Recovery device for methanol in methanol rectification non-condensable gas

Abstract

The utility model discloses a device for recovering methanol in methanol rectification non-condensable gas, which comprises an exhaust pipe and a water scrubber, a recooler is arranged between the exhaust pipe and the water scrubber, an inner cavity of the recooler is divided into a distribution cavity and a pre-cooling cavity by a distribution plate, a water inlet is arranged at the upper part of the distribution cavity, a water outlet is arranged at the bottom of the pre-cooling cavity, and a water outlet is arranged at the bottom of the pre-cooling cavity. A spiral cooling pipe is arranged in the pre-cooling cavity and is communicated with the lower part of the water washing tower through a communicating pipe, a plurality of groups of filler layers are arranged in the water washing tower at the upper part of the communicating pipe, and a spraying assembly is arranged in the water washing tower between two adjacent groups of filler layers; a circulating separation assembly communicated with the spraying assembly is arranged in the water washing tower at the lower part of the communicating pipe, the top of the water washing tower is provided with an exhaust port, the bottom of the water washing tower is provided with a liquid discharge pipe, and the end part of the liquid discharge pipe is connected with a recovery tank. The device not only can cool methanol gas carried in non-condensable gas, but also can improve the treatment capacity and treatment effect of the water scrubber, and realizes efficient recovery of methanol.

Description

Technical Field

[0001] The utility model belongs to the technical field of methanol production, and in particular relates to a device for recovering methanol from non-condensable gas in methanol rectification. Background Art

[0002] Methanol is a toxic organic chemical and a component of industrial alcohol. Industrially, it can be produced from carbon monoxide and hydrogen. Methanol serves as a new organic fuel, which is of great significance in today's oil-constrained society. Methanol is also used in plastics, fine chemicals, and other fields. The automotive industry, where methanol is consumed in significant quantities, is one of its most widely used applications. The production process of methanol mainly includes three steps: synthesis gas preparation, methanol synthesis and methanol distillation. Methanol distillation is to separate methanol from impurities mixed in it and extract pure methanol. At present, methanol distillation mainly adopts four-tower distillation technology, including pre-tower, pressure tower, atmospheric pressure tower and recovery tower. The main task is to remove light components such as dimethyl ether and other heavy components such as water and ethanol in crude methanol. Among them, the pre-tower distillation is that the crude methanol enters the pre-distillation tower to remove the residual dissolved gas (CO, CO2, H2, N2, CH4, multi-carbon alkanes, methyl formate, dimethyl ether) and other low-boiling point substances. However, during the operation of the pre-distillation tower, the light components will be removed from the crude methanol to meet the needs of the subsequent pressure tower and atmospheric pressure tower for refined methanol extraction. Among them, the light components include H2, CO, CO2 The methanol pre-distillation tower removes organic matter such as dimethyl ether and methyl formate, and the light components removed are non-condensable gases from the distillation. The non-condensable gases removed from the methanol pre-distillation tower carry a small amount of methanol gas. If the non-condensable gases are directly discharged, it will cause environmental pollution and methanol waste. In addition, the non-condensable gases contain combustibles, and direct discharge poses certain safety hazards. In the existing technology, in order to ensure safe production, the non-condensable gases are sent to a water scrubber and sprayed with desalted water to reduce the emission of combustibles and achieve methanol recovery. However, since the discharged non-condensable gases have a certain temperature, direct spraying with desalted water cannot effectively cool the non-condensable gases and cannot ensure the safety of discharge. In addition, the methanol cannot be thoroughly washed, resulting in a low methanol recovery rate. Therefore, it is objectively necessary to develop a methanol recovery device for methanol rectification non-condensable gases with a reasonable structure, good cooling effect, and high methanol recovery rate. Summary of the Invention

[0003] The utility model aims to provide a device for recovering methanol from non-condensable gas in methanol distillation, which has a reasonable structure, good cooling effect and high methanol recovery rate.

