A method for the pretreatment of coal tar feedstocks

Abstract

The present disclosure relates to a method for pretreating coal tar raw material, which comprises: S1, mixing the coal tar raw material with a solvent and then performing centrifugal separation to obtain a first solid phase material and a first liquid phase material; S2, filtering the first liquid phase material to obtain a second liquid phase material and a third liquid phase material, the solid content of the second liquid phase material being higher than that of the third liquid phase material; S3, mixing the second liquid phase material with the solvent and then returning to step S1 to perform the centrifugal separation; and S4, under a hydrogen condition, contacting the third liquid phase material with a pretreatment agent to perform a pretreatment reaction, and performing gas-liquid separation on the obtained pretreatment reaction product; wherein the solvent is an organic compound solvent or solvent oil. The method of the present disclosure can effectively reduce the metal and ash content in the pretreated coal tar.

Description

Technical Field

[0001] This disclosure relates to the field of coal tar processing, and more specifically, to a method for low-pressure pretreatment of coal tar feedstock. Background Technology

[0002] With the sustained and rapid development of my country's social economy, the demand for petroleum products is also increasing. However, petroleum is a non-renewable energy source and is facing a crisis of depletion. In contrast, China has relatively abundant coal reserves; therefore, the production of liquid fuels from coal has become a fundamental direction for coal processing and utilization.

[0003] With the rapid development of modern coal chemical industry, the output of coal tar is increasing, making its clean processing and effective utilization increasingly important. Currently, the main utilization pathways for coal tar are deep processing to extract chemical products or hydrogenation to produce clean fuels. In recent years, the number of fixed-bed coal tar hydrogenation units in China has been increasing. Among them, fixed-bed hydrogenation units have the advantages of simple process, low investment, simple operation, and high technological maturity. However, when processing coal tar feedstocks with high metal, ash, and asphaltenes content, they are prone to bed blockage, rapid pressure drop, heat exchanger coking and blockage, and rapid catalyst deactivation due to asphaltenes depositing on the catalyst. This forces the unit to shut down, shortens the operating time, and seriously affects the economic benefits of enterprises.

[0004] Therefore, in order to extend the operating cycle of coal tar hydrogenation units, it is necessary to pre-treat the coal tar feedstock to remove metals and ash and to achieve the hydrogenation conversion of asphaltene, before it is hydrogenated in a fixed bed to produce clean fuels, which can greatly extend the operating cycle of the unit.

[0005] Currently, the pretreatment of coal tar in China mainly adopts methods such as centrifugal separation, sedimentation separation, solvent extraction, electric field purification and filtration separation. These methods have disadvantages such as poor pretreatment effect, low efficiency and low utilization rate of coal tar resources.

[0006] CN106701157A discloses a method for demetallizing high-temperature coal tar. Although the method uses solvent oil for dilution, adds alcohols, and uses a demetallization reactor to pretreat the high-temperature coal tar to remove metals, water is introduced during the process. The treated water is phenolic water, which contains high levels of phenols, ammonia nitrogen, etc., making it difficult to treat and not meeting environmental protection requirements.

[0007] CN105713658B discloses a pretreatment process for low-temperature coal tar, in which the coal tar raw material is pretreated through steps such as sedimentation separation, primary electrostatic desalination, and secondary electrostatic desalination. However, the process is complex, the operating cost is high, and water is introduced during the implementation process, which also presents the problem of difficult treatment of phenolic water.

[0008] CN101012385A discloses a pretreatment method for coal tar, which uses distillate oil and aromatics to perform two-stage extraction on coal tar to remove ash and asphaltenes. Although solvent extraction separation method has a good purification effect, it requires a large amount of solvent, has a complex process, and has high operating costs. Summary of the Invention

[0009] The purpose of this disclosure is to provide a method for pretreatment of coal tar feedstock. This method is simple, easy to operate, and has low investment costs, and can effectively reduce the metal and ash content in pretreated coal tar.

[0010] To achieve the above objectives, this disclosure provides a method for pretreating coal tar feedstock. The method includes: S1, mixing the coal tar feedstock with a solvent and then centrifuging to obtain a first solid phase material and a first liquid phase material; S2, filtering the first liquid phase material to obtain a second liquid phase material and a third liquid phase material, wherein the solid content of the second liquid phase material is higher than that of the third liquid phase material; S3, mixing the second liquid phase material with the solvent and then returning to step S1 for centrifugation; S4, under hydrogen-containing conditions, contacting the third liquid phase material with a pretreatment agent to carry out a pretreatment reaction, and performing gas-liquid separation on the obtained pretreatment reaction product; wherein the solvent is an organic compound solvent or solvent oil.

[0011] Optionally, in step S1, the volume ratio of the solvent to the coal tar raw material is (0.001-0.5):1, preferably (0.005-0.3):1;

[0012] In step S3, the volume ratio of the solvent to the second liquid phase material is (0.01-1.0):1, preferably (0.05-0.5):1.

