Dropping device in metronidazole production

Abstract

The utility model discloses a dropping device in metronidazole production, which comprises a dropping unit, a driving unit, a reaction unit, a stirring unit and the like, a third space between a vertical rod of the stirring unit and a dropping pipe is filled with cooling water, and the whole dropping pipe is immersed in the cooling water to ensure that an acetaldehyde solution is continuously cooled in the dropping process; the first space is filled with cooling water, so that acetaldehyde which does not react in time and is volatilized drips again after being condensed in time, and the utilization rate of acetaldehyde is increased; an exchange area is arranged at the intersection of the vertical rod and the first space, so that the flowability of cooling water is realized, and the cooling effect is improved; the liquid outlet holes are formed in the cross rod, so that an acetaldehyde solution is dispersed in reaction liquid in time while being stirred, the contact area of the acetaldehyde solution and the reaction liquid is increased, rapid reaction is achieved, and acetaldehyde volatilization caused by local overheating due to the fact that the acetaldehyde solution is directly dripped into the reaction liquid is avoided; a common vertical rod is arranged, and simultaneous stirring of the dropwise adding unit and the reaction unit can be realized only by using one set of driving unit, so that the equipment cost is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of metronidazole production, especially to the dropping device in metronidazole production. BACKGROUND

[0002] Metronidazole is a nitroimidazole antibacterial drug, which is widely used in clinical applications, mainly used for preventing and treating infections caused by anaerobic bacteria. In the industrial production process of metronidazole, acetaldehyde needs to be added dropwise into the reactor, and acetaldehyde is volatile, so it is necessary to control the low temperature of the added acetaldehyde during the dropping process to avoid the volatilization of acetaldehyde due to the local temperature rise during the dropping process, so that the acetaldehyde cannot fully react with the raw materials to be reacted.

[0003] In order to solve the problem of volatilization of acetaldehyde during the dropping process, patent CN209271399U discloses a kind of acetaldehyde negative pressure dropping device in metronidazole production, including reaction kettle, dropping funnel and dropping device, wherein the dropping device is the cylinder with upper end closed and lower end open, exhaust pipe with vacuum valve is arranged on top wall, and side wall is provided with circulation hole;The dropping liquid pipe of dropping funnel penetrates into the top wall of dropping device to the bottom of dropping device;The upper end opening connection of dropping device is sealed;The dropping device is inserted into the reaction kettle along the kettle wall;Cooling pipe is built-in in the dropping device.The dropping device of the patent adopts semi-closed design and combines cooler, acetaldehyde vapor can be fully utilized, and the utilization rate of acetaldehyde is improved.But the cooling pipe with spiral structure in the patent is used to cool acetaldehyde during the dropping process, and the contact area of the spiral structure with the pipeline for dropping acetaldehyde is limited, so the cooling effect is low.

[0004] Patent CN213254323U also discloses a kind of acetaldehyde negative pressure dropping device in metronidazole production, including cylinder, liquid storage bottle and dropping bottle, wherein the top of cylinder is fixedly connected with vertical plate, and the right side of vertical plate is fixedly connected with annular plate, the inner wall of annular plate is movably connected with the bottom surface of dropping bottle, the bottom of dropping bottle is communicated with dropping pipe, the right side of the top of cylinder inner wall is fixedly connected with cooling cylinder, the bottom end of dropping pipe penetrates cylinder and cooling cylinder in sequence and extends to the outside of cooling cylinder, and the top of the left side of cylinder is fixedly connected with water tank.The dropping device of the patent, the bottom of dropping bottle is communicated with dropping pipe, cooling cylinder is arranged around dropping pipe, acetaldehyde in dropping pipe is cooled by injecting cooling water into cooling cylinder, local overheating is prevented, volatilization of acetaldehyde solution is reduced, utilization rate of acetaldehyde solution is improved, and stirring mechanism is used to stir acetaldehyde solution to prevent acetaldehyde solution from stratifying.The patent sets cooling pipe around acetaldehyde dropping pipeline and fills cooling water in cooling pipe, so that acetaldehyde pipeline is completely in cooling water in cooling cylinder, and the cooling effect of acetaldehyde is better than that of spiral structure in patent CN209271399U.

