A multi-stage purification device for preparing sodium methoxide

Abstract

The present invention discloses a multi-stage purification device for preparing sodium methoxide, which relates to the technical field of chemical equipment. The device comprises: a tower body, the tower body is provided with a liquid inlet, the lower part of the tower body is provided with an air inlet and an outlet, the upper part of the tower body is provided with an exhaust port and a reflux port; a filter is fixedly connected and connected to the liquid inlet, and is used for filtering the sodium methoxide solution; a plurality of tower plates are fixedly connected to the tower body at equal intervals, the tower plates are fixedly connected with overflow plates fixed to the tower body, the overflow plates on adjacent tower plates are arranged in a staggered manner, the upper limit of the tower plate is slidably connected with a plurality of float valves, and the float valves are provided with multi-component flow holes distributed at equal intervals. The present invention controls the area of ​​the flow diversion holes by arranging a plurality of diversion holes on the float valve, and indirectly controls the volume of bubbles formed after the steam enters the clear liquid, thereby increasing the contact area between the steam and the clear liquid, and improving the mass transfer efficiency between the steam and the clear liquid.

Description

Technical Field

[0001] The invention relates to the technical field of chemical equipment, and in particular to a multi-stage purification device for preparing sodium methoxide. Background Art

[0002] Sodium methoxide is an organic compound used in the pharmaceutical industry. It is usually prepared by mixing solid sodium hydroxide and methanol in a certain proportion, stirring and dissolving to remove solid impurities, and then injecting the clear liquid into a distillation tower. The plate distillation tower is used to remove the unreacted methanol in the clear liquid to obtain pure sodium methoxide.

[0003] In the existing plate distillation tower, when working, clear liquid (containing sodium methoxide and methanol) is flowed downward along the tower plate, so that the clear liquid accumulates to a certain thickness at the overflow weir, and then high-temperature steam passes through the float valve on the tower plate and performs mass transfer and heat exchange with the accumulated clear liquid. The high-temperature steam converts the methanol in the clear liquid into methanol vapor and drives it to rise together. In this way, the methanol in the clear liquid is gradually removed by the high-temperature steam to complete the purification of sodium methoxide. However, when the high-temperature steam passes through the float valve, the gap between the float valve and the tower plate is large, so that the bubbles formed by the high-temperature steam entering the clear liquid after passing through the float valve are large, and the contact area between the high-temperature steam and the clear liquid is small relative to the volume of the high-temperature steam, so that the mass transfer efficiency between the high-temperature steam and the clear liquid is low. Summary of the invention

[0004] The invention provides a multi-stage purification device for preparing sodium methoxide, so as to overcome the shortcomings of small contact area between gas phase and liquid phase and low mass transfer efficiency in the existing plate-type distillation tower.

[0005] The technical solution is: a multi-stage purification device for preparing sodium methoxide, comprising: a tower body, the tower body is provided with a liquid inlet, the lower part of the tower body is provided with an air inlet and an outlet, and the upper part of the tower body is provided with an exhaust port and a reflux port; a filter is fixedly connected to and connected to the liquid inlet, and is used for filtering the sodium methoxide solution; a plurality of tower plates are fixedly connected to the tower body at equal intervals, the tower plates are fixedly connected with overflow plates fixed to the tower body, the overflow plates on adjacent tower plates are staggered, the upper limit sliding connection of the tower plates is provided with a plurality of float valves, the float valve is provided with multi-group flow holes distributed at equal intervals, and in the direction from top to bottom, the area of ​​each group of the flow diversion holes increases in a step-like manner, and a plurality of leakage holes are provided on the upper side of the float valve.

[0006] Furthermore, a trumpet portion is provided on the lower side of the float valve.

[0007] Furthermore, it also includes: a number of stabilizing components equal to that of the float valve, the stabilizing components are arranged on adjacent tower plates near adjacent float valves, the stabilizing components are used to reduce the movement frequency of the float valve when subjected to air pressure fluctuations, the stabilizing components include: a mounting ring, fixedly connected to the tower plate, the mounting ring is slidably connected to the float valve, the mounting ring is provided with a lower groove portion, an upper groove portion and a protrusion portion, the protrusion portion is fixedly connected with a friction member, the friction member and the float valve are frictionally matched; an outer friction ring, fixedly connected to the upper side of the tower plate, the outer friction ring is located above the mounting ring, the float valve is limited and sealingly slidably connected with an inner friction ring, the inner friction ring and the outer friction ring are jointly fixed with a connecting member, and there is friction between the inner friction ring and the float valve.

