Hydrogenation unit and method for producing isooctane from composite oil

Abstract

This application discloses a hydrogenation apparatus and method for producing isooctane from blended oil, belonging to the field of petrochemical technology. The apparatus includes: a catalytic distillation hydrogenation tower, a condenser, a reflux tank, a reboiler, a first compressor, and a hydrogenation reactor. The top of the catalytic distillation hydrogenation tower is connected to the condenser; the condenser is connected to one inlet of the reflux tank; one outlet of the reflux tank is connected to the first compressor; and the other outlet is connected to the catalytic distillation hydrogenation tower. A reboiler is located at the bottom of the catalytic distillation hydrogenation tower; the bottom of the hydrogenation reactor is connected to the catalytic distillation hydrogenation tower. Thus, this application can saturate the olefins in the blended oil, thereby meeting its requirements as a blending component for automotive gasoline and producing isooctane as needed. Furthermore, by separately hydrogenating different components in the blended oil through the catalytic distillation hydrogenation tower and the hydrogenation reactor, equipment and operating costs can be reduced, achieving energy saving and flexible operation.

Description

Technical Field

[0001] This application relates to the field of petrochemical technology, and in particular to a hydrogenation apparatus and method for producing isooctane from composite oil. Background Technology

[0002] Because the olefins in ethanol gasoline contribute to the formation of VOCs (Volatile Organic Compounds) and NO. X As a major source of toxic substances, ethanol gasoline is subject to strict limits on its olefin content, as stipulated in the national standard for automotive gasoline (GB17930-2016). For example, the volume fraction of olefins in 92# gasoline must be ≤18(VIA) / 15(VIB). Blended oil, a component of ethanol gasoline, is primarily composed of olefins. Adding blended oil to ethanol gasoline can cause its olefin content to exceed the standard. Therefore, the blended oil must be hydrogenated to ensure that the olefin content in the ethanol gasoline meets the requirements of the automotive gasoline standard. Summary of the Invention

[0003] This application provides a hydrogenation apparatus and method for producing isooctane from composite oil, which can solve the problem that adding composite oil to ethanol gasoline causes excessive olefin content in the gasoline. The technical solution is as follows:

[0004] In a first aspect, embodiments of this application provide a hydrogenation apparatus for a composite oil capable of producing isooctane, the apparatus comprising: a catalytic distillation hydrogenation tower, a condenser, a reflux tank, a reboiler, a first compressor, and a hydrogenation reactor;

[0005] The top of the catalytic distillation hydrogenation tower is connected to the condenser, the condenser is connected to one inlet of the reflux tank, one outlet of the reflux tank is connected to the first compressor, and the other outlet of the reflux tank is connected to the catalytic distillation hydrogenation tower; the bottom of the catalytic distillation hydrogenation tower is connected to the reboiler; and the bottom of the hydrogenation reactor is connected to the catalytic distillation hydrogenation tower.

[0006] The catalytic distillation hydrogenation tower is used to separate light and heavy components of the composite oil, and to hydrogenate the light components to obtain a first component, a second component, and a first hydrogenation product; the condenser is used to condense and cool the first component, the reflux tank is used to perform gas-liquid separation on the condensed and cooled first component, and the reboiler is used to provide a heat source for the catalytic distillation hydrogenation tower; the first compressor is used to change the pressure of the gaseous product separated by the reflux tank, and the hydrogenation reactor is used to hydrogenate a portion of the material in the second component to obtain a second hydrogenation product.

[0007] Optionally, the apparatus further includes: a first product pump and a first cooler;

[0008] The inlet of the first product pump is connected to the catalytic distillation hydrogenation tower, and the outlet of the first product pump is connected to the first cooler.

[0009] The first product pump is used to change the pressure of the first hydrogenated product exiting the catalytic distillation hydrogenation tower, and the first cooler is used to cool the first hydrogenated product so that the temperature of the first hydrogenated product reaches the required output temperature.

[0010] Optionally, the apparatus further includes: an inlet / outlet heat exchanger, a second cooler, a circulating pump, and a second product pump;

[0011] The feed heat exchanger is connected to the catalytic distillation hydrogenation tower, and the feed heat exchanger is also connected to the second cooler;

[0012] The second cooler is connected to the circulation pump, which in turn is connected to the second product pump, and the circulation pump is connected to the hydrogenation reactor.

[0013] Optionally, the apparatus further includes: a feed pump and a feed heater;

[0014] The inlet of the feed pump is connected to the bottom of the catalytic distillation hydrogenation tower, the outlet of the feed pump is connected to one side of the feed heater, and the other side of the feed heater is connected to the top of the hydrogenation reactor.

[0015] Optionally, the device further includes: a reflux pump;

[0016] The inlet of the reflux pump is connected to the bottom of the reflux tank, and the outlet of the reflux pump is connected to the top of the catalytic distillation hydrogenation tower.

[0017] The reflux pump is used to reflux the liquid phase separated from the reflux tank back to the catalytic distillation hydrogenation tower.

[0018] Optionally, the device further includes: a second compressor;

[0019] The second compressor is connected to the feed heater and is used to change the pressure of hydrogen from the outside.

[0020] Secondly, embodiments of this application provide a method for hydrogenating a composite oil capable of producing isooctane, the method being used in any of the aforementioned apparatuses, the method comprising the following steps:

[0021] The composite oil and the fresh hydrogen from the outside world enter the catalytic distillation hydrogenation tower respectively, where light and heavy components are separated. The light components are then contacted with the hydrogenation catalyst in the catalytic distillation hydrogenation tower to carry out a catalytic hydrogenation reaction, resulting in the first component, the second component, and the first hydrogenation product.

[0022] The first component is condensed and cooled by the condenser and then enters the reflux tank. Gas-liquid separation is performed in the reflux tank. The separated gas phase product is changed by the first compressor and then enters the hydrogenation reactor as circulating hydrogen. The separated liquid phase product is returned to the catalytic distillation hydrogenation tower.

[0023] The second component is divided into three parts in the bottom section of the catalytic distillation hydrogenation tower to obtain a first product, a second product, and a third product. The first product is fed into the catalyst bed of the hydrogenation reactor as quench oil and is used to control the temperature rise of the catalyst bed. The second product is fed into the hydrogenation reactor as feed and mixed with the circulating hydrogen and the fresh hydrogen. The third product is either used as a separate heavy oil product output device or mixed with the first hydrogenation product as a target hydrogenation product output device.

[0024] The second product flows out from the bottom of the catalytic distillation hydrogenation tower, mixes with the recycled hydrogen and fresh hydrogen, and then enters the hydrogenation reactor. In the hydrogenation reactor, it contacts the hydrogenation catalyst to carry out a catalytic hydrogenation reaction and obtain the second hydrogenation product.

[0025] The second hydrogenation product enters the catalytic distillation hydrogenation tower from the bottom of the hydrogenation reactor. The hydrogen carried in the second hydrogenation product is separated by the catalytic distillation hydrogenation tower and used to replenish the hydrogen required for the hydrogenation reaction in the catalytic distillation hydrogenation tower.

[0026] Optionally, the molar ratio of hydrogen required in the catalytic distillation hydrogenation tower to isooctene in the composite oil is 1.5 to 3:1.

[0027] Optionally, the mass ratio of the first product to the third product is 1 to 3:1;

[0028] The mass ratio of the second product to the third product is 2 to 3:1.

[0029] Optionally, after the second product flows out from the bottom of the catalytic distillation hydrogenation tower, it is mixed with the recycled hydrogen and fresh hydrogen and then enters the hydrogenation reactor. In the hydrogenation reactor, it contacts the hydrogenation catalyst to carry out a catalytic hydrogenation reaction to obtain the second hydrogenation product. The reaction is carried out under the following operating conditions: reaction temperature 200-350°C, reaction pressure 2.0-5.0 MPa.