[0004] The purpose of the present utility model is achieved in this way, including an exhaust pipe and a water washing tower, a subcooler is arranged between the exhaust pipe and the water washing tower, the inner cavity of the subcooler is divided into a distribution cavity and a pre-cooling cavity by a distribution plate, a plurality of distribution holes are evenly distributed on the distribution plate, a water inlet is arranged on the upper part of the distribution cavity, a water outlet is arranged on the bottom of the pre-cooling cavity, a spiral cooling pipe is arranged inside the pre-cooling cavity, one end of the spiral cooling pipe is connected with the exhaust pipe, and the other end is connected with the lower part of the water washing tower through a connecting pipe, multiple groups of packing layers are arranged in the water washing tower at the upper part of the connecting pipe, a spray assembly is arranged in the water washing tower between two adjacent groups of packing layers, a circulation separation assembly connected with the spray assembly is arranged in the water washing tower at the lower part of the connecting pipe, an exhaust port is arranged at the top of the water washing tower, a drain pipe is arranged at the bottom, and the end of the drain pipe is connected with a recovery tank.

[0005] Compared with the existing technology, the advantages of this device are: first, a recooler is arranged between the exhaust pipe and the water scrubber, and the recooler can cool the non-condensable gas and reduce the temperature of the non-condensable gas entering the water scrubber. At the same time, the non-condensable gas is cooled by indirect cooling, and the methanol gas carried in the non-condensable gas can be cooled, reducing the processing burden of the subsequent water scrubber, which is conducive to improving the recovery rate of methanol; second, the structure of the water scrubber is optimized, and the spray assembly and filler assembly arranged in the water scrubber can increase the gas-liquid contact time between the desalted water and the non-condensable gas, improve the washing and separation efficiency of the non-condensable gas, achieve thorough washing and separation of the methanol gas, and improve the recovery rate of methanol. At the same time, the circulating separation assembly arranged can separate the methanol separated by washing, and avoid the desalted water carrying a large amount of methanol into the corresponding spray assembly during the recycling process. This not only improves the processing capacity and processing effect of the water scrubber, but also achieves efficient recovery of methanol. It has the advantages of simple structure and good cooling effect, and is easy to promote and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 It is a schematic diagram of the overall structure of the utility model;

[0007] Figure 2 for Figure 1 Enlarged view of part A;

[0008] In the figure: 1-exhaust pipe, 2-water washing tower, 21-packing assembly, 22-spray assembly, 23-exhaust port, 24-drain pipe, 25-separation plate, 26-partition, 27-overflow hole, 28-circulation pipe, 29-water supply pipe, 210-concentration detector, 211-down pipe, 212-buffer pipe, 3-subcooler, 31-distribution plate, 32-water inlet, 33-water outlet, 34-spiral cooling pipe, 35-drive motor, 36-first pulley, 37-second pulley, 38-first rotating joint, 39-second rotating joint, 310-drive shaft, 311-drive belt, 4-connecting pipe, 5-recovery tank, 6-final cooler, 61-upper mounting plate, 62-lower mounting plate, 63-down pipe, 64-cold air inlet, 65-cold air outlet, 66-discharge pipe, 67-anti-vortex plate. DETAILED DESCRIPTION

[0009] The present invention will be further described below in conjunction with the accompanying drawings, but the present invention is not limited in any way. Any changes or improvements made based on the teachings of the present invention shall fall within the scope of protection of the present invention.

[0010] like Figures 1-2 As shown, the utility model includes an exhaust pipe 1 and a water washing tower 2, a subcooler 3 is arranged between the exhaust pipe 1 and the water washing tower 2, the inner cavity of the subcooler 3 is divided into a distribution cavity and a pre-cooling cavity by a distribution plate 31, the distribution plate 31 is evenly provided with a plurality of distribution holes, the upper part of the distribution cavity is provided with a water inlet 32, the bottom of the pre-cooling cavity is provided with a water outlet 33, the interior of the pre-cooling cavity is provided with a spiral cooling pipe 34, one end of the spiral cooling pipe 34 is connected with the exhaust pipe 1, and the other end is connected with the lower part of the water washing tower 2 through a connecting pipe 4, a plurality of groups of packing layers 21 are provided in the water washing tower 2 at the upper part of the connecting pipe 4, a spray assembly 22 is provided in the water washing tower 2 between two adjacent groups of packing layers 21, a circulation separation assembly connected with the spray assembly 22 is provided in the water washing tower 2 at the lower part of the connecting pipe 4, an exhaust port 23 is provided at the top of the water washing tower 2, and a drain pipe 24 is provided at the bottom, and the end of the drain pipe 24 is connected to a recovery tank 5.

