Hydrotreating device

Abstract

The utility model relates to the technical field of hydrotreatment, and discloses a hydrotreatment device which is used for treating reaction raw materials to obtain hydrogenated products. The hydrotreating device comprises a first-stage hydrogenation reaction unit and a middle-stage separation unit. The first-stage hydrogenation reaction unit is used for carrying out primary hydrofining on reaction raw materials; the effluent of the first-stage hydrogenation reaction unit enters the middle-stage reaction unit, the middle-stage separation unit comprises a first middle-stage separator and a second middle-stage separator, and the two middle-stage separators form two-stage middle-stage separation. The two-stage middle-section separation is arranged, so that the separation effect of the effluent of the first-section hydrogenation reaction unit is improved, light aromatic hydrocarbon in the first heavy component separated from the first middle-section separator can be further removed and is prevented from entering the subsequent hydrogenation reaction unit, and the stability and the production qualification rate of the process device are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of hydrotreating, in particular to a hydrotreating device for full-range crude benzene, heavy benzene, coal-based light hydrocarbons and / or coal tar. Background Art

[0002] In the existing hydrotreating, the reaction raw materials such as full-range crude benzene, heavy benzene, coal-based light hydrocarbons and / or coal tar can be refined and / or cracked by using a two-stage hydrotreating technology to obtain a product stream including product substances such as liquefied gas, refined light aromatics, hydrotreated naphtha, diesel blending components, etc. In the two-stage hydrotreating technology, the reaction raw materials are first subjected to hydrorefining in the first-stage hydrotreating reaction unit to complete the removal of heavy metals and olefin saturation, and to complete the removal of impurities such as desulfurization, denitrification and deoxidation of part of the raw materials, forming at least part of the product stream and the heavy components that have not been completely hydrorefined. The effluent of the first-stage hydrotreating reaction unit (i.e., the product stream and the heavy components that have not been completely hydrorefined formed in the first-stage hydrotreating reaction unit) is subjected to intermediate separation treatment, and light components and heavy components can be separated. Among them, the light components contain part of the product stream, and the heavy components will enter the second-stage hydrotreating reaction unit for thorough refining and cracking. In the intermediate separation treatment, a separator is used to separate the effluent of the first-stage hydrotreating reaction unit. However, the separation effect of only using one separator for the effluent of the first-stage hydrotreating reaction unit may be poor, which is significantly affected by conditions such as the component changes of the reaction raw material (one or more), the temperature, flow rate and pressure of the material entering the separator, so that there is still a considerable amount of light aromatics in the heavy components separated from the separator, resulting in poor energy consumption and stability of the whole device. Summary of the Utility Model

[0003] In order to solve the above technical problems, the utility model provides a hydrotreating device for treating reaction raw materials based on full-range crude benzene, heavy benzene, coal-based light hydrocarbons and / or coal tar.

[0004] The present disclosure provides a hydrotreating device for treating reaction raw materials to obtain hydrogenated products, including a first-stage hydrotreating reaction unit and an intermediate separation unit. The first-stage hydrotreating reaction unit is used for first hydrorefining the reaction raw materials; the intermediate separation unit includes a first intermediate separator and a second intermediate separator. The first intermediate separator is used for separating the effluent of the first-stage hydrotreating reaction unit to obtain a first light component and a first heavy component, and the second intermediate separator is used for separating the first heavy component flowing out of the first intermediate separator to obtain a second light component and a second heavy component. Among them, the reaction raw materials include any one, two, three or four of full-range crude benzene, heavy benzene, coal-based light hydrocarbons, and coal tar, and the hydrogenated products include at least the first light component and the second light component.

[0005] Preferably, the hydrotreating unit includes a product reflux drum, and the second light component enters the product reflux drum to separate out a first gaseous substance and a first liquid substance. More preferably, a cooler is provided at the gaseous substance outlet of the product reflux drum. The first gaseous substance flowing out of the product reflux drum is cooled by the cooler to form a second gaseous substance and a second liquid substance. The second gaseous substance is discharged, and the second liquid substance is refluxed to the product reflux drum.

[0006] Specifically, the first middle-stage separator is one of a rectifying column, a stripping column, a flash column, and a fractionating column, and the second middle-stage separator is one of a rectifying column, a fractionating column, an evaporation column, and a stripping column. Preferably, the second middle-stage separator is a rectifying column. The second middle-stage separator has a first inlet and a second inlet, and the first inlet is arranged higher than the second inlet. A flash drum is provided between the first middle-stage separator and the second middle-stage separator. The first heavy component is processed by the flash drum to form a gaseous substance and a liquid substance. The gaseous substance flowing out of the flash drum enters the first inlet of the second middle-stage separator, and the liquid substance flowing out of the flash drum enters the second inlet of the second middle-stage separator. Optionally, the hydrotreating unit includes a heat exchanger. Before the liquid substance flowing out of the flash drum enters the second inlet of the second middle-stage separator, it exchanges heat with the second heavy component in the heat exchanger.

[0007] In some embodiments, the hydrotreating unit further includes a second-stage hydrogenation reaction unit and a booster pump. The second heavy component is boosted by the booster pump and then enters the second-stage hydrogenation reaction unit for further hydrofining and hydrocracking. Among them, the hydrogenation product also includes the effluent flowing out of the second-stage hydrogenation reaction unit.

[0008] Specifically, the first-stage hydrogenation reaction unit includes a primary hydrogenation reactor, a secondary hydrogenation reactor, and a tertiary hydrogenation reactor. The reaction raw material sequentially passes through the primary hydrogenation reactor, the secondary hydrogenation reactor, and the tertiary hydrogenation reactor. Among them, the primary hydrogenation reactor is used to hydrogenate and saturate a part of the easily polymerizable substances in the reaction raw material; the secondary hydrogenation reactor is used to further hydrogenate and saturate the easily polymerizable substances in the reaction raw material and remove part of the sulfur and nitrogen in the reaction raw material; the tertiary hydrogenation reactor is used to continue removing sulfur and nitrogen in the reaction raw material and hydrogenating and refining heavy benzene.

[0009] Specifically, the second-stage hydrogenation reaction unit includes a quaternary hydrogenation reactor and a quinary hydrogenation reactor. The second heavy component is boosted by the booster pump and then sequentially enters the quaternary hydrogenation reactor and the quinary hydrogenation reactor; among them, the quaternary hydrogenation reactor is used to deeply hydrogenate and remove sulfur and nitrogen from a part of the second heavy component; the quinary hydrogenation reactor is used to hydrocrack a further part of the heavy components in the second heavy component after passing through the quaternary hydrogenation reactor and continue to deeply hydrogenate and remove sulfur and nitrogen.

[0010] Optionally, the hydrotreating unit further includes a high-pressure separator and a low-pressure separator. After the first light component and the effluent of the second-stage hydrotreating reaction unit are combined, they first pass through the high-pressure separator to remove excess hydrogen, and then pass through the low-pressure separator to remove hydrogen sulfide.

[0011] The hydrotreating unit of the present disclosure uses two middle-stage separators to form a two-stage middle-stage separation to separate the effluent of the first-stage hydrotreating reaction unit, and has the following obvious characteristics and advantages:

[0012] The present disclosure sets up a two-stage middle-stage separation, which is beneficial to improving the separation effect of the effluent of the first-stage hydrotreating reaction unit, can further remove the light aromatics in the first heavy component, avoid it entering the subsequent second-stage hydrotreating reaction unit, and improve the stability and production qualification rate of the process unit.

[0013] Setting up a two-stage middle-stage separation enables a wide range of raw material ratios in the entire hydrotreating system, further reduces the loss of aromatics, and can control the total aromatics loss of the hydrotreating system to be less than 1-5%, which is equivalent to traditional crude benzene hydrotreating, making its application scenarios more extensive; and further reduces hydrogen consumption, greatly saving hydrogen consumption and making the economic value of the system higher.

