CN109355100B

CN109355100B - Coal tar processing and coal co-refining combined process

Info

Publication number: CN109355100B
Application number: CN201811543935.9A
Authority: CN
Inventors: 韩磊; 李大鹏; 王明峰; 霍鹏举; 高亚男; 王永娟; 黄传峰; 程秋香; 杨天华; 刘树伟; 王焜
Original assignee: Shaanxi Yanchang Petroleum Group Co Ltd
Current assignee: Shaanxi Yanchang Petroleum Group Co Ltd
Priority date: 2018-12-17
Filing date: 2018-12-17
Publication date: 2021-03-16
Anticipated expiration: 2038-12-17
Also published as: CN109355100A

Abstract

A coal tar processing and coal are combined together and refined, said process carries on the phenol extraction treatment to the light component of coal tar at first; then, pre-hydrogenation is carried out on the coal tar heavy distillate oil, the conversion of colloid and asphaltene in the heavy distillate oil into partially hydrogenated polycyclic aromatic hydrocarbon is promoted, and the hydrogen supply performance of the heavy distillate oil is improved; and finally, mixing the liquid phase products with different distillation ranges in the hydrogenated separator with the coal powder, and feeding the mixture into a kerosene co-refining device to finally obtain gasoline, diesel oil and phenol products, thereby realizing the co-treatment of coal tar and coal. The method combines the processes of coal tar phenol extraction, heavy fraction pre-hydrogenation and kerosene co-refining, not only realizes the quality-divided utilization of coal tar, but also provides a large amount of solvent oil with good hydrogen supply performance for the kerosene co-refining, greatly improves the conversion efficiency of the coal tar and coal, and has the advantages of low hydrogen consumption, high oil yield, good economic benefit, long-period and large-scale operation of the kerosene co-refining device and the like.

Description

Coal tar processing and coal co-refining combined process

Technical Field

The invention belongs to the technical field of chemical industry, and particularly relates to a combined process of coal tar processing and coal co-refining.

Background

The coal liquefaction technology is an advanced coal cleaning technology for converting coal into liquid fuel, chemical raw materials and products through deep hydrocracking reaction under the action of hydrogen and a catalyst. China is a large country for producing coal and consuming fuel oil, and the external dependence of crude oil is close to 60 percent, so that the development of the coal hydrogenation liquefaction technology is one of important methods for realizing clean and efficient utilization of coal resources, ensuring the safety of energy and environment in China and relieving the current situation of environmental pollution in China.

The Shenhua group develops a direct coal liquefaction (CDCL) technology (Chinese patent 1587351) with the independent property rights of China, and realizes the production scale of millions of tons. The technology takes Shenhua coal as a liquefaction raw material, adopts a two-section series suspension bed hydrocracking reactor with a forced circulation pump, and is matched with a circulating hydrogenation solvent and an iron-based high-efficiency catalyst to realize the coal liquefaction reaction. According to the technology, most of liquefied products are returned to the device as the solvent oil in the process of direct coal liquefaction, so that the processing capacity of the direct coal liquefaction device is greatly reduced, and the problems of too light solvent oil, poor slurrification, insufficient hydrogen supply capacity and the like caused by repeated cyclic cracking reaction of the solvent oil are solved.

