CN117089361A

CN117089361A - Preparation system and preparation method of refined asphalt

Info

Publication number: CN117089361A
Application number: CN202311181294.8A
Authority: CN
Inventors: 赵鹏; 刘敏; 黄澎; 寇丽红; 马博文; 王昊; 李文博; 胡迪
Original assignee: CCTEG China Coal Research Institute
Current assignee: CCTEG China Coal Research Institute
Priority date: 2023-09-13
Filing date: 2023-09-13
Publication date: 2023-11-21

Abstract

The invention relates to the technical field of refined asphalt preparation and discloses a preparation system and a preparation method of refined asphalt, wherein the system comprises the following steps: the preparation tank, the centrifuge, the dead-end filter, the ceramic membrane filter, the first flash tower and the second flash tower are sequentially connected, and a filtrate outlet of the ceramic membrane filter is connected with the first flash tower to obtain high-grade refined asphalt, and a concentrated solution outlet of the ceramic membrane filter is connected with the second flash tower to obtain medium-grade refined asphalt. The invention can prepare the ultra-low ash refined asphalt with the ash concentration less than 100ppm, improves the preparation efficiency and yield of the refined asphalt, realizes continuous, stable and long-period operation, and realizes diversified grades of the prepared refined asphalt products.

Description

Preparation system and preparation method of refined asphalt

Technical Field

The invention relates to the technical field of refined asphalt preparation, in particular to a preparation system and a preparation method of refined asphalt.

Background

The key technology of the direct liquefaction of the megaton coal is mastered in China, but the technology of the efficient recycling of the coal liquefaction residues has no large-scale breakthrough. The yield of coal liquefaction residues is typically 30% of the feed coal. It has high carbon, ash and sulfur properties and is composed of heavy oil, liquefied intermediate product, unconverted coal and minerals.

The appearance of the coal liquefaction residue is similar to asphalt, the coal liquefaction residue is a flaky solid with black luster, the coal liquefaction residue is crisp and fragile, the sulfur element content in the coal liquefaction residue is high, the sulfur is enriched in the coal liquefaction residue due to the use of a sulfur auxiliary agent in the liquefaction process, the existence form of the sulfur in the coal liquefaction residue is mostly inorganic sulfur, the nitrogen content of the coal liquefaction residue is 0.84%, and the ash content is 16.52%, and mainly comprises minerals in coal and residual liquefaction catalyst.

Traditional gasification, coking and combustion do not represent a high value-added utilization potential for liquefaction residues. The preparation of high-end carbon materials from coal liquefaction residues is a hot spot in the research of the current direct coal liquefaction technology field, and the key point of the realization of the process is high-efficiency deep deashing of the residues. Because the residue has the characteristics of small solid particle size, very high viscosity, small density difference between liquid phase and granular solid, and the like, the difficulty of removing inorganic ash in the liquefied asphalt is increased. Therefore, the high-efficiency deep deashing technology is developed aiming at the fluid characteristics and physical property differences of the liquefied asphalt in an extraction system, the technical bottleneck of preparing high-end carbon materials by the liquefied asphalt is broken through, the development of the whole process chain is completed, and the high-efficiency deep deashing technology is also an important component of the development of the coal liquefaction process technology and the extension of an industrial chain.

In the prior art, coal tar washing oil is used as an extracting agent, centrifugal separation and standing sedimentation are combined, and a decompression distillation solvent recovery method is adopted to obtain coal liquefied asphalt products with high, medium and early three grades. However, the method has low standing sedimentation efficiency, can not efficiently provide materials for downstream units, and severely restricts the continuity of the residue deashing refining process.

Disclosure of Invention

The present invention aims to solve at least one of the technical problems in the related art to some extent. The inventor realizes that ash content in the extract liquid after the coal liquefaction residue is centrifuged is mainly tiny particles with the particle size of less than 100um, wherein the ratio of the particle size of less than 20um is about 60%, the particles are in the shape of tiny dispersed irregular blocks, the aggregation adsorption effect is weak, and the high viscosity system of the coking wash oil and the coal liquefaction residue extract liquid prevents the movement of the particles, so that the sedimentation speed is greatly slowed down. It is difficult to effectively remove these particles by settling, it often takes 48 hours or more, and the yield is not high due to the presence of the settled layer.

Therefore, the embodiment of the invention provides a preparation system and a preparation method of refined asphalt, which can prepare ultra-low ash refined asphalt with ash concentration less than 100ppm, improve the preparation efficiency and yield of the refined asphalt, realize continuous, stable and long-period operation, and realize the diversification of the prepared refined asphalt product grade.

In one aspect, an embodiment of the present application provides a system for preparing refined asphalt, including: the device comprises a preparation tank, a centrifuge, a dead-end filter, a ceramic membrane filter, a first flash tower and a second flash tower, wherein the preparation tank is used for adding an extractant and coal liquefaction residues and mixing and pulping; the centrifugal machine is provided with a feed inlet, an extract liquid discharge port and a raffinate discharge port, and the feed inlet is connected with the preparation tank; the dead-end filter is connected with the extract discharge port of the centrifuge so as to introduce extract into the dead-end filter for filtering, and a first filtrate is obtained; the ceramic membrane filter is provided with a filtrate inlet, a second filtrate outlet and a concentrated solution outlet, the filtrate inlet is connected with the dead-end filter, so that the first filtrate is led into the ceramic membrane filter for cross-flow filtration to obtain second filtrate and concentrated solution, the second filtrate is discharged from the second filtrate outlet, and the concentrated solution is discharged from the concentrated solution outlet; the first flash tower is connected with the second filtrate outlet of the ceramic membrane filter so as to flash the second filtrate to obtain high-grade refined asphalt; and the second flash tower is connected with the concentrated solution outlet of the ceramic membrane filter so as to flash the concentrated solution to obtain the medium-grade refined asphalt.

Aiming at the unique structural composition of the coal liquefaction residues, the application creatively uses a ceramic membrane ultrafiltration technology for the coal liquefaction residues extraction system according to the physical characteristics and the solubility of an extractant mixed system, is coupled with a centrifugal separation and dead-end filtration technology and is perfect and optimized in applicability, so as to prepare the ultra-low ash (< 100 ppm) refined asphalt which is used for high-end carbon material raw materials, realize the ultra-low ash asphalt refining technology for preparing the liquefaction residues, and prolong the continuous, stable and safe operation period.

The application adjusts and optimizes the process regulation strategy of the coal liquefaction residue dissolution system in the centrifugation and traditional dead-end filtration process, primarily removes large-particle solids by centrifugation, removes most small-particle solids by dead-end filtration, further removes the residual small-particle solids by ceramic membrane filtration, uses the classification ash removal refining technology in the coal liquefaction residue dissolution ash removal refining process, fully plays the roles of thermal dissolution and upstream and downstream tight coupling of various separation technologies, realizes the complementary advantages of various separation technologies, forms a complete coal liquefaction residue ash removal refining technology chain, and provides good technical support for the preparation of ultra-low ash refined asphalt for high-end carbon material raw materials.

The ceramic membrane filter adopts the inorganic ceramic membrane nanoscale filter element, has narrow pore size distribution and extremely high separation precision, can achieve nanoscale filtration, has stable filtration effect, and has good high temperature resistance and high mechanical strength. In addition, a cross-flow filtration mode different from the traditional dead-end filtration mode is adopted, based on the sieving effect of a porous ceramic medium, filtrate and mother liquor are led to permeate through a membrane outwards in the vertical direction under the driving of pressure, a proper flow rate is adjusted, micron and submicron suspended matters are intercepted by the ceramic membrane and enter concentrated solution, a filter cake layer is not formed on the surface of the membrane, the fluid purification is realized, and the continuous operation period is prolonged.

