CN113337310A

CN113337310A - Method for preparing biodiesel by deep processing of biomass residual oil

Info

Publication number: CN113337310A
Application number: CN202110725567.5A
Authority: CN
Inventors: 梁巍
Original assignee: Hainan Yingke Biotechnology Co ltd
Current assignee: Hainan Yingke Biotechnology Co ltd
Priority date: 2021-06-29
Filing date: 2021-06-29
Publication date: 2021-09-03
Anticipated expiration: 2041-06-29
Also published as: CN113337310B

Abstract

The invention relates to a method for deeply processing biomass residual oil; the invention relates to a method for preparing biodiesel by deep processing of biomass residual oil, which adopts a combined process of catalytic pyrolysis of the biomass residual oil, hydrogenation of a pyrolysis heavy oil suspension bed, hydrorefining of pyrolysis light oil and hydrocracking of wax oil to produce the biodiesel; the specific method comprises the following steps: heating biomass residual oil, sending the heated biomass residual oil to a cracking tower, cracking the biomass residual oil in the cracking tower to obtain cracking gas, cracking light oil and cracking heavy oil, wherein the cracking gas is used as device fuel gas, the cracking light oil is sent to a hydrofining part, and the cracking heavy oil is sent to a suspended bed hydrogenation part; separating the hydrogenation product of the suspension bed into light oil of the suspension bed, wax oil of the suspension bed and residual oil of the suspension bed, sending the light oil of the suspension bed to a hydrofining part, and sending the wax oil of the suspension bed to a hydrocracking part; and (3) jointly separating the hydrocracking product and the hydrofining product to obtain gas, biological light oil, biodiesel and tail oil, returning the tail oil to the hydrocracking part for circular cracking, and using the gas as fuel gas of a device.

Description

Method for preparing biodiesel by deep processing of biomass residual oil

Technical Field

The invention relates to a method for deeply processing biomass residual oil, in particular to a method for preparing biodiesel by deeply processing biomass residual oil.

Background

The biodiesel is a renewable fuel resource, has the characteristics of renewability, excellent biodegradability, low sulfur content, low pollutant emission and the like compared with mineral diesel, is real green diesel, and can become an ideal alternative energy source of petroleum fuel.

The residual heavy component residual oil in the production process of the first generation of biodiesel and the residual heavy component residual oil in the extraction process of oleic acid have not been used in an ideal utilization method all the time.

Disclosure of Invention

In order to overcome the defects and shortcomings in the prior art, the invention aims to provide a method for preparing biodiesel by deep processing of biomass residual oil, which has practical economic significance and environmental protection significance for converting the biomass residual oil into the biodiesel with high added value.

The purpose of the invention is realized by the following technical scheme: a method for preparing biodiesel by deep processing of biomass residual oil comprises the following steps:

(1) in the catalytic pyrolysis part, in the presence of a catalyst, under the conditions that the pressure is normal pressure or vacuum and the temperature is 180-350 ℃, the biomass residual oil is pyrolyzed into pyrolysis gas, pyrolysis light oil and pyrolysis heavy oil, wherein the pyrolysis light oil is sent to the hydrofining part, and the pyrolysis heavy oil is sent to the suspension bed hydrogenation part;

(2) in the suspension bed hydrogenation part, the cracked heavy oil is subjected to hydrogenation reaction in the presence of a catalyst under the conditions that the temperature is 200-500 ℃ and the pressure is 3.0-25.0 MPa to generate a suspension bed product consisting of hydrogen, water, conventional gas hydrocarbon and conventional liquid hydrocarbon;

(3) in a suspension bed thermal high-pressure separation part, the suspension bed product is separated into thermal high-pressure gas and thermal high-pressure oil, the thermal high-pressure gas is sent to a hydrofining part, and the thermal high-pressure oil is sent to a heavy oil separation part;

