Coal pyrolysis tar recovery method and system

Abstract

The present application relates to a coal pyrolysis tar recovery method and system, which passes oil mist and raw coal gas into a washing tower to make the oil mist and raw coal gas directly contact with washing oil for cooling, separates to obtain liquid phase coal tar and gas phase medium, and then the gas phase medium is sequentially cooled by an air cooler and a condenser to separate oil and water, the liquid phase solid-containing coal tar is fine filtered from outside to inside by a 0.1 micron metal sintered membrane filter under the condition of 260-280 DEG C and 1.0-1.2 MPa, the filter residue is discharged through a pressurized residue discharge valve, and the solid-removed coal tar is recovered by decompression fractionation to obtain washing oil and pure coal tar. By controlling the cooling temperature of the liquid phase coal tar to be 110-120 DEG C and using specific filtering parameters, the micron-level solid particles in the high-temperature viscous medium are efficiently removed. The method is suitable for efficient recovery of coal pyrolysis tar, the obtained washing oil can be recycled, and the pure coal tar can be directly used as fuel or chemical raw material.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coal pyrolysis. More particularly, the present application relates to a coal pyrolysis tar recovery method and system. BACKGROUND

[0002] Coal pyrolysis technology is the core driving force of efficient utilization of coal, solving the pain points of each link in the whole process of coal pyrolysis technology is the breakthrough to promote the development of coal pyrolysis technology, and forms the coordinated development of the upstream and downstream of the industrial chain.

[0003] Coal tar, as one of the important products of coal pyrolysis, as a high value-added oil product, its deep processing mainly uses hydrogenation device to produce light fuel (such as gasoline and diesel oil), which can greatly improve the economic benefit. At present, the cooling method after coal pyrolysis is water washing, the coal pyrolysis temperature is 600~800℃, a large amount of water is consumed during cooling, and a large amount of water vapor is also generated during the pyrolysis process, the coal tar after cooling contains a large amount of water and organic matters such as phenols, part of the organic matters is weakly acidic, and long-term operation corrodes the equipment. The existing technology uses extraction or oil-water separation, but the organic matters in the water cannot be completely purified, especially the phenols cannot be separated out, which will cause a large amount of contaminated water discharge and greatly damage the environment.

[0004] Coal tar contains a large amount of solid particles, and the viscosity is large, which causes problems such as pipeline blockage due to solid settlement during transportation. At present, the coal tar desolidification technology basically adopts centrifugation, sedimentation or addition of reagents, but the coal tar solid particle removal rate is not high, especially some particles below 5 microns. And the existing filter device basically blocks after three months due to poor filter core regeneration effect. The desorption rate cannot reach the requirement, which will cause the catalyst coking of the downstream hydrogenation device, the activity decreases, the pressure drop increases, and the device cannot run for a long period. Therefore, the coal tar desolidification technology is the key process restricting the sustainable development of the current industrial chain, and it is urgent to solve it. SUMMARY

[0005] The purpose of the present application is to provide a coal pyrolysis tar recovery method and system to at least solve the above problems.

[0006] In order to achieve the purpose and other advantages of the present application, a coal pyrolysis tar recovery method is provided, which comprises the following steps: coal is pyrolyzed at high temperature in a reaction furnace to generate coke, oil mist and raw coal gas; the oil mist and the raw coal gas are introduced into a washing tower to directly contact with washing oil for cooling, and liquid phase coal tar and gas phase medium are separated; the gas phase medium is sequentially cooled by a first-stage air cooler and a second-stage condenser, and then subjected to oil-water separation treatment to obtain low-boiling-point organic matter and purified water; the liquid phase coal tar is transported to a filter to remove solid particles; the desolidified coal tar is introduced into a washing oil vacuum tower for fractionation, washing oil vapor is collected from the top of the tower, condensed and recovered to a washing oil storage tank, and the bottom purified coal tar is transported to a coal tar storage tank or a downstream device.

[0007] The temperature of the liquid-phase coal tar after cooling is controlled at 110-120℃; the filter adopts a 0.1-micron metal sintered membrane filter element, the operating temperature of the filter is 260-280℃, the operating pressure is 1.0-1.2 MPa, and the filtering operation includes: delivering the coal tar containing solids at the tower bottom to the filter, filtering from the outside to the inside through the metal sintered membrane filter element, when the solid accumulation on the surface of the metal sintered membrane filter element reaches a set thickness, pressurizing the space above the filter tube plate to a set pressure value, then opening the deslagging valve to discharge the solid particles accumulated on the surface of the metal sintered membrane filter element to the downstream deslagging tank.

[0008] Preferably, the reaction furnace adopts a vertical continuous pyrolysis reaction furnace; the coal is first screened and crushed to control the particle size of the coal particles in the range of 5-20 mm, and then the screened and crushed coal is uniformly fed into the reaction furnace at a speed of 5-15 tons / hour through a sealed feeding device; the high-temperature pyrolysis process in the reaction furnace is divided into three stages: a preheating stage: the temperature in the furnace is raised from room temperature to 200-300℃ within 10-15 minutes through a burner to inject high-temperature combustion gas at the bottom of the furnace, and the water and part of the volatile substances in the coal begin to separate out; a rapid pyrolysis stage: after the preheating stage ends, the supply of combustion gas is increased to rapidly raise the temperature in the furnace to 500-600℃ within 20-30 minutes, and at the same time, the stirring equipment in the reaction furnace is started to rotate at a speed of 15-20 revolutions / minute to continuously turn the coal particles to ensure uniform heating of the coal, at this time, the coal undergoes intense pyrolysis reaction, and a large amount of oil mist and raw coal gas is generated; a deep pyrolysis stage: after the rapid pyrolysis stage ends, the supply of combustion gas is reduced to maintain the temperature in the furnace at 600-800℃ for 30-40 minutes to fully pyrolyze the organic substances in the coal to generate more coke, oil mist and raw coal gas.

[0009] Preferably, the washing tower adopts circulating wash oil as the cooling medium, which is introduced from a wash oil storage tank and delivered to the washing tower through a wash oil pump to directly contact and countercurrently cool the oil mist and raw coal gas, and the initial boiling point of the wash oil is 230-300℃; a flow regulating valve is arranged at the wash oil inlet of the washing tower to control the flow of the wash oil into the washing tower by adjusting the opening of the flow regulating valve; the specific way to control the temperature of the liquid-phase coal tar after cooling at 110-120℃ is to arrange a first temperature sensor at the liquid-phase coal tar outlet of the washing tower, which is connected to a control system, when the first temperature sensor detects that the temperature of the liquid-phase coal tar is higher than 120℃, the control system controls the flow regulating valve to increase the opening to increase the flow of the wash oil into the washing tower to enhance the cooling effect; when the first temperature sensor detects that the temperature of the liquid-phase coal tar is lower than 110℃, the control system controls the flow regulating valve to decrease the opening to reduce the flow of the wash oil into the washing tower to reduce the cooling effect.

[0010] Preferably, the condenser adopts a spiral plate condenser, and the cooling medium is a mixed medium of circulating cooling water and chilled water; a second temperature sensor is arranged on the outlet pipeline of the condenser to monitor the temperature T c of the gaseous medium in real time after cooling c , and the opening of the chilled water proportioning valve is dynamically adjusted by the control system to make T c stabilize in the range of 50-60℃; the oil-water separation treatment adopts a three-stage coalescence separation device, which is internally provided with a hydrophobic and oleophilic fiber filler layer and a corrugated plate coalescence assembly; the control system is configured with a temperature-viscosity compensation module, and when T

[0013] >60℃ is detected, the electric field intensity of the three-stage coalescence separation device is adjusted to 2-3kV / cm, and the separation chamber pressure is controlled to be 0.05-0.1MPa.

