Vacuum tower for slurry bed residual oil hydrogenation device

Abstract

The utility model relates to the technical field of petrochemical engineering, in particular to a vacuum tower for a slurry bed residual oil hydrogenation device, which comprises a tower body, a vacuum fourth distributor, a gas stripping distributor and a heavy wax oil line, a plurality of liquid collecting tower plates are arranged in the tower body from top to bottom at intervals, the vacuum fourth distributor comprises a vacuum fourth downward return pipeline and a vacuum fourth downward return distribution pipe, and the gas stripping distributor is arranged in the tower body. The gas stripping distributor comprises a steam inlet pipeline, an annular distribution pipe and two straight rod distribution pipes, the annular distribution pipe is arranged on the inner side wall of the tower body, and the two straight rod distribution pipes are arranged in the middle of the tower body. According to the device disclosed by the utility model, the two vacuum four-down-return distribution pipes are arranged, so that the vacuum four-down-return quantity is increased, the spraying effect is improved, the feeding temperature is reduced through a heavy wax oil line, slurry is diluted at the first time, the thermal stability of asphaltene is improved, and the probability of blockage of a gas stripping filter is reduced; and the tower bottom material retention time is shortened.

Description

Technical Field

[0001] This utility model relates to the field of petrochemical technology, and in particular to a vacuum tower for a slurry bed residue oil hydrogenation unit. Background Technology

[0002] Crude oil is a key aspect of my country's energy security. How to efficiently utilize crude oil resources and reduce external demand has become a common challenge for domestic professionals and companies. In order to maximize the utilization of crude oil, the deep conversion and utilization of heavy fractions, especially heavy oil fractions, is crucial.

[0003] Heavy oil is a byproduct of atmospheric and vacuum distillation units in refineries. Currently, the main methods for processing heavy oil are catalytic cracking and hydrocracking. The current domestic processing trend leans towards slurry-bed hydrocracking to achieve lighter oil. However, its ash, asphaltenes, and gum content are also high, resulting in high viscosity, poor fluidity, high surface tension, easy coking and deposition, and easy blockage when it enters fractionation after the reaction, especially in the lower part of the vacuum distillation tower. During the coking process, the H / C ratio of the coke is between 0.5 and 1.5. It is a carbonaceous organic compound that is insoluble in a certain solvent. The thermal reaction of heavy oil is a parallel sequential reaction. The reason for coke formation is the result of complex physicochemical reactions of large molecular hydrocarbons through condensation and polymerization reactions.

[0004] Analytical methods separate heavy oil into four components: saturated fraction, aromatic fraction, gums, and asphaltenes. The saturated fraction is mainly composed of various branched chains and relatively long aliphatic chains, with virtually no aromatic rings or heteroatoms. During hydrocracking, it produces gases and light fractions such as gasoline, without undergoing cyclization or aromatization reactions. The saturated fraction promotes coking reactions because its strong hydrogen-repellent ability reduces the hydrogen supply from aromatic fractions and gums to asphaltenes, promoting the condensation reaction of large asphaltenes. In hydrocracking, aromatic fractions mainly undergo thermal cracking free radical reactions, condensing to form gums while producing light distillate oils. This process continues with increasing reaction time and... As the reaction temperature increases, the generated gums will further condense to form asphaltenes. However, the asphaltenes will not convert into carbon deposits under sufficient hydrogen supply. At high temperatures, aromatics will crack to form saturated fractions. Saturated fractions have a strong ability to attract hydrogen, which will increase the coking rate. In order to reduce the risk of coking, the temperature should not be too high to prevent excessive conversion of aromatics into saturated fractions. During the hydrocracking process, gums generate light distillate oils. Under low space velocity conditions, the yield of light distillate oils increases. The structures of both gums and asphaltenes are relatively complex. It is generally believed that gums encapsulate asphaltenes. During the heating process, gums are the main hydrogen donor for asphaltenes.