(4) in a heavy oil separation part, separating suspension bed light oil, suspension bed wax oil and suspension bed residual oil from the hot high-fraction oil by a rectification process; sending the light oil of the suspension bed to a hydrofining part, and sending the wax oil of the suspension bed to a hydrocracking part;

(5) in the hydrofining part, the cracking light oil, the thermal high-pressure gas and the suspension bed light oil are merged, and in the presence of a hydrofining catalyst, the mixture is mixed with hydrogen at the temperature of 170-420 ℃, the pressure of 3.0-20.0 MPa, the volume ratio of the hydrogen to the raw oil is 50-3000: 1, and the volume space velocity of the catalyst is 0.05-5h^-1Under the conditions of (1), finishing the hydrofining reaction to produceA hydrorefining reaction product consisting of hydrogen, impurity components, conventional gaseous hydrocarbons, and conventional liquid hydrocarbons;

(6) in the hydrofinishing cold high-pressure separation section, the hydrofinishing reaction product is cooled and separated into: a first cold high-molecular gas mainly composed of hydrogen, a first cold high-molecular oil liquid mainly composed of normal gas hydrocarbon, impurity components and normal liquid hydrocarbon;

(7) in the hydrocracking part, in the presence of a hydrocracking catalyst, the suspension bed wax oil and hydrogen are subjected to reaction at the temperature of 300-500 ℃, the pressure of 3.0-20.0 MPa, the volume ratio of hydrogen to wax oil of 50-3000: 1 and the volume space velocity of the catalyst of 0.05-5h^-1Under the conditions of (1), completing hydrocracking reaction to generate a cracking reaction product consisting of hydrogen, impurity components, conventional gas hydrocarbon and conventional liquid hydrocarbon;

(8) in the hydrocracking cold high pressure separation section, the cracked reaction products are cooled and separated into: a second cold high-molecular gas mainly composed of hydrogen, and a second cold high-molecular oil liquid mainly composed of normal gas hydrocarbon, impurity components and normal liquid hydrocarbon;

(9) in the product separation part, the first cold high-fraction oil liquid and the second cold high-fraction oil liquid are converged and separated into gas, a biological light oil product, a biological diesel oil product and a tail oil component through a rectification process.

Preferably, in the step (6), at least a part of the first cold high-molecular gas is returned to the hydrofining reaction part and/or the suspended bed reaction part to form recycle hydrogen; in the step (8), at least one part of the second cold high-molecular gas is returned to the hydrocracking reaction part to form recycle hydrogen.

Preferably, in the step (1), the pyrolysis gas is discharged from the top of the tower to be used as a plant fuel gas; in the step (4), most of the residual oil in the suspension bed returns to the suspension reaction part, and a small amount of residual oil is discharged; in the step (9), the gas is used as fuel gas of the device, and at least a part of tail oil components are returned to the hydrocracking reaction part for cyclic cracking.

Preferably, in the step (2), the temperature of the suspension bed hydrogenation is 320-450 ℃, the pressure is 8.0-20.0 MPa, and the volume ratio of hydrogen to raw oil is 300-1200: 1.

Preferably, in the step (5), the hydrofining temperature is 260-380 ℃, the pressure is 5.0-15.0 MPa, and the space velocity of the hydrofining catalyst is 0.1-1.0 h^-1The volume ratio of hydrogen to raw oil is 500-2000: 1.

Preferably, in the step (6), in the hydrorefining cold high-pressure separation part, before the hydrorefining reaction product enters the cold high-pressure separator, washing water is injected into the reaction product, the temperature of the hydrorefining reaction product is firstly reduced to be below 200 ℃, and then the hydrorefining reaction product is mixed with the washing water to form the hydrorefining reaction product after water injection; the hydrofining cold high-pressure separation part comprises the steps of cooling and separating a hydrofining reaction product after water injection, wherein the temperature of the hydrofining reaction product after water injection is firstly reduced to 30-70 ℃, and in the process of temperature reduction, the hydrofining reaction product after water injection is separated in a cold high-pressure separator as follows: the first cold high-pressure separation gas mainly comprises hydrogen, the first cold high-pressure separation oil liquid mainly comprises conventional gas hydrocarbon, conventional liquid hydrocarbon and dissolved hydrogen, and the first cold high-pressure separation water liquid mainly comprises water and is dissolved with hydrogen sulfide and ammonia.

