A catalytic distillation device and method for producing clean gasoline

Abstract

The present invention discloses a catalytic distillation desulfurization device and method for producing clean gasoline. Gasoline is first separated, and the heavy fraction enters the catalytic distillation tower, and is subjected to hydrodesulfurization reaction with the upward hydrogen in multiple catalyst beds in stages. The hydrogen sulfide generated by the hydrodesulfurization and the unreacted gas phase feed are discharged from the top of the catalytic distillation tower through an independent gas phase channel, and the gasoline heavy fraction is obtained at the bottom of the tower. The method of the present invention allows the light components and hydrogen sulfide to quickly leave the system and no longer participate in the reaction, effectively preventing hydrogen sulfide from further combining with olefins to form mercaptans; at the same time, the reaction products after desulfurization quickly leave the catalytic distillation tower, which is conducive to promoting the reaction to the right, and improving the reaction rate and liquid yield.

Description

Technical Field

[0001] The invention belongs to the field of gasoline production by hydrogenation refining, and more specifically, relates to a catalytic distillation device and method for producing clean gasoline. Background Art

[0002] With the rapid development of the automobile industry, automobile exhaust has become more and more polluting to the environment. Countries have also formulated increasingly stringent standards for automobile fuel to reduce the emission of harmful substances, among which the restrictions on the sulfur and olefin content in automobile gasoline are even more stringent. However, about 80% of domestic automobile gasoline is catalytic cracking gasoline, which has an olefin volume content of up to 30%~45% and a high sulfur content. Therefore, how to achieve a high desulfurization rate, moderately reduce the olefin content, and minimize the octane number loss is an urgent problem to be solved.

[0003] The olefin content is high and the sulfur content is low in the light fraction of catalytic cracking gasoline, while the sulfur content is high and the olefin content is low in the heavy fraction. The sulfur in the light fraction is mainly mercaptan, while the sulfur in the heavy fraction is mainly thiophene and benzothiophene. Based on this characteristic, many gasoline selective hydrogenation technologies usually cut the catalytic gasoline fraction into two fractions, light and heavy, or three fractions, light, medium and heavy, and process them according to the characteristics of different fractions.

[0004] The Prime-G+ technology developed by IFP in France first selectively hydrogenates the catalytic cracking whole-fraction oil, and then separates the hydrogenated products into light components and heavy components. The light components can be directly used as gasoline blending components or as etherification and alkylation feeds, and the heavy components enter the hydrogenation reactor and undergo hydrodesulfurization reaction under a dual catalyst system. This method has good stability and high liquid yield, but the octane number loss is large. The hydrogen sulfide produced by selective hydrodesulfurization cannot be discharged from the reactor in time, and will further react with olefins to form mercaptans. The mercaptan content in the product is high, and further desulfurization is required.

[0005] The catalytic distillation desulfurization process disclosed in US5597476 includes two catalytic distillation towers. In the first tower, the mercaptans in the light gasoline fraction react with diolefins to generate high-boiling-point sulfides that enter the heavy fraction, and a light gasoline with a low sulfur content is obtained from the top of the tower; the heavy fraction enters the second catalytic distillation tower for hydrodesulfurization. This method is suitable for raw materials with a low olefin content. When used to process gasoline raw materials with a high olefin content, the octane number loss is large. In addition, the desulfurization reaction and distillation separation in the catalytic distillation tower are carried out in stages, and the hydrogen sulfide produced by hydrodesulfurization cannot be discharged from the reactor in time. Summary of the invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a catalytic distillation device and method for producing clean gasoline, so as to overcome the problem that the desulfurization reaction and distillation separation in the catalytic distillation tower are carried out separately in the prior art, and is suitable for catalytic cracking gasoline raw materials with high olefin content. While improving the desulfurization rate, the olefin content is moderately reduced, and the octane number loss is small.

[0007] The first aspect of the present invention is to provide a catalytic distillation device for producing clean gasoline. The catalytic distillation device for producing clean gasoline of the present invention comprises:

[0008] A first-stage catalytic distillation tower, which is provided with: a rectifying section, an upper catalyst bed, a separation section, and a lower catalyst bed in order from top to bottom; the first-stage catalytic distillation tower is used to receive gasoline raw material as liquid feed and separate it into a light fraction and a heavy fraction; the light fraction and hydrogen pass upward through the upper catalyst bed and the rectifying section to carry out diene hydrogenation, sulfide reaction and trans-olefin isomerization reaction; the sulfide product and the heavy fraction pass downward through the lower catalyst bed to contact and react with the hydrogen entering from the lower part of the first-stage catalytic distillation tower;

[0009] The two-stage catalytic distillation tower is used to receive the heavy gasoline fraction obtained from the first-stage distillation tower as liquid feed, and the liquid feed flows through each catalyst bed in the distillation tower from top to bottom; the preheated hydrogen enters each catalyst bed from the bottom to top evenly from the bottom of each catalyst bed; the liquid feed and hydrogen undergo hydrodesulfurization reaction on the hydrodesulfurization catalyst arranged in the distillation tower; the hydrogen sulfide generated by hydrodesulfurization and the unreacted gas feed are discharged from the top of the catalytic distillation tower through an independent gas phase channel, and the liquid product obtained by hydrorefining is discharged from the bottom of the catalytic distillation tower.

[0010] Furthermore, the device also includes a gas circulation unit, which is used to selectively concentrate the gas obtained from the second-stage catalytic distillation tower and circulate it back to the first-stage catalytic distillation tower and the second-stage catalytic distillation tower.