[0030] The technical solution provided in this application can bring at least the following beneficial effects:

[0031] The composite oil hydrogenation apparatus for producing isooctane provided in this application embodiment separates the light and heavy components of the composite oil through a catalytic distillation hydrogenation tower, and then hydrogenates the separated light components. Both distillation and hydrogenation are carried out in a single catalytic distillation hydrogenation tower, simplifying the process and saving investment costs. A reboiler provides a heat source to the catalytic distillation hydrogenation tower, ensuring thorough separation of light and heavy components and hydrogenation of the light components within the tower. A condenser cools the first component distilled from the composite oil, making it a gas-liquid coexisting component. A reflux tank separates the first component into gaseous and liquid products. A first compressor pressurizes the gaseous product, which is then fed into the hydrogenation reactor. The gaseous product entering the reactor increases the hydrogen partial pressure and absorbs some of the reaction heat.

[0032] Because the catalytic distillation hydrogenation tower primarily hydrogenates the lighter components such as C8 with smaller molecular weights in the composite oil, the reaction temperature and pressure are relatively low. Meanwhile, the hydrogenation reactor focuses on hydrogenating the larger C8 molecules in the composite oil. 12 C 16 Hydrogenation of heavy components requires higher reaction temperatures and pressures. This method of selecting different reaction pressures and temperatures based on different hydrogenation materials helps reduce equipment and operating costs. Furthermore, light components such as C8 can be discharged as isooctane after hydrogenation, while the C8 content in the composite oil... 12 C 16 Since the content of heavy components is less than 20% (by mass), when hydrogenating the heavy components as the second product, it is not necessary to excessively pursue extremely high hydrogenation reaction conversion rates to ensure that the target hydrogenation product meets the requirements of relevant standards. This can greatly reduce the utility and energy consumption required for hydrogenation operations.

[0033] The target hydrogenation product obtained by the isooctane-producing hydrotreating unit provided in this application has low saturated vapor pressure, high octane number, no or low sulfur content, and low olefin content, making it a high-quality clean gasoline blending component. Furthermore, compared to conventional processes, it eliminates the need for equipment such as reaction product coolers, high-pressure separators, product stripping towers, and associated overhead reflux and bottom reboiling systems, thus reducing equipment investment. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of a composite oil hydrogenation device capable of producing isooctane, provided in an embodiment of this application.

[0035] Figure 2 This is a schematic diagram of the structure of a second composite oil hydrogenation device capable of producing isooctane, provided in the embodiments of this application;

[0036] Figure 3 This is a flowchart of a method for hydrogenating composite oil provided in an embodiment of this application.

[0037] Figure label:

[0038] 1-Catalytic distillation hydrogenation tower; 2-Condenser; 3-Reflux tank; 4-Reboiler; 5-First compressor; 6-Hydrogenation reactor; 7-First product pump; 8-First cooler; 9-Inlet / outlet heat exchanger; 10-Second cooler; 11-Circulation pump; 12-Second product pump; 13-Feed pump; 14-Feed heater; 15-Reflux pump; 16-Second compressor. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0040] With the orderly expansion of the use of ethanol gasoline in vehicles, the future of MTBE (methyl tert-butyl ether) has become the focus of industry attention, and has also brought unprecedented challenges to the C4 deep processing industry, which had entered a period of stable development.

[0041] After MTBE production ceased, isobutylene could still be used as a raw material for chemical production. However, domestically produced chemical products using isobutylene as a raw material generally suffer from problems such as a limited number of product grades, weak new product development capabilities, and high production costs. Furthermore, the market capacity for chemical products is limited, making it impossible to find a market for tens of millions of tons of isobutylene. In contrast, the process of producing blended gasoline using mixed C4 as a raw material can not only produce more high-octane gasoline blending components but also solve the problem of isobutylene market demand.

[0042] The main reaction in the process of producing composite oil from mixed C4 olefins is the dimerization of isobutylene (IB) to generate isomers of trimethylpentene, such as 2,4,4-trimethylpentene (a C8 olefin, i.e., DIB). The reaction formula is as follows:

[0043] IB+IB→DIB (1)

[0044] Side reactions include the reaction of IB with DIB to form a trimer (C 12 Olefins (i.e., TIB) and IB react with TIB to form tetramers (C) 16 Alkenes (TEBs) have the following reaction formula:

[0045] IB+DIB→TIB (2)

[0046] IB+TIB→TEB (3)

[0047] The resulting composite oil contains 82-90% C8 olefins. 12 The olefin content is 5-15%, C 16 The olefin content ranges from 0.01% to 1.5%. Therefore, the olefin content in the composite oil is almost 100%, with the main component being C8 olefins, namely isooctene, followed by C... 12 Alkenes, and a very small amount of C. 16 Olefins. Because olefins in ethanol gasoline contribute to the formation of VOCs and NO. X And the main source of toxic substances. Among them, NO... X Hydrocarbons (HC) readily generate photochemical smog, which permeates the troposphere, under the influence of sunlight. This photochemical smog contains up to 90% ozone, which can damage the human respiratory system and cause diseases such as bronchitis and pneumonia. Furthermore, NO... X This is also one of the causes of acid rain. Therefore, the standard for automotive gasoline (GB 17930-2016) imposes strict limits on the olefin content in ethanol gasoline, such as requiring that the volume fraction of olefins in 92# gasoline be ≤18(VIA) / 15(VIB). Therefore, when the addition of blended oil as a component of ethanol gasoline causes the olefin content in ethanol gasoline to exceed the standard, the blended oil must be hydrogenated to obtain isooctane oil, a high-quality clean gasoline blending component with low saturated vapor pressure, high octane number, no sulfur, no benzene, no aromatics, and no or low olefin content.

[0048] CN1160701A describes a method for hydrogenating C3 fractions, but the purpose of this method is to hydrogenate the alkynes in the C3 fractions, rather than to hydrogenate and saturate the composite oil produced by isobutylene oligomerization with an olefin content close to 100%.

[0049] CN101081998A describes a method for hydrogenating C4 fraction. The raw material C4 fraction is mixed with hydrogen and then fed into a hydrogenation reactor. It first contacts hydrogenation catalyst I to carry out a diene hydrogenation saturation reaction. The reaction product is directly contacted with hydrogenation catalyst II without separation to carry out impurity removal and olefin hydrogenation saturation reaction. The obtained C4 fraction product can be used as a high-quality feedstock for steam cracking to produce ethylene, and can also be used as liquefied petroleum gas for vehicles.

[0050] CN101113126A describes a method for catalytic hydrogenation of olefin-containing light hydrocarbons. This method uses industrial or domestic olefin-containing liquefied petroleum gas (LPG) or light oil as feedstock. Catalytic hydrogenation saturates the olefins in the feedstock, producing saturated LPG or light oil that meets the required standards. However, for feedstocks with high olefin content, this patent uses a tubular reactor for olefin hydrogenation saturation. Tubular reactors have drawbacks such as complex structure and difficult maintenance. Furthermore, the hydrogenation products are separated by only one gas-liquid separator. The liquid separated at the bottom of the gas-liquid separator, when used as a product, may contain dissolved or entrained light components such as hydrogen and hydrogen sulfide.

[0051] CN107827694A discloses an apparatus and method for producing isooctane using indirect alkylation technology. The method involves feeding a composite oil into a desulfurization tower, then introducing hydrogen gas into the tower through inlet IV. Inside the tower, the composite oil and hydrogen gas are mixed and subjected to a hydrodesulfurization reaction. Hydrogenation and desulfurization occur in the same tower. The bottom product of the desulfurization tower is high-octane alkylated oil—isooctane, which can be used as a gasoline blending component. The top product is a mixture of residual hydrogen gas and generated hydrogen sulfide, which can be sent to a flare system for utilization. However, this method does not mention the feed location of the composite oil, the type of catalyst, the catalyst loading amount, or how to control the reaction temperature rise. It also does not mention the number of trays in the desulfurization tower, or the operating temperatures and pressures at the top and bottom of the tower. Furthermore, it does not specify the type and nature of sulfur in the composite oil, nor does it mention the heating method at the bottom of the desulfurization tower.

[0052] Therefore, it is necessary to provide a highly operable, flexible, and low-cost method and apparatus for hydrogenating blended oils, which hydrogenates and saturates the olefins in the blended oils, thereby reducing the olefin content in the blended oils and consequently reducing the olefin content in ethanol gasoline.