[0011] Preferably, the hydrophobic and oleophilic fiber filler layer adopts a gradient density structure design, which is divided into three layers from top to bottom, the top layer is a polytetrafluoroethylene fiber woven mesh with a pore size of 8-12μm and a porosity of 85%-90%, the middle layer is a polypropylene fiber bundle loaded with a nano-silicon dioxide coating with a fiber spacing of 0.3-0.5mm, and the bottom layer is a three-dimensional corrugated structure composed of carbon fibers and glass fibers with a corrugation angle of 45°-60°; the plate spacing of the corrugated plate coalescence assembly is 10-15mm, the surface is provided with a micro-groove array with a depth of 0.2-0.3mm, and the direction of the micro-groove array is at an angle of 30° to the direction of the medium flow.

[0012] Preferably, when the solid accumulation thickness on the surface of the metal sintering coated filter element reaches 3-5mm, high-pressure nitrogen gas is introduced into the space above the filter tube plate to pressurize the space above the filter tube plate, and when the pressure reaches the set value, the downstream quick-opening backflushing and deslagging valve is opened, the solid particles on the surface of the metal sintering coated filter element are quickly separated from the metal sintering coated filter element under the action of pressure difference, the filter is emptied, and then the quick-opening backflushing and deslagging valve is closed to complete the regeneration process of the metal sintering coated filter element.

[0013] Preferably, the de-solidified coal tar is continuously fed into the middle feeding port of the wash oil vacuum tower through a preheated screw conveyor at 210-230 DEG C, the four-stage fractionation section is arranged in the wash oil vacuum tower, and the light wash oil trapping section, the main fractionation section, the heavy component buffer section and the tower bottom heat circulation section are arranged from top to bottom; the light wash oil trapping section is operated at an absolute pressure of 15-25 kPa, the three-layer inclined baffle tray is arranged in the light wash oil trapping section, the microporous distributor with a pore size of 0.8-1.2 mm is arranged on the tray surface, and the top temperature of the light wash oil is controlled at 85-95 DEG C through the external condenser; the main fractionation section is filled with regularized stainless steel corrugated packing, the specific surface area of the packing is 450-500 m² / m³, the distributed temperature sensor array is arranged in the main fractionation section, the axial temperature gradient is monitored in real time, and the vacuum tower top pressure is fed back and adjusted, so that the temperature gradient is maintained at 12-15 DEG C / m; the tower bottom heat circulation section is configured with a double-channel heat medium heating system, wherein the main channel adopts heat conduction oil circulation heating to maintain the tower bottom temperature at 195-205 DEG C, and the auxiliary channel dynamically compensates the temperature fluctuation through the steam ejector, and the steam injection is automatically started to reduce the viscosity when the detected tower bottom viscosity exceeds 300 mPa·s.

[0014] Preferably, after the wash oil vapor is taken out from the top of the wash oil vacuum tower, the wash oil vapor is first introduced into a primary condenser to exchange heat with circulating cooling water at 30-40 DEG C, so that the temperature of the wash oil vapor is reduced to 80-90 DEG C; then the wash oil vapor is introduced into a secondary condenser to exchange heat with frozen brine at 5-10 DEG C in a spiral pipe process countercurrently, so that the wash oil vapor is further cooled to 40-50 DEG C and completely liquefied and then transported to a wash oil storage tank; wherein the primary condenser adopts a corrugated plate fin structure, and the heat exchange surface is coated with a graphene-titanium dioxide composite anti-coking coating; the inner wall of the spiral pipe process of the secondary condenser is provided with a spiral micro groove with a depth of 0.3-0.4 mm and a groove spacing of 2-3 mm.

[0015] The application also provides a coal pyrolysis tar recovery system for realizing the coal pyrolysis tar recovery method.

[0016] The application at least has the following beneficial effects:

[0017] First, by using the direct contact countercurrent cooling of oil mist and raw gas with washing oil, and controlling the cooling temperature of liquid phase coal tar at 110-120℃, this temperature setting can avoid the liquefaction of a large amount of water vapor generated in the pyrolysis process, so that the low-boiling-point organic matter and water vapor are separated from the coal tar in the gas phase, and when the subsequent condensation temperature is controlled at 50-60℃, the water can be discharged without pollution through oil-water separation. The second is that the washing oil can be used as a solvent for coal tar to dissolve the asphaltene and other substances with high viscosity in the coal tar, so as to reduce the viscosity of the coal tar, so that the subsequent filtration system can realize liquid-solid separation and can operate for a long period. Using a 0.1 micron metal sintered membrane filter element, the filtration is carried out from the outside to the inside at 260-280℃ and 1.0-1.2 MPa, combined with pressurized deslagging operation, which can effectively intercept submicron solid particles (such as coke powder, carbon black), while using high temperature to reduce the viscosity of the tar to reduce the adhesion on the surface of the filter element, significantly improve the filtration efficiency, and the solid content of the purified coal tar is not more than 50 ppm. The segmented pressurized deslagging design realizes filter cake peeling through dynamic pressure adjustment, avoiding the residue problem of traditional gravity deslagging, prolonging the service life of the filter element to more than 2000 hours, and reducing the precision decay rate to less than 2% per month. Compared with the method of increasing reagents to realize coal tar solid separation, this method is purely physical, avoiding the influence of increasing reagents on downstream catalysts, while the operation cost and energy consumption are greatly reduced.

[0018] Second, use a vertical continuous pyrolysis reaction furnace and control the temperature in stages (preheating, rapid pyrolysis, and deep pyrolysis), combined with coal particle size control and uniform feeding, so that the coal particles are heated more uniformly, reducing the coking or incomplete cracking caused by local overheating. Through the stirring equipment, the coal bed is turned at 15-20 revolutions per minute, effectively breaking the material bonding layer formed during pyrolysis, and increasing the release rate of oil mist and raw gas by 15%-20%. The staged temperature rising strategy (200-300℃ preheating, 500-600℃ rapid pyrolysis, 600-800℃ deep pyrolysis) matches the coal pyrolysis kinetics, and the coke yield is stabilized at 65%-70%, while the content of non-target components such as CO in the raw gas is reduced to less than 5%.

[0019] Third, by controlling the first temperature sensor and the flow regulating valve, combined with the reasonable selection of the initial boiling point of the washing oil (230-300℃), the high-boiling-point tar components can be preferentially condensed during the cooling process, reducing the escape of light oil mist.

[0020] Fourth, the spiral plate condenser combined with mixed cooling medium (circulating water + chilled water), through the fourth temperature sensor linkage to adjust the proportion of chilled water, so that the temperature of the gas phase medium is stable at 50-60℃ interval, the condensation efficiency of low boiling point organic matter is improved to 98.5%. The three-stage coalescence separation device uses electric field strengthening (2-3kV / cm) and pressure synergistic control, and the separation efficiency of oil droplets with particle size >5μm is 99.9%, and the oil content in the effluent is <50mg / L. The temperature-viscosity compensation module adjusts the separation chamber pressure (0.05-0.1MPa) in real time, effectively inhibits the oil-water emulsification phenomenon at high temperature, and reduces the COD value of wastewater to below 3000mg / L.

[0021] Fifth, the gradient density hydrophobic oleophilic filler layer intercepts large particle size oil droplets through the top layer of PTFE fiber mesh (porosity 85%-90%), the middle layer of nano-SiO2 coated polypropylene fiber bundle (spacing 0.3-0.5mm) adsorbs submicron oil mist, and the bottom layer of three-dimensional corrugated structure (inclination angle 45°-60°) prolongs the oil-water contact time, and the comprehensive separation efficiency is improved by 12%-15%. The corrugated plate micro-groove array (0.2-0.3mm deep, 30° included angle) induces droplet collision and coalescence, so that the average particle size of oil droplets increases from the initial 50μm to more than 300μm, and the coalescence time is shortened to 1 / 3 of that of traditional fillers. The carbon fiber-glass fiber composite structure can withstand a temperature of 150℃, and the service life is extended to more than 5 years.

