CN115873614A - Direct coal liquefaction system and direct coal liquefaction method - Google Patents
Direct coal liquefaction system and direct coal liquefaction method Download PDFInfo
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Abstract
The invention is suitable for the technical field of coal liquefaction, and provides a direct coal liquefaction system, which comprises: a coal pyrolysis unit; cracking gas alkali washing hydrogen production unit; a coal tar alkali washing phenol removal unit; a catalyst preparation unit; a coal tar hydrogenation unit. The invention also provides a direct coal liquefaction method, which comprises the following steps: coal pyrolysis; cracking gas alkali washing is carried out to prepare hydrogen; coal tar alkali washing to remove phenol; preparing a catalyst; coal tar hydrogenation: the method comprises the steps of taking hydrogen-rich gas as a hydrogen source and a semicoke catalyst as a catalyst carrier, carrying out two-stage hydrogenation reaction on dephenolized coal tar, and converting the hydrogenated coal tar into liquid fuel oil through a hydro-catalytic cracking lightening reaction. According to the invention, the product of coal pyrolysis is separated to obtain hydrogen-rich gas, coal tar and semicoke, so that the pyrolysis product is fully utilized, resources are saved, and the value of the product is maximized; and a solvent is not needed during hydrogenation, coal gasification is not needed for preparing hydrogen, and the hydrogenation process conditions are mild, so that the reaction energy consumption is reduced.
Description
Technical Field
The invention belongs to the technical field of coal liquefaction, and particularly relates to a direct coal liquefaction system and a direct coal liquefaction method.
Background
China is a country rich in coal, deficient in oil and low in gas, and the development of coal pyrolysis hydrogenation oil production has important significance for relieving the shortage of petroleum resources, balancing energy structure, reducing environmental pollution and ensuring national energy safety. Coal resources always occupy an important position in the energy structure of China, along with the implementation of carbon peaking, carbon neutralization strategic decisions and the increasing requirements on clean and environment-friendly in China, the clean and efficient utilization of the coal resources becomes an important requirement for changing the use mode of the coal resources, the products of coal pyrolysis are separated to obtain coal gas, coal tar and semicoke, the hydrogen-rich part is gathered into volatile products to obtain tar and coal gas, and the other part of carbon is gathered into nonvolatile solid residues to obtain the semicoke with high heat value.
Coal gas is a clean energy and can be used as an important raw material for synthesizing chemical engineering; the semicoke is a common carbon material with rich resources and low price, but has lower utilization level in China due to the reasons of underdeveloped pore structure, poor mechanical strength and the like compared with activated carbon; when coal tar is directly used as fuel, a large amount of NO is discharged during combustion due to high S and N contents in the coal tar x And SO x Contaminants, causing serious environmental pollution, such as: acid rain, haze and the like, the coal tar is subjected to deep processing treatment by adopting a hydro-upgrading process, so that resources can be reasonably utilized, the environmental pollution is reduced, and the use value of the coal tar is improved.
Application No. as201110120726.5 discloses a method for preparing oil by coal tar pitch hydrogenation and cracking secondary reaction lightening, which takes toluene as a solvent, a mixture of residual oil extracted from coal tar pitch and coal tar as a raw material, and the mass ratio of the toluene solvent to pitch tar is 1:1, adopting a two-stage fixed bed reactor, and reacting at the temperature of 380-450 ℃, the reaction pressure of 3.0-12.0 MPa and the reaction space velocity of 0.2-3 h -1 Under the condition of (1), the fuel oil is prepared by the combined action of the hydrogenation catalyst and the cracking catalyst secondary reaction catalyst, but the method needs to consume a large amount of toluene solvent, and can introduce aromatic hydrocarbon to cause the finally measured content of the aromatic hydrocarbon to be high, thereby influencing the analysis result.
The patent with the application number of 201310384969.9 discloses a direct coal liquefaction process mixed with medium-low temperature coal tar, which comprises the steps of purifying the medium-low temperature coal tar, distilling the purified medium-low temperature coal tar under reduced pressure or normal pressure, and cutting the medium-low temperature coal tar into heavy oil fractions and light oil fractions, wherein the operation pressure of a primary reactor and a secondary reactor is 15-20MPa, the hydrogen partial pressure is 10-15MPa, the reaction temperature is 420-480 ℃, the hydrogen-oil ratio of the secondary reactor is 600-1000, a catalyst is required to be added, the pyrolysis product semi-coke is not fully utilized, and the required reaction temperature is high, the pressure is high, the hydrogen consumption is large, and the energy consumption is also large.
The patent with the application number of 202111625648.4 discloses a system and a method for preparing mesophase pitch and oil products based on coal tar hydrogenation, wherein the coal tar is pretreated and then subjected to hydrogenation reaction in a slurry bed reactor under the action of nano molybdenum isooctanoate, and after the reaction, one part of liquid effluent is circulated, and the other part of liquid effluent is subjected to reduced pressure distillation to remove catalyst and impurities; the liquid products after the reaction are naphtha fraction, diesel oil fraction and mesophase pitch; all the diesel oil fractions are further refined and denitrified and desulfurized in a fixed bed reactor to produce special oil products, but the reaction temperature of the hydrogenation refining in the first refining reactor is 300-400 ℃, and the reaction pressure is 4-21 MPa; the constant temperature of the heavy component thermal polycondensation unit is 360-490 ℃, the reaction temperature is high, the pressure is high, and the energy consumption is high.
