A method and device for enhancing the hydrogenation depth of polycyclic aromatic hydrocarbons in fortified heavy aromatic oil

Abstract

The present invention belongs to the fields of chemical engineering and chemical reaction engineering, and provides a method and a device for enhancing the hydrogenation depth of polycyclic aromatic hydrocarbons in heavy aromatics oil. The device is composed of a hydrogen and heavy aromatics oil flow control unit, a strengthened mixer series fixed bed reactor unit, and a gas-liquid separation unit, and the units are connected in series in sequence through pipelines. The strengthened mixer series fixed bed reactor unit includes a strengthened mixer, a short-distance cone tube, and a fixed bed reactor that are connected in sequence. A multi-section temperature-controlled electric heating furnace is arranged outside the fixed bed reactor, and the strengthened mixer is integrated into the inlet of the fixed bed reactor through the short-distance cone tube. The device is used to achieve continuous micron-level mixing of gas phase and liquid phase under the conditions that the hydrogen-oil ratio is higher than 860:1 and the conversion rate of condensed ring aromatic hydrocarbons is not less than 70%. By forming a continuous micron-level gas-liquid two-phase fluid, the hydrogenation depth of polycyclic aromatic hydrocarbons in heavy aromatics oil is increased.

Description

Technical Field

[0001] The present invention belongs to the fields of chemical engineering and chemical reaction engineering. Specifically, it relates to a method and device for enhancing the hydrogenation depth of polycyclic aromatic hydrocarbons in heavy aromatics oil. Background Art

[0002] Hydrogenation of heavy aromatics oil is an important method for the lightening of heavy aromatics oil. By hydrogenation, bicyclic and polycyclic aromatic hydrocarbons such as naphthalene, phenanthrene, and anthracene in heavy aromatics oil are converted into monocyclic aromatic hydrocarbons, which are high-quality raw materials for producing high-value chemical products such as benzene, toluene, and xylene. Hydrogenation of heavy aromatics oil is a typical reaction with high hydrogen consumption. The gas-liquid mixing effect of hydrogen and heavy aromatics oil, as well as the mass transfer and dissolution of hydrogen in heavy aromatics oil, are important factors affecting the hydrogenation efficiency of heavy aromatics oil. However, the solubility of hydrogen in heavy aromatics oil is relatively low. Therefore, in the process of deep hydrogenation of heavy aromatics oil, hydrogen in the gas phase needs to be transferred by diffusion to the active centers of the catalyst. In order to improve the efficiency of the catalytic hydrogenation reaction of heavy aromatics oil, hydrogenation of heavy aromatics oil is usually carried out under high pressure and a large hydrogen-to-oil ratio, which significantly increases hydrogen consumption and energy consumption. Especially under mass transfer control or conditions of high conversion of polycyclic aromatic hydrocarbons, the mass transfer efficiency of gaseous hydrogen in heavy aromatics oil is a key control factor for enhancing the hydrogenation depth of polycyclic aromatic hydrocarbons in heavy aromatics oil.

