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CN-118853217-B - Coal tar processing method

CN118853217BCN 118853217 BCN118853217 BCN 118853217BCN-118853217-B

Abstract

The invention discloses a coal tar processing method which comprises the following steps of (1) mixing coal tar raw materials, alkali metal and hydrogen, then entering an alkali metal treatment reaction zone for reaction, (2) separating the reacted materials obtained in the step (1), and (3) separating the oil phase materials obtained in the step (2) into a hydrocracking reaction zone, wherein reaction effluent is separated to obtain gas, gasoline, diesel oil and tail oil fractions. The method organically combines alkali metal treatment and hydrocracking processes, and has excellent impurity removal effect, so that the quality of gasoline and diesel products is effectively improved, and the running period of the device is prolonged.

Inventors

  • ZHANG WENFANG
  • YIN DONGDONG
  • MENG ZHAOHUI
  • LIU LING
  • YANG XIUQI

Assignees

  • 中国石油化工股份有限公司
  • 中石化（大连）石油化工研究院有限公司

Dates

Publication Date
20260505
Application Date
20230426

Claims (16)

  1. 1. A method for processing coal tar, the method comprising the steps of: (1) Mixing coal tar raw materials, alkali metal and hydrogen, and then entering an alkali metal treatment reaction zone for reaction; (2) Separating the reacted material obtained in the step (1); (3) The oil phase material obtained by separation treatment in the step (2) enters a hydrocracking reaction zone, and the reaction effluent is separated to obtain gas, gasoline, diesel oil and tail oil fraction; in the step (1), the alkali metal treatment reaction zone at least comprises two alkali metal treatment reactors, wherein coal tar raw materials, alkali metal and hydrogen are mixed and then enter a first alkali metal treatment reactor for primary reaction; In the step (1), the content of alkali metal alkoxy compound in the material after one-time reaction is controlled to be 0.5 to 15.0 weight percent, and the solid content is controlled to be 0.10 to 0.50 weight percent; in the step (1), the alkali metal is one or more of lithium, sodium and potassium; An auxiliary agent is also introduced in the step (1), wherein the auxiliary agent is alkali metal hydrosulfide, the alkali metal hydrosulfide comprises at least one of lithium hydrosulfide, sodium hydrosulfide and potassium hydrosulfide, and the mass ratio of the alkali metal to the auxiliary agent is 1 (0.1-0.8); In the step (1), the mass ratio of alkali metal to coal tar raw material in the first alkali metal treatment reactor is (2.0-10.0) 100, and the mass ratio of alkali metal introduced in the first alkali metal treatment reactor to the second alkali metal treatment reactor is (10-60) 100; In the step (1), the operation condition of the first alkali metal treatment reactor is that the reaction temperature is 200-350 ℃, the hydrogen partial pressure is 0.5-15.0MPa, the reaction time is 0.1-5.0h, and the hydrogen-oil volume ratio is 100-1000Nm 3 /m 3 ; In the step (1), compared with the first alkali metal treatment reactor, the reaction temperature of the second alkali metal treatment reactor is 10-50 ℃, the hydrogen partial pressure is 1.0-5.0MPa, the reaction time is 0.2-1.0h, and the hydrogen oil volume ratio is 100-500Nm 3 /m 3 .
  2. 2. The method according to claim 1, wherein in the step (1), the coal tar raw material is pretreated and then enters an alkali metal treatment reaction zone, the water content of the pretreated coal tar raw material is 0.5-3.0 wt%, the solid content of the pretreated coal tar raw material is 0.05-0.35 wt%, the oxygen content of the pretreated coal tar raw material is 2.0-20.0wt% and the phenolic compound content of the pretreated coal tar raw material is 10.0-35.0wt%.