[0022] Sixth, the four-stage fractionation section design combined with reduced pressure operation (15-25kPa) improves the separation efficiency of the washing oil and heavy component tar to 99.2%, and the content of heavy components (>300℃) in the washing oil is ≤0.5%. The regular filler (specific surface area 450-500m² / m³) and distributed temperature monitoring work together, the axial temperature gradient control precision is ±0.5℃ / m, and the washing oil distillation range (initial boiling point-dry point) is narrowed to within 20℃. The double-channel heating system (heat conducting oil + steam injection) stabilizes the viscosity at the tower bottom to 200-250mPa·s, the steam injection compensation response time is ≤10 seconds, and the heat cycle energy consumption is reduced by 18%.

[0023] Seventh, two-stage condenser staged cooling (80-90℃→40-50℃) combined with graphene-titanium dioxide anti-coking coating makes the washing oil vapor condensation efficiency reach 99.8%, and the coking rate is reduced to below 0.1g / (m²·h). The spiral micro-groove (0.3-0.4mm deep, 2-3mm spacing) strengthens the turbulent effect, and the heat transfer coefficient is improved to 3500W / (m²·K), and the chilled brine consumption is reduced by 25%. The water content in the completely liquefied washing oil is <0.1%, which can be directly used for washing tower, and the annual recycling rate is ≥99.5%.

[0024] Other advantages, objects, and features of the application will be apparent to those skilled in the art from the following specification. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a flow diagram of a coal pyrolysis tar recovery method in one embodiment of the present application.

[0026] Figure 2 is a connection structure diagram of a coal pyrolysis tar recovery system in another embodiment of the present application. DETAILED DESCRIPTION

[0027] The present application will be further described with reference to the following examples and drawings, which are intended to illustrate the present application and not to limit the same.

[0028] It should be understood that the terms such as "have", "contain", and "include" used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0029] It should be noted that the experimental methods described in the following embodiments are all conventional methods, and the reagents and materials are commercially available unless otherwise specified; in the description of the present application, the terms "lateral", "longitudinal", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0030] As Figure 1As shown, in one embodiment of the present application, a coal pyrolysis tar recovery method is provided, which comprises the following steps: pyrolyzing coal at high temperature in a reaction furnace (reactor in the figure) to generate coke, oil mist and raw coal gas; passing the oil mist and raw coal gas into a washing tower to directly contact the oil mist and raw coal gas with washing oil for cooling to separate liquid phase coal tar (coal tar in the figure) and gas phase medium (water vapor and low boiling point organic matter in the figure); sequentially cooling and condensing the gas phase medium through an air cooler and a condenser to separate oil and water to obtain low boiling point organic matter and purified water; conveying the liquid phase coal tar to a filter to remove solid particles; and conveying the solid particle removed coal tar into a washing oil vacuum tower for fractionation, recovering washing oil vapor after condensation to a washing oil storage tank, and conveying clean coal tar (clean coal tar in the figure) at the bottom of the tower to a coal tar storage tank or a downstream device; wherein the temperature of the liquid phase coal tar after cooling is controlled at 110-120℃; the filter uses a 0.1 micron metal sintered membrane filter element, the operating temperature of the filter is 260-280℃, the operating pressure is 1.0-1.2 MPa, and the filtering operation comprises: conveying the solid particle containing coal tar at the bottom to the filter, filtering from the outside to the inside through the metal sintered membrane filter element, when the solid accumulation on the surface of the metal sintered membrane filter element reaches a set thickness, pressurizing the space above the filter tube plate to a set pressure value, then opening the deslagging valve to discharge the solid particles accumulated on the surface of the metal sintered membrane filter element to a downstream deslagging tank (filter residue tank in the figure), the mixture of solid particles and washing oil in the deslagging tank can separate the washing oil in a downstream flash tank, and the solid enters a dryer for drying.

[0031] In the above technical solution, the specific value of the cooling temperature of the liquid phase coal tar can be set to 112℃, 115℃ or 118℃, and the temperature control accuracy is ±2℃. The washing tower can be a packed tower with a diameter of 3.2 meters and a height of 18 meters, which is internally provided with 50mm metal Baohua ring packing, and a washing oil distributor is arranged at the top of the tower. The temperature control is realized by adjusting the washing oil circulation amount, and the washing oil can be selected from anthracene oil fractions with a flash point of 230℃. A liquid level meter and a temperature sensor linkage control system are arranged at the bottom of the washing tower, and when the liquid phase temperature exceeds 120℃, the washing oil spraying amount is automatically increased. The matching washing oil circulating pump can be selected from an IH type chemical centrifugal pump with a motor power of 55kW.

[0032] In the above technical solution, the filtering accuracy of the metal sintered membrane filter element can be selected to be 0.1 micron, the filter element base material can be selected from 316L stainless steel, and the surface membrane can be selected from 316L stainless steel. The filter shell can be selected from Q345R or Luomo steel, and the design pressure is 1.5MPa. The filter is installed horizontally after the elbow of the outlet pipeline of the washing tower bottom. The filtering pressure is adjusted by a pressure reducing valve, and a pressure transmitter can be selected from a Rosemount 3051 type with a range of 0-2.5MPa, which is installed at the top of the inlet pipeline of the filter. Similar equipment configuration can be found in the catalytic cracking oil slurry filtering system in the petrochemical industry.

[0033] In the above technical solution, the pressure setting value of the pressurized deslagging can be 1.3 MPa, 1.5 MPa or 1.7 MPa, and the pressurizing medium can be nitrogen. The deslagging valve can be a ball valve or a three-eccentric butterfly valve, and the valve body material can be WCB, which is installed on the filter bottom deslagging port flange. The pressure difference trigger threshold is set to 0.35 MPa, and the pressure difference between the inside and outside of the filter core is monitored in real time by a pressure difference transmitter (range 0-0.6 MPa). The deslagging duration can be set to 45 seconds, 60 seconds or 75 seconds, and the valve is closed after deslagging is completed. The similar deslagging method can refer to the automatic backflushing design of the coal chemical black water filtering system.

[0034] Through the above embodiment, the liquid phase coal tar cooling temperature fluctuation range is reduced from ±10℃ to ±2℃. The metal sintering coated filter core has a 99.8% interception efficiency on particles above 0.5 microns under a 270℃ working condition, and the filter core flux retention rate is improved from a monthly decrease of 5% to within 2%.

[0035] In another embodiment of the present application, the reaction furnace is a vertical continuous pyrolysis reaction furnace. Before entering the reaction furnace, the coal is first screened and crushed to control the particle size of the coal particles in the range of 5-20 mm. Then, the screened and crushed coal is uniformly fed into the reaction furnace through a sealed feeding device at a feeding speed of 5-15 tons / hour. The high-temperature pyrolysis process in the reaction furnace is divided into three stages: preheating stage: the bottom of the reaction furnace is injected with high-temperature combustion gas through a burner to raise the temperature in the furnace from room temperature to 200-300℃ within 10-15 minutes, and the water content and part of the volatile matter in the coal begin to separate out; rapid pyrolysis stage: after the preheating stage ends, the gas supply is increased to rapidly raise the temperature in the furnace to 500-600℃ within 20-30 minutes, and the stirring equipment in the reaction furnace is started to rotate at a speed of 15-20 revolutions / minute to continuously turn the coal particles and ensure uniform heating of the coal. At this time, the coal undergoes intense pyrolysis reaction, and a large amount of oil mist and raw gas is generated; deep pyrolysis stage: after the rapid pyrolysis stage ends, the gas supply is reduced to maintain the temperature in the furnace at 600-800℃ for 30-40 minutes to fully pyrolyze the organic matter in the coal and generate more coke, oil mist and raw gas.

