AU746500B2 - Process of coal liquefaction - Google Patents

Description

P/00/0 11 Regulation 3.2

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

a a a TO BE COMPLETED BY APPLICANT :::Name of Applicant: *:.Actual Inventor(s): Address for Service: Invention Title: The following statement is performing it known to me ~ce 5 sbs cA.,-,eVAkw c4 0(OYA NIPPON BROWN COAL LIQuE+ACTION COe., LTD.

I De y,6so'<0J C Cc~ '-,COV\O oN C0V\vq0'7t1- IWON! OOv Nobuyuki Komatsu; Mitsushi Kishimoto; Toshiaki Okui; Masaaki Tamura CALLINAN LAWRIE, 711 High Street, Kew, 3101, Victoria, Australia "PROCESS OF COAL LIQUEFACTION" a full description of this invention, including the best method of 5/2/98LP9522. CS, I INVENTION TITLE PROCESS OF COAL LIQUEFACTION BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a process for coal liquefaction, and more specifically, to a technical field concerning a process for coal liquefaction including the raw material preparing step for mixing a solvent into raw coal to obtain a slurry mixture and the hydrogenating step for adding hydrogen to the mixture to hydrogenate coal.

Description of the Related Art The technical development relating to a fuel as a substitute for petroleum has been earnestly desired with a petroleum crisis experienced twice so far as a turning point.

9.

Particularly, in view of abundant coal reserves, it is important to establish techniques of efficiently liquefying coal to obtain a fuel oil.

There have been proposed a variety of processes for coal 9.

liquefaction. As a typical process for coal liquefaction, 0999 e othere can be mentioned a process for coal liquefaction including the raw material preparing step for mixing a solvent and a catalyst to pulverized raw coal to obtain a slurry mixture, the hydrogenating step for adding a hydrogen gas to the mixture under high temperatures and high pressures to hydrogenate coal, and the oil separating step for -A separating oil from the hydrogenation product obtained by the hydrogenating step. As the oil separating step mentioned herein, there can be employed generally the gas-liquid separating step for feeding the hydrogenation product to a gas-liquid separator, removing unnecessary gases such as CO,

CO

2 and the like by the reduction operation through the gasliquid separator, and separating a gas-phase fraction and a liquid-phase fraction. The obtained liquid-phase fraction is regulated in its range of boiling point by distillation step or the like and recovered as the product oil, a part of which is recycled and supplied to the raw material preparing step and used as a solvent (a so-called recycle solvent) mixed into the raw coal.

In the process for coal liquefaction as described, it is economically advantageous to make higher the concentration of coal in the slurry mixture. However, the high concentration of coal results in the high viscosity of the slurry mixture, g. thus making the handling thereof difficult. For this reason, the concentration of coal in the slurry mixture is set to a level not harming the handling of the mixture. In the **conventional method for coal liquefaction, the concentration of coal is low. Particularly, in the case of brown coal, since pore structure is developed, a part of solvent is ::absorbed into the pores of brown coal so that the viscosity of the slurry mixture is high. Therefore, it is often that ee** the concentration of coal in the slurry mixture is limited to a low concentration, say, 28 to 35 mass (weight and it was necessary to set the concentration of coal to such a low level as described above. Therefore, in the case of the conventional process for coal liquefaction, the quantity of coal that can be processed relative to the volume of a reactor is less so that the efficiency of apparatus volume is low, the efficiency of contact between coal and a catalyst is low, and the yield of liquefied oil is low.

That is, it is important, in terms of enhancing the efficiency of transportation and the efficiency of volume, to increase the concentration of coal in the slurry mixture (hereinafter merely referred to as the slurry) containing the solvent and coal prepared in the raw material preparing step.

When the concentration of coal in the slurry is increased, the efficiency of contact between the catalyst and coal is enhanced. Therefore, the liquefaction reactivity can be expected to be enhanced. Incidentally, as a solvent used when the slurry is obtained, there is generally used a solvent (a recycle solvent) adjusted in the range of boiling point by distilling oil (coal liquefied oil) separated the hydrogenation product. However, a part of the solvent is absorbed into the pores of raw coal so that the viscosity of the slurry is high, and particularly in the case of brown coal, since pore structure is developed, a part of solvent is .absorbed into the pores so that the viscosity of the slurry S. mixture tends to be higher than the case where other kind of coal is used.

In consideration of the discharge performance of a slurry feed pump from a raw material making vessel to a preheater and a reactor in a plant in an industrial scale of -3- I- I 1 1 7 114 W 110:11 the process for coal liquefaction, the viscosity of slurry capable of being fed is less than about 500 mPa.s at a temperature of 100 0 C. It has been confirmed that in the case where coal in which Australian brown coal is adjusted in water less than 15 mass and grain size less than meshes is used as raw coal and a fraction of coal liquefied oil obtained from the coal at 180 0 C to 420 0 C is used as a solvent to adjust the slurry, it is not possible to have the viscosity less than a limit slurry capable of being fed unless the concentration of coal in the slurry is a low concentration of about 28 to 35 mass (mass of solvent: about 1.8 to 2.5 times with respect to the mass of coal in dry ash of raw coal). At the concentration of coal in the slurry, the efficiency of contact between coal and catalyst when coal is liquefied lowers so that not only the reactivity is low but also the processing quantity of coal per hour is small. This increases the capacity of liquid to be fed by the feed pump and the internal volume of a hydrogenation reactor, which is not efficient.

SUMMARY OF THE INVENTION The present invention was accomplished in view of the foregoing. It is an object of the present invention to provide a process for coal liquefaction in which the impregnated amount of a solvent in raw coal in a slurry mixture is reduced as compared with the aforementioned conventional process for coal liquefaction by which the amount of solvent necessary for securing the viscosity within the limit viscosity of the slurry mixture capable of being fed will suffice to be small and the concentration of coal in the slurry mixture can be increased without affecting the feed of liquid, as a consequence of which the efficiency of contact between coal and catalyst is improved, the yield of liquefied oil can be improved, the processing amount of coal per time and per capacity in hydrogenation increases, coal capable of being processed with respect to the capacity of a reactor is large in quantity, and the yield of apparatus volume can be increased.

For achieving the aforementioned object, the process for coal liquefaction according to the present invention employs a method for coal liquefaction set out in claims 1 to 7 as defined below. According to claim 1, there is provided a process for coal liquefaction including the raw material preparing step for mixing a solvent in raw coal to obtain a slurry mixture and the hydrogenating step for adding hydrogen to said mixture to hydrogenate coal, characterized by using a mixed solvent having less than 1.5 mass (weight of the content of oxygen comprising a mixture of a light oil and a heavy oil obtained by subjecting coal liquefied oil to hydrotreatment (the first invention).

