CN108456546B

CN108456546B - Method for producing light oil by coal and biomass liquefaction

Info

Publication number: CN108456546B
Application number: CN201711431414.XA
Authority: CN
Inventors: 林科; 李林; 郭立新
Original assignee: Beijing SJ Environmental Protection and New Material Co Ltd
Current assignee: Beijing Haixin Energy Technology Co ltd
Priority date: 2017-12-26
Filing date: 2017-12-26
Publication date: 2020-04-10
Anticipated expiration: 2037-12-26
Also published as: CN108456546A

Abstract

The invention relates to the technical field of clean energy, in particular to a co-refining process of coal and biomass. The invention provides a method for producing light oil by coal and biomass liquefaction. The biomass coal water slurry which has high solid content and can be stably conveyed by a pump is successfully obtained by firstly carrying out compression, crushing and re-crushing on the coal and biomass raw materials and then preparing slurry. According to the invention, through two liquefaction reactions, the coal and the biomass can be fully liquefied into a liquid phase, and the liquid oil yield is improved. The yield of light oil, in particular the yield of low-boiling range oil such as naphtha in the light oil is further improved through the subsequent separation and hydrogenation steps; and reduces the residue content in the subsequent light oil.

Description

Method for producing light oil by coal and biomass liquefaction

Technical Field

The invention relates to the technical field of clean energy, in particular to a co-refining process of coal and biomass.

Background

At present, coal is used as a main energy source in China, the traditional coal utilization mode is combustion, but the problem of air pollution caused by coal combustion is increasingly serious; moreover, the coal quality of China is lowered year by year, so that the raw coal washing proportion is improved year by year, and the coal washing wastewater brings serious water pollution. The severe environmental problems have made the adjustment of energy structures one of the important tasks in energy development in our country. However, the storage condition of energy resources of China is poor oil and rich coal, a large amount of oil imports are needed to meet the production development requirement every year, if the energy structure of China is adjusted by reducing the utilization of coal resources, the energy resources with rich reserves are left, the importation amount of oil is also greatly increased, and the energy safety of China is certainly influenced.

The energy structure adjustment mode more suitable for the national conditions of China is to realize the clean and efficient utilization of coal resources. Among them, coal liquefaction technology is included. The kerosene co-refining technology is a coal liquefaction technology which is developed recently, and becomes a research hotspot for clean utilization of coal. For example, chinese patent document CN102191072 discloses a coal liquefaction technology for kerosene co-refining, which first prepares coal particles and oil into a suspension, makes the suspension pass through two serially connected boiling beds with catalyst and hydrogen added to perform liquefaction reaction, and then sends the obtained lighter components into a fixed bed reactor for further hydrogenation reaction to finally obtain naphtha, kerosene and/or diesel oil, and heavy components. The reaction conditions in the two boiling beds are 325-420 ℃, 16-20 MPa, 350-450 ℃ and 16-20 MPa in sequence, and the temperature of the second boiling bed is always higher than that of the first boiling bed by more than 10 ℃; the reaction conditions of the fixed bed reactor are 250-480 ℃ and 2-25 MPa.

However, this technology has the following problems in common with most kerosene mixing processes in the prior art:

1. limited efficiency of liquefaction

The kerosene slurry prepared from coal powder and oil is required to be conveyed into a cracking hydrogenation device by a pump, in order to ensure the stable operation and conveying of the pump, the viscosity of the kerosene slurry cannot be too high, and heavy oil, residual oil and the like which are used as dispersing agents in the kerosene slurry are all viscous liquids, so that the coal powder in the kerosene slurry cannot be too high in the kerosene co-refining technology, the concentration of reaction materials is limited, and the liquefaction efficiency is low.

2. Large hydrogen consumption

The mechanism of coal hydrocracking is as follows:

in the first stage, coal is pyrolyzed to form pre-asphaltene and asphaltene, and gas, liquefied oil and macromolecular polycondensate are generated.

In the second stage, under the condition of rich hydrogen, partial pre-asphaltene is hydrogenated to generate liquefied oil, and partial macromolecular polycondensate is hydrogenated and cracked again to generate liquefied oil with low molecular weight.

When the temperature is too high or the hydrogen supply is insufficient, the pre-asphaltenes and some of the insoluble organics in the asphaltenes can form char or semi-coke. The high concentration and high partial pressure of hydrogen are favorable for forward hydrocracking reaction of coal and reducing coke formation. The kerosene co-refining technology tends to consume a high amount of hydrogen.

In order to improve the liquefaction efficiency, researchers have been working on increasing the content of pulverized coal in kerosene slurry, for example, trying to reduce the particle size of pulverized coal as much as possible in order to increase the proportion of pulverized coal by increasing the dispersibility of pulverized coal in kerosene slurry. However, the pulverized coal has a large amount of pore structure, and the operation of reducing the particle size of the pulverized coal exposes the minute pores further, thereby adsorbing a large amount of water. As a result, the viscosity of kerosene slurry prepared from pulverized coal of smaller particle size is higher than that of kerosene slurry prepared from pulverized coal of larger particle size at the same pulverized coal weight ratio, and smooth transportation of the pump cannot be achieved at all.

Researchers have also tried to liquefy coal by using water instead of oil as a hydrogen supply solvent, and a technical paper "direct hydrogenation liquefaction performance of lignite under water or tetralin medium" discloses a technical scheme for performing hydrogenation liquefaction of lignite by using water as a medium, wherein the technical scheme is that the hydrogenation liquefaction reaction of lignite is performed in an autoclave at 380 ℃, when FeS is used as a catalyst and hydrogen is used as an atmosphere, the total conversion rate of lignite is only 40.6%, and the oil gas yield and the asphaltene yield are 39.2% and 1.4% respectively. This is because of hydrogen supply and dissolved H of water itself₂The conversion rate of lignite is low because the capacity of lignite is weak and the requirement of pyrolysis and hydrogenation of coal cannot be fully met.

In order to reduce the consumption of hydrogen, researchers have attempted to utilize biomass with coal for pyrolysis hydrogenation. The hydrogen source for reaction with cracked coal fines in the kerosene co-refining technology comes mainly from: hydrogen dissolved in the hydrogen donor solvent is converted into active hydrogen under the action of a catalyst, hydrogen which can be supplied or transferred by the hydrogen donor solvent, active hydrogen generated by coal cracking and hydrogen generated by reaction. However, the H/C ratio of biomass is relatively high, and researchers hope to reduce the hydrogen consumption of coal liquefaction by using hydrogen in biomass, slow down the severity of reaction conditions, and achieve mild liquefaction of coal.

