Coal-to-liquids production system

Abstract

The utility model relates to the technical field of coal oil, disclose a kind of preparation system of coal oil, for solving the problem that vacuum tower bottom oil high temperature, high viscosity, high solid content is difficult to purify. The system is by adding solvent, after being fully mixed by dilution mixer again, reduce tower bottom oil viscosity and dissolve part asphaltene etc., using the high-precision filter with metal sintering membrane filter element is carried out precision filtration, and equipped with backwash system and slag receiving tank realize continuous slagging and slag collection, can effectively remove solid impurities, obtain clean oil product, mainly used in the purification treatment of vacuum tower bottom oil in coal direct liquefaction process, provide high-end raw material for downstream.

Description

Technical Field

[0001] This utility model relates to the field of coal-to-oil technology. More specifically, this utility model relates to a coal-to-oil preparation system. Background Technology

[0002] Coal direct liquefaction (CDL) technology can convert coal resources into liquid fuels, improving energy self-sufficiency from an energy security perspective. From an environmental protection and emission reduction perspective, CDL can reduce pollutant emissions from direct coal combustion, thus lowering environmental pollution. From an economic development perspective, CDL can promote the deep processing and conversion of coal resources, driving the development of related industrial chains. However, after the reaction in the reactor, the oil in CDL contains a large number of solid particles. During downstream transportation, solid sedimentation leads to problems such as pipe blockage, valve wear, and instrument clogging. Currently, CDL desolvation technologies mainly use centrifugation, sedimentation, or the addition of chemicals. However, these methods are largely ineffective against particles smaller than 5 micrometers, resulting in complete blockage after three months of operation, rendering the solid-containing oil only suitable for low-end processing. Therefore, removing solids from the oil to improve the overall product value of the entire chain is crucial, and the heavy components can be used as strategic materials for national development. Utility Model Content

[0003] One object of this invention is to solve at least the problems described above and to provide at least the advantages that will be explained later.

[0004] In order to achieve these objectives and other advantages according to the present invention, a coal-to-oil preparation system is provided, wherein the preparation system is provided with a vacuum tower bottom oil purification device, the vacuum tower bottom oil purification device being located at the bottom outlet of the vacuum tower in the preparation system.

[0005] Preferably, the vacuum tower bottom oil purification device includes: The dilution mixer has its inlet pipes connected to the bottom outlet pipe of the vacuum distillation tower and a light component solvent delivery pipe, respectively, for mixing and diluting the bottom oil with the light component solvent; The high-precision filter has its inlet connected to the outlet of the dilution mixer via a feed pipe. The high-precision filter has multiple metal sintered membrane filter elements inside. The metal sintered membrane filter elements adopt an outside-to-in filter flow channel. The backflush air inlet of the high-precision filter is connected to a high-pressure air source via a backflush pipe. A first electric valve is installed on the backflush pipe. The slag receiving tank has its inlet connected to the bottom slag discharge port of the high-precision filter via a slag discharge pipeline. It is used to receive the solid slag-containing liquid that is filtered, intercepted, and discharged during backwashing.

[0006] Preferably, it also includes: The slag-liquid treatment unit has its inlet connected to the outlet of the slag receiving tank via a slag-liquid conveying pump; the slag-liquid treatment unit is provided with at least two discharge pipelines: the first discharge pipeline is connected to the upstream coal slurry preparation system, and the second discharge pipeline is connected to a solvent recovery and spray drying device.

[0007] Preferably, the filtration accuracy of the metal sintered membrane filter element is 0.05~0.5 micrometers.

[0008] Preferably, the clear liquid outlet of the high-precision filter is connected to a purified oil output pipeline for transporting the clean vacuum tower bottom oil after solid removal to the downstream as a high-end raw material, and a second electric valve is provided on the purified oil output pipeline.

[0009] Preferably, the high-precision filter has probes for differential pressure detection devices located below and below the tube sheet, which are used to automatically trigger the backwashing program when the differential pressure inside and outside the filter element of the high-precision filter reaches a set value.

[0010] Preferably, the high-precision filter housing is made of a high-temperature and high-pressure resistant alloy material, with a design operating temperature of 260°C to 280°C and a design operating pressure of 1.0 MPa to 1.2 MPa.