[0005] Heavy oil entering a slurry-bed residue hydrocracking unit typically achieves a conversion rate of around 92%. Further separation via slurry fractionation and atmospheric fractionation yields products such as liquefied petroleum gas (LPG), light naphtha, heavy naphtha, diesel oil, light wax, wax oil, and heavy wax. The bottom residue from the vacuum distillation tower is sent to downstream gasification units for hydrogen production and precious metal recovery. Simultaneously, due to the high reaction conversion rate and effective separation by the slurry fractionation system, most of the ash, catalyst, asphaltenes, and gums accumulate at the bottom of the vacuum distillation tower.

[0006] Heavy vacuum slurry contains a large amount of asphaltenes, gums, and solid particles, posing a challenge to the design of vacuum towers. The presence of these substances exacerbates deposition and coking, leading to blockage. Conventional vacuum tower designs cannot effectively solve the problems of coking and blockage caused by these substances. This necessitates special design and operational optimization of the vacuum tower's packing, distributors, and stripping distributors to reduce the rate of coking and blockage at the bottom of the vacuum tower and ensure long-term stable operation of the equipment. Utility Model Content

[0007] The purpose of this invention is to solve the problems in the prior art and provide a vacuum tower for a slurry bed residue oil hydrogenation unit.

[0008] The technical solution of this utility model is:

[0009] A vacuum tower for a slurry bed residue hydrotreating unit includes a tower body with a vacuum system at the top and a conical outlet at the bottom. Several liquid collection trays are spaced apart from top to bottom within the tower body, dividing the interior into vacuum zones 1, 2, 3, and 4, and a bottom separation zone. The tower also includes a vacuum zone 4 distributor, a stripping distributor, and a heavy wax oil line. The vacuum zone 4 distributor includes a vacuum zone 4 lower return pipe and two vacuum zone 4 lower return distribution pipes, which are parallel to each other and connected to the vacuum zone 4 lower return pipe via a flange. The stripping distributor includes a steam inlet pipe, an annular distribution pipe, and two straight rod distribution pipes. The annular distribution pipe is located on the inner wall of the tower body, and the two straight rod distribution pipes are located in the middle of the tower body. Both the annular distribution pipe and the two straight rod distribution pipes are connected to the steam inlet pipe.

[0010] Preferably, the heavy wax oil line includes a wax oil feed pipe, a first wax oil distribution pipe, and a second wax oil distribution pipe. The first wax oil distribution pipe is located in the reduced pressure zone 4 and is connected to the wax oil feed pipe through a first branch. The second wax oil distribution pipe is located in the bottom separation zone of the tower and is located below the reduced pressure zone 4 return distribution pipe. The second wax oil distribution pipe is connected to the wax oil feed pipe through a second branch.

[0011] Preferably, a herringbone tray is provided inside the tower body, and the herringbone tray is positioned between the straight rod distribution pipe and the second wax oil distribution pipe.

[0012] Preferably, it also includes a feed distributor, which includes a slurry feed pipeline and a feed distribution pipe that are interconnected. The feed distribution pipe is located inside the tower body and above the reduced pressure return distribution pipe.

[0013] The pre-selected reducer distributor also includes a reducer pump, a reducer drain pipe, a reducer up return pipe, and a reducer discharge pipe. The reducer drain pipe is connected to the inlet of the reducer pump, and the reducer up return pipe, reducer down return pipe, and reducer discharge pipe are all connected to the outlet of the reducer pump. The reducer up return pipe is connected to the flange of the first wax oil distribution pipe, and a first heat exchanger is installed on the reducer up return pipe.

[0014] Preferably, the tower body is provided with a first packing layer, a second packing layer, a third packing layer, a fourth packing layer and a fifth packing layer from top to bottom. The first packing layer is located in the first reduction zone, the second packing layer is located in the second reduction zone, the third packing layer is located in the third reduction zone, and the fourth and fifth packing layers are located in the fourth reduction zone.

[0015] Preferably, the fifth packing layer consists of corrugated packing and grid packing.