The mechanism of liquefaction of biomass is as follows: biomass is first cracked into oligomers, which are then dehydrated, dehydroxylated, dehydrogenated, deoxygenated and decarboxylated to form small molecule compounds, which are then reacted via condensation, cyclization, polymerization, etc. to produce new compounds. Research reports that products formed by pyrolysis of wood flour contribute to hydrogenation reactions of coal liquefaction intermediates (preasphaltene and asphaltene) to form liquid oil; the addition of biomass also facilitates the pyrolytic removal of sulfur and nitrogen from coal and prevents cohesion between particles during coal pyrolysis.

However, since the kerosene slurry has high viscosity, the addition of the biomass particles can further increase the viscosity and cannot be conveyed by a pump, so that the co-liquefaction of the coal and the biomass is limited to the dispersion of the coal dust and the biomass particles in a laboratory by using tetralin with low viscosity as a solvent. We have tried to use water as hydrogen donor solvent to carry out the co-liquefaction process of coal and biomass, but due to the characteristics of biomass, the slurry obtained has fluidity only at very low concentration, i.e. it is not possible to obtain biomass coal water slurry with high concentration and good fluidity at all, which results in that it is impossible to carry out the hydro-liquefaction reaction industrially because it cannot be pumped and is not good for the dispersion of catalyst.

In conclusion, how to improve the liquefaction efficiency of coal liquefaction and further reduce the viscosity of the biomass and coal co-pulping, thereby realizing the mixing of the coal and the biomass and reducing the hydrogen consumption is a technical problem which is not solved by the technical personnel in the field at present.

Disclosure of Invention

The invention firstly solves the technical problem of low liquefaction efficiency caused by limited coal powder content of coal slurry in the prior art, and further overcomes the defect that the prior art does not realize the pulping and mixing production technology of coal and biomass on the basis of the problem, thereby providing a method for producing light oil by liquefying coal and biomass with low hydrogen consumption and high yield of liquefied oil.

The technical scheme adopted by the invention for solving the problems is as follows:

a method for producing light oil by coal and biomass liquefaction comprises the following steps:

preparing the biomass coal water slurry:

collecting biomass, controlling the water content to be lower than 2 wt%, and then crushing the biomass to the median particle size of 100-300 mu m;

compressing and molding the crushed biomass, wherein the compression pressure is 2-5 MPa, and the compression temperature is 30-60 ℃;

crushing the compressed and molded biomass again to obtain biomass powder, wherein the median particle size of the crushed biomass powder is 30-50 microns;

collecting coal, controlling the water content to be lower than 2 wt%, and then crushing to obtain particles with a median diameter of 50-100 mu m, wherein the compression temperature is 30-60 ℃;

compressing and molding the crushed coal, wherein the compression pressure is 5-15 MPa;

crushing the compressed and molded coal again to obtain coal powder with median particle size of 30-50 μm;

mixing the biomass powder, the coal powder, a hydrogenation catalyst and water, grinding and pulping to obtain biomass coal water slurry, wherein the biomass powder and the coal powder account for 55-65 wt% of the biomass coal water slurry;

obtaining of hydrogenation products:

carrying out a first liquefaction reaction on the biomass coal water slurry and hydrogen, and collecting a first reaction product; carrying out a second liquefaction reaction on the first reactant and hydrogen, and collecting a second reaction product; carrying out first separation on the second reaction product, and collecting a light component and a heavy component; carrying out reduced pressure distillation on the heavy components, and collecting light fractions; mixing the light component and the light fraction to carry out hydrogenation reaction, and collecting a hydrogenation product;

separation of hydrogenation products:

fractionating the hydrogenation product to obtain light oil;

in the preparation step of the biomass coal water slurry, when mixing, the biomass powder and the coal powder are firstly subjected to ash removal and are premixed with the catalyst, and then the obtained premix is mixed with the water, or the biomass powder, the coal powder and the catalyst are directly mixed with the water.

In the biomass coal water slurry, the concentration of biomass is 15-30 wt%, and the concentration of coal powder is 35-50 wt%.

And controlling the water content by adopting drying dehydration, wherein the drying dehydration temperature is 50-70 ℃, and the drying dehydration time is 3-5 h.

Preparation of biomass coal water slurryIn the preparation step, the bulk density of the biomass powder is controlled to be 300-500 kg/m³Controlling the bulk density of the pulverized coal to be 1200-1300 kg/m³。

The grinding and pulping time is 2-8 min.

In the biomass coal water slurry, the mass ratio of the sum of the coal and the biomass to the hydrogenation catalyst is 100: (0.5-5).

In the step of obtaining the hydrogenation product, the reaction conditions of the first liquefaction reaction are as follows:

the reaction temperature is 350-470 ℃;

the reaction pressure is 15-27 MPa;

the gas-liquid ratio is 1000-1500L/kg;

the airspeed of the biomass coal water slurry is 0.3-1.5 h^-1。

The reaction conditions of the second liquefaction reaction are as follows:

the reaction temperature is 380-490 ℃;

the reaction pressure is 15-20 MPa;

the gas-liquid ratio is 1100-1700L/kg;

the airspeed of the biomass coal water slurry is 0.3-1.5 h^-1。

The temperature of the reduced pressure distillation is 320-400 ℃, and the pressure is 5-20 kPa. .

The reaction conditions of the hydrogenation reaction are as follows:

the reaction temperature is 380-440 ℃;

the reaction pressure is 15-25 MPa;

the volume ratio of the hydrogen to the oil is 1000-1500;

the airspeed is 0.3-1 h^-1。

The temperature of the fractionation is 340-390 ℃.

And collecting a part of distillate oil obtained after the vacuum distillation step and a heavy fraction obtained in the fractionation step, and taking the part of distillate oil and the heavy fraction as the solvent oil.

Before fractionation, the hydrogenation product also comprises a step of carrying out secondary separation on the hydrogenation product to respectively obtain hydrogen, gas-phase light hydrocarbon and a liquid phase, and the hydrogen is circularly used in the first liquefaction reaction, the second liquefaction reaction and the hydrogenation reaction.

The hydrogenation catalyst is at least one of the following catalysts:

1) amorphous iron oxide and/or amorphous iron oxyhydroxide;

2) amorphous alumina loaded with active ingredients, wherein the active ingredients are at least one of VIB metal, VIIB metal or VIII metal oxides, and the content of the active ingredients is 10-25 wt%;

the coal is low-rank coal.