[0013] Optionally, in step S2, the filtration conditions include: a temperature of 80-250℃ and a pressure of 0.1-1.0MPa; preferably, the temperature is 100-230℃ and the pressure is 0.3-0.6MPa.

[0014] Based on the total weight of the first liquid phase material, the amount of the second liquid phase material is 3-30% by weight, preferably 5-20% by weight.

[0015] Optionally, in step S4, after the third liquid phase material is brought into contact with the first pretreatment agent to carry out a first reaction, the obtained first reaction product is brought into contact with the second pretreatment agent to carry out a second reaction, thereby obtaining the pretreatment reaction product.

[0016] The active components in the first pretreatment agent and the second pretreatment agent are each independently a Group VIB metal and / or a Group VIII metal.

[0017] Optionally, in step S4, the conditions for the first reaction include: a hydrogen partial pressure of 0.5-3.5 MPa, a reaction temperature of 120-300 °C, and a hydrogen-to-oil volume ratio of 10-500 Nm. 3 / m 3 The volume hourly space velocity (VHSV) of the feed liquid is 0.2-2 h⁻¹. -1 ;

[0018] Preferably, the hydrogen partial pressure is 1-3 MPa, the reaction temperature is 180-280°C, and the hydrogen-to-oil volume ratio is 30-300 Nm. 3 / m 3 The volume hourly space velocity (HSV) of the feed liquid is 0.3-1.5 h⁻¹. -1 ;

[0019] The conditions for the second reaction include: a hydrogen partial pressure of 0.5-3.0 MPa, a reaction temperature of 160-340℃, and a hydrogen-to-oil volume ratio of 10-500 Nm. 3 / m 3 The volumetric hourly space velocity (VHSV) of the feed liquid is 0.15-1.5 h⁻¹. -1 ;

[0020] Preferably, the hydrogen partial pressure is 1-3 MPa, the reaction temperature is 200-320°C, and the hydrogen-to-oil volume ratio is 30-300 Nm. 3 / m 3 The volume hourly space velocity (HSV) of the feed liquid is 0.2-1 h⁻¹. -1 .

[0021] Optionally, the first pretreatment agent includes pretreatment agent I, pretreatment agent II, pretreatment agent III and pretreatment agent IV arranged sequentially from upstream to downstream; the second pretreatment agent includes pretreatment agent IV, pretreatment agent V and pretreatment agent VI arranged sequentially from upstream to downstream.

[0022] The pretreatment agent I has an average diameter of 15-17 mm, and the carrier is silicon oxide or aluminum oxide;

[0023] The pretreatment agent II has an average diameter of 9-11 mm and, based on the total weight of the pretreatment agent II, contains 0.05-0.2% by weight of nickel oxide, 0.5-1.0% by weight of molybdenum oxide, and the balance being silicon oxide or aluminum oxide.

[0024] The pretreatment agent III has an average diameter of 5.6-6.5 mm and, based on the total weight of the pretreatment agent III, contains 0.1-0.5% by weight of nickel oxide, 0.5-2.5% by weight of molybdenum oxide, and the balance being silicon oxide or aluminum oxide.

[0025] The pretreatment agent IV has an average diameter of 2.5-3.5 mm and, based on the total weight of the pretreatment agent IV, contains 0.1-1% by weight of nickel oxide, 1-5.5% by weight of molybdenum oxide, and the balance of silicon oxide or aluminum oxide.

[0026] The pretreatment agent V has an average diameter of 2.5-3.5 mm and, based on the total weight of the pretreatment agent V, contains 0.5-1.5% by weight of nickel oxide, 1.5-6.5% by weight of molybdenum oxide, and the balance of silicon oxide or aluminum oxide.

[0027] The pretreatment agent VI has an average diameter of 1-1.2 mm and contains 1-3% by weight of nickel oxide, 5-8% by weight of molybdenum oxide, and the balance of silicon oxide or aluminum oxide, based on the total weight of the pretreatment agent VI.

[0028] Optionally, in the first reaction, relative to 100 volumes of pretreatment agent IV used in the second reaction, the amount of pretreatment agent I is 10-40 volumes, the amount of pretreatment agent II is 10-40 volumes, the amount of pretreatment agent III is 20-60 volumes, and the amount of pretreatment agent IV is 20-60 volumes.

[0029] In the second reaction, the amount of pretreatment agent V is 40-80 volumes, and the amount of pretreatment agent VI is 40-80 volumes.

[0030] Optionally, the organic compound solvent includes one or more of C5-C9 hydrocarbons, C1-C4 alcohols, inorganic acids, organic acids, organic amines, and quaternary ammonium salts;

[0031] Preferably, the organic compound solvent includes one or more of n-pentane, n-hexane, n-heptane, benzene, toluene, xylene, methanol, ethanol, formic acid, acetic acid, oxalic acid, phosphoric acid, citric acid, tartaric acid, pyruvic acid, ethanolamine, quaternary ammonium salts, and polyethylene glycol.

