen H are treated with the coal. Specifically, a formic acid supplier 23 and a hydrogen supplier 24 supply formic acid F and hydrogen H in a gaseous state to a coal storage tank 22 in which the coal is stored, thereby impregnating the coal with formic acid F and hydrogen H to produce a mixed coal C. R get.

[0064] The lower limit of the temperature of the mixed gas of formic acid F and hydrogen H in the coal storage tank 22 is preferably 20° C., more preferably 25° C. On the other hand, the upper limit of the temperature of the mixed gas is preferably 50° C., more preferably 40° C. If the temperature of the mixed gas is not within the range between the lower limit and the upper limit, it may not be possible to stably maintain the vaporized state of formic acid F.

[0065] (Mixing process) Subsequently, in the preparation step S1, mixed coal C treated with hydrogen H and formic acid F in the coal storage tank 22 is R The coal is mixed with the solvent T supplied from the solvent storage tank 21 and heated in the preheater 26 in a mixing tube 27. That is, in the preparation step S1, the slurry Y is prepared by two-stage mixing: a treatment step in which the coal is treated with hydrogen H and formic acid F, and a mixing step in which this mixture is mixed with the solvent T.

[0066] (heating process) In the preparation step S1, the solvent T is heated by the preheater 26 to prepare the mixed coal C. R That is, in this embodiment, the temperature of the coal is increased by mixing the heated solvent T and the mixed coal C. R By mixing the above, a heated slurry Y is produced.

[0067] [Elution process] The leaching step S2 is performed in the leaching unit 3. In the leaching step S2, the slurry Y generated in the mixing tube 27 and supplied to the leaching tank 31 is stirred in the leaching tank 31 while maintaining or increasing the temperature of the slurry Y. In the leaching step S2, the solvent-soluble components of the coal are eluted into the solvent T by keeping the slurry Y warm and stirring it. The temperature of the slurry Y in the leaching step S2 is 300°C or higher, and preferably 350°C to 420°C. By maintaining such a temperature, the solvent-soluble components of the coal can be efficiently eluted.

[0068] When the coal is heated to 300°C or higher, it generates coal radicals, but the presence of formic acid F during heating can stabilize the coal radicals. Specifically, the coal radicals can be stabilized by supplying hydrogen and electrons to the coal through the reaction represented by the following formula 1. As a result, polycondensation of the coal caused by coal radicals can be suppressed, and the extraction rate of the solvent-soluble components of the coal can be improved. Furthermore, supplying hydrogen H to the coal and adding hydrogen radicals further suppresses polycondensation of the coal, and the extraction rate of the solvent-soluble components of the coal can be further improved. HCOOH→CO2+2H + +2e - ···(1)

[0069] [Separation process] The separation step S3 is carried out in the separation section 4. In the separation step S3, the slurry Y treated in the elution step S2 is subjected to solid-liquid separation using a method such as centrifugation or gravity settling into a solution L in which the solvent-soluble components are eluted into the solvent T and a concentrated solids liquid M containing the solvent-insoluble components and the solvent T.

[0070] [Evaporation process] The evaporation step S4 is performed in each of the first evaporator 51 and the second evaporator 52. In the evaporation step S4, the first evaporator 51 evaporates the solvent T in the solution L separated in the separation step S3, and the solvent-soluble components are separated into ashless coal C. H Ashless coal C obtained by evaporation step S4 HThe second evaporator 52 evaporates the solvent T in the solids concentrated liquid M separated in the separation step S3, and produces by-product coal C. S is precipitated.

[0071] In addition to the above-mentioned steps, the production method also includes a first solvent recovery step of discharging and recovering the solvent T evaporated in the evaporation step S4, a second solvent recovery step of discharging and recovering the solvent T contained in the solid concentrate M from the solid concentrate M separated in the separation step S3, and a recycling step of reusing the solvents recovered in the first solvent recovery step and the second solvent recovery step in the preparation step S1. Hereinafter, an example of specific procedures for the first solvent recovery step, the second solvent recovery step, and the recycling step will be described.

[0072] [First solvent recovery process] The first solvent recovery step is performed in the first discharge line P8. In the first solvent recovery step, the solvent T evaporated in the evaporation step S4 is discharged into the first discharge line P8, and the discharged solvent T1 is sent to the reuse line 53. In the first solvent recovery step, the discharged solvent T1 may be liquefied and then sent to the reuse line 53.