[0011] Preferably, multiple high-precision filters are provided, and the multiple high-precision filters are connected in parallel: Each high-precision filter is equipped with a third electric valve on its backflush line. The backflush lines of multiple high-precision filters are connected to a main backflush line. The first electric valve is located on the main backflush line. Each high-precision filter is equipped with a fourth electric valve on its feed pipe. The feed pipes of multiple high-precision filters are connected to a main feed pipe, which is connected to the outlet of the dilution mixer. Each high-precision filter is equipped with a fifth valve on its slag discharge pipeline. The slag discharge pipelines of multiple high-precision filters are connected to a main slag discharge pipeline, which is connected to the slag receiving tank.

[0012] This invention has at least the following beneficial effects: It can efficiently remove solid impurities from the bottom oil of a vacuum distillation tower, obtaining clean, high-value-added oil; by combining dilution mixing with high-precision filtration, it effectively solves the problem of difficult filtration of bottom oil with high viscosity and high solid content; the backwashing system and parallel filtration design enable uninterrupted continuous operation with a high degree of automation; the entire device is resistant to high temperature and high pressure, operates safely and stably, and is easy to integrate into existing processes, significantly improving resource utilization and economic benefits.

[0013] Other advantages, objectives and features of this invention will be partly apparent from the following description, and partly understood by those skilled in the art through study and practice of this invention. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the pipeline connection of the coal-to-oil preparation system described in this utility model; Figure 2 This is a schematic diagram of the pipeline connection when the vacuum tower bottom oil purification device of this utility model contains multiple high-precision filters. Detailed Implementation

[0015] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0016] It should be noted that in the description of this utility model, the terms "horizontal", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0017] like Figure 1 As shown, this utility model provides a coal-to-oil preparation system, wherein the preparation system is equipped with a vacuum tower bottom oil purification device, which is located at the bottom outlet of the vacuum tower in the preparation system.

[0018] Specifically, the preparation system includes a preheater, a reactor, a high-temperature separator, a low-temperature separator, a first atmospheric pressure tower, a vacuum tower, a vacuum tower bottom oil purification device, and a second atmospheric pressure tower connected in sequence.

[0019] This coal-to-oil production system comprises a series of connected devices arranged in a sequential process. The materials (coal slurry, hydrogen, and catalyst) first enter a preheater to be heated to the required reaction temperature, and then enter the reactor for core reactions such as hydrogenation and liquefaction. The reaction products then flow through a high-temperature separator and a low-temperature separator for preliminary gas-liquid separation. The separated liquid oil enters the first atmospheric distillation column, where light fractions are separated. The remaining heavy components enter a vacuum distillation column, where various fractions are further separated under negative pressure. The final residue is the high-viscosity, high-solids-content vacuum distillation column bottom oil. This poorly treated bottom oil is not directly discharged as residue or subjected to simple treatment; instead, it is immediately introduced into a vacuum distillation column bottom oil purification unit directly connected to it. After efficient purification by this unit, the clean oil, free of solid impurities, is then sent to the second atmospheric distillation column for final rectification separation, yielding various qualified products.

[0020] The vacuum distillation tower bottom oil purification unit is integrated into this specific location, and its operation is seamlessly coupled with the entire system. For example, the hot oil discharged from the bottom of the vacuum distillation tower can be directly introduced into the dilution mixer of the purification unit, while the clean oil produced by the purification unit is sent as high-quality feed to the second atmospheric distillation tower, and the recovered light component solvents can also be recycled. This integration completely changes the traditional way of handling difficult materials such as vacuum distillation tower bottom oil.

[0021] This system-level integration brings profound technical and economic benefits. Its most direct effect is a significant improvement in the product yield and quality of the entire preparation system. Through deep purification, the previously unusable or even harmful vacuum distillation column bottom oil is transformed into a high-value, clean feedstock, which can then be effectively separated into useful products in the second atmospheric distillation column, reducing waste emissions and improving resource utilization. Secondly, it fundamentally protects the downstream second atmospheric distillation column and its reboiler, heat exchanger, and other equipment, preventing coking, wear, and blockage caused by solid particles, significantly extending the service life and maintenance cycle of key equipment, and ensuring the safe, stable, long-term, full-capacity, and high-quality operation of the entire system. Ultimately, this design makes the entire coal-to-oil preparation process more complete, efficient, and modern, creating significant economic benefits by improving the quality of the final product and reducing operating and maintenance costs, thus enhancing the overall competitiveness of the process technology.