Compared with the prior art, the invention has the following beneficial effects:

1. the invention creatively realizes the mixing liquefaction of coal and biomass by using water as a hydrogen supply solvent for the first time, and provides a method for producing light oil by coal and biomass liquefaction. According to the invention, biomass and coal water slurry with biomass and coal content of 55-65 wt% and viscosity of 450-1100 mPa & s (50 ℃) is successfully prepared by the process flow of biomass and coal dehydration, crushing, compression, re-crushing, primary pulping and grinding pulping, and optimization of crushed particle size and compression conditions.

The compression treatment can collapse and close the pore structures in the coal and biomass materials, and plastic rheology and plastic deformation occur, so that the density of the coal and biomass raw materials is greatly improved, and the coal and biomass raw materials can be well dispersed in water; meanwhile, the collapse and the closure of the pore structure avoid the adsorption of coal and biomass on water, so that the water can fully play the role of the water as a dispersing agent; we have found that the compression temperature has a great influence on the degree of plastic rheology and plastic deformation, the higher the temperature is, the higher the density is, however, the higher the temperature is, the material decomposition or other problems may be caused, so 30-60 ℃ is adopted as the compression temperature. The operation of smashing once more after the compression has increased the contactable area of raw materials for raw materials can better contact with catalyst and water, can strengthen the transmission of hydrogen, thereby the condition that the raw materials can't contact with hydrogen and catalyst and react because of being in pore form structure is greatly reduced.

The invention provides the method of 'crushing, compressing and re-crushing' which is suitable for all coal materials and biomass materials with internal pore structures, in particular low-rank coal raw materials such as brown coal and the like, and porous and loose biomass raw materials such as straws and rice hulls; the prepared high-concentration biomass coal water slurry has good slurrying property and high fluidity, can be directly and stably conveyed by a pump, not only can effectively improve the operation stability of a conveying system, the utilization efficiency of a liquefying device and the liquefying efficiency, meet the feeding requirement of a subsequent treatment process, but also realizes the clean and efficient utilization of inferior coal and biomass; the close proximity of coal and biomass allows hydrogen produced by biomass pyrolysis to be used as part of the hydrogen source for coal pyrolysis hydrogenation, reducing hydrogen consumption.

According to the invention, through two liquefaction reactions, the coal and the biomass can be fully liquefied into a liquid phase, and the liquid oil yield is improved. Separating the product obtained by the second liquefaction reaction, collecting light components and heavy components, then carrying out reduced pressure distillation on the heavy components, collecting light fractions, mixing the light components and the light fractions for hydrogenation reaction, separating the light fractions mixed in the heavy components by reduced pressure distillation, and simultaneously separating heavy fractions difficult to be hydrogenated and liquefied, thereby being beneficial to the conversion of subsequent light oil; a small amount of heavy components which are easy to lighten and are included in the light components can be converted into the light components through hydrogenation reaction, so that the yield of the light oil is improved, and particularly the yield of low-boiling-point oil such as naphtha in the light oil is improved; and the residues are enriched and agglomerated as much as possible, so that the residues can be removed from the bottom of the reduced pressure distillation device, and the content of the residues in the subsequent light oil is reduced. Through test, the liquefaction rate of the coal and the biomass can reach 97-99%, in the obtained liquefied oil, the fraction below 145 ℃ accounts for 30-50 wt%, the fraction between 145 ℃ and 360 ℃ accounts for 20-30 wt%, the fraction between 360 ℃ and 520 ℃ accounts for 20-40 wt%, the balance is heavy oil with the distillation range above 520 ℃ and the residue content is not more than 4 wt%.

2. The method for producing the light oil by liquefying the coal and the biomass further cooperates with the process of screening the solid materials, can ensure that the particle size of solid particles for preparing the raw biomass coal water slurry is uniform, ensures that the obtained biomass coal water slurry has better stability, is not easy to settle in the transportation process, and avoids the blockage of a transportation pipeline and the damage to liquefaction equipment. The solid biomass is pretreated by drying, crushing, ash removal and the like, and then is mixed with the catalyst, so that the surface energy of the coal and biomass powder is better utilized to enable the catalyst to be attached to the surface of the coal and biomass powder, and the catalyst can timely provide hydrogen transfer for the coal and biomass hydrolysate, thereby ensuring that the coke polycondensation cannot be generated in the whole process and achieving the purpose of reducing the coke production.

By collecting part of distillate oil obtained after the reduced pressure distillation step and heavy fraction obtained in the fractionation step and adding the distillate oil into the first liquefaction reaction, the utilization rate of raw materials can be improved, and the process cost can be reduced.

3. According to the method for producing the light oil by coal and biomass liquefaction, provided by the invention, the hydrogenation product is further subjected to secondary separation before being fractionated, so that hydrogen which can be recycled in the first liquefaction reaction, the second liquefaction reaction and the hydrogenation reaction is obtained.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a schematic view of a process flow for preparing a biomass coal-water slurry in example 1.

FIG. 2 is a schematic view of the process flow for producing light oil from liquefaction of biomass coal water slurry in example 1.

Fig. 3 is a schematic process flow diagram of the process for producing light oil by liquefying coal and biomass provided in example 4.

Reference numerals:

1-water; 2-biomass and coal; 201-jet mill; 202-plodder; 203-hammer mill; 204-a vibrating screen; 205-mixing bowl with shears; 206-colloid mill; 207-ball mill; 208-briquetting machine; 209-ultrafine pulverizer; 3-a hydrogenation catalyst; 4-biomass water-coal slurry tank; 5-a suspended bed reactor; 6-internal circulation suspension bed reactor; 7-suspension bed hydrogenation products; 8-a hot high pressure separator; 9-light component; 10-heavy ends; 11-a high differential pressure relief valve; 12-a vacuum column; 13-overhead oil; 14-side distillate; 15-fixed bed hydrogenation reactor; 16-fixed bed hydrogenation product; 17-a separator; 18-hydrogen; 19-gas phase light hydrocarbons; 20-distillate oil; 21-a fractionation column; 22-biomass naphtha; 23-biodiesel; 24-biomass tower bottoms oil; 25-residue; 26-hydrogen.

Detailed Description

To better illustrate the objects, aspects and advantages of the present invention, the present invention will be further described with reference to specific embodiments. This invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concept of the invention to those skilled in the art, and the present invention will only be defined by the appended claims.

In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

The calculation formulas of the conversion rate of the coal and the biomass, the bio-oil yield, the content of the bio-oil in each distillation range in the distillate and the residue content in each example and comparative example are as follows:

conversion of coal to biomass ═ (mass of second reaction product-mass of hydrogenation catalyst-mass of water)/(mass sum of coal and biomass)

Yield of bio-oil (mass of hydrogenation product/(mass sum of coal and biomass)

The content of the bio-oil in each distillation range in the distillate oil is equal to the mass of the bio-oil/the total mass of the bio-oil.