Preferably, in the step (7), the hydrocracking temperature is 320-450 ℃, the pressure is 5.0-15.0 MPa, and the space velocity of the catalyst is 0.2-2.0 h^-1The volume ratio of hydrogen to raw oil is 300-1500: 1.

Preferably, in the step (8), in the hydrocracking cold high-pressure separation part, before the hydrocracking reaction product enters the cold high-pressure separator, washing water is injected into the reaction product, the hydrocracking reaction product is generally cooled to below 200 ℃ and then is mixed with the washing water to form the water-injected hydrocracking reaction product; the hydrocracking cold high-pressure separation part comprises the steps of cooling and separating the hydrocracking reaction product after water injection, wherein the temperature of the hydrocracking reaction product after water injection is firstly reduced to 30-70 ℃, and in the temperature reduction process, the hydrocracking reaction product after water injection is separated in a cold high-pressure separator as follows: a second cold high-molecular gas mainly composed of hydrogen, a second cold high-molecular oil liquid mainly composed of conventional gas hydrocarbon, conventional liquid hydrocarbon and dissolved hydrogen, and a second cold high-molecular water liquid mainly composed of water and dissolved with hydrogen sulfide and ammonia.

Preferably, in the step (6), a hot high-pressure separation step is added before a cold high-pressure separation part of hydrorefining, and in the process, a hydrorefining reaction product firstly enters the hot high-pressure separation step with the operation temperature of 180-300 ℃ and is separated into: a first hot high-molecular gas consisting of hydrogen, a first hot high-molecular oil liquid consisting of normal liquid hydrocarbon and dissolved hydrogen; the first hot high-pressure separation gas enters a hydrotreating cold high-pressure separation part, and the first hot high-pressure separation oil liquid is separated into biological light oil and biological diesel oil products in the hot high-pressure separation oil liquid separation part.

Preferably, in the step (8), a hot high-pressure separation step is added before a cold high-pressure separation part of hydrocracking, and in the process, a hydrocracking reaction product firstly enters the hot high-pressure separation step with the operation temperature of 180-300 ℃ and is separated into: a second thermal high-molecular gas consisting of hydrogen gas, a second thermal high-molecular oil liquid consisting of normal liquid hydrocarbon and dissolved hydrogen; and the second hot high-pressure gas enters a hydrocracking cold high-pressure separation part, and the second hot high-pressure oil liquid and the first hot high-pressure oil liquid share the hot high-pressure oil liquid separation part.

The invention has the beneficial effects that: the method adopts a combined process of catalytic pyrolysis of biomass residual oil, hydrogenation of a pyrolysis heavy oil suspension bed, hydrorefining of pyrolysis light oil and hydrocracking of wax oil to produce the biodiesel; the specific method comprises the following steps: heating biomass residual oil, sending the heated biomass residual oil to a cracking tower, cracking the biomass residual oil in the cracking tower to obtain cracking gas, cracking light oil and cracking heavy oil, wherein the cracking gas is used as device fuel gas, the cracking light oil is sent to a hydrofining part, and the cracking heavy oil is sent to a suspended bed hydrogenation part; the hydrogenation product of the suspension bed is separated into light oil of the suspension bed, wax oil of the suspension bed and residual oil of the suspension bed, the light oil of the suspension bed is sent to a hydrofining part, the wax oil of the suspension bed is sent to a hydrocracking part, most of the residual oil of the suspension bed returns to a reaction part of the suspension bed, and a small amount of residual oil is discharged; and (3) jointly separating the hydrocracking product and the hydrofining product to obtain gas, biological light oil, biodiesel and tail oil, returning the tail oil to the hydrocracking part for circular cracking, and using the gas as fuel gas of a device.