[0016] Preferably, the system also includes a first-stage distributor, a second-stage distributor, and a third-stage distributor. The first-stage distributor includes a first-stage oil pump, a first-stage oil pumping pipe, a first-stage upward return pipe, a first-stage upward return distribution pipe, a first-stage downward return pipe, a first-stage downward return distribution pipe, and a first-stage discharge pipe. The inlet of the first-stage oil pump is connected to the tower body via the first-stage oil pumping pipe. The first-stage upward return pipe, the first-stage downward return pipe, and the first-stage discharge pipe are all connected to the outlet of the first-stage oil pump. The first-stage upward return distribution pipe is located above the first packing layer and is connected to the flange of the first-stage upward return pipe. A second heat exchanger is installed on the first-stage upward return pipe. The first-stage downward return distribution pipe is located above the second packing layer and is connected to the flange of the first-stage downward return pipe. The second-stage distributor includes a second-stage oil pumping pipe. The system includes a pump, a reduced-pressure pumping pipe, a reduced-pressure pumping return pipe, a reduced-pressure pumping return distribution pipe, and a reduced-pressure pumping discharge pipe. The inlet of the reduced-pressure pumping pump is connected to the tower body through the reduced-pressure pumping pipe. The reduced-pressure pumping return pipe and the reduced-pressure pumping discharge pipe are both connected to the outlet of the reduced-pressure pumping pump. The reduced-pressure pumping return distribution pipe is located above the third packing layer and is connected to the flange of the reduced-pressure pumping return pipe. The reduced-pressure pumping distributor includes a reduced-pressure pumping pump, a reduced-pressure pumping pipe, a reduced-pressure pumping return pipe, a reduced-pressure pumping return distribution pipe, and a reduced-pressure pumping discharge pipe. The inlet of the reduced-pressure pumping pump is connected to the tower body through the reduced-pressure pumping pipe. The reduced-pressure pumping return pipe and the reduced-pressure pumping discharge pipe are both connected to the outlet of the reduced-pressure pumping pump. The reduced-pressure pumping return distribution pipe is located above the fourth packing layer and is connected to the flange of the reduced-pressure pumping return pipe.

[0017] Compared with the prior art, the beneficial effects of this utility model are:

[0018] This invention improves the spraying effect by setting two reduced-pressure return distribution pipes to increase the amount of reduced-pressure return. By adding a heavy wax oil line on the tower body, the feed temperature of the vacuum tower is guaranteed not to exceed 340℃, which reduces the feed temperature and can also dilute the feed slurry in time, improving the thermal stability of the asphalt and reducing the probability of blockage of the air stripping filter. By installing the annular distribution pipe and the straight rod distribution pipe of the air stripping distributor on the side wall and inside the tower body respectively, the residence time of the material at the bottom of the tower is shortened, making it less likely to deposit on the tower wall and reducing the condensation of polycyclic hydrocarbons. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of this utility model.

[0020] The components include: 1. Tower body; 2. Vacuum system; 3. Conical outlet; 4. Liquid collection tray; 5. Reduced pressure zone 1; 6. Reduced pressure zone 2; 7. Reduced pressure zone 3; 8. Reduced pressure zone 4; 9. Bottom separation zone; 10. Reduced pressure zone 4 lower return pipeline; 11. Reduced pressure zone 4 lower return distribution pipeline; 12. Steam inlet pipeline; 13. Circular distribution pipeline; 14. Straight rod distribution pipeline; 15. Wax oil feed pipeline; 16. First wax oil distribution pipeline; 17. Second wax oil distribution pipeline; 18. First branch; 19. Second branch; 20. Herringbone tray; 21. Slurry feed pipeline; 22. Feed distribution pipeline; 23. Reduced pressure zone 4 oil pump; 24. Reduced pressure zone 4 oil discharge pipeline; 25. Reduced pressure zone 4 upper return pipeline; 26. Reduced pressure zone 4 discharge pipeline; 27. 1. First packing layer; 28. Second packing layer; 29. ​​Third packing layer; 30. Fourth packing layer; 31. Fifth packing layer; 32. Reduced-off oil pump 1; 33. Reduced-off oil pipe 1; 34. Reduced-off upward return pipe 1; 35. Reduced-off upward return distribution pipe 1; 36. Reduced-off downward return pipe 1; 37. Reduced-off downward return distribution pipe 1; 38. Reduced-off discharge pipe 1; 39. Reduced-off oil pump 2; 40. Reduced-off oil pipe 2; 41. Reduced-off downward return pipe 2; 42. Reduced-off downward return distribution pipe 2; 43. Reduced-off discharge pipe 2; 44. Reduced-off oil pump 3; 45. Reduced-off oil pipe 3; 46. Reduced-off downward return pipe 3; 47. Reduced-off downward return distribution pipe 3; 48. Reduced-off discharge pipe 3; 49. First heat exchanger; 50. Second heat exchanger. Detailed Implementation