Residue content is residue mass/(mass sum of coal and biomass).

Example 1

The embodiment provides a method for producing light oil by coal and biomass liquefaction, which comprises the following steps as shown in figures 1 and 2:

pretreatment of the biomass raw material:

(1) pulverizing soybean oil residue in jet mill 201 to obtain soybean oil residue material with particle diameter D₅₀And 200 μm.

(2) The soybean oil residue crushed material is sent into a plodder 202 for extrusion forming, and the forming pressure is 2MPa, so that the soybean oil residue compressed material is obtained.

(3) Feeding the soybean oil residue compressed material into a hammer mill for secondary crushing to obtain a secondary crushed material of soybean oil residue with a particle size D₅₀Is 40 μm for standby.

Pretreating a coal raw material:

(1) taking lignite, drying and dehydrating the lignite, and then sending the lignite into a ball mill 207 for crushing treatment to obtain primary crushed lignite with a particle size D₅₀Is 100 μm.

(2) The lignite primary crushed material is sent into a briquetting machine 208 for extrusion forming, and the forming pressure is 15MPa, so that the lignite compressed material is obtained.

(3) Feeding the brown coal compressed material into a superfine pulverizer 209 for secondary pulverization to obtain brown coal secondary pulverized material with a particle size D₅₀Is 30 μm for standby.

The secondary crushed material of the algae and the lignite is sent to a vibrating screen 204 for screening, the algae with the particle size larger than 80 mu m and the lignite are separated, and then the secondary crushed material is put into a compression link or a secondary crushing link and then is subjected to secondary treatment together with subsequent feeding to obtain more uniform particle size, so that more stable biomass coal water slurry is obtained.

Preparing the biomass coal water slurry:

deashing the screened secondary crushed material of the soybean oil dregs and the lignite, and then feeding the ash, amorphous alumina (the grain diameter of the amorphous alumina is 5-50 μm, the load is 10 wt%, and the first catalyst) loaded with Mo oxide and Ni oxide and sulfur into a mixing tank 205 with a shearing machine for mixing, wherein the secondary crushed material of the soybean oil dregs and the lignite: a first catalyst: the mass ratio of sulfur is 100: 5: 0.3. after uniform mixing, adding water into the mixing tank, opening the shearing machine, and carrying out initial preparation of the biomass coal water slurry at 60 ℃. And then, the initial slurry passes through a colloid mill 206 to obtain the biomass coal water slurry with better slurrying performance and more stability. In the biomass coal water slurry, the content of soybean oil residue is 15 wt%, and the content of coal is 40 wt%.

Hydrogenation reaction and product separation:

(1) carrying out a first liquefaction reaction on the biomass coal water slurry prepared in the step and the additional hydrogen 26 in the suspension bed reactor 5, and collecting a first reaction product, wherein the conditions of the first liquefaction reaction are as follows: the reaction temperature is 320 ℃, the reaction pressure is 20MPa, the gas-liquid ratio is 1000L/kg, and the airspeed of the biomass coal water slurry is 1h^-1；

(2) And (3) carrying out a second liquefaction reaction on the first reaction product and hydrogen in an internal circulation suspension bed reactor 6, and collecting a second reaction product, namely a suspension bed hydrogenation product 7, wherein the parameters of the second liquefaction reaction are as follows: the reaction temperature is 400 ℃, the reaction pressure is 20MPa, the gas-liquid ratio is 1100L/kg, and the airspeed of the biomass coal water slurry is 1h^-1；

(3) Carrying out first separation on the second reaction product in a hot high-pressure separator 8 under the pressure of 19MPa, and collecting a light component 9 and a heavy component 10;

(4) the heavy component 10 is depressurized by a high-pressure-difference depressurization valve 11 and then enters a depressurization tower 12, the pressure is reduced and distilled at the temperature of 360 ℃ and the pressure of 10kPa, light fractions, namely tower top oil 13 and side distillate oil 14 in the depressurization tower 12 are collected, and residue 25 is recovered from the bottom of the depressurization tower 12;

(5) mixing the light component 9 with the tower top oil 13, feeding the mixture into a fixed bed hydrogenation reactor 16 for hydrogenation reaction, and collecting a fixed bed hydrogenation product 16, wherein the hydrogenation reaction conditions are as follows: the reaction temperature is 400 ℃, the reaction pressure is 17MPa, the hydrogen-oil volume ratio is 1100, and the space velocity is 1.2h^-1；

(6) The fixed bed hydrogenation product 16 enters a separator 17 for second separation to obtain hydrogen 18, gas-phase light hydrocarbon 19 and liquid phase, namely distillate oil 20, wherein the hydrogen 18 can be used in the first liquefaction reaction, the second liquefaction reaction and the hydrogenation reaction, and the gas-phase light hydrocarbon 19 is recycled;

(7) the distillate oil 20 enters a fractionating tower 21 and is fractionated at 360 ℃, naphtha is separated from the top of the tower, diesel oil is separated from the middle upper part of the tower, and bottom oil 24, namely heavy fraction, is discharged from the bottom of the tower.

Example 2

The embodiment provides a method for producing light oil by coal and biomass liquefaction, which comprises the following steps:

pretreatment of the biomass raw material:

(1) drying and dehydrating reed, and pulverizing with jet mill to obtain crushed material with particle diameter D₅₀Is 100 μm.

(2) And (3) feeding the once crushed reed material into a plodder for extrusion molding, wherein the molding pressure is 3MPa, so as to obtain the reed compressed material.

(3) Feeding the compressed reed material into a jet mill for secondary crushing to obtain secondary crushed reed material with a particle size D₅₀Is 30 μm for standby.

Pretreating a coal raw material:

(1) drying and dehydrating the Shendong long flame coal, and then feeding the dried and dehydrated Shendong long flame coal into a ball mill for crushing to obtain the Shendong long flame coal primary crushed material with the particle size D₅₀Is 50 μm.

(2) And (3) feeding the crushed material of the Shendong long flame coal into a briquetting machine for extrusion forming, wherein the forming pressure is 12MPa, so as to obtain the Shendong long flame coal compressed material.

(3) Feeding the Shendong long flame coal compressed material into a ball mill for secondary crushing to obtain a Shendong long flame coal secondary crushed material with a particle size D₅₀100 μm for use.

