CN114736708B

CN114736708B - Wax oil liquid phase hydrotreating method

Info

Publication number: CN114736708B
Application number: CN202110018651.3A
Authority: CN
Inventors: 曾榕辉; 刘涛; 张学辉; 桂兴华; 吴锐; 郭兵兵; 彭绍忠; 乔凯
Original assignee: China Petroleum and Chemical Corp; Sinopec Dalian Research Institute of Petroleum and Petrochemicals
Current assignee: Sinopec Dalian Petrochemical Research Institute Co ltd; China Petroleum and Chemical Corp
Priority date: 2021-01-07
Filing date: 2021-01-07
Publication date: 2023-07-04
Anticipated expiration: 2041-01-07
Also published as: CN114736708A

Abstract

The invention discloses a wax oil liquid phase hydrotreating method, which comprises the following steps: mixing wax oil raw material, light distillate oil and hydrogen in hydrogen dissolving equipment to dissolve hydrogen in liquid phase raw material; the liquid phase raw material of dissolved hydrogen is contacted with a hydrotreating catalyst to carry out hydrotreating reaction; separating the material after the hydrotreatment reaction to obtain a gas phase product, light distillate and heavy distillate, optionally recycling part or all of the light distillate to the hydrogen dissolving equipment, and taking the heavy distillate as a catalytic cracking raw material. The method can avoid excessive hydrogenation of heavy fraction when meeting the sulfur content of the catalytic cracking raw oil, and can obviously reduce the chemical hydrogen consumption.

Description

Wax oil liquid phase hydrotreating method

Technical Field

The invention belongs to the technical field of oil refining, relates to a wax oil liquid phase hydrogenation treatment method, and in particular relates to a method for producing a catalytic cracking raw material through a wax oil liquid phase hydrogenation process.

Background

While green energy technology is gaining increasing importance, oil extraction and utilization remains an important and short-term source of power fuels. The petroleum exploration reserves are increased year by year, but the heavy and inferior trends are obvious, so that more advanced technology needs to be developed to improve the utilization efficiency and clean production level of petroleum resources. In the oil refining technology, the hydrotreating technology and the catalytic cracking technology are important, the hydrotreating technology can reduce the contents of sulfur, nitrogen and metal in oil products and improve the content of hydrogen, the catalytic cracking technology can change macromolecules into micromolecules, namely, light products are produced by various raw materials, and if the two technologies are combined, high-quality clean products can be obtained. Catalytic cracking is an important means for producing light products from heavy raw materials, if wax oil which is not subjected to hydrotreatment is directly subjected to catalytic cracking, the operation conditions are more and more severe, the yields and product properties of light hydrocarbons, gasoline and the like are poorer and worse, and the catalytic cracking raw materials are subjected to hydrotreatment technology to remove impurities, so that the cracking performance of the feed is improved, the product distribution is improved, the selectivity of target products is improved, the yield of dry gas and coke is reduced, and the sulfur content in gasoline products is greatly reduced.

The conventional wax oil hydrotreating technology mainly comprises a conventional trickle bed hydrogen circulation hydrogenation technology and a liquid phase hydrogenation technology, wherein the liquid phase wax oil hydrogenation technology can meet the requirements of high-quality catalytic cracking raw materials under the condition of greatly reducing energy consumption. US6213835 and US6428686 disclose a hydrogenation process for pre-dissolving hydrogen, wherein the raw materials are relatively wide, not only wax oil raw materials, but also conventional liquid phase hydrogenation processes, namely, a part of high-pressure hydrogenation product streams subjected to liquid phase hydrogenation reaction is directly pressurized by a circulating pump and then used as circulating oil; CN104560132a discloses a continuous liquid phase wax oil hydrotreating method, CN104927902a discloses a wax oil hydrotreating method, which is more focused on the fact that hydrogen is dissolved in a wax oil raw material, a part of high-pressure hydrogenation material flow which is subjected to liquid phase hydrotreating reaction is directly pressurized by a circulating pump and then is used as circulating oil, and the rest part of the material flow enters a separator to be separated, namely, hydrotreating full fraction is used as circulating oil, namely, hydrogenation products are repeatedly circulated in a hydrogenation system, and excessive hydrogenation is generated when the sulfur content requirement of the wax oil hydrogenation products is met, namely, larger chemical hydrogen consumption is generated.