[0032] The solvent oil includes one or more of naphtha, kerosene, diesel oil, tail oil, light oil, phenol oil, wash oil, naphthalene oil, and anthracene oil.

[0033] Optionally, in step S1, a centrifugal separation device is used for the centrifugal separation, and the centrifugal separation device is selected from a horizontal screw centrifuge and / or a disc centrifuge; the conditions for centrifugal separation include: an operating temperature of 50-120℃ and a rotation speed of 3000-8000 rpm.

[0034] Optionally, in step S2, a filtration device is used for filtration, wherein the filter element of the filtration device is selected from one of stainless steel sintered wire mesh, stainless steel sintered powder, ceramic membrane and flexible filter cloth.

[0035] Optionally, the coal tar raw material includes one or more of low-temperature coal tar, medium-low-temperature coal tar, medium-temperature coal tar, and high-temperature coal tar, or is a mixture of one or more of low-temperature coal tar, medium-low-temperature coal tar, medium-temperature coal tar, and high-temperature coal tar with anthracene oil and / or wash oil.

[0036] The method disclosed herein has the following advantages through the above technical solution:

[0037] (1) Effectively reduce the metal and ash content in pretreated coal tar;

[0038] (2) It has the advantages of low equipment investment, simple process flow, simple operation and low operating cost;

[0039] (3) No water is introduced, thus avoiding environmental pollution problems caused by the difficulty in treating phenolic water and meeting environmental protection requirements.

[0040] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0041] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0042] Figure 1 This is a flowchart illustrating the method for pretreatment of coal tar feedstock provided in this disclosure.

[0043] Explanation of reference numerals in the attached figures

[0044] 1. Coal tar raw material 2. Solvent 3. Mixing tank

[0045] 4. First solid-liquid separator; 5. First solid phase material; 6. Second solid-liquid separator

[0046] 7. Hydrogen-containing gas; 8. First pretreatment tank; 9. Second pretreatment tank

[0047] 10. Gas-liquid separator; 11. Gas; 12. Pre-treated product tank Detailed Implementation

[0048] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0049] This disclosure provides a method for pretreatment of coal tar feedstock, the method comprising: S1, mixing the coal tar feedstock with a solvent and then centrifuging to obtain a first solid phase material and a first liquid phase material; S2, filtering the first liquid phase material to obtain a second liquid phase material and a third liquid phase material, wherein the solid content of the second liquid phase material is higher than that of the third liquid phase material; S3, mixing the second liquid phase material with the solvent and then returning to step S1 for centrifugation; S4, under hydrogen-containing conditions, contacting the third liquid phase material with a pretreatment agent to carry out a pretreatment reaction, and performing gas-liquid separation on the obtained pretreatment reaction product; wherein the solvent is an organic compound solvent or a solvent oil.

[0050] The method disclosed herein employs a process combining centrifugation and filtration, and uses organic compound solvents or solvent oils to assist in the separation during both the centrifugation and filtration steps, which can effectively reduce the metal and ash content in pretreated coal tar.

[0051] In one specific embodiment of this disclosure, the content of organic impurities in the third liquid phase material is not greater than 0.015% by weight, preferably not greater than 0.01% by weight, and the content of organic impurities in the second liquid phase material is not less than 1% by weight, preferably not less than 1.5% by weight.

[0052] In one specific embodiment of this disclosure, in step S1, the volume ratio of the solvent to the coal tar raw material is (0.001-0.5):1, preferably (0.005-0.3):1. According to this disclosure, the temperature at which the coal tar raw material and the solvent are mixed in step S1 is not specifically limited; for example, it can be 30-100°C.

[0053] In one specific embodiment of this disclosure, in step S2, the filtration conditions include: a temperature of 80-250°C and a pressure of 0.1-1.0 MPa, preferably, the temperature is 100-230°C and the pressure is 0.3-0.6 MPa; based on the total weight of the first liquid phase material, the amount of the second liquid phase material is 3-30% by weight, preferably 5-20% by weight.

[0054] In one specific embodiment of this disclosure, in step S3, the volume ratio of the solvent to the second liquid phase material is (0.01-1.0):1, preferably (0.05-0.5):1. According to this disclosure, the temperature at which the second liquid phase material and the solvent are mixed in step S3 is not specifically limited; for example, it can be 50-75°C.

[0055] In one specific embodiment of this disclosure, in step S4, after the third liquid phase material is contacted with the first pretreatment agent to carry out a first reaction, the obtained first reaction product is contacted with the second pretreatment agent to carry out a second reaction to obtain the pretreatment reaction product; the active components in the first pretreatment agent and the second pretreatment agent are each independently a Group VIB metal and / or a Group VIII metal.