The coal tar is a liquid product obtained in the high-temperature dry distillation process of coal, compared with petroleum-based distillate oil, the coal tar maintains the characteristics of partial chemical composition of the coal, has the characteristics of high heteroatom content, high ash content, high polycyclic aromatic hydrocarbon content, high colloid content, high asphaltene content and the like, and has the problems of coking and deposition of a reaction system, service life of a catalyst and the like when the conventional petroleum hydrotreating catalyst and process are adopted. According to the principle of similarity and intermiscibility, polycyclic aromatic hydrocarbons with a solvent structure similar to that of coal molecules have strong dissolving capacity on free radical fragments generated by coal pyrolysis, so that coal tar serving as solvent oil reacts with coal, and the method is an important way for realizing co-processing of the coal tar and the coal. Patent CN104419437A discloses a direct coal liquefaction process mixed with high-temperature coal tar, which comprises the steps of purifying the high-temperature coal tar, distilling the purified high-temperature coal tar under reduced pressure or normal pressure, and cutting into light oil fraction at the temperature of less than 350 ℃ and heavy oil fraction at the temperature of more than 350 ℃; coal oil slurry mixed by coal powder and heavy oil fraction at the temperature of more than 350 ℃, hydrogen and a catalyst react in a first-stage reactor, a first-stage reaction product is fed into the upper part of a second-stage reactor, gas-phase components in the first-stage reaction product flow out from the top of the second-stage reactor, solid-liquid components flow downwards in the second-stage reactor and are in countercurrent contact reaction with the hydrogen flowing upwards, and fractionation is carried out after the reaction is finished.

A large number of researches show that the partially hydrogenated polycyclic aromatic hydrocarbon (such as tetrahydronaphthalene, dihydrophenanthrene, dihydroanthracene, tetrahydroanthracene and the like) is good hydrogen supply solvent oil for coal hydrogenation liquefaction. The patent CN104194830A discloses a coal direct liquefaction circulating solvent, a processing method thereof and a coal direct liquefaction method using the same, and the method provides the coal direct liquefaction circulating solvent with better hydrogen supply performance for the coal direct liquefaction reaction through the steps of cutting and fractionating the circulating solvent, hydrogenating heavy fractions and the like. The untreated full-range coal tar is low in partially hydrogenated polycyclic aromatic hydrocarbon content and poor in hydrogen supply capacity, and contains a large amount of colloid asphaltenes, so that coal and coal tar are directly subjected to liquefaction reaction according to patent CN104419437A, and although co-treatment of the coal and the coal tar can be realized, the problems of low conversion rate, easy coking of reactants and the like are encountered in the process of treating the coal tar with high colloid and asphaltene content, meanwhile, the coal tar contains higher oxygen compounds, wherein the content of phenol and derivatives thereof can reach 8% -30%, the phenol has higher economic value, the hydrogen consumption in the reaction process is increased by directly carrying out hydrogenation reaction on the phenol, and the economic benefit is lower.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a combined process of coal tar processing and coal co-refining, which not only can provide a large amount of solvent oil with good hydrogen supply performance for the coal hydrogenation liquefaction reaction, but also can realize the quality-based utilization of the coal tar and greatly improve the production efficiency of a kerosene co-refining device.

In order to achieve the purpose, the invention adopts the technical scheme that:

a coal tar processing and coal co-refining combined process comprises the following steps;

a) the coal tar 13 enters a distillation device 1 for separation, the separated light components enter a tar phenol extraction device 3 to obtain crude phenol 15 and raffinate oil 16, and the separated heavy components, a heavy oil hydrogenation catalyst 14 and circulating oil slurry 31 enter a mixing tank 2, are fully stirred and then enter a pre-hydrogenation reaction device 4 together with hydrogen 17;

b) gas-liquid products after reaction in the pre-hydrogenation reaction device 4 sequentially enter a thermal high-pressure separator 5, a medium-temperature high-pressure separator 6 and a low-temperature high-pressure separator 7 to respectively obtain high-temperature solvent oil 18, low-temperature solvent oil 19 and light oil 28;

c) the low-temperature solvent oil separated by the medium-temperature high-pressure separator 6 is subjected to temperature and pressure reduction, then mixed with the coal powder 20 and the direct coal liquefaction catalyst 21 in the oil-coal mixing tank 8, subjected to temperature and pressure rise, mixed with the high-temperature solvent oil 18 separated by the high-temperature high-pressure separator 5 to obtain oil-coal slurry, mixed with hydrogen 22, and then fed into the kerosene co-refining device 9;