[0005] But the patent CN213254323U, the cooling of the added acetaldehyde solution is only limited to the process of adding acetaldehyde, when acetaldehyde is dropped from the dropping tube, it is affected by the temperature in the reaction cylinder and volatilizes again, then part of the acetaldehyde will volatilize to the inner wall of the cylinder and is not easy to enter the reaction liquid below to react, which reduces the utilization rate of acetaldehyde. At the same time, after acetaldehyde is dropped from the dropping tube, it is directly dropped into the reaction liquid below, the dropped acetaldehyde and the reaction liquid only contact in a local part, although the stirring unit is arranged to stir the reaction liquid, but the dropped acetaldehyde and the reaction liquid still have a local reaction time, which also causes the local temperature to be too high to cause the unreacted acetaldehyde to volatilize, resulting in the reduction of the utilization rate of acetaldehyde. In addition, the patent CN213254323U adopts two sets of stirring mechanisms, and two motors are arranged to stir the reaction cylinder and the acetaldehyde solution storage bottle respectively, and the structure cost is high. SUMMARY

[0006] The utility model discloses a drop adding device for metronidazole production, solve the problem that acetaldehyde is volatilized due to local overheating in the process of adding and in the reaction unit, and improve the utilization rate of acetaldehyde.

[0007] The utility model discloses a drop adding device for metronidazole production, solve the problem that acetaldehyde is volatilized due to local overheating in the process of adding and in the reaction unit, and improve the utilization rate of acetaldehyde.

[0008] The reaction unit is flat as a whole, that is, the length in the horizontal direction is greater than the height of the reaction unit, and the main purpose is to reduce the liquid pressure in the reaction unit under the condition of ensuring the volume of the whole reaction unit.

[0009] A first feed inlet is arranged on one side of the upper portion of the reaction unit, and the reaction raw material is poured into the reaction unit. A discharge port is arranged at the lowermost portion of the reaction unit, and a discharge valve is arranged at the discharge port for discharging the materials in the reaction unit after the reaction is completed. The bottom of the reaction unit is arranged in an inclined manner, and the discharge port is the lowest point, so that the materials in the reactor can be discharged completely by gravity after the reaction is completed.

[0010] The first stirring is arranged inside the reaction unit, and comprises a vertical rod and a plurality of horizontal rods arranged on both sides of the vertical rod. The horizontal rods are arranged above and below the vertical rod, preferably four horizontal rods in total. One end of the horizontal rod is connected to the vertical rod, and the other end is close to the inner wall of the reaction unit, ensuring the stirring effect on the liquid in the reaction unit. The horizontal rods and the lower end of the vertical rod are in communication with each other, and a plurality of liquid outlet holes are arranged at the bottom of the horizontal rods. A hollow section is arranged in the vertical rod between the horizontal rods at the highest position and the horizontal rods at the lowest position. The lower end of the vertical rod is at the same horizontal plane as the bottom surface of the horizontal rods at the lowest position, so that the liquid entering the hollow section at the lower end of the vertical rod can flow out of the liquid outlet holes on the horizontal rods at the lowest position. A one-way valve is arranged at the communication position of the horizontal rod and the vertical rod, allowing the liquid to flow from one side of the vertical rod to the inside of the horizontal rod, and preventing the liquid in the horizontal rod from flowing into the vertical rod.

[0011] A first limiter is arranged on the inner side wall of the reaction unit above the first feed port, for controlling the liquid level in the reactor. When the liquid level reaches the first limiter during the pouring of the reaction liquid into the reactor through the first feed port, the external control system controls the first feed port to stop pouring. The position of the first limiter is lower than the height of the first feed port, but higher than the height of the highest horizontal rod.

[0012] The one-way valves at the connection positions of the horizontal rods and the vertical rods can be controlled individually by the external control system, i.e., the liquid in the lower end of the vertical rod can be selected to flow out through the liquid outlet holes below which horizontal rod by controlling the opening or closing of the one-way valves. For example, when the reaction liquid is less and the liquid surface is lower than the highest horizontal rod, the two one-way valves on the highest horizontal rod can be closed to prevent the liquid in the vertical rod from flowing out of the highest horizontal rod, thereby avoiding the situation that the dripped liquid does not directly enter the inside of the reaction liquid after flowing out of the liquid outlet holes, and reducing the mixing effect.

[0013] A first space is arranged at the top of the reaction unit, and a cooling liquid (such as cooling water) is introduced into the first space through the external control system. At this time, the top of the entire reaction unit is in a cooling state. When part of the unreacted acetaldehyde solution in the reaction unit volatilizes to the lower surface of the top of the reaction unit, the volatilized acetaldehyde is condensed due to the cooling effect of the top of the reaction unit, and then falls to the reaction liquid below for further reaction, thereby improving the utilization rate of acetaldehyde.