In some embodiments, the first flash column has a first inlet connected to the second filtrate outlet of the ceramic membrane filter, a first outlet for discharging the flash separated extractant, and a second outlet for discharging the separated higher refined asphalt;

the second flash tower is provided with a second inlet, a third outlet and a fourth outlet, wherein the second inlet is connected with the first filtrate outlet of the dead-end filter, the third inlet is connected with the concentrated solution outlet of the ceramic membrane filter, the third outlet is used for discharging the extractant separated by flash evaporation, and the fourth outlet is used for discharging the separated medium-grade refined asphalt;

The first filtrate outlet of the dead-end filter is connected with the second inlet of the second flash distillation tower and the filtrate inlet of the ceramic membrane filter through pipelines respectively, the first filtrate outlet of the dead-end filter is connected with a first control valve on a pipeline of the ceramic membrane filter, and the first filtrate outlet of the dead-end filter is connected with a second control valve on a pipeline connected with the second flash distillation tower.

The application can produce refined asphalt with different grades by switching on and off the first control valve and the second control valve according to the price of the carbon material product and the market supply and demand, and adjust the yield of the refined asphalt with different grades. If the high-grade refined asphalt is not produced, only the common dead-end filter filtrate is required to flash evaporation; if the high-grade refined asphalt is produced, the common dead-end filter filtrate and the ceramic membrane filter concentrated solution are mixed and then flash-evaporated, and the ceramic membrane filter filtrate is flash-evaporated.

In some embodiments, the dead-end filter comprises a first dead-end filter and a second dead-end filter, the extract discharge port of the centrifuge is connected with the first dead-end filter and the second dead-end filter through pipelines respectively, and a control valve is connected with the pipelines connecting the first dead-end filter and the second dead-end filter respectively, so that any one of the first dead-end filter and the second dead-end filter is in an operating state at any time point.

The application adopts two or more dead-end filters, when one of the dead-end filters needs to clean filter residues, the other dead-end filter starts to operate, so that the whole process is ensured to continuously operate.

In some embodiments, the dead-end filter is connected with a forward blowing pipeline and a reverse blowing pipeline, the dead-end filter has an inlet, a first filtrate outlet and a filter cake outlet, the inlet of the dead-end filter is positioned at the lower part of the dead-end filter, the first filtrate outlet is positioned at the upper part of the dead-end filter, the filter cake outlet is positioned at the bottom of the dead-end filter, the forward blowing pipeline is connected with the inlet of the dead-end filter, and the reverse blowing pipeline is connected with the first filtrate outlet of the dead-end filter.

The application can pass the filtrate in the filter residue or the filter cake through the filter element of the dead-end filter through forward blowing, thereby playing a role in assisting in filtration on one hand, and reducing the viscosity of the filter residue or the filter cake on the other hand, so that the filter residue or the filter cake is more easily separated from the filter element. The filter residue or the filter cake after forward blowing can be easily blown off through reverse blowing.

The inventor realizes that the difficulty of adopting the dead-end filtration technology is that the high-viscosity material formed by the coal liquefaction residues and the extracting agent is extremely easy to be adsorbed on the surface of the filter element to increase the filtration resistance, so that the filter element cannot be used for high-efficiency filtration and deashing, only frequent back flushing cleaning is realized, the cleaning difficulty is high due to the high-viscosity material, and the filter residues or filter cakes are difficult to blow off only by adopting a conventional back flushing mode, so that the continuous working efficiency is greatly reduced. The application solves the problem by combining forward blowing and backward blowing, improves the recoil cleaning efficiency and greatly improves the continuous working efficiency.

In some embodiments, a dryer is also included, the dryer having a first filter cake inlet connected to the raffinate outlet of the centrifuge, a second filter cake inlet connected to the filter cake outlet of the dead-end filter, a dry filter cake outlet, and an extractant outlet.

The application adopts the drier to dry the filter residue or filter cake produced by the centrifugal machine and the dead-end filter, and recovers the dry filter residue and the extractant for reuse.

In some embodiments, heating devices are disposed within the compounding tank, the centrifuge, the dead end filter, and the ceramic membrane filter.

When the extractant in the raw materials adopts heavy extractant, all need to carry out heating operation in preparing jar, centrifuge, dead end filter and ceramic membrane filter, make heavy oil, asphaltene and the former asphaltene in the coal liquefaction residue more dissolve into the extractant, accelerate the dissolution, improve the solubility.

In some embodiments, the centrifuge is a decanter centrifuge, the separation line speed is 80-160m/s, and the separation temperature is from ambient temperature to 150 ℃.

The horizontal decanter centrifuge is continuous feeding and continuous discharging equipment, and is very suitable for large-scale and long-period continuous operation. Increasing the horizontal decanter centrifuge linear velocity and separation temperature can increase the separation efficiency of the extract and the raffinate, which is beneficial to the reduction of the solid content in the extract, however, too high centrifuge linear velocity and separation temperature both lead to increased energy consumption. Therefore, the separation line speed of the horizontal decanter centrifuge is limited to 80-160m/s, different separation temperatures are adopted for a heavy extraction system and a light extraction system, namely, the normal temperature is between 150 ℃, and the solid content in the final extract can reach less than 1-2%.

In another aspect, the embodiment of the application provides a method for preparing refined asphalt, which uses the preparation system to prepare asphalt, and comprises the following steps:

adding an extractant and coal liquefaction residues into the preparation tank to mix and pulp so as to obtain slurry;

introducing the slurry into the centrifugal machine for solid-liquid separation to obtain an extract;

introducing the extract into the dead-end filter for filtering to obtain a first filtrate;

introducing the first filtrate into the ceramic membrane filter for cross-flow filtration to obtain second filtrate and concentrated solution;

introducing the second filtrate into the first flash tower for flash evaporation to obtain high-grade refined asphalt; and introducing the concentrated solution into the second flash tower for flash evaporation to obtain the medium-grade refined asphalt.

The application adopts the centrifugal separation-traditional dead-end filtration-ceramic membrane ultrafiltration coupling process technology, has the characteristics of closed operation, safety, environmental protection, strong pollution-receiving capability, high automation degree, flexible process and diversified products of refined asphalt product grades, is suitable for special working conditions of a high ash content system for extracting coal liquefaction residues, a high-viscosity system for extracting coal liquefaction residues, ultrahigh filtration precision and a high-temperature process environment, and the prepared ultralow ash refined asphalt is a high-quality raw material of high-end carbon materials (high-performance asphalt-based carbon fibers, foam carbon, lithium ion battery cathode materials, needle coke and the like).

In some embodiments, the first filtrate outlet of the dead-end filter is connected to the second inlet of the second flash column and the filtrate inlet of the ceramic membrane filter respectively by a pipeline, a first control valve is connected to the pipeline of the first filtrate outlet of the dead-end filter and the ceramic membrane filter, and a second control valve is connected to the pipeline of the first filtrate outlet of the dead-end filter and the second flash column;

communicating the first control valve with the second control valve, introducing one part of the first filtrate into the second flash evaporation tower, introducing the other part of the first filtrate into the ceramic membrane filter for cross-flow filtration to obtain the second filtrate and the concentrated solution, introducing the second filtrate into the first flash evaporation tower for flash evaporation to obtain high-grade refined asphalt, introducing the concentrated solution into the second flash evaporation tower for flash evaporation, and mixing the concentrated solution with the first filtrate to obtain medium-grade refined asphalt;

or, only the second control valve is communicated, and the first filtrate is introduced into the second flash tower for flash evaporation to obtain medium-grade refined asphalt;

or, only the first control valve is communicated, the first filtrate is introduced into the ceramic membrane filter for cross-flow filtration to obtain the second filtrate and the concentrated solution, the second filtrate is introduced into the first flash evaporation tower for flash evaporation to obtain high-grade refined asphalt, and the concentrated solution is introduced into the second flash evaporation tower for flash evaporation to obtain medium-grade refined asphalt.

The application can flexibly adjust the yield of the deashing refined asphalt with different grades according to the price of the carbon material product and the market supply and demand.

In some embodiments, when the pressure differential between the inlet of the dead-end filter and the first filtrate outlet is greater than 1.5kgf/cm ² Stopping feeding, introducing purge gas into the dead-end filter through the inlet of the dead-end filter, and starting a positive blowing mode to assist filtrate to be discharged from the first filtrate outlet, wherein the positive blowing pressure is 3-5kgf/cm ² ；

Wherein if the pressure difference between the inlet of the dead-end filter and the first filtrate outlet is less than 1.5kgf/cm ² Stopping the forward blowing, and continuing to introduce the extraction liquid into the dead-end filter;

if the pressure difference between the inlet of the dead-end filter and the first filtrate outlet is still greater than 1.5kgf/cm ² Stopping the forward blowing, introducing purge gas into the dead-end filter through the first filtrate outlet, and starting a back blowing mode, wherein the pressure of the back blowing gas is 3-5kgf/cm ² Until the pressure difference between the inlet of the dead-end filter and the first filtrate outlet is less than 1.5kgf/cm ² Stopping back blowing, and continuing to introduce the extraction liquid into the dead-end filter.