[0008] Furthermore, the sum of the friction forces of the friction member and the inner friction ring on the float valve is smaller than the gravity of the float valve.

[0009] Furthermore, it also includes: extrusion pieces whose number is equal to the tower plates, which are arranged above the adjacent tower plates and are in contact with and cooperate with all the float valves on the adjacent tower plates, and the float valves and the adjacent extrusion pieces are fixedly connected with a traction rope.

[0010] Furthermore, it also includes: pressure measuring components whose number is equal to the tower plates, the pressure measuring components are arranged on the tower body near the tower plates, the pressure measuring components are used to detect the air pressure in the tower body, and the pressure measuring components include: a mounting basket, fixedly connected to the tower body, an airbag fixedly connected in the mounting basket; a fixed cylinder, fixedly connected to the mounting basket and connected to the adjacent airbag, a connecting rod sealed and slidably connected in the fixed cylinder.

[0011] Furthermore, a sealing ring is fixedly connected to the connecting rod, and friction exists between the sealing ring and the adjacent fixing tube.

[0012] Furthermore, the connecting rod is fixedly connected with a shielding member, and the shielding member is located above the adjacent tower plate.

[0013] Furthermore, it also includes: bifurcated pipes, the number of which is one less than the number of the tower plates, fixedly connected to the tower body, a pressure valve is arranged in the bifurcated pipe, and the two ends of the bifurcated pipe are respectively located on the upper and lower sides of the adjacent tower plates.

[0014] Furthermore, the bifurcated pipe is fixedly connected to and communicated with air supply pipes having a number equal to the float valves on a single tower plate, and one end of the air supply pipe is located in an adjacent float valve.

[0015] The beneficial effects produced by adopting the above technical scheme are as follows: the present invention controls the area of ​​the diverter holes by arranging a plurality of diverter holes on the float valve, and indirectly controls the volume of bubbles formed after the steam enters the clear liquid, thereby increasing the contact area between the steam and the clear liquid and improving the mass transfer efficiency between the steam and the clear liquid; by setting the area change of the diverter holes, the mass transfer time between the steam and the clear liquid is increased, thereby promoting the mass transfer between the steam and the clear liquid; the movement of the float valve is delayed by the friction part, thereby preventing the float valve from moving at the first time when the air pressure fluctuates, reducing unnecessary movements of the float valve, and thereby reducing the number of times the float valve is worn; all the float valves on the same tower plate are connected as a whole by the extrusion part, and the heights of all the float valves on the same tower plate are made consistent without affecting the disassembly and replacement of a single float valve, thereby ensuring the mass transfer efficiency between the steam and the clear liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0017] Figure 2 It is a schematic diagram of the three-dimensional structure of the tower body, overflow plate and bifurcated pipe of the present invention;

[0018] Figure 3 It is a three-dimensional structural schematic diagram of the tower body, tower plate and overflow plate of the present invention;

[0019] Figure 4 It is a schematic diagram of the three-dimensional structure of the tower plate, overflow plate and float valve of the present invention;

[0020] Figure 5 It is a three-dimensional structural schematic diagram of the tower plate, the float valve and the mounting ring of the present invention;

[0021] Figure 6 It is a three-dimensional structural cross-sectional view of the float valve, the mounting ring and the connecting piece of the present invention;

[0022] Figure 7 It is a three-dimensional structural cross-sectional view of the outer friction ring, the inner friction ring and the connecting piece of the present invention;

[0023] Figure 8 It is a three-dimensional structural schematic diagram of the float valve, extrusion member and traction rope of the present invention;

[0024] Fig. 9 It is a three-dimensional structural schematic diagram of the mounting basket, the fixing cylinder and the shielding member of the present invention;

[0025] Fig.10 It is a three-dimensional structural cross-sectional view of the mounting basket and the fixing cylinder of the present invention;

[0026] Fig.11 It is a three-dimensional structural schematic diagram of the float valve, bifurcated pipe and air supply pipe of the present invention.