[0011] Furthermore, the two-stage catalytic distillation tower comprises at least one catalytic reaction zone, and the catalytic reaction zone is a 2-n-layer tower plate structure, each tower plate is loaded with a catalyst bed, wherein n is an integer greater than 2; an inclined partition is arranged on the top of each catalyst bed, preferably an umbrella-shaped partition; and a gas phase channel is arranged through each catalyst bed and the inclined partition.

[0012] Furthermore, in the one-stage catalytic distillation tower, based on the height of the one-stage catalytic distillation tower, the height ratios of the rectification section, the upper catalyst bed, the separation section and the lower catalyst bed are: 5%~20%: 40~60%: 10%~30%: 5%~20%.

[0013] Furthermore, a separation section arranged in a catalytic distillation tower may or may not be provided with fillers or plates, and is used to pre-separate the feed under the action of hydrogen stripping, whereby the light fraction is carried upward into the upper catalyst bed, and the heavy fraction is carried downward into the lower catalyst bed.

[0014] Furthermore, in a first stage catalytic distillation tower, a hydrorefining catalyst is placed in the upper catalyst bed and the lower catalyst bed. The hydrorefining catalyst is generally based on alumina or silicon-containing alumina as a carrier, and has metals of Group VIB and Group VIII as active components, such as one, two or more selected from W, Mo, Co, and Ni.

[0015] Furthermore, a rectifying section provided in a catalytic distillation tower may be provided with fillers or tower plates, or may be loaded with a hydrotreating catalyst. The fillers or tower plates are all conventional in the art, such as the fillers may be selected from one or more random packings such as ball rings, Raschig rings, rectangular saddle rings, saddle-shaped, open-hole ring types, semi-rings, step rings, double arcs, Haier rings, conjugated rings, flat rings, and wreaths, and the fillers may also be selected from metal or ceramic corrugated packings. The tower plate may be one or more of the tower plates with downcomers such as bubble plates, sieve plates, float valve plates, mesh plates, tongue-shaped plates, guide sieve plates, and multi-downcomer tower plates, and may also be tower plates without downcomers such as flow-through sieve plates and flow-through corrugated plates. High-efficiency tower plates such as guide float valves and sieve plate towers are preferred.

[0016] Furthermore, the two-stage catalytic distillation tower further comprises a liquid-phase feed subunit, which is arranged above the inclined partition of the topmost catalyst bed, and the liquid-phase feed is guided to the catalyst bed through the inclined partition.

[0017] Furthermore, an annular downcomer is provided at the end of the inclined partition, and the bottom of the annular downcomer is spaced a distance from the bottom of the catalyst bed, so that the liquid feed enters the catalyst bed in a radial direction.

[0018] Furthermore, the two-stage catalytic distillation tower further comprises a gas-phase feed subunit, which is arranged between the catalyst bed layer of the upper layer and the inclined partition plate of the lower layer. The gas-phase feed enters the catalyst bed layer of the upper layer upward.

[0019] Furthermore, the lower end of the gas phase channel passing through the upper catalyst bed is connected to the inclined partition on the next catalyst bed. This design makes the gas phase channel relatively isolated from the gas phase feed subunit, and the gas phase product generated after the gas phase feed and the liquid phase feed react in the catalyst bed directly enters the gas phase channel.

[0020] Furthermore, in the second-stage catalytic distillation tower, the catalyst bed is provided with: an overflow weir, which is arranged on the side close to the gas phase channel; and a liquid sealing baffle, which is arranged on the upper part of the overflow weir to isolate the gas phase feed from the gas phase product.

[0021] Furthermore, the liquid seal baffle includes: a horizontal portion, which is an annular flat plate and is located above the overflow weir; a vertical portion, which is cylindrical and is integrally formed with the horizontal portion, and the lower end of the vertical portion is spaced a distance from the bottom of the catalyst bed.

[0022] Furthermore, the liquid-phase feed subunit further includes: a liquid-phase feed pipe, which extends in the radial direction of the catalyst bed; a liquid-phase distribution pipe, which is annular and intersects orthogonally or tangentially with the liquid-phase feed pipe, and the tube wall of the liquid-phase distribution pipe is provided with a plurality of channels for evenly distributing the liquid-phase feed to all directions of the annular downcomer.

[0023] Furthermore, the gas-phase feed subunit further includes: a gas-phase feed pipe, which extends in the radial direction of the catalyst bed; a gas-phase distribution pipe, which is in a ring shape or a multi-layer concentric ring shape, and the gas-phase distribution pipe intersects the gas-phase feed pipe orthogonally or tangentially, and a plurality of channels are provided on the wall surface of the gas-phase distribution pipe for evenly distributing the gas-phase feed to all directions at the bottom of the catalyst bed.

[0024] Furthermore, the gas phase feeding subunit may also include: a gas phase distribution plate, which is located at the bottom of the catalyst bed and is in the shape of a plate as a whole, and a plurality of holes are evenly and densely distributed on the gas phase distribution plate.

[0025] Furthermore, the gas phase channel is located in the middle of the catalytic reaction unit and passes through all catalyst beds from bottom to top.

[0026] Furthermore, in the second-stage catalytic distillation tower, the height of the catalyst bed can be set to 10 mm to 1000 mm depending on the reaction system.

[0027] Furthermore, the upper edge of the overflow weir may be 10 to 100 mm higher than the upper surface of the catalyst in the bed.

[0028] Furthermore, the gas phase distribution pipe may be arranged below the catalyst bed or inside the catalyst bed.