Drawings

The foregoing and/or additional aspects and advantages of the present application will become apparent and may be better understood from the following description of embodiments with reference to the accompanying drawings,

Wherein:

FIG. 1 is a schematic diagram of a system for preparing refined asphalt in an embodiment of the present application;

reference numerals:

1-a preparation tank; 2-a metering tank; 3-a centrifuge; 4-a first dead-end filter; 5-a second dead-end filter; 6-a filtrate storage tank; 7-a second flash column; 8-a first flash column; 9-ceramic membrane filter; 10-a dryer; 11-a first control valve; 12-a second control valve.

Detailed Description

Reference will now be made in detail to embodiments of the present application, examples of which are illustrated in the accompanying drawings. The embodiments described below by referring to the drawings are illustrative and intended to explain the present application and should not be construed as limiting the application.

The following describes a system and a method for producing refined asphalt according to an embodiment of the present application with reference to the accompanying drawings.

As shown in fig. 1, an embodiment of the present application provides a system for preparing refined asphalt, including: the preparation tank 1, the centrifuge 3, the dead-end filter, the ceramic membrane filter 9, the first flash tower 8 and the second flash tower 7, wherein the preparation tank 1 is used for adding an extractant and coal liquefaction residues and mixing and pulping; the centrifuge 3 is provided with a feed inlet, an extract discharge port and a raffinate discharge port, and the feed inlet is connected with the preparation tank 1; the dead-end filter is connected with an extract discharge port of the centrifuge 3 so as to introduce the extract into the dead-end filter for filtering, thereby obtaining a first filtrate; the ceramic membrane filter 9 is provided with a filtrate inlet, a second filtrate outlet and a concentrated solution outlet, wherein the filtrate inlet is connected with the dead-end filter so as to lead the first filtrate into the ceramic membrane filter 9 for cross-flow filtration to obtain second filtrate and concentrated solution, the second filtrate is discharged from the second filtrate outlet, and the concentrated solution is discharged from the concentrated solution outlet; the first flash tower 8 is connected with a second filtrate outlet of the ceramic membrane filter 9 so as to flash-evaporate the second filtrate to obtain high-grade refined asphalt; the second flash tower 7 is connected with a concentrated solution outlet of the ceramic membrane filter 9 to flash-evaporate the concentrated solution to obtain the medium-grade refined asphalt.

The ceramic membrane filter 9 adopts an inorganic ceramic membrane nanoscale filter element, has narrow pore size distribution and extremely high separation precision, can achieve nanoscale filtration, has stable filtration effect, and has good high temperature resistance and high mechanical strength. In addition, a cross-flow filtration mode different from the traditional dead-end filtration mode is adopted, based on the sieving effect of a porous ceramic medium, filtrate and mother liquor are led to permeate through a membrane outwards in the vertical direction under the driving of pressure, a proper flow rate is adjusted, micron and submicron suspended matters are intercepted by the ceramic membrane and enter concentrated solution, a filter cake layer is not formed on the surface of the membrane, the fluid purification is realized, and the continuous operation period is prolonged.

Further, a stirring device is arranged in the preparation tank 1 and used for uniformly mixing materials and accelerating the extraction reaction in the preparation tank 1. The bottom of the preparation tank 1 is connected with the top of the preparation tank 1 through a circulating pipeline, a circulating pump is arranged on the circulating pipeline, slurry at the bottom of the preparation tank 1 is conveyed to the top of the preparation tank 1 through the circulating pump, and the slurry is circularly stirred, so that stirring and reaction are more sufficient. The circulating pipeline is connected with the discharging pipe through a three-way valve. When stirring in the preparation tank 1 is finished, the three-way valve is switched to the direction of the discharge pipe, the discharge pipe is communicated, slurry is pumped into the discharge pipe from the bottom of the preparation tank 1 through the circulating pump, and the discharge pipe is connected with the centrifugal machine 3. After the slurry is pumped into the centrifuge 3, the three-way valve is switched back to the circulation state.

In some embodiments, a metering tank 2 is connected between the discharge pipe of the preparation tank 1 and the centrifugal machine 3, and the metering tank 2 has the function of feeding and metering, so that slurry can be continuously and stably pumped into the centrifugal machine 3. When the stirring in the preparation tank 1 is finished, the preparation tank 1 pumps the slurry into the metering tank 2, and the slurry in the metering tank 2 is pumped into the centrifuge 3 after being metered.

Further, the metering tank 2 is also provided with a stirring device and a circulation pipeline, and the stirring device and the circulation pipeline of the preparation tank 1 are the same, and are not described in detail herein.

And a pump body is connected to a pipeline between the extraction liquid discharge port of the centrifugal machine 3 and the dead-end filter, and the extraction liquid is conveyed into the dead-end filter through the pump body.

In some embodiments, the first flash column 8 has a first inlet connected to the second filtrate outlet of the ceramic membrane filter 9, a first outlet for discharging the extractant separated by the flash distillation, and a second outlet for discharging the separated high-grade refined asphalt;

the second flash tower 7 is provided with a second inlet, a third outlet and a fourth outlet, wherein the second inlet is connected with the first filtrate outlet of the dead-end filter, the third inlet is connected with the concentrated solution outlet of the ceramic membrane filter 9, the third outlet is used for discharging the extractant separated by flash evaporation, and the fourth outlet is used for discharging the separated medium-grade refined asphalt;

The first filtrate outlet of the dead-end filter is connected with the second inlet of the second flash tower 7 and the filtrate inlet of the ceramic membrane filter 9 through pipelines respectively, the first filtrate outlet of the dead-end filter is connected with a first control valve 11 on the pipeline of the ceramic membrane filter 9, and the first filtrate outlet of the dead-end filter is connected with a second control valve 12 on the pipeline connected with the second flash tower 7.

The application can produce different grades of refined asphalt by switching on and off the first control valve 11 and the second control valve 12 according to the price of the carbon material product and the market supply and demand, and adjust the yield of the different grades of refined asphalt. If the high-grade refined asphalt is not produced, only the common dead-end filter filtrate is required to flash evaporation; if the high-grade refined asphalt is produced, the common dead-end filter filtrate and the concentrated solution of the ceramic membrane filter 9 are mixed and then flash-evaporated, and the filtrate of the ceramic membrane filter 9 is flash-evaporated.

Further, the first outlet is located at the top of the second flash column 7, and the second outlet is located at the bottom of the second flash column 7. The third outlet is positioned at the top of the second flash tower 7, and the fourth outlet is positioned at the bottom of the second flash tower 7.

In some embodiments, the dead-end filters comprise a first dead-end filter 4 and a second dead-end filter 5, and the extract discharge port of the centrifuge 3 is connected to the first dead-end filter 4 and the second dead-end filter 5 through a pipeline, respectively, and a control valve is connected to the pipeline connecting the first dead-end filter 4 and the second dead-end filter 5, respectively, so that at any point in time, any one of the first dead-end filter 4 and the second dead-end filter 5 is in an operating state.

It should be noted that if the dead-end filter is frequently switched, the loss of manpower and material resources is also caused, so that as few dead-end filters as possible are required to be switched, and the switching period of the dead-end filter is controlled. By adopting the technical scheme of the application, the switching period can be controlled to be more than 40 days.

In some embodiments, a dead-end filter is connected with a forward blowing line and a reverse blowing line, the dead-end filter having an inlet, a first filtrate outlet and a filter cake outlet, the inlet of the dead-end filter being located in a lower portion of the dead-end filter, the first filtrate outlet being located in an upper portion of the dead-end filter, the filter cake outlet being located in a bottom portion of the dead-end filter, the forward blowing line being connected to the inlet of the dead-end filter, the reverse blowing line being connected to the first filtrate outlet of the dead-end filter.

