A gasoline catalytic distillation desulfurization device and method

Abstract

The present invention discloses a gasoline catalytic distillation desulfurization device and method. Gasoline is first pre-hydrogenated, and the pre-hydrogenation product is separated into a light fraction and a heavy fraction; the heavy fraction enters a catalytic distillation tower, and is subjected to a hydrodesulfurization reaction with the upward hydrogen in multiple catalyst beds in stages, and 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 component 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, and avoiding the problem of excessive mercaptan content in gasoline after desulfurization; at the same time, the reaction product quickly leaves the catalytic distillation tower after desulfurization, 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.

Description

Technical Field

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

[0002] In recent years, my country has increasingly stringent requirements on the quality of engine fuels to reduce the emission of harmful substances, among which the limits on the content of sulfur and olefins in automotive gasoline are more stringent. The Beijing 6B automotive gasoline standard implemented on December 1, 2021 requires that the volume fraction of olefins be no more than 12% and the mass fraction of sulfur be less than 10ppm. However, about 80% of domestic automotive gasoline is catalytic cracking gasoline, which has an olefin volume content of 30% to 45% and a high sulfur content. Therefore, how to achieve a higher desulfurization rate while moderately reducing the olefin content while minimizing the loss of octane number is an urgent problem to be solved.

[0003] With the increasing requirements for environmental protection, the use of lead antiknock agents is generally prohibited, and the sulfur content allowed in fuel oil is required to be continuously reduced. Therefore, the production process of clean fuel is particularly important. The sulfides in catalytic cracking gasoline (FCC gasoline for short) are mainly organic compounds, including mercaptans, sulfides, disulfides, tetrahydrothiophene, thiophene and benzothiophene, etc. Its stable conjugated structure makes it difficult to deeply desulfurize FCC gasoline. At the same time, the sulfur content of FCC gasoline increases with the weight of the fraction, while the olefin content decreases with the weight of the fraction. This shows that the sulfides in FCC gasoline are mainly concentrated in the heavier fractions, while the olefins are mainly concentrated in the lighter fractions. For this reason, several desulfurization methods have been developed at home and abroad. Among them, catalytic distillation technology is a new technology that couples the catalytic reaction process with the distillation separation process in the same reactor. Combining catalytic distillation technology with desulfurization technology can realize a series of advantages of catalytic distillation technology such as high conversion rate, good selectivity, low energy consumption, high product purity, easy operation and low investment in the desulfurization process.

[0004] Catalytic distillation technology has been applied to the selective hydrogenation and hydrodesulfurization of catalytic cracking gasoline, and has achieved good results. The more representative and industrialized one is the CDHydro / CDHDS selective hydrodesulfurization technology of CDTECH in the United States. It adopts a two-stage catalytic distillation method. The first stage uses the CDHydro tower to achieve the separation and refining of light / heavy gasoline components through reactive distillation. The top of the tower produces light gasoline with low content of diolefins and mercaptans. The second stage uses the CDHDS tower. The heavy gasoline and the generated sulfide compounds are removed during the distillation process, and the octane number loss is small. The problem with this method is that the desulfurization reaction and distillation separation of the catalytic distillation tower are carried out in stages, and the hydrogen sulfide produced by sulfur cannot be discharged from the reactor in time, which will cause hydrogen sulfide to combine with olefins to further generate mercaptans. The mercaptan content of gasoline after desulfurization is too high, or the re-decomposition of mercaptans on the lower catalyst module will also affect the desulfurization efficiency of the catalyst and the quality of the final product. In addition, the process flow is complicated and the heat load is large. Summary of the invention

[0005] In view of the shortcomings of the prior art, the object of the present invention is to provide a device and method for catalytic distillation desulfurization of gasoline, so as to overcome the problem that the desulfurization reaction and distillation separation in the catalytic distillation tower are carried out in stages in the prior art, so that the gas phase reaction products and hydrogen sulfide can be separated from the reaction zone in time. At the same time, while improving the desulfurization rate, the olefin content is appropriately reduced, while the octane number loss is small.

[0006] According to a first aspect of the present invention, a gasoline catalytic distillation desulfurization device is provided.