[0073] <Second solvent recovery process> The second solvent recovery step is performed in the second discharge line P9. In the second solvent recovery step, the solvent T evaporated in the evaporation step S4 is discharged into the second discharge line P9, and the discharged solvent T2 is sent to the reuse line 53. In the second solvent recovery step, the discharged solvent T2 may be liquefied and then sent to the reuse line 53.

[0074] <Reuse process> The recycling step is carried out in a recycling line 53. In the recycling step, the discharged solvent T1 recovered in the first solvent recovery step and the discharged solvent T2 recovered in the second solvent recovery step are supplied to a solvent storage tank 21. The solvent T3 supplied to the solvent storage tank 21 is reused as part of the solvent T in the preparation step S1.

[0075] <Advantages> The manufacturing apparatus 1 and the manufacturing method include a mixed coal C obtained by treating the coal with hydrogen H and formic acid F in a preparation step S1 in a preparation unit 2. R and heated solvent T to generate slurry Y, and in elution step S2 in elution unit 3, the soluble components of the coal are eluted into solvent T of slurry Y, thereby improving the extraction rate of the solvent-soluble components of the coal. H can be efficiently manufactured, and costs can be reduced.

[0076] [Second embodiment] Hereinafter, an ashless coal manufacturing apparatus 100 and a method for manufacturing ashless coal according to another embodiment of the present invention will be described. Note that the same components as those in the ashless coal manufacturing apparatus 1 and the ashless coal manufacturing method according to the first embodiment described above will be denoted by the same reference numerals in the drawings, and descriptions thereof will be omitted.

[0077] 3, the manufacturing apparatus 100 mainly includes a preparation unit 200 that mixes coal, a solvent T, hydrogen, and formic acid to prepare a slurry Y, an elution unit 3 that elutes solvent-soluble components of the coal into the solvent T in the slurry Y, a separation unit 4 that separates a solution L in which the solvent-soluble components have been eluted into the solvent T from the slurry Y, and an evaporation unit 5 that evaporates the solvent T from the separated solution L. The evaporation unit 5 is configured to evaporate the solvent T from the separated solution L. H a first evaporator 51 for obtaining by-product coal H S and an evaporation section 52 for obtaining the

[0078] [Preparation Department] The preparation unit 200 includes a solvent storage tank 21 for storing a solvent T, a mixing tank 201 for mixing the coal, formic acid F, and hydrogen H, and a mixed coal C that has been treated with formic acid F and hydrogen H. R to the mixing pipe 27, and a hydrogen supplier 204 that supplies hydrogen H to the mixing vessel 201. The preparation unit 200 also includes a hydrogen supply line P10 that connects the hydrogen supplier 204 and the mixing vessel 201, a mixing vessel line P11 that connects the mixing vessel 201 and the coal supplier 202, and a coal supply line P12 that connects the coal supplier 202 and the mixing pipe 27.

[0079] (mixing tank) The mixing tank 201 stores the coal and liquid formic acid F. Specifically, the coal is stored in the mixing tank 201 so as to be immersed in formic acid F in the form of a formic acid aqueous solution or a formic acid compound. A hydrogen supplier 204 supplies gaseous hydrogen H to the mixing tank 201 via a hydrogen supply line P10. Specifically, an outlet of the hydrogen supply line P10 is provided in the liquid formic acid F, and hydrogen H is supplied into the formic acid F by bubbling. In this way, the coal is treated with formic acid F and hydrogen H, and mixed coal C is obtained. R is generated.

[0080] The upper limit of the mixing temperature of the coal and formic acid F in the mixing tank 201 is preferably 80°C, more preferably 60°C. On the other hand, the lower limit of the mixing temperature is preferably 20°C, more preferably 25°C. If the mixing temperature exceeds the upper limit, the amount of volatilization of formic acid F increases, and there is a risk that the solvent-soluble components of the coal cannot be sufficiently eluted into the solvent T in the elution tank 31. If the mixing temperature is below the lower limit, the viscosity of formic acid F increases, and the mixed coal C R This may result in a decrease in handling ability.

[0081] Mixed coal C after mixing in mixing tank 201 R The upper limit of the content of formic acid F in the ashless coal C (the ratio of the mass of formic acid F to the total mass of the coal and formic acid F) is preferably 6% by mass, more preferably 3% by mass. H On the other hand, the lower limit of the content of formic acid F is not particularly limited, but from the viewpoint of sufficiently increasing the extraction rate of the solvent-soluble components of the coal, it is, for example, preferably 0.2% by mass, and more preferably 0.5% by mass.