[0003] At present, hydrogenation reactors are mainly divided into two categories. One is the conventional hydrogenation reactor. The gas-liquid two-phase from the reactor inlet first passes through the inlet distributor. After being rectified by the upper conical body, it is throttled and collided through the two layers of holes of the upper and lower baffles and then diffused to the entire reactor interface. After being distributed by the distribution plate, it contacts the catalyst bed. This kind of distributor and distribution plate can achieve the uniform distribution of hydrogen in the hydrogenation reactor bed and promote the mixing of gas-liquid two-phase, but cannot strengthen the mixing of gas-liquid. The other is to change the continuous gas phase into micron-sized bubbles of the discontinuous phase through a strengthening device, and then mix it with the continuous oil phase, and use the high specific surface area and surface energy of the micron-sized bubbles to strengthen the mass transfer between gas-liquid two-phase. Chinese Patent CN116790285A discloses a method and device for supergravity-enhanced diesel hydrogenation refining. A supergravity mixing device is connected in series at the front end of the hydrogenation device inlet. The micro-nano fillers on the rotor in the device break hydrogen under the action of high-speed rotation to form bubbles with a scale of 10-200 μm and mix with the liquid phase oil to achieve the purpose of strengthening the mixing and mass transfer of gas-liquid two-phase, and then improve the efficiency of diesel hydrogenation. Chinese Patent CN112175667A discloses a micro-interface enhanced reaction system and method for hydrogenation of mixed oil. The micro-interface generator converts the pressure energy of hydrogen and / or the kinetic energy of liquid into the surface energy of hydrogen bubbles, and breaks the continuous-phase hydrogen into micro-bubbles with a size of 1 μm to 1 mm and then mixes with the liquid to achieve the strengthening of the mixing of gas-liquid two-phase. The micro-bubbles of hydrogen are used to increase the mass transfer area between gas-liquid two-phase, strengthen the mass transfer process of hydrogen in the hydrogenation reaction process, and strengthen the reaction efficiency between the mixed oil and hydrogen. Chinese Patent CN110396425A discloses a device and method for micro-interface enhanced liquid-phase circulating hydrogenation. The micro-bubble generator is used to convert the continuous-phase hydrogen into micron-sized bubbles and mix with the continuous-phase liquid to form a pseudo-homogeneous gas-liquid mixture flow. Similarly, by using the increased mass transfer area between gas-liquid two-phase, the mixing and mass transfer process between hydrogen and liquid raw materials is strengthened. A large number of micro-bubbles in the liquid phase strengthen the mass transfer process of hydrogen dissolved in the liquid phase during the hydrogenation reaction process. The space utilization efficiency of the liquid-phase circulating hydrogenation reactor is effectively improved. Chinese Patent CN110652941A discloses a micro-bubble hydrogenation reactor, which disperses micro-bubbles into the liquid-phase oil to increase the mass transfer area between gas-liquid two-phase and strengthen the mass transfer process between gas-liquid two-phase.

[0004] In the above hydrogenation enhancement reaction, the liquid is the continuous phase and the micro-bubbles are the dispersed phase, which is only applicable to the reaction with a relatively small hydrogen-oil ratio or a relatively low hydrogen consumption, and is not applicable to the deep hydrogenation reaction of polycyclic aromatic hydrocarbons in heavy aromatic oil with a large hydrogen consumption. Summary of the Invention

[0005] In view of the characteristics of high hydrogen consumption and high hydrogen-oil ratio in the hydrogenation of polycyclic aromatic hydrocarbons in heavy aromatics, the present invention proposes a method and device for enhancing the hydrogenation depth of polycyclic aromatic hydrocarbons in heavy aromatic oil. Under the conditions that the hydrogen-oil ratio is higher than 860:1 and the conversion rate of condensed polycyclic aromatic hydrocarbons is not less than 70%, the intensifying mixer is integrated into the inlet of the fixed-bed reactor through a short-distance tapered pipe. The intensifying mixer changes the mixing scale of the gas-liquid two-phase, realizes the micron-scale mixing of hydrogen and heavy aromatic oil two-phase, and improves the hydrogenation depth of polycyclic aromatic hydrocarbons in heavy aromatic oil by forming a continuous micron-scale gas-liquid two-phase fluid.

[0006] The object of the present invention is achieved by the following technical solutions:

[0007] On the one hand, the present invention provides a device for enhancing the hydrogenation depth of polycyclic aromatic hydrocarbons in heavy aromatic oil, which is composed of a hydrogen and heavy aromatic oil metering and control unit, an intensifying mixer in series with a fixed-bed reactor unit and a gas-liquid separation unit. Each unit is connected in series through pipelines in turn. It is characterized in that the intensifying mixer in series with the fixed-bed reactor unit includes an intensifying mixer, a short-distance tapered pipe, and a fixed-bed reactor connected in sequence. A multi-section temperature-controlled electric heating furnace is arranged outside the fixed-bed reactor. The intensifying mixer is integrated into the inlet of the fixed-bed reactor through the short-distance tapered pipe. This device is used to realize the micron-scale mixing of continuous gas phase and liquid phase under the conditions that the hydrogen-oil ratio is higher than 860:1 and the conversion rate of condensed polycyclic aromatic hydrocarbons is not less than 70%.