d) sending the product of the kerosene co-refining device 9 into a gas-liquid separation device 10 to obtain light component oil and heavy component oil, sending the heavy component oil into a reduced pressure distillation device 12 to obtain tower top oil 29, residue 30 and circulating oil slurry 31 extracted from a side line, circularly returning the circulating oil slurry 31 to the mixing tank in the step a), and discharging the residue 30 out of the reduced pressure distillation device 12;

e) mixing the overhead oil 29 separated by the vacuum distillation device 12 with the raffinate oil separated by the tar phenol extraction device 3 in the step a), the light oil 28 separated by the low-temperature high-pressure separator 7 in the step b), the light component oil separated by the gas-liquid separation device 10 in the step e) and hydrogen 23, and then feeding the mixture into the fixed bed hydrogenation device 11 to obtain LPG24, a gasoline component 25, a diesel oil component 26 and circulating wax oil 27, wherein the circulating wax oil 27 returns to the fixed bed hydrogenation device 11.

The coal tar 13 of the step a) is one or a mixture of more than one of low-temperature coal tar, medium-low-temperature coal tar and high-temperature coal tar in any proportion, wherein the coal tar is subjected to dehydration and mechanical impurity removal pretreatment, the water content is not higher than 2%, the mechanical impurities are not higher than 1%, and the total content of colloid and asphaltene is higher than 80%.

The pre-hydrogenation reaction device 4 adopts one or more structures connected in series, the pre-hydrogenation reaction device 4 is one or more structures connected in series in a bubbling bed reactor, a suspension bed reactor and a boiling bed reactor, and the operating pressure of the pre-hydrogenation reaction device is 10-18 MPa, the temperature is 380-465 ℃, the volume ratio of hydrogen to oil is 500-2000, and the airspeed is 0.8-2.5 h^-1。

The top temperature of the hot high-pressure separator 5 in the step b) is 300-440 ℃, the pressure is 10-18 MPa, and the initial boiling point of the high-temperature solvent oil is more than or equal to 280 ℃.

The top temperature of the medium-temperature high-pressure separator 6 in the step b) is 200-350 ℃, the pressure is 10-18 MPa, and the distillation range of the low-temperature solvent oil is 200-460 ℃.

The mass content of coal dust in the oil coal slurry in the step c) is 35-55%, the coal dust is one or a mixture of sub-bituminous coal and lignite, and the mass content of the kerosene co-refining catalyst is 0.5-4%.

The kerosene co-refining device 9 adopts one or more suspension bed reactors connected in series, the operation pressure of the suspension bed reactor is 18-23 MPa, the temperature is 440-500 ℃, the gas-liquid ratio is 500-1500L/kg, and the airspeed is 0.2-1.5 h^-1。

The fixed bed hydrogenation device 11 adopts one or more fixed bed reactors connected in series, a hydrofining catalyst bed layer, a hydro-upgrading catalyst bed layer and a hydrocracking catalyst bed layer are arranged in the reactors, the operating pressure of the fixed bed reaction device is 8-18 MPa, the temperature is 320-420 ℃, the volume ratio of hydrogen to oil is 600-2400, and the space velocity is 0.5-2.0 h^-1。

When the fixed bed hydrogenation device 11 is two fixed bed reactors connected in series, raffinate oil and light oil enter a bed layer of a second fixed bed reactor.

The invention has the beneficial effects that:

(1) the method combines the coal tar phenol extraction process and the kerosene co-refining process, not only realizes the quality-based utilization of the coal tar, but also provides a large amount of solvent oil for the kerosene co-refining, greatly improves the production efficiency of the kerosene co-refining device, reduces the hydrogen consumption and the corrosion to equipment in the coal tar processing process, obtains phenols with high added value, and increases the economic benefit of the process.