In some embodiments, the purge line also connects the formulation tank 1 and the metering tank 2 for pressurizing and purging the formulation tank 1 and the metering tank 2.

In some specific embodiments, a filtrate tank 6 is further included, the filtrate tank 6 being connected to the first filtrate outlet of the dead-end filter for storing filtrate after dead-end filtration. The liquid outlet of the filtrate storage tank 6 is respectively connected with the second flash tower 7 and the ceramic membrane filter 9 through pipelines, and the first control valve 11 and the second control valve 12 are arranged on the pipelines.

Further, a stirring device is arranged in the filtrate storage tank 6 and is used for stirring the filtrate.

In some specific embodiments, two or more ceramic membrane filters 9 are provided, and when one ceramic membrane filter 9 needs to clean filter residues, the other ceramic membrane filter 9 starts to operate, so that the whole process is ensured to continuously operate.

It should be noted that if the ceramic membrane filter 9 is frequently switched, the loss of manpower and material resources is also caused, so that it is necessary to switch the ceramic membrane filter 9 as little as possible and control the switching cycle of the ceramic membrane filter 9. By adopting the technical scheme of the application, the switching period can be controlled to be more than 40 days.

Specifically, the cleaning of the ceramic membrane filter 9 is divided into the following two modes:

(1) High flow rate extractant rinse

The cleaning liquid can be one or more of heavy extractant, light extractant, chemical reagent and industrial solvent for coal liquefaction residue, the flushing temperature is determined according to the boiling point of the extractant, the flushing temperature of the heavy extractant is 60-150 ℃, and the light extractant does not need heating (such as tetrahydrofuran).

During flushing, the second filtrate outlet of the ceramic membrane filter 9 is closed (controlled by a valve), the filtrate inlet and the concentrate outlet are opened (controlled by a valve), and the surface of the ceramic membrane is flushed with a high flow rate (> 5 m/s) of the extractant to remove soft impurities.

(2) Backwash method

The operation is reverse to the filtering direction, the cleaning liquid can be one or more of heavy extractant, light extractant, chemical reagent and industrial solvent for coal liquefaction residue, the backwashing temperature is determined according to the boiling point of the extractant, the backwashing temperature of the heavy extractant is 60-150 ℃, and the light extractant does not need to be heated (such as tetrahydrofuran).

During backwashing, the filtrate inlet of the ceramic membrane filter 9 is closed (controlled by a valve), the second filtrate outlet and the concentrated solution outlet are opened (controlled by the valve), and the extractant enters from the second filtrate outlet and flows to the concentrated solution outlet to wash out membrane pore channels and membrane surface pollutants.

In some embodiments, a dryer 10 is also included, the dryer 10 having a first filter cake inlet connected to the raffinate outlet of the centrifuge 3, a second filter cake inlet connected to the filter cake outlet of the dead-end filter, a dry filter cake outlet, and an extractant outlet.

The application adopts the dryer 10 to carry out drying treatment on filter residues or filter cakes generated by the centrifugal machine 3 and the dead-end filter, and recovers the dry filter residues and the extractant for recycling.

After centrifugation, a portion of the extractant remains in the raffinate residue and a majority in the extract. A portion of the extractant is also retained in the filter residue or cake in the dead-end filter. The dry residue and extractant may be recovered by drying the raffinate, residue or filter cake with the dryer 10.

The centrifugal filter residue and the filter residue of the dead-end filter which is discharged periodically contain 20-30% of extractant, the extractant remained in the filter residue is recovered by adopting heating and drying (such as film drying or vacuum drying or steam stripping, etc.), the drying temperature is 200-300 ℃, the drying time is 1-5h, the recovered extractant can be mixed with the extractant recovered by flash evaporation and then is used for residue pulping in the preparation tank 1, and the recovered dry filter residue can be used as fuel or gasification raw material.

In some embodiments, heating means are provided within the formulation tank 1, centrifuge 3, dead end filter and ceramic membrane filter 9.

When the extractant in the raw materials adopts heavy extractant, all need to carry out heating operation in the preparation tank 1, the centrifuge 3, the dead end filter and the ceramic membrane filter 9, so that heavy oil, asphaltene and pre-asphaltene in the coal liquefaction residues are more dissolved into the extractant, the dissolution is accelerated, and the solubility is improved.

Further, the heating device is one or more of an oil bath heating device, a steam heating device and an electric heating device, and can be other heating devices in the prior art.

In some embodiments, the centrifuge 3 may alternatively be a cyclone separator, a filter press separator, or the like.

Preferably, the centrifuge 3 is a decanter centrifuge, the separation line speed is 80-160m/s, and the separation temperature is normal temperature-150 ℃.

The room temperature may be 25℃or 20℃or any temperature therebetween.

In the system of the application, the control valves are arranged on the corresponding pipelines according to the requirements, and the description is omitted here.

s1, adding an extractant and coal liquefaction residues into a preparation tank 1 to mix and pulp so as to obtain slurry;

s2, introducing the slurry into a centrifugal machine 3 for solid-liquid separation to obtain an extract;

s3, introducing the extract into a dead-end filter for filtering to obtain a first filtrate;

s4, introducing the first filtrate into a ceramic membrane filter 9 for cross-flow filtration to obtain a second filtrate and a concentrated solution;

s5, introducing the second filtrate into a first flash tower 8 for flash evaporation to obtain high-grade refined asphalt; and introducing the concentrated solution into a second flash tower 7 for flash evaporation to obtain the medium-grade refined asphalt.

In some specific embodiments, in step S1, the coal liquefaction residue is milled to a particle size <2mm for use, which shortens the dissolution time and improves the dissolution efficiency. The extractant is chemical reagent, industrial solvent or mixture of chemical reagent and industrial solvent, the chemical reagent is one or more of tetrahydrofuran, N-methyl pyrrolidone (NMP) and tetrahydronaphthalene, and the industrial solvent is one or more of coking wash oil, coking light oil and liquefied medium oil. The extractant is divided into a light extractant and a heavy extractant, wherein the heavy extractant is only coked wash oil, and the light extractant is the other heavy extractant.

(1) When a heavy extractant is used, the dissolution system in formulation tank 1 is a heavy dissolution system.

Adding heavy extractant into preparation tank1, starting a circulating pump and a stirring device of the preparation tank 1, circulating slurry for 10-20 times/h, wherein the stirring speed is 120-280rpm, adding powdery coal liquefaction residues when the temperature in the preparation tank 1 is raised to 60-100 ℃, and the mass ratio of the extractant to the coal liquefaction residues is 2:1-5:1, beginning pulping, and introducing N after the addition of coal liquefaction residues ₂ Regulating the pressure to 0.1-0.5MPa, regulating the stirring speed to 200-350rpm, continuously heating the oil bath of the preparation tank 1 to 80-160 ℃, keeping the temperature for 30-90min, switching the three-way valve to the direction of the metering tank 2, pumping the slurry into the metering tank 2 once, switching the three-way valve back to a circulating state, and continuously and stably pumping the slurry into the centrifugal machine 3 by the metering tank 2.

(2) When a light extractant is used, the dissolution system in the formulation tank 1 is a light dissolution system.

Adding a light extractant into a preparation tank 1, starting a circulating pump and a stirring device of the preparation tank 1, circulating slurry for 10-20 times/h, stirring at a speed of 120-280rpm, adding powdery coal liquefaction residues, and the mass ratio of the extractant to the coal liquefaction residues is 2:1-5:1, beginning pulping, and introducing N after the addition of coal liquefaction residues ₂ The pressure is regulated to 0.1-0.5MPa, the stirring speed is regulated to 200-350rpm, the three-way valve is switched to the direction of the metering tank 2 after stirring for 30-90min, the three-way valve is switched back to the circulating state after the slurry is pumped into the metering tank 2 once, and the metering tank 2 continuously and stably pumps the slurry into the centrifugal machine 3.

When the extractant is a mixture of coker wash oil and other light extractant, it is necessary to determine whether the dissolution system in the formulation tank 1 needs to be heated according to the mass ratio of coker wash oil to light extractant. If the coker wash oil is small, no heating of the dissolution system is required. The mixing with different light extractant is different, and will not be described here. It will be appreciated that all of the dissolution system may be heated, but in some cases heating may not be as effective as not heating, and heating may not be required from the standpoint of energy consumption.