[0082] (coal feeder) The coal feeder 202 feeds the mixed coal C supplied from the mixing tank 201. RThe coal is temporarily stored and supplied to the mixing pipe 27. As with the coal storage tank 22 described above, the coal supplier 202 may be, for example, a known atmospheric pressure hopper or pressure hopper.

[0083] In the manufacturing apparatus 100, the coal is treated with liquid formic acid F and hydrogen H to produce mixed coal C R The temperature is raised by mixing the coal with solvent T. When the coal is mixed with solvent T and heated to 300°C or higher, coal radicals are generated, but the presence of formic acid F during the temperature increase stabilizes the coal radicals. As a result, polycondensation of the coal caused by the coal radicals is suppressed, and the extraction rate of the solvent-soluble components of the coal can be improved. Furthermore, in the manufacturing apparatus 100, hydrogen H is mixed with the coal, so hydrogen radicals are added to the coal, which further suppresses polycondensation of the coal and further improves the extraction rate of the solvent-soluble components of the coal.

[0084] [Elution part] The leaching unit 3 elutes the solvent-soluble components of the coal into the solvent T in the slurry Y. The leaching unit 3 is connected downstream of the mixing pipe 27 and has a leaching tank 31 including an agitator 311.

[0085] [Separation part] The separation unit 4 separates the solution L in which the solvent-soluble components have been dissolved in the solvent T from the slurry Y. The separation unit 4 includes a solid-liquid separator 41 that uses a centrifugal separation method, a gravity settling method, or the like.

[0086] [Evaporation section] The evaporation section 5 evaporates the solvent T from the solution L separated in the separation section 4 to produce ashless coal C. H a first evaporator 51 for evaporating the solvent T from the solids concentrated liquid M separated in the separation section 4 to obtain by-product coal C; S The second evaporator 52 is used to obtain the

[0087] <Manufacturing method of ashless coal> The method for producing ashless coal (hereinafter also referred to as "the production method") includes a preparation step S1 of preparing a slurry by mixing coal, a solvent, hydrogen, and formic acid, an elution step S2 of eluting solvent-soluble components of the coal into the solvent in the slurry prepared in the preparation step S1, a separation step S3 of separating from the slurry a solution in which the solvent-soluble components have been eluted into the solvent, and an evaporation step S4 of evaporating the solvent from the solution separated in the separation step S3. At least one of the preparation step S1 and the elution step S2 also includes a heating step S11 of raising the temperature of the slurry.

[0088] Below, each step of the manufacturing method will be described in detail using the manufacturing apparatus shown in FIG. 3 as an example.

[0089] [Preparation process] The preparation step S1 is performed in the preparation unit 2. In the preparation step S1, first, in order to treat the coal with formic acid F and hydrogen H, a hydrogen supplier 204 supplies hydrogen H to a mixing tank 201 storing liquid formic acid F and the coal, and the mixed coal C is R Generate.

[0090] Next, in the preparation step S1, the mixing tank 201 supplies the mixed coal C to the coal feeder 202. R The coal feeder 201 supplies the mixed coal C R The mixed coal C is supplied to the mixing tube 27. R The coal is mixed with a solvent T supplied from the solvent storage tank 21 and heated in the preheater 26. That is, in the preparation step S1, the slurry Y is prepared by two-stage mixing: treatment of the coal with hydrogen H and formic acid F, and mixing of this mixture with the solvent T.

[0091] [Elution process] The elution step S2 is performed in the elution section 3. In the elution step S2, the slurry Y is mixed in the mixing tube 27, and then stirred in the elution tank 31 while maintaining the temperature of the slurry Y.

[0092] [Separation process] The separation step S3 is carried out in the separation section 4. In the separation step S3, the slurry Y treated in the elution step S2 is subjected to solid-liquid separation using a method such as centrifugation or gravity settling into a solution L in which the solvent-soluble components are eluted into the solvent T and a concentrated solids liquid M containing the solvent-insoluble components and the solvent T.

[0093] [Evaporation process] The evaporation step S4 is performed in the first evaporator 51. In the evaporation step S4, the solvent T1 in the solution L separated in the separation step S3 is evaporated, and the solvent-soluble components are dissolved in the ashless coal C. H It is precipitated as

[0094] [Other embodiments] The above-described embodiments do not limit the configuration of the present invention. Therefore, the above-described embodiments may include omissions, substitutions, or additions of components based on the description in this specification and common general technical knowledge, and all of these should be construed as falling within the scope of the present invention.