Therefore, the process for preparing the liquid fuel oil by hydrogenating the coal pyrolysis product, which has the advantages of low resource utilization, investment and operation cost maximization and mild operation conditions, has important significance.
Disclosure of Invention
An object of an embodiment of the present invention is to provide a direct coal liquefaction system, which aims to solve the problems in the background art.
The embodiment of the invention is realized in such a way that a direct coal liquefaction system comprises:
the coal pyrolysis unit is used for carrying out thermal decomposition reaction on the coal powder, separating thermal decomposition products to obtain semicoke and volatile matters, and returning part of the semicoke to the coal pyrolysis unit again;
the pyrolysis gas alkali washing hydrogen production unit is connected with the coal pyrolysis unit and used for separating the volatile matters to obtain coal tar and coal gas, performing alkali washing on the coal gas, and separating to obtain a hydrogen-rich gas;
the coal tar alkali washing dephenolization unit is connected with the pyrolysis gas alkali washing hydrogen production unit and is used for performing alkali washing on the coal tar and separating to obtain a water layer and dephenolized coal tar;
the catalyst preparation unit is connected with the coal pyrolysis unit and is used for loading active metal after the semicoke is activated to prepare a semicoke catalyst;
and the coal tar hydrogenation unit is respectively connected with the coal tar alkali washing dephenolization unit, the cracking gas alkali washing hydrogen preparation unit and the catalyst preparation unit and is used for carrying out two-stage hydrogenation on the dephenolized coal tar to prepare the liquid fuel oil.
Preferably, the coal pyrolysis unit comprises:
the pulverized coal is preheated in the first heat exchanger;
the first reactor is connected with the first heat exchanger, and the preheated coal powder is subjected to thermal decomposition reaction in the first reactor;
the first separator is connected with the first reactor and is used for separating thermal decomposition products generated by the first reactor to obtain semicoke and volatile matters;
and the second heat exchanger is connected between the first separator and the first reactor, and part of the semicoke is preheated by the second heat exchanger and then returns to the first reactor to be mixed with the pulverized coal for thermal decomposition reaction.
Preferably, the cracked gas alkali-washing hydrogen production unit comprises:
the third separator is connected with the first separator, and the volatile matters separated by the first separator enter the third separator to be separated to obtain coal tar and coal gas;
and the fourth separator is connected with the third separator, the coal gas and the alkali liquor are mixed and washed, and the hydrogen-rich gas is obtained through the fourth separator.
Preferably, the coal tar alkaline elution phenol unit comprises:
the coal tar is mixed with alkali liquor for washing, and is separated through the fifth separator to obtain a water layer and dephenolized coal tar;
and the fifth reactor is connected with the fifth separator, and the water layer is sent into the fifth reactor and is filled with carbon dioxide to obtain the phenolic compound.
Preferably, the catalyst preparation unit comprises:
the second separator is connected with the first separator, and the semicoke separated by the first separator is mixed with nitric acid, activated and treated and then filtered by the second separator;
and the fourth reactor is connected with the second separator, and the filtered semicoke is loaded with active metal through the fourth reactor to prepare the semicoke catalyst.
Preferably, the coal tar hydrogenation unit comprises:
the second reactor is respectively connected with the fourth separator, the fifth separator and the fourth reactor, the dephenolized coal tar obtained by the separation of the fifth separator is sent into the second reactor, hydrogen-rich gas obtained by the separation of the fourth separator and a semicoke catalyst obtained by the fourth reactor are introduced, and hydrogenation reaction is carried out in the second reactor;
and the third reactor is respectively connected with the fourth separator, the second reactor and the fourth reactor, and is used for carrying out deep catalytic hydrogenation reaction on the coal tar, and the coal tar after hydrogenation is converted into liquid fuel oil through a hydro-catalytic cracking lightening reaction.
Another object of an embodiment of the present invention is to provide a direct coal liquefaction method, including the steps of:
coal pyrolysis: separating coal powder after thermal decomposition reaction to obtain semicoke and volatile matters;
cracking gas alkali washing to prepare hydrogen: separating the volatile matter to obtain coal tar and coal gas, and performing alkali washing on the coal gas to obtain hydrogen-rich gas;
coal tar alkaline washing phenol removal: performing alkali washing on the coal tar to obtain dephenolized coal tar;
preparing a catalyst: activating the semicoke, and then loading active metal to prepare a semicoke catalyst;
coal tar hydrogenation: the method comprises the steps of taking hydrogen-rich gas as a hydrogen source and a semicoke catalyst as a catalyst carrier, carrying out two-stage hydrogenation reaction on dephenolized coal tar, and converting the hydrogenated coal tar into liquid fuel oil through a hydro-catalytic cracking lightening reaction.