In some specific embodiments, in step S3, before the dead-end filter is introduced into the extraction liquid discharged from the centrifuge 3, the dead-end filter needs to be preheated to 80-160 ℃ and constant for the heavy extraction system, and no preheating is needed for the light extraction system.

In some specific embodiments, the dead-end filter has a pressure resistance of up to 1.0MPa and a temperature resistance of up to 200deg.C, and a filtration pore size of 0.5-5 μm.

In some specific embodiments, in step S4, before the filtrate is introduced into the ceramic membrane filter 9, the ceramic membrane filter 9 needs to be preheated to 80-160 ℃ (preheating temperature is set according to the boiling point of the extractant) and constant for the heavy extraction system, and the preheating mode may be oil bath jacket heating, electric heating, internal circulation heating of the hot extractant, etc., and preheating is not needed for the light extraction system (such as tetrahydrofuran).

In some specific embodiments, in step S4, part of the concentrated solution discharged from the ceramic membrane filter 9 is returned to the inlet of the ceramic membrane filter 9, mixed with the first filtrate, and then enters the ceramic membrane filter 9 for filtration, so that the concentrated solution is filtered for a second time, and the filtration is more sufficient. Corresponding piping is not shown in the figures.

The flow rate of the material in the ceramic membrane filter 9 is 3-5m/s and 2-4Kgf/cm ² Under the drive of pressure, the filtrate is formed by outwards penetrating through the ceramic membrane along the direction perpendicular to the material flow, the liquid filtrate amount is 30-60% of the liquid filtrate amount of the dead-end filter entering the ceramic membrane filter 9, insoluble micron-sized and submicron-sized suspended matters and macromolecular substances are intercepted by the membrane to form a concentrated liquid discharge, and the discharge amount is 40-70% of the liquid filtrate amount of the dead-end filter entering the ceramic membrane filter 9.

The ceramic membrane filter 9 has the highest pressure resistance of 1.0MPa, the temperature resistance of 180 ℃ (limited by a sealing element), the acid and alkali resistance range of pH=1-14, the heating rate is not more than 10 ℃/min, and the severe temperature difference impact is avoided. The filter element adopts a precise ceramic filter material, the porosity is 35-45%, the filter pore diameter is 10-50 nm, the nano-scale pore structure is smaller than the solid particle size in most of the residue solvent system, the cross flow generated by cross flow filtration makes the solid particles difficult to stay and gather on the membrane surface and difficult to block pores, but a small amount of solid particle size in the residue solvent system is close to the membrane pore diameter, and the particles are carried to the membrane surface to block when the solvent penetrates through the membrane due to the action of pressure, so that the filter membrane of the ceramic membrane filter 9 also needs to be cleaned regularly.

In some embodiments, the first filtrate outlet of the dead-end filter is connected with the second inlet of the second flash tower 7 and the filtrate inlet of the ceramic membrane filter 9 through pipelines respectively, the first filtrate outlet of the dead-end filter is connected with the first control valve 11 on the pipeline of the ceramic membrane filter 9, and the second control valve 12 is connected on the pipeline of the first filtrate outlet of the dead-end filter connected with the second flash tower 7;

When the first control valve 11 and the second control valve 12 are communicated, a part of the first filtrate is led into the second flash tower 7, the other part of the first filtrate is led into the ceramic membrane filter 9 for cross-flow filtration to obtain second filtrate and concentrated solution, the second filtrate is led into the first flash tower 8 for flash evaporation to obtain high-grade refined asphalt, and the concentrated solution is led into the second flash tower 7 for flash evaporation after being mixed with the first filtrate, so that the medium-grade refined asphalt is obtained.

When only the second control valve 12 is connected, the first filtrate is led into the second flash tower 7 for flash evaporation, and the medium-grade refined asphalt is obtained.

When only the first control valve 11 is communicated, the first filtrate is led into the ceramic membrane filter 9 for cross-flow filtration to obtain second filtrate and concentrated solution, the second filtrate is led into the first flash tower 8 for flash evaporation to obtain high-grade refined asphalt, and the concentrated solution is led into the second flash tower 7 for flash evaporation to obtain medium-grade refined asphalt.

The ash content of the obtained medium-grade refined asphalt is 0.2-0.6%, and the QI (quinoline insoluble) content is lower than 0.8%. The modified asphalt is mainly used as asphalt binder, raw materials for preparing carbon electrodes, active carbon and the like.

The ash content of the obtained high-grade refined asphalt is lower than 100ppm, and the QI (quinoline insoluble) content is lower than 0.05%. The material is mainly used as raw materials of high-performance asphalt-based carbon fiber, foam carbon, lithium ion battery anode material, needle coke and the like.

It should be noted that the case of communicating only the first control valve 11 is not always used, because the manner of directly introducing the concentrated solution of the ceramic membrane filter 9 into the second flash column 7 to flash out the medium-grade refined asphalt consumes relatively high energy. Thus, when it is desired to produce medium-grade refined asphalt, it is usually performed in such a manner that the first control valve 11 and the second control valve 12 are communicated at the same time.

In some embodiments, the pressure differential between the inlet of the dead-end filter and the first filtrate outlet is greater than 1.5kgf/cm ² Stopping feeding, introducing purge gas into the dead-end filter through the inlet of the dead-end filter, and starting a positive blowing mode, wherein the positive blowing direction is from bottom to top, the auxiliary filtrate is discharged from the first filtrate outlet, and the positive blowing pressure is 3-5kgf/cm ² ；

Wherein if the pressure difference between the inlet of the dead-end filter and the outlet of the first filtrate is less than 1.5kgf/cm ² Stopping the forward blowing, and continuing to introduce the extraction liquid into the dead-end filter;

if the pressure difference between the inlet of the dead-end filter and the outlet of the first filtrate is still greater than 1.5kgf/cm ² Stopping the forward blowing, introducing purge gas into the dead-end filter through the first filtrate outlet, and starting a back blowing mode, wherein the back blowing purge direction is from top to bottom, and the pressure of the back blowing gas is 3-5kgf/cm ² Until the pressure difference between the inlet of the dead-end filter and the outlet of the first filtrate is less than 1.5kgf/cm ² Stopping back blowing, and continuously introducing the extraction liquid into the dead-end filter.

Specifically, the extract separated by centrifuge 3 is continuously pumped into a dead-end filter. When the pressure difference between the inlet of the dead-end filter and the outlet of the first filtrate is greater than 1.5kgf/cm ² Stopping feeding, introducing nitrogen into the dead-end filter through its inlet, and opening positive blowing mode, wherein the nitrogen flow direction is identical to the filtering direction, and the auxiliary filtrate is discharged from the first filtrate outlet, and the positive blowing pressure is 3-5kgf/cm ² After 2-10min of positive blowing, when the pressure difference between the inlet of the dead-end filter and the outlet of the first filtrate is less than 1.5kgf/cm ² When stop N ₂ The extract in centrifuge 3 is again pumped continuously into the dead-end filter by purging. When the pressure difference between the inlet of the dead-end filter and the outlet of the first filtrate is again greater than 1.5kgf/cm ² And stopping feeding and starting the positive blowing mode again. Differential pressure between inlet and outlet of feed-filterGreater than 1.5kgf/cm ² Positive blow-inlet/outlet pressure difference less than 1.5kgf/cm ² -repeating the operation in the fed mode, cyclically. Until the pressure difference between the inlet of the dead-end filter and the outlet of the first filtrate after positive blowing is still more than 1.5kgf/cm ² And stopping the forward blowing mode and entering the reverse blowing mode.

In the back-blowing mode, nitrogen is introduced into the dead-end filter through the first filtrate outlet, the flow direction of the nitrogen is opposite to the filtering direction, the filter cake attached to the surface of the filter element is blown off, the flux of the filtrate is recovered, and the back-blowing gas pressure is 3-5kgf/cm ² Stopping N after back blowing for 2-10min ₂ Back blowing, wherein filter residues on the surface of the filter element are blown to the bottom of the dead-end filter by nitrogen, and the filter element recovers the flux of filtrate. When the pressure difference between the inlet of the dead-end filter and the outlet of the first filtrate is again greater than 1.5kgf/cm ² And stopping feeding, continuously starting a positive blowing mode, and repeating the operation in the positive blowing-reverse blowing-positive blowing mode to circularly perform. The filter residue at the bottom of the filter is discharged periodically.