[0007] A gasoline catalytic distillation desulfurization device of the present invention comprises:

[0008] (1) A pre-hydrogenation reactor, which is used to carry out sulfide etherification, diene selective hydrogenation and isomerization reactions on the raw gasoline;

[0009] (2) a fractionation tower for separating the stream flowing out of the pre-hydrogenation reactor into a light gasoline fraction and a heavy gasoline fraction;

[0010] (3) A catalytic distillation tower, which receives the heavy gasoline component produced by the fractionation tower as a liquid feed, and the liquid feed flows from top to bottom through each catalyst bed in the distillation tower; the preheated hydrogen enters each catalyst bed from the bottom to the top uniformly; the liquid feed and hydrogen undergo a hydrodesulfurization reaction on a hydrorefining catalyst provided in the distillation tower; the hydrogen sulfide generated by the hydrodesulfurization and the unreacted gaseous feed are discharged from the top of the catalytic distillation tower through an independent gas phase channel, and the liquid product obtained by the hydrorefining is discharged from the bottom of the catalytic distillation tower.

[0011] Furthermore, the above technical solution also includes (4) a gas circulation unit, which is used to selectively concentrate the gas obtained in the second stage and circulate it back to the first catalytic distillation tower and the second catalytic distillation tower.

[0012] Furthermore, in the above technical solution, the catalytic distillation tower comprises at least one catalytic reaction zone, and the catalytic reaction zone is a 2-n-layer tower plate structure, and a hydrodesulfurization catalyst bed is arranged on each tower plate, wherein n is an integer greater than 2. An inclined partition is arranged above each catalyst bed, preferably an umbrella-shaped partition; and a gas phase channel is arranged through each catalyst bed and the inclined partition.

[0013] Furthermore, in the above technical solution, the catalytic distillation tower further comprises a liquid-phase feed subunit, which is arranged above the inclined partition of the uppermost catalyst bed, and the liquid-phase feed is guided to the uppermost catalyst bed through the inclined partition.

[0014] Furthermore, in the above technical solution, 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.

[0015] Furthermore, in the above technical solution, the 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.

[0016] Furthermore, in the above technical solution, the lower end of the gas phase channel passing through the upper catalyst bed is connected to the inclined partition plate on the next catalyst bed. This design makes the gas phase channel and the gas phase feed subunit relatively isolated, 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.

[0017] Furthermore, in the above technical solution, 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.

[0018] Furthermore, in the above technical solution, 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.

[0019] Furthermore, in the above technical solution, the liquid-phase feed subunit further includes: a liquid-phase feed pipe, which extends along 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.

[0020] Furthermore, in the above technical solution, the gas-phase feed subunit further includes: a gas-phase feed pipe, which extends along 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 holes 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.

[0021] Furthermore, in the above technical solution, 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 disk-shaped as a whole, and a plurality of holes are evenly and densely distributed on the gas phase distribution plate.

[0022] Furthermore, in the above technical solution, the gas phase channel is located in the middle of the catalytic reaction unit and passes through all catalyst beds from bottom to top.

[0023] Furthermore, in the above technical solution, the catalyst bed height is set to 10 mm to 1000 mm according to different reaction systems.

[0024] Furthermore, in the above technical solution, the upper edge of the overflow weir may be 10 to 100 mm higher than the upper surface of the catalyst bed.

[0025] Furthermore, in the above technical solution, the gas phase distribution pipe can be arranged below the catalyst bed or inside the catalyst bed.

[0026] The second aspect of the present invention is to provide a method for producing gasoline by catalytic distillation desulfurization. The method for producing gasoline by catalytic distillation desulfurization of the present invention comprises the following steps:

[0027] (1) After the gasoline feedstock is mixed with hydrogen, it enters the pre-hydrogenation reactor, where dienes are hydrogenated, mercaptans and dienes are sulfide-etherified, and some olefins are isomerized under the action of a hydrorefining catalyst;

[0028] (2) The stream flowing out of the pre-hydrogenation reactor in step (1) enters a fractionation tower for separation, and a light gasoline fraction is obtained at the top of the tower, and a heavy gasoline fraction is obtained at the bottom of the tower;