[0021] To make the technical means, technical features, utility model purpose and technical effects of this utility model easier to understand, the present utility model will be further described below with reference to specific illustrations.

[0022] like Figure 1As shown, a vacuum tower for a slurry bed residue hydrotreating unit includes a tower body 1. A vacuum system 2 is connected to the top of the tower body 1 to extract gas from the tower body 1 and reduce the pressure inside the tower body 1. The bottom of the tower body 1 is a conical outlet 3 for discharging the vacuum residue. Several liquid collecting trays 4 are installed at intervals from top to bottom inside the tower body 1, dividing the interior of the tower body 1 into a vacuum reduction zone 1 5, a vacuum reduction zone 2 6, a vacuum reduction zone 3 7, a vacuum reduction zone 4 8, and a bottom separation zone 9. A vacuum reduction distributor is connected to the vacuum reduction zone 1 5, a vacuum reduction distributor is connected to the vacuum reduction zone 2 6, a vacuum reduction distributor is connected to the vacuum reduction zone 3 7, a vacuum reduction distributor is connected to the vacuum reduction zone 4 8, and a vacuum reduction distributor is connected to the bottom separation zone 9. The tower has a heavy wax oil line and a feed distributor. Inside the tower body 1, from top to bottom, there are a first packing layer 27, a second packing layer 28, a third packing layer 29, a fourth packing layer 30, and a fifth packing layer 31. The first packing layer 27 is located in the first reduction zone 5, the second packing layer 28 is located in the second reduction zone 6, the third packing layer 29 is located in the third reduction zone 7, and the fourth and fifth packing layers 30 and 31 are both located in the fourth reduction zone 8. The fifth packing layer 31 is designed with M125Y structured corrugated packing and M40AF grid structured packing to improve the separation effect of wax oil components, thereby increasing the yield of wax oil. Compared with corrugated packing, the increased gap fundamentally avoids the risk of blockage and reduces the coking rate.

[0023] like Figure 1 As shown, the feed distributor includes a slurry feed pipe 21 and a feed distribution pipe 22. The feed distribution pipe 22 is located inside the tower body 1 and is connected to the slurry feed pipe 21 to realize the delivery and spraying of slurry into the tower body 1.

[0024] like Figure 1 As shown, the heavy wax oil line includes a wax oil feed pipe 15, a first branch 18, a second branch 19, a first wax oil distribution pipe 16, and a second wax oil distribution pipe 17. The first wax oil distribution pipe 16 is installed in the reduced pressure zone 8 and is connected to the wax oil feed pipe 15 through the first branch 18. The second wax oil distribution pipe 17 is installed in the bottom separation zone 9 and is connected to the wax oil feed pipe 15 through the second branch 19. By adding a heavy wax oil line, the feed temperature is reduced when the slurry enters the tower body 1. It can also dilute the slurry as soon as it enters the tower body 1, improve the thermal stability of the asphalt, and reduce the probability of the bottom filter of the tower body 1 becoming clogged.