[0008] Furthermore, the sizes of both ends of the short-distance tapered pipe match the outlet size of the intensifying mixer and the inlet size of the fixed-bed reactor respectively, and the length of the short-distance tapered pipe is 3 - 8 cm, preferably 5 cm. The distance between the intensifying mixer and the fixed-bed reactor is short. Connecting through the short-distance tapered pipe avoids the destruction of the micron-scale fluid flow pattern formed in the intensifying mixer. The gas-liquid two-phase continuous fluid leaving the short-distance tapered pipe directly enters the catalyst bed layer, retaining the micron-scale flow pattern formed by the gas-liquid two-phase fluid in the mixer to the greatest extent.

[0009] Furthermore, the hydrogen and heavy aromatic oil metering and control unit includes a gas feeding unit and a liquid feeding unit. The gas feeding unit includes a gas feeding pipe and a pressure reducing valve, a pressure gauge, a stop valve, and a gas mass flowmeter installed on the gas feeding pipe. One end of the gas feeding pipe is connected to a gas supply source. The liquid feeding unit includes a liquid feeding pipe and a stop valve and a liquid metering pump arranged on the liquid feeding pipe. One end of the liquid feeding pipe is connected to a liquid supply source; the other ends of the gas feeding pipe and the liquid feeding pipe are both connected to the inlet of the intensifying mixer.

[0010] Furthermore, the fixed-bed reactor is successively from top to bottom a quartz sand bed layer, a catalyst bed layer, and a quartz sand bed layer.

[0011] Furthermore, the gas-liquid separation unit comprises a high-pressure gas-liquid separator, a low-pressure gas-liquid separator and a liquid storage tank which are connected in sequence, and the outlet of the fixed bed reactor is connected to the inlet of the high-pressure gas-liquid separator.

[0012] Further, the intensified mixer is a mixer capable of achieving two-phase micron-level mixing of hydrogen and heavy aromatic oil under a large hydrogen-to-oil ratio. Further preferably, the mixer is a microchannel mixer or a static mixer, and the microchannel mixer is preferably a separation-recombination type (CPMM) microchannel mixer or a cross-finger type (SIMM) microchannel mixer. The CPMM type microchannel mixer and the SIMM type microchannel mixer are the same as those mentioned in Chinese patent CN117753316A.

[0013] On the other hand, the present invention provides a method for an apparatus for enhancing the hydrogenation depth of polycyclic aromatic hydrocarbons in heavy aromatic oil. Under the conditions that the hydrogen-to-oil ratio is higher than 860:1 and the conversion rate of polycyclic aromatic hydrocarbons is not less than 70%, hydrogen and heavy aromatic oil are introduced into the inlet of an enhanced mixer through a hydrogen and heavy aromatic oil metering control unit, a continuous fluid of a gas-liquid two-phase micron-level mixture is formed in the enhanced mixer, and then the continuous fluid of the gas-liquid two-phase micron-level mixture is introduced into a catalyst bed of a fixed bed reactor in a downward manner through a short-distance conical tube to undergo a hydrogenation reaction, and the reacted fluid flows out from the outlet of the fixed bed reactor and enters the inlet of a high-pressure gas-liquid separator, and the gas-liquid two-phase separation is performed in the gas-liquid separation unit.

[0014] Furthermore, the heavy aromatic oil contains monocyclic aromatic hydrocarbons, bicyclic aromatic hydrocarbons and condensed-ring aromatic hydrocarbons.

[0015] Furthermore, the micron-scale mixing means that the gas-liquid two-phase mixing scale is ≤10 μm.

[0016] Furthermore, the hydrogen-to-oil ratio is 860 / 1-1200 / 1.

[0017] Furthermore, the mixing conditions in the intensified mixer are: the temperature is -30°C to 300°C, more preferably 50°C to 90°C; and the mixing pressure is the same as that of the fixed bed hydrogenation reactor.