[0095] In the first embodiment described above, the formic acid supplier 23 has been described as including a liquid tank for storing liquid formic acid F, a heater for heating and vaporizing the liquid formic acid F, and a gas pump for delivering the vaporized formic acid F. However, the formic acid supplier 23 may also include a gas tank for storing gaseous formic acid F at high pressure and an on-off valve.

[0096] Furthermore, in the first embodiment, formic acid F and hydrogen H may be supplied in a mixed gas state to the coal storage tank 22. For example, a part of the formic acid supply line P3 and a part of the hydrogen supply line P4 may be integrated before the coal storage tank 22, and the mixed gas may be supplied to the coal storage tank 22 at this integrated part. Furthermore, hydrogen H may be bubbled into a liquid tank that stores formic acid F in a liquid state, and the mixed gas of formic acid F and hydrogen H may be supplied from the liquid tank to the coal storage tank 22.

[0097] Furthermore, instead of reusing both the solvents T1 and T2 discharged to the first discharge line P8 and the second discharge line P9 in the preparation unit 2, only one of the discharged solvents may be recovered and reused. In addition, the reuse line 53 may be configured to perform a fractional distillation process on both or either of the solvent T1 discharged to the first discharge line P8 and the solvent T2 discharged to the second discharge line P9, and then supply the distilled solvent to the solvent storage tank 21.

[0098] The manufacturing method does not necessarily have to include the first solvent recovery step, the second solvent recovery step, and the recycling step. In this case, the manufacturing apparatus does not necessarily have to include the first discharge line P8, the second discharge line P9, and the recycling line 53. Furthermore, when the manufacturing method includes only one of the first solvent recovery step and the second solvent recovery step, the manufacturing apparatus only needs to include either the first discharge line P8 corresponding to the first solvent recovery step or the second discharge line P9 corresponding to the second solvent recovery step.

[0099] In the preparation step, the coal and the solvent T may be mixed to form a slurry, and then hydrogen H and formic acid F may be mixed into the slurry. For example, hydrogen H and formic acid F may be bubbled into the slurry. In this case, the temperature of the slurry may be increased after the hydrogen H and formic acid F are mixed into the slurry.

[0100] The temperature-raising step is not limited to heating the solvent T in the preheater 26, but may involve producing the slurry Y in the mixing tube 27 and then raising the temperature of the slurry Y with a heater provided in the mixing tube 27, or may involve raising the temperature of the slurry Y with a heater provided in the elution tank 31. The temperature of the slurry Y may be raised in either the preparation step or the elution step, or in both. [Example]

[0101] The present invention will be described in detail below based on examples, but the present invention should not be construed as being limited by the descriptions in these examples.

[0102] 0.3 g of bituminous coal (sample coal) that had been sieved to have a particle size of less than 150 μm was placed on an alumina boat, which was then placed in a quartz tube and treated under the conditions shown in Table 1 below.

[0103] [Table 1]

[0104] In Table 1, "-" indicates that no treatment was performed or that the value could not be measured. "Tb" indicates the temperature of the gas supplied into the quartz tube. "Atmosphere" indicates the atmosphere inside the quartz tube. "Tr" indicates the final temperature to which the inside of the quartz tube was heated. The temperature inside the quartz tube was increased at a rate of 10°C / min, and the sample charcoal was held at the final temperature (Tr) for 90 minutes.

[0105] The sample coal was mixed with a solvent to form a slurry, which was then stirred to dissolve the soluble components of the sample coal into the solvent. The solvent used was 1-methylnaphthalene, an industrial bicyclic aromatic compound. The sample coal slurry was subjected to solvent extraction fractionation at 350 °C, separating the coal into three components: soluble components (extracted at 350 °C and soluble in the solvent at room temperature), deposit components (extracted at 350 °C but precipitated as a solid at room temperature), and residue components (not extracted at the extraction temperature). The separation results are shown in Figure 4. The term "solvent extraction fractionation" refers to a method for extracting coal and modified coal (ashless coal) with a nonpolar solvent, separating and evaluating multiple components with different molecular weights without decomposing the coal molecules.

[0106] It can be seen that compared to untreated raw coal (Test Example 1), the extract yield (sum of soluble and deposit yields) is improved in Test Examples 2 and 3. Test Example 3, in which the temperature inside the quartz tube was set to 110°C, increased the extract yield by 15% on a dry coal basis and 44% on an extract basis compared to Test Example 1.