[0014] Setting up a two-stage middle-stage separation is beneficial to improving the separation effect of the effluent of the first-stage hydrotreating reaction unit, reducing the raw material processing load of the second-stage hydrotreating, and further reducing the energy consumption of the unit. At the same time, for the second-stage hydrotreating reaction unit, when the raw materials to be fed into the second-stage hydrotreating are reduced, it means that the processing capacity of the entire hydrotreating system equipment, especially the second-stage hydrotreating, is improved, reducing the processing cost while increasing the economic benefits of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present disclosure. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0016] Figure 1 Shows a schematic diagram of the hydrotreating unit of the present invention;

[0017] Figure 2 Shows Figure 1 The first-stage hydrotreating reaction unit in

[0018] Figure 3 Shows Figure 1 A middle-stage separation unit in

[0019] Figure 4 ShowsFigure 1 Another middle-section separation unit and a schematic diagram of the reaction process therein. Specific embodiments

[0020] The technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present disclosure without creative efforts shall fall within the scope of protection of the present disclosure.

[0021] The present utility model discloses a hydrotreating device and a supporting hydrotreating method, which can process any one, two, three or four of full-range crude benzene, heavy benzene, coal-based light hydrocarbons, and coal tar as reaction raw materials into a product stream, and the product stream includes product substances such as liquefied gas, refined light aromatics, hydrotreated naphtha, and diesel blending components.

[0022] The hydrotreating device and the hydrotreating method of the present utility model subject the reaction raw materials to the first-stage hydrotreating under high pressure, separate the heavy components and light components after separating the effluent of the first-stage hydrotreating through middle-section separation, and further subject the heavy components to the second-stage hydrotreating under high pressure. The product stream after the two-stage hydrotreating includes the light components in the effluent of the first-stage hydrotreating and the effluent of the second-stage hydrotreating. The first-stage hydrotreating is used for hydrogenation saturation treatment of easily polymerizable components such as diolefins and monoolefins in the reaction raw materials, and for hydrorefining treatment of the part in the reaction raw materials that is easy to remove heavy metals and impurities such as sulfur, nitrogen, and oxygen (especially the part of the reaction raw materials with lighter components). The second-stage hydrotreating is used for continuing the deep hydrodesulfurization and denitrification of the heavy components that have not been thoroughly hydrorefined in the previous stage to achieve hydrorefining treatment, and at the same time for hydrocracking treatment of some heavy components. In the first-stage hydrotreating, not only can heavy metals and impurities such as sulfur, nitrogen, and oxygen in the reaction raw materials be effectively removed, but also the coking and blockage conditions of the reaction raw materials during the hydrogenation process can be effectively alleviated. At the same time, deep hydrogenation treatment of heavy benzene in crude benzene can be carried out, and the hydrorefining effect of light aromatics can be achieved on the premise of ensuring low aromatic hydrocarbon loss.

[0023] See Figure 1, the hydrotreating unit 100 includes a first-stage hydrotreating reaction unit 80 and a middle-stage separation unit 110. Among them, the first-stage hydrotreating reaction unit 80 is used for the first hydrorefining of the reaction raw materials; the middle-stage separation unit 110 includes two middle-stage separators, namely the first middle-stage separator and the second middle-stage separator. After the reaction raw materials are first hydrorefined in the first-stage hydrotreating reaction unit 80, they enter the first middle-stage separator to separate out the first light components and the first heavy components; the first heavy components separated from the first middle-stage separator enter the second middle-stage separator to separate out the second light components and the second heavy components. The hydrogenation products at least include the first light components and the second light components. After passing through the second middle-stage separator, the light aromatics in the first heavy components can be effectively separated into the second light components, preventing this part of the light aromatics from entering the subsequent second-stage hydrotreating reaction unit.

[0024] In some embodiments, the hydrotreating unit 100 further includes a second-stage hydrotreating reaction unit 120, a material separation unit 90, a heat exchange or heating device, and some pipeline configurations for implementing the hydrotreating method of the present disclosure. The second heavy components enter the second-stage hydrotreating reaction unit 120 for further hydrorefining and hydrocracking, and the hydrogenation products further include the effluent of the second-stage hydrotreating reaction unit 120. The hydrotreating unit 100 and the corresponding hydrotreating method provided by the present invention are introduced in detail below.

[0025] It should be noted that the first-stage hydrotreating reaction unit 80 of the present disclosure may include two-stage, three-stage, four-stage, etc. hydrotreating reactions. The specific number of stages of the first-stage hydrotreating reaction unit 80 is not limited herein, as long as it can hydrorefine part of the reaction raw materials. The second-stage hydrotreating reaction unit 120 of the present disclosure may include one-stage, two-stage, three-stage, etc. hydrotreating reactions. The specific number of stages of the second-stage hydrotreating reaction unit 120 is not limited herein, as long as it can hydrorefine the second light components separated from the middle-stage separation unit 110. The following takes the first-stage hydrotreating reaction unit 80 as a three-stage hydrotreating reaction and the second-stage hydrotreating reaction unit 120 as a two-stage hydrotreating reaction as an example for detailed description.

[0026] Reaction raw materials

[0027] The reaction raw materials are raw materials containing crude benzene whole fraction, heavy benzene, coal-based light hydrocarbons, and coal tar.

[0028] In some embodiments, the reaction raw materials consist essentially of crude benzene whole fraction. For example, the density of crude benzene is 0.871 - 0.900 g / ml; the distillation range is that the initial boiling point > 70°C, the distillate before 180°C is greater than 93%; the total content of benzene, toluene, and xylene (total content of benzene, toluene, and xylene) ≥ 85%, benzene ≥ 68%; the total nitrogen content ≤ 8000 mg / kg, and the total sulfur content ≤ 8000 mg / kg.

[0029] In some embodiments, the reaction raw material consists essentially of heavy benzene. For example, the density of heavy benzene is 0.960 - 1.050 g / ml; the distillation range is 130°C - 300°C, the total nitrogen content ≤ 8000 mg / kg, and the total sulfur content ≤ 8000 mg / kg.

[0030] In some embodiments, the reaction raw material consists essentially of coal-based light hydrocarbons. For example, the density of coal-based light hydrocarbons is 0.760 - 0.820 g / ml; the distillation range is 35 - 185°C, the content of benzene, toluene and xylene ≥ 35%, and the diolefin content < 11 gI2 / 100g.

[0031] In some embodiments, the reaction raw material consists essentially of coal tar, especially light coal tar. For example, the density of coal tar is 0.980 - 1.170 g / ml; the distillation range is 150 - 380°C; the total nitrogen content ≤ 8000 mg / kg, and the total sulfur content ≤ 8000 mg / kg.

[0032] In some embodiments, the reaction raw material is any one or two or three or four of crude benzene whole fraction, heavy benzene, coal-based light hydrocarbons and coal tar. For example, the crude benzene whole fraction and coal-based light hydrocarbons are used as the reaction raw material in a mass ratio of 1:4; the coal-based light hydrocarbons, heavy benzene, crude benzene and light coal tar are used as the reaction raw material in a mass ratio of 3:4:8:5 respectively; the heavy benzene and light coal tar are used as the reaction raw material in a mass ratio of 1:2.

[0033] Two-stage hydrogenation and mid-section separation

[0034] The reaction raw material is subjected to first-stage hydrogenation treatment. The effluent after the first-stage hydrogenation treatment is separated by middle-stage separation treatment to separate out heavy components and light components, and then the separated heavy components are subjected to second-stage hydrogenation treatment. The pressure range of the first-stage hydrogenation treatment is 4 - 15 Mpa, the pressure range of the middle-stage separation treatment is 4 - 15 Mpa, and the pressure range of the second-stage hydrogenation treatment is 4 - 15 Mpa.