In summary, in the prior art, the conventional catalytic cracking process only limits the sulfur content, but does not require the hydrogen content, and if the hydrotreating process is deeply hydrogenated, excessive hydrogen consumption is caused by excessive hydrogenation. In the conventional wax oil liquid phase hydrotreating technology, in order to reduce energy consumption, the circulating oil used is a high-pressure hydrotreating product stream, namely a hydrotreating product oil stream which is the same as or similar to the range of the fraction of the raw oil.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a wax oil liquid phase hydrotreating method. The method adopts a liquid phase hydrogenation method, uses light fraction obtained by fractionation of hydrotreated produced oil as circulating oil to produce hydrogenated wax oil as a catalytic cracking raw material, optimizes the proportion of sulfur content in different fractions, avoids excessive hydrogenation of heavy fraction when the sulfur content of the catalytic cracking raw material oil is reached, and can obviously reduce chemical hydrogen consumption.

The invention relates to a wax oil liquid phase hydrotreatment method, which comprises the following steps:

mixing wax oil raw material, light distillate oil and hydrogen in hydrogen dissolving equipment to dissolve hydrogen in liquid phase raw material;

the liquid phase raw material of dissolved hydrogen is contacted with a hydrotreating catalyst to carry out hydrotreating reaction;

separating the material after the hydrotreatment reaction to obtain a gas phase product, light distillate and heavy distillate, optionally recycling part or all of the light distillate to the hydrogen dissolving equipment, and taking the heavy distillate as a catalytic cracking raw material.

In the method, the range of the fraction of the light distillate oil is 30-350 ℃, preferably 50-330 ℃, and more preferably 135-310 ℃.

In the above method, the initial boiling point of the heavy distillate is not less than 200 ℃, preferably not less than 220 ℃, and more preferably not less than 240 ℃.

In the method, the sulfur mass content in the heavy distillate is not more than 2500 mug/g, preferably not more than 2000 mug/g, and more preferably not more than 1000 mug/g.

In the method, part or all of the light fraction oil is recycled to the hydrogen dissolving equipment after being subjected to hydro-upgrading. In general, hydrotreating produces oils with higher light distillate densities and relatively lower cetane numbers that are not ideal diesel blending components. Experimental research shows that the light fraction obtained by fractionating the hydrotreated generated oil passes through a hydro-upgrading catalyst bed under the condition of liquid phase hydro-upgrading, so that the naphthenes in the light fraction can be subjected to hydro-ring opening, the density can be effectively reduced, the cetane number can be improved, and clean diesel oil products meeting high index requirements can be directly produced. That is, before the light distillate oil obtained by fractionation of the hydrotreated product oil is taken as the circulating oil, the hydro-upgrading reaction is carried out under the condition of liquid phase hydro-upgrading, the obtained hydro-upgrading product stream is taken as the circulating oil to be continuously mixed with the raw oil, and then the subsequent processing process is continuously carried out. Overall, the quality of the hydrotreated diesel can be remarkably improved through the supplementary processing means.

The invention relates to a wax oil liquid phase hydrotreating method, which specifically comprises the following steps:

(a) After being mixed with the hydroupgraded light distillate circulating oil, the wax oil raw oil is pressurized by a raw material pump and then enters a hydrogen dissolving tank in front of a hydrotreating reactor, and hydrogen is dissolved in the mixed oil in the hydrogen dissolving tank;

(b) The mixed material dissolved with hydrogen enters a hydrotreating reactor from a reactor inlet, and reacts under hydrotreating process conditions through one or more catalyst beds containing hydrotreating catalyst, and a hydrotreating generated material flow is obtained after the hydrotreating reaction;