[0107] Thermomechanical analysis was performed on the components (soluble and deposit) extracted at 350°C. Each extracted component was deposited to a thickness of approximately 1 mm in a platinum cell with an inner diameter of 5.3 mm. The sample was heated to 900°C at a rate of 10°C / min in a nitrogen stream while applying a load of 10 gf with a 4.3 mm diameter rod, and the change in the rod's position from its initial position was measured. The results are shown in Figures 5 and 6.

[0108] 5 and 6, it can be seen that Test Examples 2 and 3, which were treated in a mixed atmosphere of hydrogen and formic acid, had a lower rod position in thermomechanical analysis and improved softening and melting properties compared to untreated Test Example 1, Test Example 4, which was treated in a hydrogen atmosphere, and Test Example 5, which was treated in a mixed atmosphere of nitrogen and formic acid.

[0109] Next, thermomechanical analysis was performed by changing the molar fraction of formic acid in the mixed gas of hydrogen and formic acid. The results are shown in Figures 7 and 8. Figures 7 and 8 show that the thermoplasticity changes from decreasing to increasing at a molar fraction of formic acid of 7.5%. [Industrial Applicability]

[0110] The method and apparatus for producing ashless coal of the present invention can increase the extraction rate of solvent-soluble components of coal, and are therefore suitable for the efficient production of ashless coal. [Explanation of symbols]

[0111] 1,100 Ashless coal manufacturing equipment 2,200 Preparation Department 21 Solvent storage tank 22 Coal storage tank 23 Formic acid supplier 24,204 Hydrogen supply 25 Solvent supply 26 Preheater 27 Mixing tube 201 Mixing tank 202 Coal feeder 3 Elution part 31 Elution tank 311 Stirrer 4 Separation part 41 Solid-liquid separator 5 Evaporation section 51 First evaporator 52 Second evaporator 53 Recycle Line C R mixed coal C H Ashless coal C S By-product charcoal F formic acid H Hydrogen L solution M solids concentrate P1 Solvent supply line P2 Coal Supply Line P3 Formic Acid Supply Line P4 Hydrogen supply line P5 Slurry supply line P6 Solution supply line P7 Concentrate supply line P8 First discharge line P9 Second discharge line P10 Hydrogen supply line P11 Mixing tank line P12 Coal supply line T, T3 solvent T1, T2 Discharge solvent Y Slurry

Claims

1. a preparation step of mixing coal, a solvent, hydrogen, and formic acid to prepare a slurry; a leaching step of leaching a solvent-soluble component of the coal into the solvent of the slurry; a separation step of separating a solution in which the solvent-soluble components have been dissolved into the solvent in the elution step from the slurry; an evaporation step of evaporating the solvent from the solution separated in the separation step; A method for producing ashless coal comprising:

2. The preparation step comprises: treating the coal with hydrogen and formic acid; a mixing step of mixing the coal after the treatment step with the solvent; The method for producing ashless coal according to claim 1, comprising:

3. The method for producing ashless coal according to claim 2, wherein in the treatment step, the coal is stored in an atmosphere of a mixed gas of hydrogen and formic acid.

4. The method for producing ashless coal according to claim 3, wherein the molar fraction of the formic acid in the mixed gas is 5% or more and 10% or less.

5. The method for producing ashless coal according to claim 2, claim 3, or claim 4, wherein the temperature of the coal in the slurry is increased in the mixing step.

6. a preparation unit that mixes coal, a solvent, hydrogen, and formic acid to prepare a slurry; an elution section that elutes a solvent-soluble component of the coal into the solvent of the slurry; a separation unit that separates a solution in which the solvent-soluble component is dissolved in the solvent from the slurry; an evaporation section for evaporating the solvent from the separated solution; An ashless coal manufacturing apparatus comprising:

7. The preparation unit a solvent storage tank for storing the solvent; a coal storage tank for storing the coal; a formic acid supplier for supplying formic acid to the coal storage tank; a hydrogen supplier for supplying hydrogen to the coal storage tank; The apparatus for producing ashless coal according to claim 6, comprising:

8. The preparation unit a solvent storage tank for storing the solvent; a mixing tank for storing the coal and the formic acid; a hydrogen supply device for supplying the hydrogen to the mixing vessel; The apparatus for producing ashless coal according to claim 6, comprising:

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