[0018] Furthermore, the conditions of the hydrogenation reaction are: pressure 1 MPa ~ 20 MPa, more preferably 3 MPa ~ 6 MPa; liquid hourly volume space velocity 0.1 h -1 ~5.0 h -1 , and more preferably 0.9 h -1 ~3.5 h -1 ; The reaction temperature is 120°C to 420°C, more preferably 140°C to 300°C,

[0019] Further, the hydrogenation reaction catalyst is a highly active hydrogenation catalyst. Further, it is preferably Pt / Al2O3, Pd / Al2O3, Pt-Pd / Al2O3 or a highly active Ni-based catalyst, and the highly active Ni-based catalyst is one of Ni / MCM-41, Ni / C and Ni / Al2O3.

[0020] Further, before entering the fixed-bed reactor, the gas-liquid two-phase is simultaneously passed through a intensifying mixer to achieve micron-scale mixing, enhancing the mass transfer efficiency between the gas and liquid phases. By utilizing the rapid diffusion advantage between micron-scale two-phase fluids, the mass transfer process of hydrogen during the reaction is improved, and further the purpose of increasing the hydrogenation depth of polycyclic aromatic hydrocarbons in heavy aromatic oil under high conversion rate is achieved.

[0021] The advantages and beneficial effects of the present invention are as follows:

[0022] (1) The device of the present invention integrates an intensifying mixer into the inlet of the fixed-bed reactor through a short-distance conical tube, avoiding the destruction of the micron-scale fluid flow pattern formed in the intensifying mixer. The continuous gas-liquid two-phase fluid leaving the short-distance conical tube directly enters the catalyst bed layer, retaining to the greatest extent the micron-scale flow pattern formed by the gas-liquid two-phase fluid in the mixer, thereby increasing the hydrogenation depth.

[0023] (2) Under the conditions that the hydrogen-oil ratio is higher than 860:1 and the conversion rate of condensed polycyclic aromatic hydrocarbons is not less than 70%, the method of the present invention changes the mixing scale of the gas-liquid two-phase through an intensifying mixer, realizes the micron-scale mixing of hydrogen and heavy aromatic oil, and realizes enhanced mass transfer by forming a continuous micron-scale gas-liquid two-phase fluid, increasing the hydrogenation depth of polycyclic aromatic hydrocarbons in heavy aromatic oil, and the hydrogenation depth of polycyclic aromatic hydrocarbons is higher than that of a conventional fixed-bed hydrogenation reaction device.

[0024] (3) The method and device of the present invention have a wide range of applications. The device has a simple structure and a large adjustable range of gas flow. In addition to being applicable to gas-liquid-solid three-phase high-hydrogen-consumption and deep hydrogenation reactions, it is also applicable to the deep hydrogenation of organic liquids with a relatively fast reaction rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a device for enhancing the hydrogenation depth of polycyclic aromatic hydrocarbons in heavy aromatic oil according to the present invention.

[0026] Figure 2 It is a conventional fixed-bed reaction device of Comparative Example 1.

[0027] Among them, Ⅰ - hydrogen and heavy aromatic oil metering and control unit, Ⅱ - intensified mixer series fixed bed reactor unit, Ⅱ” - fixed bed reactor unit, Ⅲ - gas-liquid separation unit; 1 - pressure reducing valve, 2 - pressure gauge, 3 - globe valve, 4 - gas mass flowmeter, 5 - liquid metering pump; 6 - intensified mixer, 7 - short-distance cone tube, 8 - fixed bed reactor, 9 - multi-section temperature-controlled electric heating furnace, 10 - high-pressure gas-liquid separator, 11 - low-pressure gas-liquid separator, 12 - liquid storage tank. Specific embodiments

[0028] The present invention will be further described in detail below in conjunction with the accompanying drawings and through specific embodiments. The following embodiments are only descriptive and not restrictive, and the protection scope of the present invention cannot be limited thereby.