Preparing the biomass coal water slurry:

as shown in fig. 3, the secondary crushed material of reed and shendong long flame coal, amorphous alumina loaded with W oxide and Ni oxide (the particle size is 100 μm-150 μm, the loading is 25%) and sulfur are mixed according to the mass ratio of 100: 1: 0.4 mixing evenly in a biomass water coal slurry tank 4 to obtain a mixture, adding water into the tank, and mixing evenly at 50 ℃ to form the biomass water coal slurry. In the biomass coal water slurry, the content of the reed is 30 wt%, and the content of the coal is 35 wt%.

Hydrogenation reaction and product separation:

the hydrogenation reaction and the separation process of the product in this example are schematically shown in FIG. 3.

(1) Carrying out a first liquefaction reaction on the biomass coal water slurry and the added hydrogen 26 in the suspension bed reactor 5, and collecting a first reaction product, wherein the parameters of the first liquefaction reaction are as follows: the reaction temperature is 300 ℃, the reaction pressure is 25MPa, the gas-liquid ratio is 1200L/kg, and the airspeed of the biomass coal water slurry is 2h^-1；

(2) And (3) carrying out a second liquefaction reaction on the first reaction product and hydrogen in an internal circulation suspension bed reactor 6, and collecting a second reaction product, namely a suspension bed hydrogenation product 7, wherein the parameters of the second liquefaction reaction are as follows: the reaction temperature is 420 ℃, the reaction pressure is 15MPa, the gas-liquid ratio is 1600L/kg, and the airspeed of the biomass coal water slurry is 0.3h^-1；

(3) Carrying out first separation on the second reaction product in a hot high-pressure separator 8 under the pressure of 15MPa, and collecting a light component 9 and a heavy component 10;

(4) the heavy component 10 is depressurized by a high pressure difference depressurization valve 11 and then enters a depressurization tower 12, the pressure is reduced and distilled at the temperature of 400 ℃ and the pressure of 5kPa, light fractions, namely tower top oil 13 and side distillate oil 14 in the depressurization tower 12 are collected, and residue 25 is recovered from the bottom of the depressurization tower 12;

(5) mixing the light component 9 with the tower top oil 13, feeding the mixture into a fixed bed hydrogenation reactor 16 for hydrogenation reaction, and collecting a fixed bed hydrogenation product 16, wherein the hydrogenation reaction conditions are as follows: the reaction temperature is 440 ℃, the reaction pressure is 15MPa, the hydrogen-oil volume ratio is 1500, and the space velocity is 0.3h^-1；

(7) the distillate oil 20 enters a fractionating tower 21 and is fractionated at 390 ℃, naphtha is separated from the top of the tower, diesel oil is separated from the middle upper part of the tower, and bottom oil 24, namely heavy fraction, is discharged from the bottom of the tower.

Example 3

pretreatment of the biomass raw material:

(1) taking leaves, drying and dehydrating the leaves, and then sending the leaves into a jet mill for crushing treatment to obtain primary crushed material of the leaves with the particle size D₅₀And 300 μm.

(2) And (3) sending the primary crushed material of the leaves into a briquetting machine or a plodder for extrusion forming, wherein the forming pressure is 5MPa, and obtaining the compressed material of the leaves.

(3) Feeding the compressed leaf material into a jet mill, and performing secondary grinding to obtain secondary crushed material with particle size D₅₀50 μm for use.

Pretreating a coal raw material:

(1) drying and dehydrating the Shendong long flame coal, and then feeding the dried and dehydrated Shendong long flame coal into a ball mill for crushing to obtain the Shendong long flame coal primary crushed material with the particle size D₅₀And 80 μm.

(2) And (3) sending the crushed material of the Shendong long flame coal into a briquetting machine or a plodder for extrusion forming, wherein the forming pressure is 5MPa, so as to obtain the Shendong long flame coal compression material.

(3) Feeding the Shendong long flame coal compressed material into a ball mill for secondary crushing to obtain a Shendong long flame coal secondary crushed material with a particle size D₅₀70 μm for use.

Preparing the biomass coal water slurry:

mixing the secondary crushed material of the leaves and the coal with amorphous alumina loaded with Pd oxide and Ni oxide (the particle size is 100-150 mu m, the loading is 10%), amorphous iron oxide and sulfur according to the mass ratio of 100: 2: 2: 0.3, adding the mixture into a biomass water coal slurry tank 4, adding water, and uniformly mixing at 65 ℃ to form biomass water coal slurry; in the biomass coal water slurry, the content of the leaves is 25 wt%, and the content of the coal is 40 wt%.

Liquefaction reaction and separation of products:

(1) carrying out a first liquefaction reaction on the biomass coal water slurry and the added hydrogen 26 in the suspension bed reactor 5, and collecting a first reaction product, wherein the parameters of the first liquefaction reaction are as follows: the reaction temperature is 420 ℃, the reaction pressure is 15MPa, the gas-liquid ratio is 1500L/kg, and the airspeed of the biomass coal water slurry is 0.3h^-1；

(2) And (3) carrying out a second liquefaction reaction on the first reaction product and hydrogen in an internal circulation suspension bed reactor 6, and collecting a second reaction product, namely a suspension bed hydrogenation product 7, wherein the parameters of the second liquefaction reaction are as follows: the reaction temperature is 350 ℃, the reaction pressure is 17MPa, the gas-liquid ratio is 1700L/kg, and the airspeed of the biomass coal water slurry is 2h^-1；

(4) the heavy component 10 is depressurized by a high-pressure-difference depressurization valve 11 and then enters a depressurization tower 12, the pressure is reduced and distilled at the temperature of 320 ℃ and the pressure of 20kPa, light fractions, namely tower top oil 13 and side distillate oil 14 in the depressurization tower 12 are collected, and residue 25 is recovered from the bottom of the depressurization tower 12;

(5) mixing the light component 9 with the tower top oil 13, feeding the mixture into a fixed bed hydrogenation reactor 16 for hydrogenation reaction, and collecting a fixed bed hydrogenation product 16, wherein the hydrogenation reaction conditions are as follows: the reaction temperature is 450 ℃, the reaction pressure is 26MPa, the hydrogen-oil volume ratio is 1000, and the space velocity is 1.5h^-1；

(7) the distillate oil 20 enters a fractionating tower 21 and is fractionated at 300 ℃, naphtha is separated from the top of the tower, diesel oil is separated from the middle upper part of the tower, and bottom oil 24, namely heavy fraction, is discharged from the bottom of the tower.

Example 4

pretreatment of the biomass raw material:

(1) drying and dehydrating algae, pulverizing to particle size of 150 μm, and extruding with a plodder under molding pressure of 2MPa to obtain algae compressed material.

(2) Feeding the algae compressed material into a jet mill, and pulverizing to obtain algae pulverized material with particle size D₅₀Is 40 μm for standby.