[0053] Before providing a detailed explanation of the embodiments of this application, the principles involved in the embodiments of this application will be explained first.

[0054] When C4 produced from an FCC (Fluid Catalytic Cracking) unit is used as feedstock for an isobutylene cyclohexane unit, the composition and boiling points of the resulting cyclohexane oil are shown in Table 1. In addition, the C4 feedstock contains trace amounts of sulfides, such as dimethyl disulfide, ethylmethyl disulfide, and diethyl disulfide. These sulfides concentrate in the cyclohexane oil during production, resulting in a sulfide content typically between 5 and 50 mg / kg. These sulfides can be converted to H2S through hydrogenation of the cyclohexane oil. The H2S then exits the top of the catalytic distillation hydrogenation tower with circulating hydrogen gas. H2S can be removed by installing a circulating hydrogen desulfurization tower or by emitting purge gas.

[0055] Table 1. Components and Boiling Points of Composite Oil

[0056] Components mass fraction / % Boiling point at normal pressure / °C <![CDATA[C8 olefins]]> 82～95 99～102 <![CDATA[C 12 Olefins 5～15 175～185 <![CDATA[C 16 Olefins 0.01～1.5 230～250

[0057] As can be seen from Table 1, the C8 olefin content in the composite oil is over 82%, and its operating conditions, such as hydrogenation saturation reaction temperature, reaction pressure, and hydrogen-to-oil ratio, are better than those of the C8 olefins. 12 Olefins and C 16 Olefin mildening can be achieved by hydrogenating the C8 olefins in the composite oil within a catalytic distillation hydrogenation tower, and then hydrogenating the C8 olefins in the composite oil within a hydrogenation reactor. 12 Olefins, C 16 A new method for hydrogenating and saturating olefins, thereby reducing equipment and operating costs. 12 Olefins, C 16 The degree of olefin hydrogenation saturation can be controlled by the reactor feed flow rate and quench oil flow rate. Furthermore, depending on the actual situation, the hydrogenated C8 alkanes can be used as isooctane as the output product.

[0058] Figure 1 This application provides an embodiment of a hydrotreating unit for producing isooctane from a composite oil. See also: Figure 1 The device includes: a catalytic distillation hydrogenation tower 1, a condenser 2, a reflux tank 3, a reboiler 4, a first compressor 5, and a hydrogenation reactor 6;

[0059] The top of the catalytic distillation hydrogenation tower 1 is connected to the condenser 2. The condenser 2 is connected to one inlet of the reflux tank 3. One outlet of the reflux tank 3 is connected to the first compressor 5. The other outlet of the reflux tank 3 is connected to the catalytic distillation hydrogenation tower 1. A reboiler 4 is provided at the bottom of the catalytic distillation hydrogenation tower 1. The bottom of the hydrogenation reactor 6 is connected to the catalytic distillation hydrogenation tower 1.

[0060] Catalytic distillation hydrogenation tower 1 is used to separate light and heavy components of the composite oil, and to hydrogenate the light component to obtain a first component, a second component, and a first hydrogenation product; condenser 2 is used to condense and cool the first component; reflux tank 3 is used to perform gas-liquid separation on the condensed and cooled first component; reboiler 4 is used to provide a heat source for catalytic distillation hydrogenation tower 1; first compressor 5 is used to change the pressure of the gaseous product separated from reflux tank 3; hydrogenation reactor 6 is used to hydrogenate a portion of the material in the second component to obtain a second hydrogenation product.

[0061] The composite oil hydrogenation apparatus for producing isooctane provided in this application embodiment mainly separates the light and heavy components of the composite oil through a catalytic distillation hydrogenation tower, and then hydrogenates the separated light components. The separation of light and heavy components and the hydrogenation reaction are all carried out in a single catalytic distillation hydrogenation tower, which simplifies the process and saves investment costs. A reboiler provides a heat source to the catalytic distillation hydrogenation tower, allowing the composite oil to fully separate the light and heavy components and undergo hydrogenation of the light components within the tower. A condenser cools the first component distilled from the composite oil, making it a gas-liquid coexisting component. A reflux tank separates the first component into gas and liquid phases, separating them into a single gaseous product and a liquid product. A first compressor pressurizes the gaseous product, which is then fed into a hydrogenation reactor. The gaseous product entering the reactor increases the hydrogen partial pressure and absorbs some of the reaction heat. The second product in the second component is hydrogenated in the hydrogenation reactor.

[0062] Because the catalytic distillation hydrogenation tower mainly hydrogenates the lighter components such as C8 with smaller molecular weights in the composite oil, the reaction temperature and pressure are relatively low. Meanwhile, the hydrogenation reactor is used to hydrogenate the larger C8 molecules in the composite oil. 12 C 16 Hydrogenation of heavy components requires higher reaction temperatures and pressures. This method of selecting different reaction pressures and temperatures based on different hydrogenation materials helps reduce equipment and operating costs. Furthermore, light components such as C8 can be discharged as isooctane after hydrogenation, while the C8 content in the composite oil... 12 C 16 Since the content of heavy components is less than 20% (by mass), when hydrogenating heavy components, it is not necessary to excessively pursue extremely high hydrogenation reaction conversion rates to ensure that the target hydrogenation product meets the requirements of relevant standards, which can greatly reduce the utility consumption and energy consumption required for hydrogenation operations.

[0063] The target hydrogenation product obtained by the isooctane-producing hydrotreating unit of the composite oil provided in this application has low saturated vapor pressure, high octane number, no or low sulfur content, and low olefin content, making it a high-quality clean gasoline blending component. Furthermore, compared to conventional processes, it eliminates the need for equipment such as reaction product coolers, high-pressure separators, product stripping towers, and associated overhead reflux and bottom reboiling systems, reducing equipment investment and operating costs.

[0064] Furthermore, the apparatus provided in this application embodiment can also produce the first hydrogenation product, namely isooctane, as needed; the first hydrogenation product can also be directly mixed with the third product, and the mixed product can be used as a high-quality gasoline blending component to be added to the gasoline pool of the entire plant.

[0065] It should be noted that the catalytic distillation hydrogenation tower 1 includes a rectifying section, a reaction section, and a stripping section connected sequentially from top to bottom. The rectifying section is used to separate the first component and the heavy components carried in the first hydrogenation product. The separated first component flows out from the top of the catalytic distillation hydrogenation tower 1, and the separated first hydrogenation product is drawn off from the side stream of the catalytic distillation hydrogenation tower 1. The reaction section is used to hydrogenate the light components in the composite oil to obtain the first hydrogenation product. The stripping section is used to separate the light components and hydrogen from the heavy components in the composite oil. The separated light components and hydrogen flow into the reaction section for hydrogenation, and the separated heavy components flow out from the bottom of the catalytic distillation hydrogenation tower 1 into the hydrogenation reactor 6. The top temperature of the catalytic distillation hydrogenation tower 1 is 100–185℃, the bottom temperature is 250–350℃, and the operating pressure is 0.1–0.5 MPa. For example, the top temperature of the catalytic distillation hydrogenation column 1 can be 100°C, 125°C, 150°C, or 185°C, etc., and the bottom temperature can be 250°C, 300°C, or 350°C, etc., and the operating pressure can be 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, or 0.5 MPa, etc. Furthermore, the liquid hourly space velocity (LHSV) of the catalyst bed within the catalytic distillation hydrogenation column 1 is 1.0–6.0 h⁻¹. -1 For example, the liquid hourly space velocity (LHSV) can be 1.0 h⁻¹. -1 2.0h -1 3.0h -1 4.0h -1 5.0h -1 Or 6.0h -1 wait.

[0066] It should be noted that the first hydrogenation product is the C8 alkane obtained by hydrogenating and saturating C8 olefins in the composite oil, and the second hydrogenation product is the C8 alkane obtained by hydrogenating C8 olefins in the composite oil. 12 Olefins and C 16 C60 obtained by hydrogenation saturation of olefins 12 Alkanes and C 16 Alkanes.