[0027] The markings of the components in the accompanying drawings are as follows: 1-tower body, 101-liquid inlet, 102-air inlet, 103-outlet, 104-exhaust port, 105-reflux port, 2-filter, 3-tower plate, 4-overflow plate, 5-float valve, 501-diverter hole, 502-leakage hole, 503-trumpet part, 6-mounting ring, 601-lower groove part, 602-upper groove part, 603-protrusion, 7-friction part, 8-outer friction ring, 9-inner friction ring, 10-connecting part, 11-extrusion part, 12-traction rope, 13-mounting basket, 14-air bag, 15-fixing cylinder, 16-connecting rod, 17-sealing ring, 18-shielding part, 19-forked pipe, 20-pressure valve, 21-air supply pipe. DETAILED DESCRIPTION

[0028] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings.

[0029] A multi-stage purification device for preparing sodium methoxide, see Figure 1-Figure 6 , comprising: a tower body 1, the tower body 1 is provided with a liquid inlet 101, the lower part of the tower body 1 is provided with an air inlet 102 and an outlet 103, the upper part of the tower body 1 is provided with an exhaust port 104 and a reflux port 105; a filter 2, fixedly connected and connected to the liquid inlet 101, for filtering the sodium methoxide solution; a plurality of tower plates 3, fixedly connected to the tower body 1 at equal intervals, the tower plates 3 are fixedly connected with overflow plates 4 fixed to the tower body 1, the overflow plates 4 on adjacent tower plates 3 are staggered, the upper limit sliding connection of the tower plates 3 is provided with a plurality of float valves 5, the float valve 5 is provided with multi-group flow holes 501 distributed at equal intervals, and in the direction from top to bottom, the area of ​​each group of flow holes 501 increases in a step-by-step manner, and a plurality of leakage holes 502 are provided on the upper side of the float valve 5; a trumpet portion 503 is provided on the lower side of the float valve 5.

[0030] The air inlet 102 is connected to an external reboiler, which is used to heat the clear liquid and generate methanol vapor by utilizing the different melting points of methanol and sodium methoxide. The air inlet 102 is used to inject methanol vapor into the tower body 1; the outlet 103 is also connected to an external reboiler, and is used to transport the bottom liquid accumulated in the tower kettle (the bottom liquid is a methanol solution of sodium methoxide, and the concentration of sodium methoxide in the bottom liquid is greater than the concentration of sodium methoxide in the clear liquid) to the reboiler. The reboiler utilizes the different boiling points of methanol and sodium methoxide to heat part of the methanol in the bottom liquid. The methanol vapor is converted back into methanol vapor (in order to maintain the flow rate of the vapor), and the methanol vapor is input into the air inlet 102, and then the remaining bottom liquid is discharged and waits to be injected into the tower body 1 through the liquid inlet 101 again; the exhaust port 104 is connected to the external condenser, and the condenser is used to condense the vapor into liquid and recover part of the methanol; the reflux port 105 is connected to the condenser, and is used to reflux part of the methanol solution into the tower to maintain the gas-liquid balance and separation efficiency in the distillation tower; a manhole is provided on the tower body 1 for maintenance and installation.

[0031] In the above scheme, the problem of small contact area between steam and clear liquid passing through the float valve 5 is solved; the scheme controls the area of ​​the diverter holes 501 by setting a plurality of diverter holes 501 on the float valve 5, and indirectly controls the volume of bubbles formed after the steam enters the clear liquid; the staggered overflow plates 4 are respectively located at the front and rear sides of the tower body 1; the upper side of the tower plate 3, the overflow plate 4 and the tower body 1 form an overflow weir, and a downflow channel is formed between the side of the overflow plate 4 away from the adjacent tower plate 3 and the tower body 1, and the lower side of the overflow plate 4 can be slightly lower than the upper side of the adjacent overflow plate 4 on its lower side, so that the liquid level of the clear liquid accumulated on the tower plate 3 is submerged above the lower side of the overflow plate 4, and the clear liquid is used to flow the downflow channel. Blocking prevents steam from rising through the downcomer flow channel; each group of diversion holes 501 includes a plurality of diversion holes 501 distributed in an annular manner, and two adjacent groups of diversion holes 501 can be staggered to improve the uniformity of steam distribution in the clear liquid; in the top-down direction, the area of ​​each group of diversion holes 501 gradually increases, which can cause the steam flow in the bottom-up direction to gradually decrease, increase the mass transfer time between steam and clear liquid, and further promote the mass transfer between steam and clear liquid; the leakage hole 502 is used to prevent the float valve 5 from completely blocking the tower plate 3, to prevent liquid from still accumulating in the overflow weir after the distillation tower is finished working; the trumpet part 503 is used to guide the steam into the float valve 5.