[0036] In the above technical solution, in the coal pretreatment stage, the particle size of the crushed coal particles can be selected as 8 mm, 12 mm or 18 mm, and the qualified rate of the particle size is required to be ≥95%. The screening equipment can be selected as a double-layer vibrating screen (screen mesh diameter 5 mm and 20 mm), and the crusher can be selected as a double-roller crusher (roller surface material is high chromium cast iron). The sealed feeding device can be selected as a rotary valve feeder (pass DN300), the valve body material is 16MnR, and is installed 1.2 meters above the feeding port flange on the top of the reaction furnace. The feeding speed can be adjusted by a variable frequency motor, the motor power can be selected as 22 kW or 37 kW, and the speed control accuracy is ±1%. The similar pretreatment process can refer to the particle size control process of the coal blending system of the coking plant.

[0037] In the above technical solution, when the temperature in the reaction furnace is controlled in stages, the temperature in the preheating stage can be set to 220°C, 250°C or 280°C, and the temperature rising rate is controlled at 15-20°C / min. The gas supply amount adjusting valve in the rapid pyrolysis stage can be selected as a pneumatic diaphragm adjusting valve (stroke accuracy ±0.5%), and the burner can be selected as a swirl type gas nozzle (material 310S stainless steel) installed on the bottom of the reaction furnace. The temperature in the deep pyrolysis stage is maintained by circulating the heat conducting oil in the jacket, the temperature of the heat conducting oil in the jacket can be set to 620°C, 650°C or 680°C, and the oil pump flow is controlled to 30-50 m³ / h. The temperature sensor can be selected as a K-type thermocouple array arranged at 1 / 4, 1 / 2 and 3 / 4 of the height direction of the inner wall of the reaction furnace with a spacing of 1.5 meters. The similar temperature control mode can be found in the heating furnace partition control of the delayed coking device.

[0038] In the above technical solution, the stirring equipment can be selected as a planetary gear reducer motor (output torque 1200-1500 N·m), the stirring shaft material is 35CrMo alloy steel, and the blade can be selected as a 2520 heat-resistant steel casting installed at the central axis position inside the reaction furnace. The stirring speed can be set to 16 rpm, 18 rpm or 19 rpm, and the accuracy control is ±0.5 rpm through the frequency converter. The gap between the blade and the furnace wall can be set to 80 mm, 100 mm or 120 mm, and the installation position is calibrated by a laser centering instrument. The stirring power consumption monitoring can be realized by a motor current sensor, and the current fluctuation range is controlled within ±5% of the rated value. The similar stirring structure can refer to the mechanical stirring design of the fluidized bed reactor.

[0039] Through the above-mentioned embodiments, the coal particle pyrolysis uniformity index is improved from 0.35 to 0.82 (index range 0-1), the coke yield fluctuation range is reduced from ±8% to ±2.5%, the CO content in the raw coal gas is reduced from 7%-9% to 4.2%-4.8%, the H2 and CH4 effective component proportion is improved to 78%-82%, the stirring equipment operation energy consumption is reduced by 15%-18%, the blade wear rate is reduced from 2mm per month to 0.5mm per month, the reaction furnace unit processing capacity is improved from 8 tons / hour·cubic meter to 11 tons / hour·cubic meter, the pyrolysis oil mist generation rate is stabilized at 1.2-1.5 tons / hour, the system continuous operation cycle is extended from 30 days to 65 days, and the emergency shutdown frequency is reduced by 80%.

[0040] In another embodiment of the present application, the washing tower uses circulating wash oil as the cooling medium. The circulating wash oil is drawn from the wash oil storage tank and delivered to the washing tower by a wash oil pump for direct contact countercurrent cooling of the oil mist and the raw coal gas. The initial boiling point of the wash oil is 230-300 DEG C. A flow regulating valve is arranged at the wash oil inlet of the washing tower, and the flow of the wash oil into the washing tower is controlled by adjusting the opening of the flow regulating valve. The specific way to control the temperature of the liquid phase coal tar after cooling at 110-120 DEG C is to arrange a first temperature sensor at the liquid phase coal tar outlet of the washing tower. The first temperature sensor is connected to a control system. When the first temperature sensor detects that the temperature of the liquid phase coal tar is higher than 120 DEG C, the control system controls the flow regulating valve to increase the opening, increases the flow of the wash oil into the washing tower, and enhances the cooling effect. When the first temperature sensor detects that the temperature of the liquid phase coal tar is lower than 110 DEG C, the control system controls the flow regulating valve to decrease the opening, reduces the flow of the wash oil into the washing tower, and reduces the cooling effect.

[0041] In the above technical solution, the initial boiling point of the wash oil can be selected from three subintervals of 230-250 DEG C, 260-280 DEG C or 290-300 DEG C, and the wash oil with an initial boiling point of 260-280 DEG C is preferably selected to improve the condensation efficiency of high-boiling-point components. The circulating wash oil can come from the wash oil storage tank and be delivered to the cooling system by a centrifugal pump. The wash oil storage tank can be made of carbon steel lined with 316L stainless steel with a temperature resistance range of -20 DEG C to 350 DEG C. The wash oil flow is adjusted by a variable frequency pump, and the flow control range is 10-50 m³ / h. After heat exchange, the wash oil can be pre-cooled by a plate heat exchanger with circulating water before returning to the storage tank to reduce the temperature fluctuation of the storage tank.

[0042] In the above technical solution, the first temperature sensor can be a armored Pt100 thermal resistance, installed on the flange of the liquid outlet pipeline of the washing tower 300mm upstream of the straight pipe section. The control system can use DCS or PLC (such as Siemens S7-1500), with a built-in fuzzy PID algorithm module. When the temperature exceeds 120℃, the opening of the flow regulating valve (such as ZFQ47H-16C) is increased by 5%~10%, corresponding to an increase of 15~20m³ / h in the washing oil flow; when the temperature is lower than 110℃, the opening is reduced by 3%~8%, and the flow is reduced by 10~15m³ / h. The response time of the regulating valve is ≤2 seconds, and the valve body material is WCB+STL alloy plating, with a pressure rating of PN16.

[0043] This embodiment optimizes the initial boiling point (260~280℃) to increase the condensation rate of high-boiling tar components to 92%~95%, and reduce the light oil mist escape amount by 18%~22%. Closed-loop temperature control stabilizes the viscosity of the liquid phase coal tar at 220~280mPa·s (test standard: GB / T 265), and reduces the pressure drop of the conveying pipeline to 0.3~0.5MPa. Dynamic balance valve and first temperature sensor cooperate to control the temperature fluctuation range from ±10℃ of the traditional process to ±2℃. The equipment structure design effectively prevents coking, and the continuous operation period is extended from 120 hours to more than 240 hours.

[0044] In another embodiment of the present application, the condenser uses a spiral plate condenser, and the cooling medium is a mixture of circulating cooling water and chilled water; a second temperature sensor is provided on the outlet pipeline of the condenser to monitor the temperature T c of the gas phase medium after cooling in real time, and the opening of the chilled water proportioning valve is dynamically adjusted by the control system to stabilize T c in the range of 50-60℃; the oil-water separation treatment uses a three-stage coalescence separation device, which is internally provided with a hydrophobic oleophilic fiber filler layer and a corrugated plate coalescence assembly; the control system is provided with a temperature-viscosity compensation module, which adjusts the electric field strength of the three-stage coalescence separation device to 2-3kV / cm and controls the separation chamber pressure to 0.05-0.1MPa when T c >60℃ is detected.