[0067] It is worth noting that the catalyst bed in the catalytic distillation hydrogenation tower 1 can contain a support and a metal component supported on the support. The support can be one or more of alumina, silica, diatomaceous earth molecular sieves, etc., and the metal component can be a noble metal component with high activity and mild operating conditions, such as palladium or platinum; or a non-noble metal component with lower activity, higher reaction temperature and pressure but strong anti-fouling ability, such as nickel, molybdenum, cobalt, etc.

[0068] It should be noted that setting up a catalytic distillation hydrogenation tower 1 has two main advantages: First, both distillation and hydrogenation processes can be completed within the tower, simplifying the process flow and saving investment costs. Second, the presence of temperature and concentration differences within the tower allows for the placement of different types of catalysts at different locations, enabling various catalytic reactions to be carried out, thus allowing several reactions to be completed within a single tower. For example, noble metal catalysts and non-noble metal catalysts can be placed at different locations within the reaction section of the tower. Since non-noble metal catalysts have a higher tolerance for sulfur-containing compounds compared to noble metal catalysts, they can be used for desulfurization reactions, while noble metal catalysts can be used for olefin hydrogenation saturation reactions. Furthermore, utilizing the temperature gradient within the tower can improve the conversion rate of the main reaction and reduce the conversion rate of side reactions.

[0069] It should be noted that the condenser 2 is used to condense and cool the first component, thereby reducing the temperature of the first component and causing the small molecule hydrocarbons contained in the first component to change from the gas phase to the liquid phase. The reflux tank 3 is used to separate the first component after condensation and cooling, so that the separated gas phase product is used as circulating hydrogen for the subsequent hydrogenation reaction of the second component, and the separated liquid phase product is returned to the catalytic distillation hydrogenation tower 1 for further rectification. This can reduce energy waste. The reboiler 4 is used to provide a heat source for the catalytic distillation hydrogenation tower 1 to ensure that the temperature inside the catalytic distillation hydrogenation tower 1 reaches the required temperature.

[0070] It should be noted that the first compressor 5 is used to change the pressure of the gaseous product separated from the reflux tank 3 and used as circulating hydrogen, so that the pressure of the gaseous product reaches the pressure required for the hydrogenation reaction in the hydrogenation reactor 6, thereby increasing the hydrogen partial pressure in the hydrogenation reactor 6.

[0071] It should be noted that the hydrogenation reactor 6 is used to hydrogenate the second product in the second component to obtain the hydrogenated product. The type of hydrogenation reactor 6 can be preset according to the usage requirements. For example, the hydrogenation reactor 6 can be an adiabatic bubbling bed reactor and / or a trickle bed reactor. Preferably, the hydrogenation reactor 6 can be a trickle bed reactor. The hydrogenation reactor 6 can be provided with at least two catalyst bed sections. For example, the hydrogenation reactor 6 can be provided with two or three catalyst bed sections. The hydrogenation reactor 6 can also be one or at least two reactors connected in series. For example, the hydrogenation reactor 6 can be used alone, or two or three reactors can be used in series. Preferably, the hydrogenation reactor 6 can be a single reactor with two catalyst bed sections.

[0072] It should be noted that the inlet temperature of hydrogenation reactor 6 is 200–350℃, the inlet pressure is 2.0–5.0 MPa, and the liquid hourly space velocity is 0.5–5.0 h⁻¹. -1 The hydrogen-to-oil ratio is 250–800 Nm. 3 / m 3 The bed temperature rise is 15–35°C. For example, the inlet temperature can be 200°C, 250°C, 300°C, or 350°C, the inlet pressure can be 2.0 MPa, 3.0 MPa, 4.0 MPa, or 5.0 MPa, and the liquid hourly space velocity (LHSV) is 0.5 h⁻¹. -1 1.5h -1 2.5h -1 3.5h -1 4.5h -1 Or 5.0h -1 The hydrogen-to-oil ratio is 250 Nm. 3 / m 3 350Nm 3 / m 3 450Nm 3 / m 3 550Nm 3 / m 3 650Nm 3 / m 3 750Nm 3 / m 3 Or 800Nm 3 / m 3 The bed temperature rise can be 15℃, 25℃ or 35℃, etc.

[0073] It is worth noting that the catalyst bed in the hydrogenation reactor 6 can contain a support and a metal component supported on the support. The support can be one or more of alumina, silica, diatomaceous earth molecular sieves, etc., and the metal component can be a bimetallic component with low activity, high reaction temperature and pressure but strong anti-fouling ability, such as nickel / molybdenum, nickel / cobalt, etc.

[0074] For example, the catalytic distillation hydrogenation tower 1 has five feed streams, from top to bottom: reflux liquid from reflux tank 3, composite oil from isobutylene composite unit, fresh hydrogen from the outside, second hydrogenation product from hydrogenation reactor 6, and gas-liquid two-phase mixture from reboiler 4; the catalytic distillation hydrogenation tower 1 also has four discharge streams, from top to bottom: the first component collected from the top of the catalytic distillation hydrogenation tower 1, the first hydrogenation product extracted from the side stream of the catalytic distillation hydrogenation tower 1, the second component from the bottom of the catalytic distillation hydrogenation tower 1, and the feed from reboiler 4.

[0075] It should be noted that the gas-liquid two-phase mixture from reboiler 4 is hydrogen and C. 12 Olefins, C 16 Olefins, C 12 Alkanes and C 16 A mixture of alkanes.

[0076] It is worth noting that the five feed streams enter the catalytic distillation hydrogenation tower 1 at the following locations: the reflux liquid can enter from the top tray of the catalytic distillation hydrogenation tower 1, i.e., the first tray (counting from top to bottom); the mixed oil can enter below the reaction section, at a distance of 3 to 6 trays from the bottom of the reaction section; the top of the reaction section is located below the first hydrogenation product outlet and at a distance of 1 to 3 trays from the first hydrogenation product outlet; the fresh hydrogen can enter below the mixed oil inlet and at a distance of 4 to 8 trays from the mixed oil inlet; the second hydrogenation product can enter below the fresh hydrogen inlet, at a distance of 4 to 8 trays from the fresh hydrogen inlet, and above the bottom tray, at a distance of 6 to 10 trays from the bottom tray; the gas-liquid two-phase mixture from the reboiler 4 can enter from the gas phase space below the bottom tray.

[0077] It is worth noting that the extraction locations of these four outputs are as follows: the first component can be extracted from the top of the catalytic distillation hydrogenation tower 1; the first hydrogenation product can be extracted from below tray 1 in the catalytic distillation hydrogenation tower 1, at a distance of 4 to 8 trays from tray 1; the second component of the catalytic distillation hydrogenation tower 1 can be extracted from the bottom of the tower bottom; and the feed to the reboiler 4 can be extracted from the bottom of the tower bottom of the catalytic distillation hydrogenation tower 1.

[0078] It should be noted that the main component of the composite oil from the isobutylene composite unit is C8 olefins, with a mass content of 82-95%, and it also contains 5-15% C. 12 Olefins and 0.01–1.5% C 16Olefins are present in the composite oil, which contains almost 100% olefins. The new hydrogen can be high-purity hydrogen with a purity greater than 99.9% (by volume), such as hydrogen purified by pressure swing adsorption, or industrial hydrogen with lower hydrogen content, such as reformed hydrogen. However, to reduce equipment and operating costs, hydrogen with a purity greater than 85% (by volume) should be preferred. The main component of the second hydrogenation product from hydrogenation reactor 6 is C. 12 Alkanes, C 16 Alkanes, hydrogen and small amounts of C 12 Olefins, C 16 Olefins and small molecule hydrocarbons produced by cracking, etc.