[0056] In a preferred embodiment of this disclosure, in step S4, the conditions for the first reaction include: a hydrogen partial pressure of 0.5-3.5 MPa, a reaction temperature of 120-300°C, and a hydrogen-to-oil volume ratio of 10-500 Nm. 3 / m 3 The volume hourly space velocity (VHSV) of the feed liquid is 0.2-2 h⁻¹. -1 Preferably, the hydrogen partial pressure is 1-3 MPa, the reaction temperature is 180-280℃, and the hydrogen-to-oil volume ratio is 30-300 Nm. 3 / m 3 The volume hourly space velocity (HSV) of the feed liquid is 0.3-1.5 h⁻¹. -1 ;

[0057] The conditions for the second reaction include: a hydrogen partial pressure of 0.5-3.0 MPa, a reaction temperature of 160-340℃, and a hydrogen-to-oil volume ratio of 10-500 Nm. 3 / m 3 The volumetric hourly space velocity (VHSV) of the feed liquid is 0.15-1.5 h⁻¹. -1 Preferably, the hydrogen partial pressure is 1-3 MPa, the reaction temperature is 200-320℃, and the hydrogen-to-oil volume ratio is 30-300 Nm. 3 / m 3 The volume hourly space velocity (HSV) of the feed liquid is 0.2-1 h⁻¹. -1 .

[0058] In one specific embodiment of this disclosure, the first pretreatment agent includes pretreatment agent I, pretreatment agent II, pretreatment agent III and pretreatment agent IV arranged sequentially from upstream to downstream; the second pretreatment agent includes pretreatment agent IV, pretreatment agent V and pretreatment agent VI arranged sequentially from upstream to downstream.

[0059] The pretreatment agent I has an average diameter of 15-17 mm, and the carrier is silicon oxide or aluminum oxide; the pretreatment agent II has an average diameter of 9-11 mm, and based on the total weight of the pretreatment agent II, it contains 0.05-0.2 wt% nickel oxide, 0.5-1.0 wt% molybdenum oxide, and the balance being silicon oxide or aluminum oxide; the pretreatment agent III has an average diameter of 5.6-6.5 mm, and based on the total weight of the pretreatment agent III, it contains 0.1-0.5 wt% nickel oxide, 0.5-2.5 wt% molybdenum oxide, and the balance being silicon oxide or aluminum oxide; the pretreatment agent IV has an average diameter of 2.5-3 mm. The pretreatment agent IV has an average diameter of 5 mm and contains 0.1-1% by weight of nickel oxide, 1-5.5% by weight of molybdenum oxide, and the balance of silicon oxide or aluminum oxide, based on the total weight of the pretreatment agent IV; the pretreatment agent V has an average diameter of 1-1.2 mm and contains 0.5-1.5% by weight of nickel oxide, 1.5-6.5% by weight of molybdenum oxide, and the balance of silicon oxide or aluminum oxide, based on the total weight of the pretreatment agent V; the pretreatment agent VI has an average diameter of 1-1.2 mm and contains 1-3% by weight of nickel oxide, 5-8% by weight of molybdenum oxide, and the balance of silicon oxide or aluminum oxide, based on the total weight of the pretreatment agent VI.

[0060] In one specific embodiment of this disclosure, in the first reaction, relative to 100 volumes of pretreatment agent IV used in the second reaction, the amount of pretreatment agent I is 10-40 volumes, the amount of pretreatment agent II is 10-40 volumes, the amount of pretreatment agent III is 20-60 volumes, and the amount of pretreatment agent IV is 20-60 volumes.

[0061] In the second reaction, the amount of pretreatment agent V is 40-80 volumes, and the amount of pretreatment agent VI is 40-80 volumes.

[0062] In one specific embodiment of this disclosure, the organic compound solvent includes one or more of C5-C9 hydrocarbons, C1-C4 alcohols, inorganic acids, organic acids, organic amines, and quaternary ammonium salts; preferably, the organic compound solvent includes one or more of n-pentane, n-hexane, n-heptane, benzene, toluene, xylene, methanol, ethanol, formic acid, acetic acid, oxalic acid, phosphoric acid, citric acid, tartaric acid, pyruvic acid, ethanolamine, quaternary ammonium salts, and polyethylene glycol.

[0063] In one specific embodiment of this disclosure, the solvent oil may be one or more of the following: hydrogenated product oil, cut distillate oil from coal tar feedstock, and the solvent oil itself. The hydrogenated product oil may be obtained by hydrogenating one or more of the following: petroleum-based feedstock, coal tar feedstock, and Fischer-Tropsch synthetic oil. For example, it may include one or more of naphtha, kerosene, diesel oil, and tail oil. The cut distillate oil from the coal tar feedstock may include one or more of the following: light oil, phenolic oil, wash oil, naphthalene oil, and anthracene oil.