[0035] First-stage hydrogenation treatment

[0036] Specifically, in the first-stage hydrogenation treatment, the reaction raw material sequentially undergoes primary hydrogenation reaction, secondary hydrogenation reaction and tertiary hydrogenation reaction. The reaction raw material undergoes hydrofining in the three-stage hydrogenation reaction to complete the removal of heavy metals and olefin saturation, and to complete the removal of impurities such as desulfurization, denitrification and deoxidation of part of the reaction raw material, forming at least part of the product stream and the heavy components that have not been completely hydrofined.

[0037] Specifically, the reaction raw material 11 is mixed with hydrogen (for example, the recycled hydrogen after supplementing fresh hydrogen) and then used as the inflow 12 for the first-stage hydrogenation treatment. The first-stage hydrogenation treatment is mainly carried out in the first-stage hydrogenation reaction unit 80, and the reaction raw material 11 undergoes three-stage hydrogenation reaction in the first-stage hydrogenation reaction unit 80. SeeFigure 2 The first - stage hydrogenation reaction is liquid - phase pre - hydrogenation, and the first NiMo catalyst is selected. The effluent 14 of the first - stage hydrogenation reaction serves as the influent of the second - stage hydrogenation reaction. The second - stage hydrogenation reaction is gas - liquid two - phase hydrogenation, and the second NiMo catalyst is selected. The effluent 15 of the second - stage hydrogenation reaction serves as the influent of the third - stage hydrogenation reaction. The third - stage hydrogenation reaction is gas - phase hydrogenation, and one, two, or three of the third NiMo catalyst, the first CoMo catalyst, and the first NiMoW catalyst are selected. The hydrogen added to the reaction raw materials includes recycle hydrogen 63 and make - up hydrogen 62. Among them, the recycle hydrogen 63 refers to the excess hydrogen separated from the first light component 41 separated after the first - stage hydrogenation treatment and the effluent 44 after the second - stage hydrogenation treatment. The recycle hydrogen 63 and the make - up hydrogen 62 are transported through pipeline 61 and then mixed with the reaction raw materials 11.

[0038] More specifically, the operating conditions of the first - stage hydrogenation treatment are as follows: the system pressure is 4 - 15 Mpa, preferably 5 - 12 Mpa, and more preferably 5.5 - 11 Mpa. Among them, the temperatures of the influents of the first - stage hydrogenation reaction, the second - stage hydrogenation reaction, and the third - stage hydrogenation reaction increase in sequence, which can increase from 90 °C to about 400 °C, and the difference between adjacent two - stage can be about dozens to more than one hundred degrees Celsius.

[0039] Reference Figure 1 and Figure 2 The reaction raw materials 11 enter the buffer tank D - 1 for mixing and buffering, and then are pressurized to 5 - 15 Mpa by the feed pump P - 1. After the reaction raw materials 11 are mixed with excessive hydrogen, they are heated to 60 - 180 °C and enter the first - stage hydrogenation reactor R - 1. The first NiMo catalyst is arranged in the first - stage hydrogenation reactor R - 1. In some embodiments, the first - stage hydrogenation reactor R - 1 can be a shell - and - tube fixed - bed reactor or an adiabatic fixed - bed reactor, and preferably an adiabatic fixed - bed reactor. The reaction raw materials contact the first NiMo catalyst in the first - stage hydrogenation reactor R - 1 to achieve liquid - phase pre - hydrogenation. In some embodiments, a protective agent is also arranged in the first - stage hydrogenation reactor R - 1. This protective agent is a catalyst with a special structure containing a small amount of active metal. The reaction raw materials first pass through the protective agent and then through the first NiMo catalyst.

[0040] The effluent 14 of the first-stage hydrogenation reaction is heated to 150 - 250 °C and enters the second-stage hydrogenation reactor R-2, where the second NiMo catalyst is disposed. In some embodiments, the second-stage hydrogenation reactor R-2 can be a reactor operating in a fixed bed, moving bed or fluidized bed, preferably a fixed bed reactor, more preferably an adiabatic fixed bed reactor. The effluent 14 of the first-stage hydrogenation reaction contacts the second NiMo catalyst in the second-stage hydrogenation reactor R-2 to achieve gas-liquid two-phase hydrogenation. In some embodiments, a protective agent and / or a demetallizing agent are also provided in the second-stage hydrogenation reactor R-2. In a preferred embodiment, the effluent 14 of the first-stage hydrogenation reaction passes through the protective agent, the demetallizing agent, and the second NiMo catalyst in sequence, and the effluent removes trace impurities before undergoing the second-stage hydrogenation reaction.

[0041] The effluent 15 of the second-stage hydrogenation reaction is heated to 200 - 395 °C and enters the third-stage hydrogenation reactor R-3 to contact the catalyst, achieving gas-phase hydrogenation and completing the third-stage hydrogenation reaction for hydrogenating and removing sulfur, nitrogen, and oxygen impurities to a certain depth. The catalyst can be selected from one, two, or three of the third NiMo catalyst, the first CoMo catalyst, and the first NiMoW catalyst. In some embodiments, the third-stage hydrogenation reactor R-3 can be a reactor operating in a fixed bed, moving bed or fluidized bed, preferably a fixed bed reactor, more preferably an adiabatic fixed bed reactor.

[0042] In some embodiments, the entire interior of the third-stage hydrogenation reactor R-3 is the first CoMo catalyst. Under the action of hydrogenation at a relatively high temperature, the effluent 15 of the second-stage hydrogenation reaction completes the deep hydrogenation and removal of sulfur, nitrogen, and oxygen impurities of all components.

[0043] In some embodiments, the third NiMo catalyst and the first NiMoW catalyst are selected in the third-stage hydrogenation reactor R-3. Under the action of hydrogenation at a relatively low temperature, the effluent 15 of the second-stage hydrogenation reaction completes the deep hydrogenation and removal of sulfur, nitrogen, and oxygen impurities of all components.

[0044] Optionally, two of the first CoMo catalyst and the first NiMoW catalyst are selected in the third-stage hydrogenation reactor R-3. Optionally, three of the third NiMo catalyst, the first CoMo catalyst, and the first NiMoW catalyst are selected in the third-stage hydrogenation reactor R-3. In some embodiments, a protective agent and / or a demetallizing agent are also provided in the third-stage hydrogenation reactor R-3. In a preferred embodiment, the effluent 15 of the second-stage hydrogenation reaction passes through the protective agent, the demetallizing agent, the third NiMo and / or the first CoMo catalyst, and the first NiMoW catalyst in sequence, so that the effluent removes trace impurities before undergoing the third-stage hydrogenation reaction.

[0045] In the first-stage hydrotreating, the hydrogenation reaction gradually, stepwise, and in sections achieves the hydrorefining of some reaction raw materials. The first NiMo catalyst used in the first-stage hydrogenation reaction has a high active metal content, enabling it to have characteristics such as relatively high reaction activity and a low reaction activation temperature (80 - 120 °C). The second NiMo catalyst used in the second-stage hydrogenation reaction has a slightly lower active metal content, which can not only ensure the smooth progress of the reaction raw materials in the second-stage hydrogenation reaction but also ensure a low aromatic hydrocarbon loss rate. The upper-layer catalyst used in the third-stage hydrogenation reaction can complete the hydrorefining such as desulfurization, denitrification, and deoxidation of light benzene and part of heavy benzene on the premise of ensuring the minimum aromatic hydrocarbon loss. At the same time, a lower-layer catalyst with stronger reaction activity is also arranged in the third-stage hydrogenation reactor to ensure sufficient hydrogenation depth to complete the refining and impurity removal of macromolecular substances in heavy benzene.