[0025] like Figure 1As shown, the vacuum distillation distributor includes a vacuum distillation pump 23, a vacuum distillation discharge pipe 24, a vacuum distillation upper return pipe 25, a vacuum distillation discharge pipe 26, a vacuum distillation lower return pipe 10, and a vacuum distillation lower return distribution pipe 11. The vacuum distillation discharge pipe 24 is connected to the tower body 1. The inlet of the vacuum distillation pump 23 is connected to the vacuum distillation discharge pipe 24 for extracting the separated liquid components. The vacuum distillation upper return pipe 25, the vacuum distillation discharge pipe 26, and the vacuum distillation lower return pipe 10 are all connected to the outlet of the vacuum distillation pump 23. The reflux of the liquid components is achieved through the vacuum distillation upper return pipe 25 and the vacuum distillation lower return pipe 10, and the designated discharge of the liquid components is achieved through the vacuum distillation discharge pipe 26. The vacuum distillation upper return pipe 25 is connected to the first wax oil distribution pipe 16. A first heat exchanger 49 is installed on the upper return pipeline 25 of the reduced pressure section via a flange connection, where heat exchange occurs during the upper return flow. There are two lower return distribution pipes 11, which are installed in parallel above the bottom separation zone 9 of the tower and below the feed distribution pipe 22. The two lower return distribution pipes 11 are interconnected and connected to the lower return pipeline 10 via flanges. By setting two lower return distribution pipes 11, double spraying is achieved, enhancing the distribution effect and increasing the return flow of the lower return pipeline. The flange connection allows for detachable connection, and disassembled parts can freely enter and exit the tower body 1 through the manhole for convenient maintenance and repair.

[0026] like Figure 1 As shown, the air-lift distributor includes a steam inlet pipe 12, an annular distribution pipe 13, and two straight rod distribution pipes 14. The annular distribution pipe 13 and the two straight rod distribution pipes 14 are all connected to the steam inlet pipe 12. The annular distribution pipe 13 is installed on the inner wall of the tower body 1, and the two straight rod distribution pipes 14 are located in the middle of the tower body 1. The distribution is reasonable, the steam spray range is wide, and the steam and slurry are in full contact, which improves the air-lift effect and efficiency.

[0027] like Figure 1 As shown, a herringbone tray 20 is also installed inside the tower body 1. The herringbone tray 20 is located between the straight rod distribution pipe 14 and the second wax oil distribution pipe 17. The herringbone tray 20 enables the gas to flow continuously up and down and left and right inside the tower body 1, increasing the chance of gas-liquid contact and thus achieving better separation.

[0028] like Figure 1As shown, the reducer distributor includes a reducer pump 32, a reducer pipe 33, a reducer upper return pipe 34, a reducer upper return distribution pipe 35, a reducer lower return pipe 36, a reducer lower return distribution pipe 37, and a reducer discharge pipe 38. The inlet of the reducer pump 32 is connected to the tower body 1 through the reducer pipe 33. The reducer upper return pipe 34, the reducer lower return pipe 36, and the reducer discharge pipe 38 are all connected to the outlet of the reducer pump 32. The reducer upper return distribution pipe 35 is located inside the tower body 1 and is installed above the first packing layer 27. The simplified upper return distribution pipe is connected to the reducer upper return pipe 34 through a flange for easy disassembly and assembly. A second heat exchanger 50 is installed on the reducer upper return pipe 34 for heat exchange. The reducer lower return distribution pipe 37 is located above the second packing layer 28 and is connected to the reducer lower return pipe 36 through a flange.

[0029] The reduced pressure distributor includes a reduced pressure pump 39, a reduced pressure pump pipe 40, a reduced pressure return pipe 41, a reduced pressure return distribution pipe 42, and a reduced pressure discharge pipe 43. The inlet of the reduced pressure pump 39 is connected to the tower body 1 through the reduced pressure pump pipe 40. The reduced pressure return pipe 41 and the reduced pressure discharge pipe 43 are both connected to the outlet of the reduced pressure pump 39. The reduced pressure return distribution pipe 42 is located above the third packing layer 29. The reduced pressure return distribution pipe 42 is connected to the reduced pressure return pipe 41 through a flange.