Pretreating a coal raw material:

(1) taking lignite, drying and dehydrating the lignite, crushing the lignite to 65 mu m of median particle size, and then sending the lignite into a briquetting machine for extrusion forming at the forming pressure of 15MPa to obtain the lignite compressed material.

(2) Sending the brown coal compressed material into a ball mill for crushing to obtain brown coal powder crushed material with the particle size D₅₀50 μm for use.

Screening the crushed materials of the algae and the lignite, separating the lignite with the particle size larger than 100 mu m, and then putting the separated lignite into a compression link or a secondary crushing link for subsequent feeding and retreating together to obtain more uniform particle size so as to obtain more stable biomass coal water slurry.

Preparing the biomass coal water slurry:

mixing the screened secondary crushed materials of the algae and the lignite with amorphous alumina loaded with Mo oxide and Co oxide (the grain diameter is 150-200 mu m, the loading amount is 13%) and sulfur according to the mass ratio of 100: 3: 0.2, uniformly mixing the mixture in a biomass water coal slurry tank 4 to obtain a mixture, adding water into the mixture, and uniformly mixing the mixture at the temperature of 70 ℃ to form the biomass water coal slurry, wherein the biomass water coal slurry contains 30 wt% of algae and 35 wt% of coal.

Hydrolysis reaction and product separation：

(1) Carrying out a first liquefaction reaction on the biomass coal water slurry and the added hydrogen 26 in the suspension bed reactor 5, and collecting a first reaction product, wherein the parameters of the first liquefaction reaction are as follows: the reaction temperature is 420 ℃, the reaction pressure is 18MPa, the gas-liquid ratio is 1500L/kg, and the airspeed of the biomass coal water slurry is 2h^-1；

(2) And (3) carrying out a second liquefaction reaction on the first reaction product and hydrogen in an internal circulation suspension bed reactor 6, and collecting a second reaction product, namely a suspension bed hydrogenation product 7, wherein the parameters of the second liquefaction reaction are as follows: the reaction temperature is 350 ℃, the reaction pressure is 18MPa, the gas-liquid ratio is 1200L/kg, and the airspeed of the biomass coal water slurry is 1.5h^-1；

(3) Carrying out first separation on the second reaction product in a hot high-pressure separator 8 under the pressure of 22MPa, and collecting a light component 9 and a heavy component 10;

(4) the heavy component 10 is depressurized by a high-pressure-difference depressurization valve 11 and then enters a depressurization tower 12, the pressure is reduced and distilled at the temperature of 380 ℃ and the pressure of 8kPa, light fractions, namely tower top oil 13 and side distillate oil 14 in the depressurization tower 12 are collected, and residue 25 is recovered from the bottom of the depressurization tower 12;

(7) the distillate oil 20 enters a fractionating tower 21 and is fractionated at 330 ℃, naphtha is separated from the top of the tower, diesel oil is separated from the middle upper part of the tower, and bottom oil 24, namely heavy fraction, is discharged from the bottom of the tower.

Example 5

pretreatment of the biomass raw material:

(1) drying soybean oil residue, dewatering, pulverizing with superfine pulverizer to obtain soybean oil residue material with particle diameter D₅₀And 200 μm.

(2) And (3) feeding the crushed soybean oil residue into a briquetting machine or a plodder for extrusion forming, wherein the forming pressure is 4MPa, so as to obtain the soybean oil residue compressed material.

(3) Feeding the soybean oil residue compressed material into an ultrafine pulverizer, and performing secondary pulverization to obtain a secondary pulverized material of soybean oil residue with a particle size D₅₀Is 40 μm for standby.

Pretreating a coal raw material:

(2) And (3) sending the crushed material of the Shendong long flame coal into a briquetting machine or a plodder for extrusion forming, wherein the forming pressure is 10MPa, so as to obtain the Shendong long flame coal compression material.

(3) Feeding the Shendong long flame coal compressed material into a ball mill for secondary crushing to obtain a Shendong long flame coal secondary crushed material with a particle size D₅₀50 μm for use.

Of course, as an alternative to this embodiment, the soybean oil residue compressed material and the mindong long flame coal compressed material may be mixed with water and then sent to the ball mill together for the second pulverization.

Preparing the biomass coal water slurry:

mixing the soybean oil residue and the secondary crushed material of coal with amorphous alumina loaded with W oxide and Co oxide (the particle size is 250-350 μm, the loading amount is 42 wt%), amorphous iron oxyhydroxide and sulfur according to the mass ratio of 100: 1: 2: 0.25 is evenly mixed in the biomass water coal slurry tank 4 to obtain a mixture, and then water is added into the mixture to be evenly mixed at the temperature of 75 ℃ to form the biomass water coal slurry. The content of soybean oil residue in the biomass coal water slurry is 20 wt%, and the content of coal is 40 wt%.

Liquefaction reaction and separation of products:

(1) carrying out a first liquefaction reaction on the biomass coal water slurry and the added hydrogen 26 in the suspension bed reactor 5, and collecting a first reaction product, wherein the parameters of the first liquefaction reaction are as follows: the reaction temperature is 360 ℃, the reaction pressure is 21MPa, the gas-liquid ratio is 1300L/kg, and the airspeed of the biomass coal water slurry is 1.1h^-1；

(2) And (3) carrying out a second liquefaction reaction on the first reaction product and hydrogen in an internal circulation suspension bed reactor 6, and collecting a second reaction product, namely a suspension bed hydrogenation product 7, wherein the parameters of the second liquefaction reaction are as follows: the reaction temperature is 420 ℃, the reaction pressure is 20MPa, the gas-liquid ratio is 1300L/kg, and the airspeed of the biomass coal water slurry is 1.6h^-1；

(3) Carrying out first separation on the second reaction product in a hot high-pressure separator 8 under the pressure of 21MPa, and collecting a light component 9 and a heavy component 10;

(4) the heavy component 10 is depressurized by a high-pressure-difference depressurization valve 11 and then enters a depressurization tower 12, the pressure is reduced and distilled at the temperature of 330 ℃ and the pressure of 11kPa, light fractions, namely tower top oil 13 and side distillate oil 14 in the depressurization tower 12 are collected, and residue 25 is recovered from the bottom of the depressurization tower 12;

(5) mixing the light component 9 with the tower top oil 13, feeding the mixture into a fixed bed hydrogenation reactor 16 for hydrogenation reaction, and collecting a fixed bed hydrogenation product 16, wherein the hydrogenation reaction conditions are as follows: the reaction temperature is 430 ℃, the reaction pressure is 20MPa, the hydrogen-oil volume ratio is 1000, and the space velocity is 0.3h^-1；

(7) the distillate oil 20 enters a fractionating tower 21 and is fractionated at 280 ℃, naphtha is separated from the top of the tower, diesel oil is separated from the middle upper part of the tower, and bottom oil 24, namely heavy fraction, is discharged from the bottom of the tower.