The inventor realizes that the difficulty of adopting the dead-end filtration technology is that the high-viscosity materials formed by the coal liquefaction residues and the extracting agent are easily adsorbed on the surface of the filter element, the filtration resistance is increased, the filtration and deashing cannot be performed efficiently, only frequent back flushing and cleaning can be performed, the cleaning difficulty is high due to the high-viscosity materials, and the continuous working efficiency is greatly reduced. Therefore, the biggest bottleneck of the dead-end filtration technology for extracting, deashing and refining the coal liquefaction residues is the high viscosity problem of an extraction system. There are two reasons for the high viscosity problem: (1) The temperature, the agent-slag ratio and other technological parameters are unsuitable, and the viscosity of the mixed extraction system of the coking wash oil extractant and the residues is increased under the conditions of lower temperature and lower agent-slag ratio. (2) The extraction effect is poor, the asphalt substances in the residues are not fully extracted and released in the extractant, the viscosity of the asphalt substances is extremely high, the asphalt substances retained in the raffinate phase are extremely easy to form a filtrate barrier layer, and the back-cleaning difficulty is greatly increased.

Therefore, the application adopts the extraction process regulation and control mode suitable for the coal liquefaction residues and the extractant, such as stirring rate, extraction temperature, time, catalyst-to-residue ratio and the like, is beneficial to improving the hot-melting efficiency of the liquefaction residues, reducing the viscosity of an extraction system, improving the separation efficiency of the traditional dead-end filtration, reducing the loss of the extractant, improving the recovery efficiency of the extractant, prolonging the stable operation period of centrifugal separation, common filtration and ceramic membrane filtration, and promoting the improvement of the extraction efficiency and economic performance of the liquefaction residues. And through the mode that positively blowing and blowback combine together, make the pitch class material fully release in the filter residue, reduce the viscosity of filter residue, clear up the filter residue more easily, make filterable process continuous stable.

The refined asphalt is a bright blocky solid at normal temperature, is crisp and easy to grind, adopts the coupling technology of horizontal screw centrifugation-dead end filtration-ceramic membrane filtration, reduces ash content from 16.52 percent of raw materials to less than 100ppm (namely 0.01 percent) of the high-grade refined asphalt, and has a removal rate as high as 99.94 percent; quinoline insoluble substances in the liquefied residue are formed by ash in coal, macromolecular aromatic hydrocarbon formed by pyrolysis and polymerization in the liquefying process and the like, and the coupling technology of horizontal screw centrifugation-dead end filtration-ceramic membrane filtration is adopted, so that the QI is reduced to less than 500ppm (namely 0.05%) of high-grade refined asphalt from 36.5% of raw materials, and the removal rate is as high as 99.86%; the sulfur content of the high-grade refined asphalt is lower than 100ppm; the recovery rate of the heavy extractant can reach 96%, the recovery rate of the light extractant can reach 93%, the yield of refined asphalt can reach 96%, and continuous stable long-period operation can be realized. Nitrogen in the coal liquefaction residues is in the forms of organic pyrrole nitrogen, pyridine nitrogen and the like, hydrogen bonds are formed in the extraction process and are easily extracted, so that the nitrogen content in the refined asphalt is improved, the S element is mainly in an inorganic state and is difficultly dissolved in a solvent from the added catalyst and mineral substances, and most of the S element is removed.

The process has the characteristics of flexibility, variability and suitability for different extraction systems, and different liquefied residue extraction systems (heavy or light extraction systems) adopt process operation modes of preheating and corresponding process parameter modulation. The ultrafiltration operation mode of the ceramic membrane is also changed correspondingly with the change of the physical properties of the feed (the concentration multiple of the concentrated solution, the discharge capacity of the concentrated solution and the feed amount are required to be changed correspondingly). The process technology is suitable for material preparation, is beneficial to long-period stable operation and is beneficial to the improvement of working efficiency.

The application is further illustrated by the following specific examples.

Example 1

A preparation method of refined asphalt comprises the following steps:

s1, adding coking wash oil into a preparation tank 1, starting a circulating pump and a stirring device, and adding powdery coal liquefaction residues when the temperature in the preparation tank 1 is raised to 80 ℃, wherein the mass ratio of the coking wash oil to the coal liquefaction residues is 3:1, introducing nitrogen to regulate the pressure in the tank to be 0.3MPa, continuously heating the oil bath in the preparation tank 1 to 120 ℃, stirring at constant temperature for 30min to obtain slurry, switching the three-way valve to the direction of the metering tank 2, and switching the three-way valve back to a circulating state after the slurry is pumped into the metering tank 2 once.

The property analysis of the coal liquefaction residue is shown in Table 1.

TABLE 1

Project
		Q _net,ar /Kcal/kg	6437
M _t /％	Not detect
		A _d /％	16.52
V _daf /％	40.4
		S _t,d /％	1.96
N _,d /％	0.84
		Quinoline Insolubles (QI)/%	36.5

S2, continuously and stably pumping the slurry into a horizontal decanter centrifuge by a metering tank 2 for solid-liquid separation, wherein the centrifugal temperature is 130 ℃, and an extract is obtained;

s3, introducing the extract into a dead-end filter for filtering, wherein the filtering temperature is 120 ℃, and introducing the obtained first filtrate into a filtrate storage tank 6 for later use;

s4, communicating the first control valve 11 with the second control valve 12, introducing a part of the first filtrate into the second flash tower 7, introducing the other part of the first filtrate into the ceramic membrane filter 9 for cross-flow filtration, wherein the filtration temperature is 120 ℃, obtaining second filtrate and concentrated solution, introducing the second filtrate into the first flash tower 8 for flash evaporation, obtaining high-grade refined asphalt, introducing the concentrated solution into the second flash tower 7 for flash evaporation, and mixing the concentrated solution with the first filtrate, thus obtaining the medium-grade refined asphalt.

The extraction agent is recovered by the dryer 10 and the flash tower, and the recovery rate of the extraction agent is 96%. The yield of refined asphalt was 96.7%, and the switching period of the system filter was more than 40 days. The test of the obtained high-grade refined asphalt shows that: m is M _t ＝0.2，A _d ＝80ppm，V _daf ＝57.65％，S _t,d <0.01，N _,d =1.32%, qi=0.03. The test of the obtained medium-grade refined asphalt shows that: m is M _t ＝0.1，A _d ＝3000ppm，V _daf ＝54.22％，S _t,d ＝0.05，N _,d ＝1.33％，QI＝0.55。

Wherein, extractant recovery rate=extractant recovery amount/extractant usage amount, refined asphalt yield=refined asphalt yield/amount of extractant solubles in coal liquefaction residue, and refined asphalt yield=medium refined asphalt yield+high refined asphalt yield.

Example 2

A preparation method of refined asphalt comprises the following steps:

s1, adding tetrahydrofuran into a preparation tank 1, starting a circulating pump and a stirring device, and adding powdery coal liquefaction residues (the properties are the same as those of the embodiment 1), wherein the mass ratio of the tetrahydrofuran to the coal liquefaction residues is 3:1, introducing nitrogen to regulate the pressure in the tank to 0.3MPa, stirring at normal temperature for 40min to obtain slurry, switching the three-way valve to the direction of the metering tank 2, and switching the three-way valve back to the circulation state after the slurry is pumped into the metering tank 2 once.

S2, continuously and stably pumping the slurry into a horizontal decanter centrifuge by a metering tank 2 for solid-liquid separation to obtain an extract;

s3, introducing the extract into a dead-end filter for filtering to obtain a first filtrate, and introducing the first filtrate into a filtrate storage tank 6 for later use;

s4, communicating the first control valve 11 with the second control valve 12, introducing a part of the first filtrate into the second flash tower 7, introducing the other part of the first filtrate into the ceramic membrane filter 9 for cross-flow filtration to obtain second filtrate and concentrated solution, introducing the second filtrate into the first flash tower 8 for flash evaporation to obtain high-grade refined asphalt, introducing the concentrated solution into the second flash tower 7 for flash evaporation, and mixing the concentrated solution with the first filtrate to obtain the medium-grade refined asphalt.