[0079] When these five materials enter the catalytic distillation hydrogenation tower 1 at their respective entry points, under the action of fractionation, C in the second hydrogenation product... 12 Alkanes, C 16 Alkanes and small amounts of C 12 Olefins, C 16 Olefins flow to the bottom of catalytic distillation hydrogenation tower 1. After the light components such as hydrogen are separated in the bottom section of catalytic distillation hydrogenation tower 1, part of it is used as feed to reboiler 4, and the other part is the second component. The second component is further divided into three parts: the first product, the second product, and the third product, which are respectively the quench oil of hydrogenation reactor 6, the feed to hydrogenation reactor 6, and the heavy oil product. Meanwhile, C8 olefins, hydrogen, and a small amount of small molecule hydrocarbons produced by cracking in catalytic distillation hydrogenation tower 1 flow to the upper part of catalytic distillation hydrogenation tower 1. When they flow to the catalyst bed in the reaction section, under the action of the hydrogenation catalyst, C8 olefins react with H2 to produce C8 alkanes. The generated C8 alkanes, hydrogen, and a small amount of small-molecule hydrocarbons produced by cracking leave the reaction section and continue flowing to the upper part of the catalytic distillation hydrogenation tower 1. After leaving the top of the tower and being condensed and cooled by condenser 2, the gas enters reflux tank 3 for gas-liquid separation. The gaseous phase is used as circulating hydrogen and enters the first compressor 5, while the liquid phase is entirely returned to the catalytic distillation hydrogenation tower 1 as reflux. To prevent the accumulation of inert gases and H2S in the hydrogen circulating stream, some gas can be discharged as purge gas (waste hydrogen) to other devices for further treatment before entering the first compressor 5. For example, it can be discharged to a pressure swing adsorption (PSA) unit as a feedstock for hydrogen purification.

[0080] The second product from the second component in the bottom of the catalytic distillation hydrogenation tower 1 is mixed with the gaseous product, i.e., recycled hydrogen, from the first compressor 5. The mixture is heated and then enters the hydrogenation reactor 6. In the hydrogenation reactor 6, the C in the second product... 12 Olefins, C 16 Olefins and H2 come into contact with a hydrogenation catalyst to undergo a catalytic hydrogenation reaction, causing C... 12 Olefins, C 16Olefins are saturated, and sulfides such as dimethyl disulfide are converted to H2S. The H2S then exits the top of the catalytic distillation hydrogenation column 1 along with the gaseous products. H2S is removed by either setting up a circulating hydrogen desulfurization column or by releasing purge gas. Ultimately, the C8 olefin conversion rate is ≥99%, and the C8 olefin conversion rate is ≥99%. 12 Total olefin conversion ≥65%, C 16 Total olefin conversion rate ≥ 65%.

[0081] It is worth noting that the third product refers to the C2 produced after the second component has been hydrogenated to saturation in the hydrogenation reactor 6 and finally separated into light components such as H2 in the catalytic distillation hydrogenation tower 1. 12 Olefins, C 12 Alkanes, C 16 Olefins, C 16 The olefin content of the mixture obtained by mixing alkanes with the heavy components of the blended oil after light and heavy component separation in catalytic distillation hydrogenation tower 1 is determined by the feed flow rate and quench oil flow rate of hydrogenation reactor 6. When the feed flow rate (second product flow rate) and quench oil flow rate (first product flow rate) of hydrogenation reactor 6 increase, the olefin content in the third product or heavy oil product decreases, and vice versa. Generally, the olefin content accounts for 15-25% of the total third product or heavy oil product; for example, it can be 15%, 20%, or 25%, and the maximum is no more than 35%. This portion of heavy oil product accounts for only 5.0-16.5% of the blended oil; for example, it can be 5.0%, 7.5%, 10.0%, 12.5%, or 16.5%. Since the mass or volumetric flow rate of this third product or heavy oil product is very small, generally less than 2% of the total volume of the refinery's gasoline pool, when it is mixed with other gasoline blending components in the refinery's gasoline pool, such as isooctane obtained through this unit, which is the first hydrogenation product, it can easily meet the requirements of automotive gasoline standards such as GB 17930-2016 olefin volume fraction ≤15%.

[0082] Optionally, see Figure 2 The device also includes a first product pump 7 and a first cooler 8; the inlet of the first product pump 7 is connected to the catalytic distillation hydrogenation tower 1, and the outlet is connected to the first cooler 8.

[0083] It should be noted that the first product pump 7 is used to increase the pressure of the first hydrogenated product drawn from the side stream of the catalytic distillation hydrogenation tower 1, so that the pressure of the first hydrogenated product reaches the required output pressure, and the first cooler 8 is used to cool the first hydrogenated product, so that the temperature of the first hydrogenated product reaches the required output temperature.

[0084] For example, after hydrogenation in catalytic distillation hydrogenation tower 1, almost all C8 olefins in the blended oil are converted into the first hydrogenation product, namely C8 alkanes. This portion of C8 alkanes is isooctane, whose main component is 2,4,4-trimethylpentane. It can be used as a high-quality gasoline blending component output or sold as isooctane product or semi-finished product. To minimize the presence of dissolved hydrogen, small-molecule hydrocarbons, and harmful impurities such as H2S in the first hydrogenation product (isooctane) within catalytic distillation hydrogenation tower 1, and to ensure that the product passes flash point and silver corrosion tests, the first hydrogenation product can be collected from the corresponding position between trays 4 and 8 below tray 1 of catalytic distillation hydrogenation tower 1. The first hydrogenation product collected via the side stream is pressurized by the first product pump 7 and cooled to approximately 40°C by the first cooler 8. It can then be output separately or mixed with the third product before being output.

[0085] Optionally, see [link to relevant documentation] Figure 2 The device also includes: a feed heat exchanger 9, a second cooler 10, a circulation pump 11, and a second product pump 12; the feed heat exchanger 9 is connected to the catalytic distillation hydrogenation tower 1, and the feed heat exchanger 9 is also connected to the second cooler 10; the second cooler 10 is connected to the circulation pump 11, and the second cooler 10 is also connected to the second product pump 12, and the circulation pump 11 is connected to the hydrogenation reactor 6.

[0086] It should be noted that the feed heat exchanger 9 is used to exchange heat between the composite oil from the isobutylene composite unit and the hydrogenation product at the bottom of the catalytic distillation hydrogenation tower 1, thereby reducing the temperature of the hydrogenation product and increasing the temperature of the composite oil. This reduces the heat load on the second cooler 10 and the reboiler 4 in the catalytic distillation hydrogenation tower 1, thus achieving energy saving.

[0087] It should be noted that the second cooler 10 is used to cool the first and third products at the bottom of the catalytic distillation hydrogenation tower 1, the circulating pump 11 is used to pressurize the cooled first product to reach the pressure required by the hydrogenation reactor 6, and the second product pump 12 is used to pressurize the cooled third product to reach the product output pressure.

[0088] For example, the first and third products from the bottom of the catalytic distillation hydrogenation tower 1 are cooled to 40°C by the second cooler 10 after exchanging heat with the blended oil in the feed heat exchanger 9. Then they are separated. The first product is pressurized to the required pressure of the hydrogenation reactor 6 by the circulating pump 11 and sent as quench oil to the space between two adjacent catalyst beds in the hydrogenation reactor. The third product is pressurized to the required external pressure by the second product pump 12 and is either discharged separately or mixed with the first hydrogenation product before being discharged.

[0089] It is worth noting that the first product, quench oil, serves two purposes. First, since the olefin hydrogenation saturation reaction is exothermic, 1 mol of olefin saturation releases approximately 30 kcal of heat. Without intervention, this heat will cause the reaction temperature to rise, which in turn will accelerate the olefin saturation and polymerization reactions, leading to a rapid increase in temperature. This, in turn, will reduce catalyst life and result in substandard product quality. Therefore, measures must be taken to limit the temperature rise of the catalyst bed. Injecting quench oil between adjacent catalyst bed layers allows it to heat up or vaporize within the hydrogenation reactor 6, thus absorbing the heat and controlling the reaction temperature. Second, the hydrogenation product, quench oil, still contains a certain amount of olefins. This portion of quench oil is recycled back to the hydrogenation reactor 6, where it can continue the hydrogenation saturation reaction, further reducing the olefin content of the second hydrogenation product.

[0090] Optionally, see Figure 2 The device also includes a feed pump 13 and a feed heater 14; the inlet of the feed pump 13 is connected to the bottom of the catalytic distillation hydrogenation tower 1, the outlet of the feed pump 13 is connected to one side of the feed heater 14, and the other side of the feed heater 14 is connected to the top of the hydrogenation reactor 6.

