A catalytic distillation device for recovering heat from raw coal gas and pre-treating coal tar and its application

Abstract

The present invention discloses a catalytic distillation device and application for recovering heat from raw coal gas and pre-treating coal tar. The device comprises a catalytic distillation tower; a raw coal gas mechanical impurity scrubbing zone at the bottom of the catalytic distillation tower; a suspended bed catalytic distillation zone in the middle of the catalytic distillation tower; at least one liquid material outlet is provided in the middle of the catalytic distillation zone from bottom to top. The liquid material outlet is connected to a heat exchanger via a pipeline. After cooling in the heat exchanger, the material is connected to the upper reflux port and an external discharge line of the catalytic distillation tower via a pipeline; the upper reflux port of the catalytic distillation tower is connected to an oil-soluble suspended bed hydrogenation catalyst addition device; and a gaseous material outlet is provided at the top of the catalytic distillation tower. The device of the present invention can simultaneously recover heat from high-temperature raw coal gas and effectively pre-treat coal tar, laying the foundation for subsequent processing.

Description

Technical Field

[0001] The invention relates to a device for recovering heat from raw coal gas and pre-treating coal tar and its application, and belongs to the technical field of preparing liquid hydrocarbon mixture and coal gas from coal. Background Art

[0002] my country's energy resources are unevenly distributed, characterized by "abundant coal, scarce oil, and limited natural gas." Specifically, coal resources are abundant, accounting for 94.3% of proven fossil energy reserves and approximately 70% of total primary energy consumption. Among these abundant coal resources, low-rank coal holds the largest reserves, comprising 55% of proven reserves. While low-rank coal is difficult to utilize directly as fuel, it is a high-quality raw material for producing liquid hydrocarbons from coal.

[0003] There are two main routes to produce liquid hydrocarbons from low-rank coal. One is direct coal liquefaction, which is relatively expensive. The other is coal distillation / coking technology, which relies on the pyrolysis of low-rank coal. This technology is simple and mature, resulting in coke or semi-coke that is a high-quality fuel and reducing agent for the metallurgical industry. Liquid hydrocarbons (i.e., coal tar) are also obtained, which can be further processed to produce liquid fuels and various chemical raw materials.

[0004] During the coal dry distillation / coking process, the temperature of the discharged raw gas is high, generally reaching above 600°C, and generally accounts for about 37% of the heat expenditure of the coke oven; the raw gas has a complex composition, containing solid coke powder, complex mixed hydrocarbons, complex gas phase, water, etc. Although this gas is rich in heat, it is difficult to recycle the heat. The main problems are the blockage, coking, corrosion, etc. of the heat exchange equipment. In traditional technology, ammonia water is used for spraying and cooling, and all the heat in it is lost, and the energy consumption of the device is relatively high. Therefore, how to effectively recover the heat in the raw gas, especially how to solve the problems of equipment blockage and coking when recovering heat, is a key concern in this field.

[0005] CN201410692354.7 discloses a system and method for dust removal and oil cooling of tar from pyrolysis raw gas, comprising a sequentially connected particulate dust collector, an electrostatic precipitator, a tar refining tower, a gas cooling tower, and an electrostatic tar collector. The present invention installs a tar refining tower between the particulate bed dust collector and the gas cooling tower, fully utilizing the heat of the gas itself. The collected tar is further dehydrated and refined using the "distillation principle," resulting in a short process flow and high-quality tar with low moisture content. This solution directly utilizes the sensible heat carried by the pyrolysis gas as a heat source for the distillation of the water-containing tar in the tar refining tower, achieving efficient heat utilization within the same tar recovery system. The goal is to provide a novel heat recovery process and method for pyrolysis raw gas cooling and tar recovery and refining systems. However, this solution utilizes a particulate dust collector and electrostatic precipitator, which, for raw gas prone to coking and the generation of sludge-like solids, can lead to severe equipment fouling and coking, significantly impacting the operating cycle.