[0014] The middle vertical rod of the first stirring unit penetrates the top of the reaction unit upward and continues to extend upward to below the upper dropping unit. A driving unit is arranged between the dropping unit and the reaction unit, and the driving unit is composed of horizontal driving and vertical driving. A support leg is arranged on the top surface of the reaction unit to support the middle driving unit. The driving unit mainly includes a motor, a driving rod and a bevel gear. The bevel gear includes a first bevel gear arranged on the vertical rod between the dropping unit and the reaction unit and a second bevel gear arranged at one end of the driving rod close to the vertical rod and driven by the first bevel gear. The other end of the driving rod is connected with the motor. The rotation of the driving rod is driven by the movement of the motor, and then the first bevel gear is driven to rotate. The rotation of the first bevel gear and the second bevel gear converts the horizontal rotation into the vertical rotation, and then drives the vertical rod to rotate.

[0015] The dropping unit is composed of an outer wall and an inner cavity, and a second space is formed between the outer wall and the inner cavity. The upward extending vertical rod penetrates the outer wall at the bottom of the dropping unit to reach the bottom of the inner cavity, and the bottom of the inner cavity is connected with the top end of the vertical rod through a support column. The support column serves to support the entire inner cavity, and the top end of the support column and the vertical rod are connected through a first rotating shaft. The vertical rod can rotate relative to the support column through the first rotating shaft. A second rotating shaft is arranged at the connection between the vertical rod and the outer wall of the dropping unit, and the vertical rod can rotate relative to the outer wall through the second rotating shaft.

[0016] Symmetrical bent stirring rods are arranged on the vertical rod between the first rotating shaft and the second rotating shaft and located in the second space. A hollow area is arranged on the top plate of the inner cavity, and a vertical stirring blade is arranged at the front end of the bent stirring rod. The stirring blade enters the inner part of the inner cavity of the dropping unit through the hollow area on the top plate. When the vertical rod rotates, the vertical rod drives the stirring rod to rotate, and then the stirring blade rotates along the annular hollow area on the top plate of the inner cavity, so that the solution in the inner cavity of the dropping unit is stirred, and the stratification phenomenon of the acetaldehyde solution caused by long-term standing is avoided.

[0017] A second feeding port is arranged directly above the outer wall of the dropping unit. The second feeding port is used for feeding acetaldehyde solution into the inner cavity of the dropping unit. The feeding port enters the inner cavity through a feeding pipe fixedly connected with the top plate of the inner cavity. The feeding pipe can send the acetaldehyde solution from the second feeding port into the inner cavity, and can also fix the top plate and the outer wall.

[0018] The second and third limiters are arranged on the side wall inside the inner cavity respectively. The second limiter is located at the lower position and is used to sense the lowest liquid level in the inner cavity. When the lowest liquid level reaches the second limiter, it indicates that the amount of acetaldehyde solution in the inner cavity is small and needs to be supplemented. At this time, the external control system is used to control the acetaldehyde solution to be poured into the second feeding port. When the liquid level in the inner cavity reaches the third limiter, it indicates that the amount of acetaldehyde solution in the inner cavity is sufficient. At this time, the control system is used to control the acetaldehyde solution to stop being poured into the first feeding port.

[0019] Due to the hollow area arranged on the top plate, the third limiter is preferably arranged at a position 1 / 3 of the height of the inner cavity from the top plate, so as to avoid the solution in the inner cavity from splashing out of the hollow area of the top plate and into the second space under the action of stirring when the liquid level in the inner cavity is high.

[0020] In order to avoid the solution in the inner cavity from splashing into the second space, the top plate of the inner cavity can be arranged to be concave, that is, the periphery of the top plate is high and the center is low. Even if a small amount of solution splashes out of the hollow area, it will also slide down the hollow area to the inner cavity along the surface of the concave top plate due to the action of the gravity of the liquid.

[0021] The drop adding unit has an overall upright and slender structure, that is, the height of the inner cavity is greater than the inner diameter thereof. The main effect is to increase the internal pressure of the liquid under the condition of the same inner cavity volume, which is beneficial to the solution added by drop to enter the reaction liquid in the reaction unit below, and to reduce the reaction liquid from entering the cross beam in the reverse direction through the liquid outlet hole on the cross beam as much as possible. The drop adding unit is fixed by an external support frame to ensure its stability.

[0022] A liquid inlet is arranged at the bottom of the inner cavity of the drop adding unit, and a drop adding pipe is arranged below the liquid inlet. The drop adding pipe is arranged in the vertical rod and does not contact the inner wall of the vertical rod, and does not affect the rotation of the vertical rod. The uppermost end of the drop adding pipe communicates with the liquid inlet. The drop adding pipe passes through the second bevel gear and the top of the reaction unit inside the vertical pipe to reach the position of the cross beam at the highest point. The lower end of the drop adding pipe is open. A circular blocking piece is arranged between the outer side wall of the lower end of the drop adding pipe and the inner wall of the vertical rod. The blocking piece is fixedly connected with the outer wall of the lower end of the drop adding pipe. A sealing gasket is arranged on the circumferential edge of the blocking piece located on one side of the inner wall of the vertical rod. The inner wall of the vertical rod is provided with a slot at the position matched with the sealing gasket. The sealing gasket is embedded in the slot and tightly contacts with the inner wall of the slot, but is not fixed with the slot, so as to achieve the purpose of sealing the lower end of the third space. The sealing gasket does not affect the rotation of the vertical rod, and the rotation of the vertical rod does not affect the sealing effect of the sealing gasket.