  3. 3. The method according to claim 2, wherein in the step (1), the coal tar raw material is pretreated and then enters an alkali metal treatment reaction zone, the water content of the pretreated coal tar raw material is 1.0-2.5 wt%, the solid content of the pretreated coal tar raw material is 0.10-0.20 wt%, the oxygen content of the pretreated coal tar raw material is 5.0-10.0 wt%, and the phenolic compound content of the pretreated coal tar raw material is 15.0-25.0 wt%.
  4. 4. The method according to claim 1, wherein in the step (1), the alkali metal is sodium.
  5. 5. The method according to claim 1, wherein in the step (1), the mass ratio of the alkali metal to the coal tar raw material is (8.0-15.0): 100.
  6. 6. The method according to claim 1, wherein in the step (1), the alkali metal hydrosulfide is sodium hydrosulfide, and the mass ratio of the alkali metal to the auxiliary agent is 1 (0.2-0.5).
  7. 7. The method according to claim 1, wherein in the step (1), the auxiliary agent is mixed with a solvent, the mixture is mixed with coal tar raw material and hydrogen and then enters an alkali metal treatment reaction zone for reaction, the solvent is at least one of dimethyl sulfoxide, N-dimethylformamide, diethyl ether and benzene, the mass ratio of the auxiliary agent to the solvent is 1 (2-20), the mixing temperature is 100-400 ℃, and the mixing time is 0.2-2.0h.
  8. 8. The method according to claim 7, wherein in the step (1), the solvent is benzene, the mass ratio of the auxiliary agent to the solvent is 1 (5-10), the mixing temperature is 200-300 ℃, and the mixing time is 0.3-1.0h.
  9. 9. The method according to claim 1, wherein in the step (1), the alkali metal alkoxide is contained in an amount of 1.0 to 5.0wt% and the solid is contained in an amount of 0.20 to 0.35wt% in the material after the one-time reaction.
  10. 10. The method according to claim 1, wherein in the step (1), the mass ratio of the alkali metal to the coal tar raw material in the first alkali metal treatment reactor is (3.0-5.0) 100, and the mass ratio of the alkali metal introduced in the first alkali metal treatment reactor to the second alkali metal treatment reactor is (20-50) 100.
  11. 11. The method according to claim 1, wherein in the step (1), the first alkali metal treatment reactor is operated at a reaction temperature of 280-350 ℃, a hydrogen partial pressure of 2.0-10.0MPa, a reaction time of 0.5-2.0h and a hydrogen oil volume ratio of 350-750Nm 3 /m 3 .
  12. 12. The method according to claim 1, wherein in the step (1), the reaction temperature of the second alkali metal treatment reactor is 10-30 ℃ higher than that of the first alkali metal treatment reactor, the hydrogen partial pressure is 1.0-3.0MPa, the reaction time is 0.2-0.5h longer, and the hydrogen oil volume ratio is 200-350Nm 3 /m 3 .
  13. 13. The method according to claim 1, wherein in the step (2), the separation treatment is performed by using one or more of a vacuum filter, a pressure filter, a filter centrifuge, a decanter centrifuge and a membrane filter.
  14. 14. The method according to claim 1, wherein in the step (3), at least one hydrocracking catalyst is filled in the hydrocracking reaction zone, the hydrocracking catalyst comprises a carrier and an active metal component, the active metal component is one or more of molybdenum, tungsten, cobalt and nickel, and the content of the active metal component is 5-40wt.% in terms of metal oxide based on the weight of the catalyst.
  15. 15. The process according to claim 1, wherein in the step (3), the hydrocracking reaction zone is operated at a reaction temperature of 330 to 450 ℃, a reaction pressure of 8.0 to 20.0MPa, a space velocity of 0.1 to 1.0h -1 and a hydrogen-oil volume ratio of 100 to 2500Nm 3 /m 3 .
  16. 16. The method according to claim 15, wherein in the step (3), the hydrocracking reaction zone is operated at a reaction temperature of 350 ℃ to 430 ℃, a reaction pressure of 10.0 to 18.0MPa, a space velocity of 0.2 to 0.6h -1 and a hydrogen-oil volume ratio of 500 to 1500Nm 3 /m 3 .