The method of the invention can solve the problem of utilization of inferior biological residual oil, is beneficial to increasing the economic benefit and the environmental benefit of enterprises, can promote the use of renewable energy, promote the development and the utilization of low-carbon economy, cyclic economy and new energy, reduce the emission of greenhouse gases such as carbon dioxide and the like, respond to the international carbon neutralization strategy and make great contribution to the alleviation of global warming.

Drawings

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

Detailed Description

For the understanding of those skilled in the art, the present invention will be further described with reference to the following examples and the accompanying fig. 1, and the description of the embodiments is not intended to limit the present invention.

The conventional boiling point of the present invention refers to the vapor-liquid equilibrium temperature of a substance at one atmosphere pressure.

The conventional gaseous hydrocarbon in the present invention refers to hydrocarbon which is gaseous under conventional conditions, and includes methane, ethane, propane and butane.

The conventional liquid hydrocarbon refers to hydrocarbon which is liquid under the conventional conditions, and comprises pentane and hydrocarbon with higher boiling point.

The specific gravity of the present invention refers to the ratio of the density of a liquid at ordinary pressure and 15.6 ℃ to the density of a liquid at ordinary pressure and 15.6 ℃ unless otherwise specified.

The bio-light oil according to the present invention means hydrocarbons having a conventional boiling point of less than 180 ℃.

The biodiesel refers to hydrocarbons with the conventional boiling point of 180-370 ℃.

The impurity components referred to in the present invention refer to the non-hydrocarbon component of the feed as a converted product such as water, ammonia, hydrogen sulfide, etc.

The compositions or concentrations or amounts or yields of the components described herein are weight basis values unless otherwise specified.

The biomass residual oil provided by the invention refers to residual heavy component residual oil in the production process of first-generation biodiesel, residual heavy component residual oil in the extraction process of oleic acid and residual heavy component residual oil in the extraction process of other biological grease.

Referring to fig. 1, the method for preparing biodiesel by deep processing of biomass residual oil of the invention comprises the following steps:

(1) in the catalytic thermal cracking part, the biomass residual oil is heated to 180-350 ℃ by a heating furnace and sent to a cracking tower, the cracking tower can be operated under normal pressure or vacuum condition, the biomass residual oil is subjected to pressure reduction flash evaporation, light oil gas rises to the top of the tower, a heavier liquid phase flows to the bottom of the tower, thermal cracking is performed at the bottom of the tower under continuous high temperature, the cracked gas and the light oil are gasified and rise to the top of the tower, the cracked gas and the light oil are cooled together with the light oil gas at the top of the tower, then the cracked gas and the light oil are sent to a liquid separation tank at the top of the tower, a liquid phase is sent to a hydrofining part, and a gas phase part is sent to a fuel gas pipe network as fuel gas in the device. And continuously discharging the cracked heavy oil at the bottom of the tower to a hydrogenation part of the suspension bed.

The catalytic thermal cracking refers to a reaction process of cracking large molecules of biomass residual oil into small molecules, decarboxylating fatty acid, directly deoxidizing fatty acid and the like under a proper temperature and/or catalyst condition.

(2) In the suspension bed hydrogenation part, the cracked heavy oil is subjected to hydrogenation reaction in the presence of a catalyst under the conditions that the temperature is 200-500 ℃ and the pressure is 3.0-25.0 MPa, so that a suspension bed product consisting of hydrogen, water, conventional gas hydrocarbon and conventional liquid hydrocarbon is generated.

(3) In the suspension bed thermal high-pressure separation part, the suspension bed product is separated into thermal high-pressure separation gas and thermal high-pressure separation oil.