[0030] The three-stage distributor includes a three-stage oil pump 44, a three-stage oil pumping pipe 45, a three-stage return pipe 46, a three-stage return distribution pipe 47, and a three-stage discharge pipe 48. The inlet of the two-stage oil pump 39 is connected to the tower body 1 through the three-stage oil pumping pipe 45. The three-stage return pipe 46 and the three-stage discharge pipe 48 are both connected to the outlet of the three-stage oil pump 44. The three-stage return distribution pipe 47 is located above the fourth packing layer 30 and is flanged to the three-stage return pipe 46.

[0031] Multiple stages of separation and distillation are achieved by using a reducing distributor, a reducing distributor, and a reducing distributor installed on column body 1, in conjunction with a reducing distributor.

[0032] By setting two reduced pressure return distribution pipes 11, the amount of reduced pressure return is increased, improving the spraying effect. By adding a heavy wax oil line on the tower body 1, the feed temperature of the vacuum tower is ensured not to exceed 340℃. Lowering the feed temperature also allows for the dilution of the feed slurry in the first instance, improving the thermal stability of the asphalt and reducing the probability of blockage of the air stripping filter. By installing the annular distribution pipe 13 and the straight rod distribution pipe 14 of the air stripping distributor on the side wall and inside the tower body 1, respectively, the residence time of the material at the bottom of the tower is shortened, making it less likely for sediment to deposit on the tower wall and reducing the condensation of polycyclic hydrocarbons.

[0033] The above description is merely a preferred embodiment of this utility model and is not intended to limit the scope of this utility model. All equivalent changes and modifications made in accordance with the scope of the claims of this utility model should fall within the technical scope of this utility model.

Claims

1. A vacuum column for a slurry bed resid hydroprocessing unit, characterized by: The application relates to a tower body (1) provided with a vacuum extraction system (2) at the top, a conical outlet (3) at the bottom, a plurality of liquid collecting tower plates (4) arranged in the tower body (1) from top to bottom, a first reduction zone (5), a second reduction zone (6), a third reduction zone (7), a fourth reduction zone (8) and a tower bottom separation zone (9) formed by the liquid collecting tower plates (4), a fourth reduction distributor, a gas stripping distributor and a heavy wax oil line, the fourth reduction distributor comprises a fourth reduction return pipeline (10) and a fourth reduction return distribution pipe (11), the fourth reduction return distribution pipe (11) is provided with two, the two fourth reduction return distribution pipes (11) are arranged in parallel on the upper portion of the tower bottom separation zone (9), the two fourth reduction return distribution pipes (11) are connected with each other and are connected with the fourth reduction return pipeline (10) through flanges, the gas stripping distributor comprises a steam inlet pipeline (12), an annular distribution pipe (13) and two straight rod distribution pipes (14), the annular distribution pipe (13) is arranged on the inner wall of the tower body (1), the two straight rod distribution pipes (14) are arranged in the middle of the tower body (1), and the annular distribution pipe (13) and the two straight rod distribution pipes (14) are connected with the steam inlet pipeline (12).

2. The vacuum column for slurry-bed resid hydroprocessing units of claim 1, characterized by: The heavy wax oil line comprises a wax oil feeding pipeline (15), a first wax oil distribution pipe (16) and a second wax oil distribution pipe (17), the first wax oil distribution pipe (16) is arranged in the fourth reduction zone (8), the first wax oil distribution pipe (16) is connected with the wax oil feeding pipeline (15) through a first branch pipeline (18), the second wax oil distribution pipe (17) is arranged in the tower bottom separation zone (9) and is located below the fourth reduction return distribution pipe (11), and the second wax oil distribution pipe (17) is connected with the wax oil feeding pipeline (15) through a second branch pipeline (19).