According to claim 2, there is provided a process for coal liquefaction defined in claim 1, wherein the slurry mixture obtained by the raw material preparing step is preheated, the light oil in the mixed solvent in said mixture is separated by a gas-liquid separating operation to increase the concentration of slurry of said mixture, and the mixture is fed to said hydrogenating step (the second invention).

According to claim 3, there is provided a process for coal liquefaction defined in claim 2, wherein the mass of solvent in the slurry mixture fed to said hydrogenating step is 0.3 to 1.0 times the mass of raw coal in a moisture free and ash free state (the third invention). According to claim 4, there is provided a process for coal liquefaction defined in claim 2 or 3, wherein the amount of light oil in the mixed solvent of the light oil and the heavy oil used in said raw material preparing step is 30 to 70 mass (the fourth invention) According to claim 5, there is provided a process for coal liquefaction defined in claim 1,2, 3 or 4, wherein the mass of a solvent mixed with raw coal in said raw material preparing step is 1.0 to 1.5 times the mass of raw coal in a moisture free and ash free basis (the fifth invention). According to claim 6, there is provided a process for coal i liquefaction defined in claim 1, 2, 3, 4 or 5, wherein said raw coal is brown coal (the sixth invention). According to claim 7, there is provided a process 0 0for coal liquefaction defined in claim 1, 2, 3, 4, 5 or 6, wherein said light oil is co~o •00 light oil having a continuous boiling point distribution at less than 300 0 C, and 0o00 said heavy oil is heavy oil having a continuous boiling point distribution at 300 0 C to 420 0 C (the seventh invention).

The process for coal liquefaction according to claim 8 is the process for coal liquefaction as defined in anyone of claims 1 to 7, wherein a proportion of oxygen amount of an oxygen containing compound having oxygen as a hvdroxyl group -6ck9522dec7.speci with respect to the oxygen amount of the oxygen containing compound having oxygen contained in the mixed solvent, in which said oxygen content is less than 1.5 mass is less than 60 mass (the eighth invention).

In the process for coal liquefaction according to the present invention, the impregnated amount of a solvent in raw coal in a slurry mixture is reduced as compared with conventional process for coal liquefaction by which the amount of solvent necessary for securing the viscosity within the limit viscosity of the slurry mixture capable of being fed will suffice to be small and the concentration of coal in the slurry mixture can be increased without affecting the feed of liquid, as a consequence of which the efficiency of contact between coal and catalyst is improved, the yield of liquefied oil can be improved, the processing amount of coal per time and per capacity in hydrogenation increases, coal Scapable of being processed with respect to the capacity of a reactor is large in quantity, and the yield of apparatus volume can be increased or even if the volume of a reactor is made small, a sufficient amount of coal processing can be .**secured and a reactor can be miniaturized.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing an example of a process for coal liquefaction according to the present invention.

-7- Fig. 2 is a schematic view showing an example of a process for coal liquefaction according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention pertains to a process for coal liquefaction, which is carried out in the following manner.

Heavy oil obtained by hydrotreatment of coal liquefied oil obtained from coal as a raw material and light oil obtained by distilling the coal liquefied oil are mixed so that the mixture has 1.5 mass or less of the content of oxygen to make a mixed solvent. Thus, the obtained mixed solvent and a catalyst for coal liquefaction are mixed with pulverized raw coal (raw brown coal, etc.) to obtain a slurry mixture. Then, the hydrotreatment of coal liquefied oil means the processing for reacting the coal liquefied oil with hydrogen. By this *ii processing, hydrotreated oil (solvent) is obtained. The heavy oil obtained by being separated from the hydrotreated oil means the heavy oil obtained by hydrotreatment.

The heavy oil obtained by hydrotreatment of coal liquefied oil contains less oxygen containing compound having a hydroxyl group, a carbonyl group, an ether group and the like by the hydrotreatment. Therefore, when the heavy oil and light oil are mixed to provide the mixed solvent, which is mixed with the raw coal to provide the slurry mixture, the interaction between an oxygen containing functional group such as a hydroxyl group, a carbonyl group, an ether group and the like in the oxygen-containing compound of the solvent -8and an oxygen containing functional group such as a hydroxyl group, a carbonyl group, an ether group and the like possessed by constituent molecules of coal is weak, and the impregnated amount of solvent in coal reduces.

As will be understood from the embodiment of the present invention as described above, according to the process for coal liquefaction of the present invention, the impregnated amount of solvent in the raw coal in the slurry mixture reduces as compared with the conventional process for coal liquefaction. That is, in the process for coal liquefaction according to the present invention, unlike the conventional process for coal liquefaction, the mixed solvent obtained by mixing the light oil with the heavy oil obtained by hydrotreatment of coal liquefied oil so that it has 1.5 mass or less of the content of oxygen is used as the solvent (solvent for making slurry) in the raw material preparing step for mixing the solvent with the raw coal to obtain a ~slurry mixture, owing to which the interaction between the solvent (slurry making solvent) and coal reduces as compared with the conventional process for coal liquefaction and the impregnated amount of solvent in the raw coal in the slurry mixture reduces. For this reason, the amount of solvent necessary for securing the viscosity within the limit viscosity of the slurry mixture capable of being fed will suffice to be small, and the concentration of coal in the slurry mixture can be increased without affecting the feed of liquid. As a result, the efficiency of transportation is enhanced, the efficiency of contact between coal and catalyst is enhanced, the yield of liquefied oil is further -9enhanced, the processing amount of coal per time and per volume in the hydrogenation increases, coal capable of being processed with respect to the volume of a reactor is large in quantity, and the efficiency of apparatus volume can be enhanced (the first invention).

Further, the slurry mixture obtained by using the mixed solvent as the slurry making solvent in the raw material preparing step is preheated, and the light oil in the mixed solvent in the mixture is separated by the gas-liquid separating operation whereby the concentration of slurry of the mixture can be further enhanced. The slurry mixture having the high concentration of slurry can be fed to the hydrogenating step for hydrogenation, as a consequence of which the yield of liquefied oil, the processing amount of coal per time and per volume, and the efficiency of apparatus volume are further enhanced (the second invention) The invention will be described in more detail.

The inventors of the present invention have made intensive studies on the influence of properties of raw coal and solvent on the viscosity of the slurry (slurry mixture) o As a result, it has been found that particularly, in the case S. where brown coal is used as raw coal, since brown coal is low in carbonization degree, many oxygen containing functional groups such as a hydroxyl group, a carbonyl group, an ether group and the like are present in constituent molecules of brown coal, and when a recycle solvent (a solvent in which coal liquefied oil is distilled to adjust the boiling point range) used in the prior art as a solvent is mixed with the brown coal to provide a slurry, the interaction caused by the hydrogen bond of an oxygen containing functional group such as a hydroxyl group, a carbonyl group, an ether group and the like in the oxygen containing compound present in the solvent and an oxygen containing functional group in the brown coal occurs, owing to which the impregnation of solvent into the brown coal is accelerated and the viscosity of slurry rises accordingly.