[0091] It should be noted that the feed pump 13 is used to pressurize the second product in the bottom of the catalytic distillation hydrogenation tower 1 to reach the pressure required by the hydrogenation reactor 6.

[0092] It should be noted that the feed heater 14 is used to heat the second product after it has been pressurized by the feed pump 13, so that its temperature reaches the required reaction temperature of 200-300°C. For example, the heating temperature can be 200°C, 250°C, or 300°C. The type of feed heater 14 can be preset according to usage requirements; for example, the feed heater 14 can be selected as a shell-and-tube heat exchanger, an electric heater, or a furnace, depending on the actual situation. When a shell-and-tube heat exchanger is used, its heating medium can be high-pressure steam, heat transfer oil, or a high-temperature process medium.

[0093] Optionally, see Figure 2 The device also includes a reflux pump 15; the inlet of the reflux pump 15 is connected to the bottom of the reflux tank 3, and the outlet is connected to the top of the catalytic distillation hydrogenation tower 1.

[0094] It should be noted that the reflux pump 15 is used to provide a certain pressure to the liquid phase separated from the reflux tank 3, so that it is refluxed back to the catalytic distillation hydrogenation tower 1.

[0095] Optionally, see Figure 2 The device also includes a second compressor 16.

[0096] It should be noted that the second compressor 16 is connected to the feed heater 14, and the second compressor 16 is used to change the pressure of the new hydrogen from the outside of the device.

[0097] It should be noted that the second compressor 16 may or may not be installed depending on the actual operation of the unit. When the pressure of the new hydrogen from the outside or the system is greater than the pressure required by the composite oil hydrogenation unit, the second compressor 16 may not be installed; otherwise, the second compressor 16 must be installed.

[0098] Figure 3 This is a flowchart of a method for hydrogenating composite oil provided in an embodiment of this application. This method is used in the above-mentioned... Figures 1-2 The apparatus shown. See also Figure 3 The method includes:

[0099] Step 301: The composite oil and the new hydrogen from the outside world enter the catalytic distillation hydrogenation tower 1 respectively, and the light components and heavy components are separated in the catalytic distillation hydrogenation tower 1. The light components are contacted with the hydrogenation catalyst in the catalytic distillation hydrogenation tower 1 to carry out the catalytic hydrogenation reaction, and the first component, the second component and the first hydrogenation product are obtained in the catalytic distillation hydrogenation tower 1.

[0100] It should be noted that the molar ratio of hydrogen to isooctene in the composite oil required in the catalytic distillation hydrogenation tower 1 is 1.5–3:1. For example, this ratio can be 1.5:1, 1.7:1, or 3:1, etc. The hydrogen mainly consists of two parts: recycled hydrogen from the hydrogenation reactor 6 and fresh hydrogen from the outside. The main function of the recycled hydrogen is to maintain the hydrogen partial pressure required for the hydrogenation reaction, to maintain the driving force for hydrogen dissolution into the oil phase, to control the temperature rise of the catalyst bed in the catalytic distillation hydrogenation tower 1, and to dilute the concentration of olefins and impurities in the light components, promoting olefin hydrogenation saturation and impurity removal reactions. The function of the fresh hydrogen is to replenish the hydrogen consumed by the composite oil during the hydrogenation process.

[0101] In addition, during the hydrogenation process of the light components in the composite oil, hydrogen is mainly consumed in the following four aspects: chemical hydrogen consumption; equipment leakage; dissolution loss; and release loss. According to the chemical reaction formula, every 1 mole of olefin in the composite oil requires 1 mole of hydrogen. Therefore, the vast majority of new hydrogen is consumed in the chemical reaction, that is, in the olefin saturation and impurity removal of the light components in the composite oil.

[0102] It should be noted that for the hydrotreating reaction of composite oils, the main hydrotreating catalysts that can be used include supported noble metal catalysts and bimetallic catalysts. Generally speaking, both types of catalysts can meet the specifications of the hydrotreated products. Among them, noble metal catalysts have higher activity than bimetallic catalysts, and they require a lower reaction inlet temperature. However, the biggest advantage of bimetallic catalysts is their lower price and stronger tolerance to impurities such as sulfur and arsenic in the feedstock. A comparison of the characteristics of the two catalyst systems is shown in Table 2.

[0103] Table 2 Comparison of Noble Metal and Bimetallic Hydrogenation Saturated Catalysts

[0104] project precious metals Non-precious metals Reactivity higher lower reaction temperature Low high Olefin conversion excellent good Hydrogen-to-oil ratio Low high Sulfur tolerance Difference excellent Selective excellent good life Highly dependent on raw materials Longer The initial cost of a catalyst high Low

[0105] Because the reaction temperature and pressure required for the hydrogenation saturation of C8 olefins in the light components are relatively low, and because sulfides such as dimethyl disulfide and diethyl disulfide have high boiling points, most of these sulfides are concentrated in the bottom of the catalytic distillation hydrogenation tower under the action of fractionation. Therefore, there are fewer harmful impurities such as sulfides in the C8 olefins in the upper part of the catalytic distillation hydrogenation tower 1. Thus, a non-precious metal catalyst with lower activity, higher reaction temperature and pressure but stronger anti-pollution ability can be preferentially packed in the lower part of the catalyst bed in the reaction section of the catalytic distillation hydrogenation tower 1. A precious metal catalyst (such as palladium or platinum) with higher activity, lower reaction temperature and pressure but weaker anti-pollution ability with an active component content of 0.1% to 0.6% can be preferentially packed in the upper part of the catalyst bed in the reaction section of the catalytic distillation hydrogenation tower 1. For example, the content of the active component can be 0.1%, 0.3%, 0.5%, or 0.6%, etc., and the volume of precious metal catalyst in the upper part of the reaction section of the catalytic distillation hydrogenation tower 1 accounts for 20% to 80% of the total volume of catalyst in the reaction section. Depending on the specific circumstances, the reaction section of the catalytic distillation hydrogenation tower 1 can be entirely filled with either a precious metal catalyst or a non-precious metal catalyst.

[0106] It is worth noting that the heat released during the hydrogenation saturation reaction of C8 olefins is utilized for the separation of light and heavy components in the composite oil, thus reducing energy consumption. Furthermore, distillation allows for the separation of harmful substances from the reacting components in the composite oil before they enter the catalyst bed, thereby extending the catalyst's lifespan. Moreover, distillation can separate the reacting C8 olefins from the non-reacting C... 12 Olefins and C 16 Olefins are separated before entering the catalyst bed, thereby improving the selectivity of the reaction and reducing the severity of the reaction.

[0107] Step 302: The first component is condensed and cooled by the condenser 2 and then enters the reflux tank 3. Gas-liquid separation is carried out in the reflux tank 3. The separated gas phase product is changed by the first compressor 5 and then enters the hydrogenation reactor 6 as circulating hydrogen. The separated liquid phase product is returned to the catalytic distillation hydrogenation tower 1.

[0108] It should be noted that the main components of the first component are C8 alkanes generated by hydrogenation of C8 olefins in the composite oil, hydrogen, and a small amount of small molecule hydrocarbons generated by cracking.

[0109] It should be noted that all liquid products are refluxed into the catalytic distillation hydrogenation tower 1, and the reflux flow rate is 1 to 10 times the mass flow rate of the first hydrogenation product, i.e., isooctane. For example, it can be 1, 3, 5, 7, or 10 times.

[0110] It should be noted that the liquid product can be refluxed into the catalytic distillation hydrogenation tower 1 to flush the hydrogenation catalyst in the catalytic distillation hydrogenation tower 1, thereby delaying the deactivation time of the hydrogenation catalyst and extending its service life.

[0111] Step 303: The second component is divided into three parts in the bottom section of the catalytic distillation hydrogenation tower 1 to obtain the first product, the second product and the third product; the first product is fed into the catalyst bed of the hydrogenation reactor 6 as quench oil and is used to control the temperature rise of the catalyst bed; the second product is fed into the hydrogenation reactor 6 as feed and mixed with recycled hydrogen and fresh hydrogen; the third product is either used as a separate heavy oil product output device or mixed with the first hydrogenation product as the target hydrogenation product output device.