(c) The hydrotreating generated material flow obtained by hydrotreating generated material flow is firstly separated to obtain a gas phase and a liquid phase which are rich in hydrogen, the separated liquid phase is fractionated to obtain light distillate and heavy distillate, and the heavy distillate is used as a raw material of a catalytic cracking device;

(d) And (c) mixing part of the light distillate oil obtained in the step (c) with hydrogen, passing through a hydro-upgrading catalyst bed layer under hydro-upgrading conditions, and returning the obtained hydro-upgrading light distillate oil as circulating oil to the hydrogen dissolving tank in the step (a).

In the method, the main fraction range of the wax oil raw oil is 300-600 ℃, and the asphaltene content is lower than 500 mu g/g. The wax oil raw oil can be obtained from petroleum refining or from a coal-to-oil process. For example, two-line reduction, three-line reduction and four-line reduction obtained on an atmospheric and vacuum device of the petroleum refining process, coker gas oil obtained on a coking device, light deasphalted oil obtained on a solvent deasphalting device, and the like; shale oil obtained by destructive distillation of oil shale; coal tar as a coal coking byproduct; the coal is indirectly liquefied to obtain synthetic oil; wax oil distillate oil obtained by directly liquefying coal; the mixed vacuum distillate may be obtained by mixing two or more of the above distillates at an arbitrary ratio.

In the method, the hydrogen dissolving tank is a specific device for contacting raw oil, circulating oil and hydrogen, and a facility for enhancing back mixing is arranged in the hydrogen dissolving tank to ensure that the hydrogen and the liquid are uniformly and fully mixed.

In the above method, the number of the hydrotreating reactors may be one or more. If a plurality of reactors are provided, a hydrogen dissolving tank is required to be arranged between the reactors.

In the above method, the mixture passing through the hydrogen dissolving tank can enter from the top of the hydrogenation reactor, and the mixture flow in which the hydrogen is dissolved passes through the catalyst bed layer from top to bottom. The wax oil raw oil and the circulating oil can enter from the bottom of the hydrogenation reactor after being mixed, and the mixture flow dissolved with hydrogen passes through the catalyst bed layer from bottom to top.

In the above method, the process parameters of the hydrotreating reaction are generally: the inlet pressure of the reactor is generally 3.0-21.0 MPa, and the total volume space velocity range of the fresh wax oil raw oil is 0.2h ^-1 ~7.0h ^-1 The weighted average reaction temperature of the full reaction zone ranges from 230 ℃ to 440 ℃, the temperature of the highest point of the catalyst bed layer is lower than 460 ℃, and the volume ratio of light distillate oil to fresh wax oil raw oil ranges from 0.4:1 to 8:1; the preferable process parameters are that the inlet pressure of the reactor is generally 4.0-20.0 MPa, and the total volume space velocity range of fresh wax oil raw oil is 0.3h ^-1 ~5.0h ^-1 The weighted average reaction temperature of the full reaction zone ranges from 260 ℃ to 430 ℃, the temperature of the highest point of the catalyst bed layer is lower than 450 ℃, and the volume ratio of light distillate oil to fresh wax oil raw oil ranges from 0.5:1 to 6:1.

In the above method, a certain amount of protecting agent may be filled in the raw oil inlet of the hydrogenation reactor, i.e. the mixture dissolved with hydrogen is first contacted with the protecting agent. The protecting agent is one conventional protecting agent, or two or more protecting agents may be selected according to the particle size from large to small, hydrogenation metal content from small to large, and hydrogenation performance from weak to strongForming a protective agent system. For example, three protectant systems FZC-100/FZC-105/FZC-106 (12/28/60 by volume) developed by FRIPP may be used herein. The total volume space velocity of fresh raw materials of the protective agent is generally 3.0h ^-1 ~30.0h ^-1 Preferably 4.0h ^-1 ~20.0h ^-1 。