[0064] In one specific embodiment of this disclosure, in step S1, a centrifugal separation device is used to perform the centrifugal separation, the centrifugal separation device being selected from a horizontal screw centrifuge and / or a disc centrifuge; the conditions for the centrifugal separation may include: an operating temperature of 50-120℃ and a rotation speed of 3000-8000 rpm.

[0065] In one specific embodiment of this disclosure, in step S2, a filtration device is used for filtration. The filtration device can be any device capable of filtration, and the filter element of the filtration device can be selected from stainless steel sintered wire mesh, stainless steel sintered powder, ceramic membrane, and flexible filter cloth.

[0066] According to this disclosure, coal tar, as is well known to those skilled in the art, refers to coal tar produced by coal pyrolysis, coal gasification, or other processes. The coal tar raw materials may include low-temperature coal tar produced during coal gasification, or one or more of the following: low-temperature coal tar, medium-temperature coal tar, medium-temperature coal tar, and high-temperature coal tar produced during coal pyrolysis or coking processes (including low-temperature pyrolysis, medium-temperature pyrolysis, and high-temperature coking processes); or a mixture of one or more of the following: low-temperature coal tar, medium-temperature coal tar, medium-temperature coal tar, and high-temperature coal tar with anthracene oil and / or wash oil.

[0067] According to this disclosure, the distillation range of the low-temperature coal tar can be 50-450℃; the distillation range of the medium-low temperature coal tar can be 50-550℃; the distillation range of the medium temperature coal tar can be 50-600℃; and the distillation range of the high-temperature coal tar can be 50-650℃.

[0068] like Figure 1 As shown, in a preferred embodiment of this disclosure, a method comprising the following steps is used for low-pressure pretreatment of coal tar feedstock:

[0069] S1. The coal tar raw material 1 to be pretreated and the solvent 2 are introduced into the mixing tank 3 for mixing, and then introduced into the first solid-liquid separator 4 for centrifugal separation of solid residue and liquid to obtain the first solid phase material 5 and the first liquid phase material.

[0070] S2. The first liquid phase material is introduced into the second solid-liquid separator 6 for filtration to obtain a second liquid phase material and a third liquid phase material, wherein the solid content of the second liquid phase material is higher than that of the third liquid phase material.

[0071] S3. After mixing the second liquid phase material with solvent 2, return it to the first solid-liquid separator 5 in step S1 for further centrifugal separation of solid residue and liquid stream.

[0072] S4. The third liquid phase material is mixed with hydrogen-containing gas 7 and then sequentially enters the first pretreatment tank 8 and the second pretreatment tank 9 to contact the pretreatment agent for pretreatment reaction. The pretreatment reaction product is introduced into the gas-liquid separator 10 for gas-liquid separation. The separated gas 11 is used as fuel gas, and the separated liquid stream is the pretreated product, which then enters the pretreated product tank 12. The pretreated product is used as the raw material for the subsequent fixed-bed hydrogenation unit.

[0073] In one specific embodiment of this disclosure, the first pretreatment tank and the second pretreatment tank can each be independently selected from either an upflow operation mode or a downflow operation mode.

[0074] In one specific embodiment of this disclosure, there may be two or more first pretreatment tanks and second pretreatment tanks, and the first pretreatment tank and the second pretreatment tank are connected in series.

[0075] In one specific embodiment of this disclosure, when the pressure drop of the first pretreatment tank reaches 0.5-0.7 MPa, the first pretreatment tank can be disconnected from the system, and the reaction stream can be transferred from the first pretreatment tank to the second pretreatment tank. At this time, the disconnected first pretreatment tank is cleaned, and the pretreatment agent is replaced. After the pretreatment agent in the first pretreatment tank is replaced, the reaction stream is transferred back to the first pretreatment tank and connected in series with the second pretreatment tank. When the pressure drop of the second pretreatment tank reaches 0.5-0.7 MPa, the stream from the first pretreatment tank is transferred to a gas-liquid separator, and the second pretreatment tank is disconnected from the system for cleaning and pretreatment agent replacement. After the pretreatment agent in the second pretreatment tank is replaced, the stream from the first pretreatment tank is transferred back to the second pretreatment tank.

[0076] The present disclosure will be further illustrated by the following examples, but the present disclosure is not limited thereto.

[0077] In the following examples, all raw materials used were commercially available unless otherwise specified. The properties of the coal tar raw materials to be pretreated are shown in Table 1.

[0078] In Examples 1-6, along the direction of the reaction stream, the pretreatment agents in the first pretreatment tank are pretreatment agent I, pretreatment agent II, pretreatment agent III and pretreatment agent IV, respectively; and the pretreatment agents in the second pretreatment tank are pretreatment agent IV, pretreatment agent V and pretreatment agent VI, respectively.