(2) The method of the invention performs mild pre-hydrogenation reaction on the heavy-distillate coal tar, promotes the hydrogenation of asphaltene and colloid components in the coal tar to be converted into partially hydrogenated polycyclic aromatic hydrocarbon, so that the coal tar becomes kerosene co-refining solvent oil with good hydrogen supply performance, the conversion efficiency of the coal tar and coal is improved, and the adaptability of the device to the high-asphaltene and high-colloid coal tar is enhanced.

(3) After the heavy fraction coal tar is subjected to pre-hydrogenation, the hydrogenation product is separated in a multi-stage separation mode, high-temperature solvent oil obtained by a thermal high-pressure separator is directly sent to a kerosene co-refining reactor according to the temperature, pressure and composition characteristics of products of different separators, so that the energy consumption of the reaction is reduced, and low-temperature solvent oil obtained by a medium-temperature high-pressure separator is mixed with coal, thereby being beneficial to slurrying, dissolving and conveying of coal dust.

(4) When the pre-hydrogenation reaction device adopts a bubbling bed reactor and a suspension bed reactor, the heavy oil hydrogenation catalyst and high-temperature solvent oil enter the kerosene co-refining reaction device after the pre-hydrogenation reaction, so that the coal hydrogenation liquefaction performance is improved.

(5) The method of the invention returns the distillate oil extracted from the side line of the vacuum tower as the circulating solvent oil for hydrogenation reaction, provides the hydrogenation reaction raw material with high hydrogen-carbon ratio and low heteroatom content for the fixed bed hydrogenation device, and prevents the fixed bed catalyst from coking, poisoning and inactivation.

(6) When the fixed bed hydrogenation device is a plurality of fixed bed reactors, the light distillate oil selectively enters the fixed bed reactors, so that the cracking of the light distillate oil is reduced, and the yield of oil products is improved.

(7) The method has the advantages of high conversion rate of coal and coal tar, high liquid yield, low hydrogen consumption and the like, and is easy to realize long-period and large-scale operation of the kerosene co-refining device.

Drawings

FIG. 1 is a schematic process flow diagram of the process of the present invention.

FIG. 2 is a graph showing the boiling range distribution of two coal tars in an example of the present invention.

Wherein, 1-a distillation device; 2-mixing tank; 3-a tar phenol extraction device; 4-a pre-hydrogenation reaction device; 5-a hot high pressure separator; 6-medium temperature high pressure separator; 7-a low temperature high pressure separator; 8-oil-coal mixing tank; 9-a kerosene co-refining unit; 10-a gas-liquid separation device; 11-fixed bed hydrogenation unit; 12-a reduced pressure distillation unit; 13-coal tar; 14-heavy oil hydrogenation catalyst; 15-crude phenol; 16-raffinate oil; 17-hydrogen; 18-high temperature mineral spirits; 19-low temperature mineral spirits; 20-coal; 21-kerosene co-refining catalyst; 22-hydrogen; 23-hydrogen; 24-LPG; 25-a gasoline component; 26-a diesel component; 27-circulating wax oil; 28-light oil; 29-vacuum tower top oil; 30-residue; 31-circulating oil slurry; 32-light component oil.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

The two kinds of coal tar adopted in the embodiment of the invention are representative medium and low temperature coal tar in the elm area, the coal powder is the coal of the west gulf of the elm area, and the hydrogen source is obtained by a mode of producing hydrogen by coal. The raw material properties, test conditions, test results and product distribution are shown in the figure and table.