[0046] See Figure 2 , in some embodiments, the effluent 14 of the first-stage hydrogenation reaction first undergoes a protective reaction treatment to remove easily coking substances and then undergoes a second-stage hydrogenation reaction. The first-stage hydrotreating unit 80 is provided with a protective reactor MR-1. The protective reactor MR-1 is filled with porcelain balls and porous protective agents, which can effectively remove easily coking substances. For example, asphaltenes and resins carried in the reaction raw materials and olefin polymers formed by a small amount of side reactions during the hydrogenation heating process, thereby prolonging the coking time of the second-stage hydrogenation reactor. In some embodiments, the first-stage hydrotreating unit 80 is provided with two protective reactors MR-1 arranged in parallel, one is in operation and the other is in standby, further reducing the frequency of local blockage of the device and also enabling on-line treatment of the blocked position, reducing the impact on production.

[0047] In some embodiments, the first-stage hydrotreating also includes a dechlorination treatment of the effluent 16 of the third-stage hydrogenation reaction (i.e., the effluent of the first-stage hydrotreating, referred to as the third-stage effluent). The first-stage hydrotreating unit 80 includes a dechlorination reactor R-6. The dechlorination reactor R-6 is filled with a dechlorinating agent, which can remove hydrogen chloride generated in the first-stage hydrotreating, effectively avoiding the corrosion of pipelines and equipment by hydrogen chloride.

[0048] Mid-section separation treatment

[0049] See Figure 1 , Figure 3, specifically, in some embodiments, the middle-stage separation unit 110 includes a first middle-stage separator C-6 and a second middle-stage separator C-7. The effluent 16 from the first-stage hydrogenation reaction unit 80 is separated in the first middle-stage separator C-6 into a first light component 41 and a first heavy component 112, and the first heavy component 112 enters the second middle-stage separator C-7 to be separated into a second light component 118 and a second heavy component 42. The setting of two middle-stage separators to form a two-stage middle-stage separation is beneficial to improving the separation effect of the effluent 16 from the first-stage hydrogenation reaction unit 80, can further remove the light aromatics in the first heavy component 112, prevent it from entering the subsequent second-stage hydrogenation reaction unit 120, and improve the stability and production qualification rate of the process unit.

[0050] The hydrogenation products include a first light component 41 and a second light component 118, and the second heavy component 42 continues to enter the second-stage hydrogenation reaction unit 120 for hydrorefining and hydrocracking to form the effluent 44 of the second-stage hydrogenation reaction unit 120. The gaseous and liquid substances are separated from the second light component 118, and the liquid substance is the product stream 47a. After the first light component 41 and the effluent 44 of the second-stage hydrogenation reaction unit 120 are combined, excess hydrogen and hydrogen sulfide are removed through high-low pressure separation to form the product stream 47b.

[0051] Specifically, the first middle-stage separator C-6 is specifically a tower, such as one of a distillation column, a stripping column, a flash column, and a fractionating column. The recycle hydrogen 63 flows into the bottom of the middle-stage separator C-6 through the pipeline 64. The recycle hydrogen 63 serves as a stripping medium for separating the effluent 16 from the three-stage hydrogenation reaction in the first middle-stage separator C-6 into a first light component 41 and a first heavy component 112. The light component 41 flowing out from the top of the first middle-stage separator C-6 includes light aromatics and recycle hydrogen, and the light aromatics are rich in benzene, toluene, and xylene.

[0052] In a preferred embodiment, the recycle hydrogen 63 for stripping is heated, for example, heated to 200 - 450 °C, so as to obtain a better stripping effect and make the first light component more fully separated from the first heavy component. See Figure 1 , and the recycle hydrogen 63 for stripping is transported through the pipeline 64 to the second hydrogenation heater F-2, heated to 200 - 450 °C, and then flows into the first middle-stage separator C-6.

[0053] In some embodiments, to ensure the qualified rate of products in the product streams of the two-stage hydrogenation reaction and to minimize the entrainment of unqualified heavy components that have not completed the hydrodesulfurization and denitrification reactions in the light components separated from the top of the first middle-stage separator C-6, a cold reflux liquid is introduced into the top of the first middle-stage separator C-6 to provide sufficient mass transfer conditions for the gas-liquid two-phase. Specifically, the cold reflux liquid can be hydrogenated tail oil, diesel blending components, hydrotreated naphtha separated from the product stream, or it can also be diesel, or a mixture of hydrogenated tail oil and diesel. Among them, the hydrogenated tail oil is the effluent 37 from the bottom of the fractionating tower C-3, which will be specifically introduced later. In a preferred embodiment, the cold reflux liquid is hydrogenated tail oil, and after being cooled to 30-120 °C, it flows into the first middle-stage separator C-6. Injecting the hydrogenated tail oil into the first middle-stage separator C-6 can also separate the part of the hydrogenated tail oil that has not removed sulfur and nitrogen impurities into the first heavy components and re-perform the second-stage hydrogenation treatment, thereby completing the deep hydrogenation reaction, completely removing sulfur and nitrogen impurities, and to a certain extent, performing hydrocracking to reduce its specific gravity.

[0054] Specifically, the second middle-stage separator C-7 is one of a rectifying tower, a fractionating tower, an evaporation tower, and a stripping tower. Optionally, the middle-stage separation unit 110 includes a first booster pump P-2, and the second heavy components enter the second-stage hydrogenation reaction unit after being boosted by the first booster pump P-2. In a preferred embodiment, the middle-stage separation unit 110 further includes a product reflux tank D-9, and the second light components 118 are further separated into a first gaseous substance and a first liquid substance in the product reflux tank D-9. Since the first gaseous substance contains a large amount of hydrogen sulfide, in some embodiments, the first gaseous substance is directly discharged, and the remaining first liquid substance is the product stream 47a. In some other embodiments, referring to Figure 4 , the first gaseous substance is further separated into a second gaseous substance and a second liquid substance after being cooled, the second gaseous substance is discharged, and the first liquid substance and the second liquid substance are mixed to form the product stream 47a.

[0055] Referring to Figure 1 and Figure 4, specifically, the middle section separation unit 110 includes a cooler E-11. The product reflux drum is provided with a gaseous substance outlet, and the cooler E-11 is arranged at the gaseous substance outlet of the product reflux drum. The first gaseous substance flowing out of the product reflux drum D-9 forms a second gaseous substance and a second liquid substance after being cooled by the cooler E-11. The second gaseous substance is hydrogen sulfide, which is discharged, and the second liquid substance flows back to the product reflux drum D-9. The cooling medium of the cooler E-11 can adopt industrial circulating water, low-temperature chilled water or other cooling media and materials. Preferably, the cooling medium adopts low-temperature chilled water. The non-condensable gas (the first gaseous substance) at the top of the second middle section separator C-7 still contains a small amount of light benzene components, and the light benzene therein can be condensed from the gas phase into the liquid phase through the cooler E-11 and returned to the product reflux drum D-9, reducing the product being carried out by the dry gas (hydrogen sulfide) and improving the total yield.

[0056] Continue to refer to Figure 4 , preferably, the second middle section separator C-7 is a distillation column. More preferably, the distillation column adopts efficient separation internals, including components such as trays, packings or separators, which can make the light benzene content (benzene, toluene) in the bottom of the column <0.01%, and the top of the column does not contain heavy components and is a fully hydrogenated qualified light component. The following takes the second middle section separator C-7 as a distillation column as an example for illustration.