[0079] Among them, pretreatment agent I is a porous cylindrical pretreatment agent with a carrier of silicon oxide or aluminum oxide and a diameter of 15-17 mm; pretreatment agent II is a honeycomb cylindrical pretreatment agent with a diameter of 9-11 mm, and its composition is 0.15 wt% nickel oxide, 0.8 wt% molybdenum oxide, and the balance being silicon oxide or aluminum oxide; pretreatment agent III is a Raschig ring-shaped pretreatment agent with a diameter of 5.6-6.5 mm, and its composition is 0.3 wt% nickel oxide, 1.5 wt% molybdenum oxide, and the balance being silicon oxide or aluminum oxide; pretreatment agent IV... The first pretreatment agent is a Raschig ring with a diameter of 2.5-3.5 mm, composed of 0.5 wt% nickel oxide, 2.5 wt% molybdenum oxide, and the balance being silicon oxide or aluminum oxide; the second pretreatment agent is a clover-shaped clover with a diameter of 1-1.2 mm, composed of 1.0 wt% nickel oxide, 3.5 wt% molybdenum oxide, and the balance being silicon oxide or aluminum oxide; the third pretreatment agent is a butterfly-shaped clover with a diameter of 1.0-1.2 mm, composed of 2.0 wt% nickel oxide, 6.0 wt% molybdenum oxide, and the balance being silicon oxide or aluminum oxide.

[0080] In the following embodiments, unless otherwise specified, based on pretreatment agent IV in the second pretreatment tank, the filling volume of pretreatment agent I in the first pretreatment tank is 20 vol%, the filling volume of pretreatment agent II is 20 vol%, the filling volume of pretreatment agent III is 35 vol%, and the filling volume of pretreatment agent IV is 35 vol%. The filling volume of pretreatment agent V in the second pretreatment tank is 60 vol%, and the filling volume of pretreatment agent VI is 60 vol%.

[0081] Example 1

[0082] S1. Using coal tar to be pretreated as raw material, and mixing n-heptane with it in a mixing tank at a volume ratio of 0.15:1, the mixture enters the first solid-liquid separator for centrifugal separation of solid residue and liquid to obtain the first solid phase material and the first liquid phase material.

[0083] S2. The first liquid phase material is introduced into the second solid-liquid separator and filtered at 160℃ and 0.35MPa to obtain the second liquid phase material and the third liquid phase material. The solid content of the second liquid phase material is higher than that of the third liquid phase material. Based on the total weight of the first liquid phase material, the amount of the second liquid phase material is 12% by weight.

[0084] S3. The second liquid phase material separated by the second solid-liquid separator is mixed with n-heptane and then introduced into the first solid-liquid separator for further solid-liquid centrifugal separation, wherein the volume ratio of n-heptane to the second liquid phase material is 0.3:1.

[0085] S4. The third liquid phase material separated by the second solid-liquid separator is mixed with hydrogen-containing gas and then enters the first pretreatment tank and the second pretreatment tank in sequence to contact the pretreatment agent for pretreatment reaction. The material coming out of the pretreatment tank enters the gas-liquid separator for gas-liquid separation. The separated gas is used as fuel gas, and the separated liquid material is the pretreated product, which then enters the pretreated product tank. The pretreated product is suitable as a raw material for the subsequent coal tar hydrogenation unit.

[0086] The specific operating conditions of the pretreatment tank are shown in Table 2, and the properties of the pretreated coal tar are shown in Table 3.

[0087] Example 2

[0088] S1. Using coal tar to be pretreated as raw material, and mixing xylene with it in a mixing tank at a volume ratio of 0.05:1, the mixture enters the first solid-liquid separator for centrifugal separation of solid residue and liquid to obtain the first solid phase material and the first liquid phase material.

[0089] S2. The first liquid phase material is introduced into the second solid-liquid separator and filtered at 100℃ and 0.4MPa to obtain the second liquid phase material and the third liquid phase material. The solid content of the second liquid phase material is higher than that of the third liquid phase material. Based on the total weight of the first liquid phase material, the amount of the second liquid phase material is 10% by weight.

[0090] S3. The second liquid phase material separated by the second solid-liquid separator is mixed with xylene and then introduced into the first solid-liquid separator for further solid-liquid centrifugal separation, wherein the volume ratio of xylene to the second liquid phase material is 0.1:1.

[0091] S4. The third liquid phase material separated by the second solid-liquid separator is mixed with hydrogen-containing gas and then enters the first pretreatment tank and the second pretreatment tank in sequence to contact the pretreatment agent for pretreatment reaction. The material coming out of the pretreatment tank enters the gas-liquid separator for gas-liquid separation. The separated gas is used as fuel gas, and the separated liquid material is the pretreated product, which then enters the pretreated product tank. The pretreated product is suitable as a raw material for the subsequent coal tar hydrogenation unit.

[0092] The specific operating conditions of the pretreatment tank are shown in Table 2, and the properties of the pretreated coal tar are shown in Table 3.