Preferably, the method specifically comprises the following steps:
coal pyrolysis: preheating pulverized coal, performing thermal decomposition reaction, and separating to obtain semicoke and volatile matter, wherein part of semicoke is returned as solid heat carrier, and is mixed with pulverized coal for thermal decomposition reaction;
cracking gas alkali washing to prepare hydrogen: separating the volatile matter to obtain coal tar and coal gas, mixing and washing the coal gas and alkali liquor, and separating to obtain hydrogen-rich gas;
coal tar alkaline phenol removal: mixing coal tar with alkali liquor, washing, separating to obtain a water layer and dephenolized coal tar, introducing carbon dioxide into the water layer to reduce phenolic sodium salt, and discharging the obtained phenolic compound;
preparing a catalyst: mixing the semicoke and nitric acid, performing activation treatment at constant temperature, filtering to obtain semicoke, introducing water vapor, performing activation treatment at constant temperature, and loading active metal on the activated solid semicoke by a hydrothermal method to obtain a semicoke catalyst;
coal tar hydrogenation: heating dephenolized coal tar, introducing hydrogen-rich gas and a semicoke catalyst, carrying out primary hydrogenation reaction, heating the obtained product, introducing the hydrogen-rich gas and the semicoke catalyst, carrying out deep catalytic hydrogenation reaction on the coal tar, and converting the hydrogenated coal tar into liquid fuel oil through a hydro-catalytic cracking lightening reaction.
Preferably, the reaction temperature of the primary hydrogenation reaction is 310-350 ℃, and the pressure is 1-4 MPa.
Preferably, the reaction temperature of the deep catalytic hydrogenation reaction is 300-350 ℃, and the pressure is 6-9 MPa.
According to the direct coal liquefaction method provided by the embodiment of the invention, the pyrolysis product of coal is separated to obtain hydrogen-rich gas, coal tar and semicoke, the pyrolysis product is fully utilized, and the coal tar is hydrogenated to prepare liquid fuel oil, so that resources are saved and the value of the product is maximized; the hydrogen-rich part of the coal gas can be used for providing a hydrogen source in the coal tar hydrogenation process, and the other part of carbon is enriched in nonvolatile solid residues to obtain semicoke with rich pore structure, and the semicoke can be used as a carrier of a carbon-based catalyst; compared with the traditional coal liquefaction process, the embodiment of the invention does not need a solvent during hydrogenation, does not need coal gasification to prepare hydrogen, reduces the emission of carbon dioxide and the consumption of water, and simultaneously has mild hydrogenation process conditions, does not need high temperature and pressure, and reduces the reaction energy consumption.
Drawings
Fig. 1 is a structural diagram of a direct coal liquefaction system according to an embodiment of the present invention.
In the drawings: 1-a first heat exchanger; 2-a second heat exchanger; 3-a first reactor; 4-a second reactor; 5-a third reactor; 6-a fourth reactor; 7-a fifth reactor; 8-a first separator; 9-a second separator; 10-a third separator; 11-a fourth separator; 12-fifth separator.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.
As shown in fig. 1, a direct coal liquefaction system according to an embodiment of the present invention includes:
the first heat exchanger 1 is used for preheating pulverized coal in the first heat exchanger 1;
the first reactor 3 is connected with the first heat exchanger 1, and the preheated coal powder is subjected to thermal decomposition reaction in the first reactor 3;
the first separator 8 is connected with the first reactor 3 and is used for separating thermal decomposition products generated by the first reactor 3 to obtain semicoke and volatile matters;
the second heat exchanger 2 is connected between the first separator 8 and the first reactor 3, and part of the semicoke is preheated by the second heat exchanger 2, then sent into the spiral mixer, mixed with the pulverized coal, and then returned to the first reactor 3 for thermal decomposition reaction;
the third separator 10 is connected with the first separator 8, and the volatile matters separated by the first separator 8 enter the third separator 10 to be separated to obtain coal tar and coal gas;
the fourth separator 11 is connected with the third separator 10, the coal gas and the alkali liquor are mixed and washed, and hydrogen-rich gas is obtained through the fourth separator 11;
a fifth separator 12 connected with the third separator 10, wherein the coal tar is mixed and washed with alkali liquor, and is separated by the fifth separator 12 to obtain a water layer and dephenolized coal tar;
the fifth reactor 7 is connected with the fifth separator 12, and the water layer is sent into the fifth reactor 7 and is filled with carbon dioxide to obtain a phenolic compound;
the second separator 9 is connected with the first separator 8, and the semicoke separated by the first separator 8 is mixed with nitric acid, activated and treated, and then filtered by the second separator 9;
the fourth reactor 6 is connected with the second separator 9, and the filtered semicoke is loaded with active metal through the fourth reactor 6 to prepare a semicoke catalyst;
the second reactor 4 is respectively connected with the fourth separator 11, the fifth separator 12 and the fourth reactor 6, dephenolized coal tar obtained by separating the fifth separator 12 is sent into the second reactor 4, hydrogen-rich gas obtained by separating the fourth separator 11 and a semicoke catalyst obtained by the fourth reactor 6 are introduced, and hydrogenation reaction is carried out in the second reactor 4;
and the third reactor 5 is respectively connected with the fourth separator 11, the second reactor 4 and the fourth reactor 6, and is used for carrying out deep catalytic hydrogenation reaction on the coal tar, and the coal tar after hydrogenation is converted into liquid fuel oil through a hydro-catalytic cracking lightening reaction.