Particularly, in the case where as a solvent mixed with the brown coal, a solvent in which coal liquefied oil obtained from brown coal as raw material is adjusted to a fraction of boiling point range 180 0 C to 420 0 C by distillation is used, the oxygen content in the solvent is not less than 3 mass and the oxygen is present in the solvent mainly in the form of an aromatic oxygen-containing compound such as phenol, benzofuran, cresol, etc. Therefore, the impregnation of solvent into brown coal is further accelerated and the viscosity of slurry is further risen. The 0* 0 content of oxygen in the solvent is high as described because, since brown coal which is low in carbonization degree is originally high in content of oxygen, not less than mass as compared with subbituminous coal and bituminous coal, many oxygen containing compounds are contained also in coal liquefied oil obtained from brown coal as raw material.

In view of the above, the present inventors have tried to reduce the content of oxygen in coal liquefied oil used as a solvent in order to lower the interaction between coal and solvent in the slurry, reduce the impregnated amount of -11solvent in coal and relieve an increase of slurry viscosity. The method for reducing the content of oxygen includes a method comprising: further hydrotreatment of coal liquefied oil (solvent) to thereby decompose and hydrogenate an oxygen-containing compound in the solvent, and removing oxygen atoms in the oxygen-containing compound in the form of water or CO, C02. A typical method for hydrotreatment of coal liquefied oil is a method comprising: for example, using a continuous fixed bed type high pressure reactor filled with an Ni-Mo catalyst or a Co-Mo catalyst as a catalyst, and processing coal liquefied oil under the conditions that temperature 3000C to 400 0 C, hydrogen pressure: 10 to 20 MPa, and LHSV (Liquid Hourly Space Velocity) 0.5 to 1.5 hr 1 to obtain a hydrotreated oil.

The coal liquefied oil obtained from brown coal as raw material is i subjected to hydrotreatment as described above, and the obtained product liquid (hydrotreatment oil) is adjusted to a fraction at 1800C to 4200C by distillation to obtain a product liquid. The content of oxygen in the product liquid was 0.5 to 1.5 mass depending on the hydrotreatment condition.

The product liquid having 1.2 mass of oxygen content as a solvent was mixed with the Australian brown coal to prepare a slurry. In the case where the concentration of coal in the slurry was 40 mass (mass of solvent 1.5 times mass of coal in a moisture free and ash free state, the slurry viscosity at IOO°C was approximately 210 mPaes. When the concentration of coal in the slurry was adjusted so as to correspond to the slurry -12viscosity of the liquid feed limit of 500 mPa-s, then the concentration of coal in the slurry was 48 mass (mass of solvent 1.08 times of mass of coal in a moisture free and ash free state), which is high in mass of coal as compared with the case where coal liquefied oil is used directly as a solvent for preparing slurry (the first invention).

Even if the concentration of coal in the slurry is made high, the slurry viscosity is low because the content of oxygen in the coal liquefied oil (solvent) is lowered by the hydrotreatment to thereby reduce the oxygen-containing compound in the solvent, owing to which the interaction between an oxygencontaining functional group such as a hydroxyl group, a carbonyl group, an ether group, etc. in the oxygen-containing compound of the solvent and an oxygen-containing functional group such as a hydroxyl group, carbonyl group, an ether group, etc. possessed by constituent molecules of brown coal see reduces to lower the impregnated amount of the solvent in brown coal.

In the case where the hydrotreatment conditions of the coal liquefied oil is relieved to make the content of oxygen in the solvent after the hydrotreatment 1.5 mass or more, and a slurry is prepared using the solvent, the slurry viscosity less than the liquid feed limit cannot be obtained unless the concentration of coal in the slurry is less than 40 mass (mass of solvent: not less than 1.5 times of mass of coal in a moisture free and ash free state).

Further, when a hydrotreated solvent less than content of oxygen less than mass is used, and the concentration of coal in the slurry is 50 mass or 13i' more (mass of solvent less than 1.0 times of mass of coal in a moisture free and ash free state), the slurry viscosity is often in excess of the liquid feed limit, which is not preferable. Accordingly, it is desired that the concentration of coal in the slurry in the raw material preparing step when the hydrotreated solvent of the content of oxygen less than 1.5 mass is used, is less than 50 mass (mass of solvent not less than 1.0 times in a moisture free and ash free state).

At that time, the concentration of coal in the slurry can be made 40 mass or more (mass of solvent less than 1.5 times of mass of coal in a moisture free and ash free state). By doing so, the concentration of coal is extremely high as compared with the prior art in which concentration of coal in the slurry is 28 to mass (mass of solvent: 1.8 to 2.5 times of mass of coal in a moisture free and ash free state of raw coal) It is therefore preferable that the concentration :II of coal in the slurry in the raw material preparing step is 40 to 50 mass (mass *of solvent 1.0 to 1.5 times of mass of coal in a moisture free and ash free state) (the fifth invention).

On the other hand, it has been obvious that from a viewpoint of coal liquefaction reaction, when heavy oil of boiling point range 300 0 C to 420 0 C is used as a solvent used for the liquefaction reaction, the coal liquefied oil obtained is rich in light fraction as compared with the case where the solvent of boiling point range 180 0 C to 420 0 C is used. Accordingly, it is desired that as a solvent used to prepare coal and slurry in the raw material preparing step, heavy oil of a hydrotreated solvent is used. The hydrotreated solvent is distilled to separate a fraction of boiling point range 300 0 C to 420 0 C to obtain heavy oil of the ST

P'

-14rli) hydrotreated solvent of content of oxygen 1.7 mass and a slurry is similarly prepared using the aforementioned Australian brown coal. Then, in the case where the concentration of coal in the slurry is adjusted with 40 mass (mass of solvent 1.5 times of mass of coal in a moisture free and ash free state), the slurry viscosity at 100°C is approximately 610 mPaos. Further, when the concentration of coal in the slurry is adjusted so as to correspond to the slurry viscosity of the liquid feed limit of 500 mPaes, the concentration of coal in the slurry is 35 mass (mass of solvent: 1.8 times of mass of coal in a moisture free and ash free state), which is apparently lower in concentration of coal than the case where the hydrotreated solvent of boiling point range 180C to 420 0 C is used. It is expected that at the concentration of coal as described, the efficiency of contact between catalyst and coal is low, and the :.:•:liquefying reactivity lowers.