[0029] The second aspect of the present invention is to provide a catalytic distillation method for producing clean gasoline. Specifically, a catalytic distillation method for producing clean gasoline comprises the following steps:

[0030] (1) After being heated, the gasoline feedstock enters the middle separation section of a catalytic distillation tower, where the light fraction is carried away by the hydrogen flowing upward from the bottom of the tower and enters the upper catalyst bed layer, where diene hydrogenation, sulfide reaction and trans-olefin isomerization reaction are carried out under the action of the hydrotreating catalyst; the light gasoline after hydrotreating is extracted from the distillation section; the heavy fraction and the sulfide compounds generated by the reaction of the upper catalyst bed layer enter the lower catalyst bed layer downward, react with the hydrogen entering from the bottom, and the hydrogen sulfide generated by the reaction flows upward from the top of the tower under the carry-over of the hydrogen, while the heavy gasoline fraction flows downward;

[0031] (2) The heavy gasoline fraction obtained in step (1) enters a second-stage catalytic distillation tower, descends in the tower and sequentially enters multiple catalyst beds, where it contacts the hydrogen entering the catalyst beds to undergo a hydrodesulfurization reaction; the gaseous product obtained by the reaction of each catalyst bed enters a gas phase channel, flows upward out of the second-stage catalytic distillation tower in the gas phase channel; the liquid phase stream obtained by the reaction of each catalyst bed sequentially enters the next catalyst bed to undergo a reaction, and the liquid stream finally flows downward out of the second-stage catalytic distillation tower.

[0032] Furthermore, in step (1), after the gas phase at the top of the tower is cooled, the liquid phase is fully refluxed, and the non-condensable gas is desulfurized to obtain hydrogen-rich gas.

[0033] Furthermore, after the gas phase at the top of the second-stage catalytic distillation tower is cooled, hydrogen-rich gas can be obtained after the non-condensable gas is desulfurized, and part of the condensate is refluxed, and the remaining part enters the stabilization tower together with the liquid phase flow flowing out of the bottom of the tower. After the non-condensable gas contained in the stabilization tower is removed, the heavy gasoline product is obtained from the bottom of the stabilization tower.

[0034] Furthermore, the hydrogen-rich gas obtained from the top of the first-stage catalytic distillation tower and the second-stage catalytic distillation tower is recycled.

[0035] Furthermore, the gasoline feedstock is selected from one or a mixture of catalytic cracking gasoline, catalytic pyrolysis gasoline, coking gasoline and thermal cracking gasoline.

[0036] Furthermore, the operating conditions of the first stage catalytic distillation tower in step (1) are as follows: reaction temperature of 100°C to 260°C, reaction pressure of 0.5MPa to 3.0MPa, hydrogen to oil volume ratio of 200 to 800, liquid hourly volume space velocity of 1.0h -1 ~10.0h -1 The extraction temperature of the distillation section is 60°C to 120°C, preferably 60 to 90°C.

[0037] Furthermore, in step (2), the number of catalyst beds in the catalytic distillation tower is n, and all catalyst beds may be loaded with hydrodesulfurization catalyst; preferably, the upper catalyst bed may be loaded with hydrodesulfurization catalyst, and the lower catalyst bed [1] may be loaded with hydroreforming catalyst. The ratio of the number of layers of hydrodesulfurization catalyst to hydroreforming catalyst is preferably 1:1 to n-1:1. The hydrodesulfurization catalyst generally comprises an active component and a carrier, wherein the carrier component comprises aluminum oxide, silicon oxide or a mixture of aluminum oxide and silicon oxide; the active component is one or more of Group VIB and Group VIII metals, wherein Group VIB metals are generally Mo and / or W, and Group VIII metals are generally Co and / or Ni. The hydroreforming catalyst is generally a carrier of ZSM-5, Beta, SAPO molecular sieve or a mixture thereof, and an active component of a metal of Group VIB and Group VIIIB, such as one, two or more selected from W, Mo, Co and Ni.

[0038] The hydrotreating catalyst, hydrodesulfurization catalyst and hydro-upgrading catalyst may be in any conventional catalyst shape, preferably a porous catalyst, a shaped catalyst and / or a honeycomb catalyst. The porous catalyst has a pore size of 1 to 50 mm, preferably 4 to 20 mm; the average particle diameter of the shaped catalyst is 2 to 50 mm, preferably 4 to 30 mm; the pore diameter or pore side length of the honeycomb catalyst is 1 to 50 mm, preferably 3 to 15 mm; the catalyst bed void ratio is recommended to be 15% to 85%, preferably 20% to 75%.

[0039] Furthermore, the operating conditions of the second-stage catalytic distillation tower in step (3) are: reaction temperature of 220°C to 400°C, reaction pressure of 1.0MPa to 2.5MPa, hydrogen-to-oil volume ratio of 50 to 800, liquid hourly volume space velocity of 0.5h -1 ~8.0h -1 .

[0040] In the above technical solution, the gas phase product of the two-stage catalytic distillation tower does not enter the adjacent catalyst bed, but directly enters the gas phase channel in the middle of the reactor, and the gas phase channel is in a relatively isolated state from the gas phase feed subunit.

[0041] In the above technical solution, the heavy gasoline fraction obtained in step (1) and the generated sulfide compounds enter the first catalyst bed from a distributor arranged above the uppermost catalyst bed in the two-stage catalytic distillation tower, and then enter each catalyst bed layer by layer from top to bottom through the liquid-phase feed internal components arranged in the reactor.

[0042] Compared with the prior art, the advantages of the present invention are:

[0043] 1. By setting a separation section in the first stage catalytic distillation tower, the initial separation of light and heavy fractions is achieved. After the light fraction gasoline is hydrorefined, it is directly extracted from the distillation section by the side line. There is no need to set up a fractionation tower between the first and second stage catalytic distillation towers, which simplifies the process flow; the dienes in the heavy fraction gasoline undergo a hydrogenation saturation reaction in the lower stage catalyst bed, so it will not poison the hydrodesulfurization catalyst in the second stage catalytic distillation tower, extending the life of the hydrodesulfurization catalyst. In addition, the heavy fraction gasoline also undergoes a preliminary desulfurization reaction in the lower stage catalyst bed, and the hydrogen sulfide produced by the reaction can flow upward from the top of the tower under the carrier of hydrogen, avoiding integration into the heavy components to generate mercaptan.