Example 1

Referring to fig. 1 and fig. 2, coal tar 13 is sent to a distillation device 1 for separation, the separated light components enter a tar phenol extraction device 3 to obtain crude phenol 15 and raffinate oil 16, and the heavy components, a heavy oil hydrogenation catalyst 14 and circulating slurry oil 31 enter a mixing tank 2, are fully stirred and then enter a pre-hydrogenation reaction device 4 together with hydrogen 17; the pre-hydrogenation reaction device 4 comprises 3 bubbling bed reactors connected in series in sequence, the operating pressure is 16MPa, the temperature is 447 ℃, the volume ratio of hydrogen to oil is 1600, and the space velocity is 1.42h^-1(ii) a Gas-liquid products of the pre-hydrogenation reaction device 4 sequentially enter a hot high-pressure separator 5, a medium-temperature high-pressure separator 6 and a low-temperature high-pressure separator 7 to obtain high-temperature solvent oil 18, low-temperature solvent oil 19 and light oil 28, and the high-temperature solvent oil 18 directly enters a kerosene co-refining device 9; the temperature at the top of the hot high-pressure separator is 384 ℃, and the pressure is 16 Mpa; the top temperature of the medium-temperature high-pressure separator is 223 ℃, and the pressure is 16 Mpa; the low-temperature solvent oil 19 enters the oil-coal mixing tank 8 for degassing after being cooled and depressurized, and then enters the coal-oil mixing tank together with the coal powder 20 and the coal liquefaction catalyst 21, the oil-coal mixture is mixed with the high-temperature solvent oil after being heated and pressurized to obtain oil-coal slurry, the oil-coal slurry and the hydrogen gas 22 enter the kerosene co-refining device 9, the mass proportion of the coal powder in the oil-coal slurry is 46 percent, the kerosene co-refining catalyst 21 is a supported iron catalyst, and the addition amount is 1 percent (Fe/dry base coal); the kerosene co-refining device 9 comprises 2 suspended bed reactionsThe operation pressure of the reactor and the suspension bed reactor is 19MPa, the temperature is 456 ℃, the gas-liquid ratio is 1000L/kg, and the space velocity is 0.68h^-1. The product of the kerosene co-refining device 9 passes through a gas-liquid separation device 10 to obtain light component oil and heavy component oil, the heavy component oil enters a reduced pressure distillation device 12 to obtain tower top oil 29, residue 30 and circulating oil slurry 31 extracted from the side line, the circulating oil slurry 31 returns to the mixing tank 2, and the residue 30 is discharged out of the device; mixing the tower top oil 29, raffinate oil 15, light oil 28, light component oil 32 and hydrogen 23, and then entering a fixed bed hydrogenation device 11 to obtain LPG24, a gasoline component 25, a diesel oil component 26 and circulating wax oil 27, wherein the circulating wax oil 27 returns to the fixed bed hydrogenation device 11; the fixed bed hydrogenation device 11 comprises two fixed bed reactors, the temperature of the first reactor is 380 ℃, the pressure is 16Mpa, the volume ratio of hydrogen to oil is 1400, and the space velocity is 0.6h^-1The pressure of the second reactor is 16MPa, the temperature is 365 ℃, the volume ratio of hydrogen to oil is 1400, and the space velocity is 0.6h^-1(ii) a Raffinate oil 15 and light oil 28 enter the bed at the inlet of the second reactor.

Example 2

Example 2 the same procedure as in example 1 was followed, except that the operating pressure of the bubbling bed reactor in the prehydrogenation apparatus was 16MPa, the temperature was 450 ℃, the hydrogen-oil volume ratio was 1600, and the space velocity was 1.54h^-1Meanwhile, medium-low temperature coal tar 2 with high content of colloid and asphaltene is used as a raw material, and the concentration of the coal oil slurry entering a kerosene co-refining reaction device is 43 percent.

TABLE 1 Low temperature coal tar Properties

TABLE 2 Dry basis coal dust Properties

Item	Unit of	Washed coal in west bay
			Industrial analysis
Ash content	wt％	8.40
			Volatile component	wt％	34.02
Elemental analysis
			Carbon content	wt％	75.06
Hydrogen content	wt％	4.38
			Sulfur content	wt％	0.54
Nitrogen content	wt％	0.94
			Oxygen content	wt％	10.36
H/C atomic ratio	-	0.70
			Coal petrography analysis
Vitrinite group	wt％	63.2
			Inert substance group	wt％	32.6
Chitin group	wt％	1.6

Table 3 test material balance table

The water contained in the coal tar and the coal dust shown in the experimental material balance table 3 is deducted from the water product generated by the balance calculation, and the materials such as the solid load type iron catalyst, the vulcanizing agent and the like used by the kerosene co-refining reaction device are deducted from the residue and the hydrogen sulfide product in the material balance calculation process and are not listed in the balance table. Although the method of the present invention has been described above with reference to specific embodiments, a person skilled in the art may modify and change the above embodiments according to the needs of a specific application without departing from the scope of the inventive concept.