The extraction agent is recovered by the dryer 10 and the flash tower, and the recovery rate of the extraction agent is 93%. The yield of refined asphalt was 96.5%, and the switching period of the system filter was more than 40 days. The test of the obtained high-grade refined asphalt shows that: m is M _t ＝0.2，A _d ＝70ppm，V _daf ＝58.71％，S _t,d <0.01，N _,d =1.33%, qi=0.04. The test of the obtained medium-grade refined asphalt shows that: m is M _t ＝0.1，A _d ＝3500ppm，V _daf ＝54.03％，S _t,d ＝0.05，N _,d ＝1.32％，QI＝0.58。

Example 3

A preparation method of refined asphalt comprises the following steps:

s1, adding coked wash oil into a preparation tank 1, starting a circulating pump and a stirring device, and adding powdery coal liquefaction residues (the properties are the same as those of the embodiment 1) when the temperature in the preparation tank 1 is raised to 80 ℃, wherein the mass ratio of the coked wash oil to the coal liquefaction residues is 4:1, introducing nitrogen to regulate the pressure in the tank to be 0.3MPa, continuously heating the oil bath in the preparation tank 1 to 120 ℃, stirring at constant temperature for 30min to obtain slurry, switching the three-way valve to the direction of the metering tank 2, and switching the three-way valve back to a circulating state after the slurry is pumped into the metering tank 2 once.

S2, continuously and stably pumping the slurry into a horizontal decanter centrifuge by a metering tank 2 for solid-liquid separation, wherein the centrifugal temperature is 120 ℃, so as to obtain an extract;

S4, communicating the second control valve 12, and introducing the first filtrate into a second flash tower 7 for flash evaporation to obtain the medium-grade refined asphalt.

The extraction agent is recovered by the dryer 10 and the flash tower, and the recovery rate of the extraction agent is 96%. The yield of refined asphalt was 97.3%, and the system filter switching period was greater than 40 days. The test of the obtained medium-grade refined asphalt shows that: m is M _t ＝0.1，A _d ＝2000ppm，V _daf ＝55.18％，S _t,d ＝0.04，N _,d ＝1.3％，QI＝0.5。

Comparative example 1

A preparation method of refined asphalt comprises the following steps:

s1, adding coked wash oil into a preparation tank 1, starting a circulating pump and a stirring device, and adding powdery coal liquefaction residues (the properties are the same as those of the embodiment 1) when the temperature in the preparation tank 1 is raised to 80 ℃, wherein the mass ratio of the coked wash oil to the coal liquefaction residues is 3:1, introducing nitrogen to regulate the pressure in the tank to 0.3MPa, continuously heating the oil bath in the preparation tank 1 to 120 ℃, stirring at normal temperature for 30min to obtain slurry, switching the three-way valve to the direction of the metering tank 2, and switching the three-way valve back to a circulating state after the slurry is pumped into the metering tank 2 once.

S2, continuously and stably pumping the slurry into a dead-end filter by a metering tank 2 for filtering at the temperature of 120 ℃ to obtain a first filtrate, and introducing the first filtrate into a filtrate storage tank 6 for later use;

s3, communicating the first control valve 11 with the second control valve 12, introducing a part of the first filtrate into the second flash tower 7, introducing the other part of the first filtrate into the ceramic membrane filter 9 for cross-flow filtration, wherein the filtration temperature is 120 ℃, obtaining second filtrate and concentrated solution, introducing the second filtrate into the first flash tower 8 for flash evaporation, obtaining high-grade refined asphalt, introducing the concentrated solution into the second flash tower 7 for flash evaporation, and mixing the concentrated solution with the first filtrate, thus obtaining the medium-grade refined asphalt.

The extraction agent is recovered by the dryer 10 and the flash tower, and the recovery rate of the extraction agent is 95%. The yield of refined asphalt was 96% and the system filter switching period was 15 days. The test of the obtained high-grade refined asphalt shows that: m is M _t ＝0.2，A _d ＝90ppm，V _daf ＝57.85％，S _t,d <0.01，N _,d =1.32%, qi=0.04. The test of the obtained medium-grade refined asphalt shows that: m is M _t ＝0.3，A _d ＝2500ppm，V _daf ＝54.73％，S _t,d ＝0.04，N _,d ＝1.31％，QI＝0.52。

Comparative example 2

A preparation method of refined asphalt comprises the following steps:

and S3, introducing the extract into a ceramic membrane filter 9 for cross-flow filtration to obtain second filtrate and concentrated solution, introducing the second filtrate into a first flash evaporation tower 8 for flash evaporation to obtain high-grade refined asphalt, and introducing the concentrated solution into a second flash evaporation tower 7 for flash evaporation to obtain medium-grade refined asphalt.

The dryer 10 and the flash tower recover and extract the extractantThe recovery rate of the agent was 93.5%. The yield of refined asphalt was 96.5%, and the system filter switching period was 5 days. The test of the obtained high-grade refined asphalt shows that: m is M _t ＝0.3，A _d ＝95ppm，V _daf ＝57.25％，S _t,d <0.01，N _,d =1.35%, qi=0.04. The test of the obtained medium-grade refined asphalt shows that: m is M _t ＝0.1，A _d ＝3500ppm，V _daf ＝54.03％，S _t,d ＝0.05，N _,d ＝1.32％，QI＝0.58。

Comparative example 3

A preparation method of refined asphalt comprises the following steps:

s1, adding coked wash oil into a preparation tank 1, starting a circulating pump and a stirring device, and adding powdery coal liquefaction residues (the properties are the same as those of the embodiment 1), wherein the mass ratio of the coked wash oil to the coal liquefaction residues is 6:1, introducing nitrogen to regulate the pressure in the tank to 0.3MPa, stirring at normal temperature for 30min to obtain slurry, switching the three-way valve to the direction of the metering tank 2, and switching the three-way valve back to the circulation state after the slurry is pumped into the metering tank 2 once.

S2, continuously and stably pumping the slurry into cyclone separation equipment by a metering tank 2 to perform solid-liquid separation to obtain an extract;

The extraction agent is recovered by the dryer 10 and the flash tower, and the recovery rate of the extraction agent is 94.5%. The yield of refined asphalt was 84% and the switching period of the system filter was 7 days. The test of the obtained high-grade refined asphalt shows that: m is M _t ＝0.3，A _d ＝73ppm，V _daf ＝58.49％，S _t,d <0.01，N _,d =1.3%, qi=0.03. The test of the obtained medium-grade refined asphalt shows that: m is M _t ＝0.1，A _d ＝2100ppm，V _daf ＝54.93％，S _t,d ＝0.03，N _,d ＝1.34％，QI＝0.51。

Comparative example 4

A preparation method of refined asphalt comprises the following steps:

s1, adding a mixture of coking wash oil and 10% NMP into a preparation tank 1, starting a circulating pump and a stirring device, and adding powdery coal liquefaction residues when the temperature in the preparation tank 1 is raised to 80 ℃ (the properties are the same as those of the example 1), wherein the mass ratio of the coking wash oil to the coal liquefaction residues is 1:1, introducing nitrogen to regulate the pressure in the tank to 0.3MPa, stirring at normal temperature for 40min to obtain slurry, switching the three-way valve to the direction of the metering tank 2, and switching the three-way valve back to the circulation state after the slurry is pumped into the metering tank 2 once.

and S3, introducing the extract into a dead-end filter for filtering, wherein the filtering temperature is 120 ℃, and obtaining a first filtrate for flash evaporation to obtain the medium-grade refined asphalt.

The extraction agent is recovered by the dryer 10 and the flash tower, and the recovery rate of the extraction agent is 96%. The yield of refined asphalt was 87% and the switching period of the system filter was 36 days. The test of the obtained medium-grade refined asphalt shows that: m is M _t ＝0.4，A _d ＝5000ppm，V _daf ＝53.13％，S _t,d ＝0.09，N _,d ＝1.35％，QI＝0.78。

The test results of the examples and comparative examples are detailed in Table 2.