Description

Coal tar processing method Technical Field The invention relates to a coal tar processing method, in particular to a method for processing coal tar by combining alkali metal treatment and hydrocracking processes. Background The comprehensive utilization of coal tar resources has important significance for the value-added conversion of coal resources and the economic development of areas in China. The coal tar is a liquid product with pungent odor, which is a byproduct of the carbonization and gasification processes of coal, and can be classified into low-temperature coal tar, medium-temperature coal tar and high-temperature coal tar according to carbonization temperature. The coal tar is black or black brown viscous liquid at normal temperature, has high density and high content of metal, sulfur and other impurities, and has high oxygen content, especially high oxygen content of 30% in low-temperature coal tar, and the oxygen-containing compound is phenol and its derivative. The patent CN102851066A discloses a two-stage hydrogenation combined process method for coal tar, which comprises the steps of (a) feeding coal tar raw materials into a hydrogenation reaction section for hydrogenation reaction, (b) feeding separated liquid phase into a fractionating device for fractionation into gasoline fraction, diesel fraction and heavy fraction, c) feeding at least part of the heavy fraction obtained in the step (b) into a hydrocracking reaction section for hydrocracking reaction, (d) feeding reaction effluent of the hydrocracking reaction section into a thermal high-pressure separator for separation into gas phase and liquid phase, feeding at least part of the liquid phase into the hydrogenation reaction section of the step (a), and (e) mixing the gas phase obtained by separation of the thermal high-pressure separator in the step (d) and the diesel fraction obtained by fractionation in the step (b) into a diesel hydrogenation modification reaction section. Patent CN104927916a discloses a coal tar hydrotreating method, which comprises feeding hydrogen into coal tar through pores with average pore diameter of nanometer size to obtain hydrogen-containing coal tar, feeding the obtained hydrogen-containing coal tar into a tubular reactor, and contacting with hydrogenation catalyst filled in the tubular reactor under liquid phase hydrotreating condition. The method is characterized in that the conventional coal tar processing technology mainly comprises a two-stage hydrofining-hydrocracking process, a hydrocracking-hydrofining reverse-sequence tandem process, a delayed coking-fixed bed hydrogenation process and other hydrogenation technologies, and the problems of high oxygen content of coal tar, high water resistance requirement on the coal tar hydrogenation catalyst caused by water generated after hydrogenation, high bed blockage caused by high impurity and metal content of the coal tar, high pressure drop of the bed, influence on the operation period of a device and the like generally exist in the conventional coal tar hydrogenation process. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a coal tar processing method. The method organically combines alkali metal treatment and hydrocracking processes, and has excellent impurity removal effect, so that the quality of gasoline and diesel products is effectively improved, and the running period of the device is prolonged. A method for processing coal tar, the method comprising the steps of: (1) Mixing coal tar raw materials, alkali metal and hydrogen, and then entering an alkali metal treatment reaction zone for reaction; (2) Separating the reacted material obtained in the step (1); (3) And (3) the oil phase material obtained by separation treatment in the step (2) enters a hydrocracking reaction zone, and the reaction effluent is separated to obtain gas, gasoline, diesel oil and tail oil fractions. Further, in the step (1) of the method, the coal tar raw material is pretreated and then enters an alkali metal treatment reaction zone, the pretreatment process comprises dehydration and mechanical impurity removal treatment, the water content of the pretreated coal tar raw material is 0.5-3.0 wt%, preferably 1.0-2.5 wt%, the solid content is 0.05-0.35 wt%, preferably 0.10-0.20 wt%, the oxygen content is 2.0-20.0wt%, preferably 5.0-10.0 wt%, and the phenolic compound content is 10.0-35.0wt%, preferably 15.0-25.0 wt%. Further, in the step (1) of the method, the alkali metal is one or more of lithium, sodium and potassium, preferably sodium, and the mass ratio of the alkali metal to the coal tar raw material is (2.0-20.0) 100, preferably (8.0-15.0) 100. Furthermore, an auxiliary agent is also introduced in the step (1) of the method, wherein the auxiliary agent is alkali metal hydrosulfide, the alkali metal hydrosulfide comprises at least one of lithium hydrosulfide, sodium hydrosulfide and potassium hydrosulfide, preferably sodium hydrosu