[0023] The third space is formed between the drop adding pipe and the vertical pipe, and is used to contain cooling water. The blocking piece and the sealing gasket are used to prevent the cooling water contained in the third space from entering the lower end space of the vertical rod.

[0024] A control valve is arranged at one end of the drop adding pipe close to the drop adding unit, and is used to control the drop adding speed of the acetaldehyde solution.

[0025] When the control valve on the dropping tube is opened, the acetaldehyde solution in the dropping unit inner cavity enters the dropping tube through the inlet at the bottom of the inner cavity under the action of gravity, and drips into the lower end of the vertical rod, then enters the horizontal rod through the one-way valve on the horizontal rod, and finally enters the reaction liquid in the reaction unit through the liquid outlet hole on the horizontal rod. With the synchronous stirring of the horizontal rod, the entering acetaldehyde solution quickly mixes with the reaction liquid.

[0026] A hollow cylinder is arranged at the center of the top end of the reaction unit in the direction of the vertical rod, and the inner diameter of the hollow cylinder is just large enough to pass through the vertical rod. A first space is arranged at the top of the reaction unit, a water inlet pipe is arranged on one side wall of the first space, and a water outlet pipe is arranged on the other side wall. The water outlet pipe extends into the interior of the first space and communicates with the hollow cylinder in the middle region of the first space. The cooling water enters the first space through the water inlet pipe, but the cooling water in the first space cannot be directly discharged through the water outlet pipe. The space of the first space except the hollow cylinder in the middle region is a hollow structure. A plurality of first holes and a plurality of second holes are arranged on the inner wall of the hollow cylinder, wherein the first holes are used to discharge the cooling water in the first space into the hollow cylinder, and the cooling water entering the hollow cylinder is discharged to the outside of the first space through the second holes. All the second holes communicate with the water outlet pipe. At least one first hole and one second hole are arranged.

[0027] The region where the vertical rod intersects with the first space is the exchange zone of the cooling water. A plurality of through holes matching the first holes and the second holes are arranged on the inner wall of the vertical rod. When the through hole on the inner wall of the vertical rod matches and communicates with the first hole on the hollow cylinder during the rotation of the vertical rod, the cooling water in the interior of the first space enters the third space between the vertical rod and the dropping tube through the through hole on the vertical rod. When the through hole on the vertical rod matches and communicates with the second hole on the hollow cylinder, the cooling water in the third space enters the water outlet pipe and is discharged to the outside of the first space. The flow of the cooling water is realized, and the heat exchange effect is improved.

[0028] A plurality of through holes are arranged on the vertical rod, and the through holes frequently match and communicate with the first holes and the second holes during the rotation of the vertical rod, so that the cooling water frequently flows.

[0029] When the cooling water enters the third space in the vertical rod from the first space, the cooling water can completely wrap the dropping tube, from the bottom of the dropping tube and the inner cavity of the dropping unit to the lowest end of the highest horizontal rod. That is, the acetaldehyde solution in the dropping tube is always cooled by the cooling water during the dropping process, and the effect of maintaining the low temperature of the acetaldehyde solution is better.

[0030] When the acetaldehyde solution drops to the lower end of the vertical rod, it enters the horizontal rod through the one-way valve, and then enters the reaction liquid through the liquid outlet hole. Even if part of the acetaldehyde solution that has not entered the reaction liquid in time is heated and volatilized to rise to the upper drop adding pipe, since the drop adding pipe is immersed in the cooling water at all times, the volatilized acetaldehyde solution will be condensed in time and drop down again.

[0031] It should be noted that the horizontal rod is immersed in the reaction liquid, the liquid outlet hole is arranged on the horizontal rod and is open, since the drop added acetaldehyde solution is located at a high position, and the liquid level of the acetaldehyde solution is higher than the position of the liquid outlet hole on the horizontal rod, during the continuous drop adding process, since the pressure generated by the acetaldehyde solution is higher than the pressure of the reaction liquid at the position of the liquid outlet hole, the liquid flow direction at the liquid outlet hole is that the acetaldehyde solution in the horizontal rod flows to the reaction liquid. When drop adding is not performed, since the one-way valve between the horizontal rod and the vertical rod is closed, even if the reaction liquid enters the horizontal rod from the liquid outlet hole, the reaction liquid will not enter the vertical rod, and the situation that the solution flows back into the inside of the vertical rod will not occur.