The screened coal powder is introduced into a first heat exchanger 1 for preheating, and then is mixed with circulating hot semicoke from a first separator 8 in a spiral mixer, then the mixture enters a first reactor 3 for thermal decomposition reaction, a part of the semicoke generated from the first reactor 3 is cooled to obtain a solid product, the rest of the semicoke is sent back to the first reactor 3 by hot air to be used as a heat source to provide heat for the first reactor 3, volatile matters separated by the first separator 8 are sent to a third separator 10 to obtain a tar product and coal gas, the tar product is dephenolized, the coal gas is washed with alkali and dried, the coal gas and the semicoke loaded with active metals are sent to a second reactor 4 together for hydrogenation reaction for desulfurization, denitrification and deoxidation, the obtained product is heated to enter a third reactor 5 for deep hydrogenation, and the coal tar is converted into liquid fuel oil.
Another embodiment of the present invention provides a direct coal liquefaction method, including the steps of:
(1) Coal pyrolysis:
after raw coal is crushed and screened, pulverized coal with the particle size of less than 5mm enters a first heat exchanger 1 to be preheated to 85-90 ℃ primarily, is mixed with 850 ℃ circulating hot semicoke from a first separator 8 in a spiral mixer, the ratio of the coal to the semicoke is about 1.4-1.8, then enters a first reactor 3 to be subjected to thermal decomposition reaction, the operating temperature of the first reactor 3 is 600-800 ℃, the semicoke and volatile matters are obtained by separation of the first separator 8, the semicoke discharged from the first separator 8 is divided into two ways, one part is cooled to obtain solid semicoke, activation and catalyst preparation steps are carried out, the rest is solid heat carrier, and the solid semicoke and the pulverized coal are returned to the first reactor 3 together, and the circulation is carried out, and the semicoke yield is different under the Ar atmosphere at 500-800 ℃;
(2) Cracking gas alkali washing to prepare hydrogen:
the volatile matter obtained by the separation of the first separator 8 enters a third separator 10 to obtain coal tar and coal gas through separation, the coal gas is mixed and washed with 10-15% of sodium hydroxide solution, hydrogen-rich gas is obtained through a fourth separator 11, and the hydrogen-rich gas is sent to a coal tar hydrogenation step to serve as raw material gas;
(3) Coal tar alkaline phenol removal:
mixing coal tar and 10-15% sodium hydroxide solution, washing, separating an oil layer from a water layer through a fifth separator 12, sending the water layer into a fifth reactor 7, introducing carbon dioxide to reduce phenolic sodium salt to obtain a phenolic compound, and sending the oil layer into a second reactor 4 for hydrogenation reaction;
(4) Nitric acid/water activated carbocoal:
the semicoke product obtained in the first separator 8 is mixed with 55% nitric acid, the volume ratio of the nitric acid solution to the semicoke is 1.2, the semicoke is activated for 2 hours at the constant temperature of 85 ℃, and then the semicoke is pumped into a second separator 9, filtered, washed with water to pH value>6, drying in vacuum at 120 ℃ for 12h, introducing steam into the semicoke activated by nitric acid at the flow rate of 1000 mL/min -1 Activating for 4h at the constant temperature of 700 ℃;
(5) Preparing a catalyst:
loading the activated solid semicoke with MoS doped with W/Ni/Co by a hydrothermal method 2 Preparing a catalyst, and feeding the obtained semi-coke carrier catalyst into a second reactor 4;
(6) Coal tar slurry bed hydrogenation:
carrying out two-stage hydrogenation on the dephenolized coal tar pretreated in the step (3), heating the dephenolized coal tar by a heating furnace, feeding the heated dephenolized coal tar from the bottom of a second reactor 4 (the second reactor 4 can be a slurry bed reactor), introducing hydrogen-rich gas subjected to alkali washing in the step (2) and the semicoke catalyst treated in the step (5), controlling the reaction temperature to be 310-350 ℃ and the pressure to be 1.0-4.0 MPa, and carrying out hydrogenation reaction in the second reactor 4 to saturate olefins, demetallize, desulfurize, denitrify and deoxidize; heating the obtained product, putting the product into a third reactor 5 (the third reactor 5 can be a fixed bed reactor), introducing the hydrogen-rich gas after alkali washing in the step (2) and the semicoke catalyst treated in the step (5) to perform deep catalytic hydrogenation reaction on the coal tar, controlling the temperature to be 300-350 ℃ and the pressure to be 6.0-9.0 MPa, and converting the hydrogenated coal tar into liquid fuel oil through a hydrocatalytic cracking lightening reaction;
specifically, in the step (1), the operating temperature of the first reactor 3 may be 750 ℃;
in the step (5), the hydrothermal method load modification condition is 600 ℃, and the retention time is 4h;
in the step (6), the average particle size of the catalyst is 100nm, and the injection amount of the catalyst is 80 to 500ppm; the hydrogen-oil ratio in the third reactor 5 is 1500-2000, and the total liquid volume space velocity is 0.8-0.9 h -1 。
In the method adopted by the embodiment of the invention, a slurry bed reactor is adopted for hydrogenation, the raw material adaptability is strong, particularly some heavy and solid-content inferior oil products are strong, the adopted carbon-based semi-coke catalyst has high activity, is easy to obtain and has low reaction temperature, sulfur, nitrogen, oxygen and metal ions can be deeply removed according to the requirement of liquid fuel oil, and the saturation of aromatic hydrocarbon can be adjusted;
compared with the traditional coal liquefaction process, the process method provided by the embodiment of the invention does not need a solvent during hydrogenation, the hydrogenation process condition is mild, and excessive temperature and pressure are not needed, so that resources are saved; in the processes of denitrification, deoxidation and desulfurization of oil product refining, the second-stage hydrogenation reaction adopts semicoke nickel-based catalyst instead of common Al 2 O 3 The investment cost is reduced, and the gas circulation which is rich in hydrogen and is obtained by pyrolysis reaction products is used as the hydrogen supply part of the reactor, so that the long-period stable operation of the device is ensured.