[0022] Furthermore, the vacuum tower bottom oil purification device includes: The dilution mixer has its inlet pipes connected to the bottom outlet pipe of the vacuum distillation tower and a light component solvent delivery pipe, respectively, for mixing and diluting the bottom oil with the light component solvent; The high-precision filter has its inlet connected to the outlet of the dilution mixer via a feed pipe. The high-precision filter has multiple metal sintered membrane filter elements inside. The metal sintered membrane filter elements adopt an outside-to-in filter flow channel. The backflush air inlet of the high-precision filter is connected to a high-pressure air source via a backflush pipe. A first electric valve is installed on the backflush pipe. The slag receiving tank has its inlet connected to the bottom slag discharge port of the high-precision filter via a slag discharge pipeline. It is used to receive the solid slag-containing liquid that is filtered, intercepted, and discharged during backwashing.

[0023] The above technical solution constructs a highly efficient, continuous filtration system that can be integrated into existing processes through the combination and connection of a series of specific devices. Its workflow begins at the bottom outlet of the vacuum distillation tower, where the high-solids, high-viscosity concentrated coal-to-oil output is first introduced into a dedicated dilution mixer. In this device, the bottom oil is thoroughly mixed and diluted in a specific ratio with solvent supplied by the light component solvent delivery pipeline (typically derived from the light oil fraction from the side stream of the atmospheric distillation tower in the same direct coal liquefaction process). This step is crucial, as it significantly reduces the viscosity of the feed oil, improves its fluidity, and creates the necessary conditions for subsequent high-precision filtration. Simultaneously, the solvent's dissolving effect on large molecules such as asphaltenes helps prevent clogging by colloidal substances during the filtration process.

[0024] The diluted and viscosity-reduced bottom oil mixture is then fed into the feed inlet of a high-precision filter via a feed line. The core component of this filter is a series of sintered metal-coated filter elements installed inside. These elements employ an outside-to-inside filtration channel design, forcing the bottom oil to flow from the outside of the filter element to the inner central tube. Solid particles in the mixture are precisely intercepted and retained on the outer surface of the filter element, gradually forming a filter cake; while the clean liquid passing through the filter element (i.e., the clean vacuum distillation column bottom oil with solids removed) flows out from the clean liquid outlet at the top of the filter and can be transported downstream via a purified oil output line as a high-quality raw material for the production of advanced carbon materials.

[0025] As filtration continues, solid particles accumulate on the outer surface of the filter element, causing the pressure difference between the filter inlet and outlet to gradually increase. When the pressure difference reaches a preset critical value, the backwashing system is triggered or manually activated. This system consists of a high-pressure air source (nitrogen can be used), a first electric valve, etc. Under pressure, the gas flows through the backwash line connected to the filter, pressurizing the space above the filter tube sheet. This pressure effectively peels off and flushes away the solid filter cake adhering to the outer surface of the filter element. The high-concentration solid-laden liquid flushed down is discharged through the slag discharge port at the bottom of the filter.

[0026] The solid-laden liquid discharged from the bottom discharge port of the high-precision filter is collected in a dedicated slag receiving tank via a slag discharge pipeline. This tank serves as a buffer and temporary storage container, receiving the mixture rich in solid particles from normal slag discharge during filtration interception and from backwashing operations. Thus, the purification unit completes its core purification task for the vacuum tower bottom oil: effectively removing solids and recovering clean oil, while collecting the generated waste residue for subsequent processing.

[0027] In summary, this device, through a continuous process of "dilution-high-precision filtration-automatic backwashing-sludge collection," successfully solves the technical challenge of efficiently purifying the bottom oil of vacuum distillation towers with high temperature, high viscosity, and high solids content. This not only ensures the stable operation of downstream equipment but also significantly enhances the value of the final product and the economic efficiency of the entire process.

[0028] Furthermore, the vacuum tower bottom oil purification device also includes: The slag-liquid treatment unit has its inlet connected to the outlet of the slag receiving tank via a slag-liquid conveying pump; the slag-liquid treatment unit is provided with at least two discharge pipelines: the first discharge pipeline is connected to the upstream coal slurry preparation system, and the second discharge pipeline is connected to a solvent recovery and spray drying device.