[0006] CN201310391012.7 discloses a coke oven raw gas waste heat recovery and utilization system, comprising a heat exchange medium circulation system and a water supply system. The heat exchange medium circulation system includes a heat exchanger group, a steam drum, and a forced circulation pump. The water inlet of the heat exchanger group is connected to the water outlet of the steam drum via the forced circulation pump, and the water outlet of the heat exchanger group is connected to the water inlet of the steam drum. The steam outlet on the steam drum is connected to the external steam pipe network. The water supply system includes a buffer water tank, a water supply pump, a feed water pump, and a desalination and deoxygenation water tank. The feed water pump is arranged between the buffer water tank and the desalination and deoxygenation water tank, and the buffer water tank is connected to the steam drum via the water supply pump. This solution increases the safety and reliability of the heat exchange system by providing multiple parallel heat exchanger groups and adding a control system to detect and handle failures in a heat exchanger group in a timely manner, thereby improving the safe and normal operation of the system and reducing the accident rate. However, due to the characteristics of raw coal gas, coking and fouling of the heat exchanger group will inevitably occur quickly. Even if a parallel method is used, maintenance of one of the groups will still cause large fluctuations and operational difficulties in normal operation.

[0007] CN201610213831.6 discloses a system and method for recovering heat from raw gas using washing and rectification. The raw gas undergoes rectification and washing to remove heavy tar and coke powder, resulting in high-boiling-point oil products and high-temperature raw gas. The high-boiling-point oil products and / or high-temperature raw gas are then heat-exchanged to generate high-pressure steam, which is then separated into steam and water, and the separated steam is utilized. The system boasts high dust removal efficiency, stable operation, resistance to clogging, and allows for full heat recovery. However, the system has the following deficiencies: (1) Although the solid dust is basically removed by washing and the problem of equipment blockage caused by coke powder is solved, the bottom temperature of the washing distillation tower is relatively high, and the problem of high-boiling-point components in the raw gas being easily coked at high temperatures has not been solved, which still affects the operation cycle of the device; (2) Based on the principle of the distillation tower of the plate tower, although a specially structured "flow-through tower plate" is designed (see paragraph 30 of its manual), the coking properties of the material have not changed, and the coking problem will still exist. After the equipment has been running for a certain period of time, the coking problem will inevitably exist; (3) The coking characteristics of the obtained coal tar have not changed, and the problems of coking and equipment blockage in subsequent processing are still prominent.

[0008] CN201911169496.4 discloses a deep desulfurization system and method for coupling coke oven raw gas and coke. By setting up a high-temperature coke hydrogenation reactor, the hydrogenation reaction of coke can be completed by utilizing the H2 rich in the raw gas itself without the need for additional hydrogenation, thereby transferring the sulfur in the coke to the gas; by setting up a catalytic hydrogenation reactor, a catalyst is used to almost completely convert the organic sulfur in the raw gas into H2S, and the organic and inorganic sulfur in the coke oven gas are efficiently and deeply removed from the source, thereby greatly reducing the sulfur content of the coking benzene product and coke, improving the quality of the benzene product and coke, and reducing the load and difficulty of subsequent fine desulfurization. This method is carried out at high temperature (the coal tar component in the raw coal gas is in the gas phase), for example, the hydrogenation reactor should be controlled at 650~1000℃. Under this condition, the coal tar component will be further dehydrogenated (hydrogenation / dehydrogenation is reversible. Under certain conditions, such as low temperature and high pressure, it is mainly hydrogenation, and under certain conditions, such as high temperature and low pressure, it is mainly dehydrogenation), causing hydrocarbons to generate more unsaturated olefins, diolefins, aromatic olefins and other easily coking substances. Not only does it fail to pretreat the coal tar, but it also brings more serious coking problems to the subsequent coal tar processing.

[0009] Although the existing technology has conducted a lot of research on the utilization of raw coal gas heat, its coking characteristics have not been changed, there is no good solution to the coking problem, and the problem of coking affecting the stable operation of the device has not been solved.

[0010] Coal tar is a liquid mixed hydrocarbon recovered from raw coal gas. It has complex components and a significant tendency to coke. The traditional method is to hydrogenate it under mild conditions to saturate the dienes and aromatic groups that are prone to coking, thereby alleviating problems in subsequent processing.

[0011] The unit for recovering coal tar from raw gas is independent of the subsequent processing unit, and needs to go through storage, transportation and other links. In these links, the coal tar coking precursors form preliminary polymerization under the action of oxygen (there is a small amount of nitrogen in the raw gas, and storage and transportation inevitably contact with oxygen) and active sulfur. These preliminary polymers are very easy to form coke when the temperature rises. Therefore, it is difficult to solve the coking problem of coal tar in processing in the later stage and the effect is not ideal.