i* In view of the foregoing, the present inventors have paid attention to the constitution of fraction of a solvent in the slurry preparing step in order to use heavy oil of the hydrotreated solvent and keep high the concentration of coal in the slurry fed to a hydrogenation reactor, and found that light oil of boiling point range: less than 300 0 C is mixed with the heavy oil of the hydrotreated solvent when slurry is prepared to lower the slurry viscosity, and the light oil portion in the solvent is separated by gas-liquid separating operation before the slurry enters the hydrogenation reactor whereby the solvent in the slurry can be concentrated substantially merely in the heavy oil of the hydrotreated solvent (the second invention). That is, as the slurry preparing solvent, a solvent having light oil of boiling point range less than 300 0 C and heavy oil of the hydrotreated solvent at 300 0 C to 420 0 C mixed is used; after the light oil has been fed from the raw material preparing step to the preheating step, the light oil is separated in the gas-liquid separating step in the vicinity of temperature 300 0 C whereby the slurry before being fed to the reactor substantially consists of coal and heavy oil; and since the environment is under the condition of high temperature not less than 300 0 C, even if the concentration of coal in the slurry is higher than 40 to 50 mass as described above, there is flowability so that material can be fed. In this case, it is necessary that in the mixed solvent of light oil and heavy oil used in the raw material preparing step, the content of oxygen in the solvent is less than 1.5 mass 9 because of reduction of interaction with the raw coal as previously mentioned. With respect to the light oil of 0* 0 boiling point range :less than 300 0 C, it is preferable to use a light component of the hydrotreated solvent. However, if the light oil has properties and a mixing ratio such that the S-content of oxygen in the solvent after being mixed with the heavy oil is less than 1.5 mass the hydrotreated solvent ,o.need not always be used.

mass of light oil of the hydrotreated solvent of boiling point range 180 0 C to 300 0 C, and content of oxygen 0.9 mass were mixed with 50 mass of heavy oil of the hydrotreated solvent of content of oxygen as mentioned above -16- 1.7 mass to obtain a mixed solvent of content of oxygen 1.3 mass and a slurry was prepared under the same conditions as the Australian brown coal as previously mentioned. In the case where the concentration of coal in the slurry is adjusted with 40 mass (mass of solvent: 1.5 times of mass of coal in a moisture free and ash free state), the slurry viscosity at 1 00C was approximately 350 mPaes. When the concentration of coal in the slurry was adjusted so as to correspond to the slurry viscosity of the liquid feed limit of 500 mPa-s, the concentration of coal in the slurry was 43 mass (mass of solvent: 1.3 times of mass of coal in a moisture free and ash free state) With this, the concentration of coal can be made higher than the case where heavy oil of the hydrotreated solvent is used. Further, when the light oil is separated by the gas-liquid separating operation after the preheating .I step using the slurry, the concentration of coal of the slurry was 61 mass (mass of solvent 0.65 time of mass of coal in a moisture free and ash free state), and the concentration of coal in the slurry fed to the hydrogenation reactor was considerably enhanced.

0000 It has been found that as described above, as the solvent for preparing the slurry in the raw material preparing step, a mixed solvent having light oil and heavy oil obtained by hydrotreatment of coal liquefied oil mixed so that the content of oxygen after mixing is less than 1.5 mass is used, whereby the impregnated amount of solvent in the raw coal in the slurry is reduced, owing to which the amount of solvent necessary for securing the viscosity within the limit viscosity of the slurry mixture capable of being fed 17will suffice to be small, and the concentration of coal in the slurry mixture can be made high without affecting the liquid feed.

It has been further found that the slurry mixture obtained in the raw material preparing step using the mixed solvent is preheated, and the light oil in the mixed solvent in the mixture is separated by the gas-liquid separating operation whereby the concentration of coal (concentration of slurry) in the slurry mixture can be made higher.

o.

It is desired that the amount of light oil in the mixed solvent of light oil and heavy oil used in the raw material preparing step is 30 to 70 mass i That is, when the amount of light oil in the mixed solvent is less than 30 mass the concentration of coal in the slurry after the light oil has been separated by the gas-liquid separating operation after preheating is less than 48 mass (mass of solvent 1.05 times or more of mass of coal in a moisture free and ash free state) so that the concentration of coal in the slurry fed to the hydrogenation reactor is not sufficiently high, the efficiency of contact between coal and catalyst is low, and the efficiency of liquefying reaction tends to lower. On the other hand, when the amount of light oil in the mixed solvent is mass or more, the concentration of coal in the slurry after separation of light oil in the gas-liquid separating operation after preheating is 77 mass or more (mass of solvent less than 0.3 time of mass of coal in a moisture free and ash free state) The flowability of slurry is poor even at a temperature of 300 0 C or more so that there is a tendency that feeding of slurry to -18the hydrogenation reactor is difficult. Accordingly, it is desired that the amount of light oil in the mixed solvent is 30 to 70 mass (the fourth invention) As will be apparent from the foregoing, it is desired that the mass of solvent in the slurry mixture fed to the hydrogenating step is 0.3 to 1.0 time of mass of coal in a moisture free and ash free state of raw coal (the third invention).

In the present invention, the mixed solvent in which oxygen content is less than 1.5 mass used as a slurry preparing solvent in the step of preparing raw material is a mixed solvent obtained by mixing light oil and heavy oil so that oxygen content after mixed is less than 1.5 mass as will be understood from the foregoing. That is, the above-described mixed :o solvent is obtained by mixing said light oil and said heavy oil so that the o amount of an oxygen containing compound after mixed is less than 1.5 mass in oxygen amount.

0 0o.0 The above oxygen containing compound is a compound having oxygen, that is, a compound having an oxygen containing group (for example, a hydroxyl group, a carbonyl group, an ether group, etc.). Such an oxygen containing compound includes a compound having oxygen as a hydroxyl group, a carbonyl group, an ether group, etc. Accordingly, it is said that the mixed solvent in which oxygen content is less than 1.5 mass is a mixed solvent in which the amount of a compound having oxygen as a hydroxyl group, a carbonyl group, an ether group, etc. is less than 1.5 mass -19- Ige.