Specific implementations of the present invention are described in detail below with reference to specific embodiments.
Example 1
A method of direct coal liquefaction comprising the steps of:
(1) After lignite is crushed and screened, coal powder with the granularity of less than 5mm enters a first heat exchanger 1, is preliminarily preheated to 90 ℃, is mixed with 850 ℃ circulating hot semicoke from a first separator 8 in a spiral mixer, the ratio of coal to semicoke is about 1.4, is pyrolyzed in Ar atmosphere, then enters a first reactor 3 for thermal decomposition reaction, the operating temperature of the reactor is 600 ℃, semicoke generated in the reactor is discharged in two ways, one part of semicoke is cooled to obtain solid products, the rest of semicoke enters the bottom of a semicoke heater, and is lifted by hot air at 440 ℃ and returned to the first reactor 3, the circulation is carried out, and the yield of the pyrolysis semicoke can reach 61% in Ar atmosphere at the temperature;
(2) Volatile matters generated by pyrolysis in the first reactor 3 are led out of the furnace through a first separator 8, dedusted by a cyclone separator, fed into a tar recovery cooling system, recovered to obtain a tar product, gas enters a next gas treatment device, pyrolysis gas and 10% sodium hydroxide solution are mixed and washed through a mixer, then introduced into a dryer to be dried to remove water, and fed into a two-stage hydrogenation liquefaction unit of coal tar to serve as raw material gas, wherein the yield of the coal tar is about 10.43%, the yield of the gas is about 15%, and the yield of semicoke is about 40%;
(3) Mixing and washing coal tar and 10% sodium hydroxide solution through a mixer, separating an oil layer from a water layer by a steam-blowing method, introducing carbon dioxide into the water layer to reduce sodium phenolate, passing through a fifth reactor 7 to obtain a phenolic compound, wherein the yield can reach 2%, and pumping the oil layer into a second reactor 4;
(4) Heating the oil layer treated in the step (3) by a heater, then introducing the oil layer into a dehydration tank for layered dehydration, dehydrating chloride ions along with water, introducing the dehydrated coal tar into a flash tower for further flash evaporation to remove trace water, and finishing pretreatment of the coal tar;
(5) Preparing the semicoke obtained by the first separator 8 into powder with the granularity of 100 meshes, mixing the powder with nitric acid with the concentration of 55%, enabling the volume ratio of a nitric acid solution to the semicoke to be 1.2, heating the mixed solution by a heater, refluxing at the constant temperature of 85 ℃, activating for 2h, introducing into a second separator 9, filtering out the semicoke, washing with water until the pH value is reached>6, drying in vacuum at 120 ℃ for 12h, introducing steam into the semicoke activated by nitric acid at the flow rate of 1000 mL/min -1 Activating for 4 hours at the constant temperature of 700 ℃;
(6) Using the obtained solid semicoke as a carrier to load MoS 2 Adding sodium molybdate, thiourea and tungsten into distilled water, vigorously stirring for 1 hr to form a homogeneous solution, and feeding into a fourth reactor 6 (high) with W as active componentA pressure reactor) is adopted, the reaction is carried out for 6 hours at the temperature of 340 ℃, the product is naturally cooled and collected, hydrochloric acid, distilled water and absolute ethyl alcohol are used for washing the product, impurities are removed, and finally the product is dried for a plurality of hours, wherein the loading capacity of the active components is 100 percent of the mass of the catalyst;
(7) Carrying out two-stage hydrogenation on the dephenolized coal tar pretreated in the step (4), heating the dephenolized coal tar by a heating furnace, feeding the heated dephenolized coal tar from the bottom of a slurry bed reactor (a second reactor 4), introducing the hydrogen-rich gas subjected to alkali washing in the step (2) and the semicoke catalyst treated in the step (6), controlling the reaction temperature to be 310 ℃ and the pressure to be 4MPa, and carrying out hydrogenation reaction in the slurry bed reactor to saturate olefins, demetallize, desulfurize, denitrify and deoxidize; heating the obtained product to enter a fixed bed reactor (a third reactor 5) to enable the coal tar to generate a deep catalytic hydrogenation reaction, controlling the temperature to be 300 ℃ and the pressure to be 9MPa, converting the hydrogenated coal tar into liquid fuel oil through a hydro-catalytic cracking lightening reaction, and enabling the oil yield of the fuel oil to be more than 76% in terms of the asphalt raw material.