[0032] The beneficial effects of the utility model are:

[0033] 1. The third space between the vertical rod and the drop adding pipe is filled with cooling water, the whole drop adding pipe is immersed in the cooling water, the continuous cooling of the acetaldehyde solution during the drop adding process is ensured, and the cooling effect is improved.

[0034] 2. The first space is arranged at the top of the reaction unit and is filled with cooling water, the acetaldehyde solution that is not reacted in time and volatilized to the inner surface of the top of the reaction unit is condensed in time and then dropped to the reaction liquid below again, the utilization rate of acetaldehyde is increased.

[0035] 3. The exchange area is arranged at the intersection of the vertical rod and the first space, the cooling water in the first space and the third space is sent to the water outlet pipe through the exchange area and then is discharged to the outside of the device, the flowability of the cooling water is ensured, and the cooling effect of the cooling water is improved.

[0036] 4. The liquid outlet holes are arranged on the horizontal rod, the acetaldehyde solution is dispersed in the inside of the reaction liquid in time during stirring, the contact area between the acetaldehyde solution and the reaction liquid is increased and fast reaction is realized, and the volatilization of acetaldehyde caused by local overheating due to the direct drop of the acetaldehyde solution into the reaction is avoided.

[0037] 5. The drop adding unit and the reaction unit are connected by the same vertical rod, only one set of driving unit is arranged, and the simultaneous stirring of the drop adding unit and the reaction unit is realized, and the cost of the equipment is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 Overall schematic view of the device;

[0039] Figure 2 Schematic view of the drop adding unit;

[0040] Figure 3 Horizontal drive and vertical drive schematic diagram;

[0041] Figure 4 Horizontal drive and vertical drive connection schematic diagram;

[0042] Figure 5 Dropping unit top view;

[0043] Figure 6 First space and vertical rod and dropping pipe relative position schematic diagram;

[0044] Figure 7 Exchange space schematic diagram;

[0045] Figure 8 First space and exchange area in and out cooling water schematic diagram;

[0046] Figure 9 First space and exchange area in incommunicative state schematic diagram;

[0047] Figure 10 First space and exchange area in communicative state schematic diagram;

[0048] Figure 11 Dropping pipe and vertical rod connection mode schematic diagram.

[0049] Reference signs:

[0050] 11 dropping unit; 12 reaction unit; 13 first stirring; 14 drive unit; 121 first feeding port; 122 discharge port; 123 discharge valve; 124 first limiter; 131 vertical rod; 132 horizontal rod; 1321 liquid outlet hole; 1322 one-way valve; 141 motor; 142 horizontal drive; 143 vertical drive; 15 supporting leg; 16 first space; 17 exchange area; 18 blocking piece; 21 outer wall; 22 inner cavity; 221 second limiter; 222 third limiter; 23 second space; 24 stirring rod; 241 stirring blade; 25 liquid inlet; 251 dropping pipe; 252 control valve; 26 second feeding port; 261 feeding pipe; 27 supporting column; 28 first rotating shaft; 29 second rotating shaft; 31 drive rod; 32 first bevel gear; 33 second bevel gear; 51 hollow area; 52 top plate; 61 through hole; 71 hollow cylinder; 72 first opening; 73 second opening; 74 water inlet pipe; 75 water outlet pipe; 101 third space; 102 slot; 103 sealing gasket. DETAILED DESCRIPTION

[0051] In order to fully understand the dropping device in the technical solution, the following embodiments are listed for specific and detailed description.

[0052] The device in this embodiment is mainly divided into three parts, namely the uppermost dropping unit 11, the middle driving unit 14 and the lower reaction unit 12. The driving unit 14 drives the stirring units of the whole device, and the stirring units are respectively located in the upper dropping unit 11 and the lower reaction unit 12. The stirring units of the two parts are connected through the middle common vertical rod 131 and are synchronously driven by the middle driving unit 14. The stirring effects of the dropping unit 11 and the reaction unit 12 are realized through one driving unit 14.

[0053] The reaction unit 12 described above is flat as a whole, that is, the length in the horizontal direction is greater than the height of the reaction unit 12. The main purpose is to reduce the liquid pressure in the reaction unit 12 while ensuring the volume of the whole reaction unit 12.

[0054] A first feeding port 121 is arranged on one side above the reaction unit 12, and the reaction raw materials are put into the reaction unit 12. A discharge port 122 is arranged at the lowermost part of the reaction unit 12, and a discharge valve 123 is arranged at the discharge port 122, which is used to discharge the materials in the reaction unit 12 after the reaction is completed. The bottom of the reaction unit 12 is arranged in an inclined shape, and the discharge port 122 is the lowest point, which is convenient for the gravity to completely discharge the materials in the reactor after the reaction is completed.