[0032] See also Figure 5-Figure 7, and also includes: a number of stabilizing components equal to the float valve 5, the stabilizing components are arranged on adjacent tower plates 3 near adjacent float valves 5, the stabilizing components are used to reduce the movement frequency of the float valve 5 when subjected to air pressure fluctuations, the stabilizing components include: a mounting ring 6, fixedly connected to the tower plate 3, the mounting ring 6 is slidably connected to the float valve 5, a lower groove portion 601, an upper groove portion 602 and a protrusion 603 are provided on the mounting ring 6, the protrusion 603 is fixedly connected with a friction member 7, and the friction member 7 and the float valve 5 are frictionally matched; an outer friction ring 8, fixedly connected to the upper side of the tower plate 3, the outer friction ring 8 is located above the mounting ring 6, the float valve 5 is limited and sealed and slidably connected with an inner friction ring 9, the inner friction ring 9 and the outer friction ring 8 are jointly fixedly connected with a connecting member 10, and there is friction between the inner friction ring 9 and the float valve 5; the sum of the friction forces of the friction member 7 and the inner friction ring 9 on the float valve 5 is less than the gravity of the float valve 5.

[0033] In the above scheme, the problem of unnecessary wear and tear caused by the floating valve 5 moving up and down following the air pressure when the air pressure in the tower body 1 fluctuates is solved; in this scheme, the friction member 7 is used to delay the movement of the floating valve 5, thereby preventing the floating valve 5 from moving at the first time when the air pressure fluctuates, reducing unnecessary movements of the floating valve 5, and thus reducing the number of times the floating valve 5 is worn; a filter screen coplanar with the peripheral side of the floating valve 5 can be set on the diversion hole 501 to maintain the shape of the friction member 7 and the inner friction ring 9; the friction member 7 is made of high-temperature resistant elastic rubber material, and Initially (i.e., in the state shown in the figure), the inner side of the friction member 7 is in an extruded state, and the outer side of the friction member 7 is embedded in the protrusion 603; the connecting member 10 is made of elastic material, and can be deformed into a truncated cone shape under the action of external tension; initially, the steam on the lower side of the float valve 5 flows through the leakage hole 502, and as the float valve 5 slides relative to the inner friction ring 9, the diverter holes 501 at different heights on the float valve 5 sequentially pass over the inner friction ring 9, and at this time, the steam on the lower side of the float valve 5 flows through the leakage hole 502 and the diverter hole 501 located above the inner friction ring 9.

[0034] The specific working principle of the above scheme for slowing down the wear of the float valve 5 is as follows: when the air intake amount at the lower side of the float valve 5 is greater than the exhaust amount of the float valve 5 per unit time, the air pressure at the lower side of the float valve 5 increases, and the thrust of the air pressure at the lower side of the float valve 5 on the float valve 5 is greater than the weight of the float valve 5 itself, so that the float valve 5 has a tendency to move upward. At this time, due to the friction force of the deformation of the friction member 7 on the float valve 5, the float valve 5 will not move at the first time, until the force given by the air pressure to the float valve 5 is greater than the friction force of the friction member 7 on the float valve 5, the float valve 5 moves upward and drives the inner side of the friction member 7 to move upward, so that the inner side of the friction member 7 enters the upper groove portion 602. At this time, the middle part of the friction member 7 is stretched, and the inner side of the friction member 7 loses extrusion, that is, the friction force of the friction member 7 on the float valve 5 is reduced. At this time, the float valve 5 moves up a certain height according to the change of air pressure until the air intake amount at the lower side of the float valve 5 is equal to the exhaust amount of the float valve 5 again, and the float valve 5 stops moving.