Example 6

pretreatment of the biomass raw material:

(1) drying and dehydrating wheat straw, and then feeding the wheat straw into a jet mill for crushing treatment to obtain primary crushed material of the wheat straw with particle size D₅₀And 200 μm.

(2) And (3) sending the wheat straw primary crushed material into a briquetting machine or a plodder for extrusion forming, wherein the forming pressure is 2MPa, so as to obtain the wheat straw compressed material.

(3) Sending the compressed wheat straw material into a jet mill for secondary crushing to obtain secondary crushed material of wheat straw with particle size D₅₀Is 40 μm for standby.

Pretreating a coal raw material:

(1) taking brown coal, drying and dehydrating the brown coal, and then sending the brown coal into a ball mill for crushing treatment to obtain primary crushed material of the brown coal with a particle size D₅₀And 80 μm.

(2) And (3) conveying the primary pulverized lignite into a briquetting machine or a plodder for extrusion molding, wherein the molding pressure is 15MPa, so as to obtain the compressed lignite.

(3) Sending the brown coal compressed material into a ball mill for secondary crushing to obtain brown coal secondary crushed material with the particle size D₅₀80 μm for use.

Screening the secondarily-crushed materials of the wheat straws and the lignite, separating the wheat straws with the particle size larger than 100 mu m from the lignite, and then putting the wheat straws and the lignite into a compression link or a secondary crushing link for subsequent feeding and secondary treatment to obtain more uniform particle size, thereby obtaining more stable biomass coal water slurry.

Preparing the biomass coal water slurry:

mixing the screened secondary crushed materials of wheat straws and lignite with amorphous alumina loaded with Mo oxide and Ni oxide (the particle size is 350-500 mu m, the loading amount is 40 wt%), amorphous iron oxide and sulfur according to the mass ratio of 100: 1: 1: 0.1 mixing the materials in a biomass water coal slurry tank 4 to obtain a mixture, adding water into the mixture, and mixing the mixture at the temperature of 55 ℃ to form the biomass water coal slurry. The obtained biomass coal water slurry contains 30 wt% of wheat straws and 35 wt% of lignite.

Liquefaction reaction and separation of products:

(1) carrying out a first liquefaction reaction on the biomass coal water slurry and the added hydrogen 26 in the suspension bed reactor 5, and collecting a first reaction product, wherein the parameters of the first liquefaction reaction are as follows: the reaction temperature is 300 ℃, the reaction pressure is 25MPa, the gas-liquid ratio is 1000L/kg, and the airspeed of the biomass coal water slurry is 2h^-1；

(2) And (3) carrying out a second liquefaction reaction on the first reaction product and hydrogen in an internal circulation suspension bed reactor 6, and collecting a second reaction product, namely a suspension bed hydrogenation product 7, wherein the parameters of the second liquefaction reaction are as follows: the reaction temperature is 410 ℃, the reaction pressure is 18MPa, the gas-liquid ratio is 1000L/kg, and the space velocity of the biomass coal water slurry is 2h^-1；

(5) mixing the light component 9 with the tower top oil 13, feeding the mixture into a fixed bed hydrogenation reactor 16 for hydrogenation reaction, and collecting a fixed bed hydrogenation product 16, wherein the hydrogenation reaction conditions are as follows: the reaction temperature is 450 ℃, the reaction pressure is 20MPa, the hydrogen-oil volume ratio is 1000, and the space velocity is 1.5h^-1；

(6) The fixed bed hydrogenation product 16 enters a fractionating tower 21 and is fractionated at 280 ℃, naphtha is separated from the top of the tower, diesel oil is separated from the middle upper part of the tower, and bottom oil 24, namely heavy fraction, is discharged from the bottom of the tower.

Example 7

treatment of biomass and coal raw materials:

taking rice straws, palm oil residues and lignite, drying, dehydrating and crushing the rice straws, the palm oil residues and the lignite, and then sending the materials into a briquetting machine together for extrusion molding, wherein the molding pressure is 5MPa, so as to obtain the compressed materials of the rice straws, the palm oil residues and the lignite. And (3) feeding the compressed material into a ball mill, and crushing to obtain crushed materials of rice straws, palm oil residues and lignite for later use.

Preparing the biomass coal water slurry:

mixing the crushed material, amorphous alumina loaded with W oxide and Ni oxide (the particle size is 100-150 mu m, the loading amount is 25%) and sulfur according to the mass ratio of 100: 1: 0.4 evenly mixing the mixture in a biomass water coal slurry tank 4 to obtain a mixture, adding the mixture into water, and evenly mixing the mixture at 180 ℃ to form the biomass water coal slurry. The obtained biomass water-coal slurry contains 15 wt% of rice straws and palm oil residues and 50 wt% of lignite.

Liquefaction reaction and separation of products:

(1) carrying out a first liquefaction reaction on the biomass coal water slurry and the added hydrogen 26 in the suspension bed reactor 5, and collecting a first reaction product, wherein the parameters of the first liquefaction reaction are as follows: the reaction temperature is 420 ℃, the reaction pressure is 23MPa, the gas-liquid ratio is 1000L/kg, and the airspeed of the biomass coal water slurry is 2h^-1；

(2) And (3) carrying out a second liquefaction reaction on the first reaction product and hydrogen in an internal circulation suspension bed reactor 6, and collecting a second reaction product, namely a suspension bed hydrogenation product 7, wherein the parameters of the second liquefaction reaction are as follows: the reaction temperature is 420 ℃, the reaction pressure is 20MPa, the gas-liquid ratio is 1500L/kg, and the airspeed of the biomass coal water slurry is 0.3h^-1；

(5) mixing the light component 9 with the tower top oil 13, feeding the mixture into a fixed bed hydrogenation reactor 16 for hydrogenation reaction, and collecting a fixed bed hydrogenation product 16, wherein the hydrogenation reaction conditions are as follows: the reaction temperature is 440 ℃, the reaction pressure is 26MPa, the hydrogen-oil volume ratio is 1500, and the space velocity is 0.5h^-1；

Comparative example 1

The comparative example provides a method for producing light oil by coal and biomass liquefaction, comprising the following steps:

pretreatment of the biomass raw material:

(1) drying and dehydrating soybean oil residue, and pulverizing with jet mill 201 to obtain soybean oil residue primary pulverized material with particle diameter D₅₀And 200 μm.