As mentioned above, when a circulating solvent used in prior art is mixed with brown coal as a solvent to make a slurry, an interaction occurs due to a hydrogen bonding etc. of an oxygen containing functional group such as a hydroxyl group, a carbonyl group, an ether group etc. in the oxygen containing compound present in the solvent and an oxygen containing functional group in brown coal whereby an immersion of the solvent into the brown coal is accelerated, and a slurry viscosity is increased accordingly. It has been found as a result of further studies that of the oxygen containing functional groups in the oxygen containing compound, the hydroxyl group is strongest in the interaction caused by the hydrogen bonding etc. with the oxygen containing functional group in brown coal and serves to accelerate the immersion of the solvent into the brown coal and increase the slurry viscosity, and therefore, the reduction in the amount of particularly the oxygen compound having oxygen as a hydroxyl group out of *"the oxygen containing compounds of the solvent is effective for reduction in the interaction with the oxygen containing functional group of the brown coal, and for the lowering of .e the immersion amount of the solvent into the brown coal.

has been also found that in case of the mixed solvent in which the oxygen content is less than 1.5 mass when the amount of the oxygen containing compound having oxygen as a hydroxyl group is made to be less than 60 mass in oxygen amount with respect to the total of the oxygen containing compound, particularly, the immersion amount of the solvent into the brown coal, because of which the amount of the solvent necessary to secure the viscosity within the limit viscosity of the feedable slurry-like mixture is further reduced to further increase the concentration of coal in the slurry-like mixture without any trouble in feeding.

It is preferable from the aforementioned knowledge that in the mixed solvent in which the oxygen content is less than 1.5 mass a proportion of oxygen amount of an oxygen containing compound having oxygen as a hydroxyl group with respect to the oxygen amount of the oxygen containing compound having oxygen contained in the mixed solvent, in which said oxygen content is less than 1.5 mass is less than 60 mass (the eighth invention). That is, the mixed solvent in which oxygen content is less than *mass is preferable that a proportion of the amount of a compound having oxygen as a hydroxyl group with respect to 0.

the amount of an oxygen containing compound having oxygen as an oxygen containing functional group such as a hydroxyl group, a carbonyl group, an ether group, etc. is less than mass in amount of oxygen.

More specifically, the process for coal liquefaction according to the present invention is carried out by the apparatus and the process flow shown in Fig. i, and is carried out by the apparatus and the process flow shown in Fig. 2, details of which will be described with reference to these drawings.

In the case of using the apparatus shown in Fig. i, the process is carried out as follows. Dried and pulverized raw -21coal, light oil separated by a gas-liquid separator after a preheater and heavy oil obtained by being separated by a gas-liquid separator after hydrotreatment of coal liquefied oil by a gas-phase hydrotreatment device are supplied to a coal slurry making vessel which are mixed to obtain a slurry mixture. The slurry mixture is supplied to and preheated by the preheater The slurry mixture after being preheated is fed to the gas-liquid separator and separated into a gas component and a liquid component at a temperature of about 300 0 C, the gas component being cooled and supplied as light oil (recycle solvent) to the coal slurry making vessel A catalyst (including a co-catalyst such as sulfur) and a hydrogen gas are added to the slurry mixture from which the gas component (light oil) is separated, and fed to a hydrogenation reactor where a hydrogenation product is obtained. At this time, as the hydrogenation reactor a bubble tower type reactor is typical. The typical *'*hydrogenation reaction conditions are temperature 450 0

C,

pressure 15 MPa, and time 1 hr.

The obtained hydrogenation product is introduced into a gas-liquid separator where a gas-phase component in the conditions of high temperature an high pressure is separated.

The gas-phase component is fed to the gas-phase hydrotreatment device and subjected to hydrotreatment to obtain a hydrotreated solvent. At this time, as the gas-phase hydrotreatment device, a continuous fixed bed type reactor filled with a hydrotreatment catalyst is typically used. The -22- 11111 L :1 i'1'11 '01 typical hydrotreatment conditions are temperature 350 0

C,

pressure 15 MPa, and LHSV (Liquid Hourly Space Velocity) 1 hr- 1 The obtained hydrotreated solvent is introduced into the gas-liquid separator and separated into light oil having a boiling point of 300 0 C or less, and heavy oil having a boiling point of 300 0 C to 420 0 C. The separated heavy oil is fed as a recycle solvent to the coal slurry making vessel A liquid phase portion including a catalyst separated by the gas-liquid separator is partly recycled and supplied directly to the hydrogenation reactor and a part thereof is fed to an oil separator and separated into a residue including an oil portion and a solid portion.

The apparatus shown in Fig. 2 has no gas-liquid •separator which is different from the apparatus shown in ooFig. 1 but other constitutions are the same as the apparatus shown in Fig. i. In the case where the apparatus shown in Fig. 1 is used, in the slurry mixture preheated by the preheater a gas component (light oil) is separated by the gas-liquid separating operation in the gas-liquid separator to rise the concentration of slurry of the mixture, after which the slurry mixture is fed to the hydrogenation reactor On the other hand, in the case of using the apparatus shown in Fig. 2, the separation of the gas component (light oil) by the gas-liquid separating operation of the slurry mixture and the rising of the concentration of slurry of the slurry mixture are not carried -23- 1 i;l ,n ;rru~l:rr.,rrii~i il;ii~;r lir:ml;;;lliaall!l a ;i 1 out but the slurry mixture after being preheated by the preheater is directly fed to the hydrogenation reactor In the present invention, as coal, subbituminous coal and bituminous coal other than low carbonization degree coal such as brown coal can be used. Particularly, brown coal can be advantageously used (the sixth invention). This is because of the fact that since in brown coal, the pore structure is developed as previously mentioned, the impregnation of solvent tends to occur, and the viscosity of the slurry mixture tends to become high, whereas in the process of the present invention, the rise of viscosity of the slurry mixture caused by impregnation of solvent is hard to occur, which effect is notable. From a viewpoint of the above, among brown coal, coal belonging to brown coal of heating value: less than 7300 Kcal/Kg (anhydrous no-mineral material .i standard) defined in JIS M 1002 can be advantageously used.

The coal is dried to water content less than about 15% and then pulverized to particle size which is finer than about meshes before use. In this case, coal liquefaction can be carried out more efficiently by the process of the present invention.

"The process for separation operation of a solvent, an oil portion or a solid portion in the gas-liquid separation step and the oil separation step is not particularly limited but means such as filtration other than distillation can be employed. In case of distillation, the distillation -24conditions suitable for an object as desired can be suitably selected.

Embodiments of the present invention will be described hereinafter, but the present invention is not limited to these embodiments as long as they are beyond the subject matter thereof. Table 1 shows the kind of raw coal in the embodiments, the kind of slurry preparing solvents (the mixing rate of light oil and heavy oil, the content of oxygen), the slurry viscosity (viscosity of the slurry mixture) when the ratio (SIC ratio) of the mass of the slurry preparing solvent to the mass of coal in a moisture free and ash free state is 1.5, the S/C i:i: ratio when the slurry viscosity at 1000C is 500 mPaos (slurry viscosity of the liquid feed limit), the S/C ratio after the slurry mixture of slurry viscosity at 0 IOOC 500 mPa.s is separated with light oil by distillation operation, and the results of liquefaction reaction of the slurry mixture after separation with light oil. Table 1 further shows those of comparative examples obtained for the I:i purpose of comparison.