[0035] While the float valve 5 drives the inner side of the friction member 7 to move upward, the float valve 5 drives the inner friction ring 9 to move upward, and the inner friction ring 9 pulls the connecting member 10 until the inner side of the friction member 7 enters the upper groove portion 602, and the inner friction ring 9 pulls the connecting member 10 to a flat state. At this time, the inner friction ring 9 stops moving upward under the traction of the connecting member 10, and then the float valve 5 moves upward relative to the inner friction ring 9, so that the exhaust area of ​​the float valve 5 is increased, until the exhaust volume of the float valve 5 is equal to the intake volume on the lower side of the float valve 5, the float valve 5 stops moving, and at this time, the friction member 7 drives the float valve by friction under the action of the central reset. 5 moves downward, the float valve 5 drives the inner friction ring 9 to move downward, and the inner friction ring 9 drives the connecting member 10 to become the wrinkled state again. When the friction member 7 is reset, the inner friction ring 9 is reset relative to the outer friction ring 8. When the air pressure at the lower side of the float valve 5 is reduced, the above steps are repeated in reverse. During the above reset process, the exhaust area of ​​the float valve 5 remains unchanged. At the same time, by changing the extrusion state of the friction member 7, the friction force between the friction member 7 and the float valve 5 is changed. While delaying the movement timing of the float valve 5, the resistance of the float valve 5 when moving is reduced, so that the float valve 5 can adjust the exhaust area of ​​the float valve 5 according to the air pressure.

[0036] See also Figure 4 and Figure 8 , and also includes: extrusion pieces 11, the number of which is equal to the tower plates 3, which are arranged above the adjacent tower plates 3 and contact and cooperate with all the float valves 5 on the adjacent tower plates 3. The float valves 5 and the adjacent extrusion pieces 11 are jointly fixed with a traction rope 12.

[0037] In the above scheme, the problem that the existing float valve 5 is easily stuck after long-term use, resulting in different heights of the float valves 5 at different locations on the tower plate 3, that is, different flow rates of steam discharged from the float valve 5, reducing the efficiency of mass transfer between steam and clear liquid; in this scheme, all the float valves 5 on the same tower plate 3 are connected as a whole by an extrusion piece 11, and the heights of all the float valves 5 on the same tower plate 3 are made consistent without affecting the disassembly and replacement of a single float valve 5, thereby ensuring the efficiency of mass transfer between steam and clear liquid; the shape of the extrusion piece 11 can be changed according to actual conditions, as long as It can contact all the float valves 5 on the same tower plate 3 without affecting the rising of steam; the traction rope 12 can be a thin steel wire rope, etc.; the weight of the extrusion 11 can be adjusted according to actual conditions, specifically: the weight of the extrusion 11 is dispersed on the float valve 5, so that the air pressure on the lower side of the float valve 5 increases, and at the same time, the increase in air pressure increases the flow rate of steam discharged from the diversion hole 501. If the steam flow rate is too large, it will aggravate the entrainment of mist and foam, affecting the purity of the product. Therefore, when adjusting the weight of the extrusion 11, the subsequent entrainment of mist and foam should be prevented.

[0038] See also Figure 4 , Fig. 9 and Fig.10, and also includes: pressure measuring components whose number is equal to the tower plates 3, the pressure measuring components are arranged on the tower body 1 near the tower plates 3, the pressure measuring components are used to detect the air pressure in the tower body 1, and the pressure measuring components include: a mounting basket 13, which is fixed to the tower body 1, and an air bag 14 is fixed in the mounting basket 13; a fixed cylinder 15, which is fixed to the mounting basket 13 and communicated with the adjacent air bag 14, and a connecting rod 16 is sealed and slidably connected in the fixed cylinder 15; a sealing ring 17 is fixed to the connecting rod 16, and there is friction between the sealing ring 17 and the adjacent fixed cylinder 15; a shielding member 18 is fixed to the connecting rod 16, and the shielding member 18 is located above the adjacent tower plate 3.