The suspension bed hydrogenation of the invention refers to a hydrogen-consuming reaction process of the cracked residual oil under the condition of hydrogen and catalyst and at a proper temperature, and the lowest reaction depth has the lowest industrial significance: i.e., to provide a suitable hydrogenation feedstock for the hydrofinishing and hydrocracking sections, the process will generally complete the hydrocracking reaction of the macromolecular hydrocarbons, and the process will generally complete the deoxygenation reaction of the majority of the oxygenates.

The operating conditions of the suspension bed hydrogenation reaction part are preferably as follows: the temperature is 320-450 ℃, the pressure is 8.0-20.0 MPa, and the volume ratio of hydrogen to raw oil is 300-1200: 1. The suspended bed thermal high-pressure separation part can be a separate gas-liquid separator or a gas-liquid separation space arranged at the top of a suspended bed reactor, and the reactor is usually a combined reaction system integrating reaction and separation.

(4) In a heavy oil separation part, separating suspension bed light oil, suspension bed wax oil and suspension bed residual oil from the hot high-fraction oil by a rectification process; the light oil of the suspension bed is sent to the hydrofining part, the wax oil of the suspension bed is sent to the hydrocracking part, most of the residual oil of the suspension bed returns to the feed of the suspension bed, and a small amount of residual oil is discharged.

The suspension bed light oil generally refers to a fraction with a boiling point lower than 350 ℃, the suspension bed wax oil generally refers to a fraction with a boiling point of 350-480 ℃, and the suspension bed residual oil generally refers to a fraction with a boiling point higher than 480 ℃.

(5) In the hydrofining part, the cracking light oil, the suspension bed thermal high-pressure gas and the suspension bed light oil are merged, and in the presence of a hydrofining catalyst, the mixture is mixed with hydrogen at the temperature of 170-420 ℃, the pressure of 3.0-20.0 MPa, the volume ratio of the hydrogen to the raw oil is 50-3000: 1, and the volume space velocity of the catalyst is 0.05-5h^-1Under the conditions of (1), finishing the hydrofining reaction to generate a hydrofining reaction product consisting of hydrogen, impurity components, conventional gaseous hydrocarbon and conventional liquid hydrocarbon.

The term hydrorefining as used herein refers to a reaction process of hydrogen consumption by the cracking light oil, the suspension bed heat high-molecular gas and the suspension bed light oil in the presence of hydrogen and a suitable catalyst, and the lowest reaction depth should have the lowest industrial significance: namely qualified biodiesel is produced, and the process generally completes the saturation of all unsaturated bonds in the long-chain structure of the raw oil; generally, the process will remove all of the oxygen, sulfur and nitrogen from the feed oil.

The operating conditions of the hydrorefining reaction part are preferably as follows: the temperature is 260-380 ℃, the pressure is 5.0-15.0 MPa, and the space velocity of the hydrofining catalyst is 0.1-1.0 h^-1And the volume ratio of the hydrogen to the raw oil is 500-2000: 1.

In the hydrofining reaction part, the hydrofining catalyst used can be one or a series combination or a mixed combination of two or more catalysts.

(6) In the cold high pressure separation section of the hydrofinishing, wash water is typically injected into the reaction product before the hydrofinishing reaction product enters the cold high pressure separator. The hydrofining reaction product is generally subjected to temperature reduction to below 200 ℃, and then mixed with washing water to form water injection and hydrofining reaction product.

The hydrofining cold high-pressure separation part comprises the steps of cooling and separating hydrofining reaction products after water injection. The temperature of the hydrorefining reaction product after water injection is usually reduced to 30-70 ℃, and in the process of reducing the temperature, the hydrorefining reaction product after water injection is separated in a cold high-pressure separator into: the first cold high-pressure separation gas mainly comprises hydrogen, the first cold high-pressure separation oil liquid mainly comprises conventional gas hydrocarbon, conventional liquid hydrocarbon and dissolved hydrogen, and the first cold high-pressure separation water liquid mainly comprises water and is dissolved with hydrogen sulfide and ammonia.