In the method, the hydrotreating catalyst is a bifunctional catalyst, wherein the hydrogenation active component can be one or two or more of metals in a VIII group, such as W, mo, co, ni, the total content of the metal oxides is 5-75% based on the weight of the metal oxides, the carrier of the hydrotreating catalyst can be selected from alumina, amorphous silica-alumina, silica, titania and the like, and a part of auxiliary agents such as P, ti, zr, si, B and the like can be added into the catalyst. The hydrotreating catalyst used in the present process may be a commercially available catalyst, or a catalyst prepared by a preparation method disclosed in the art. If the hydrogenation active component of the catalyst is a sulfur state catalyst, the catalyst is used according to a normal start-up scheme. If the hydrogenation active component of the catalyst is in an oxidized state, the conventional pre-sulfiding treatment is carried out before the catalyst is used, namely, the hydrogenation active component of the catalyst is converted into a sulfided state in a reactor by a sulfiding start-up method, so that the catalyst has better hydrogenation performance. Commercially available hydrogenation catalysts are mainly 3936, 3996, CH-20, FF-14, FF-16, FF-18, FF-24, FF-26, FF-34, FF-46, FF-56, FF-66, FH-UDS series, FZC-41, FZC-42 and the like, HC-P, HC-T, HC-KUF-210/220 and the like, which are developed by UOP company, HR-406, HR-416, HR-448 and the like, ICR154, ICR174, ICR178, ICR179 and the like, TK-525, TK-555, TK-557 and the like, KF-752, KF-756, KF-757, KF-840, KF-848, KF-901, KF-907 and the like, which are developed by Topsor company.

In the above method, the catalyst bed provided in each reactor may be one catalyst bed or may be a plurality of catalyst beds. If a plurality of catalyst beds are arranged, hydrogen dissolving equipment is required to be arranged between the adjacent catalyst beds.

In the above method, the hydrogenation effluent obtained after the hydrogenation reaction is separated by a high-pressure separator and/or a low-pressure separator, and the high-pressure separator is not used in a preferred scheme. If a high pressure separator is used, the high pressure separator is a conventional gas-liquid separator. The hydrotreated reactant stream is separated in a high pressure separator to obtain a gas and a liquid. The low-pressure separator is a conventional gas-liquid separator. If a high-pressure separator is used, the liquid separated in the high-pressure separator is separated in a low-pressure separator to obtain gas and liquid. If a high pressure separator is not used, the hydrotreated reactant stream is separated directly in a low pressure separator to obtain a gas and a liquid.

In the above method, the fractionation system used for fractionation includes a stripping column and/or a fractionation column. And the liquid obtained by separation in the low-pressure separator is stripped and/or fractionated in a fractionating system to obtain light fraction and hydrogenated heavy fraction.

In the method, the light distillate oil hydro-upgrading operation conditions are as follows: the inlet pressure of the reactor is usually 3.0-21.0 MPa, the pressure is kept consistent with the hydrotreating pressure, and the total volume space velocity range of light distillate oil is 0.5h ^-1 ~6.0h ^-1 The weighted average reaction temperature range of the hydro-upgrading reaction zone is 230-410 ℃, and the temperature of the highest point of the catalyst bed layer is lower than 440 ℃.

In the method, the catalyst adopted in the hydro-upgrading of the light distillate is a conventional diesel hydro-upgrading catalyst, and the VIB metal and/or the VIII metal are/is generally used as active components, the VIB metal is/is generally Mo and/or W, and the VIII metal is/is generally Co and/or Ni. The carrier of the catalyst comprises one or more of alumina, silicon-containing alumina and molecular sieves, preferably contains the molecular sieves, and the molecular sieves can be Y-type molecular sieves. In a preferred embodiment, it contains, based on the weight of the catalyst, from 10 to 35wt% of a group VIB metal, calculated as oxide, from 3 to 15wt% of a group VIII metal, calculated as oxide, from 5 to 40wt% of a molecular sieve, from 10 to 80wt% of alumina; the specific surface area of the catalyst is100m ² /g～650m ² Per g, the pore volume is 0.15 mL/g-0.50 mL/g. The main commercial catalysts are 3963, FC-18, FC-32 catalysts developed by the petrochemical industry institute.