[0029] The above technical solution includes a specific configuration of the slag-liquid treatment unit, its connection method, and the downstream discharge path. The inlet of this slag-liquid treatment unit is connected to the outlet of the slag receiving tank via a slag-liquid transfer pump, ensuring that the solid-containing slag-liquid can be stably transported into the treatment unit. This unit has at least two discharge pipelines, each pointing in a different direction for subsequent processing. The first discharge pipeline connects to the upstream coal slurry preparation system, allowing some reusable slag-liquid to be directly returned to the slurry preparation process, participating in the reaction again as part of the raw materials, thereby achieving material recycling and resource utilization. The second discharge pipeline is connected to a solvent recovery and spray drying device for further processing of slag-liquid that is unsuitable for direct reuse or has a high solids content. Component separation and waste reduction are achieved through solvent recovery and solid drying.

[0030] In actual operation, the solid-containing slag liquid collected from the slag receiving tank is steadily pumped into the slag liquid treatment unit by the slag liquid transfer pump. The output path can be flexibly selected through valve control based on its solid content, component characteristics, and process requirements. For example, when the solid particles in the slag liquid are small, the solvent content is high, and it has good compatibility with coal slurry, it can be sent back to the coal slurry preparation system through the first pipeline, reducing both the consumption of fresh solvent and the discharge of solid waste. Conversely, if the slag liquid contains a large amount of large solid particles or harmful components that are difficult to reuse directly, it is led to the second pipeline into the solvent recovery and spray drying unit. In this unit, the usable solvent components are first recovered through heating or flash evaporation, and the remaining solid residue is spray-dried into powder for easy transportation or further disposal.

[0031] This configuration significantly expands the functional scope and applicability of the entire purification unit, strengthening the material circulation within the process system, improving resource utilization, and providing a suitable and economical outlet for filter residues of different properties. Thus, while ensuring the stable operation of the main process, it enhances the environmental friendliness and economy of the entire coal-to-oil system.

[0032] Furthermore, the filtration accuracy of the metal sintered membrane filter element is 0.05~0.5 micrometers.

[0033] Specifically, the filtration accuracy of the metal sintered membrane filter element can be set to 0.1 micrometers.

[0034] The aforementioned technical solution specifies that the filtration precision of the metal sintered membrane filter element is 0.05~0.5 micrometers, preferably 0.1 micrometers. This extremely high filtration precision means that the filter element can effectively intercept and remove most solid particles larger than this precision in the oil, including fine catalyst powder, coke particles, inorganic minerals, and other impurities, thereby achieving deep purification.

[0035] During operation, the bottom oil from the vacuum tower, after viscosity reduction treatment by the dilution mixer, is pumped into high-precision filters and flows through these filter elements. Driven by pressure, the bottom oil strictly follows a path from the outside to the inside of the filter element. Because the sintered metal substrate of the filter element is coated with a precise porous membrane layer, its pore structure ensures that only molecules and liquids smaller than this precision can pass through, while all solid particles larger than this precision are trapped on the outer surface of the filter element. For example, in direct coal liquefaction, after the reactor reaction, the oil contains a large number of solid particles. During downstream transport, solid sedimentation leads to problems such as pipe blockage, valve wear, and instrument clogging. Currently, coal-to-oil desolidification technologies mainly use methods such as centrifugation, sedimentation, or the addition of chemicals. However, particles smaller than 5 micrometers are generally impossible to remove using these methods. This filtration precision precisely addresses this problem, ensuring extremely high cleanliness of the purified oil.

[0036] The adoption of this high-precision filtration has yielded significant technical benefits. Its most direct effect is the production of highly pure purified oil products. These clean oils can serve as premium raw materials for the production of high-end carbon materials, specialty fuels, or fine chemicals, greatly enhancing the added value and market competitiveness of the products. Simultaneously, deep filtration significantly reduces the risk of scaling, wear, and clogging in downstream processing equipment (such as heat exchangers, catalyst beds, and high-pressure pumps) caused by solid particles, extending equipment lifespan and reducing unplanned downtime and maintenance costs. Furthermore, high-precision filtration creates stable feeding conditions for subsequent finer separation or catalytic processing units, ensuring the long-term, stable, and efficient operation of the entire production process.

[0037] Furthermore, the high-precision filter's clear liquid outlet is connected to a purified oil output pipeline, which is used to transport the clean vacuum tower bottom oil after solid removal to the downstream as a high-end raw material. A second electric valve is installed on the purified oil output pipeline.