[0029] Example 1

[0030] As Figure 1 shown, a device for intensifying the hydrogenation depth of polycyclic aromatic hydrocarbons in heavy aromatic oil is composed of a hydrogen and heavy aromatic oil metering and control unit Ⅰ, an intensified mixer series fixed bed reactor unit Ⅱ and a gas-liquid separation unit Ⅲ. The units are connected in series in sequence through pipelines.

[0031] The hydrogen and heavy aromatic oil metering and control unit Ⅰ includes a gas feed unit and a liquid feed unit. The gas feed unit includes a gas feed pipe and a pressure reducing valve 1, a pressure gauge 2, a globe valve 3 and a gas mass flowmeter 4 installed on the gas feed pipe. One end of the gas feed pipe is connected to a gas supply source. The liquid feed unit includes a liquid feed pipe and a globe valve 3 and a liquid metering pump 5 arranged on the liquid feed pipe. One end of the liquid feed pipe is connected to a liquid supply source. The other ends of the gas feed pipe and the liquid feed pipe are both connected to the inlet of the intensified mixer 6.

[0032] The intensified mixer series fixed bed reactor unit Ⅱ includes an intensified mixer 6, a short-distance cone tube 7 and a fixed bed reactor 8 connected in sequence. A multi-section temperature-controlled electric heating furnace 9 is arranged outside the fixed bed reactor 8. The outlet of the intensified mixer 6 integrates the intensified mixer 6 into the inlet of the fixed bed reactor 8 through the short-distance cone tube 7. This device is used to achieve continuous micron-scale mixing of gas phase and liquid phase under the conditions that the hydrogen-oil ratio is higher than 860:1 and the conversion rate of condensed polycyclic aromatic hydrocarbons is not less than 70%. The sizes of both ends of the short-distance cone tube 7 match the outlet size of the intensified mixer 6 and the inlet size of the fixed bed reactor 8 respectively, and the suitable length is 3 - 8 cm, preferably 5 cm. The distance between the intensified mixer 6 and the fixed bed reactor 8 is short. Connecting through the short-distance cone tube 7 avoids the destruction of the micron-scale fluid flow pattern formed in the intensified mixer 6. The continuous gas-liquid two-phase fluid leaving the short-distance cone tube 7 directly enters the catalyst bed layer, retaining the micron-scale flow pattern of the gas-liquid two-phase fluid formed in the intensified mixer 6 to the greatest extent.

[0033] In the fixed-bed reactor 8, there are successively a quartz sand bed, a catalyst bed, and a quartz sand bed. The gas-liquid separation unit III includes a high-pressure gas-liquid separator 10, a low-pressure gas-liquid separator 11, and a liquid storage tank 12 connected in sequence. The outlet of the fixed-bed reactor 8 is connected to the inlet of the high-pressure gas-liquid separator 10. The intensifying mixer 6 is a CPMM type microchannel mixer.

[0034] Comparative Example 1

[0035] As Figure 2 shown, a conventional fixed-bed reaction device, the difference from Example 1 is only that the fixed-bed reactor unit II is different. Before the fixed-bed reactor 8, the intensifying mixer 6 and the short-distance conical pipe 7 are not installed. The other ends of the gas feed pipe and the liquid feed pipe are both connected to the three-way inlet at the inlet of the fixed-bed reactor, and the three-way outlet is connected to the fixed-bed reactor inlet.

[0036] Example 2

[0037] The difference from Example 1 is only that the intensifying mixer 6 is a SIMM type microchannel mixer.

[0038] Example 3

[0039] A method for a device for intensifying the hydrogenation depth of polycyclic aromatic hydrocarbons in heavy aromatics oil. The catalytic hydrogenation reaction of the tricyclic aromatic hydrocarbon phenanthrene is carried out respectively in a conventional fixed-bed reaction device (as Figure 2 shown), the device for intensifying the hydrogenation depth of polycyclic aromatic hydrocarbons in heavy aromatics oil of Example 1 and Example 2. The catalyst in the catalyst bed is a Pt-Pd / Al2O3 catalyst. The catalyst loading conditions are as follows: Weigh 1.0 g of the Pt-Pd / Al2O3 catalyst precursor with a particle size of 40-60 mesh and load it into the fixed-bed reactor 8 with an inner diameter of 4 mm and a length of 270 mm. Both ends of the catalyst precursor are filled with quartz sand. The catalyst reduction conditions are: hydrogen partial pressure of 1 MPa, hydrogen flow rate of 100 mL / min, heating up to 300 °C at a heating rate of 5 °C / min and holding for 3 h.