[0055] A first stirring unit 13 is arranged in the reaction unit 12, which includes a middle vertical rod 131 and horizontal rods 132 arranged on both sides of the vertical rod 131. The horizontal rods 132 are arranged above and below the vertical rod 131, and there are four horizontal rods 132 in total. One end of the horizontal rod 132 is connected with the vertical rod 131, and the other end is close to the inner wall of the reaction unit 12, which ensures the stirring effect of the liquid in the reaction unit 12. The horizontal rod 132 and the lower end of the vertical rod 131 are in communication, and a plurality of liquid outlets 1321 are arranged at the bottom of the horizontal rod 132. The inside of the vertical rod 131 between the horizontal rod 132 at the highest position and the horizontal rod 132 at the lowest position is hollow, and the lowest end of the vertical rod 131 is at the same horizontal plane as the bottom surface of the horizontal rod 132 at the lowest position, which is beneficial to the liquid in the hollow section of the lower end of the vertical rod 131 to flow out from the liquid outlets 1321 on the horizontal rod 132 at the lowest position. Unidirectional valves 1322 are arranged at the communication positions of the horizontal rod 132 and the vertical rod 131, which only allow the liquid to flow from one side of the vertical rod 131 to the horizontal rod 132, avoiding the liquid in the horizontal rod 132 to flow into the vertical rod 131.

[0056] A first limiter 124 is arranged on the inner side wall of the reaction unit 12 opposite to the first feeding port 121, and the limiter 124 is electrically connected with the central control system for controlling the liquid level in the reactor. When the liquid level reaches the first limiter 124 during the feeding of the reaction liquid into the reactor through the first feeding port 121, the feeding of the first feeding port 121 is stopped by the external control system. The position of the first limiter 124 is lower than the height of the first feeding port but higher than the height of the highest horizontal rod 132.

[0057] The one-way valves 1322 at the connection between the horizontal rods 132 and the vertical rods 131 are electrically connected with the central control system, and can be controlled by the external control system. That is, the liquid inside the lower end of the vertical rod 131 can be selected to flow out through the liquid outlet holes 1321 under which horizontal rods 132 by controlling the opening or closing of the one-way valves 1322. For example, when the reaction liquid is less and the liquid surface is lower than the highest horizontal rod 132, the two one-way valves 1322 on the highest horizontal rod 132 can be closed to prevent the liquid in the vertical rod 131 from flowing out from the highest horizontal rod 132, so as to avoid that the liquid dropped from the liquid outlet holes 1321 does not directly enter the reaction liquid inside, thereby reducing the mixing effect.

[0058] The top of the reaction unit 12 is provided with a first space 16, and cooling water is introduced into the first space 16 by the external control system. At this time, the top of the entire reaction unit 12 is in a cooling state. When part of the unreacted acetaldehyde solution in the reaction unit 12 volatilizes to the lower surface of the top of the reaction unit 12, the volatilized acetaldehyde is condensed due to the cooling effect of the top of the reaction unit 12 and then drops to the reaction liquid below for further reaction, thereby improving the utilization rate of acetaldehyde.

[0059] The vertical rods 131 in the first stirring unit 13 in the reaction unit 12 penetrate the top of the reaction unit 12 upward and continue to extend upward to the lower side of the dropping unit 11. A driving unit 14 is arranged between the dropping unit 11 and the reaction unit 12, and the driving unit 14 is composed of a horizontal driving unit 142 and a vertical driving unit 143. A supporting leg 15 is arranged on the upper surface of the top of the reaction unit 12 for supporting the middle driving unit 14. The driving unit 14 mainly includes a motor 141, a driving rod 31 and a bevel gear. The bevel gear includes a first bevel gear 32 and a second bevel gear 33. The second bevel gear 33 is arranged on the vertical rod 131 between the dropping unit 11 and the reaction unit 12, and the first bevel gear 32 is arranged on one end of the driving rod 31 close to the vertical rod 131 and is in meshing driving relationship with the second bevel gear 33. The other end of the driving rod 31 is connected with the motor 141. The rotation of the driving rod 31 is driven by the movement of the motor 141, and then the first bevel gear 32 is rotated. The rotation of the first bevel gear 32 and the second bevel gear 33 converts the horizontal rotation into the vertical rotation, and then drives the rotation of the vertical rod 131.