[0029] (3) The heavy gasoline fraction obtained in the kettle of step (2) enters a catalytic distillation tower, descends in the tower and enters a plurality of hydrodesulfurization catalyst beds in turn, contacts with hydrogen entering the catalyst beds upwardly to carry out a hydrodesulfurization reaction; the gaseous stream obtained by the reaction of each catalyst bed enters a gas phase channel, flows upwardly out of the catalytic distillation tower in the gas phase channel; the liquid product obtained by the reaction of each catalyst bed enters the next catalyst bed in turn to carry out a hydrodesulfurization reaction, and the liquid stream finally flows downward out of the catalytic distillation tower.

[0030] Furthermore, in the above technical scheme, after the gas phase at the top of the catalytic distillation tower is cooled, the non-condensable gas can be desulfurized to obtain hydrogen-rich gas, part of the condensate is refluxed, and the remaining part enters the stabilization tower together with the liquid phase flow out of the bottom of the tower. After the stabilization tower removes the non-condensable gas contained in it, the heavy gasoline product is obtained from the bottom of the stabilization tower.

[0031] Furthermore, in the above technical solution, the gasoline feedstock is selected from one or a mixture of catalytic cracking gasoline, catalytic pyrolysis gasoline, coking gasoline and thermal cracking gasoline. Furthermore, in the above technical solution, the obtained hydrogen-rich gas is recycled to step (1) or (3) for use.

[0032] Furthermore, in the above technical solution, the amount of light gasoline fraction obtained from the top of the fractionation tower is mainly limited by the sulfur content, and the extraction amount can be increased or decreased by adjusting the temperature and pressure of the fractionation tower. When the light gasoline extraction amount increases, the operating load of the catalytic distillation tower can be reduced, and the octane number loss of gasoline can be reduced, but at the same time, the sulfur content of the light gasoline will also increase.

[0033] Furthermore, in the above technical solution, the pre-hydrogenation reactor in step (1) is provided with a hydrorefining catalyst bed. The hydrorefining catalyst is generally based on alumina or silicon-containing alumina as a carrier, and has a VIB group and a group VIII metal as an active component, such as one, two or more selected from W, Mo, Co, and Ni.

[0034] Furthermore, in the above technical solution, the operating conditions of the pre-hydrogenation reactor described in step (1) 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 .

[0035] Furthermore, in the above technical solution, the operating conditions of the distillation tower described in step (2) are: tower top pressure 0.2MPa~2.0MPa, feed temperature 100℃~200℃, tower top temperature 60℃~120℃, tower bottom temperature 200℃~280℃.

[0036] Furthermore, in the above technical solution, the number of catalyst beds in the catalytic distillation tower in step (3) is n, and all catalyst beds can be loaded with hydrodesulfurization catalyst; preferably, the upper catalyst bed is loaded with hydrodesulfurization catalyst, and the lower catalyst bed is loaded with hydroreforming catalyst, and the layer ratio of hydrodesulfurization catalyst to hydroreforming catalyst is preferably 1:1~n-1:1. The hydrodesulfurization catalyst generally includes an active component and a carrier, and the carrier component includes 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, and Group VIB metals are generally Mo and / or W, and Group VIII metals are generally Co and / or Ni. The hydroreforming catalyst is generally based on ZSM-5, Beta, SAPO molecular sieve or a mixture thereof as a carrier, and metals of Group VIB and Group VIIIB as active components, such as one, two or more selected from W, Mo, Co, and Ni.

[0037] The hydrotreating catalyst, hydrodesulfurization catalyst and hydro-reforming catalyst may be in any conventional existing 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 recommended catalyst bed void ratio is 15% to 85%, preferably 20% to 75%.

[0038] Furthermore, in the above technical solution, the operating conditions of the catalytic distillation reactor 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 .

[0039] In the above technical solution, the gas phase product 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 and the gas phase feed subunit are in a relatively isolated state.

[0040] The heavy gasoline fraction obtained in step (2) of the above technical solution enters the first catalyst bed from the distributor arranged above the uppermost catalyst bed in the catalytic reaction distillation tower, and then enters each catalyst bed layer by layer from top to bottom through the liquid phase feed internal components arranged in the reactor.