[0039] In the above scheme, the problem of mist entrainment caused by increased steam flow rate is solved; this scheme determines the size of the steam flow rate by detecting the air pressure. When the steam flow rate is too large to cause mist entrainment, the shielding member 18 is used to absorb part of the kinetic energy of the bubbles, thereby alleviating the mist entrainment (when the steam flow rate exceeds the design limit, the kinetic energy of the steam is too large, and the high-speed rising steam exerts a strong shear force and impact force on the liquid on the tower plate 3, breaking the liquid into small droplets and entraining them to move upward); gas is stored in the airbag 14, and the air pressure in the airbag 14 is slightly lower than the maximum air pressure allowed in the tower body 1 (that is, at the maximum air pressure, the exhaust area of ​​the float valve 5 reaches the maximum, and at this time the steam flow rate cannot cause mist entrainment), so that the air in the tower body 1 When the pressure reaches the maximum pressure, a pressure difference is formed between the air pressure in the tower body 1 and the air pressure in the airbag 14, so that the volume of the airbag 14 is reduced; the mounting basket 13 is composed of two upper and lower rings and a plurality of cylinders connecting the two rings as a whole, which is used to expose the airbag 14 in the mounting basket 13 to the inside of the tower body 1; the friction between the sealing ring 17 and the fixed cylinder 15 accumulates force for the movement of the connecting rod 16, and the difference between the static friction force and the dynamic friction force of the sealing ring 17 on the fixed cylinder 15 is used to enable the connecting rod 16 to move up quickly; a hole is provided on the shielding member 18, and the shielding member 18 is not in contact with the float valve 5, so that the movement resistance of the shielding member 18 is minimized, and when the bubble passes through the shielding member 18, the shielding member 18 absorbs part of the kinetic energy of the bubble, thereby alleviating the entrainment of mist.

[0040] See also Figure 1-Figure 3 and Fig.11 , and also includes: a bifurcated pipe 19, the number of which is one less than the number of tower plates 3, fixedly connected to the tower body 1, a pressure valve 20 is arranged in the bifurcated pipe 19, and the two ends of the bifurcated pipe 19 are respectively located on the upper and lower sides of the adjacent tower plate 3; the bifurcated pipe 19 is fixedly connected and connected to an air supply pipe 21 whose number is equal to the float valve 5 on a single tower plate 3, and one end of the air supply pipe 21 is located in the adjacent float valve 5.

[0041] In the above scheme, the flow path of steam is changed by the bifurcated pipe 19, thereby reducing the flow rate of steam when it is discharged from the diverter hole 501; the communication pressure of the pressure valve 20 is set to be greater than the maximum pressure allowed in the tower body 1, so as to disperse the steam when the steam pressure in the tower body 1 is too high, thereby reducing the flow rate of the steam discharged from the diverter hole 501, and at the same time reducing the probability of flooding (i.e., the steam between two adjacent tower plates 3 cannot be discharged in time, resulting in excessive steam pressure, hindering the descent of the clear liquid in the downcomer flow channel, and causing the clear liquid to accumulate on the upper tower plate 3); when the steam pressure is too high, the bifurcated pipe 19 is opened to guide the steam between two adjacent tower plates 3 to the vicinity of the upper float valve 5, which can not only relieve the pressure of the steam between the two tower plates 3 and reduce the probability of flooding, but also give priority to the use of part of the steam during the pressure relief to ensure the concentration of methanol in the steam.

[0042] Finally, it should be noted that: Obviously, the above embodiments are only examples for clearly explaining the present application, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the scope of protection of this application.