[0060] The drop adding unit 11 is composed of an outer wall 21 and an inner cavity 22, and a second space 23 is formed between the outer wall 21 and the inner cavity 22. An upright rod 131 extending upwardly passes through the outer wall 21 at the bottom of the drop adding unit 11 to reach the bottom of the inner cavity 22, and the bottom of the inner cavity 22 is connected with the top end of the upright rod 131 through a support column 27, which serves to support the entire inner cavity 22. The top end of the support column 27 and the upright rod 131 are connected through a first rotating shaft 28, and the upright rod 131 can rotate relative to the support column 27 through the first rotating shaft 28. A second rotating shaft 29 is arranged at the connection between the upright rod 131 and the outer wall 21 of the drop adding unit 11, and the upright rod 131 can rotate relative to the outer wall 21 through the second rotating shaft 29.

[0061] A symmetrical bent stirring rod 24 is arranged on the upright rod 131 between the first rotating shaft 28 and the second rotating shaft 29 and located in the second space 23. An annular hollow area 51 is arranged on the top plate 52 of the inner cavity 22, and a vertical stirring blade 241 is arranged at the front end of the bent stirring rod 24, which enters the inner cavity 22 of the drop adding unit 11 through the annular hollow area 51 on the top plate 52. When the upright rod 131 rotates, the upright rod 131 drives the stirring rod 24 to rotate, and then the stirring blade 241 rotates along the annular hollow area 51 on the top plate 52 of the inner cavity 22, so as to realize stirring of the solution in the inner cavity 22 of the drop adding unit 11 and avoid the stratification of the acetaldehyde solution due to long-term standing.

[0062] A second feeding port 26 is arranged directly above the outer wall 21 of the drop adding unit 11, which is used to pour the acetaldehyde solution into the inner cavity 22 of the drop adding unit 11. The second feeding port 26 passes through the top plate 52 of the inner cavity 22 into the inner cavity 22 through a feeding pipe 261, and the feeding pipe 261 is fixedly connected with the top plate 52 of the inner cavity 22. The feeding pipe 261 can realize the feeding of the acetaldehyde solution from the second feeding port 26 into the inner cavity 22, and can also realize the fixation of the top plate 52 and the outer wall 21.

[0063] A second limiter 221 and a third limiter 222 are arranged on the inner wall of the inner cavity 22, respectively, and both are electrically connected with the central control system. The second limiter 221 is located at the lower position and is used to sense the lowest liquid level in the inner cavity 22. When the lowest liquid level reaches the second limiter 221, it indicates that the amount of the acetaldehyde solution in the inner cavity 22 is small, and it needs to be supplemented. At this time, the external control system controls the pouring of the acetaldehyde solution from the second feeding port 26. When the liquid level in the inner cavity 22 reaches the third limiter 222, it indicates that the amount of the acetaldehyde solution in the inner cavity 22 is sufficient, and at this time the control system controls to stop the pouring of the reaction solution from the first feeding port 121.

[0064] Due to the hollow area 51 of the top plate 52, the third limiter 222 is arranged at a position 1 / 3 of the height of the inner cavity, so as to avoid the solution from splashing into the second space 23 when the liquid level in the inner cavity 22 is high and under the action of stirring.

[0065] The drop adding unit 11 is in an upright and slender structure, i.e., the height of the inner cavity 22 is greater than the inner diameter, which is mainly to increase the internal pressure of the liquid under the condition of the same volume of the inner cavity 22, so as to facilitate the solution added into the reaction liquid in the reaction unit 12 below, and to reduce the reaction liquid from entering the horizontal rod 132 in the opposite direction through the liquid outlet hole 1321 on the horizontal rod 132 as much as possible. The drop adding unit 11 is fixed by an external support frame (not shown in the figure) to ensure its stability.

[0066] The liquid inlet 25 is arranged at the bottom of the inner cavity 22 of the drop adding unit 11, and the drop adding pipe 251 is arranged below the liquid inlet 25. The drop adding pipe 251 is arranged in the vertical rod 131 and does not contact the inner wall of the vertical rod 131, and does not affect the rotation of the vertical rod 131. The uppermost end of the drop adding pipe 251 communicates with the liquid inlet 25, and the drop adding pipe 251 passes through the second bevel gear 33 and the top of the reaction unit 12 downward in the vertical pipe to reach the horizontal beam position at the highest position. The lower end of the drop adding pipe 251 is open, and the outer side of the lower end of the drop adding pipe 251 is provided with a circular blocking piece 18 on the inner wall of the vertical rod 131. The blocking piece 18 is fixedly connected with the outer wall 21 of the lower end of the drop adding pipe 251, and a sealing gasket 103 is arranged on the circumference of the blocking piece 18 on one side of the inner wall of the vertical rod 131. The inner wall of the vertical rod 131 is provided with a slot 102 at a position matched with the sealing gasket 103, and the sealing gasket 103 is embedded in the slot 102 and tightly contacts the inner wall of the slot 102 but is not fixed with the slot 102. The sealing gasket 103 does not affect the rotation of the vertical rod 131, and the rotation of the vertical rod 131 does not affect the sealing effect of the sealing gasket 103.