[0012] CN200710034412.7 discloses a coal tar pretreatment method that removes most impurities from the coal tar by mixing the coal tar with distillate oil and aromatic hydrocarbons, respectively, and performing a two-step extraction process. This method achieves a coal tar utilization rate of 90%. When the pretreated coal tar is hydrogenated to produce fuel oil, it can delay coking of the hydrogenation catalyst and extend the operating cycle of the equipment. However, this method still loses a significant amount of coal tar feedstock during the pretreatment step, and the two-step extraction requires energy-intensive steps such as solvent recovery, resulting in high operating costs.

[0013] CN201010621125.8 discloses a combined hydrogenation method for coal tar and coking distillate, comprising: (1) mixing coal tar feedstock and coking distillate feedstock with hydrogen and entering a hydrogenation pretreatment reactor for a diolefin removal reaction; (2) directly mixing the reaction effluent of the hydrogenation pretreatment reactor with the material heated in a heating furnace from the hydrocracking reaction effluent of step (4) to reach the required temperature at the inlet of the hydrotreating reactor; (3) the reaction effluent of the hydrotreating reactor enters a separation system to separate circulating hydrogen, gasoline fraction, diesel fraction, and heavy oil fraction; (4) the heavy oil fraction from step (3) and circulating hydrogen are mixed and entered into a hydrocracking reactor, and the reaction effluent of the hydrocracking reactor is heated in a heating furnace and directly mixed with the reaction effluent of the hydrogenation pretreatment reactor to enter the hydrotreating reactor. This solution adopts a method of pre-hydrogenating saturated diolefins to solve the coking problem of coal tar and coking distillate hydrotreating units.

[0014] CN200810030954.1 discloses a coal tar hydrogenation process, comprising pre-treating coal tar to obtain a coal tar hydrogenation feed; the resulting coal tar hydrogenation feed enters a pre-hydrogenation fixed-bed reactor from bottom to top; the resulting pre-hydrogenation product oil enters a main hydrogenation fixed-bed reactor from top to bottom; the resulting main hydrogenation product oil enters a fractionation system to obtain gasoline, diesel, and light fuel oil fractions. This scheme employs an upflow pre-hydrogenation fixed-bed reactor in series with a downflow main hydrogenation fixed-bed reactor, changing the flow direction of the process and increasing the residence time of the reactant stream on the catalyst bed. This can effectively inhibit or slow the coking reaction of coal tar at high temperatures and extend the continuous operation cycle of the coal tar hydrogenation unit. In this scheme, the upflow hydrogenation method to alleviate coking is limited in effect and can only have a certain effect on catalyst bed clogging. The problem of coke deactivating the catalyst remains unresolved. Summary of the Invention

[0015] In response to the deficiencies in the prior art, the present invention provides a catalytic distillation device for raw gas heat recovery and coal tar pretreatment. The device of the present invention organically combines the work of raw gas heat recovery and coal tar pretreatment, which are performed in two units in the prior art, into one device. While recovering the raw gas heat, it changes the coking characteristics of the coal tar, ensuring the stable operation of the heat recovery device. At the same time, it effectively pretreats the coal tar for subsequent processing units, effectively solving the coking problem in the subsequent processing of coal tar.

[0016] The present invention relates to a crude gas heat recovery and coal tar pretreatment catalytic distillation device, comprising the following contents:

[0017] (1) Catalytic distillation tower;

[0018] (2) The lower part of the catalytic distillation tower is the raw gas mechanical impurity washing area, and the raw gas inlet is set at the lower part of the mechanical impurity washing area;

[0019] (3) The middle part of the catalytic distillation tower is a suspended bed catalytic distillation zone, and at least one liquid phase material outlet is set from bottom to top in the middle of the catalytic distillation zone. The liquid phase material outlet is connected to the heat exchanger through a pipeline. After cooling in the heat exchanger, the material is connected to the upper reflux port and the external discharge pipeline of the catalytic distillation tower through the pipeline;

[0020] (4) The upper reflux port of the catalytic distillation tower is connected to the oil-soluble suspended bed hydrogenation catalyst adding device;

[0021] (5) A gas phase material outlet is provided at the top of the catalytic distillation tower.

[0022] In the device of the present invention, the catalytic distillation tower is a vertical cylindrical structure and can be designed according to conventional techniques in the art.