Claims

1. A multi-stage purification device for preparing sodium methoxide, characterized in that it comprises: A tower body (1), wherein the tower body (1) is provided with a liquid inlet (101), the lower part of the tower body (1) is provided with an air inlet (102) and an outlet (103), and the upper part of the tower body (1) is provided with an air outlet (104) and a reflux outlet (105); A filter (2) fixedly connected to and connected to the liquid inlet (101) and used for filtering the sodium methoxide solution; A plurality of tower plates (3) are fixedly connected to the tower body (1) at equal intervals, the tower plates (3) are fixedly connected to overflow plates (4) fixedly connected to the tower body (1), the overflow plates (4) on adjacent tower plates (3) are arranged in a staggered manner, the tower plates (3) are slidably connected to the upper limit position with a plurality of float valves (5), the float valves (5) are provided with multiple groups of flow holes (501) distributed at equal intervals, and in a direction from top to bottom, the area of ​​each group of the flow holes (501) increases in a step-like manner, and the upper side of the float valve (5) is provided with a plurality of leakage holes (502); Also includes: The number of stabilizing components is equal to that of the floating valves (5), and the stabilizing components are arranged on adjacent tower plates (3) and close to adjacent floating valves (5). The stabilizing components are used to reduce the movement frequency of the floating valves (5) when subjected to air pressure fluctuations. The stabilizing components include: A mounting ring (6) is fixedly connected to the tower plate (3); the mounting ring (6) is slidably connected to the float valve (5); a lower groove portion (601), an upper groove portion (602) and a protrusion portion (603) are provided on the mounting ring (6); a friction member (7) is fixedly connected to the protrusion portion (603); the friction member (7) is made of high temperature resistant elastic rubber material; the friction member (7) and the float valve (5) are frictionally matched; An outer friction ring (8) is fixedly connected to the upper side of the tower plate (3). The outer friction ring (8) is located above the mounting ring (6). The float valve (5) is limited and sealed and slidably connected to an inner friction ring (9). The inner friction ring (9) and the outer friction ring (8) are fixedly connected to a connecting piece (10). The connecting piece (10) is made of elastic material and can be deformed into a truncated cone shape under the action of external tension. Friction exists between the inner friction ring (9) and the float valve (5); The sum of the friction forces of the friction member (7) and the inner friction ring (9) on the float valve (5) is smaller than the gravity of the float valve (5).

2. A multi-stage purification device for preparing sodium methoxide according to claim 1, characterized in that: A trumpet portion (503) is provided on the lower side of the float valve (5).

3. A multi-stage purification device for preparing sodium methoxide according to claim 1, characterized in that, include: The extrusion pieces (11) having the same number as the tower plates (3) are arranged above the adjacent tower plates (3) and are in contact with and cooperate with all the float valves (5) on the adjacent tower plates (3). The float valves (5) and the adjacent extrusion pieces (11) are fixedly connected with a traction rope (12).

4. A multi-stage purification device for preparing sodium methoxide according to claim 3, characterized in that, include: The number of pressure measuring assemblies is equal to the number of the tower plates (3), the pressure measuring assemblies are arranged on the tower body (1) at a position close to the tower plates (3), the pressure measuring assemblies are used to detect the air pressure in the tower body (1), and the pressure measuring assemblies include: A mounting basket (13) is fixedly connected to the tower body (1), and an air bag (14) is fixedly connected to the mounting basket (13); The fixed cylinder (15) is fixedly connected to the mounting basket (13) and is in communication with the adjacent airbag (14). A connecting rod (16) is sealingly and slidably connected inside the fixed cylinder (15).

5. A multi-stage purification device for preparing sodium methoxide according to claim 4, characterized in that: A sealing ring (17) is fixedly connected to the connecting rod (16), and friction exists between the sealing ring (17) and the adjacent fixing cylinder (15).

6. A multi-stage purification device for preparing sodium methoxide according to claim 5, characterized in that: The connecting rod (16) is fixedly connected with a shielding member (18), and the shielding member (18) is located above the adjacent tower plate (3).

7. A multi-stage purification device for preparing sodium methoxide according to claim 6, characterized in that, include: The number of bifurcated pipes (19) is one less than the number of the tower plates (3), and is fixedly connected to the tower body (1). A pressure valve (20) is arranged in the bifurcated pipe (19). The two ends of the bifurcated pipe (19) are respectively located on the upper and lower sides of adjacent tower plates (3).

8. A multi-stage purification device for preparing sodium methoxide according to claim 7, characterized in that: The branch pipe (19) is fixedly connected to and communicated with air supply pipes (21) having the same number as the float valves (5) on a single tower plate (3), and one end of the air supply pipe (21) is located inside an adjacent float valve (5).

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