[0045] In the above technical solution, the spiral plate condenser can be selected with a double spiral channel structure, the cooling medium channel width is 10-15 mm, the spiral body material is 316L stainless steel, and the thickness is 2.5-3 mm. The volume ratio of circulating water to chilled water in the mixed cooling medium is adjusted in the range of 1:1 to 3:1, and dynamic proportioning can be realized through a proportional adjusting valve (such as Honeywell VF34). The second temperature sensor can be selected as a PT100 thermal resistance, installed 500 mm downstream of the condenser outlet pipe flange, and the monitoring temperature threshold is set to 50°C (lower limit) and 60°C (upper limit). When the detected temperature Tc>60°C, the control system can increase the chilled water proportion to 70%-80%; when Tc<50°C, the chilled water proportion is reduced to 20%-30%. The chilled water supply system can be integrated with an industrial water chiller (such as the Teling CVHE series), and the circulating water is taken from the cooling pond return water system. The installation position of the spiral plate condenser is located downstream of the air cooler, and is connected with the gas phase medium pipe through a flange.

[0046] In the above technical solution, the first stage of the three-stage coalescing separation device can be configured with a polytetrafluoroethylene fiber woven mesh with a pore size of 8-12 μm (porosity 85%-90%), the second stage uses a polypropylene fiber bundle loaded with nano-silicon dioxide coating (fiber spacing 0.3-0.5 mm), and the third stage uses a carbon fiber and glass fiber composite corrugated structure (inclination angle 45°-60°). The electric field intensification assembly can be selected with a plate electrode structure, the electrode spacing is set to 3-5 mm, the working voltage range is 2-3 kV / cm, and the electrode material is titanium alloy plated with platinum. The plate spacing of the corrugated plate coalescing assembly is 10-15 mm, the surface micro-groove depth is 0.2-0.3 mm, and it is formed by numerical control milling. The pressure control module can include a pneumatic regulating valve (such as Fisher GX3) and a pressure transmitter (such as Rosemount 3051), installed at the top exhaust pipe of the separation device, with a pressure control accuracy of ±0.01 MPa. Experimental data shows that when the oil droplet particle size is >5 μm, the separation efficiency can reach 99.9%, and the oil content in the effluent is controlled at 40-48 mg / L (test standard: GB / T 17930).

[0047] In the above technical solution, the temperature-viscosity compensation module can be integrated with an online viscometer (such as Brookfield DV3T) and a pressure feedback controller. The viscosity measurement range is set to 50-500 mPa·s, when the medium viscosity is detected to be >200 mPa·s, the separation chamber pressure is automatically increased to 0.08-0.1 MPa; when the viscosity is <100 mPa·s, the pressure is reduced to 0.05-0.07 MPa. The pressure adjustment response time is ≤5 seconds, and closed-loop control is achieved through a PID algorithm (such as Siemens PID Compact module). The separation chamber shell is made of 304 stainless steel, the design pressure is 0.15 MPa, and the safety valve take-off pressure is set to 0.12 MPa. Actual operation data shows that after using this module, the wastewater COD value is reduced from 3500 mg / L to 2800-2950 mg / L (test method: HJ828-2017).

[0048] This embodiment achieves a low-boiling-point organic matter condensation efficiency of 98.5% through the double-channel design of the spiral plate condenser (cooling efficiency increased by 18%-22%) and precise regulation of the mixed medium (temperature fluctuation ±1.5°C). The three-stage coalescence separation device combines electric field enhancement (energy consumption reduced by 15%-20%) and gradient density filler layer to achieve an oil-water separation efficiency of 99.9% and an oil content in the effluent of <50 mg / L. The temperature-viscosity compensation module effectively suppresses high-temperature emulsification through dynamic pressure adjustment (response time ≤3 seconds), and the wastewater COD value is stabilized in the range of 2900-3050 mg / L. After 200 days of continuous operation of the system, the performance degradation rate of the key components (electrode plate, fiber filler) is <3%, and the maintenance cycle is extended to 180 days.

[0049] In another embodiment of the present application, the hydrophobic and oleophilic fiber filler layer is designed in a gradient density structure, which is divided into three layers from top to bottom. The top layer is a polytetrafluoroethylene fiber woven mesh with a pore size of 8-12 μm and a porosity of 85%-90%. The middle layer is a polypropylene fiber bundle loaded with nano-silicon dioxide coating, with a fiber spacing of 0.3-0.5 mm. The bottom layer is a three-dimensional corrugated structure composed of carbon fiber and glass fiber, with a corrugation angle of 45°-60°. The plate spacing of the corrugated plate coalescence assembly is 10-15 mm, and the surface is provided with a micro-groove array with a depth of 0.2-0.3 mm. The direction of the micro-groove is at an angle of 30° to the direction of medium flow.

[0050] In the above technical solution, the PTFE fiber mesh can be selected from polytetrafluoroethylene woven filter cloth with porosity of 88-89% (such as Saint-Gobain Norton® PTFE mesh), pore size range of 8-10 μm, thickness of 1.2-1.5 mm, and installed in the upper frame of the three-stage separation device. The middle layer fiber bundle can be made of polypropylene filaments with a diameter of 0.5 mm (such as RM-FB40 type of Rongmao Company), coated with a nano-SiO2 coating layer (particle size of 20-50 nm, such as Aladdin S143909) by sol-gel method, and the fiber spacing is controlled at 0.35-0.45 mm. The mesh-like structure is formed by cross-winding through a weaving machine and installed in the middle support plate. The bottom layer wave structure is made of carbon fiber (Toray T300) and E glass fiber (Jushi Group ER-388) mixed at a ratio of 3:1, the wave inclination angle is selected as 50°-55°, and the wave depth is 8-10 mm. The wave structure is made by hot pressing process and installed 200 mm above the lower water collecting tank. After the gradient structure is assembled, water test is required to verify the pressure drop of each layer, and the pressure drop gradient should meet the threshold requirements of top layer <0.05 MPa, middle layer <0.08 MPa, and bottom layer <0.12 MPa.

[0051] In the above technical solution, the corrugated plate can be made of 316L stainless steel stamping (such as Ximeiya SP-202 type), the micro-groove depth is selected as 0.25-0.28 mm, the groove spacing is 2.0-2.5 mm, and the parallel groove array with a 30° inclination angle is processed by numerical control milling machine. When installed, the groove direction should be at an angle of 28°-32° with the medium flow direction, and arranged in the middle of the separation chamber, 1.2-1.5 m away from the inlet pipe. Experimental data shows that when the initial particle size of oil droplets is 40-60 μm, the average particle size can reach 280-320 μm after 3-5 times of groove collision, and the coalescence time is shortened from 18-22 seconds of traditional fillers to 6-8 seconds. Regular laser profilometer (such as Keyence LJ-V7000) is required to detect the groove depth wear, and the corrugated plate needs to be replaced when the depth attenuation reaches 0.15 mm.

[0052] In the above technical solution, the carbon fiber-glass fiber composite support frame is made of mixed filaments with a diameter of 0.8-1.2 mm (such as mixed filaments of Toray T700S and Jushi ER-220), and the wave plate fixing support is made by molding process. The tensile strength retention rate should be ≥95% after 150℃, 5000 hour accelerated aging test for temperature resistance test. High-temperature resistant rubber gasket (such as DuPont Kalrez® 6375) is required to be installed at the bottom of the separation device to compensate for the thermal expansion difference. Actual operation data shows that after continuous use in oily wastewater (oil content of 500-800 mg / L) environment for 5 years, the material surface corrosion rate is <0.02 mm / year, which is significantly better than the corrosion rate of 0.12 mm / year of traditional 304 stainless steel.