EMBODIMENT 1 Brown coal A (heating value: 5930 Kcal/Kg anhydrous no-mineral material standard, and a fuel ratio: 0.89) was used as raw coal, and 3 mass of pyrite was used as a catalyst. The liquefaction reaction was carried out under the conditions that temperature is 4500C and hydrogen pressure is 15 MPa under the presence of the catalyst to obtain coal liquefied crude oil. The coal liquefied crude oil was distilled (separated) to coal liquefied oil in the boiling point range from 180 0 C to 420 0 C by distillation. The hydrotreatment was carried out under the conditions that temperature is 350 0 C, hydrogen pressure is 15 MPa and LHSV is 1.0 hr 1 by a continuous fixed bed type high pressure reactor filled with a Ni-Mo catalyst using the coal liquefied oil to obtain a hydrotreated solvent. The hydrotreated solvent was distilled and separated into light oil in the boiling point range from 180 0 C to 300 0 C and heavy oil in the boiling point range from 300 0 C to 420 0 C. The light oil of the hydrotreated solvent and the heavy oil of the hydrotreated solvent were mixed in the ratio of 50 mass to 50 mass as shown in Table 1 to obtain a mixed solvent. The content of oxygen in the mixed solvent was obtained by element analysis, it was 1.25 mass as given in Table 1.

The mixed solvent was used as a slurry preparing solvent, and the dried ~and pulverized brown coal A (water content is 14.54 mass and particle size is less than 60 meshes) was used as raw coal to prepare a coal slurry. In the case where the slurry is prepared with the ratio (SIC ratio) of the mass of the mixed solvent to the mass of coal in a moisture free and ash free state being (concentration of coal in the slurry is 40 mass the slurry viscosity was measured by a double cylindrical rotary viscometer. The slurry viscosity at 100 0

C

was about 320 mPaes as shown in Table 1. The mixing ratio (S/C ratio) of the mixed solvent to the coal mass was adjusted so that the slurry viscosity at 100 0

C

is 500 mPaos slurry viscosity of the liquid feed limit). The S/C ratio was 1.25 -26- (concentration of coal in the slurry is 44.4 mass as shown in Table 1.

Light oil in the boiling point range less than 300 0 C was separated by the distillation operation using the slurry of the S/C ratio 1.25 to obtain a slurry of the S/C ratio 0.63 (concentration of coal in the slurry 61.3 mass as shown in Table 1. A pyrite catalyst in an amount of 3 mass with respect to mass of coal in dry ash was added into an autoclave (internal volume 30 cc) using 10 cc of the slurry, and the liquefaction reaction was carried out under the conditions that hydrogen pressure is 15 MPa and temperature is 450 0 C. After completion of reaction, the products are separated and divided using a solvent fractional process. The yield of oil portion (n-hexane soluble portion) was 77.1 mass as shown in Table 1. The yield of gas component was 14.2 mass and the consumption amount of hydrogen was 5.8 mass EMBODIMENT 2 In the same manner as in Embodiment 1, a hydrotreated solvent was obtained, from which light oil in the boiling point range from 180 0 C to 300 0 C and heavy oil in the boiling "point range from 300 0 C to 420 0 C were separated. The light oil and the heavy oil were mixed in the ratio of 70 mass to mass to obtain a mixed solvent. The content of oxygen of the thus obtained mixed solvent was 1.03 mass The mixed solvent was used as a slurry preparing solvent, and the dried and pulverized brown coal similar to Embodiment 1 was used as -27raw coal to prepare a coal slurry. The slurry was prepared with the S/C ratio being 1.5 and the slurry viscosity was measured. The slurry viscosity at 100 0 C was about 250 mPa-s.

The S/C ratio was adjusted so that the slurry viscosity at 100'C is 500 mPa.s. The S/C ratio was 1.10 (concentration of coal in the slurry 47.6 mass Light oil in the boiling point range less than 300 0 C was separated by the distillation operation using the slurry with the S/C ratio 1.10 to obtain a slurry with the S/C ratio 0.33 (concentration of coal in the slurry 75.1 mass The liquefaction reaction was carried out under the conditions similar to that of Example 1 using 10 cc of slurry. The yield of oil portion was 80.1 mass Further, the yield of gas component was 14.8 mass and the hydrogen consumption amount was 6.1 mass EMBODIMENT 3 In the same manner as in Embodiment 1, a hydrotreated solvent was obtained, from which light oil in the boiling point range from 180 0 C to 300 0 C and heavy oil in the boiling point range from 300 0 C to 420 0 C were separated. The light oil and the heavy oil were mixed in the ratio of 30 mass to mass to obtain a mixed solvent. The content of oxygen of the thus obtained mixed solvent was 1.47 mass The mixed solvent was used as a slurry preparing solvent, and the dried and pulverized brown coal similar to Embodiment 1 was used as raw coal to prepare a coal slurry. The slurry was prepared with the S/C ratio being 1.5 and the slurry viscosity was -28measured. The slurry viscosity at 100 0 C was about 410 mPa.s.

The S/C ratio was adjusted so that the slurry viscosity at 100°C is 500 mPa.s. The S/C ratio was 1.40 (concentration of coal in the slurry 41.6 mass Light oil in the boiling point range less than 300 0 C was separated by the distillation operation using the slurry with the S/C ratio 1.40 to obtain a slurry with the S/C ratio 0.98 (concentration of coal in the slurry 50.5 mass The liquefaction reaction was carried out under the conditions similar to that of Example 1 using 10 cc of slurry. The yield of oil portion was 73.6 mass Further, the yield of gas component was 13.1 mass and the hydrogen consumption amount was 5.6 mass EMBODIMENT 4 SBrown coal B (heating value 6640 Kcal/Kg anhydrous no-

S.

mineral material standard, and a fuel ratio 0.94) was used.