As mentioned above, at least a part (usually 80-100%) of the first cold high-molecular gas is returned to the hydrofining reaction part and/or the suspended bed reaction part to form the circulating hydrogen gas, so as to provide the hydrogen amount and the hydrogen concentration necessary for the reaction part.

(7) In a hydrocracking part, in the presence of a hydrocracking catalyst, the suspension bed wax oil and hydrogen are subjected to reaction at the temperature of 300-500 ℃, the pressure of 3.0-20.0 MPa, the volume ratio of hydrogen to wax oil of 50-3000: 1 and the volume space velocity of the catalyst of 0.05-5h^-1Under the conditions of (1), completing the hydrocracking reaction to generate a cracking reaction product consisting of hydrogen, impurity components, conventional gaseous hydrocarbons and conventional liquid hydrocarbons.

The operating conditions of the hydrocracking reaction part are preferably as follows: the temperature is 320-450 ℃, the pressure is 5.0-15.0 MPa, and the space velocity of the catalyst is 0.2-2.0 h^-1And the volume ratio of the hydrogen to the raw oil is 300-1500: 1.

The hydrocracking reaction part has different raw material wax oil properties and different hydrogenation depths, and the change range of the operation conditions is wide and is determined according to specific process conditions.

The hydrocracking catalyst used in the hydrocracking reaction part can be one or a series combination or a mixed combination of two or more catalysts;

in the hydrocracking reaction part, the catalyst airspeed is controlled within a reasonable range, the single-pass conversion rate is controlled within a reasonable range (generally, the single-pass conversion rate is 40-70%, and preferably, the single-pass conversion rate is 50-60%), and the generation of low-carbon hydrocarbons by an over-cracking reaction is reduced as far as possible, so that the yield of the biodiesel is improved.

(8) In the cold high pressure separation section of hydrocracking, wash water is typically injected into the reaction products before the hydrocracking reaction products enter the cold high pressure separator. The hydrocracking reaction product is generally cooled to below 200 ℃, and then mixed with washing water to form the hydrocracking reaction product after water injection.

The hydrocracking cold high-pressure separation part comprises the steps of cooling and separating the hydrocracking reaction products after water injection. The temperature of the water-injected hydrocracking reaction product is usually reduced to 30-70 ℃, and in the temperature reduction process, the water-injected hydrocracking reaction product is separated in a cold high-pressure separator into: a second cold high-molecular gas mainly composed of hydrogen, a second cold high-molecular oil liquid mainly composed of conventional gas hydrocarbon, conventional liquid hydrocarbon and dissolved hydrogen, and a second cold high-molecular water liquid mainly composed of water and dissolved with hydrogen sulfide and ammonia.

As mentioned above, at least a part (usually 80-100%) of the second cold high-molecular gas is returned to the hydrocracking reaction part to form recycle hydrogen, so as to provide the hydrogen amount and hydrogen concentration necessary for the reaction part.

(9) In the product separation part, the steps of separating the biodiesel product, the bio-light oil product and the tail oil component from the first cold high oil separation liquid and the second cold high oil separation liquid are carried out. The first cold high-fraction oil liquid and the second cold high-fraction oil liquid are respectively reduced in pressure and then mixed, the pressure is reduced to 0.5-4.0 MPa generally to form a gas-liquid mixed phase material flow, then the gas-liquid mixed phase material flow is separated through the processes of separation and/or fractionation and the like, the gas-liquid mixed phase material flow is generally separated into gas, biological light oil, biological diesel oil, tail oil and the like, and at least a part of tail oil components are returned to the hydrocracking reaction part for cyclic cracking.

The hydrocracking reaction of the hydrocracking reaction part refers to a hydrogen-consuming cracking process of wax oil in the presence of hydrogen and a proper cracking catalyst, and the lowest reaction depth has the lowest industrial significance: the cracking catalyst has high cracking selectivity to obtain higher diesel oil yield, and can achieve a certain cracking conversion rate (generally 40-70% per pass conversion rate, preferably 50-60% per pass conversion rate).