[0053] The embodiment achieves the comprehensive oil-water separation efficiency of 98.2%-98.7% through the three-layer gradient structure (PTFE interception efficiency of 92%-94%, SiO2 / PP fiber adsorption rate of 89%-91%, and corrugated structure retention time extended to 18-22 seconds), which is 12%-15% higher than that of the traditional single-layer filler. The corrugated plate micro-groove design makes the oil droplet coalescence speed increase to 3.1-3.3 times of that of the traditional filler, and the treatment capacity increases to 25-30 m³ / h. The carbon fiber-glass fiber composite frame has a structure deformation amount of less than 0.5 mm after continuous operation for 180 days under the working condition of 150 DEG C, and the service life verification can reach 5.2-5.5 years. The energy consumption of the whole device is reduced to 0.8-1.2 kW·h / m³, which is 18%-20% lower than that of the traditional process.

[0054] In another embodiment of the application, when the solid accumulation thickness on the surface of the metal sintered coated filter element reaches 3-5 mm, high-pressure nitrogen gas is introduced into the space above the filter tube plate, the space above the filter tube plate is pressurized, when the pressure reaches the set value, the downstream quick-opening backwashing and deslagging valve is opened, the solid particles on the surface of the metal sintered coated filter element are quickly separated from the metal sintered coated filter element under the action of pressure difference, the filter is discharged, the valve is closed, and the regeneration process of the metal sintered coated filter element is completed.

[0055] In the above technical solution, in terms of solid accumulation thickness monitoring trigger conditions, the set threshold of the solid accumulation thickness on the surface of the metal sintered coated filter element is 3 mm, 4 mm or 5 mm. Laser ranging sensors or ultrasonic thickness gauges can be used for real-time monitoring, and the sensors can be installed inside the filter close to the filter element. The probe emitting end of the sensor is kept 20-50 mm apart from the outer surface of the filter element, and the accumulation thickness is calculated by the time difference of the reflected signal. When the thickness reaches the set value, the sensor sends an electrical signal to the control system to trigger the subsequent operation. The sensor shell can be made of 316L stainless steel, and the working temperature range of the internal electronic components should cover 260-300 DEG C.

[0056] In the above technical solution, in terms of high-pressure nitrogen gas pressurization and deslagging valve control, the set pressure value of the space above the filter tube plate is 1.8 MPa, 2.0 MPa or 2.2 MPa. A high-pressure nitrogen gas pipeline with a nominal diameter of DN50 can be connected to the filter, and an electromagnetic control valve and a pressure transmitter are installed on the pipeline. The nitrogen source can be a high-pressure gas cylinder group with a volume of 40 L, and the working pressure range is 15-25 MPa. The deslagging valve can be a pneumatic quick-opening ball valve, the valve body material can be WCB cast steel, and the sealing element can be made of polytetrafluoroethylene. When the system receives the thickness alarm signal, the filter feed valve is first closed, the nitrogen inlet valve is opened after a delay of 5-10 seconds, and the deslagging valve is quickly opened within 0.5 seconds when the pressure transmitter displays the set value.

[0057] In the above technical solution, in terms of the filter core regeneration operation process, the opening time of the quick-opening backwash and deslagging valve is maintained at 3-5 seconds, and the deslagging valve is closed after deslagging is completed. A differential pressure sensor can be arranged to confirm the deslagging effect, and when the pressure difference between the inlet and outlet of the filter decreases to below 0.05 MPa, it is determined that the deslagging is complete. The discharged solid particles enter the deslagging tank through the guide groove inclined by 60°, and the inner wall of the guide groove can be sprayed with a tungsten carbide wear-resistant coating. After deslagging is completed, the system automatically resumes feeding, and the filtering efficiency of the filter core recovers to more than 95% of the initial state. The deslagging tank can be provided with a weighing module, and when the cumulative weight reaches a set value, a deslagging reminder is issued.

[0058] The embodiment can effectively remove the accumulated material on the surface of the filter core, maintain stable operation of the filtering system, and prolong the service life of the filter core. By accurately controlling the deslagging triggering conditions and operation parameters, the unplanned downtime can be reduced. Standard industrial components are used, which is beneficial to equipment maintenance and spare part replacement. The nitrogen backwashing mode avoids material pollution and ensures stable quality of coal tar.

[0059] In another embodiment of the present application, the desolidified coal tar is continuously fed into the middle feeding port of the wash oil vacuum tower through a preheated spiral conveyor at 210-230 DEG C. The wash oil vacuum tower is provided with four-stage fractionation sections, which are light wash oil trapping section, main fractionation section, heavy component buffer section and tower bottom heat circulation section from top to bottom. The light wash oil trapping section is operated at an absolute pressure of 15-25 kPa, and is provided with three-layer inclined baffle plates, and the surface of the baffle plates is provided with microporous distributors with a pore size of 0.8-1.2 mm. The top temperature of the light wash oil is controlled at 85-95 DEG C through an external condenser. The main fractionation section is filled with regularized stainless steel corrugated packing, and the specific surface area of the packing is 450-500 m2 / m3. The main fractionation section is provided with a distributed temperature sensor array, which monitors the axial temperature gradient in real time and feeds back to adjust the vacuum tower top pressure, so that the temperature gradient is maintained at 12-15 DEG C / m. The tower bottom heat circulation section is provided with a double-channel heat medium heating system, in which the main channel adopts heat conduction oil circulation heating to maintain the tower bottom temperature at 195-205 DEG C, and the auxiliary channel dynamically compensates the temperature fluctuation through a steam ejector, which is automatically started to reduce the viscosity when the detected tower bottom viscosity exceeds 300 mPa·s.

[0060] In the above technical solution, the operating pressure of the vacuum tower can be selected from three typical values of 18 kPa, 20 kPa or 22 kPa, and 20 kPa ± 2 kPa is preferably selected to balance the separation efficiency and energy consumption. The light wash oil trapping section can be configured with three layers of inclined baffle plates (such as Sulzer Mellapak Plus type), the plate spacing is set to 300-400 mm, the plate surface microporous distributor aperture is selected to be 1.0 ± 0.1 mm, and the material is 316L stainless steel. The regular packing in the main fractionating section can be selected from metal wire mesh corrugated packing (such as Koch-Glitsch Flexipac HC series) with a specific surface area of 480 m² / m³, the packing layer height is designed to be 2.5-3.0 m per section, and the material is 304 stainless steel. The heavy component buffer section is installed at a position 1.5-2.0 m above the tower bottom, configured with a flow guide cone structure (cone angle 60°-75°), and the material is 310S heat-resistant steel. The heat conduction oil circuit of the double-channel heating system in the tower bottom heat circulation section is designed to have a temperature of 200 ± 5 °C, and the steam injection pressure is set to 0.6-0.8 MPa.

[0061] In the above technical solution, the distributed temperature sensor array can be selected from K-type armored thermocouples (OMEGA TJ36-CAXL series), with one group arranged every 1 m along the tower height direction, a total of 15-20 groups. The axial temperature gradient control is realized through a PID controller (SIMATIC PCS7 of Siemens), when it is detected that the temperature deviation of a certain section exceeds ± 0.8 °C / m, the corresponding section of the heat conduction oil flow (adjustment range 5%-10%) or the steam injection amount (adjustment range 3-5 kg / h) is automatically adjusted. The temperature sensor installation position needs to avoid the packing support ring and the liquid distributor, and is arranged in the tower wall temperature measuring sleeve 200 mm above the packing layer. Experimental data shows that after using the configuration, the wash oil distillation range (initial boiling point-dry point) is narrowed from 28-35 °C of the traditional process to 18-20 °C (test standard: GB / T 6536).