Pretreating a coal raw material:

(1) taking brown coal, drying and dehydrating the brown coal, and then sending the brown coal into a ball mill 207 for crushing treatment to obtain the brown coalCrushed material of particle size D₅₀And 80 μm.

(3) Feeding the brown coal compressed material into a superfine pulverizer 209 for secondary pulverization to obtain brown coal secondary pulverized material with a particle size D₅₀80 μm for use.

The secondary crushed material of the algae and the lignite is sent to a vibrating screen 204 for screening, the algae with the particle size larger than 40 mu m and the lignite with the particle size larger than 100 mu m are separated, and then the separated algae and the lignite are put into a compression link or a secondary crushing link and then are fed for secondary treatment together, so that more uniform particle size is obtained, and more stable biomass coal water slurry is obtained.

Preparing the biomass coal water slurry:

deashing the screened secondary crushed material of the soybean oil dregs and the lignite, and then feeding the ash, amorphous alumina (the grain diameter of the amorphous alumina is 5-50 μm, the load is 10 wt%, and the first catalyst) loaded with Mo oxide and Ni oxide and sulfur into a mixing tank 205 with a shearing machine for mixing, wherein the secondary crushed material of the soybean oil dregs and the lignite: a first catalyst: the mass ratio of sulfur is 100: 5: 0.3. after uniform mixing, adding water into the mixing tank, opening the shearing machine, and carrying out initial preparation of the biomass coal water slurry at 100 ℃. And then, the initial slurry passes through a colloid mill 206 to obtain the biomass coal water slurry with better slurrying performance and more stability. In the biomass coal water slurry, the content of soybean oil residue is 15 wt%, and the content of coal is 50 wt%.

Hydrogenation reaction and product separation:

(2) Carrying out a second liquefaction reaction on the first reaction product and hydrogen in an internal circulation suspension bed reactor 6, and collectingCollecting a second reaction product, namely a suspension bed hydrogenation product 7, wherein the parameters of the second liquid-phase reaction are as follows: the reaction temperature is 400 ℃, the reaction pressure is 20MPa, the gas-liquid ratio is 1100L/kg, and the airspeed of the biomass coal water slurry is 1h^-1；

(3) The second reaction product is subjected to a first separation in a hot high pressure separator 8 at a pressure of 19MPa, collecting the light fraction 9 and the heavy fraction 10.

The process results provided by the above examples and comparative examples are shown in the following table.

TABLE 1 conversion and oil testing for the examples and comparative examples

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.

Claims

1. A method for producing light oil by coal and biomass liquefaction is characterized by comprising the following steps:

preparing the biomass coal water slurry:

crushing the compressed and molded coal again to obtain coal powder with median particle size of 30-100 microns;

obtaining of hydrogenation products:

separation of hydrogenation products:

fractionating the hydrogenation product to obtain light oil;

2. The method for producing the light oil by liquefying the coal and the biomass according to claim 1, wherein in the biomass coal-water slurry, the concentration of the biomass is 15-30 wt%, and the concentration of the pulverized coal is 35-50 wt%.

3. The method for producing the light oil by liquefying the coal and the biomass as claimed in claim 1 or 2, wherein the moisture content is controlled by drying and dehydrating at the temperature of 50-70 ℃ for 3-5 h.

4. The method for producing the light oil by liquefying the coal and the biomass according to claim 1-2, wherein the bulk density of the biomass powder is controlled to be 300-500 kg/m in the preparation step of the biomass coal-water slurry³Controlling the bulk density of the pulverized coal to be 1200-1300 kg/m³。

5. The method for producing the light oil by liquefying the coal and the biomass as claimed in claim 1 or 2, wherein the time for grinding and pulping is 2-8 min.

6. The method for producing light oil by liquefying coal and biomass according to claim 1 or 2, wherein in the biomass coal-water slurry, the mass ratio of the sum of the coal and the biomass to the hydrogenation catalyst is 100: (0.5-5).

7. The method for producing light oil by coal and biomass liquefaction according to claim 1 or 2, wherein in the step of obtaining the hydrogenation product, the reaction conditions of the first liquefaction reaction are as follows:

the reaction temperature is 300-420 ℃;

the reaction pressure is 15-25 MPa;

the gas-liquid ratio is 1000-1500L/kg;

the airspeed of the biomass coal water slurry is 0.3-2 h^-1。

8. The method for producing light oil by coal and biomass liquefaction according to claim 1 or 2, wherein the reaction conditions of the second liquefaction reaction are as follows:

the reaction temperature is 350-420 ℃;

the reaction pressure is 15-20 MPa;

the gas-liquid ratio is 1100-1700L/kg;

the airspeed of the biomass coal water slurry is 0.3-1.5 h^-1。

9. The method for producing the light oil by liquefying the coal and the biomass according to claim 1 or 2, wherein the temperature of the reduced pressure distillation is 320-400 ℃, and the pressure is 5-20 kPa.

10. The method for producing light oil by coal and biomass liquefaction according to claim 1 or 2, wherein the reaction conditions of the hydrogenation reaction are as follows:

the reaction temperature is 400-450 ℃;

the reaction pressure is 15-26 MPa;

the volume ratio of the hydrogen to the oil is 1000-1500;

the airspeed is 0.3-1.5 h^-1。

11. The method for producing light oil by coal and biomass liquefaction according to claim 1 or 2, wherein the temperature of the fractionation is 340-390 ℃.

12. The method for producing light oil by liquefying coal and biomass according to claim 1 or 2, further comprising the step of collecting a part of distillate oil obtained after the vacuum distillation step and a heavy fraction obtained in the fractionation step, and adding the part of distillate oil and the heavy fraction to the first hydrogenation reaction.

13. The method for producing light oil by coal and biomass liquefaction according to claim 1 or 2, wherein the hydrogenated product further comprises a step of performing a second separation on the hydrogenated product before fractionation to obtain hydrogen, a gas-phase light hydrocarbon and a liquid phase, and the hydrogen is recycled for the first liquefaction reaction, the second liquefaction reaction and the hydrogenation reaction.

14. The method for producing light oil by coal and biomass liquefaction according to claim 1 or 2, wherein the hydrogenation catalyst is at least one of the following catalysts:

1) amorphous iron oxide and/or amorphous iron oxyhydroxide;

2) the amorphous alumina is loaded with active ingredients, the active ingredients are at least one of VIB metal, VIIB metal or VIII metal oxides, and the content of the active ingredients is 10-25 wt%.

15. The method for producing light oil by liquefying coal and biomass according to claim 1 or 2, wherein the coal is low-rank coal.