[0011] The working process of this device is: the non-condensable gas generated in the methanol pre-distillation tower first enters the spiral cooling tube 34 through the exhaust pipe 1. At this time, cold water is introduced into the distribution chamber through the water inlet 32. After the cold water enters the distribution chamber, it is evenly distributed through the distribution plate 31 and then flows evenly into the pre-cooling chamber through the distribution holes. The cold water flowing down can indirectly contact the non-condensable gas in the spiral cooling tube 34, thereby cooling the non-condensable gas. The cold water after absorbing heat is discharged from the water outlet 33, and the non-condensable gas after cooling enters the water washing tower 2. After the non-condensable gas enters the water washing tower 2, the desalted water is sprayed downwardly through the spray assembly 22. The spray assembly 22 is a structure used in the prior art, including a liquid inlet pipe, a nozzle and other structures. The desalted water flows downwardly in the water washing tower 2, and the non-condensable gas flows upwardly in the water washing tower 2. The condensed gas and the desalted water are in gas-liquid contact between the packing layer assembly 21. The packing layer assembly 21 is a structure in the prior art, including upper and lower grids and packing arranged between the grids. During the gas-liquid contact process, the desalted water can wash and separate the methanol gas carried in the non-condensable gas. The washed and separated methanol gas is dissolved in the desalted water and flows into the bottom of the water washing tower 2. After separation by the circulating separation assembly, the methanol solution with the required concentration is discharged from the drain pipe 24 into the recovery tank 5, and the desalted water with the concentration not meeting the requirements is returned to the spray assembly 22 for recycling. The non-condensable gas after washing and separation is discharged from the exhaust port 23 and directly enters the co-combustion system for treatment after adsorption treatment. This device can not only improve the processing capacity and processing effect of the water washing tower 2, but also achieve efficient recovery of methanol.

[0012] Furthermore, in order to achieve efficient cooling of the non-condensable gas, the spiral cooling tube 34 is divided into two groups arranged at intervals in the upper and lower parts. The external drive of the subcooler 3 drives the spiral cooling tube 34 to rotate. The driving mechanism drives the spiral cooling tube to rotate, which can improve the cooling effect of the cold sewage on the non-condensable gas. The driving mechanism includes a driving motor 35, a first pulley 36 and a second pulley 37. The driving motor 35 is a structure used in the prior art. The finished product can be directly purchased according to the power used. The inlet end of the spiral cooling tube 34 is rotatably connected to the exhaust pipe 1 through a first rotating joint 38, and the outlet end of the spiral cooling tube 34 is rotatably connected to the connecting pipe 4 through a second rotating joint 39. The first rotating structure 38 and the second rotating structure 39 are The form of the rotating pipe joint applicable in the prior art can be directly purchased according to the size of the pipe diameter used for the function. The driving motor 35 is installed on the outside of the subcooler 3. A transmission shaft 310 is installed on the output shaft of the driving motor 35. There are two first pulleys 36, and the two first pulleys 36 are installed on the transmission shaft 310 at intervals. There are two second pulleys 37, and the second pulleys 37 are installed on the inlet ends of the two groups of spiral cooling tubes 34. The two first pulleys 36 are connected to the corresponding second pulleys 37 through a transmission belt 311. When in use, the driving motor 35 drives the transmission shaft 310 to rotate. During the rotation of the transmission shaft 310, it can drive the two first pulleys 36 to rotate. During the rotation of the two first pulleys 36, The second pulley 37 can be driven to rotate by the corresponding transmission belt 311, and then the spiral cooling tube 34 can be driven to rotate in the pre-cooling chamber. The rotating spiral cooling tube 34 can be in uniform contact with the cold water, which is conducive to improving the cooling effect. Further, the circulating separation component includes a separation plate 25 and a partition 26. The separation plate 25 is horizontally installed in the water washing tower 2. A connecting hole is processed at the center of the separation plate 25. The partition 26 is vertically installed in the water washing tower 2 below the separation plate 25. An overflow hole 27 is provided between the partition 26 and the separation plate 25. A circulation pipe 28 connected to the spray assembly 22 is provided on the water washing tower 2 on one side of the partition 26. A circulation pump, a first valve and a water supply pipe 29 are sequentially provided on the circulation pipe 28. A water supply valve is installed on the water supply pipe 29, and a concentration detector 210 is provided on the water washing tower 2 on the other side of the partition 26. The concentration detector 210 is a structure used in the prior art and can be directly purchased as a finished product according to the requirements of use. The drain pipe 24 is provided on the water washing tower 2 below the concentration detector 210. A second valve is installed on the drain pipe 24. After washing and separation with desalted water, the methanol gas dissolves in the desalted water to form a methanol aqueous solution which is accumulated on the separation plate 25 and then flows into the bottom of the water washing tower 2 through the connecting hole. After the methanol aqueous solution falling into the water washing tower 2 is separated by the partition 26, the low-concentration methanol aqueous solution flows into the other side of the partition 26 through the overflow hole and returns to the spray assembly 22 through the circulation pipe 28 for recycling.If concentration detector 210 detects that the methanol-water solution meets the required concentration, the second valve on drain pipe 24 can be opened to drain the methanol-water solution in water scrubber 2 into recovery tank 5 through drain pipe 24. The water replenishment valve on water replenishment pipe 29 is then opened to replenish desalted water into circulation pipe 28. To improve the methanol recovery rate, a downpipe 211 is vertically installed at the bottom of the connecting hole, and a buffer pipe 212 is horizontally installed at the bottom of the downpipe 211. The methanol-water solution enters downpipe 211 and flows out through buffer pipe 212, which prolongs the downward flow time, prolongs the time for methanol to dissolve, and improves the methanol recovery rate.