[0062] In the above technical solution, the heat conduction oil main channel can be selected from Dowtherm A type heat conduction oil, the circulating pump is selected from a high-temperature resistant centrifugal pump (such as Grundfos CRN series), the flow control range is 50-80 m³ / h, and the heating power is 500-800 kW. The steam injection compensation system can be configured with a pneumatic control valve (Fisher GX3) and a Venturi mixer (Schutte & Koerting type), and the response time is set to be ≤8 seconds. When it is detected that the tower bottom viscosity exceeds 250 mPa·s, the steam injection amount is dynamically adjusted at a ratio of 0.5-1.0 kg / (m³·s). The double-system collaborative control realizes data interaction through the OPC protocol, and the tower bottom temperature fluctuation is controlled within ± 3 °C. Actual operation data shows that the configuration reduces the heat circulation energy consumption from the benchmark value of 45 kW·h / t to 36.5-37.8 kW·h / t.

[0063] The embodiment stabilizes the heavy component content in the washing oil at 0.4%-0.48% by a four-stage fractionation structure (99.1%-99.3% recovery rate of the capture stage, 18-20 pieces / m of the theoretical plate number of the main fractionation stage). The structured packing (specific surface area 485 m² / m³) combined with axial temperature control (gradient deviation ±0.3 ℃ / m) narrows the washing oil distillation range to 19-21 ℃. The double-channel heating system (thermal oil heat load 500 kW±5%, steam compensation response time 7-9 seconds) controls the viscosity at the bottom of the tower to 230-245 mPa·s, and the heat cycle energy consumption is reduced by 17.5%-18.2%. After 180 days of continuous operation, the pressure drop of the packing increases by ≤0.05 kPa / m, and the attenuation rate of the system separation efficiency is <0.3%.

[0064] In another embodiment of the application, after the washing oil vapor is taken out from the top of the washing oil vacuum tower, it is first introduced into a primary condenser to exchange heat indirectly with 30-40 ℃ circulating cooling water, so that the temperature of the washing oil vapor is reduced to 80-90 ℃; then it is introduced into a secondary condenser to exchange heat countercurrently with 5-10 ℃ chilled brine in the spiral pipe section, so that the washing oil vapor is further cooled to 40-50 ℃ and completely liquefied, and then transported to a washing oil storage tank; wherein the primary condenser adopts a corrugated plate fin structure, and the heat exchange surface is coated with a graphene-titanium dioxide composite anti-coking coating; the inner wall of the spiral pipe section of the secondary condenser is provided with a spiral micro-channel with a depth of 0.3-0.4 mm and a channel spacing of 2-3 mm.

[0065] In the above technical solution, the primary condenser can adopt a corrugated plate fin structure (such as GEA Varicond series), the cooling medium is selected to be 30-40 ℃ circulating cooling water, the inlet temperature threshold is set to be 85±5 ℃, and the heat exchange area is configured to be 80-120 m². The graphene-titanium dioxide anti-coking coating can be selected to be sprayed by a plasma spraying process, the coating thickness is 20-30 μm, the graphene doping ratio is 3-5%, and the coating is applied to the inner wall of the primary condenser pipe section. The secondary condenser adopts a spiral pipe structure (such as Alfa Laval CBXP series), the temperature of the chilled brine is set to be 5-8 ℃, the depth of the micro-channel on the inner wall of the pipe section is 0.35±0.05 mm, and the channel spacing is 2.5±0.2 mm. The anti-coking coating needs to be tested for coking rate before installation, the test conditions are that the temperature of the washing oil vapor is 120 ℃ and the flow rate is 1.5 m / s, and the coking rate threshold is ≤0.1 g / (m²·h).

[0066] In the above technical solution, the spiral micro-channel can be processed by numerical control milling (such as DMG MORI machine tool), the channel inclination is 30-45°, and the channel section is V-shaped or U-shaped. The micro-channel reinforced turbulent flow effect needs to be optimized by computational fluid dynamics (CFD) simulation, and the Reynolds number is controlled in the range of 5000-8000. The heat transfer coefficient can be measured by the steady-state method, the frozen salt water flow is set to 10-15 m³ / h during testing, the temperature difference ΔT is 35-40℃, and the heat transfer coefficient threshold is ≥3500 W / (m²·K). The spiral pipe material can be selected from 316L stainless steel, the wall thickness is 2.0-2.5 mm, and the channel direction needs to be ensured to be at an angle of 30° with the medium flow direction during installation, and arranged at the inlet section of the secondary condenser pipe for 1-2 m.

[0067] In the above technical solution, the water content of the washing oil can be detected by an online infrared moisture meter (such as Mettler Toledo HX204), which is installed 500 mm downstream of the outlet pipeline of the secondary condenser, and the detection accuracy is ±0.02%. The circulating washing oil storage tank is provided with a nitrogen sealing system, and the oxygen content is controlled to be ≤50 ppm to prevent oxidation of the washing oil. The amount of frozen salt water can be adjusted by a proportional integral valve (such as Fisher GX3), and the salt water mixture ratio is dynamically adjusted according to the outlet temperature of the condenser. The salt water amount threshold is reduced by 25% (from 20 m³ / h to 15 m³ / h). The annual recycling rate is calculated based on the ratio of the annual replenishment amount of the washing oil (≤0.5%) to the total storage amount of the system (such as 500 m³).

[0068] The embodiment makes the comprehensive condensation efficiency of the washing oil vapor reach 99.6-99.8% through two-stage condensation (the first-stage efficiency is 98.2%, and the second-stage efficiency is 99.5%), and the measured value of the coking rate is 0.08-0.095 g / (m²·h). The amount of frozen salt water is reduced from the reference value of 24 m³ / h to 18 m³ / h by the spiral micro-channel (the heat transfer coefficient is 3520-3650 W / (m²·K)) combined with the anti-coking coating (the service life is ≥5 years). The water content of the washing oil is stabilized at 0.07-0.09%, and the annual recycling rate is ≥99.5%. After the system is continuously operated for 180 days, the coating wear rate is <0.5 μm / thousand hours, and the maintenance period is extended to 24 months.

[0069] As shown in Figure 2 The present application also provides a coal pyrolysis tar recovery system for realizing the above-mentioned coal pyrolysis tar recovery method. Among them, Figure 2 The slag receiving tank in Figure 1 corresponds to the slag filtering tank in Figure 2 The washing oil tank in Figure 1 corresponds to the washing oil storage tank in

[0070] The number of units and the scale of processing described herein are used to simplify the description of the application. It will be apparent to those skilled in the art that the application can be practiced with application, modification and variation of the coal pyrolysis tar recovery method and system described herein.

[0071] While embodiments of the application have been disclosed in connection with the specified embodiments, as exemplified in the description and drawings, it should be understood that other embodiments can be implemented without departing from the general nature of the application. Therefore, although the application has been described in connection with particular embodiments, it is to be understood that modifications and variations can be utilized that are not specifically described, but would be within the scope of the claims and their equivalents.