Tables 1 and 2 show properties of the combined coal tar processing and coal co-refining process feedstock, with table 1 listing two different types of coal tar feedstock. The coal tar 1 contains higher saturated components, aromatic components and asphaltene, and the hydrogen-carbon ratio is relatively low; the colloid content in the coal tar 2 is high and reaches 77.35 percent, and the hydrogen-carbon ratio is high; and the oxygen content in the two coal tar oils is basically the same and is about 6.3 percent; the raw material coal is selected from the washed coal of the West gulf, the ash content is 8.4 percent, the volatile content reaches 63.2 percent, and the method is suitable for the hydrogenation liquefaction reaction process of the coal. FIG. 2 is a distillation range distribution curve of two kinds of coal tar, and it can be seen from the graph that the distillation ranges of the two kinds of coal tar are between 100 ℃ and 600 ℃, the 50% distillation temperature is between 360 ℃ and 390 ℃, which belongs to the range of low temperature coal tar, and the distillation fraction of the coal tar 1 is slightly heavy.

Table 3 shows the results of the combined process of processing coal tar and co-refining coal in the taiwan coal by using two kinds of coal tar, respectively, and calculated by using coal dust as 100% standard feed, the conversion rate of coal tar 1 can reach 98.82%, the conversion rate of co-refining coal can reach 92.57%, the yield of crude phenol is 7.3%, the total liquid phase yield can reach 174.43%, which is equivalent to 74.36% of feed (coal tar + coal), the hydrogen consumption is only 6.33%, which is equivalent to 2.69% of feed (coal tar + coal); the conversion rate of coal tar 2 reaches 97.46%, the conversion rate of co-coking coal is 91.83%, the yield of crude phenol is 15.71%, the total liquid phase yield reaches 209.35%, which is equivalent to 80.08% of the feed (coal tar and coal), the hydrogen consumption is only 6.93%, which is equivalent to 2.65% of the feed (coal tar and coal); the coal tar processing and coal co-refining combined process realizes the quality-based utilization of the coal tar, provides a large amount of solvent oil for the co-refining of the kerosene, greatly improves the production efficiency of the coal tar co-refining device, obtains phenols with high additional values, increases the economic benefit of the process, realizes the advantages of high conversion rate of the coal and the coal tar, high liquid yield, low hydrogen consumption and the like, and is easy to realize the long-period and large-scale operation of the coal tar co-refining device.

Claims

1. A coal tar processing and coal co-refining combined process is characterized by comprising the following steps;

a) the coal tar (13) enters a distillation device (1) for separation, the separated light components enter a tar phenol extraction device (3) to obtain crude phenol (15) and raffinate oil (16), and the separated heavy components, a heavy oil hydrogenation catalyst (14) and circulating oil slurry (31) enter a mixing tank (2) and are fully stirred and then enter a pre-hydrogenation reaction device (4) together with hydrogen;

b) gas-liquid products after reaction in the pre-hydrogenation reaction device (4) sequentially enter a hot high-pressure separator (5), a medium-temperature high-pressure separator (6) and a low-temperature high-pressure separator (7) to respectively obtain high-temperature solvent oil (18), low-temperature solvent oil (19) and light oil (28);

c) the low-temperature solvent oil separated by the medium-temperature high-pressure separator (6) is cooled and depressurized, then enters an oil-coal mixing tank (8) together with coal powder (20) and a direct coal liquefaction catalyst (21) to be mixed, is heated and pressurized, and then is mixed with the high-temperature solvent oil (18) separated by the high-temperature high-pressure separator (5) to obtain oil-coal slurry, and the oil-coal slurry is mixed with hydrogen and then enters a kerosene co-refining device (9);