[0013] Furthermore, in order to improve the cooling effect of the non-condensable gas and reduce the processing burden of the subsequent water washing tower, a final cooler 6 is provided on the connecting pipe 4. An upper mounting plate 61 and a lower mounting plate 62 are installed at intervals in the upper and lower parts of the final cooler 6. A plurality of downcomers 63 are evenly distributed and installed on the upper mounting plate 61 and the lower mounting plate 62. A cold air inlet 64 is provided at the bottom of one side of the final cooler 6 between the upper mounting plate 61 and the lower mounting plate 62, and a cold air outlet 65 is provided at the top of the other side. A liquid outlet pipe 66 connected to the recovery tank 5 is provided at the bottom of the final cooler 6, and a third valve is provided on the liquid outlet pipe 66. The non-condensable gas after the cooling treatment by the spiral cooling pipe 34 first enters the final cooler 6. After entering the final cooler 6, the non-condensable gas is blocked by the upper mounting plate 61 and then enters each downcomer 63. Under the action of gravity, the methanol gas in the non-condensable gas that has been cooled will cool down to form small droplets, and eventually flow into the bottom of the final cooler 6, and then be discharged into the recovery tank 5 through the liquid outlet pipe 66. During the sedimentation of the methanol gas, cold air can be passed into the final cooler 6 through the cold air inlet 64, and the cold air is used to cool the non-condensable gas again, thereby improving the cooling effect on the methanol gas. The cold air that absorbs heat is discharged from the cold air outlet 65, which is beneficial to improving the yield of methanol. Preferably, in order to improve the cooling effect, the downcomer 63 is a corrugated pipe. In order to avoid erosion and corrosion to the bottom of the final cooler 6 and to increase its service life, an anti-vortex plate 67 is provided at the bottom of the final cooler 6 on the upper side of the liquid outlet pipe 66. The anti-vortex plate 67 adopts the structure used in the prior art.