[0023] In the apparatus of the present invention, the mechanical impurity scrubbing zone utilizes a spray-type gas-liquid contact element or a tray-type gas-liquid contact element. Since the material within this zone contains mechanical impurities, the gas-liquid contact element must be resistant to clogging, and a spray-type structure is preferred. When a tray-type structure is employed, the tray surface can be designed so that no liquid phase accumulates. Specifically, the downcomer is positioned close to the tray surface, and the gas and liquid phases contact in opposite directions within the downcomer.

[0024] In the device of the present invention, a discharge material pipeline is provided at the bottom of the mechanical impurity washing zone, a circulation pipeline is provided for recycling part of the discharged material back to the mechanical impurity washing zone, and a filtering device is provided for removing mechanical impurities from the discharged material and / or the circulating material.

[0025] In the apparatus of the present invention, the suspended bed catalytic distillation zone utilizes either a tray-type gas-liquid contact element or a packed gas-liquid contact element. A liquid collection device is provided at the liquid-phase material outlet of the suspended bed catalytic distillation zone. For tray-type gas-liquid contact elements, a liquid collection trough can be provided at the edge of the tray; for packed gas-liquid contact elements, a liquid collection plate or other component is required. The above design can be based on conventional techniques in the art.

[0026] In the device of the present invention, the heat exchanger can be any structure of a shell-and-tube heat exchanger, a spiral tube heat exchanger, or a plate heat exchanger, and can be designed according to conventional techniques in the art.

[0027] The present invention provides an application of a raw gas heat recovery and coal tar pretreatment catalytic distillation device. The raw gas derived from a coking device or a coal dry distillation device directly enters a catalytic distillation tower, and coal tar pretreatment and fractionation are performed while heat is recovered.

[0028] In the application of the present invention, the coking device or coal dry distillation device is a device that uses coal as raw material, performs heat treatment, and produces coke, semi-coke, and by-products coal tar and coal gas. The raw coal gas temperature is 450-850°C, preferably 600-800°C.

[0029] In the present invention, the operating temperature of the mechanical impurity scrubbing zone is 350-550°C, preferably 380-500°C, and most preferably 400-450°C. The operating temperature is controlled by introducing aqueous ammonia into the zone. The concentration of the introduced aqueous ammonia can be any, preferably 30%-70% saturation at room temperature.

[0030] In the application of the present invention, the catalytic distillation tower is operated under normal pressure.

[0031] In the application of the present invention, the temperature of the liquid phase material withdrawn from the catalytic distillation zone is 250-450°C, preferably 300-400°C. The liquid phase material may be withdrawn in one or several streams. When withdrawing multiple streams, a corresponding reflux operation may be provided to achieve preliminary fractionation of the coal tar during pretreatment. The distillation accuracy (number of plates) and number of withdrawn streams in the catalytic distillation zone can be comprehensively designed as needed, which is conventional in the art.

[0032] In the application of the present invention, the operating temperature at the top of the catalytic distillation tower is above 110° C., preferably 110-250° C., and most preferably 120-150° C. The principle of controlling the top operating temperature is to prevent water vapor from condensing and liquefying in the catalytic distillation tower.

[0033] In the application of the present invention, an oil-soluble suspension bed hydrogenation catalyst is added to the reflux material at the top of the catalytic distillation column. The suspension bed hydrogenation catalyst contains at least one element from Group VIB and Group VIII of the Periodic Table. The suspension bed hydrogenation catalyst is a material containing at least one of cobalt, molybdenum, nickel, tungsten, and iron. The amount of the suspension bed hydrogenation catalyst additive added, based on element weight, is 5 to 5000 μg / g, preferably 10 to 2000 μg / g, and most preferably 50 to 500 μg / g. The oil-soluble suspension bed hydrogenation catalyst is one or more organic compounds containing cobalt, molybdenum, nickel, tungsten, and iron.

[0034] The oil-soluble suspended bed hydrogenation catalyst can be any product known in the art, such as those disclosed in CN01106013.1, CN201410216485.8, CN202010553349.3, CN201711137478.9, and CN201811388624.X. The advantage of an oil-soluble suspended bed hydrogenation catalyst is that it does not adversely affect the operation of the distillation zone. The catalyst should be highly active, require minimal dosage, be low cost, and have minimal impact on subsequent processing. Furthermore, the catalyst should not vaporize under the conditions of the catalytic distillation zone and remain in the liquid phase.

[0035] In the application of the present invention, the material discharged from the top of the catalytic distillation tower is further cooled to recover light hydrocarbons and coal gas.