In the same manner as in Embodiment 1, a hydrotreated solvent was obtained, from which light oil in the boiling point range from 180 0 C to 300 0 C and heavy oil in the boiling point range from 300 0 C to 420°C were separated. The light oil and the heavy oil were mixed in the ratio of 50 mass to 50 mass to obtain a mixed solvent. The content of oxygen of the thus obtained mixed solvent was 0.86 mass The mixed solvent was used as a slurry preparing solvent, and the dried and pulverized brown coal B (water content is 13.90 mass and particle size is less than 60 meshes) was used as raw coal to prepare a coal slurry. The slurry was prepared with the S/C -29ratio being 1.5 and the slurry viscosity was measured. The slurry viscosity at 100 0 C was about 260 mPa-s. The S/C ratio was adjusted so that the slurry viscosity at 100 0 C is 500 mPa.s. The S/C ratio was 1.15 (concentration of coal in the slurry 46.5 mass Light oil was separated by the distillation operation using the slurry with the S/C ratio 1.15 to obtain a slurry with the S/C ratio 0.58 (concentration of coal in the slurry 63.3 mass The liquefaction reaction was carried out under the conditions similar to that of Embodiment 1 using 10 cc of slurry. The yield of oil portion was 77.9 mass Further, the yield of gas component was 14.5 mass and the hydrogen consumption amount was 5.9 mass COMPARATIVE EXAMPLE 1 e The coal liquefied crude oil was obtained in the same process as in Embodiment 1. The coal liquefied crude oil was distilled to coal liquefied oil in the boiling point range from 180°C to 420 0 C by distillation. The hydrotreatment was carried out under the conditions that temperature is 250 0

C,

*e hydrogen pressure is 15 MPa and LHSV is 1.0 hr- 1 by a continuous fixed bed type high pressure reactor filled with a Ni-Mo catalyst using the coal liquefied oil to obtain a hydrotreated solvent. The hydrotreated solvent was distilled and separated into light oil in the boiling point range from 180 0 C to 300 0 C and heavy oil in the boiling point range from 300 0 C to 420°C. The light oil of the hydrotreated solvent and the heavy oil of the hydrotreated solvent were mixed in the ratio of 50 mass to 50 mass to obtain a mixed solvent.

The content of oxygen in the obtained mixed solvent was 1.80 mass The mixed solvent was used as a slurry preparing solvent, and the dried and pulverized brown coal similar to Embodiment 1 was used as raw coal to prepare a coal slurry.

In the case where the slurry is prepared with the ratio (S/C ratio) being 1.5, the slurry viscosity was measured. The slurry viscosity at 100 0 C was 1200 mPa.s. The ratio S/C was adjusted so that the slurry viscosity at 100 0 C is 500 mPa-s.

The S/C ratio was 2.30 (concentration of coal in the slurry is 30.3 mass which is a higher value than those of Embodiments 1 to 3.

Light oil was separated using the slurry of the S/C ratio 2.30 to obtain a slurry of the S/C ratio 1.15 (concentration of coal in the slurry 46.5 mass The go liquefaction reaction was carried out using 10 cc of the slurry under the same conditions as in Embodiment 1. The yield of oil portion was 64.3 mass which is a lower value *P than those of Embodiments 1 to 3.

o* COMPARATIVE EXAMPLE 2 The hydrotreated solvent was obtained in the same process as in Embodiment i. This was separated into light oil in the boiling point range from 180 0 C to 300 0 C and heavy oil in the boiling point range from 300 0 C to 420 0 C. The light oil and the heavy oil were mixed in the ratio of 80 mass to mass to obtain a mixed solvent. The content of oxygen in -31the obtained mixed solvent was 0.92 mass The mixed solvent was used as a slurry preparing solvent, and the dried and pulverized brown coal similar to Embodiment 1 was used as raw coal to prepare a coal slurry. In the case where the slurry is prepared with the ratio (S/C ratio) being 1.5, the slurry viscosity was measured. The slurry viscosity at 100 0 C was 180 mPa.s. The ratio S/C was adjusted so that the slurry viscosity at 100 0 C is 500 mPa-s. The S/C ratio was 0.97 (concentration of coal in the slurry is 50.8 mass Light oil was separated using the slurry of the S/C ratio 0.97 to obtain a slurry of the S/C ratio 0.19 (concentration of coal in the slurry 84.0 mass The liquefaction reaction was carried out using 10 cc of the slurry under the same conditions as in Embodiment i. However, since the slurry is consistent, even if the temperature is *000° e risen up to 450 0 C, the stirring cannot be made, failing to

S

*carry out the liquefaction reaction.

S.

oCOMPARATIVE EXAMPLE 3 The hydrotreated solvent was obtained in the same process as in Embodiment i. This was separated into light oil *Goo in the boiling point range from 180 0 C to 300 0 C and heavy oil in the boiling point range from 300 0 C to 420 0 C. The light oil and the heavy oil were mixed in the ratio of 20 mass to mass to obtain a mixed solvent. The content of oxygen in the obtained mixed solvent was 1.58 mass The mixed solvent was used as a slurry preparing solvent, and the dried and pulverized brown coal similar to Embodiment 1 was used as raw -32coal to prepare a coal slurry. In the case where the slurry is prepared with the ratio (S/C ratio) being 1.5, the slurry viscosity was measured. The slurry viscosity at 100 0 C was 950 mPaos. When the slurry viscosity at 100 0 C is 500 mPa-s, the S/C ratio was 2.12 (concentration of coal in the slurry is 32.0 mass Light oil was separated by distillation operation using the slurry of the S/C ratio 2.12 to obtain a slurry of the S/C ratio 1.70 (concentration of coal in the slurry 37.0 mass The liquefaction reaction was carried out using cc of the slurry under the same conditions as in Embodiment 1. The yield of an oil portion was 63.2 mass which is lower in liquefying reactivity than those of Embodiments 1 to 3.

*3-

S.

S S -33-

B

N'Wfrl^'^itfrflA";ft"'l: Ai i

S

S S S S S S 5.

S **S j 0 S* S

S

S* S S S S S

S

55 455 S SO OS S S S OS 55 S 555; S S S S. *5 S* Mixing ratio Material preparing S/C ratio Result of liquefying of solvent step -after reaction Raw Light Heavy Oxygen Propor- Slurry S/C separation Yield Yield Hydrogen material oil oil content tion of viscosit-. ratio of of oil of gas consumpcoal wt.% wt.% of hydroxyl mPa-a light oil wt.% wt.% tion wt.

solvent group amount wt.% *1 *2 *3 *7 *7 Embodiment Brown 50.0 50.0 1.25 70 320 1.25 0.63 77.1 14.2 5.8 1 coal A Embodiment Brown 70.0 30.0 1.03 70 250 1.10 0.33 80.1 14.8 6.1 2 coal A Embodiment Brown 30.0 70.0 1.47 70 410 1.40 0.98 73.6 13.1 5.6 3 coal A Embodiment Brown 50.0 50.0 0.86 65 260 1.15 0.58 77.9 14.5 5.9 4 coal B Embodiment Brown 50.0 50.0 1.23 55 240 1.12 0.56 79.2 13.8 5.9 coal C Comparative Brown 50.0 50.0 1.80 70 1200 2.30 1.15 64.3 17.2 4.9 Example 1 coal A Comparative Brown 80.0 20.0 0.92 70 180 0.97 0.19 *8 Example 2 coal A Comparative Brown 20.0 80.0 1.58 170 950 12.12 1.70 63.2 18.3 4.8 Example 3 coal A (Note) Proportion of oxygen amount of an oxygen containing compound having oxygen as hydroxyl group with respect to the oxygen amount of the oxygen containing comp having oxygen in a mixed solvent.