[0041] Compared with the prior art, the advantages of the present invention are:

[0042] 1. The present invention adopts the design of layered tower components and gas phase channels to achieve a high degree of coupling between catalytic reaction and distillation separation. The hydrogen sulfide generated by the desulfurization reaction on each catalyst bed can immediately leave the reaction zone from the gas phase channel, overcoming the problem of separate desulfurization reaction and distillation separation in the catalytic distillation tower in the prior art, and can effectively prevent hydrogen sulfide from further combining with olefins to form mercaptans, thereby avoiding the problem of excessive mercaptan content in gasoline after desulfurization.

[0043] 2. The catalytic distillation tower can make the heavy gasoline fractions 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 after desulfurization quickly leave the catalytic distillation tower, which is conducive to promoting the reaction to the right, increasing the reaction rate and liquid yield, and reducing the heat load of the device.

[0044] 3. The inclined partition can separate the gas phase feed and product gas between adjacent beds on the one hand, and play a role in guiding the liquid phase and gas phase on the other hand. The liquid seal baffle can effectively isolate the gas phase feed and gas phase product. The setting of multiple concentric annular gas phase distribution pipes can keep the distribution of gas phase feed uniform to the maximum extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a schematic diagram of the principle flow chart of the present invention.

[0046] Figure 2 It is a structural schematic diagram of the catalytic reaction distillation tower of the present invention.

[0047] Figure 3 It is a top view of the liquid phase distribution pipe in the catalytic reaction distillation tower of the present invention.

[0048] 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).

[0049] 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).

[0050] 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.

[0051] Figure 7 It is a top view of the gas phase distribution plate in the catalytic reaction distillation tower of the present invention.

[0052] Figure 8It is a top view of the catalyst support plate in the catalytic reaction distillation tower of the present invention.

[0053] Fig. 9 It is a schematic diagram of the top structure of a liquid distribution assembly according to one embodiment of the present invention.

[0054] 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.

[0055] 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.

[0056] Fig.12 yes Fig.10 Schematic diagram of the three-dimensional structure of the first overflow ring.

[0057] Description of main reference numerals:

[0058] 1- catalytic distillation tower, 2- pre-hydrogenation reactor, 3- fractionation tower, 4, 6- condenser, 5, 7- reflux tank, 8- stabilization tower, L1- gasoline, G1- hydrogen, L2- heavy gasoline fraction, G2- light gasoline fraction, G3- non-condensable gas at the top of the fractionation tower, L3- light gasoline product, G4- catalytic distillation gas phase logistics, L4- catalytic distillation liquid logistics, G5- non-condensable gas at the top of the catalytic distillation tower, L6- heavy gasoline product, G6- non-condensable gas at the top of the stabilization tower.

[0059] 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;

[0060] 21-liquid phase feed pipe, 22-liquid phase distribution pipe, 220-liquid phase distribution pipe body, 221-liquid phase channel;

[0061] 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;

[0062] Sawtooth portion 14-1, guide groove 14-2. DETAILED DESCRIPTION

[0063] 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.

[0064] Figure 1 The figure shows a process flow diagram of gasoline catalytic distillation desulfurization according to the present invention. Figure 1As shown, gasoline L1 is mixed with hydrogen G1 and enters the pre-hydrogenation reactor 2, where diene hydrogenation, sulfide reaction and isomerization reaction are carried out under the action of the hydrorefining catalyst. The logistics flowing out of the pre-hydrogenation reactor 2 enters the fractionation tower 3 for separation, and the light gasoline fraction G2 is obtained at the top of the tower, and the heavy gasoline fraction L2 is obtained at the bottom of the tower. The light gasoline fraction G2 flows out from the top of the tower and enters the condenser 4. After condensation, the material enters the reflux tank 5. The non-condensable gas G3 at the top of the fractionation tower can be recycled as hydrogen-rich gas after desulfurization of hydrogen. The condensed liquid part flows back to the fractionation tower 3, and the remaining part is discharged from the device as the light gasoline product L3.