[0038] The aforementioned technical solution specifically involves the output and control method of the clean product produced by the high-precision filter. The solution specifies that a dedicated purified oil output pipeline is connected to the clear liquid outlet at the top of the high-precision filter. The core function of this pipeline is to stably transport the clean, vacuum tower bottom oil, after the solid impurities have been deeply removed by the filter element, to the downstream process.

[0039] During operation, after the bottom oil passes through a high-precision filter for solid-liquid separation, the resulting clean liquid collects at the top of the filter and exits through the clean liquid outlet. At this point, the purified oil output pipeline takes on the task of transporting qualified products. To achieve precise automatic control of this critical pipeline, the design specifically specifies the installation of a second electric valve. This valve, as a key control element, directly determines whether the purified oil can flow downstream. For example, during the filter's normal filtration cycle, the second electric valve is open, allowing a continuous output of pure oil; however, when the system requires backwashing or a downstream equipment malfunctions, the control system can immediately issue a command to close the valve, thereby quickly cutting off the flow and effectively preventing the mixing of unqualified materials or the impact of system pressure fluctuations on product quality.

[0040] This setup brings several significant technical benefits. First, it ensures that only purified oil meeting quality requirements is sent to subsequent processes, serving as a high-quality raw material for producing high-end carbon materials or specialty oils, thus guaranteeing the purity and value of the final product. Second, the introduction of the second electric valve greatly enhances the automation and reliability of the entire purification unit, achieving precise output control and system safety interlocks, reducing the risk of human intervention and operational errors. Finally, this configuration allows the main filtration process and regeneration operations such as backwashing to be performed more flexibly and independently, and the switching and isolation between parallel filters are smoother, thereby ensuring the continuity and stability of the entire production process and improving the overall economic efficiency of the unit.

[0041] Furthermore, the high-precision filter is equipped with probes for differential pressure detection devices below and below the tube sheet, which are used to automatically trigger the backwashing program when the differential pressure inside and outside the filter element of the high-precision filter reaches a set value.

[0042] In the above technical solution, the high-precision filter has probes for differential pressure detection devices located below and below the tube sheet. These differential pressure detection devices can be selected from differential pressure transmitters (range 0-0.6MPa) to monitor the pressure difference inside and outside the filter element in real time. The differential pressure detection device and control system continuously or periodically collect the pressure difference between the inlet and outlet of the high-precision filter. This pressure difference directly reflects the thickness of the filter cake on the filter element surface and its degree of clogging.

[0043] During actual filter operation, as solid particles accumulate on the outer surface of the sintered metal membrane filter element, the flow channel gradually narrows, increasing fluid resistance. This leads to a rise in filter inlet pressure and a relative decrease in outlet pressure, causing the pressure difference between the two to continuously increase. The differential pressure detection device transmits this pressure difference signal to the control system in real time. The control system has a preset key trigger value, typically determined experimentally and by calculation based on the filter element's maximum dirt-holding capacity and the system's allowable pressure drop; for example, it might be set to 0.35 MPa. When the real-time monitored pressure difference reaches or exceeds this set value, the control system automatically determines that the filter needs cleaning and regeneration, and then triggers the backwashing procedure.

[0044] The control system automatically issues a series of logically rigorous commands. Typically, it first closes the inlet and outlet valves on the main pipeline of the filter to isolate it from the production sequence. Then, it sequentially opens the first electric valve on the backflush pipeline, injecting high-pressure gas to pressurize the space above the tube sheet. The entire process requires no manual judgment or intervention, achieving complete automation.

[0045] This automated differential pressure control backwashing mechanism brings significant technical advantages and effects. It fundamentally avoids two drawbacks of manual timed backwashing: first, the waste of resources and frequent start-ups and shutdowns caused by premature backwashing before the filter elements are fully utilized; second, the risk of a sharp drop in filtration efficiency, abnormally high energy consumption, or even filter element damage due to severely clogged filter elements not being flushed in time. By performing precise backwashing at the most appropriate time, the filtration capacity of the filter element is maximized, ensuring stable purified oil production while significantly saving backwashing media consumption. Ultimately, this design ensures that the entire purification unit can operate automatically and continuously under optimal conditions for a long period, stably and efficiently, greatly improving the system's intelligence level and economic benefits.

[0046] Furthermore, the high-precision filter housing is made of a high-temperature and high-pressure resistant alloy material, with a design operating temperature of 260°C to 280°C and a design operating pressure of 1.0MPa to 1.2MPa. For example, Q345R or Luoyang molybdenum steel can be selected.