Claims

1. A method for recovering coal pyrolysis tar, characterized by, The method comprises the following steps: Pyrolysis of coal in a reaction furnace to generate coke, oil mist and raw coal gas; The oil mist and raw coal gas are introduced into a washing tower to directly contact with washing oil for cooling, and liquid phase coal tar and gas phase medium are separated; The gas phase medium is sequentially cooled by a first-stage air cooler and a second-stage condenser, and then subjected to oil-water separation treatment to obtain low-boiling-point organic matter and purified water; The liquid phase coal tar is transported to a filter to remove solid particles; The coal tar after solid removal is introduced into a washing oil vacuum tower for fractionation, washing oil vapor is collected at the top of the tower, condensed and then recovered to a washing oil storage tank, and clean coal tar is collected at the bottom of the tower and transported to a coal tar storage tank or a downstream device; The temperature of the liquid phase coal tar after cooling is controlled at 110-120℃; the filter adopts a 0.1-micron metal sintered membrane filter element, the operating temperature of the filter is 260-280℃, the operating pressure is 1.0-1.2 MPa, and the filtering operation comprises the following steps: the coal tar containing solids at the bottom is transported to the filter, filtered from the outside to the inside through the metal sintered membrane filter element, when the solid accumulation on the surface of the metal sintered membrane filter element reaches a set thickness, the space above the tube sheet of the filter is pressurized to a set pressure value, and then the deslagging valve is opened to discharge the solid particles accumulated on the surface of the metal sintered membrane filter element to a downstream deslagging tank; The reaction furnace adopts a vertical continuous pyrolysis reaction furnace; before entering the reaction furnace, the coal is subjected to screening and crushing treatment to control the particle size of the coal particles in the range of 5-20 mm, and then the screened and crushed coal is uniformly fed into the reaction furnace through a sealed feeding device at a feeding speed of 5-15 tons / hour; the high-temperature pyrolysis process in the reaction furnace comprises the following three stages: a preheating stage: the bottom of the reaction furnace is provided with a burner to spray high-temperature combustion gas, so that the temperature in the furnace is increased from room temperature to 200-300℃ within 10-15 minutes, and the water content and part of the volatile matter in the coal begin to be separated; a rapid pyrolysis stage: after the preheating stage is completed, the supply amount of the combustion gas is increased to rapidly increase the temperature in the furnace to 500-600℃ within 20-30 minutes, and a stirring device in the reaction furnace is started to rotate at a speed of 15-20 revolutions / minute to continuously turn the coal particles to ensure uniform heating of the coal, at this time, the coal undergoes intense pyrolysis reaction, and a large amount of oil mist and raw coal gas is generated; a deep pyrolysis stage: after the rapid pyrolysis stage is completed, the supply amount of the combustion gas is reduced to maintain the temperature in the furnace at 600-800℃ for 30-40 minutes to fully pyrolyze the organic matter in the coal to generate more coke, oil mist and raw coal gas; The circulating washing oil is used as the cooling medium of the washing tower, the circulating washing oil is introduced from the washing oil storage tank, and is transported to the washing tower through the washing oil pump to perform direct contact countercurrent cooling on the oil mist and the raw coal gas, the initial distillation point of the washing oil is 230-300 DEG C, a flow regulating valve is arranged at the washing oil inlet of the washing tower, and the flow of the washing oil into the washing tower is controlled by adjusting the opening degree of the flow regulating valve, and the temperature of the liquid phase coal tar after cooling is controlled at 110-120 DEG C, the specific mode is that a first temperature sensor is arranged at the liquid phase coal tar outlet of the washing tower, the first temperature sensor is connected with the control system, when the first temperature sensor detects that the temperature of the liquid phase coal tar is higher than 120 DEG C, the control system controls the flow regulating valve to increase the opening degree, the flow of the washing oil into the washing tower is increased, and the cooling effect is enhanced, and when the first temperature sensor detects that the temperature of the liquid phase coal tar is lower than 110 DEG C, the control system controls the flow regulating valve to decrease the opening degree, the flow of the washing oil into the washing tower is reduced, and the cooling effect is reduced; The condenser adopts a spiral plate type condenser, and its cooling medium is a mixed medium of circulating cooling water and chilled water; a second temperature sensor is arranged on an outlet pipeline of the condenser to monitor the temperature T of the gaseous medium after cooling in real time c , and the opening of a chilled water proportioning valve is dynamically adjusted by a control system to make T c stable in the range of 50-60℃; the oil-water separation treatment adopts a three-stage coalescence separation device, which is internally provided with a hydrophobic oleophilic fiber filler layer and a corrugated plate coalescence assembly; the control system is provided with a temperature-viscosity compensation module, and when T c >60℃ is detected, the electric field intensity of the three-stage coalescence separation device is adjusted to 2-3kV / cm, and the separation chamber pressure is controlled to 0.05-0.1MPa.

2. The coal pyrolysis tar recovery method according to claim 1, wherein The hydrophobic oleophilic fiber filler layer adopts a gradient density structure design, is divided into three layers from top to bottom, the top layer is a polytetrafluoroethylene fiber woven mesh with a pore size of 8-12 mu m and a porosity of 85%-90%, the middle layer is a polypropylene fiber bundle loaded with nano-silicon dioxide coating, and the fiber spacing is 0.3-0.5 mm, and the bottom layer is a three-dimensional corrugated structure composed of carbon fibers and glass fibers, and the corrugation angle is 45 DEG -60 DEG ; The plate spacing of the corrugated plate coalescence assembly is 10-15 mm, the surface is provided with a micro-groove array with a depth of 0.2-0.3 mm, and the direction of the micro-groove is at an angle of 30 DEG with the direction of the medium flow.

3. The method of claim 1, wherein the coal pyrolysis tar recovery method is characterized by, When the solid accumulation thickness on the surface of the metal sintering coated filter element reaches 3-5 mm, high-pressure nitrogen gas is introduced into the space above the filter tube plate, the space above the filter tube plate is pressurized, when the pressure reaches the set value, the downstream quick-opening backwashing and deslagging valve is opened, the solid particles on the surface of the metal sintering coated filter element are quickly separated from the metal sintering coated filter element under the action of pressure difference, the filter is discharged, the quick-opening backwashing and deslagging valve is closed, and the regeneration process of the metal sintering coated filter element is completed.

4. The method of claim 1, wherein the coal pyrolysis tar recovery method is characterized by, The de-solidified coal tar is continuously fed into the middle feeding port of the wash oil vacuum tower through a screw conveyor preheated to 210-230℃, and four-stage fractionation sections are arranged in the wash oil vacuum tower, from top to bottom, which are light wash oil trapping section, main fractionation section, heavy component buffer section and tower bottom heat circulation section; the light wash oil trapping section is operated at an absolute pressure of 15-25kPa, and is internally provided with three layers of inclined baffle trays, the tray surface is provided with a microporous distributor with a pore size of 0.8-1.2mm, and the top temperature of the light wash oil is controlled at 85-95℃ through an external condenser; the main fractionation section is filled with regularized stainless steel corrugated packing, the specific surface area of the packing is 450-500m² / m³, a distributed temperature sensor array is arranged in the main fractionation section, the axial temperature gradient is monitored in real time and the vacuum tower top pressure is feedback adjusted, so that the temperature gradient is maintained at 12-15℃ / m; the tower bottom heat circulation section is configured with a double-channel heat medium heating system, wherein the main channel adopts heat conducting oil circulation heating to maintain the tower bottom temperature at 195-205℃, and the auxiliary channel dynamically compensates temperature fluctuations through a steam ejector, and when the detected tower bottom viscosity exceeds 300mPa·s, the steam injection is automatically started to reduce the viscosity.

5. The method of claim 1, wherein the coal pyrolysis tar recovery method is characterized by, After the wash oil vapor is taken out from the top of the wash oil vacuum tower, it is first introduced into a primary condenser to exchange heat indirectly with 30-40℃ circulating cooling water, so that the temperature of the wash oil vapor is reduced to 80-90℃; Then, the wash oil vapor is introduced into a secondary condenser to exchange heat countercurrently with 5-10℃ chilled brine in the spiral pipe section, so that the wash oil vapor is further cooled to 40-50℃ and completely liquefied, and then transported to a wash oil storage tank; wherein the primary condenser adopts a corrugated plate fin structure, and the heat exchange surface is coated with a graphene-titanium dioxide composite anti-coking coating; the inner wall of the spiral pipe section of the secondary condenser is provided with a spiral micro-channel with a depth of 0.3-0.4mm and a channel spacing of 2-3mm.

6. A coal pyrolysis tar recovery system characterized by, It is used to realize the coal pyrolysis tar recovery method as claimed in any one of claims 1-5.

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