[0044] 2. The two-stage catalytic distillation tower of the present invention adopts a layered tower component and a gas phase channel design, which realizes a high degree of coupling between the catalytic reaction and the distillation separation. The hydrogen sulfide generated by the desulfurization reaction can immediately leave the reaction zone from the gas phase channel, which overcomes the problem of the desulfurization reaction and the distillation separation being carried out in stages in the catalytic distillation tower in the prior art, and can effectively prevent hydrogen sulfide from further combining with olefins to form mercaptans, thereby preventing the mercaptan content of gasoline after desulfurization from exceeding the standard.

[0045] 3. The device of the present invention can make gasoline react in a cascade reaction in the reactor, control the reaction depth of different fractions in the reactor, and effectively inhibit the occurrence of side reactions such as olefin polymerization and aromatic alkylation, thereby greatly improving the desulfurization rate while moderately reducing the olefin content and minimizing the octane number loss; at the same time, the reaction products quickly leave the catalytic distillation tower, which is conducive to promoting the reaction to the right, improving the reaction rate and liquid yield, and reducing the heat load of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic diagram of the principle flow chart of the present invention.

[0047] Figure 2 It is a structural schematic diagram of the catalytic reaction distillation tower of the present invention.

[0048] Figure 3 It is a top view of the liquid phase distribution pipe in the catalytic reaction distillation tower of the present invention.

[0049] Figure 4 It is a top view of the gas phase feed pipe and the gas phase distribution pipe in the catalytic reaction distillation tower of the present invention (showing the situation where the gas phase feed pipe and the annular gas phase distribution pipe are orthogonally arranged).

[0050] Figure 5 It is another top view of the gas phase feed pipe and the gas phase distribution pipe in the catalytic reaction distillation tower of the present invention (showing the situation where the gas phase feed pipe and the annular gas phase distribution pipe are tangentially intersected).

[0051] Figure 6 It is a top view of the gas phase distribution pipe of the present invention which adopts a concentric double-ring distribution pipe.

[0052] Figure 7 It is a top view of the gas phase distribution plate in the catalytic reaction distillation tower of the present invention.

[0053] Figure 8 It is a top view of the catalyst support plate in the catalytic reaction distillation tower of the present invention.

[0054] Fig. 9 It is a schematic diagram of the top structure of a liquid distribution assembly according to one embodiment of the present invention.

[0055] Fig.10 It is a schematic diagram of the top view and side view of the structure of a liquid distribution assembly according to another embodiment of the present invention.

[0056] Fig.11 3 is a schematic diagram of a top view of the structure of a first overflow ring according to an embodiment of the present invention.

[0057] Fig.12 yes Fig.10 Schematic diagram of the three-dimensional structure of the first overflow ring.

[0058] Description of main reference numerals:

[0059] 1-two-stage catalytic distillation tower, 2-one-stage catalytic distillation tower, 3-heating furnace, 4, 6-condenser, 5, 7-reflux tank, 8-stabilization tower, L1-gasoline, G1-hydrogen, L2-heavy gasoline fraction, G2-first-stage catalytic distillation tower top gas phase, G3-first-stage catalytic distillation tower top non-condensable gas, L3-light gasoline product, G4-catalytic distillation gas phase logistics, L4-two-stage catalytic distillation liquid logistics, G5-second-stage catalytic distillation tower top non-condensable gas, L6-heavy gasoline product, G6-stabilization tower top non-condensable gas.

[0060] 10-solid catalyst, 11-umbrella-shaped inclined partition, 12-outer downcomer, 13-gas phase channel, 14-overflow weir, 15-downcomer folding plate, 16-liquid receiving tray, 17-liquid sealing baffle, 18-inner downcomer, 19-catalyst support plate, 191-grid;

[0061] 21-liquid phase feed pipe, 22-liquid phase distribution pipe, 220-liquid phase distribution pipe body, 221-liquid phase channel;

[0062] 31-gas phase feed pipe, 32-gas phase distribution pipe, 320-gas phase distribution pipe body, 321-gas phase channel, 33-gas phase distribution plate, 331-hole; 34-liquid phase product;

[0063] Sawtooth portion 14-1, guide groove 14-2. DETAILED DESCRIPTION

[0064] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific implementation modes.

[0065] Figure 1 The figure shows a process flow diagram of gasoline catalytic distillation desulfurization according to the present invention. Figure 1 As shown, gasoline L1 is heated by a heating furnace 3 and then enters a separation section of a first-stage catalytic distillation tower 2 for pre-fractionation, wherein the light fraction is carried away by the hydrogen G1 flowing upward from the bottom and enters the upper catalyst bed upward, and undergoes diene hydrogenation, sulfide reaction and trans-olefin isomerization reaction under the action of a hydrotreating catalyst; the light gasoline product L3 after hydrotreating is extracted from the distillation section; the heavy fraction reacts with the upper catalyst bed to generate sulfide compounds and enters the lower catalyst bed downward, and the hydrogen sulfide produced by the reaction flows upward from the top of the tower under the carry of hydrogen, and the heavy gasoline fraction L2 flows downward; after the gas phase G2 at the top of the first-stage catalytic distillation tower is cooled, the liquid phase is fully refluxed, and the non-condensable gas G3 at the top of the first-stage catalytic distillation tower is dehydrogenated to obtain a hydrogen-rich gas.