[0036] The present invention aims to recover the heat of raw gas while pre-treating coal tar, and achieves the following technical effects: (1) The heat recovery of raw gas is organically coupled with the pre-treatment of coal tar, which changes the existing method of pre-treating in the subsequent coal tar processing unit, realizes synchronous pre-treatment in coal tar recovery, solves the stable operation problems such as coking of the heat recovery device of raw gas, and solves the problem of aggravated coking caused by the formation of coking precursors in the section between coal tar recovery and subsequent processing, and simplifies the process and equipment of the subsequent processing unit; (2) A catalytic distillation method is adopted, in which "catalysis" uses an oil-soluble suspended bed hydrogenation catalyst, which has no effect on "distillation". The oil-soluble suspended bed hydrogenation catalyst is added from the top of the tower and runs from the top to the bottom of the tower in the distillation tower operation mode. The utilization rate of the catalyst is high, and the catalytic effect occurs continuously from the top of the tower (low temperature) to the bottom of the tower (high temperature). It is beneficial to give full play to the activity of the catalyst, reduce the usage, and have an outstanding effect on the hydrogenation pretreatment of coal tar, solve the coking problem of distillation towers and heat exchangers, and can ensure long-term and high-efficiency operation; (3) Although suspended bed hydrogenation is a relatively weak method of hydrogenation, before the coal tar forms coking precursors during subsequent storage and transportation, simple suspended bed hydrogenation can effectively hydrogenate dienes and aromatic groups, which is easier and more effective than the coal tar hydrogenation unit; (4) The process is simple, utilizing the state and properties of coal tar in raw gas and the hydrogen present in raw gas, and realizing multiple functions such as heat recovery, coal tar recovery, coal tar pre-hydrogenation treatment, and coal tar pre-fractionation in one process, which is conducive to reducing equipment investment; (5) Although the suspended bed hydrogenation process and catalyst belong to the existing technology in this field, its main application purpose is to hydrocracking heavy hydrocarbons to obtain light hydrocarbon products. Since the hydrogenation efficiency of the suspended bed hydrogenation technology is relatively low, there is no existing technology that uses suspended bed hydrogenation for the pretreatment of coal tar. Moreover, in the method of the present invention, the suspended bed hydrogenation is not directly used for the pretreatment of the recovered coal tar, but the pretreatment is carried out at the same time as the heat recovery in the coal tar recovery process. Moreover, because the pretreatment before the initial formation of the coking polymerization precursors during processing, storage and transportation and the fouling and coking on the surface of the heat exchanger are avoided, a better pretreatment result is achieved with a poor hydrogenation effect. (6) An appropriate amount of ammonia water is introduced into the mechanical impurity washing zone, and the temperature is appropriately lowered. The alkalinity of ammonia is conducive to suppressing the polymerization and coking tendency of the coking precursors in the high-temperature raw coal gas, which solves the problem that the high-boiling point components in the raw coal gas are easy to coke at high temperatures to a certain extent, thereby ensuring the operation cycle of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The present invention is a schematic structural diagram of the raw gas heat recovery and coal tar pretreatment catalytic distillation device. DETAILED DESCRIPTION

[0038] The present invention will be further described below through specific embodiments, but the protection scope of the present invention is not limited thereto.

[0039] In the present invention, raw coal gas is extracted from a coking device or a coal dry distillation device. The coking device or the coal dry distillation device can be any technology currently available in the art. Coking generally refers to high-temperature coking, and the temperature can reach 900-1100°C. Dry distillation includes medium-temperature dry distillation (660-750°C), low-temperature dry distillation (500-580°C), etc. Coal is heated and decomposed in an airtight condition to produce coke (or semi-coke), coal tar, crude benzene, coal gas and other products.

[0040] The temperature of high-temperature raw coal gas is related to the operating temperature and process of the coking unit or coal distillation unit, but in general it is a high-temperature, easily coked material.

[0041] In the present invention, since most of the heat is recovered in the external heat exchange process during the catalytic distillation process, the amount of ammonia water required in the subsequent steps is greatly reduced.