[0047] In the above technical solution, this design specification ensures the mechanical integrity and long-term operational reliability of the filter, enabling it to adapt to the harsh operating conditions of the bottom oil in the upstream vacuum distillation tower.

[0048] In the actual operation of direct coal liquefaction processes, the bottom oil output from the vacuum distillation tower is maintained at a high temperature to prevent heavy components such as asphaltene from solidifying or viscous from increasing sharply due to cooling during transport. Simultaneously, the subsequent high-precision filtration process also needs to be carried out under a certain system pressure. This is to overcome the flow resistance of the filter element and maintain the necessary filtration driving force, and also to keep the light solvent components in the bottom oil in a liquid state to prevent vaporization. For example, if the operating pressure is too low, the solvent may vaporize at high temperatures, forming an airlock inside the filter element, severely disrupting the filtration process and causing the unit to malfunction. Therefore, the filter housing is designed to operate safely under extreme conditions of 1.2 MPa and 280°C, providing sufficient safety margin to cope with various fluctuating operating conditions.

[0049] This specialized design for high-temperature and high-pressure conditions brings multiple significant technical benefits. The primary benefit is ensuring seamless integration and condition matching between the core filtration unit and the entire coal-to-oil process, avoiding the enormous energy losses and process complexity caused by drastic cooling and depressurization of materials before filtration due to temperature and pressure incompatibility. Secondly, the robust alloy shell can withstand repeated pressure fluctuations and thermal stress changes during filtration and backwashing cycles, greatly extending the equipment's service life and reducing unplanned shutdowns due to equipment failure. Finally, this reliable design is the fundamental prerequisite for ensuring the safe, stable, and long-term continuous operation of the entire purification unit and subsequent processes, playing a decisive role in improving the economic efficiency and operational stability of the entire production unit.

[0050] Furthermore, such as Figure 2 As shown, multiple high-precision filters are installed, and these high-precision filters are connected in parallel: Each high-precision filter is equipped with a third electric valve on its backflush line. The backflush lines of multiple high-precision filters are connected to a main backflush line. The first electric valve is located on the main backflush line. Each high-precision filter is equipped with a fourth electric valve on its feed pipe. The feed pipes of multiple high-precision filters are connected to a main feed pipe, which is connected to the outlet of the dilution mixer. Each high-precision filter is equipped with a fifth valve on its slag discharge pipeline. The slag discharge pipelines of multiple high-precision filters are connected to a main slag discharge pipeline, which is connected to the slag receiving tank.

[0051] The aforementioned technical solution proposes an implementation scheme using multiple high-precision filters operating in parallel. This scheme aims to solve the technical bottleneck of interrupting filtration operations during backwashing of a single filter, thus causing discontinuity in the entire plant's production. Its core lies in organically combining multiple high-precision filters into a single unit through a carefully designed parallel piping and valve system, enabling flexible switching of operating states between the individual filters.

[0052] In terms of specific configuration, each high-precision filter connected in parallel is equipped with an independent valve group to achieve isolation and control of its inlet and outlet materials. Each filter's backflush line is equipped with a third electric valve, and all these independent branches are then connected to a main backflush line. The aforementioned first electric valve is installed on this main line, responsible for controlling the fluid source of the entire backflush system. On the feed side, each filter's feed line is equipped with a fourth electric valve, and the feed branches of multiple filters are converged into a main feed line, which is then connected to the outlet of the dilution mixer. Similarly, on the slag discharge side, each filter's slag discharge line is equipped with a fifth valve, and all branches converge into a main slag discharge line, ultimately connecting to a slag receiving tank.

[0053] The actual operation of this configuration demonstrates the ingenuity of its design. During normal production, the control system ensures that at least one or more filters are in "filtration" mode, meaning their fourth electric valve is open, receiving dilution bottom oil from the main feed line for filtration, with purified oil exiting from the clear liquid outlet. Simultaneously, the system can designate another filter to be in "backwashing" or "standby" mode. When the differential pressure of an online filter rises to a set value due to filter element blockage, the control system automatically initiates a switching procedure. It first slowly opens the fourth and second electric valves of a standby filter that has already been flushed, allowing it to smoothly enter filtration operation. Then, the system closes the fourth and second electric valves of the filter requiring cleaning, isolating it from the system. Next, it opens the third electric valve on the backwash line of that filter, the first electric valve on the main line, and the fifth electric valve on the slag discharge line, pressurizing the filter. The flushed slag then flows through its fifth electric valve and the main slag discharge line into the slag receiving tank. After flushing, the filter returns to standby mode, awaiting its next commissioning. Through this sequential rotation operation, it can always be ensured that at least one filter is processing the material, thus achieving uninterrupted and continuous purification of the material.