[0065] The heavy gasoline fraction L2 enters the liquid phase feed pipe 21 of the 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 catalytic distillation liquid stream L4 flows downward out of the catalytic distillation tower 1 and enters the stabilization tower 8. The catalytic distillation gas phase stream 8 from the gas phase channel 13 flows out from the top of the 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 catalytic distillation tower can be recycled as hydrogen-rich gas after desulfurization of hydrogen. The condensed liquid part flows back to the catalytic distillation tower 1, and the remaining condensed liquid L5 at the top of the 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.

[0066] 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.

[0067] Further, if Figure 2 As 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] Example 1

[0072] 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.

[0073] After gasoline and hydrogen are mixed, they enter the pre-hydrogenation reactor, where diene hydrogenation, thioetherification of mercaptans and dienes, and isomerization of some olefins are carried out under the action of the hydrorefining catalyst FH-40C (trademark, produced by Sinopec Dalian Petrochemical Research Institute). The stream flowing out of the pre-hydrogenation reactor enters the fractionation tower for separation, and the light gasoline fraction is obtained at the top of the tower, and the heavy gasoline fraction is obtained at the bottom of the tower. The operating pressure of the fractionation tower is 0.8MPa, the top temperature is 75℃, and the bottom temperature is 215℃.

[0074] The catalytic reaction distillation tower is provided with 5 layers of trays. The 1st to 4th layers of trays are loaded with hydrodesulfurization catalyst ME-1, and the 5th layer is loaded with hydro-reforming catalyst FDW-3. All catalysts used are produced by Sinopec Dalian Petrochemical Research Institute. The single-layer catalyst bed height is 500mm, and the overflow weir height is 80mm. The obtained heavy gasoline fraction enters the 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.

[0075] 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.

[0076] The reaction process conditions are shown in Table 2, and the properties of the clean gasoline product are shown in Table 3.

[0077] Example 2

[0078] The difference between this embodiment and embodiment 1 is that the catalytic reaction distillation tower is provided with 8 catalyst beds, the 1st to 7th trays are loaded with hydrodesulfurization catalyst ME-1, the 8th tray is loaded 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 remaining conditions are the same as those in embodiment 1.

[0079] Example 3

[0080] The difference between this embodiment and embodiment 1 is that the catalytic reaction distillation tower is provided with 10 catalyst beds, the 1st to 8th trays are loaded with hydrodesulfurization catalyst ME-1, the 9th and 10th trays are loaded 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.

[0081] Embodiment 4-5

[0082] 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.

[0083] Comparative Example 1

[0084] The catalytic distillation tower adopts the CDHDS tower in the industrialized CDHydro / CDHDS selective hydrodesulfurization technology. The CDHDS tower has 5 catalyst modules. 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.

[0085] Table 1 Main properties of catalytic cracking gasoline

[0086]

[0087] Table 2 Example process conditions

[0088]

[0089] Table 3 Clean gasoline product properties

[0090]

[0091] 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 14%, a sulfur mass fraction of less than 10 ppm, an antiknock index loss of less than 1.0, and a low mercaptan content. However, the total sulfur content of Comparative Example 1 exceeded 26 ppm, the mercaptan content exceeded the standard, and the antiknock index loss was 1.5.

Claims

1. A gasoline catalytic distillation desulfurization device, It is characterized in that include: (1) A pre-hydrogenation reactor, which is used to carry out sulfide etherification, diene selective hydrogenation and isomerization reactions on the raw gasoline; (2) a fractionation tower for separating the liquid stream obtained from the pre-hydrogenation reactor into a light gasoline fraction and a heavy gasoline fraction; (3) a catalytic distillation tower, which receives the heavy gasoline component produced by the fractionation tower as a liquid feed, and the liquid feed flows from top to bottom through each catalyst bed in the distillation tower; The preheated hydrogen enters each catalyst bed evenly from the bottom of each catalyst bed from bottom to top; The liquid feed and hydrogen undergo a hydrodesulfurization reaction on a hydrodesulfurization catalyst arranged in the distillation tower; the hydrogen sulfide generated by the hydrodesulfurization and the unreacted gaseous feed are discharged from the top of the catalytic distillation tower through an independent gas phase channel, and the liquid product obtained by the hydrodesulfurization is discharged from the bottom of the catalytic distillation tower; The 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 provided with a hydrodesulfurization catalyst bed, wherein n is an integer greater than 2; an inclined partition is provided above each catalyst bed, and a gas phase channel is provided through each catalyst bed and the inclined partition; The gas phase channel is located in the middle of the catalytic reaction unit 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 next catalyst bed; The catalytic distillation column further comprises a liquid-phase feed subunit, which is disposed above the inclined partition of the uppermost catalyst bed, through which the liquid-phase feed is guided to the uppermost catalyst bed; The 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 is also 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 device according to claim 1, It is characterized in that An annular downcomer is disposed 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.