In order to implement the invention, a thermal high-pressure separation step can be added before the hydrofining refrigeration high-pressure separation part, in the process, the hydrofining reaction product firstly enters the thermal high-pressure separation step with the operation temperature of usually 180-300 ℃, preferably 200-250 ℃ and is separated into: a first hot high-molecular gas consisting of hydrogen, and a first hot high-molecular oil liquid consisting of normal liquid hydrocarbon and dissolved hydrogen. The first hot high-pressure gas enters a hydrotreating cold high-pressure separation part, and the first hot high-pressure oil liquid separates biological light oil and biodiesel products in the hot high-pressure oil liquid separation part (comprising separation and/or fractionation processes). The first hot high-temperature oil-liquid separation part and the product separation part can be partially or completely shared. The process is still within the scope of the present invention, which adds only one separation step, with the advantage of energy saving.

In order to implement the invention, a hot high-pressure separation step can be added before the cold high-pressure separation part of hydrocracking, in the process, the hydrocracking reaction product firstly enters the hot high-pressure separation step with the operation temperature of usually 180-300 ℃, preferably 200-250 ℃ and is separated into: a second hot high-molecular gas consisting of hydrogen gas, and a second hot high-molecular oil liquid consisting of normal liquid hydrocarbon and dissolved hydrogen. The second hot high-pressure gas enters a hydrocracking cold high-pressure separation part, and the second hot high-pressure oil liquid and the first hot high-pressure oil liquid share a hot high-pressure oil liquid separation part (comprising a separation and or fractionation process). The process is still within the scope of the present invention, which adds only one separation step, with the advantage of energy saving.

The above-described embodiments are preferred implementations of the present invention, and the present invention may be implemented in other ways without departing from the spirit of the present invention.

Claims

1. A method for preparing biodiesel by deep processing of biomass residual oil is characterized in that: the method comprises the following steps:

(5) in the hydrofining part, the cracking light oil, the thermal high-pressure gas and the suspension bed light oil are merged, and in the presence of a hydrofining catalyst, the mixture is mixed with hydrogen at the temperature of 170-420 ℃, the pressure of 3.0-20.0 MPa, the volume ratio of the hydrogen to the raw oil is 50-3000: 1, and the volume space velocity of the catalyst is 0.05-5h^-1Under the conditions of (1), finishing the hydrofining reaction to generate a hydrofining reaction product consisting of hydrogen, impurity components, conventional gaseous hydrocarbon and conventional liquid hydrocarbon;

2. The method for preparing biodiesel by deep processing of biomass residual oil according to claim 1, is characterized in that: in the step (6), at least one part of the first cold high-molecular gas returns to the hydrofining reaction part and/or the suspension bed reaction part to form circulating hydrogen; in the step (8), at least one part of the second cold high-molecular gas is returned to the hydrocracking reaction part to form recycle hydrogen.

3. The method for preparing biodiesel by deep processing of biomass residual oil according to claim 1, is characterized in that: in the step (1), the pyrolysis gas is discharged from the top of the tower to be used as fuel gas of a device; in the step (4), most of the residual oil in the suspension bed returns to the suspension reaction part, and a small amount of residual oil is discharged; in the step (9), the gas is used as fuel gas of the device, and at least a part of tail oil components are returned to the hydrocracking reaction part for cyclic cracking.

4. The method for preparing biodiesel by deep processing of biomass residual oil according to claim 1, is characterized in that: in the step (2), the temperature of the suspension bed hydrogenation is 320-450 ℃, the pressure is 8.0-20.0 MPa, and the volume ratio of hydrogen to raw oil is 300-1200: 1.

5. The method for preparing biodiesel by deep processing of biomass residual oil according to claim 1, is characterized in that: in the step (5), the temperature of hydrofining is 260-380 ℃, the pressure is 5.0-15.0 MPa, and the space velocity of the hydrofining catalyst is 0.1-1.0 h^-1The volume ratio of hydrogen to raw oil is 500-2000: 1.