[0066] The heavy gasoline fraction L2 enters the liquid phase feed pipe 21 of the second-stage catalytic distillation tower 1, and flows downward along the catalyst bed after being evenly distributed by the liquid phase distribution pipe 22. The heavy gasoline fraction L2 contacts and reacts with the hydrogen entering the catalyst bed from the gas phase feed pipe 31 upward; the gas phase product obtained by the reaction of each catalyst bed directly enters the gas phase channel 13, and the liquid phase product obtained by the reaction of each catalyst bed sequentially enters the next catalyst bed for reaction, and the final second-stage catalytic distillation liquid phase flow L4 flows downward out of the catalytic distillation tower 1 and enters the stabilization tower 8. The second-stage catalytic distillation gas phase flow G4 from the gas phase channel 13 flows out from the top of the second-stage catalytic distillation tower 1 and enters the condenser 6. After condensation, the material enters the reflux tank 7. The non-condensable gas G5 at the top of the second-stage catalytic distillation tower can be recycled as hydrogen-rich gas after desulfurization of hydrogen. The condensed liquid part flows back to the second-stage catalytic distillation tower 1, and the remaining condensed liquid L5 at the top of the second-stage catalytic distillation tower enters the stabilization tower 8. After the non-condensable gas G6 at the top of the stabilization tower is removed by the stabilization tower 8, the heavy gasoline product L6 is obtained from the bottom of the stabilization tower. The light gasoline product L3 and the heavy gasoline product L6 are mixed to obtain a clean gasoline product.

[0067] Furthermore, the liquid-phase feed internal components in the reactor described in the above technical solution include a liquid-phase feed pipe 21, an umbrella-shaped baffle 11, and an annular downcomer 12 is provided at the end of the umbrella-shaped baffle 11. The bottom of the downcomer is spaced a distance from the bottom of the catalyst bed, so that the liquid-phase feed enters the catalyst bed in a radial direction.

[0068] Further, if Figure 2As shown, the height of each catalyst bed in the reaction distillation tower 1 can be the same or different, depending on the different chemical reaction systems. The catalyst bed is fixed with a screen to keep the bed relatively stable. The bed height is set to 10 mm to 1000 mm. The catalyst bed is provided with: an overflow weir 14, which is arranged on the side 13 close to the gas phase channel; a liquid sealing baffle 17, which is arranged on the upper part of the overflow weir to isolate the gas phase feed from the gas phase product.

[0069] Furthermore, in the above technical solution, the liquid seal baffle 17 includes: a horizontal portion, which is annular and flat and located above the overflow weir 14; a vertical portion, which is cylindrical, and the vertical portion is integrally formed with the horizontal portion, and the lower end of the vertical portion is spaced a distance from the bottom of the catalyst bed. The height of the overflow weir 14 is higher than the upper plane of the catalyst bed, preferably 10 to 100 mm higher.

[0070] A gas-phase feed subunit is provided in each catalyst bed of the catalytic reaction zone, which is specifically provided between the catalyst bed of the upper layer and the umbrella-shaped partition 11 of the lower layer, and the gas-phase feed of each layer enters the catalyst bed upward. After the gas-liquid phase feed and the solid catalyst are fully reacted in the catalyst bed, the gas-phase product of each layer is guided to the gas-phase channel 13 along the lower part of the umbrella-shaped partition 11. The gas-phase channel 13 is in a relatively isolated state from the gas-phase feed subunit, that is, the gas-phase product generated after the gas-phase feed and the liquid-phase feed react in the catalyst bed directly enters the gas-phase channel 13. Preferably, but not restrictively, the gas-phase channel is located in the middle of the reaction distillation tower 1, and passes through all the catalyst beds from bottom to top.

[0071] Further Figure 2 , 4 As shown in FIG. 6 , the gas phase feed subunit includes a gas phase feed pipe 31 and a gas phase distribution pipe 32. The gas phase feed pipe 31 extends in the radial direction of the reaction distillation tower 1. The gas phase distribution pipe 32 is annular (see FIG. Figure 4 , 5 ) or multiple layers of concentric rings (see Figure 6 The gas phase feed pipe 31 is orthogonal to the gas phase distribution pipe body 320 of the gas phase distribution pipe 32 (see Figure 4 ) or tangential intersection (see Figure 5 ), a plurality of gas phase channels 321 are provided on the wall of the gas phase distribution pipe 32, which are used to evenly distribute the gas phase feed to all directions at the bottom of the catalyst bed. Preferably, but not limiting, the gas phase distribution pipe 32 can be arranged below the catalyst bed, or can be arranged inside the catalyst bed. Figure 7As shown, the gas-phase feed subunit further includes a gas-phase distribution plate 33, which is located at the bottom of the catalyst bed and is in the shape of a plate as a whole. The gas-phase distribution plate is uniformly and densely distributed with a plurality of holes 331. The gas-phase feed enters the reaction distillation tower 1 through the gas-phase feed pipes 31 of each layer, is distributed into the reaction distillation tower 1 through the annular gas-phase distribution pipe 32, and enters the catalyst bed upward through the gas-phase distribution plate 33 at the lower part of the catalyst support plate 19. The gas-phase feed pipe 31 enters the reaction distillation tower 1 in a radial direction, and intersects orthogonally or tangentially with the annular gas-phase distribution pipe 32. The annular gas-phase distribution pipe 32 is located below the catalyst bed. The annular diameter of the annular gas-phase distribution pipe 32 is smaller than the outer ring diameter of the catalyst bed, and the inner diameter is larger than the inner ring diameter of the catalyst bed. The several gas-phase channels 321 on the wall of the annular gas-phase distribution pipe 32 facilitate the uniform distribution of gas at various positions of the gas-phase distribution plate 33. The catalyst support plate 19 mainly supports the catalyst bed to ensure that the catalyst bed remains stable in the axial direction of the reaction distillation tower. The function of the gas phase distribution plate 33 is to ensure uniform distribution of the gas phase feed, while trying to avoid direct leakage of the liquid phase feed on the catalyst bed (using the gas phase distribution plate 33 of the present invention, the liquid leakage is less than 15%). When more than one concentric annular gas phase distribution pipe 32 with different diameters is arranged on the same plane, the distribution of the gas phase feed can be more uniform. Figure 2 In the embodiment of the present invention, the annular gas phase distribution pipe 32 is arranged below the catalyst bed layer. When the annular gas phase distribution pipe 32 is installed in the catalyst bed layer, the catalyst support plate 19 can Figure 8 The grid 191 is changed into a support plate, and the gas phase distribution plate 33 is cancelled.