In the prior art, wax oil raw materials can be produced and hydrotreated to generate oil to provide raw materials for catalytic cracking through a liquid-phase circulation hydrogenation method, but the range of the fraction of the used circulating oil is generally equivalent to that of the raw oil, namely, the high-pressure full fraction obtained through hydrotreating is directly used as the circulating oil, and the applicant finds that when the circulating oil is adopted, heavy fraction in the circulating oil preferentially occupies active sites when passing through a catalyst bed layer, so that competitive adsorption occurs when heavy fraction to be reacted in the raw oil is reacted, and the hydrogenation reaction of the heavy fraction in the active sites is influenced, namely, the overall hydrogenation reaction effect of the heavy fraction is influenced; moreover, recycling of the heavy fraction can lead to excessive hydrogenation, i.e. to a corresponding increase in the hydrogen content when the same sulfur content is reached, resulting in an increase in the chemical hydrogen consumption. The research result shows that if light distillate oil with lower dry point is used as the circulating oil, hydrogen can be dissolved in the light distillate oil as well, and the requirement of hydrogen in the liquid phase circulating hydrogenation reaction process can be met, when macromolecules of the heavy distillate oil react preferentially, the molecular weight of the light distillate oil is smaller, the macromolecular reaction in the raw oil can not be influenced by competitive adsorption, and the diffusion, especially the internal diffusion, is less influenced, so that the hydrodesulfurization reaction of the macromolecules in the heavy distillate of the raw oil is facilitated, the macromolecules can be quickly separated from the surface of the catalyst, the excessive aromatic ring hydrogenation saturation reaction can not occur, and the overall performance is that the reaction efficiency is improved and the chemical hydrogen consumption is reduced on the premise that the sulfur content of the heavy distillate product meets the requirement.

Drawings

FIG. 1 is a flow chart of the liquid phase hydroprocessing method for wax oil according to the present invention.

FIG. 2 is another flow chart of the liquid phase hydroprocessing method for wax oil according to the present invention.

Wherein: 1-raw oil, 2-raw oil pump, 3-circulating oil, 4-hydrogen dissolving tank I, 5-new hydrogen, 6-hydrotreating reactor, 7-hydrotreating generated stream, 8-vent valve, 9-hydrotreating low-pressure separator, 10-hydrotreating low-pressure separator gas stream, 11-hydrotreating low-pressure separator liquid stream, 12-stripping/fractionating system, 13-stripping gas, 14-hydrotreating light distillate, 15-hydrotreating heavy distillate, 16-hydrogen dissolving tank II and 17-hydro-upgrading reactor.

Detailed Description

The process flow and the effects obtained by the liquid phase hydroprocessing method for wax oil according to the present invention are further described below with reference to examples, which are not to be construed as limiting the method according to the present invention.

The specific implementation mode of the wax oil liquid phase hydrotreatment method is as follows: raw oil 1 is mixed with circulating oil 3, the mixed material enters a hydrogen dissolving tank I, new hydrogen 5 is mixed with the mixed material in the hydrogen dissolving tank I and enters a hydrotreating reactor 6, hydrogen is dissolved in the effluent of the first catalyst bed layer through a first catalyst bed layer, hydrogen raw material is dissolved in the effluent of the second catalyst bed layer through a second catalyst bed layer, a hydrotreating generated material flow 7 of the effluent of the second catalyst bed layer enters a hydrotreating low-pressure separator 9 through a third catalyst bed layer, a hydrotreating low-pressure separator gas flow 10 and a hydrotreating low-pressure separator liquid flow 11 are obtained by separating in the hydrotreating low-pressure separator 9, the hydrotreating low-pressure separator liquid flow 11 enters a stripping/fractionating system 12, hydrotreating light distillate 14 and hydrotreating heavy distillate 15 are obtained by fractionating in the fractionating system under the effect of stripping gas, and 90wt% of the hydrotreating light distillate 14 is recycled as circulating oil 3, and the hydrotreating heavy distillate 15 is discharged from the device.