TABLE 2

Analysis of results:

the test results of examples 1-3 are all satisfactory.

Comparative example 1 is different from example 1 in that comparative example 1 does not employ a decanter centrifuge for solid-liquid separation, resulting in shortening the switching cycle of the dead-end filter to 15 days. The reason is that the horizontal screw centrifugal process is not carried out, so that more ash particles enter the dead-end filter, the dead-end filter needs to be cleaned frequently, and then the dead-end filter needs to be switched frequently, so that the switching period of the filter is shortened, and the continuous operation time of the whole system is influenced.

Comparative example 2 differs from example 2 in that comparative example 2 lacks a dead-end filtration step, resulting in a shortened switching period of ceramic membrane filter 9 to 5 days. The reason is that the dead-end filtering process is not performed, so that more ash particles enter the ceramic membrane filter 9, frequent cleaning of the ceramic membrane filter 9 is required, frequent switching of the ceramic membrane filter 9 is required, the switching period of the filter is shortened, and the continuous operation time of the whole system is influenced. And the filtration accuracy of the ceramic membrane filter 9 is higher than that of the dead-end filter, the early dead-end filtration is lacked, so that more ash enters the ceramic membrane filter 9, and the cleaning frequency of the ceramic membrane filter 9 is greatly increased than that of the dead-end filter, so that the switching period of the ceramic membrane filter 9 is shorter than that of the dead-end filter of comparative example 1.

Comparative example 3 compared with example 1, comparative example 3 was not heated during dissolution, solid-liquid separation, and filtration, and the catalyst to slag ratio exceeded the maximum range 5:1, the solid-liquid separation adopts a cyclone separation mode, so that the yield of the final refined asphalt is reduced to 84 percent, and the switching period is reduced to 7 days. Since the coked wash oil is a heavy extractant, if it is not heated during dissolution, solid-liquid separation, and filtration, the solubility of the extractant by the effective substances (heavy oil and asphaltene) in the coal liquefaction residue decreases, resulting in a decrease in the yield of the final refined asphalt. And excessive extractant can cause the entrainment of the effective substances (heavy oil, asphaltenes) in the coal liquefaction residue to the raffinate discharge during the cyclone separation process. The solid-liquid separation effect of the cyclone separation mode is good without the horizontal screw centrifugation effect, ash particles can enter the subsequent filter, the dead-end filter and the ceramic membrane filter 9 need to be cleaned frequently, and then the dead-end filter and the ceramic membrane filter 9 need to be switched frequently, so that the switching period of the filter is shortened, and the continuous operation time of the whole system is influenced.

Comparative example 4 compared to example 3, the slag ratio in comparative example 4 was 1:1 and no ceramic membrane filtration was used, resulting in a reduction in the yield of refined asphalt of 87%, a switching cycle of 36 days and an increase in sulfur content to 0.09%. This is due to the slag ratio of 1:1, below the minimum range 2 of the present application: 1, the effective substances (heavy oil and asphaltene) in the coal liquefaction residues are not completely extracted, so that the yield of the final refined asphalt is reduced, the viscosity of the system is increased, ash is not easy to separate out during centrifugation, more ash enters a dead-end filter, and compared with the embodiment 3, the dead-end filter needs to be frequently switched, the switching period of the filter is shortened, and the continuous operation time of the whole system is influenced. But the effect is less than in comparative examples 1-3. And as the ceramic membrane filtration process is not adopted, more ash particles remain in the final product refined asphalt, and sulfur element is a component part of ash, so that the sulfur content is increased.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present invention.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.

In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

In the present invention, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

The terms "some embodiments," "some specific embodiments," and the like, herein refer to a particular feature, structure, material, or characteristic described in connection with the embodiment being included in at least one embodiment of the invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in any one or more embodiments. Furthermore, the various embodiments described in this specification, as well as the features of the various embodiments, can be combined and combined by one skilled in the art without contradiction.

While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.

Claims

1. A system for producing refined asphalt, comprising:

the preparation tank is used for adding an extractant and coal liquefaction residues, mixing and pulping;

the centrifugal machine is provided with a feed inlet, an extract liquid discharge port and a raffinate discharge port, and the feed inlet is connected with the preparation tank;

The dead-end filter is connected with the extract discharge port of the centrifugal machine so as to introduce extract into the dead-end filter for filtering, and a first filtrate is obtained;

the ceramic membrane filter is provided with a filtrate inlet, a second filtrate outlet and a concentrated solution outlet, the filtrate inlet is connected with the dead-end filter, so that the first filtrate is led into the ceramic membrane filter for cross-flow filtration to obtain second filtrate and concentrated solution, the second filtrate is discharged from the second filtrate outlet, and the concentrated solution is discharged from the concentrated solution outlet;

the first flash tower is connected with the second filtrate outlet of the ceramic membrane filter so as to flash the second filtrate to obtain high-grade refined asphalt;

and the second flash tower is connected with the concentrated solution outlet of the ceramic membrane filter so as to flash the concentrated solution to obtain the medium-grade refined asphalt.

2. The refined asphalt production system of claim 1, wherein the first flash column has a first inlet, a first outlet, and a second outlet, the first inlet being connected to the second filtrate outlet of the ceramic membrane filter, the first outlet being for discharging the flash separated extractant, the second outlet being for discharging the separated higher refined asphalt;

3. The refined asphalt production system according to claim 1, wherein the dead-end filter includes a first dead-end filter and a second dead-end filter, the extract discharge port of the centrifuge is connected to the first dead-end filter and the second dead-end filter through pipes, respectively, and control valves are connected to the pipes connecting the first dead-end filter and the second dead-end filter, respectively, so that at any point of time, either one of the first dead-end filter and the second dead-end filter is in operation.

4. The refined asphalt production system according to claim 1, wherein the dead-end filter is connected with a forward blowing pipe and a reverse blowing pipe, the dead-end filter has an inlet, the first filtrate outlet and a cake outlet, the inlet of the dead-end filter is located at a lower portion of the dead-end filter, the first filtrate outlet is located at an upper portion of the dead-end filter, the cake outlet is located at a bottom portion of the dead-end filter, the forward blowing pipe is connected to the inlet of the dead-end filter, and the reverse blowing pipe is connected to the first filtrate outlet of the dead-end filter.

5. The refined asphalt production system of claim 1, further comprising a dryer having a first filter cake inlet, a second filter cake inlet, a dry filter cake outlet, and an extractant outlet, the first filter cake inlet connected to the raffinate outlet of the centrifuge, the second filter cake inlet connected to the filter cake outlet of the dead-end filter.

6. The refined asphalt production system of claim 1, wherein heating devices are provided in the preparation tank, the centrifuge, the dead-end filter, and the ceramic membrane filter.

7. The system for producing refined asphalt according to claim 1, wherein the centrifuge is a decanter centrifuge, the separation line speed is 80-160m/s, and the separation temperature is normal temperature to 150 ℃.

8. A process for producing a refined asphalt, characterized by using the production system according to any one of claims 1 to 7, comprising the steps of:

9. The method for producing refined asphalt according to claim 8, wherein the first filtrate outlet of the dead-end filter is connected to the second inlet of the second flash column and the filtrate inlet of the ceramic membrane filter through pipes, respectively, the first filtrate outlet of the dead-end filter is connected to a first control valve on a pipe of the ceramic membrane filter, and the first filtrate outlet of the dead-end filter is connected to a second control valve on a pipe of the second flash column;

10. The method for producing a purified asphalt according to claim 8, wherein when the pressure difference between the inlet of the dead-end filter and the outlet of the first filtrate is greater than 1.5kgf/cm ² Stopping feeding, introducing purge gas into the dead-end filter through the inlet of the dead-end filter, and starting a positive blowing mode to assist filtrate to be discharged from the first filtrate outlet, wherein the positive blowing pressure is 3-5kgf/cm ² ；

Wherein,if the pressure difference between the inlet of the dead-end filter and the first filtrate outlet is less than 1.5kgf/cm ² Stopping the forward blowing, and continuing to introduce the extraction liquid into the dead-end filter;