[0072] Example 1

[0073] The above-mentioned device and process of the present invention are used to carry out catalytic distillation treatment on the raw material catalytic cracking gasoline. The properties of the raw material catalytic cracking oil are shown in Table 1.

[0074] In a catalytic distillation tower, from top to bottom, the rectification section, the upper catalyst bed, the separation section and the lower catalyst bed occupy 13%: 55%: 15%: 17% of the height of the catalytic distillation tower respectively. After being heated, gasoline enters the separation section of a catalytic distillation tower, wherein the light fraction obtained in the separation section is carried away by the hydrogen flowing upward from the bottom of the tower and enters the upper catalyst bed upward, and is subjected to diene hydrogenation, sulfide reaction and trans-olefin isomerization reaction under the action of the hydrofining catalyst FH-40A (trade name, produced by Sinopec Dalian Petrochemical Research Institute); the light gasoline after hydrofining is extracted from the distillation section at a temperature of 80°C; the heavy fraction reacts with the upper catalyst bed to generate sulfide compounds and enters the lower catalyst bed FH-40C (trade name, produced by Sinopec Dalian Petrochemical Research Institute) downward, hydrogen enters the lower part of the catalytic distillation tower, and the hydrogen sulfide generated by the hydrodesulfurization reaction flows upward from the top of the tower under the carry of hydrogen, and the heavy gasoline fraction flows downward; after the gas phase at the top of the tower is cooled, the liquid phase is fully refluxed, and the non-condensable gas can be desulfurized to obtain hydrogen-rich gas to continue to reflux for use.

[0075] The two-stage catalytic distillation tower is equipped with five trays. The upper parts of the first to fourth trays are filled with hydrodesulfurization catalyst ME-1, and the fifth tray is filled with hydro-reforming catalyst FDW-3. All catalysts used are produced by Dalian Petrochemical Research Institute of Sinopec. The single-layer catalyst bed height is 500mm, and the overflow weir height is 80mm. The obtained heavy gasoline fraction enters the two-stage catalytic distillation tower, and enters multiple catalyst beds in turn while descending in the tower, and contacts and reacts with the hydrogen entering the catalyst bed upward; the gas phase product obtained by the reaction of each catalyst bed enters the gas phase channel, and flows out of the catalytic distillation tower upward in the gas phase channel; the liquid phase product obtained by the reaction of each catalyst bed enters the next catalyst bed in turn to react, and the final liquid product flows out of the catalytic distillation tower downward.

[0076] The gas phase flow from the gas phase channel is cooled and divided into gas phase and condensate. After the gas phase is desulfurized, it is used as hydrogen-rich gas for continuous reflux, and part of the condensate is refluxed and part enters the stabilization tower. The liquid flow from the bottom of the catalytic distillation tower also enters the stabilization tower. After the non-condensable gas contained in the stabilization tower is removed, the heavy gasoline product is obtained from the bottom of the stabilization tower. The light gasoline product and the heavy gasoline product are mixed to obtain a clean gasoline product.

[0077] The reaction process conditions are shown in Table 2, and the properties of the clean gasoline product are shown in Table 3.

[0078] Example 2

[0079] The difference between this embodiment and embodiment 1 is that 8 catalyst beds are arranged in the two-stage catalytic distillation tower, the upper part of the first to seventh layers of the tower plate is filled with hydrodesulfurization catalyst ME-1, the eighth layer is filled with hydroreforming catalyst FDW-3, the single-layer catalyst bed height is 300 mm, and the overflow weir height is 40 mm. The reaction process conditions are shown in Table 2, and the properties of the clean gasoline product are shown in Table 3. The other conditions are the same as those in embodiment 1.

[0080] Example 3

[0081] The difference between this embodiment and embodiment 1 is that the catalytic reaction distillation tower is provided with 10 catalyst beds, the upper part of the first to eighth layers of the tower plate is filled with hydrodesulfurization catalyst ME-1, the ninth and tenth layers are filled with hydroreforming catalyst FDW-3, the single-layer catalyst bed height is 200 mm, and the overflow weir height is 20 mm. The reaction process conditions are shown in Table 2, and the properties of the clean gasoline product are shown in Table 3. The remaining conditions are the same as those in embodiment 1.

[0082] Embodiment 4-5

[0083] The same as Example 1, the only difference is that the reaction conditions are changed. The specific reaction process conditions are shown in Table 2, and the properties of the clean gasoline product are shown in Table 3.