Example 2
(1) After crushing and screening bituminous coal, feeding pulverized coal with the particle size of less than 5mm into a dryer, preliminarily preheating the pulverized coal to 85 ℃, mixing the pulverized coal with 850 ℃ circulating hot semicoke from a first separator 8 in a spiral mixer, wherein the ratio of the coal to the semicoke is about 1.5, then feeding the pulverized coal into a first reactor 3 for thermal decomposition reaction, wherein the operating temperature of the reactor is 600 ℃, discharging the semicoke generated in the reactor in two ways, cooling one part of the semicoke to obtain a solid product, feeding the rest of the semicoke to the bottom of a semicoke heater, and pumping the rest of the semicoke back to the first reactor 3 as a heat source by hot air at 450 ℃, circulating the way, and under the temperature, the yield of the pyrolytic semicoke under Ar atmosphere can reach 60%;
(2) Volatile matters generated by pyrolysis in the first reactor 3 are led out of the furnace through a first separator 8, dedusted by a cyclone separator, fed into a tar recovery cooling system, recovered to obtain a tar product, gas is fed into a next gas treatment device, pyrolysis gas and a sodium hydroxide solution with the content of 12% are mixed and washed through a mixer, then the mixture is fed into a dryer to evaporate water, and the mixture is fed into a coal tar hydrogenation liquefaction unit to serve as a raw material gas, so that the yield of the obtained coal tar is about 9%, and the yield of the gas is about 10%;
(3) Mixing and washing coal tar and a sodium hydroxide solution with the content of 12% through a mixer, separating an oil layer from a water layer by a steam-blowing method, introducing carbon dioxide into the water layer to reduce a phenolic sodium salt to obtain a phenolic compound, and pumping the oil layer into a second reactor 4;
(4) Heating the oil layer treated in the step (3) by a heater, then feeding the oil layer into a dehydration tank for layered dehydration, dehydrating chloride ions along with water, feeding the dehydrated coal tar into a flash tower for further flash evaporation to remove trace water, and finishing pretreatment of the coal tar;
(5) Preparing the semicoke obtained by the first separator 8 into powder with the granularity of 150 meshes, passing the powder through a mixer, and mixing the powder with nitric acid with the concentration of 55%, wherein the volume ratio of a nitric acid solution to the semicoke is 1.2; heating the mixed solution by a heater, refluxing at constant temperature of 85 ℃, activating for 2h, introducing into a second separator 9, filtering to remove semicoke, and washing with water to pH>6, drying in vacuum at 120 ℃ for 12h, introducing steam into the semicoke activated by nitric acid at the flow rate of 1000 mL/min -1 Activating for 4 hours at the constant temperature of 700 ℃;
(6) Using solid semicoke as a carrier to load MoS 2 Adding sodium molybdate, thiourea and nickel into distilled water, violently stirring for 1h to form a uniform solution, then sending the uniform solution into a high-pressure reactor 6, reacting for 6h at 360 ℃, naturally cooling and collecting a product, washing the product with hydrochloric acid, distilled water and absolute ethyl alcohol to remove impurities, and finally drying for a plurality of hours, wherein the loading capacity of the active component is 100% of the mass of the catalyst;
(7) And (3) performing two-stage hydrogenation on the dephenolized coal tar pretreated in the step (4), heating the dephenolized coal tar by a heating furnace, feeding the heated dephenolized coal tar into a slurry bed reactor, introducing the hydrogen-rich gas subjected to alkali washing in the step (2), introducing the semicoke catalyst treated in the step (6), controlling the reaction temperature to be 330 ℃ and the pressure to be 3MPa, performing hydrogenation reaction in the slurry bed reactor to saturate olefins, demetallize, desulfurize, denitrify and deoxidize, heating the obtained product to enter a fixed bed reactor, performing deep catalytic hydrogenation reaction on the coal tar, controlling the temperature to be 350 ℃ and the pressure to be 6MPa, converting the hydrogenated coal tar into liquid fuel oil through a catalytic hydrocracking lightening reaction, and calculating the oil yield of the fuel oil by using naphtha products to be more than 77%.