[0093] Example 3

[0094] S1. Using coal tar to be pretreated as raw material, and mixing it with ethanol at a volume ratio of 0.3:1 in a mixing tank, the mixture enters the first solid-liquid separator for centrifugal separation of solid residue and liquid to obtain the first solid phase material and the first liquid phase material.

[0095] S2. The first liquid phase material is introduced into the second solid-liquid separator and filtered at 230℃ and 0.45MPa to obtain the second liquid phase material and the third liquid phase material. The solid content of the second liquid phase material is higher than that of the third liquid phase material. Based on the total weight of the first liquid phase material, the amount of the second liquid phase material is 15% by weight.

[0096] S3. The second liquid phase material separated by the second solid-liquid separator is mixed with ethanol and then introduced into the first solid-liquid separator for further solid-liquid centrifugal separation, wherein the volume ratio of ethanol to the second liquid phase material is 0.5:1.

[0097] S4. The third liquid phase material separated by the second solid-liquid separator is mixed with hydrogen-containing gas and then enters the first pretreatment tank and the second pretreatment tank in sequence to contact the pretreatment agent for pretreatment reaction. The material coming out of the pretreatment tank enters the gas-liquid separator for gas-liquid separation. The separated gas is used as fuel gas, and the separated liquid material is the pretreated product, which then enters the pretreated product tank. The pretreated product is suitable as a raw material for the subsequent coal tar hydrogenation unit.

[0098] The specific operating conditions of the pretreatment tank are shown in Table 2, and the properties of the pretreated coal tar are shown in Table 3.

[0099] Example 4

[0100] The coal tar feedstock was pretreated using the same method as in Example 1, except that the solvent used in steps S1 and S3 was hydrogenated tail oil.

[0101] Example 5

[0102] The coal tar feedstock was pretreated using the same method as in Example 1, except that in step S1, the volume ratio of n-heptane to the coal tar to be pretreated was 0.5:1.

[0103] Example 6

[0104] The coal tar feedstock was pretreated using the same method as in Example 1, except that in step S2, the filtration temperature was 90°C and 0.2 MPa, and the amount of the second liquid phase material obtained was 25% by weight, based on the total weight of the first liquid phase material.

[0105] Example 7

[0106] The coal tar feedstock was pretreated using the same method as in Example 1, except that in step S3, the volume ratio of n-heptane to the second liquid phase material was 0.04:1.

[0107] Example 8

[0108] The coal tar raw material was pretreated using the same method as in Example 1. The only difference was that in step S4, the third liquid phase material separated by the second solid-liquid separator was mixed with hydrogen-containing gas and then entered the first pretreatment tank to contact the pretreatment agent in the first pretreatment tank for pretreatment reaction.

[0109] Comparative Example 1

[0110] The coal tar feedstock was pretreated using the same method as in Example 1, except that n-heptane was not used in steps S1 and S3, while the other operating conditions were the same as in Example 1.

[0111] The specific operating conditions of the pretreatment tank are shown in Table 2, and the properties of the pretreated coal tar are shown in Table 3.

[0112] Table 1

[0113]

[0114]

[0115] Table 2

[0116]

[0117]

[0118] Table 3

[0119]

[0120] As can be seen from the above, the method disclosed herein can effectively reduce the metal and ash content in pretreated coal tar.

[0121] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0122] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0123] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method for pretreatment of coal tar feedstock, wherein, The method includes: S1. The coal tar raw material is mixed with a solvent and then centrifuged to obtain a first solid phase material and a first liquid phase material; the volume ratio of the solvent to the coal tar raw material is (0.005-0.3):

1. S2. The first liquid phase material is filtered to obtain a second liquid phase material and a third liquid phase material, wherein the solid content of the second liquid phase material is higher than that of the third liquid phase material; the filtration conditions include: temperature of 100-230℃ and pressure of 0.3-0.6MPa; the filtration is performed using a filtration device, wherein the filter element of the filtration device is selected from one of stainless steel sintered wire mesh, stainless steel sintered powder, ceramic membrane and flexible filter cloth; S3. After mixing the second liquid phase material with the solvent, return to step S1 for centrifugal separation; the volume ratio of the solvent to the second liquid phase material is (0.05-0.5):1; S4. Under hydrogen-containing conditions, the third liquid phase material is brought into contact with the pretreatment agent to carry out a pretreatment reaction, and the resulting pretreatment reaction product is subjected to gas-liquid separation. Wherein, the solvent is an organic compound solvent; the organic compound solvent includes one or more of n-pentane, n-hexane, n-heptane, benzene, toluene, xylene, methanol, ethanol, formic acid, acetic acid, oxalic acid, citric acid, tartaric acid, pyruvic acid, ethanolamine and polyethylene glycol.

2. The method according to claim 1, wherein, In step S2, the amount of the second liquid phase material is 3-30% by weight, based on the total weight of the first liquid phase material.