[0057] Specifically, the second middle section separator C-7 has a first inlet and a second inlet, and the first inlet is arranged higher than the second inlet. The middle section separation unit 110 includes a flash drum D-10, and the flash drum D-10 is arranged between the first middle section separator C-6 and the second middle section separator C-7. The first heavy component 112 forms a gaseous substance 114 and a liquid substance 116 after being processed by the flash drum D-10. The gaseous substance 114 flows out from the top of the flash drum D-10 and enters the first inlet of the second middle section separator C-7, and the liquid substance 116 flows out from the bottom of the flash drum D-10 and enters the second inlet of the second middle section separator C-7. The pressure in the first middle section separator C-6 is relatively high, and a small amount of light hydrocarbons and non-condensable gas are dissolved in the bottom oil of the first middle section separator C-6 to form the first heavy component. The pressure in the second middle section separator C-7 is relatively low, being 0.1-2.0 Mpa. Before the first heavy component enters the second middle section separator C-7, it first enters the flash drum D-10, flashing the light hydrocarbons and non-condensable gas dissolved in the oil product into the upper middle part of the second middle section separator C-7 in the form of gas phase, while the lower oil phase enters the middle part of the second middle section separator C-7, making the component distribution in the tower of the second middle section separator C-7 more uniform, thereby reducing the energy consumption during the separation of the second middle section separator C-7 and then reducing the energy consumption of the entire system.

[0058] In particular, the middle-stage separation unit 110 includes a heat exchanger E-10. Before the liquid-phase material flowing out of the flash tank D-10 enters the second inlet of the second middle-stage separator C-7, it first exchanges heat with the second heavy components in the heat exchanger E-10. After the second heavy components 42 flow out of the second middle-stage separator C-7, they serve as a heat source to provide heat for the liquid-phase material 116 flowing out of the flash tank D-10. After absorbing heat, the liquid-phase material 116 enters the second middle-stage separator C-7. The setting of the heat exchanger E-10 can further reduce the energy consumption of the second middle-stage separator C-7. By feeding the gas-liquid phases separately into the second middle-stage separator C-7 and achieving sufficient thermal coupling, not only is the separation accuracy high but also the energy consumption is low. Optionally, the second heavy components 42 first enter the heat exchanger E-10 after being pressurized by the first booster pump P-2.

[0059] The working pressure of the first middle-stage separator C-6 is relatively high, which can achieve the preliminary separation of the first-stage hydrogenation products, separate most of the light components (aromatics) from the top of the tower, and recycle the separated recycle hydrogen for subsequent use. The second middle-stage separator C-7 fully separates the residual light components (aromatics) in the heavy components at the bottom of the first middle-stage separator C-6, so that the raw materials entering the second-stage hydrogenation have no / extremely low content of light components (aromatics).

[0060] In addition, the setting of two middle-stage separators enables a wide range of raw material ratios in the entire hydrogenation system, further reducing the loss of aromatics. The total aromatics loss of the hydrogenation system can be controlled to be less than 1-5%, which is equivalent to that of traditional crude benzene hydrogenation, making its application scenarios more extensive; and further reducing the hydrogen consumption, greatly saving the hydrogen consumption and making the economic value of the system higher.

[0061] The setting of two middle-stage separators is beneficial to improving the separation effect of the effluent 16 of the first-stage hydrogenation reaction unit 80, reducing the raw material processing load of the second-stage hydrogenation, and further reducing the energy consumption of the device. At the same time, for the second-stage hydrogenation reaction unit, when the raw materials to be fed into the second-stage hydrogenation are reduced, it means that the processing capacity of the entire hydrogenation system equipment, especially the second-stage hydrogenation, is improved, reducing the processing cost and increasing the economic benefits of the device.

[0062] The setting of two middle-stage separators is also applicable to the hydrogenation equipment for processing aromatic compounds without light benzene (benzene, toluene). The second middle-stage separator C-7 can further remove the light components in the raw materials for the second-stage hydrogenation on the basis of the first middle-stage separator C-6, so that the hydrocracking and cracking reactions in the second-stage hydrogenation only process the heavy components, and the light components will not cause the light components to be cracked into lower-value C1-C4 dry gas due to the entry of light components.

[0063] Second-stage hydrogenation treatment

[0064] The second-stage hydrotreating enables the second heavy fraction 42 to successively undergo a four-stage hydrogenation reaction and a five-stage hydrogenation reaction. The second heavy fraction 42 completes hydrorefining through deep hydrodesulfurization and denitrification in the hydrogenation reactions of these two stages, and at the same time, partially hydrogenates some of the second heavy fraction (for example, coal tar components) into high-value-added diesel blending components, hydrotreated naphtha, etc.

[0065] Specifically, the second heavy fraction 42 enters the four-stage hydrogenation reaction and the five-stage hydrogenation reaction after being pressurized and heated. The four-stage hydrogenation reaction is a gas-phase hydrogenation, and a heavy aromatic hydrogenation catalyst is selected, such as the fourth NiMo catalyst and / or the second NiMoW catalyst, etc. The five-stage hydrogenation reaction is a gas-phase hydrogenation, and a hydrocracking agent and a heavy aromatic hydrogenation catalyst are selected. The hydrocracking agent can be at least one of Ni-W, Ni-Mo-P, or "Y-type" molecular sieve, and the heavy aromatic hydrogenation catalyst can be the fifth NiMo catalyst and / or the third NiMoW catalyst, etc.

[0066] Continue to refer to Figure 1 , the hydrotreating unit 100 is provided with a second-stage hydrogenation reaction unit 120, and the second-stage hydrogenation reaction unit 120 includes a four-stage hydrogenation reactor R-4 and a five-stage hydrogenation reactor R-5. The heavy fraction 42 is pressurized to 4-15 Mpa by the first booster pump P-2 and then heated to more than two hundred to nearly four hundred degrees Celsius and then enters the four-stage hydrogenation reactor R-4. In some embodiments, the four-stage hydrogenation reactor R-4 can be a reactor operating in a fixed bed, moving bed, or fluidized bed, preferably a fixed bed reactor, and more preferably an adiabatic fixed bed reactor. The four-stage hydrogenation reactor R-4 is provided with the fourth NiMo catalyst and / or the second NiMoW catalyst, and the second heavy fraction 42 contacts the aforementioned catalyst to achieve deep hydrodesulfurization and denitrification.

[0067] The effluent 43 from the fourth-stage hydrogenation reaction flows into the fifth-stage hydrogenation reactor R-5. The hydrocracking agent and the fifth NiMo catalyst and / or the third NiMoW catalyst are disposed in the fifth-stage hydrogenation reactor R-5, and the reaction temperature is three hundred to over four hundred degrees Celsius. In some embodiments, the fifth-stage hydrogenation reactor R-5 can be a reactor operating in a fixed bed, moving bed, or fluidized bed, preferably a fixed bed reactor, and more preferably an adiabatic fixed bed reactor. In a preferred embodiment, the hydrocracking agent is disposed in the upper layer of the heavy aromatic hydrocarbon hydrogenation catalyst. The effluent 43 from the fourth-stage hydrogenation reaction first contacts the hydrocracking agent for hydrocracking and then contacts the fifth NiMo catalyst and / or the third NiMoW catalyst for deep hydrodesulfurization and denitrification. The first light component 41 and the effluent 44 from the fifth-stage hydrogenation reaction (the effluent from the second-stage hydrogenation treatment, hereinafter referred to as the second-stage hydrogenation effluent) are transported to the high-pressure separator D-2 through the pipeline 45. Since the reaction activity and cracking degree of the hydrocracking agent are very strict for the setting of the reaction temperature, in order to achieve an ideal cracking effect, its temperature is preferably higher than the temperature set for the fourth-stage hydrogenation reaction; however, too high a reaction temperature is extremely likely to cause a "temperature runaway" in the catalyst bed and result in a safety accident, so its temperature is preferably lower than the end temperature of the fifth-stage hydrogenation reaction (above 380 °C). Therefore, the hydrocracking agent is disposed in the relatively lower-temperature upper part of the last fifth-stage hydrogenation reactor R-5. In a preferred example, the cracking agent is selected from the NiW catalyst and / or the NiMoP catalyst with relatively better cracking depth and selectivity to maintain moderate cracking and a high target product recovery rate.