Claims

1. A device for recovering methanol from non-condensable gas in methanol distillation, comprising an exhaust pipe (1) and a water washing tower (2), characterized in that: A subcooler (3) is provided between the exhaust pipe (1) and the water scrubber (2). The inner cavity of the subcooler (3) is divided into a distribution cavity and a precooling cavity by a distribution plate (31). The distribution plate (31) is evenly provided with a plurality of distribution holes. The upper portion of the distribution cavity is provided with a water inlet (32). The bottom portion of the precooling cavity is provided with a water outlet (33). A spiral cooling pipe (34) is provided inside the precooling cavity. One end of the spiral cooling pipe (34) is connected to the exhaust pipe (1), and the other end is connected to the exhaust pipe (1) through a connecting pipe (4). The lower part of the water washing tower (2) is connected, and multiple groups of packing layers (21) are arranged in the water washing tower (2) above the connecting pipe (4), and a spray assembly (22) is arranged in the water washing tower (2) between two adjacent groups of packing layers (21). A circulating separation assembly connected to the spray assembly (22) is arranged in the water washing tower (2) below the connecting pipe (4), and an exhaust port (23) is arranged at the top of the water washing tower (2), and a drain pipe (24) is arranged at the bottom, and the end of the drain pipe (24) is connected to a recovery tank (5).

2. The device for recovering methanol from non-condensable gas in methanol distillation according to claim 1, characterized in that: The spiral cooling pipes (34) are arranged in two groups at intervals in the upper and lower parts, and the subcooler (3) is provided with a driving mechanism outside to drive the spiral cooling pipes (34) to rotate.

3. The device for recovering methanol from non-condensable gas in methanol rectification according to claim 2, characterized in that: The driving mechanism comprises a driving motor (35), a first pulley (36) and a second pulley (37); the inlet end of the spiral cooling tube (34) is rotationally connected to the exhaust pipe (1) via a first rotating joint (38); the outlet end of the spiral cooling tube (34) is rotationally connected to the connecting pipe (4) via a second rotating joint (39); the driving motor (35) is installed outside the subcooler (3); a transmission shaft (310) is installed on the output shaft of the driving motor (35); there are two first pulleys (36), and the two first pulleys (36) are installed on the transmission shaft (310) at intervals; there are two second pulleys (37), and the second pulleys (37) are installed on the inlet ends of the two groups of spiral cooling tubes (34); the two first pulleys (36) and the corresponding second pulleys (37) are transmission-connected via a transmission belt (311).

4. The device for recovering methanol from non-condensable gas in methanol rectification according to claim 1, characterized in that: The circulating separation component comprises a separation plate (25) and a partition (26). The separation plate (25) is horizontally installed in a water washing tower (2). A connecting hole is machined at the center of the separation plate (25). The partition (26) is vertically installed in the water washing tower (2) below the separation plate (25). An overflow hole (27) is provided between the partition (26) and the separation plate (25). A circulation pipe (28) communicating with the spray assembly (22) is provided on the water washing tower (2) on one side of the partition (26). A circulation pump, a first valve and a water supply pipe (29) are sequentially provided on the circulation pipe (28). The water supply pipe (29) is equipped with a water supply valve. A concentration detector (210) is provided on the water washing tower (2) on the other side of the partition (26). The drain pipe (24) is provided on the water washing tower (2) below the concentration detector (210). The drain pipe (24) is equipped with a second valve.

5. The device for recovering methanol from non-condensable gas in methanol rectification according to claim 4, characterized in that: A downpipe (211) is vertically installed at the bottom of the communication hole, and a buffer pipe (212) is horizontally installed at the bottom of the downpipe (211).

6. The device for recovering methanol from non-condensable gas in methanol rectification according to claim 1, characterized in that: The connecting pipe (4) 4 is provided with an end cooler (6), and an upper mounting plate (61) and a lower mounting plate (62) are installed at intervals in the upper and lower parts of the end cooler (6). A plurality of downcomers (63) are evenly distributed and installed on the upper mounting plate (61) and the lower mounting plate (62). A cold air inlet (64) is provided at the bottom of one side of the end cooler (6) between the upper mounting plate (61) and the lower mounting plate (62), and a cold air outlet (65) is provided at the top of the other side. A liquid outlet pipe (66) communicating with the recovery tank (5) is provided at the bottom of the end cooler (6), and a third valve is provided on the liquid outlet pipe (66).

7. The device for recovering methanol from non-condensable gas in methanol rectification according to claim 6, characterized in that: The downcomer (63) is a bellows.

8. The device for recovering methanol from non-condensable gas in methanol rectification according to claim 6, characterized in that: An anti-vortex plate (67) is provided at the bottom of the final cooler (6) on the upper side of the liquid outlet pipe (66).

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