3. The method according to claim 2, wherein, In step S2, based on the total weight of the first liquid phase material, the amount of the second liquid phase material is 5-20% by weight.

4. The method according to claim 1, wherein, In step S4, after the third liquid phase material is brought into contact with the first pretreatment agent to carry out a first reaction, the obtained first reaction product is brought into contact with the second pretreatment agent to carry out a second reaction, thereby obtaining the pretreatment reaction product. The active components in the first pretreatment agent and the second pretreatment agent are each independently a Group VIB metal and / or a Group VIII metal.

5. The method according to claim 4, wherein, In step S4, the conditions for the first reaction include: a hydrogen partial pressure of 0.5-3.5 MPa, a reaction temperature of 120-300 °C, and a hydrogen-to-oil volume ratio of 10-500 Nm. 3 / m 3 The volume hourly space velocity (VHSV) of the feed liquid is 0.2-2 h⁻¹. -1 ; The conditions for the second reaction include: a hydrogen partial pressure of 0.5-3.0 MPa, a reaction temperature of 160-340℃, and a hydrogen-to-oil volume ratio of 10-500 Nm. 3 / m 3 The volumetric hourly space velocity (VHSV) of the feed liquid is 0.15-1.5 h⁻¹. -1 .

6. The method according to claim 5, wherein, In step S4, the conditions for the first reaction include: a hydrogen partial pressure of 1-3 MPa, a reaction temperature of 180-280°C, and a hydrogen-to-oil volume ratio of 30-300 Nm. 3 / m 3 The volume hourly space velocity (HSV) of the feed liquid is 0.3-1.5 h⁻¹. -1 ; The conditions for the second reaction include: a hydrogen partial pressure of 1-3 MPa, a reaction temperature of 200-320°C, and a hydrogen-to-oil volume ratio of 30-300 Nm. 3 / m 3 The volume hourly space velocity (HSV) of the feed liquid is 0.2-1 h⁻¹. -1 .

7. The method according to claim 5, wherein, The first pretreatment agent includes pretreatment agent I, pretreatment agent II, pretreatment agent III and pretreatment agent IV arranged sequentially from upstream to downstream; the second pretreatment agent includes pretreatment agent IV, pretreatment agent V and pretreatment agent VI arranged sequentially from upstream to downstream; The pretreatment agent I has an average diameter of 15-17 mm, and the carrier is silicon oxide or aluminum oxide; The pretreatment agent II has an average diameter of 9-11 mm and, based on the total weight of the pretreatment agent II, contains 0.05-0.2% by weight of nickel oxide, 0.5-1.0% by weight of molybdenum oxide, and the balance of silicon oxide or aluminum oxide. The average diameter of the pretreatment agent III is 5.6-6.5 mm, and based on the total weight of the pretreatment agent III, it contains 0.1-0.5% by weight of nickel oxide, 0.5-2.5% by weight of molybdenum oxide, and the balance of silicon oxide or aluminum oxide. The pretreatment agent IV has an average diameter of 2.5-3.5 mm and, based on the total weight of the pretreatment agent IV, contains 0.1-1% by weight of nickel oxide, 1-5.5% by weight of molybdenum oxide, and the balance of silicon oxide or aluminum oxide. The pretreatment agent V has an average diameter of 2.5-3.5 mm and, based on the total weight of the pretreatment agent V, contains 0.5-1.5% by weight of nickel oxide, 1.5-6.5% by weight of molybdenum oxide, and the balance of silicon oxide or aluminum oxide. The pretreatment agent VI has an average diameter of 1-1.2 mm and, based on the total weight of the pretreatment agent VI, contains 1-3% by weight of nickel oxide, 5-8% by weight of molybdenum oxide, and the balance of silicon oxide or aluminum oxide.

8. The method according to claim 7, wherein, In the first reaction, relative to 100 volumes of pretreatment agent IV used in the second reaction, the amount of pretreatment agent I is 10-40 volumes, the amount of pretreatment agent II is 10-40 volumes, the amount of pretreatment agent III is 20-60 volumes, and the amount of pretreatment agent IV is 20-60 volumes. In the second reaction, the amount of pretreatment agent V is 40-80 volumes, and the amount of pretreatment agent VI is 40-80 volumes.

9. The method according to claim 1, wherein, In step S1, a centrifugal separation device is used to perform the centrifugal separation, and the centrifugal separation device is selected from a horizontal screw centrifuge and / or a disc centrifuge; The conditions for centrifugal separation include: an operating temperature of 50-120℃ and a rotation speed of 3000-8000 rpm.

10. The method according to claim 1, wherein, The coal tar raw material includes one or more of low-temperature coal tar, medium-temperature coal tar, and high-temperature coal tar, or a mixture of one or more of low-temperature coal tar, medium-temperature coal tar, and high-temperature coal tar with anthracene oil and / or wash oil.

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