[0068] In some embodiments, there is no limitation on the active metal content selected for the fourth NiMo catalyst and the fifth NiMo catalyst, nor is there any limitation on the active metal content selected for the second NiMoW catalyst and the third NiMoW catalyst. For example, they can be the same or different. Since the hydrogenation reaction of the second heavy component 42 is dispersed into the fourth-stage hydrogenation reactor R-4 and the fifth-stage hydrogenation reactor R-5, the heat released by the reaction is dispersed into the two reactors, which is beneficial to the temperature control in the two reactors, thus ensuring the safety of the system.

[0069] In some embodiments, the second heavy component 42 is first mixed with hydrogen and then undergoes the second-stage hydrogenation treatment. For example, the second heavy component 42 is mixed with the recycled hydrogen 63 transported through the pipeline 65. In some embodiments, hydrogen (not shown in the figure) can be directly input into the fourth-stage hydrogenation reactor R-4 and the fifth-stage hydrogenation reactor R-5, such as the recycled hydrogen 63, to supplement the hydrogen required for the reaction or control the reaction temperature.

[0070] In the second-stage hydrotreating, the hydrogenation reaction proceeds step by step and stage by stage according to a temperature gradient, and the heavy fraction materials that have not been thoroughly desulfurized and denitrified are thoroughly hydrorefined and cracked. The fourth-stage hydrogenation reaction uses the fourth NiMo catalyst and / or the second NiMo catalyst with a relatively lower active metal content than the fifth-stage hydrogenation reaction to conduct a part of the hydrorefining reaction on the second heavy fraction in the early stage, and maintain the heat released by the reaction within a certain controllable range to prevent a "temperature runaway" in the reactor bed and avoid safety accidents.

[0071] Material heat exchange

[0072] In some embodiments, the effluent 16 of the third-stage hydrogenation reaction exchanges heat with at least one of the influent of the first-stage hydrogenation reaction, the influent of the second-stage hydrogenation reaction, and the influent of the third-stage hydrogenation reaction. In the three-stage hydrotreating, the temperature of each stage increases continuously, and the hydrogenation reaction is an exothermic reaction. The temperature of the effluent 16 of the third-stage hydrogenation reaction can be close to 400 °C. Therefore, this effluent can provide heat energy for the influents of the first-stage, second-stage, and third-stage hydrogenation reactions. In a preferred embodiment, the effluent 16 of the third-stage hydrogenation reaction provides heat energy for the influents of the first-stage, second-stage, and third-stage hydrogenation reactions. In a more preferred embodiment, the effluent 16 of the third-stage hydrogenation reaction first exchanges heat with the influent of the third-stage hydrogenation reaction, then exchanges heat with the influent of the second-stage hydrogenation reaction, and finally exchanges heat with the influent of the first-stage hydrogenation reaction. In some embodiments, the effluent 16 of the third-stage hydrogenation reaction is subjected to dechlorination treatment before exchanging heat with the influents of each stage of the hydrogenation reaction.

[0073] In some embodiments, the influents of the first-stage, second-stage, and third-stage hydrogenation reactions can also be heated to the corresponding temperature by a heater before the hydrogenation reaction. For example, the influent of the first-stage hydrogenation reaction can be heated to 60-180 °C by a heater. Preferably, referring to Figure 1 , Figure 2 , at the beginning or end of the process flow, the influent of the first-stage hydrogenation reaction is heated by heater E-2 before the first-stage hydrogenation reaction. At the beginning or end of the process flow, when the effluent 16 of the third-stage hydrogenation reaction cannot provide sufficient heat energy for the influent of the first-stage hydrogenation reaction, the heater E-2 can provide heat energy.

[0074] Continue to refer to Figure 1 , Figure 2, the hydrotreating unit 100 further includes a first heat exchanger E-1, a second heat exchanger E-3, and a third heat exchanger E-4. The first heat exchanger E-1 is used for heat exchange between the inflow of the first-stage hydrotreating reaction and the outflow 16 of the third-stage hydrotreating reaction; the second heat exchanger E-3 is used for heat exchange between the inflow of the second-stage hydrotreating reaction and the outflow 16 of the third-stage hydrotreating reaction; the third heat exchanger E-4 is used for heat exchange between the inflow of the third-stage hydrotreating reaction and the outflow 16 of the third-stage hydrotreating reaction. The outflow 16 of the third-stage hydrotreating reaction sequentially passes through the third heat exchanger E-4, the second heat exchanger E-3, and the first heat exchanger E-1. In some embodiments, the hydrotreating system 100 is further provided with a heater E-2 for providing heat energy to the inflow of the first-stage hydrotreating reaction. Specifically, the heater E-2 is an electric heater or an externally supplied heat source heater, which is started at the beginning or end of the process flow. In some embodiments, the hydrotreating unit is provided with a sixth heat exchanger E-7 for heat exchange between the inflow 12 of the first-stage hydrotreating reaction, the first light component 41, and the outflow 44 of the fifth-stage hydrotreating reaction. In a preferred embodiment, the inflow 12 of the first-stage hydrotreating reaction flows into the first-stage hydrotreating reactor R-1 after passing through the first heat exchanger E-1, the sixth heat exchanger E-7, and the heater E-2 in sequence.

[0075] Reference Figure 2 , in some embodiments, the outflow 15 of the second-stage hydrotreating reaction is heated by a heating device and then flows into the third-stage hydrotreating reactor R-3. Specifically, the hydrotreating unit 100 includes a first-stage hydrotreating heating furnace F-1. The outflow 15 of the second-stage hydrotreating reaction first passes through the third heat exchanger E-4, and then is heated by the first-stage hydrotreating heating furnace F-1 and flows into the third-stage hydrotreating reactor R-3.

[0076] See Figure 1 , in some embodiments, the outflow 16 of the third-stage hydrotreating reaction is heat-exchanged to 120-250 °C by the fourth heat exchanger E-5 and then enters the first middle-stage separator C-6. In some embodiments, the fourth heat exchanger E-5 is a steam generator (waste heat boiler), and the cold source medium is demineralized water, and the water takes away part of the heat of the outflow 16 of the third-stage hydrotreating reaction.

[0077] Continue to refer to Figure 1 , the hydrotreating unit 100 further includes a fifth heat exchanger E-6, and the fifth heat exchanger E-6 is used for heat exchange between the second heavy component 42 and the outflow 44 of the fifth-stage hydrotreating reaction. In some embodiments, the hydrotreating unit 100 is provided with a second hydrotreating heating furnace F-2. The second heavy component 42 flows through the fifth heat exchanger E-6 and is then heated by the second hydrotreating heating furnace F-2 to 250-380 °C and flows into the fourth-stage hydrotreating reactor R-4.

[0078] The hydrotreating unit 100 further includes a seventh heat exchanger E-8 and an eighth heat exchanger E-9. Among them, the seventh heat exchanger is used for heat exchange between the recycle hydrogen 63 and the first light component 41 and the effluent 44 from the fifth-stage hydrogenation reaction. In some embodiments, the cold source medium of the eighth heat exchanger E-9 is water or air, and water or air takes away most of the heat of the first light component 41 and the effluent 44 from the fifth-stage hydrogenation reaction, cooling the effluent 44 to 30-60°C.