[0040] The hydrogenation reaction conditions are: reaction temperature of 180 °C, hydrogen partial pressure of 5 MPa, hydrogen-oil ratio of 900 / 1, and liquid hourly space velocity of 3.33 h -1 .

[0041] Hydrogen and a 5% mass fraction of tricyclic aromatic hydrocarbon phenanthrene / n-decane liquid raw material are respectively in a conventional fixed-bed reaction device ( Figure 2At the inlet, mixing is achieved through a three-way joint with a pipe diameter of 3 mm, and micron-scale mixing is achieved in the CPMM type microchannel mixer of Example 1 and the SIMM type microchannel mixer of Example 2. After mixing by the CPMM type microchannel mixer and the SIMM type microchannel mixer, the scale of each fluid is 0.6 μm and 8 μm respectively. The mixed fluid enters the fixed bed reactor 8 vertically downward. After the feed is stable for 2 h, the product is sampled and analyzed every 1 h.

[0042] The comparison results of the conversion rate and product selectivity of tricyclic aromatic hydrocarbon phenanthrene in three reaction devices are shown in Table 1.

[0043] Table 1 Comparison results of the conversion rate and product selectivity of tricyclic aromatic hydrocarbon phenanthrene in three reaction devices

[0044]

[0045] Under the condition of a very high conversion rate of phenanthrene (the conversion rate of phenanthrene on all three reaction devices is greater than 98%), compared with the conventional fixed bed hydrogenation reaction device, the selectivity of perhydrophenanthrene on the fixed bed reaction devices with pre-positioned CPMM and SIMM type microchannel mixers increases by 1.3% and 0.6% respectively; the selectivity of octahydrophenanthrene increases by 5.8% and 4.5% respectively; the selectivity of tetrahydrophenanthrene decreases by 0.4% and 0.5% respectively; the selectivity of dihydrophenanthrene decreases by 6.7% and 4.6% respectively. The hydrogenation depth of phenanthrene on the fixed bed reactors with pre-positioned CPMM and SIMM type micro mixers is higher than that on the conventional fixed bed reactor.

[0046] Example 4

[0047] A method for a device for enhancing the hydrogenation depth of polycyclic aromatic hydrocarbons in heavy aromatic oil. The catalytic hydrogenation reaction of bicyclic aromatic hydrocarbon naphthalene is carried out respectively in a conventional fixed bed reaction device (as Figure 2 shown), and the devices of the methods for enhancing the hydrogenation depth of polycyclic aromatic hydrocarbons in heavy aromatic oil in Example 1 and Example 2. The catalyst in the catalyst bed, its filling method and reduction conditions are the same as those in Example 3. The gas-liquid mixing method and the scale of each fluid after mixing are the same as those in Example 3. The reaction conditions are: reaction temperature 200 °C, hydrogen partial pressure 5 MPa, hydrogen-oil ratio 900 / 1, liquid hourly space velocity 3.33 h -1 . The liquid raw material is a 5% by mass bicyclic aromatic hydrocarbon naphthalene / n-decane solution. The sampling and analysis conditions of the liquid product are the same as those in Example 3.

[0048] The comparison results of the conversion rate and product selectivity of bicyclic aromatic hydrocarbon naphthalene on three reaction devices are shown in Table 2.