The following examples are provided to further illustrate the invention. All examples use FRIPP developed and produced hydrogenation protectant and hydrotreating catalyst, wherein FZC-105 and FZC-106 are two hydrogenation protectants, the appearance of which is four-leaf wheel shape, mo-Ni is used as hydrogenation active metal, wherein the total content of metal oxide of FZC-105 protectant is 6.7wt%, the total content of metal oxide of FZC-106 protectant is 9.5wt%, the filling volume ratio of the two hydrogenation protectants is 40:60, and for fresh wax oil raw material, the two hydrogenation protectants are two types of fresh wax oil raw materialThe total volume space velocity of the protective agent is 12.0h ^-1 The method comprises the steps of carrying out a first treatment on the surface of the The FF-56 hydrogenation pretreatment catalyst is selected, the shape of the catalyst is clover, mo-Ni is taken as hydrogenation active metal, and the total content of metal oxide is 30.3wt%.

TABLE 1 Main Properties of the feedstock

Table 2 example process conditions and main oil properties

The embodiment shows that the wax oil raw material can directly produce the hydrotreated heavy distillate oil meeting the sulfur content index requirement of the catalytic cracking raw material under the condition of lower hydrogen consumption by the liquid phase hydrotreating method of the technology.

Claims

1. A wax oil liquid phase hydrotreatment method is characterized in that: the method specifically comprises the following steps:

(c) The hydrogenation treatment generated material flow is firstly separated to obtain a gas phase and a liquid phase which are rich in hydrogen, the separated liquid phase is fractionated to obtain light distillate and heavy distillate, and the heavy distillate is used as a raw material of a catalytic cracking device;

(d) Mixing part of the light distillate oil obtained in the step (c) with hydrogen, passing through a hydro-upgrading catalyst bed layer under hydro-upgrading conditions, and returning the obtained hydro-upgrading light distillate oil as circulating oil to the hydrogen dissolving tank in the step (a);

wherein the fraction range of the hydro-upgrading light distillate oil is 30-350 ℃; the operating conditions for the hydrotreating reaction are as follows: the inlet pressure of the reactor is 3.0-21.0 MPa, and the total volume space velocity range of the fresh wax oil raw oil is 0.2h ^-1 ~7.0h ^-1 The weighted average reaction temperature of the full reaction zone ranges from 230 ℃ to 440 ℃, the temperature of the highest point of the catalyst bed layer is lower than 460 ℃, and the volume ratio of light distillate oil to fresh wax oil raw oil ranges from 0.4:1 to 8:1; the light distillate oil hydro-upgrading operation conditions are as follows: the inlet pressure of the reactor is 3.0-21.0 MPa, the pressure is kept consistent with the hydrotreating pressure, and the total volume space velocity range of the light distillate oil is 0.5h ^-1 ~6.0h ^-1 The weighted average reaction temperature range of the hydro-upgrading reaction zone is 230-410 ℃.

2. The method according to claim 1, characterized in that: the range of the wax oil raw oil fraction is 300-600 ℃, and the asphaltene content is lower than 500 mug/g.

3. The method according to claim 1, characterized in that: the initial distillation point of the heavy distillate is not less than 200 ℃.

4. The method according to claim 1, characterized in that: the sulfur content in the heavy distillate is not more than 2500 mug/g.

5. The method according to claim 1, characterized in that: the hydrogen dissolving tank is a specific device for contacting raw oil, circulating oil and hydrogen, and a facility for enhancing back mixing is arranged in the hydrogen dissolving tank to ensure that the hydrogen and the liquid are uniformly and fully mixed.

6. The method according to claim 1, characterized in that: the mixture passing through the hydrogen dissolving tank enters from the top of the hydrogenation reactor, and the mixture flow dissolved with hydrogen passes through the catalyst bed layer from top to bottom.