[0079] In some embodiments, the hydrotreating unit 100 is provided with a mixing tank (not shown in the figure), and the reaction raw material 11 first enters the mixing tank for full mixing. In some embodiments, the hydrotreating unit 100 is provided with a filter (not shown in the figure), and after the reaction raw material 11 is fully mixed, it enters the filter to remove solid particles, such as removing solid particles in the reaction raw material 11 larger than 50-200 μm, or removing solid particles larger than 25 μm. Removing the solid particles of the reaction raw material 11 is beneficial to reducing heat exchanger fouling and preventing blockage of the catalyst bed layer at the top of the reactor, as well as improving the heat transfer efficiency of the heat exchanger and extending the operation cycle. In a preferred embodiment, the solid particles in the reaction raw material 11 larger than 50-200 μm are removed first, and then the solid particles larger than 25 μm are removed. The staged filtration helps to protect the precision filter for treating 25 μm at the rear, and at the same time can extend the material blockage time, prevent the filter from being quickly blocked and causing material interruption, and then cause the shutdown of the entire continuous operation device. Setting the filter can remove the solid particles in the reaction raw material 11, which is beneficial to preventing the solid particles from blocking the material channel. Refer to Figure 1 , the hydrotreating unit 100 is provided with a feed buffer tank D-1, and after the reaction raw material 11 enters the feed buffer tank D-1, it is boosted by a feed pump P-1. Preferably, the reaction raw material 11 passes through the mixing tank, the filter, the buffer tank D-1 and the feed pump P-1 in sequence.

[0080] The hydrotreating unit and method of the present disclosure involve a total of five stages of hydrogenation reactions, and the reaction temperature of each stage increases gradually. In the front-end process (the first-stage, second-stage, and third-stage hydrogenation reactions), through the configuration of low-temperature, medium-temperature, and high-airspeed catalysts, not only can the hydrogenation depth and accuracy of light benzene in the reaction raw material be ensured, such as effectively removing sulfur and nitrogen impurities in light benzene, but also the aromatic hydrocarbon loss rate can be effectively reduced in the first-stage hydrotreating.

[0081] Through the mid-section separation process, the effluent from the first-stage hydrotreating can be effectively separated into light and heavy components, achieving two-stage hydrofining. Each reaction stage can be processed according to different feedstock properties to obtain the corresponding best matching effect, thereby ensuring the best selectivity for the conversion of each component in the reaction feedstock into the target product. For example, the effluent after the first-stage hydrotreating includes qualified light benzene. The light benzene in this effluent is separated into light components during the mid-section separation process, avoiding the entry of light benzene (such as benzene and toluene) into the high-temperature second-stage hydrotreating, which is beneficial to reducing the loss of aromatics. At the same time, the second heavy components are subjected to the second-stage hydrotreating, significantly improving the depth and treatment capacity of the second heavy components' hydrogenation.

[0082] Unsaturated olefins, polycyclic unsaturated hydrocarbons, etc. in the reaction feedstock are prone to polymerization and coking at high temperatures, causing coking and carbon deposition of the material and blocking the equipment. Using the hydrotreating method of the present disclosure, in the first-stage hydrotreating, the primary hydrogenation reaction temperature is low, belonging to the liquid-phase pre-hydrogenation process. Unsaturated olefins, polycyclic unsaturated hydrocarbons, etc. that are prone to coking in the reaction feedstock can be hydrogenated and saturated in advance. During the subsequent heating process, the frequency of coking and blocking of the reaction feedstock during the reaction can be greatly reduced, thus solving the problem of easy blockage of equipment in the hydrotreating processes of full-range crude benzene, heavy benzene, coal-based light hydrocarbons, coal tar, etc. during production operation.

[0083] The hydrogenation reaction is an exothermic reaction. The hydrotreating device and method of the present disclosure make full use of the heat of the effluents from the first-stage and second-stage hydrogenation reactions, greatly reducing the energy consumption of the device.

[0084] The hydrotreating device and method of the present disclosure can process reaction feedstocks such as full-range crude benzene components rich in aromatics (for example, light benzene components and heavy benzene components) and coal-based light hydrocarbons, and selectively carry out hydrofining. The light benzene components can be processed into pure benzene, toluene, and xylene, while the heavy benzene components can be hydrofined to obtain high-value-added hydrotreated naphtha and / or diesel blending oil components, and the aromatics loss rate of crude benzene during the processing can be controlled within 1%, or even 0.5%. Compared with the traditional crude benzene hydrogenation process, there is no need to remove heavy benzene, thereby improving the utilization rate of the reaction feedstock, increasing the yield of products, and improving economic benefits.

[0085] In addition, the hydrotreating device and method are suitable for processing a variety of raw materials, and the production device can be adjusted or the raw materials can be replaced online according to production needs, without the need to shut down to replace the catalyst and equipment, nor the need to shut down for device cleaning. This greatly reduces the increase in production costs caused by device startup and shutdown, effectively extends the overall operation cycle of the device, and improves the production efficiency of the enterprise.

[0086] High and low pressure separation

[0087] After the high-low pressure separation of the effluent 44 of the five-stage hydrogenation reaction and the first light component 41, the product stream 47b is obtained. Specifically, the excess hydrogen (recycle hydrogen 63) is separated from the effluent 44 of the five-stage hydrogenation reaction and the first light component 41 through high-pressure separation treatment, and hydrogen sulfide is separated from the effluent after the high-pressure separation treatment through low-pressure separation treatment. The effluent after the low-pressure separation treatment is the product stream 47b. The excess hydrogen can be recycled as recycle hydrogen 63. For example, it can be mixed with the reaction raw materials and used for hydrogenation reaction, etc., and hydrogen sulfide is discharged from the system. The pressure range of the high-pressure separation treatment is 4.0 - 15 Mpa, and the pressure of the low-pressure separation treatment is 0.8 - 2.5 Mpa.

[0088] Continue to refer to Figure 1 , the hydrotreating unit 100 is provided with a high-pressure separator D-2 and a low-pressure separator D-3. The excess hydrogen is separated from the effluent 44 of the five-stage hydrogenation reaction and the first light component 41 through the high-pressure separator D-2. The liquid effluent 46 of the high-pressure separator D-2 enters the low-pressure separator D-3 to separate hydrogen sulfide and obtain the product stream 47b. More specifically, the excess hydrogen (recycle hydrogen 63) separated by the high-pressure separator D-2 is respectively transported to pipelines 61, 64, and 65 through the recycle hydrogen compressor K-1 for recycling.

[0089] Product stream separation

[0090] The effluent after the low-pressure separation treatment (product stream 47b) and the product stream 47a converge to form the product stream 47. The product stream 47 is separated into liquefied gas, refined light aromatics (a mixture containing benzene, toluene, and xylene), hydrotreated naphtha, diesel blending components, etc. through multiple rectification, fractionation, or stripping in the material separation unit 90. Specifically, in some embodiments, the effluent after the low-pressure separation treatment is subjected to the first rectification treatment to obtain a gaseous fraction and a liquid fraction; the gaseous fraction after the first rectification treatment is subjected to the second rectification treatment to obtain liquefied gas; the liquid fraction after the first rectification treatment is subjected to fractionation treatment to obtain refined light aromatics, hydrotreated naphtha, and diesel blending components. In the prior art, the gaseous fraction after the first rectification treatment is mainly butane, pentane, hydrogen sulfide, and a small amount of propane and recycle hydrogen components (methane, hydrogen, etc.). After this fraction is liquefied, propane, butane, and pentane can become liquefied gas. Compared with the prior art, through the second rectification treatment, not only can the hydrogen sulfide dissolved in the liquefied gas be further removed to meet the quality requirements of the liquefied gas, but also this component material can be effectively recovered as a high-value product, improving the total target yield of the reaction raw materials in the processing process, and thus improving the economic benefits of processing production.