6. The method for preparing biodiesel by deep processing of biomass residual oil according to claim 1, is characterized in that: in the step (6), in the hydrofining cold high-pressure separation part, before the hydrofining reaction product enters the cold high-pressure separator, washing water is injected into the reaction product, the temperature of the hydrofining reaction product is firstly reduced to be below 200 ℃, and then the hydrofining reaction product is mixed with the washing water to form the hydrofining reaction product after water injection; the hydrofining cold high-pressure separation part comprises the steps of cooling and separating a hydrofining reaction product after water injection, wherein the temperature of the hydrofining reaction product after water injection is firstly reduced to 30-70 ℃, and in the process of temperature reduction, the hydrofining reaction product after water injection is separated in a cold high-pressure separator as follows: the first cold high-pressure separation gas mainly comprises hydrogen, the first cold high-pressure separation oil liquid mainly comprises conventional gas hydrocarbon, conventional liquid hydrocarbon and dissolved hydrogen, and the first cold high-pressure separation water liquid mainly comprises water and is dissolved with hydrogen sulfide and ammonia.

7. The method for preparing biodiesel by deep processing of biomass residual oil according to claim 1, is characterized in that: in the step (7), the hydrocracking temperature is 320-450 ℃, the pressure is 5.0-15.0 MPa, and the space velocity of the catalyst is 0.2-2.0 h^-1The volume ratio of hydrogen to raw oil is 300-1500:1。

8. The method for preparing biodiesel by deep processing of biomass residual oil according to claim 1, is characterized in that: in the step (8), in the hydrocracking cold high-pressure separation part, before the hydrocracking reaction product enters the cold high-pressure separator, washing water is injected into the reaction product, the hydrocracking reaction product is generally cooled to below 200 ℃ and then is mixed with the washing water to form the hydrocracking reaction product after water injection; the hydrocracking cold high-pressure separation part comprises the steps of cooling and separating the hydrocracking reaction product after water injection, wherein the temperature of the hydrocracking reaction product after water injection is firstly reduced to 30-70 ℃, and in the temperature reduction process, the hydrocracking reaction product after water injection is separated in a cold high-pressure separator as follows: a second cold high-molecular gas mainly composed of hydrogen, a second cold high-molecular oil liquid mainly composed of conventional gas hydrocarbon, conventional liquid hydrocarbon and dissolved hydrogen, and a second cold high-molecular water liquid mainly composed of water and dissolved with hydrogen sulfide and ammonia.

9. The method for preparing biodiesel by deep processing of biomass residual oil according to claim 1, is characterized in that: in the step (6), a thermal high-pressure separation step is additionally arranged before a hydrofining cold high-pressure separation part, and in the process, a hydrofining reaction product firstly enters the thermal high-pressure separation step with the operation temperature of 180-300 ℃ and is separated into: a first hot high-molecular gas consisting of hydrogen, a first hot high-molecular oil liquid consisting of normal liquid hydrocarbon and dissolved hydrogen; the first hot high-pressure separation gas enters a hydrotreating cold high-pressure separation part, and the first hot high-pressure separation oil liquid is separated into biological light oil and biological diesel oil products in the hot high-pressure separation oil liquid separation part.

10. The method for preparing biodiesel by deep processing of biomass residual oil according to claim 9, is characterized in that: in the step (8), a thermal high-pressure separation step is added before a hydrocracking cold high-pressure separation part, and in the process, a hydrocracking reaction product firstly enters the thermal high-pressure separation step with the operation temperature of 180-300 ℃ and is separated into: a second thermal high-molecular gas consisting of hydrogen gas, a second thermal high-molecular oil liquid consisting of normal liquid hydrocarbon and dissolved hydrogen; and the second hot high-pressure gas enters a hydrocracking cold high-pressure separation part, and the second hot high-pressure oil liquid and the first hot high-pressure oil liquid share the hot high-pressure oil liquid separation part.