[0112] It should be noted that the second component mainly includes C 12 Alkanes and C 16 Alkanes, and unreacted C 12 Olefins and C 16 Olefins. The first, second, and third products all contain C2O4. 12 Alkanes and C 16 Alkanes, and unreacted C 12 Olefins and C 16 Olefins.

[0113] It should be noted that the mass ratio of the first product to the third product is 1 to 3:1; the mass ratio of the second product to the third product is 2 to 3:1. For example, the mass ratio of the first product to the third product can be 1:1, 2:1, or 3:1, etc.; the mass ratio of the second product to the third product can be 2:1, 2.5:1, or 3:1, etc.

[0114] It should be noted that the hydrogenation catalyst in the hydrogenation reactor 6 can preferably be a bimetallic component with low activity, high reaction temperature and pressure but strong anti-pollution ability, such as nickel / molybdenum, nickel / cobalt, etc. The content of the active component is 20% to 80%. For example, the content of the active component can be 20%, 40%, 60% or 80%, etc.

[0115] It should be noted that the second product undergoes a hydrogenation reaction in hydrogenation reactor 6, including the following operating conditions: a reaction temperature of 200–350°C and a reaction pressure of 2.0–5.0 MPa. For example, the reaction temperature can be 200°C, 250°C, 300°C, or 350°C, and the reaction pressure can be 2.0 MPa, 3.0 MPa, 4.0 MPa, or 5.0 MPa, etc.

[0116] It should be noted that fresh hydrogen can be added to the inlet of hydrogenation reactor 6. There are two methods of addition: the first is to directly inject fresh hydrogen into the inlet of hydrogenation reactor 6, and the second is to indirectly control the amount of fresh hydrogen injected into the catalytic distillation hydrogenation tower 1. To reduce equipment and operating costs, the second method of adding fresh hydrogen is preferred.

[0117] Step 304: After the second product flows out from the bottom of the catalytic distillation hydrogenation tower 1, it mixes with recycled hydrogen and fresh hydrogen and enters the hydrogenation reactor 6. In the hydrogenation reactor 6, it contacts the hydrogenation catalyst to carry out a catalytic hydrogenation reaction and obtain the second hydrogenation product.

[0118] It should be noted that the second product includes C. 12 Alkanes and C 16 Alkanes, and C 12 Olefins and C 16 Olefins.

[0119] It should be noted that both recycled hydrogen and fresh hydrogen are used to provide hydrogen for the hydrogenation of the second product.

[0120] Step 305: The second hydrogenation product enters the catalytic distillation hydrogenation tower 1 from the bottom of the hydrogenation reactor 6. The hydrogen carried in the second hydrogenation product is separated by the catalytic distillation hydrogenation tower 1 and used to replenish the hydrogen required for hydrogenation in the catalytic distillation hydrogenation tower.

[0121] It should be noted that the remaining portion of the second hydrogenation product, excluding hydrogen gas, includes: C 12 Alkanes and C 16 Alkanes, and unreacted C 12 Olefins and C 16 Olefins.

[0122] The target hydrogenated product obtained by the hydrogenation method for producing isooctane using the embodiments of this application has low saturated vapor pressure, high octane number, no or low sulfur content, and low olefin content, making it a high-quality clean gasoline blending component. Furthermore, compared to conventional processes, it eliminates the need for equipment such as reaction product coolers, high-pressure separators, product stripping towers, and associated overhead reflux and bottom reboiling systems, thus reducing investment costs.

[0123] Furthermore, the method provided in this application embodiment can also produce the first hydrogenation product, namely isooctane, as needed; the first hydrogenation product can also be directly mixed with the third product, and the mixed product can be used as a high-quality gasoline blending component to be added to the gasoline pool of the entire plant.

[0124] To make the technical solutions and advantages of this application clearer, the following will describe them in detail through optional embodiments.

[0125] Example 1

[0126] The composition of the composite oil produced by isobutylene oligomerization at a certain oil refinery is shown in Table 3. The composite oil flow rate is 10.0 tons / hour, and the annual processing capacity is 84,000 tons. The sulfur content in the composite oil is 40 mg / kg.

[0127] Table 3 Composition of Composite Oil

[0128]

[0129] To produce gasoline blending components that meet the requirements of olefin volume fraction ≤15% as specified in the automotive gasoline standard (GB 17930-2016), the blended oil is processed using the hydrogenation device provided in the embodiments of this application. The main operating conditions are shown in Table 4.

[0130] Table 4 Main Equipment Operating Conditions

[0131]

[0132]

[0133] In catalytic distillation hydrogenation column 1, the single-pass conversion of C8 olefins to C8 alkanes by hydrogenation to saturation is 99%; in hydrogenation reactor 6, C... 12 Alkenes are hydrogenated to saturate C 12 The single-pass conversion rate of alkanes is 98%, C 16 Alkenes are hydrogenated to saturate C 16 The single-pass conversion rate of alkanes is 95%, and there are also 0.5% and 1.5% C₂ and C₃ respectively. 12 Olefins and C 16Olefins are cracked into smaller olefins, which are then hydrogenated to form smaller alkanes. Additionally, during fractionation, 25% (by mass) of the sulfides enter the catalyst bed of catalytic distillation hydrogenation tower 1 along with the C8 olefins, while the remaining 75% of the sulfides are carried away by the C8 olefins. 12 Olefins and C 16 Olefins flow to the bottom of the column and eventually enter the catalyst bed in the hydrogenation reactor 6. Under the action of the hydrogenation catalyst, these sulfides can be completely converted into H2S through the hydrogenation reaction. Then, the H2S leaves the top of the catalytic distillation hydrogenation column 1 with the circulating hydrogen and is removed by setting up a circulating hydrogen desulfurization column or by emitting purge gas.

[0134] The flow rate and composition of the resulting isooctane and heavy oil mixture after hydrogenation are shown in Table 5.

[0135] Table 5 Composition and flow rate of isooctane and heavy oil mixture

[0136]

[0137] As can be seen from Table 5, after processing with the hydrogenation device provided in this application, the produced isooctane and heavy oil mixture is sulfur-free and benzene-free, with an olefin mass content of 4.18% and a liquid standard volume content of 3.92%. Therefore, the product of isooctane and heavy oil mixture is a high-quality clean gasoline blending component.

[0138] Example 2

[0139] The feed rate to the hydrogenation reactor was 3000 kg / h, and other conditions were the same as in Example 1. The flow rate and composition of the resulting isooctane and heavy oil mixture after hydrogenation are shown in Table 6.

[0140] Table 6 Composition and flow rate of isooctane and heavy oil mixture

[0141]

[0142] As can be seen from Table 6, the olefin content of the produced isooctane and heavy oil mixture is 2.88% by mass and 2.72% by liquid standard volume, which are 1.30 percentage points and 1.20 percentage points lower than those in Example 1, respectively. This indicates that when the reactor feed flow rate and quench oil flow rate increase, that is, when the material circulation between catalytic distillation hydrogenation tower 1 and hydrogenation reactor 6 increases, the olefin content in the mixture will decrease.

[0143] Example 3

[0144] The produced isooctane was discharged separately as a product, and other conditions were the same as in Example 2.

[0145] After hydrogenation, the produced isooctane contains 77.0% (by mass) 2,4,4-trimethylpentane, which is discharged separately as a product. The composition and flow rate of the produced heavy oil are shown in Table 7. As can be seen from Table 7, the heavy oil product contains C... 12 Olefins, C 16 The volume fractions of olefins were 19.40% and 0.75%, respectively, with a total integral of 20.15% and a standard liquid flow rate of 1.34 m³. 3 Its volumetric flow rate is very small, accounting for only 134.00 m³ of the total raw gasoline in the refinery's gasoline pool. 3 / h 1.0%. After being added to the gasoline blending tank of the plant, the total olefin volume content of the gasoline tank increased from the original 14.12% to 14.18%, a very small increase. After blending, the olefin volume fraction meets the requirement of ≤15%.