[0054] This configuration, which involves multiple filters operating in parallel and switching them via valve assemblies, delivers crucial technical and economic benefits. Its core advantage lies in completely resolving the conflict between filtration operations and equipment cleaning and regeneration, achieving true 24 / 7 continuous production and significantly enhancing the unit's operational flexibility and overall processing capacity. This is essential for modern large-scale continuous processes, preventing substantial economic losses from production line downtime or shutdowns caused by single-unit equipment maintenance. Simultaneously, this design allows for more thorough and efficient cleaning of each filter, maintaining optimal filter element performance and extending their lifespan. Ultimately, this solution significantly enhances the stability, reliability, and economy of the entire coal-to-oil purification unit and subsequent process systems by improving equipment availability and operational flexibility.

[0055] Although the embodiments of this utility model have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for this utility model. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, this utility model is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A coal-to-oil preparation system, characterized in that, The preparation system is equipped with a vacuum tower bottom oil purification device, which is located at the bottom outlet of the vacuum tower in the preparation system.

2. The preparation system according to claim 1, characterized in that, The vacuum tower bottom oil purification device includes: The dilution mixer has its inlet pipes connected to the bottom outlet pipe of the vacuum distillation tower and a light component solvent delivery pipe, respectively, for mixing and diluting the bottom oil with the light component solvent; The high-precision filter has its inlet connected to the outlet of the dilution mixer via a feed pipe. The high-precision filter has multiple metal sintered membrane filter elements inside. The metal sintered membrane filter elements adopt an outside-to-in filter flow channel. The backflush air inlet of the high-precision filter is connected to a high-pressure air source via a backflush pipe. A first electric valve is installed on the backflush pipe. The slag receiving tank has its inlet connected to the bottom slag discharge port of the high-precision filter via a slag discharge pipeline. It is used to receive the solid slag-containing liquid that is filtered, intercepted, and discharged during backwashing.

3. The preparation system as described in claim 2, characterized in that, Also includes: The slag-liquid treatment unit has its inlet connected to the outlet of the slag receiving tank via a slag-liquid conveying pump; the slag-liquid treatment unit is provided with at least two discharge pipelines: the first discharge pipeline is connected to the upstream coal slurry preparation system, and the second discharge pipeline is connected to a solvent recovery and spray drying device.

4. The preparation system according to claim 2, characterized in that, The filtration accuracy of the metal sintered membrane filter element is 0.05~0.5 micrometers.

5. The preparation system as described in claim 2, characterized in that, The high-precision filter's clear liquid outlet is connected to a purified oil output pipeline, which is used to transport the clean vacuum tower bottom oil after solid removal to the downstream as a high-end raw material. A second electric valve is installed on the purified oil output pipeline.

6. The preparation system according to claim 1, characterized in that, The high-precision filter has probes for differential pressure detection devices located below the tube sheet and below the tube sheet, which are used to automatically trigger the backwashing program when the differential pressure inside and outside the filter element of the high-precision filter reaches a set value.

7. The preparation system according to claim 1, characterized in that, The high-precision filter housing is made of a high-temperature and high-pressure resistant alloy material, with a design operating temperature of 260℃ to 280℃ and a design operating pressure of 1.0MPa to 1.2MPa.

8. The preparation system as described in claim 5, characterized in that, Multiple high-precision filters are provided, and these high-precision filters are connected in parallel: Each high-precision filter is equipped with a third electric valve on its backflush line. The backflush lines of multiple high-precision filters are connected to a main backflush line. The first electric valve is located on the main backflush line. Each high-precision filter is equipped with a fourth electric valve on its feed pipe. The feed pipes of multiple high-precision filters are connected to a main feed pipe, which is connected to the outlet of the dilution mixer. Each high-precision filter is equipped with a fifth valve on its slag discharge pipeline. The slag discharge pipelines of multiple high-precision filters are connected to a main slag discharge pipeline, which is connected to the slag receiving tank.

Images