[0042] To illustrate the effectiveness of the present invention, a method for testing the coking characteristics of a material is described as follows: a material and porous ceramic beads (volume ratio of 3:1) are placed in a high-temperature stirred tank and maintained at a specific temperature and pressure for a specified period of time. The toluene-insoluble matter is then collected, and the relative amount of this matter is used as the material's coking property. A larger relative amount indicates a greater tendency for the material to coke. The toluene-insoluble matter collection process consists of two steps: The toluene-insoluble matter in the liquid phase is measured according to GB / T 2292-1997; and the toluene-insoluble matter on the porous ceramic beads is determined by thoroughly rinsing them with toluene. The insoluble matter in the toluene-insoluble matter is then collected, and the weight gain of the porous ceramic beads is measured. The sum of these toluene-insoluble matter is the total toluene-insoluble matter.

[0043] Example 1

[0044] A crude gas heat recovery, coal tar pretreatment catalytic distillation device (such as Figure 1 ), 1 is the catalytic distillation tower, 2 is the raw gas inlet, 3 is the bottom material discharge pipeline, 4 is the bottom material circulation pipeline, 5 is the liquid material outlet, 6 is the external heat exchanger, 7 is the reflux material pipeline, 8 is the material discharge pipeline after heat exchange, 9 is the oil-soluble suspended bed hydrogenation catalyst introduction device, and 10 is the tower top gas phase discharge pipeline.

[0045] Comparative Example 1

[0046] A coal tar processing enterprise purchases medium- and low-temperature coal tar, which is the processing enterprise's conventional coal tar raw material Z1.

[0047] Example 2

[0048] The raw gas of a certain enterprise, with a temperature of about 600℃, directly enters the structure Figure 1The catalytic distillation tower shown in the figure has a bottom temperature controlled at 520°C by injecting aqueous ammonia. The mechanical impurity scrubbing zone is a spray-type structure, and a portion of the bottom material is circulated to maintain a liquid-to-gas ratio of 100 L / cubic meter of gas (based on the inlet). The catalytic distillation zone is packed with packing according to 10 theoretical fractionation stages. A liquid collection tray is installed at a liquid temperature of approximately 350°C. The temperature of the liquid phase removed is controlled at 350°C. After removal, heat is recovered by heat exchange to a temperature of 130°C, partially discharged, and partially recycled to the top of the tower, where the top temperature is controlled at 135°C. An oil-soluble suspended bed hydrogenation catalyst (Example 1 of CN01106013.1) is added to the top of the tower at a metal element weight of 400 μg / g (based on the sum of the mass of the liquid phase discharged from the bottom of the catalytic distillation tower and the mass of the liquid phase discharged from the catalytic distillation zone, excluding any reflux, which is the basis for all calculations in this invention).

[0049] The exhaust phase outside the top of the catalytic distillation tower is cooled to 80°C by spraying with ammonia water, and then light coal tar and coal gas are recovered.

[0050] Heavy coal tar A2 is discharged from the bottom of the tower (after filtration), medium coal tar B2 is discharged from the catalytic distillation zone, and light coal tar C2 is recovered from the exhaust gas phase at the top of the tower. The mixed sample of the three (according to the output ratio) is D2.

[0051] Comparative Example 2

[0052] Referring to the reaction conditions of the method in Example 2, conventional coal tar Z1 was used as the raw material for hydrogenation reaction, with an external hydrogen source, a hydrogen-to-oil volume ratio of 600:1 (under standard conditions), a temperature of 350°C, and the catalyst and dosage were as in Example 2. The reaction product was collected to obtain coal tar Z2.

[0053] Example 3

[0054] The coking characteristics of coal tar obtained in the Examples and Comparative Examples were tested. Conditions: temperature 350°C, nitrogen pressure to 8 MPa (gauge pressure), high-pressure stirred tank, 30 minutes. The collected toluene-insoluble matter was calculated as a percentage of the weight of the feed (relative value, with Z1 as 100%).

[0055]

Claims

1. A catalytic distillation device for heat recovery of raw coal gas and pretreatment of coal tar, comprising the following: (1) Catalytic distillation tower; (2) The lower part of the catalytic distillation tower is a raw gas mechanical impurity washing area, and a raw gas inlet is provided at the lower part of the mechanical impurity washing area; (3) The middle part of the catalytic distillation tower is a suspended bed catalytic distillation zone, and at least one liquid material outlet is provided in the middle of the catalytic distillation zone from bottom to top. The liquid material outlet is connected to a heat exchanger through a pipeline. After cooling in the heat exchanger, the material is connected to the upper reflux port and the external discharge pipeline of the catalytic distillation tower through a pipeline; (4) the upper reflux port of the catalytic distillation tower is connected to the oil-soluble suspended bed hydrogenation catalyst adding device; (5) A gas phase material outlet is provided at the top of the catalytic distillation tower.