[0146] Table 7 Heavy Oil Composition and Flow Rate

[0147]

[0148]

[0149] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A hydrotreating unit for producing isooctane, characterized in that, The apparatus includes: a catalytic distillation hydrogenation tower (1), a condenser (2), a reflux tank (3), a reboiler (4), a first compressor (5), and a hydrogenation reactor (6); The top of the catalytic distillation hydrogenation tower (1) is connected to the condenser (2), the condenser (2) is connected to one inlet of the reflux tank (3), one outlet of the reflux tank (3) is connected to the first compressor (5), and the other outlet of the reflux tank (3) is connected to the catalytic distillation hydrogenation tower (1); one end of the reboiler (4) is connected to the bottom of the catalytic distillation hydrogenation tower (1), and the other end of the reboiler (4) is connected to the catalytic distillation hydrogenation tower (1); the bottom of the hydrogenation reactor (6) is connected to the catalytic distillation hydrogenation tower (1). The catalytic distillation hydrogenation tower (1) is used to receive the composite oil and fresh hydrogen from outside the device, the reflux liquid from the reflux tank (3), and the gas-liquid two-phase mixture from the reboiler (4); and to separate the light and heavy components of the composite oil, and to perform a hydrogenation reaction on the light component to obtain a first component, a second component, and a first hydrogenation product, wherein the first hydrogenation product is drawn from the side stream of the catalytic distillation hydrogenation tower (1); the first component is discharged from the top of the catalytic distillation hydrogenation tower (1) and sequentially enters the condenser (2). The second component is divided into three parts in the bottom section of the catalytic distillation hydrogenation tower (1) to obtain a first product, a second product and a third product, wherein the third product is output as a heavy oil product from the device; the first product is fed into the catalyst bed of the hydrogenation reactor (6) as quench oil in the hydrogenation reactor (6), and the first product is used to control the temperature rise of the catalyst bed; and the second product is fed into the hydrogenation reactor (6) as feed. The condenser (2) is used to condense and cool the first component; The reflux tank (3) is used to perform gas-liquid separation on the first component after condensation and cooling to obtain gaseous products and liquid products. A portion of the gaseous products enters the first compressor (5), and the other portion of the gaseous products is discharged as purge gas. The reboiler (4) is used to provide a heat source for the catalytic distillation hydrogenation tower (1), wherein the feed of the reboiler (4) is taken out at the bottom of the bottom of the catalytic distillation hydrogenation tower (1); The first compressor (5) is used to change the pressure of the gaseous product entering the first compressor (5) and to transport the gaseous product after pressure change as circulating hydrogen to the hydrogenation reactor (6); The hydrogenation reactor (6) is used to hydrogenate the second product to obtain a second hydrogenated product; The catalytic distillation hydrogenation tower (1) is also used to receive the second hydrogenation product delivered from the bottom of the hydrogenation reactor (6). The hydrogen carried in the second hydrogenation product is separated by the catalytic distillation hydrogenation tower (1) and used to replenish the hydrogen required for the hydrogenation reaction in the catalytic distillation hydrogenation tower (1).

2. The apparatus as claimed in claim 1, characterized in that, The device further includes: a first product pump (7) and a first cooler (8); The inlet of the first product pump (7) is connected to the catalytic distillation hydrogenation tower (1), and the outlet of the first product pump (7) is connected to the first cooler (8). The first product pump (7) is used to change the pressure of the first hydrogenated product coming out of the catalytic distillation hydrogenation tower (1), and the first cooler (8) is used to cool the first hydrogenated product so that the temperature of the first hydrogenated product reaches the required output temperature.

3. The apparatus as described in claim 1, characterized in that, The device also includes: a feed heat exchanger (9), a second cooler (10), a circulation pump (11), and a second product pump (12); The feed heat exchanger (9) is connected to the catalytic distillation hydrogenation tower (1), and the feed heat exchanger (9) is also connected to the second cooler (10); The second cooler (10) is connected to the circulation pump (11), and the second cooler (10) is also connected to the second product pump (12), and the circulation pump (11) is connected to the hydrogenation reactor (6).

4. The apparatus as claimed in claim 1, characterized in that, The device further includes: a feed pump (13) and a feed heater (14); The inlet of the feed pump (13) is connected to the bottom of the catalytic distillation hydrogenation tower (1), the outlet of the feed pump (13) is connected to one side of the feed heater (14), and the other side of the feed heater (14) is connected to the top of the hydrogenation reactor (6).

5. The apparatus as claimed in claim 1, characterized in that, The device further includes: a reflux pump (15); The inlet of the reflux pump (15) is connected to the bottom of the reflux tank (3), and the outlet of the reflux pump (15) is connected to the top of the catalytic distillation hydrogenation tower (1). The reflux pump (15) is used to reflux the liquid phase separated from the reflux tank (3) back to the catalytic distillation hydrogenation tower (1).

6. The apparatus as claimed in claim 4, characterized in that, The device further includes: a second compressor (16); The second compressor (16) is connected to the feed heater (14) and is used to change the pressure of hydrogen from the outside.

7. A method for hydrogenating a composite oil capable of producing isooctane, said method being used in the apparatus according to any one of claims 1-6, characterized in that, The method includes the following steps: The composite oil and the new hydrogen from the outside world enter the catalytic distillation hydrogenation tower (1) respectively and the light components and heavy components are separated in the catalytic distillation hydrogenation tower (1). The light components are contacted with the hydrogenation catalyst in the catalytic distillation hydrogenation tower (1) to carry out catalytic hydrogenation reaction. The first component, the second component and the first hydrogenation product are obtained in the catalytic distillation hydrogenation tower (1). The first component is condensed and cooled by the condenser (2) and then enters the reflux tank (3). Gas-liquid separation is performed in the reflux tank (3). The separated gas phase product is changed by the first compressor (5) and then enters the hydrogenation reactor (6) as circulating hydrogen. The separated liquid phase product is returned to the catalytic distillation hydrogenation tower (1). Among them, some gas is discharged as purge gas to other devices for further treatment before entering the first compressor (5). The second component is divided into three parts in the bottom section of the catalytic distillation hydrogenation tower (1) to obtain a first product, a second product and a third product; the first product is fed into the catalyst bed of the hydrogenation reactor (6) as quench oil, and the first product is used to control the temperature rise of the catalyst bed; the second product is fed into the hydrogenation reactor (6) as feed and mixed with the circulating hydrogen and the fresh hydrogen; the third product is either used as a separate heavy oil product output device or mixed with the first hydrogenation product as a target hydrogenation product output device. After the second product flows out from the bottom of the catalytic distillation hydrogenation tower (1), it mixes with the recycled hydrogen and the new hydrogen and enters the hydrogenation reactor (6). In the hydrogenation reactor (6), it contacts the hydrogenation catalyst to carry out a catalytic hydrogenation reaction and obtain the second hydrogenation product. The second hydrogenation product enters the catalytic distillation hydrogenation tower (1) from the bottom of the hydrogenation reactor (6). The hydrogen carried in the second hydrogenation product is separated by the catalytic distillation hydrogenation tower (1) and used to replenish the hydrogen required for the hydrogenation reaction in the catalytic distillation hydrogenation tower (1).

8. The method as described in claim 7, characterized in that, The molar ratio of hydrogen required in the catalytic distillation hydrogenation tower (1) to isooctene in the composite oil is 1.5 to 3:

1.

9. The method as described in claim 7, characterized in that: The mass ratio of the first product to the third product is 1 to 3:1; The mass ratio of the second product to the third product is 2 to 3:

1.

10. The method as described in claim 7, characterized in that... After the second product flows out from the bottom of the catalytic distillation hydrogenation tower (1), it is mixed with the circulating hydrogen and the new hydrogen and then enters the hydrogenation reactor (6). In the hydrogenation reactor (6), it comes into contact with the hydrogenation catalyst to carry out a catalytic hydrogenation reaction and obtain the second hydrogenation product. The reaction is carried out under the following operating conditions: reaction temperature 200-350°C, reaction pressure 2.0-5.0 MPa.

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