[0049] Table 2 Comparison results of the conversion rate and product selectivity of bicyclic aromatic hydrocarbon naphthalene on three reaction devices

[0050]

[0051] Under the condition of 100% conversion rate of bicyclic aromatic hydrocarbons, compared with the conventional fixed-bed hydrogenation reactor, the fixed-bed hydrogenation reactors with a preposed CPMM type microchannel mixer and a SIMM type microchannel mixer increase the decalin selectivity by 9.0% and 6.8% respectively; and decrease the tetralin selectivity by 9.0% and 6.8% respectively. The hydrogenation depth on the fixed-bed reactors with a preposed CPMM microchannel mixer and a SIMM type microchannel mixer is higher than that on the conventional fixed-bed reactor.

[0052] Example 5

[0053] A method for a device for enhancing the hydrogenation depth of polycyclic aromatic hydrocarbons in heavy aromatic oil. The heavy aromatic oil (provided by Zhejiang Petrochemical Co., Ltd., the contents of total naphthenes, total monocyclic aromatic hydrocarbons, total bicyclic aromatic hydrocarbons and total tricyclic aromatic hydrocarbons in the heavy aromatic raw material are: 0.1%, 46.5%, 28.0% and 25.4% respectively). The catalytic hydrogenation reaction is carried out in a conventional fixed-bed reaction device (as Figure 2 shown), and in the devices of the methods for enhancing the hydrogenation depth of polycyclic aromatic hydrocarbons in heavy aromatic oil in Example 1 and Example 2. The catalyst and reduction conditions are the same as those in Example 3. The gas-liquid mixing method and the scale of each fluid after mixing are the same as those in Example 3. The catalyst loading conditions are as follows: Weigh 1.7 g of 40-60 mesh PtPd / Al2O3 precursor and load it into a constant-temperature reaction tube with an inner diameter of 4 mm and a length of 270 mm. Both ends of the catalyst precursor are filled with quartz sand.

[0054] The hydrogenation reaction conditions are: reaction temperature 300 °C, hydrogen partial pressure 5 MPa, hydrogen-oil ratio 900 / 1, liquid hourly space velocity 1.98 h -1 .

[0055] The comparison results of the conversion rates of total tricyclic aromatic hydrocarbons and total bicyclic aromatic hydrocarbons in heavy aromatic oil in the three reaction devices are shown in Table 3.

[0056] Table 3 Comparison results of the conversion rates of aromatic hydrocarbons in the heavy aromatic oil raw material in the three reaction devices

[0057]

[0058] Under the condition that the total aromatic hydrocarbon conversion rate is higher than 75%, compared with the conventional fixed-bed hydrogenation reactor, the fixed-bed reactors with a preposed CPMM type microchannel mixer and a SIMM type microchannel mixer increase the conversion rate of total tricyclic aromatic hydrocarbons in heavy aromatic oil by 8.2% and 7.9% respectively; and decrease the conversion rate of total bicyclic aromatic hydrocarbons in heavy aromatic oil by 0.9% and 7.5% respectively. The hydrogenation depth of the fixed-bed reactors with a preposed CPMM type microchannel mixer and a SIMM type microchannel mixer is higher than that of the conventional fixed-bed reactor.

[0059] Through the above description, the key device and process technical solutions of the present invention have been clearly disclosed. However, those skilled in the art are well aware that some modifications and improvements can be made to the present invention. Therefore, as long as it does not depart from the spirit of the present invention, any modifications and improvements made to the present invention should be within the scope of the present invention. The scope of the present invention is set forth in the appended claims.

Claims

1. An apparatus for enhancing the hydrogenation depth of polycyclic aromatic hydrocarbons in heavy aromatics oil, which is composed of a hydrogen and heavy aromatics oil metering and control unit (I), a strengthened mixer series fixed bed reactor unit (II) and a gas-liquid separation unit (III). The units are sequentially connected in series through pipelines. It is characterized in that, The enhanced mixer series fixed-bed reactor unit (II) includes an enhanced mixer (6), a short-distance cone tube (7), and a fixed-bed reactor (8) connected in sequence. A multi-segment temperature-controlled electric heating furnace (9) is arranged outside the fixed-bed reactor (8). The enhanced mixer (6) is integrated into the inlet of the fixed-bed reactor (8) through the short-distance cone tube (7). This device is used to achieve continuous micron-scale mixing of gas phase and liquid phase under the conditions that the hydrogen-oil ratio is higher than 860:1 and the conversion rate of polycyclic aromatic hydrocarbons is not less than 70%. The sizes of both ends of the short-distance cone tube (7) match the outlet size of the enhanced mixer (6) and the inlet size of the fixed-bed reactor (8) respectively, and the length of the short-distance cone tube (7) is 3 - 8 cm.