2. The device according to claim 1, characterized in that: The catalytic distillation tower is a vertical cylindrical structure.

3. The device according to claim 1, characterized in that: The mechanical impurity washing area adopts a spray type gas-liquid contact component or a tray type gas-liquid contact component.

4. The device according to claim 1 or 3, characterized in that: A material discharge pipeline is provided at the bottom of the mechanical impurity washing area, and a circulation pipeline is provided for circulating part of the discharged material back to the mechanical impurity washing area.

5. The device according to claim 4, characterized in that: A filtering device is provided to remove mechanical impurities from discharged materials and / or recycled materials.

6. The device according to claim 1, characterized in that: The suspended bed catalytic distillation zone adopts a tray type gas-liquid contact component or a packing type gas-liquid contact component.

7. The device according to claim 1, characterized in that: A liquid collecting device is provided at the liquid phase material outlet of the suspended bed catalytic distillation zone.

8. The device according to claim 1, characterized in that: The heat exchanger can be any structure of a shell and tube heat exchanger, a spiral tube heat exchanger, or a plate heat exchanger.

9. An application of the crude gas heat recovery and coal tar pretreatment catalytic distillation device according to claim 1, characterized in that: The raw gas from the coking unit or coal dry distillation unit is directly fed into the catalytic distillation tower, where coal tar pretreatment and fractionation are performed while heat is recovered.

10. The use according to claim 9, characterized in that: The coking device or coal dry distillation device is a device that uses coal as raw material, performs heat treatment, produces coke and semi-coke, and produces coal tar and coal gas as by-products.

11. The use according to claim 9 or 10, characterized in that: The raw gas temperature is 450~850℃.

12. The use according to claim 11, characterized in that: The raw gas temperature is 600-800℃.

13. The use according to claim 9, characterized in that: The operating temperature of the mechanical impurity washing zone is 350-550℃.

14. The use according to claim 13, characterized in that: The operating temperature of the mechanical impurity washing zone is 380-500℃.

15. The use according to claim 13, characterized in that: The operating temperature of the mechanical impurity washing zone is 400-450℃.

16. The use according to claim 13, characterized in that: The operating temperature is controlled by introducing ammonia water into the mechanical impurity washing area.

17. The use according to claim 9, characterized in that: The catalytic distillation tower is operated under normal pressure.

18. The use according to claim 9, characterized in that: The temperature of the liquid phase material drawn out from the catalytic distillation zone is 250-450°C.

19. The use according to claim 18, characterized in that: The temperature of the liquid phase material drawn out from the catalytic distillation zone is 300-400°C.

20. The use according to claim 9, characterized in that: The operating temperature at the top of the catalytic distillation tower is above 110°C.

21. The use according to claim 20, characterized in that: The operating temperature at the top of the catalytic distillation tower is 110-250°C.

22. The use according to claim 20, characterized in that: The operating temperature at the top of the catalytic distillation tower is 120-150°C.

23. The use according to claim 9, characterized in that: An oil-soluble suspension bed hydrogenation catalyst is added to the reflux material at the top of the catalytic distillation tower. The suspension bed hydrogenation catalyst contains at least one element from Group VIB and Group VIII of the periodic table.

24. The use according to claim 23, characterized in that: The suspended bed hydrogenation catalyst is a substance containing at least one element among cobalt, molybdenum, nickel, tungsten and iron.

25. The use according to claim 23, characterized in that: The amount of the suspended bed hydrogenation catalyst additive added is 5 to 5000 μg / g based on element weight.

26. The use according to claim 25, characterized in that: The amount of the suspended bed hydrogenation catalyst additive added is 10 to 2000 μg / g based on element weight.

27. The use according to claim 25, characterized in that: The amount of the suspended bed hydrogenation catalyst additive added is 50 to 500 μg / g based on element weight.

28. The use according to claim 23, characterized in that: The oil-soluble suspended bed hydrogenation catalyst is one or more organic compounds containing cobalt, molybdenum, nickel, tungsten and iron.

29. The use according to claim 9, characterized in that: The material discharged from the top of the catalytic distillation tower is further cooled to recover light hydrocarbons and coal gas.

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