3. The vacuum column for slurry-bed resid hydroprocessing units of claim 2, characterized by: A person pyramid (20) is arranged in the tower body (1) and between the straight rod distribution pipe (14) and the second wax oil distribution pipe (17).

4. The vacuum column for slurry-bed resid hydroprocessing units of claim 1, wherein: The application further comprises a feed distributor, the feed distributor comprises a slurry feeding pipeline (21) and a feed distribution pipe (22) connected with each other, the feed distribution pipe (22) is arranged in the tower body (1) and is located above the fourth reduction return distribution pipe (11).

5. The vacuum column for slurry-bed resid hydroprocessing units of claim 1, wherein: The fourth reduction distributor further comprises a fourth reduction oil pump (23), a fourth reduction oil discharge pipe (24), a fourth reduction return pipeline (25) and a fourth reduction discharge pipe (26), the fourth reduction oil discharge pipe (24) is connected with the inlet of the fourth reduction oil pump (23), the fourth reduction return pipeline (25), the fourth reduction return pipeline (10) and the fourth reduction discharge pipe (26) are connected with the outlet of the fourth reduction oil pump (23), the fourth reduction return pipeline (25) is connected with the first wax oil distribution pipe (16) through flanges, and a first heat exchanger (49) is arranged on the fourth reduction return pipeline (25).

6. The vacuum column for slurry-bed resid hydroprocessing units of claim 1, wherein: The first packing layer (27) is arranged in the first reduction zone (5), the second packing layer (28) is arranged in the second reduction zone (6), the third packing layer (29) is arranged in the third reduction zone (7), and the fourth packing layer (30) and the fifth packing layer (31) are arranged in the fourth reduction zone (8).

7. The vacuum column for slurry-bed resid hydroprocessing units of claim 6, characterized by: The fifth packing layer (31) is composed of corrugated packing and grid packing.

8. The vacuum column for slurry-bed resid hydroprocessing units of claim 6, characterized by: The first reduction distributor, the second reduction distributor and the third reduction distributor are further included, the first reduction distributor comprises a first reduction oil pump (32), a first reduction oil pipe (33), a first reduction upward return pipe (34), a first reduction upward return distribution pipe (35), a first reduction downward return pipe (36), a first reduction downward return distribution pipe (37) and a first reduction discharge pipe (38), the inlet of the first reduction oil pump (32) is communicated with the tower body (1) through the first reduction oil pipe (33), the first reduction upward return pipe (34), the first reduction downward return pipe (36) and the first reduction discharge pipe (38) are all communicated with the outlet of the first reduction oil pump (32), the first reduction upward return distribution pipe (35) is arranged above the first packing layer (27) and is flange-connected with the first reduction upward return pipe (34), the second heat exchanger (50) is arranged on the first reduction upward return pipe (34), the first reduction downward return distribution pipe (37) is arranged above the second packing layer (28) and is flange-connected with the first reduction downward return pipe (36), the second reduction distributor comprises a second reduction oil pump (39), a second reduction oil pipe (40), a second reduction downward return pipe (41), a second reduction downward return distribution pipe (42) and a second reduction discharge pipe (43), the inlet of the second reduction oil pump (39) is communicated with the tower body (1) through the second reduction oil pipe (40), the second reduction downward return pipe (41) and the second reduction discharge pipe (43) are all communicated with the outlet of the second reduction oil pump (39), the second reduction downward return distribution pipe (42) is arranged above the third packing layer (29) and is flange-connected with the second reduction downward return pipe (41), the third reduction distributor comprises a third reduction oil pump (44), a third reduction oil pipe (45), a third reduction downward return pipe (46), a third reduction downward return distribution pipe (47) and a third reduction discharge pipe (48), the inlet of the third reduction oil pump (44) is communicated with the tower body (1) through the third reduction oil pipe (45), the third reduction downward return pipe (46) and the third reduction discharge pipe (48) are all communicated with the outlet of the third reduction oil pump (44), the third reduction downward return distribution pipe (47) is arranged above the fourth packing layer (30) and is flange-connected with the third reduction downward return pipe (46).

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