[0091] Specifically, in some embodiments, the gaseous fraction at the top of the fractionation process is light aromatic hydrocarbons, the side-stream first-line effluent of the fractionation process becomes hydrotreated naphtha, and the side-stream second-line and / or bottom effluent of the fractionation process becomes diesel blending components. In some embodiments, the side-stream first-line effluent of the fractionation process can be subjected to a third rectification process to obtain hydrotreated naphtha and further separated high-purity refined light aromatic hydrocarbons. Through the third rectification process, the light aromatic hydrocarbons in the hydrotreated naphtha are further separated, which can not only improve the purity of the hydrotreated naphtha to meet its limit requirements for aromatic hydrocarbon content (especially benzene content), but also contribute to increasing the yield of refined light aromatic hydrocarbons. In some embodiments, the side-stream second-line effluent of the fractionation process is subjected to a stripping process to obtain diesel blending components.

[0092] In some embodiments, the material separation unit 90 is provided with a pipeline 48. The bottom effluent remaining after the split flow treatment of the product stream 47 in the material separation unit 90 can flow back to the storage tank D-8 through the pipeline 48, and then be pressurized to 5-15 Mpa by the second booster pump P-3 and flow into the first middle separator C-6.

[0093] In summary, the hydrotreating device and method of the present disclosure can process reaction raw materials widely and flexibly. The reaction raw materials can be one of the whole components of crude benzene, coal-based light hydrocarbons, heavy benzene, and coal tar, or a mixture of several raw materials blended in proportion.

[0094] According to different requirements of the target product, raw materials such as the whole components of crude benzene rich in aromatic hydrocarbons and coal-based light hydrocarbons can be selected for processing. At the same time, when the target products include naphtha, diesel blending components, and low-sulfur and low-nitrogen heavy fuel oil, the reaction raw materials can be adjusted to one or both of heavy benzene and coal tar. Because the conditions of the first-stage hydrogenation reaction are relatively mild, olefins and polycyclic unsaturated hydrocarbons that are prone to polymerization and coking are hydrogenated and saturated in advance, so that it can operate in long cycles under the high-temperature conditions of the second-stage hydrogenation.

[0095] Of course, the hydrotreating device and method of the present disclosure can further process all or several of the above-mentioned raw materials. That is, on the premise of ensuring sufficiently low aromatic hydrocarbon loss and hydrogenation accuracy, qualified aromatic chemical products such as benzene, toluene, and xylene can be produced, and on the premise of effectively reducing device blockage and increasing the production cycle sufficiently, high-value products such as low-sulfur and low-nitrogen hydrotreated naphtha and diesel blending components can be produced simultaneously.

[0096] It should be further noted that in the above-disclosed utility model solution, the term "in sequence" mainly represents the sequence relationship in time or space position, and does not necessarily represent the adjacent relationship in time sequence or the adjacent relationship in space position. For example, between two steps with a sequential order limited by "in sequence", there may be other steps; between two components with a connection relationship limited by "in sequence", there may be other components connected.

[0097] The above are only several embodiments of the present disclosure, and those skilled in the art can make various changes or modifications to the embodiments of the present disclosure without departing from the spirit and scope of the present disclosure based on the content disclosed in the application documents.

Claims

1. A hydroprocessing unit for processing reaction raw materials to obtain hydrogenated products, characterized in that: include: A first stage hydrogenation reaction unit, wherein the first stage hydrogenation reaction unit is used to perform a first hydrogenation refining on the reaction raw materials; a first middle-stage separator, the first middle-stage separator being used to separate the effluent of the first-stage hydrogenation reaction unit into a first light component and a first heavy component; A second middle-section separator, the second middle-section separator is used to separate the first heavy component flowing out of the first middle-section separator to obtain a second light component and a second heavy component; The reaction raw materials include any one, two, three or four of crude benzene fraction, heavy benzene, coal-based light hydrocarbons and coal tar, and the hydrogenation product includes at least a first light component and a second light component.

2. The hydroprocessing device according to claim 1, characterized in that It comprises a product reflux drum, wherein the second light component enters the product reflux drum to separate into a first gaseous substance and a first liquid substance.

3. The hydroprocessing device according to claim 2, characterized in that: A cooler is provided at the gaseous material outlet of the product reflux tank. The first gaseous material flowing out of the product reflux tank is cooled by the cooler to form a second gaseous material and a second liquid material. The second gaseous material is discharged, and the second liquid material flows back to the product reflux tank.

4. The hydroprocessing device according to claim 1, characterized in that: The first middle-section separator is one of a rectifying tower, a stripping tower, a flash tower, and a fractionating tower, and the second middle-section separator is one of a rectifying tower, a fractionating tower, an evaporation tower, and a stripping tower.

5. The hydroprocessing device according to claim 4, characterized in that: The second middle-section separator is a distillation tower, and the second middle-section separator has a first inlet and a second inlet, and the first inlet is arranged higher than the second inlet; A flash tank is provided between the first middle-section separator and the second middle-section separator. The first heavy component is processed by the flash tank to form a gas phase substance and a liquid phase substance. The gas phase substance flowing out of the flash tank enters the first inlet of the second middle-section separator, and the liquid phase substance flowing out of the flash tank enters the second inlet of the second middle-section separator.

6. The hydroprocessing device according to claim 5, characterized in that: A heat exchanger is included. The liquid phase material flowing out of the flash tank exchanges heat with the second heavy component in the heat exchanger before entering the second inlet of the second middle-stage separator.

7. The hydroprocessing device according to any one of claims 1 to 6, characterized in that: It also includes a second stage hydrogenation reaction unit and a booster pump. After the second heavy component is boosted by the booster pump, it enters the second stage hydrogenation reaction unit for further hydrogenation refining and hydrocracking. Wherein, the hydrogenated product also includes the effluent flowing out from the second stage hydrogenation reaction unit.

8. The hydroprocessing device according to claim 7, characterized in that: The first stage hydrogenation reaction unit comprises a primary hydrogenation reactor, a secondary hydrogenation reactor and a tertiary hydrogenation reactor, and the reaction raw materials are sequentially passed through the primary hydrogenation reactor, the secondary hydrogenation reactor and the tertiary hydrogenation reactor; Among them, the first-stage hydrogenation reactor is used to hydrogenate and saturate a part of the easily polymerized substances in the reaction raw materials; the second-stage hydrogenation reactor is used to hydrogenate and saturate further easily polymerized substances in the reaction raw materials and remove part of the sulfur and nitrogen in the reaction raw materials; the third-stage hydrogenation reactor is used to continue to remove the sulfur and nitrogen in the reaction raw materials and to hydrogenate and refine the heavy benzene.

9. The hydroprocessing device according to claim 7, characterized in that: The second stage hydrogenation reaction unit comprises a four-stage hydrogenation reactor and a five-stage hydrogenation reactor, and the second heavy component is pressurized by a booster pump and enters the four-stage hydrogenation reactor and the five-stage hydrogenation reactor in sequence; The fourth-stage hydrogenation reactor is used to deeply hydrogenate and remove sulfur and nitrogen from a part of the second heavy component; the fifth-stage hydrogenation reactor is used to hydrocracking a further part of the second heavy component after passing through the fourth-stage hydrogenation reactor, and to continue to deeply hydrogenate and remove sulfur and nitrogen.

10. The hydroprocessing device according to claim 7, characterized in that: It also includes a high-pressure separator and a low-pressure separator. After the effluent of the first light component and the second-stage hydrogenation reaction unit are combined, they are first passed through the high-pressure separator to remove excess hydrogen, and then passed through the low-pressure separator to remove hydrogen sulfide.

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