In S/C ratio:1.5, slurry viscosity at 100 0

C

SIC ratio when slurry viscosity at 100 0 C is 500 mPa-s Separation of light oil from slurry in slurry viscosity at 100 0 C :500 mPa-s Supply of slurry after separation of light oil to liquefying reaction Liquefying reaction conditions: apparatus 0.3L-AC; reaction temperature 450'C; reaction time 60 min Yield of n-hexane soluble oil portion Anhydride ash-free standard Stirring is impossible because slurry is consistent in liquefying reactor a ound EMBODIMENT Brown coal C (calorific value: 6520 Kcal/Kg; anhydrous non-mineral reference; fuel ratio: 0.91) was used as raw coal, and 3 mass of pyrite was used as a catalyst. A liquefaction reaction was carried out under the conditions that temperature is 450'C and hydrogen pressure is 15 MPa in the presence of the catalyst to obtain a coal liquefied crude oil. The coal liquefied crude oil was cut into a coal liquefied oil at a boiling point in the range from 180 0 C to 420 0 C by distillation. This coal liquefied oil was used, and a hydrogenation process was carried out under the conditions that temperature is 350 0 C, hydrogen pressure is MPa, LHSV is 1.0 hr-i using a continuous fixed bet type high pressure reaction device filled with a Ni-Mo catalyst to obtain a hydrogenated solvent. The hydrogenated solvent 555.

was separated by the distillation into light oil at a boiling point in the range from 180 0 C to 300 0 C and heavy oil at a boiling point in the range from 300 0 C to 420 0

C.

The light oil of the hydrogenated solvent and the heavy oil of the hydrogenated solvent were mixed in a proportion of 50 mass to 50 mass to obtain a mixed solvent. The oxygen content of the obtained mixed solvent was obtained by an element analysis, it was 1.23 mass as shown in Table 1. The proportion of the oxygen containing compound having oxygen as a hydroxyl group with respect to the amount of the oxygen containing compound having oxygen contained in the solvent was 55 mass in the proportion of the oxygen amount.

The mixed solvent was used as a slurry preparing solvent and the dried and pulverized brown coal C (moisture: 13.5 mass grain size: less than mesh) was used as raw coal to prepare a coal slurry. In the case where the slurry was prepared in the ratio (SIC ratio) between a mass of mixed solvent and a mass of coal in a moisture free and ash free state of 1.5 (coal concentration in the coal slurry 40 mass the slurry viscosity was measured using a double cylindrical type rotational viscometer, the slurry viscosity at IOO°C was approximately 240 mPaos as shown in Table 1.

Further, the mixing ratio (S/C ratio) between the mixed solvent and the coal "was regulated so that the slurry viscosity at IOO°C is 500 mPaos. Then the S/C ratio was 1.12 (coal concentration in the coal slurry: 44.4 mass .Q The coal slurry at the S/C ratio of 1.12 was used and light oil at a boiling point of 300°C or less was separated by distillation operation to Il:i obtain a coal slurry at the SIC ratio of 0.56 (coal concentration in the slurry 64.1 mass A pyrite catalyst in 3 mass with respect to coal mass in a moisture free and ash free state was added into an autoclave (internal volume: 30 cc) using 10 cc of the slurry, and a liquefaction :Cos.: reaction was carried out under the conditions that hydrogen pressure is MPa and temperature is 450 0 C. After completion of the reaction, the product was separated and divided using a solvent discrimination method. The yield of an oil portion (n-hexane soluble portion) was 79.2 mass% as shown in Table 1. The yield of a gas component was -36- 13.8 mass and a hydrogen consumption amount was 5.9 mass Where the terms "comprise", "comprises", "comprised" or "comprising" are used in this specification, they are to be interpreted as specifying the presence of the stated features, integers, steps or components referred to, but not to preclude the presence or addition of one or more other feature, integer, step, component or group thereof.

e.

*0 9 -37-

Claims (7)

1. A process for coal liquefaction including: a raw material preparation step in which a solvent is mixed with raw coal to obtain a slurry mixture; and, (ii) a hydrogenating step for adding hydrogen to said mixture to hydrogenate the coal; characterized by using as the solvent a mixed solvent having less than mass of oxygen; said mixed solvent comprising a mixture of a light oil 10 and a heavy oil obtained by subjecting coal liquefied oil to hydrotreatment. SOO**

2. A process for coal liquefaction as defined in claim 1, wherein the slurry mixture obtained in the raw material preparation step is preheated, and the ~light oil in the mixed solvent in the slurry mixture is removed by a gas- 15 liquid separating operation to increase the concentration of the slurry ore* mixture, which is then fed to said hydrogenating step. *o 0too*

3. A process for coal liquefaction as defined in claim 2, wherein the mass of solvent in the slurry mixture fed to said hydrogenating step is 0.3 to times the mass of raw coal in a moisture-free and ash-free state.

4. The process for coal liquefaction as defined claim 2 or claim 3, wherein the amount of light oil in the mixed solvent is 30 to 70 mass -38- ck9522augl claims A process for coal liquefaction as defined in any one of claims 1 to 4, wherein the mass of solvent mixed with the raw coal is 1.0 to 1.5 times the mass of raw coal in a moisture-free and ash-free state.

6. A process for coal liquefaction as defined in any one of claims 1 to wherein said raw coal is brown coal.

7. A process for coal liquefaction as defined in any one of claims 1 to 6, wherein said light oil has a continuous boiling point distribution of less than 300 0 C, and said heavy oil has a continuous boiling point distribution from 3000C to 4200C.

8. A process for coal liquefaction as defined in any one of claims 1 to 7, 000 **0o wherein the amount of oxygen contained in oxygen-containing compounds 15 having oxygen as a hydroxyl group with respect to the amount of oxygen 000 0•• contained in oxygen-containing compounds in the said mixed solvent is *0 0000 less than 60 mass DATED this z day of/' 200L, KOBE STEEL LTD MITSUBISHI CHEMICAL CORPORATION IDEMITSU KOSAN CO. LTD COSMO OIL COMPANY LTD NISSHO IWAI CORPORATION By their Patent Attorneys: CALLINAN LAWRIE