[0084] Comparative Example 1

[0085] The second-stage catalytic distillation tower adopts the CDHDS tower in the industrialized CDHydro / CDHDS selective hydrodesulfurization technology. There are 5 catalyst modules in the CDHDS tower. The first to fourth layers of the tower plates are loaded with hydrodesulfurization catalyst ME-1, and the fifth layer is loaded with hydroreforming catalyst FDW-3. The catalysts used are all produced by Sinopec Dalian Petrochemical Research Institute, and the single-layer catalyst bed height is 500mm. The rest of the process flow and process conditions are the same as in Example 1. The properties of the clean gasoline product are shown in Table 3.

[0086] Comparative Example 2

[0087] The industrialized CDHydro / CDHDS selective hydrodesulfurization process technology is adopted, that is, the first stage catalytic distillation tower adopts the CDHydro tower, and the second stage catalytic distillation tower adopts the CDHDS tower. The gasoline is preheated and enters the catalyst bed from the 12th layer of the CDHydro tower (41 layers in total from top to bottom), and the catalyst bed is loaded with the hydrofining catalyst FH-40A. Hydrogen enters from the 21st plate. Light gasoline is extracted from the 6th layer of the CDHydro tower. After cooling, the gas phase at the top of the tower is desulfurized and recycled, and the liquid phase is completely refluxed. The lower end of the feed inlet is a separation plate, which is not loaded with catalyst. The heavy gasoline and the sulfide generated by the reaction flow to the bottom of the CDHydro tower, and after being extracted from the bottom of the tower, they enter the CDHDS tower with 5-stage catalyst modules. In the CDHDS tower, the upper part of the 1st to 4th tower plates is loaded with hydrodesulfurization catalyst ME-1, and the 5th layer is loaded with hydroreforming catalyst FDW-3. The catalysts used are all produced by Dalian Petrochemical Research Institute of Sinopec. The single-layer catalyst bed height is 500mm and the overflow weir height is 80mm. The rest of the process flow and process conditions are the same as those in Example 1. The properties of the clean gasoline product are shown in Table 3.

[0088] Table 1 Main properties of catalytic cracking gasoline

[0089]

[0090] Table 2 Example process conditions

[0091]

[0092] Table 3 Clean gasoline product properties

[0093]

[0094] From the results in Table 3, it can be seen that the method of the present invention can produce clean gasoline or clean gasoline blending components, with an olefin volume fraction of no more than 15%, a sulfur mass fraction of less than 10 ppm, an antiknock index loss of less than 1.5, and a low mercaptan content. However, the total sulfur content of Comparative Examples 1 and 2 is greater than 10 ppm, and the mercaptan content exceeds the standard.

Claims

1. A catalytic distillation unit for producing clean gasoline, It is characterized in that include: A catalytic distillation tower, which is provided with a rectification section, an upper catalyst bed, a separation section, and a lower catalyst bed from top to bottom; The first stage catalytic distillation tower is used to receive gasoline raw materials as liquid feed and divide them into light fractions and heavy fractions; the light fractions and hydrogen pass upward through the upper catalyst bed and the rectifying section to carry out diene hydrogenation, sulfide reaction and trans-olefin isomerization reaction; the sulfide product and the heavy fraction pass downward through the lower catalyst bed to contact and react with the hydrogen entering from the lower part of the first stage catalytic distillation tower, and the heavy gasoline fraction produced by the reaction flows downward out of the first stage catalytic distillation tower; The second-stage catalytic distillation tower is used to receive the heavy gasoline fraction obtained by the first-stage catalytic distillation tower as a liquid feed, the liquid feed flows from top to bottom through each catalyst bed in the second-stage catalytic distillation tower, and the preheated hydrogen enters each catalyst bed from the bottom to top uniformly from the bottom of each catalyst bed; the liquid feed and hydrogen undergo a hydrodesulfurization reaction on a hydrodesulfurization catalyst arranged in the second-stage catalytic distillation tower; the hydrogen sulfide generated by the hydrodesulfurization and the unreacted gaseous feed are discharged from the top of the second-stage catalytic distillation tower through an independent gas phase channel, and the liquid product obtained by the second-stage catalytic distillation tower is discharged from the bottom of the second-stage catalytic distillation tower; The two-stage catalytic distillation tower comprises at least one catalytic reaction zone, the catalytic reaction zone is a 2-n-layer tower plate structure, each tower plate is loaded with a catalyst bed, wherein n is an integer greater than 2, an inclined partition is arranged on the top of each catalyst bed, and a gas phase channel is arranged through each catalyst bed and the inclined partition; The gas phase channel is located in the middle of the two-stage catalytic distillation tower and passes through all catalyst beds from bottom to top; the lower end of the gas phase channel passing through the upper catalyst bed is connected to the inclined partition plate on the lower catalyst bed; The two-stage catalytic distillation tower also includes a liquid-phase feed subunit, which is arranged above the inclined partition of the topmost catalyst bed, through which the liquid-phase feed is guided to the catalyst bed; The two-stage catalytic distillation tower also includes a gas phase feed subunit, which is arranged between the catalyst bed layer of the upper layer and the inclined partition plate of the lower layer; The catalyst bed in the two-stage catalytic distillation tower is provided with: an overflow weir, which is arranged on the side close to the gas phase channel; and a liquid sealing baffle, which is arranged on the upper part of the overflow weir and is used to isolate the gas phase feed from the gas phase product.

2. The catalytic distillation apparatus according to claim 1, It is characterized in that The invention also comprises a gas circulation unit, which is used for selectively concentrating the gas obtained from the second-stage catalytic distillation tower and circulating the gas back to the first-stage catalytic distillation tower and the second-stage catalytic distillation tower.

3. The catalytic distillation apparatus according to claim 1, It is characterized in that In the one-stage catalytic distillation tower, based on the height of the one-stage catalytic distillation tower, the height ratios of the rectification section, the upper catalyst bed, the separation section and the lower catalyst bed are: 5%-20%: 40-60%: 10%-30%: 5%-20%.