2. The device for deepening the hydrogenation of polycyclic aromatic hydrocarbons in the fortified heavy aromatic oil according to claim 1, characterized in that, The hydrogen and heavy aromatic oil metering and control unit (I) includes a gas feed unit and a liquid feed unit. The gas feed unit includes a gas feed pipe and a pressure reducing valve (1), a pressure gauge (2), a stop valve (3), and a gas mass flowmeter (4) installed on the gas feed pipe. One end of the gas feed pipe is connected to a gas supply source. The liquid feed unit includes a liquid feed pipe and a stop valve (3) and a liquid metering pump (5) arranged on the liquid feed pipe. One end of the liquid feed pipe is connected to a liquid supply source. The other ends of the gas feed pipe and the liquid feed pipe are both connected to the inlet of the enhanced mixer (6).

3. The device for enhancing the hydrogenation depth of polycyclic aromatic hydrocarbons in fortified heavy aromatics oil according to claim 1, wherein Inside the fixed-bed reactor (8), there are a quartz sand bed layer, a catalyst bed layer, and a quartz sand bed layer from top to bottom in sequence.

4. The device for enhancing the hydrogenation depth of polycyclic aromatic hydrocarbons in fortified heavy aromatic oil according to claim 1, wherein The gas-liquid separation unit (III) includes a high-pressure gas-liquid separator (10), a low-pressure gas-liquid separator (11), and a liquid storage tank (12) connected in sequence. The outlet of the fixed-bed reactor (8) is connected to the inlet of the high-pressure gas-liquid separator (10).

5. The device for enhancing the hydrogenation depth of polycyclic aromatic hydrocarbons in fortified heavy aromatic oil according to claim 1, wherein The enhanced mixer (6) is a mixer capable of achieving micron-scale mixing of hydrogen and heavy aromatic oil in two phases under high hydrogen-oil ratio conditions.

6. A method for a device for deepening the hydrogenation of polycyclic aromatic hydrocarbons in the enhanced heavy aromatics oil according to any one of claims 1 to 5, characterized in that, Under the conditions that the hydrogen-oil ratio is higher than 860:1 and the conversion rate of polycyclic aromatic hydrocarbons is not less than 70%, hydrogen and heavy aromatic oil enter the inlet of the enhanced mixer (6) through the hydrogen and heavy aromatic oil metering and control unit (I). A continuous fluid with micron-scale mixing of gas-liquid two phases is formed in the enhanced mixer (6). Then, the continuous fluid with micron-scale mixing of gas-liquid two phases enters the catalyst bed layer of the fixed-bed reactor (8) in a downward manner through the short-distance cone tube (7) to carry out a hydrogenation reaction. The reacted fluid flows out from the outlet of the fixed-bed reactor (8) and enters the inlet of the high-pressure gas-liquid separator (10) to carry out gas-liquid two-phase separation in the gas-liquid separation unit (III).

7. The method according to claim 6, characterized in that, The micron-scale mixing means that the mixing scale of gas-liquid two phases ≤ 10 μm.

8. The method according to claim 6, wherein The mixing conditions in the enhanced mixer (6) are: the temperature is -30°C to 300°C, and the mixing pressure is the same as that of the fixed-bed hydrogenation reactor.

9. The method according to claim 6, wherein The conditions of the hydrogenation reaction are as follows: pressure of 1 to 20 MPa, liquid hourly space velocity of 0.1 to 5.0 h -1 , reaction temperature of 140°C to 300°C; the catalyst for the hydrogenation reaction is a highly active hydrogenation catalyst, selected from one of Pt / Al2O3, Pd / Al2O3, Pt-Pd / Al2O3, and highly active Ni-based catalysts.

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