3. The device 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 a lower end of the vertical portion is spaced a distance from the bottom of the catalyst bed.

4. The device according to claim 1, It is characterized in that The liquid phase feed subunit 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 pipe 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.

5. The device according to claim 1, It is characterized in that The gas-phase feed subunit comprises: a gas-phase feed pipe, which extends in the radial direction of the catalyst bed; a gas-phase distribution pipe, which is in an annular shape or a multi-layer concentric annular shape, and the gas-phase distribution pipe intersects the gas-phase feed pipe orthogonally or tangentially, and a plurality of holes are arranged 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.

6. The device according to claim 5, 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 a plurality of holes are evenly and densely distributed on the gas phase distribution plate.

7. A method for producing gasoline by catalytic distillation desulfurization, which uses the gasoline catalytic distillation desulfurization device according to any one of claims 1 to 6, It is characterized in that The steps include: (1) After the gasoline feedstock is mixed with hydrogen, it enters the pre-hydrogenation reactor, where dienes are hydrogenated, mercaptans and dienes are sulfide-etherified, and some olefins are isomerized under the action of a hydrorefining catalyst; (2) The liquid stream obtained from the pre-hydrogenation reactor in step (1) enters a distillation tower for separation, and a light gasoline fraction is obtained at the top of the tower, and a heavy gasoline fraction is obtained at the bottom of the tower; (3) The heavy gasoline fraction obtained in the kettle of step (2) enters a catalytic distillation tower, descends in the tower and enters a plurality of hydrodesulfurization catalyst beds in turn, contacts with hydrogen entering the catalyst beds upwardly to carry out a hydrodesulfurization reaction; the gaseous stream obtained by the reaction of each catalyst bed enters a gas phase channel, flows upwardly out of the catalytic distillation tower in the gas phase channel; the liquid product obtained by the reaction of each catalyst bed enters the next catalyst bed in turn to carry out a hydrodesulfurization reaction, and the liquid stream finally flows downward out of the catalytic distillation tower.

8. The method according to claim 7, It is characterized in that After the gas phase at the top of the catalytic distillation tower is cooled, part of the condensate is refluxed, and the remaining part of the condensate enters the stabilization tower together with the liquid phase flow out of the bottom of the tower, and the heavy gasoline product is obtained at the bottom of the stabilization tower.

9. The method according to claim 7, It is characterized in that The gasoline raw material is selected from one or a mixture of catalytic cracking gasoline, catalytic pyrolysis gasoline, coking gasoline and thermal cracking gasoline.

10. The method according to claim 7, It is characterized in that The operating conditions of the pre-hydrogenation reactor 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 .

11. The method according to claim 7, It is characterized in that The operating conditions of the distillation tower in step (2) are: tower top pressure 0.2 MPa ~ 2.0 MPa, feed temperature 100 ° C ~ 200 ° C, tower top temperature 60 ° C ~ 120 ° C, tower bottom temperature 200 ° C ~ 280 ° C.

12. The method according to claim 7, It is characterized in that A hydro-reforming catalyst bed is arranged below the hydro-desulfurization catalyst bed, and the layer ratio of the hydro-desulfurization catalyst to the hydro-reforming catalyst is 1:1 to n-1:

1.

13. The method according to claim 7, It is characterized in that The operating conditions of the 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 .

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