4. The catalytic distillation apparatus according to claim 1, It is characterized in that The upper catalyst bed and the lower catalyst bed of the first-stage catalytic distillation tower are provided with a hydrotreating catalyst.

5. The catalytic distillation apparatus according to claim 1, It is characterized in that The rectifying section of a catalytic distillation tower is filled with packing or trays, or loaded with a hydrotreating catalyst.

6. The catalytic distillation apparatus according to claim 1, It is characterized in that An annular downcomer is arranged at the end of the inclined partition, and the bottom of the annular downcomer is spaced a distance from the bottom of the catalyst bed of the second-stage catalytic distillation tower, so that the liquid feed enters the catalyst bed in a radial direction.

7. The catalytic distillation apparatus according to claim 1, It is characterized in that The liquid seal baffle comprises: a horizontal portion which is annular and flat and located above the overflow weir; a vertical portion which is cylindrical and is integrally formed with the horizontal portion, and the lower end of the vertical portion is spaced a distance from the bottom of the catalyst bed.

8. The catalytic distillation apparatus according to claim 1, It is characterized in that The liquid phase feed subunit also includes: a liquid phase feed pipe, which extends in the radial direction of the catalyst bed; a liquid phase distribution pipe, which is annular and intersects orthogonally or tangentially with the liquid phase feed pipe, and the tube wall of the liquid phase distribution pipe is provided with multiple channels for evenly distributing the liquid phase feed to all directions of the annular downcomer.

9. The catalytic distillation apparatus according to claim 1, It is characterized in that The gas-phase feed subunit also includes: a gas-phase feed pipe, which extends in the radial direction of the catalyst bed; a gas-phase distribution pipe, which is annular or multi-layer concentric annular, and the gas-phase distribution pipe intersects the gas-phase feed pipe orthogonally or tangentially, and a plurality of channels are provided on the wall surface of the gas-phase distribution pipe for evenly distributing the gas-phase feed to all directions at the bottom of the catalyst bed.

10. The catalytic distillation apparatus according to claim 9, It is characterized in that The gas phase feeding subunit further comprises: a gas phase distribution plate, which is located at the bottom of the catalyst bed and is in the shape of a plate as a whole, and has a plurality of holes evenly and densely distributed on the gas phase distribution plate.

11. A catalytic distillation method for producing clean gasoline, using the catalytic distillation device according to claim 1, It is characterized in that The steps include: (1) After being heated, the gasoline feedstock enters the middle separation section of a first-stage catalytic distillation tower, wherein the light fraction is carried away by the hydrogen flowing upward from the bottom of the first-stage catalytic distillation tower and enters the upper catalyst bed and the rectifying section of the first-stage catalytic distillation tower upward, and undergoes diene hydrogenation, sulfide reaction and trans-olefin isomerization reaction under the action of the hydrotreating catalyst; the light gasoline after hydrotreating is extracted from the rectifying section; the heavy fraction and the sulfide compound generated by the reaction of the upper catalyst bed of the first-stage catalytic distillation tower enter the lower catalyst bed of the first-stage catalytic distillation tower downward, and react with the hydrogen entering from the lower part of the first-stage catalytic distillation tower, and the hydrogen sulfide generated by the reaction flows upward from the top of the tower under the carry-over of the hydrogen, and the heavy gasoline fraction flows downward; (2) The heavy gasoline fraction obtained in step (1) enters a second-stage catalytic distillation tower, descends in the tower and sequentially enters multiple catalyst beds, and contacts with hydrogen entering the catalyst beds of the second-stage catalytic distillation tower upward to undergo a hydrodesulfurization reaction; the gaseous product obtained by the reaction of each catalyst bed enters a gas phase channel, and flows upward out of the second-stage catalytic distillation tower in the gas phase channel; the liquid phase stream obtained by the reaction of each catalyst bed sequentially enters the next catalyst bed layer for reaction, and the liquid stream finally flows downward out of the second-stage catalytic distillation tower.

12. The catalytic distillation method according to claim 11, It is characterized in that After the gas phase at the top of the second-stage catalytic distillation tower is cooled, part of the condensate obtained is refluxed, and the remaining condensate and the liquid flow flowing out of the bottom of the second-stage catalytic distillation tower enter the stabilization tower together, and the heavy gasoline product is obtained from the bottom of the stabilization tower.

13. The catalytic distillation method according to claim 11, It is characterized in that The gasoline raw material is selected from one or a mixture of catalytic cracking gasoline, catalytic pyrolysis gasoline and thermal cracking gasoline.

14. The catalytic distillation method according to claim 11, It is characterized in that The operating conditions of the first stage catalytic distillation tower are as follows: reaction temperature is 100°C to 260°C, reaction pressure is 0.5MPa to 3.0MPa, hydrogen to oil volume ratio is 200 to 800, liquid hourly volume space velocity is 1.0h -1 ~10.0h -1 The extraction temperature of the distillation section is 60℃~120℃.

15. The catalytic distillation method according to claim 11, It is characterized in that The upper catalyst bed of the two-stage catalytic distillation tower is filled with a hydrodesulfurization catalyst, and the lower catalyst bed is filled with a hydroreforming catalyst; the layer ratio of the hydrodesulfurization catalyst to the hydroreforming catalyst is 1:1 to n-1:

1.

16. The catalytic distillation method according to claim 11, It is characterized in that The operating conditions of the two-stage catalytic distillation tower in step (2) are: reaction temperature of 220°C to 400°C, reaction pressure of 1.0MPa to 2.5MPa, hydrogen-to-oil volume ratio of 50 to 800, liquid hourly volume space velocity of 0.5h -1 ~8.0h -1 .

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