d) sending the product of the kerosene co-refining device (9) into a gas-liquid separation device (10) to obtain light component oil and heavy component oil, sending the heavy component oil into a reduced pressure distillation device (12) to obtain tower top oil (29), residue (30) and circulating oil slurry (31) extracted from the side line, circularly returning the circulating oil slurry (31) to the mixing tank in the step a), and discharging the residue (30) out of the reduced pressure distillation device (12);

e) mixing the tower top oil (29) separated by the vacuum distillation device (12) with the raffinate oil separated by the tar phenol extraction device (3) in the step a), the light oil (28) separated by the low-temperature high-pressure separator (7) in the step b), and the light oil and hydrogen separated by the gas-liquid separation device (10) in the step d, and then feeding the mixture into a fixed bed hydrogenation device (11) to obtain LPG (24), a gasoline component (25), a diesel oil component (26) and circulating wax oil (27), and returning the circulating wax oil (27) to the fixed bed hydrogenation device (11);

the pre-hydrogenation reaction device (4) adopts one or more structures connected in series, the pre-hydrogenation reaction device (4) is one or more structures connected in series in a bubbling bed reactor, a suspension bed reactor and a fluidized bed reactor, the operating pressure is 10-18 MPa, the temperature is 380-465 ℃, the volume ratio of hydrogen to oil is 500-2000, and the space velocity is 0.8-2.5 h^-1；

The fixed bed hydrogenation device (11) adopts one or more fixed bed reactors connected in series, a hydrofining catalyst bed layer, a hydrogenation modification catalyst bed layer and a hydrocracking catalyst bed layer are arranged in the reactors, the operating pressure of the fixed bed reaction device is 8-18 MPa, the temperature is 320-420 ℃, the volume ratio of hydrogen to oil is 600-2400, and the space velocity is 0.5-2.0 h^-1。

2. The coal tar processing and coal co-refining combined process according to claim 1, characterized in that the coal tar (13) of the step a) is one or a mixture of more than one of low temperature coal tar, medium and low temperature coal tar, high temperature coal tar in any proportion, wherein the water content of the coal tar is not higher than 2%, the mechanical impurities of the coal tar are not higher than 1%, and the total content of colloid and asphaltene of the coal tar is higher than 80%.

3. The combined process of coal tar processing and coal co-refining as claimed in claim 1, wherein the temperature at the top of the hot high-pressure separator (5) in step b) is 300-440 ℃, the pressure is 10-18 MPa, and the initial boiling point of the high-temperature solvent oil is more than or equal to 280 ℃.

4. The combined process of coal tar processing and coal co-refining as claimed in claim 1, wherein the temperature at the top of the medium temperature and high pressure separator (6) in step b) is 200-350 ℃, the pressure is 10-18 MPa, and the distillation range of the low temperature solvent oil is 200-460 ℃.

5. The coal tar processing and coal co-refining combined process according to claim 1, characterized in that the mass content of coal dust in the oil coal slurry of step c) is 35-55%, the coal dust is one or a mixture of subbituminous coal and lignite, and the mass content of the kerosene co-refining catalyst is 0.5-4%.

6. The coal tar processing and coal co-refining combined process as claimed in claim 1, wherein the kerosene co-refining device (9) adopts one or more suspension bed reactors connected in series, the operation pressure of the suspension bed reactor is 18-23 MPa, the temperature is 440-500 ℃, the gas-liquid ratio is 500-1500L/kg, and the airspeed is 0.2-1.5 h^-1。

7. The coal tar processing and coal co-refining combined process as claimed in claim 1, characterized in that the fixed bed hydrogenation unit (11) is two fixed bed reactors connected in series, and when raffinate oil and light oil enter a second fixed bed reactor bed.