Example 3
(1) After lignite is crushed and screened, coal powder with the granularity of less than 5mm enters a dryer to be preheated to 90 ℃ primarily, is mixed with 850 ℃ circulating hot semicoke from a first separator 8 in a spiral mixer, the ratio of coal to semicoke is about 1.8, is pyrolyzed in Ar atmosphere, then enters a first reactor 3 to be subjected to pyrolysis reaction, the operating temperature of the reactor is 750 ℃, the semicoke generated from the reactor is discharged in two ways, one part of the semicoke is cooled to obtain solid products, the rest of the semicoke enters the bottom of a semicoke heater, and is conveyed back to the first reactor 3 by hot air at 450 ℃, the circulation is carried out, and the yield of the pyrolysis semicoke can reach 57% in Ar atmosphere at the temperature;
(2) Volatile matters generated by pyrolysis in the first reactor 3 are led out of the furnace through a first separator 8, dedusted by a cyclone separator, fed into a tar recovery cooling system, recovered to obtain a tar product, gas is fed into a next gas treatment device, pyrolysis gas and 15% sodium hydroxide solution are mixed and washed through a mixer, then the mixture is fed into a dryer to evaporate water, and the mixture is fed into a two-stage hydrogenation liquefaction unit of coal tar to be used as raw material gas, so that the yield of the obtained coal tar is about 6.5%, and the yield of the gas is about 9.8%;
(3) Mixing and washing coal tar and 15% sodium hydroxide solution through a mixer, separating an oil layer from a water layer by a steam-blowing method, introducing carbon dioxide into the water layer to reduce sodium phenolate to obtain a phenolic compound, wherein the yield can reach 2%, and pumping the oil layer;
(4) Heating the oil layer treated in the step (3) by a heater, then feeding the oil layer into a dehydration tank for layered dehydration, dehydrating chloride ions along with water, feeding the dehydrated coal tar into a flash tower for further flash evaporation to remove trace water, and finishing pretreatment of the coal tar;
(5) Preparing the semicoke obtained by the first separator 8 into powder with the granularity of 200 meshes, mixing the powder with nitric acid with the concentration of 55%, enabling the volume ratio of a nitric acid solution to the semicoke to be 1.2, heating the mixed solution by a heater, refluxing at the constant temperature of 85 ℃, activating for 2h, introducing into a second separator 9, filtering out the semicoke, and washing with water until the pH value is reached>6, vacuum drying at 120 deg.C for 12h, activating with nitric acidIntroducing steam into the semicoke at the flow rate of 1000 mL/min -1 Activating for 4 hours at the constant temperature of 700 ℃;
(6) Using solid semicoke as a carrier to load MoS 2 Adding Co as an active component, adding sodium molybdate, thiourea and cobalt into distilled water, violently stirring for 1h to form a uniform solution, then sending the uniform solution into a high-pressure reactor, reacting for 6h at 380 ℃, naturally cooling and collecting a product, washing the product with hydrochloric acid, distilled water and absolute ethyl alcohol to remove impurities, and finally drying for a plurality of hours, wherein the loading capacity of the active component is 100% of the mass of the catalyst;
(7) And (3) carrying out two-stage hydrogenation on the dephenolized coal tar pretreated in the step (4), heating the dephenolized coal tar in a heating furnace, feeding the heated dephenolized coal tar from the bottom of a stirring reactor, introducing the hydrogen-rich gas subjected to alkali washing in the step (2), controlling the reaction temperature to be 350 ℃ and the pressure to be 2MPa, carrying out hydrogenation reaction in a slurry bed reactor to saturate olefin, demetallizing, desulfurizing, denitrifying and deoxidizing, heating the obtained product, feeding the product into the reactor, carrying out deep catalytic hydrogenation reaction on the coal tar in the reactor, controlling the temperature to be 350 ℃ and the pressure to be 6MPa, converting the hydrogenated coal tar into liquid fuel oil through a hydro-catalytic cracking lightening reaction, and enabling the oil yield of the fuel oil to be more than 65% in terms of asphalt raw materials.
The above description is intended to be illustrative of the preferred embodiment of the present invention and should not be taken as limiting the invention, but rather, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.
Claims (10)
1. A direct coal liquefaction system, comprising:
the coal pyrolysis unit is used for carrying out thermal decomposition reaction on the coal powder, separating thermal decomposition products to obtain semicoke and volatile matters, and returning part of the semicoke to the coal pyrolysis unit again;
the pyrolysis gas alkali washing hydrogen production unit is connected with the coal pyrolysis unit and used for separating the volatile matters to obtain coal tar and coal gas, performing alkali washing on the coal gas, and separating to obtain a hydrogen-rich gas;
the coal tar alkali washing dephenolization unit is connected with the pyrolysis gas alkali washing hydrogen production unit and is used for performing alkali washing on the coal tar and separating to obtain a water layer and dephenolized coal tar;
the catalyst preparation unit is connected with the coal pyrolysis unit and is used for loading active metal after the semicoke is activated to prepare a semicoke catalyst;
and the coal tar hydrogenation unit is respectively connected with the coal tar alkali washing dephenolization unit, the cracking gas alkali washing hydrogen preparation unit and the catalyst preparation unit and is used for carrying out two-stage hydrogenation on the dephenolized coal tar to prepare the liquid fuel oil.
2. The direct coal liquefaction system of claim 1, wherein the coal pyrolysis unit comprises:
the coal dust preheating device comprises a first heat exchanger (1), wherein coal dust is preheated in the first heat exchanger (1);
the first reactor (3) is connected with the first heat exchanger (1), and the preheated coal powder is subjected to thermal decomposition reaction in the first reactor (3);
the first separator (8) is connected with the first reactor (3) and is used for separating thermal decomposition products generated by the first reactor (3) to obtain semicoke and volatile matters;
and the second heat exchanger (2) is connected between the first separator (8) and the first reactor (3), and part of the semicoke is preheated by the second heat exchanger (2) and then returns to the first reactor (3) to be mixed with the pulverized coal for thermal decomposition reaction.
3. The direct coal liquefaction system of claim 2, wherein the cracked gas alkali hydrogen production unit comprises:
the third separator (10) is connected with the first separator (8), and the volatile matters separated by the first separator (8) enter the third separator (10) to be separated to obtain coal tar and coal gas;
and the fourth separator (11) is connected with the third separator (10), the coal gas and the alkali liquor are mixed and washed, and the hydrogen-rich gas is obtained through the fourth separator (11).
4. The coal direct liquefaction system of claim 3, wherein the coal tar base elution phenol unit comprises:
the fifth separator (12) is connected with the third separator (10), the coal tar is mixed and washed with alkali liquor, and the mixture is separated by the fifth separator (12) to obtain a water layer and dephenolized coal tar;
and the fifth reactor (7) is connected with the fifth separator (12), and the water layer is conveyed into the fifth reactor (7) and is filled with carbon dioxide to obtain the phenolic compound.
5. The direct coal liquefaction system of claim 4, wherein the catalyst preparation unit comprises:
the second separator (9) is connected with the first separator (8), and the semicoke separated by the first separator (8) is mixed with nitric acid for activation treatment and then filtered by the second separator (9);
and the fourth reactor (6) is connected with the second separator (9), and the filtered semicoke is loaded with active metal through the fourth reactor (6) to prepare the semicoke catalyst.
6. The direct coal liquefaction system of claim 5, wherein the coal tar hydrogenation unit comprises:
the second reactor (4) is respectively connected with the fourth separator (11), the fifth separator (12) and the fourth reactor (6), dephenolized coal tar obtained by separating the fifth separator (12) is sent into the second reactor (4), hydrogen-rich gas obtained by separating the fourth separator (11) and a semicoke catalyst obtained by the fourth reactor (6) are introduced, and hydrogenation reaction is carried out in the second reactor (4);
and the third reactor (5) is respectively connected with the fourth separator (11), the second reactor (4) and the fourth reactor (6) to carry out deep catalytic hydrogenation reaction on the coal tar, and the hydrogenated coal tar is converted into liquid fuel oil through a hydrocatalytic cracking lightening reaction.
7. A direct coal liquefaction process, comprising the steps of:
coal pyrolysis: separating pulverized coal after thermal decomposition reaction to obtain semicoke and volatile matters;
cracking gas alkali washing to prepare hydrogen: separating the volatile matter to obtain coal tar and coal gas, and performing alkali washing on the coal gas to obtain hydrogen-rich gas;
coal tar alkaline washing phenol removal: performing alkali washing on the coal tar to obtain dephenolized coal tar;
preparing a catalyst: activating the semicoke, and then loading active metal to prepare a semicoke catalyst;
coal tar hydrogenation: the method comprises the steps of taking hydrogen-rich gas as a hydrogen source and a semicoke catalyst as a catalyst carrier, carrying out two-stage hydrogenation reaction on dephenolized coal tar, and converting the hydrogenated coal tar into liquid fuel oil through a hydro-catalytic cracking lightening reaction.
8. The direct coal liquefaction method according to claim 7, comprising the steps of:
coal pyrolysis: preheating coal powder, performing thermal decomposition reaction, separating to obtain semicoke and volatile matter, returning part of semicoke as solid heat carrier, mixing with coal powder, and performing thermal decomposition reaction;
cracking gas alkali washing to prepare hydrogen: separating the volatile matter to obtain coal tar and coal gas, mixing the coal gas with alkali liquor, washing, and separating to obtain hydrogen-rich gas;
coal tar alkaline washing phenol removal: mixing coal tar with alkali liquor, washing, separating to obtain a water layer and dephenolized coal tar, introducing carbon dioxide into the water layer to reduce phenolic sodium salt, and discharging the obtained phenolic compound;
preparing a catalyst: mixing the semicoke and nitric acid, performing activation treatment at constant temperature, filtering to obtain semicoke, introducing water vapor, performing activation treatment at constant temperature, and loading active metal on the activated solid semicoke by a hydrothermal method to obtain a semicoke catalyst;
coal tar hydrogenation: heating dephenolized coal tar, introducing hydrogen-rich gas and a semicoke catalyst, carrying out primary hydrogenation reaction, heating the obtained product, introducing the hydrogen-rich gas and the semicoke catalyst, carrying out deep catalytic hydrogenation reaction on the coal tar, and converting the hydrogenated coal tar into liquid fuel oil through a hydro-catalytic cracking lightening reaction.
9. The direct coal liquefaction method according to claim 8, wherein the reaction temperature of the primary hydrogenation reaction is 310 to 350 ℃ and the pressure is 1 to 4MPa.
10. The direct coal liquefaction method according to claim 8, wherein the deep catalytic hydrogenation reaction is performed at a temperature of 300 to 350 ℃ and a pressure of 6 to 9MPa.
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