[0067] The third space 101 is formed between the drop adding pipe 251 and the vertical pipe for containing cooling water, and the blocking piece 18 and the sealing gasket 103 prevent the cooling water in the third space 101 from entering the lower end space of the vertical rod 131.

[0068] A control valve 252 is arranged at one end of the drop adding pipe 251 close to the drop adding unit 11, for controlling the drop adding speed of the acetaldehyde solution.

[0069] When the control valve 252 on the dropping tube 251 is opened, the acetaldehyde solution in the inner cavity 22 of the dropping unit 11 enters the dropping tube 251 through the bottom liquid inlet 25 of the inner cavity 22 under the action of gravity, and drips into the lower end of the vertical rod 131, then enters the horizontal rod 132 through the one-way valve 1322 on the horizontal rod 132, and finally enters the reaction liquid in the reaction unit 12 through the liquid outlet hole 1321 on the horizontal rod 132. With the synchronous stirring of the horizontal rod 132, the entering acetaldehyde solution rapidly mixes with the reaction liquid.

[0070] A hollow cylinder 71 is formed at the top center of the reaction unit 12 in the direction of the vertical rod 131, and the inner diameter of the hollow cylinder 71 is just large enough to pass through the vertical rod 131. The first space 16 is provided at the top of the reaction unit 12, a water inlet pipe 74 is provided on one side wall of the first space 16, and a water outlet pipe 75 is provided on the other side wall. The water outlet pipe 75 extends into the interior of the first space 16 and communicates with the hollow cylinder 71 in the middle region of the first space 16. Cooling water enters the first space 16 from the water inlet pipe 74, but the cooling water in the first space 16 cannot be directly discharged through the water outlet pipe 75. The space of the first space 16 except the hollow cylinder 71 in the middle region is hollow. A first opening 72 and a second opening 73 are provided on the inner wall of the hollow cylinder 71, and the second opening 73 communicates with the water outlet pipe 75. The first opening 72 is used to discharge the cooling water in the first space 16 into the hollow cylinder 71, and the cooling water entering the hollow cylinder 71 is discharged to the outside of the first space 16 through the second opening 73 and the water outlet pipe 75.

[0071] The region where the vertical rod 131 intersects with the first space 16 is the cooling water exchange zone 17. Four through holes 61 are formed on the inner wall of the vertical rod 131, which match the first opening 72 and the second opening 73. When the through hole 61 on the inner wall of the vertical rod 131 matches and communicates with the first opening 72 on the hollow cylinder 71 during the rotation of the vertical rod 131, the cooling water in the first space 16 enters the third space 101 between the vertical rod 131 and the dropping tube 251 through the through hole 61 on the vertical rod. When the through hole 61 on the vertical rod 131 matches and communicates with the second opening 73 on the hollow cylinder 71, the cooling water in the third space 101 enters the water outlet pipe 75 and is discharged to the outside of the first space 16. This realizes the flow of cooling water and improves the heat exchange effect.

[0072] During the rotation of the vertical rod 131, the through hole 61 frequently matches and communicates with the first opening 72 and the second opening 73, realizing the frequent flow of cooling water.

[0073] When the cooling water enters the third space 101 in the vertical rod 131 from the first space 16, the cooling water can completely wrap the dropping tube 251, up to the bottom of the dropping tube 251 and the cavity 22 in the dropping unit 11, and down to the lowest end of the dropping tube 251 close to the highest horizontal rod 132. That is, the process of dropping acetaldehyde solution in the dropping tube 251 is always cooled by the cooling water, and the effect of maintaining the low temperature of the acetaldehyde solution is better.

[0074] When the acetaldehyde solution drops to the lower end of the vertical rod 131, it enters the horizontal rod 132 through the one-way valve 1322, and then enters the reaction liquid through the liquid outlet hole 1321. Even if part of the acetaldehyde solution that does not enter the reaction liquid in time is heated and volatilized to rise to the upper dropping tube 251, since the dropping tube 251 is immersed in the cooling water at all times, the volatilized acetaldehyde solution will condense and drop down again in time.

[0075] It should be noted that in the present application, terms such as "upper", "lower", "front", "side", "bottom", "top" are described according to the positional relationship in the drawings of the present application, and are not intended to limit the scope of the present application. The change or adjustment of the relative relationship is also considered as the scope of the present application without substantial change of the technical content.

[0076] The above description is a detailed description of the preferred and feasible embodiments of the present application, but the embodiments are not intended to limit the scope of the patent application of the present application. Any equivalent changes or modifications made under the technical spirit of the present application should be considered within the scope of the patent of the present application.

Claims

1. A dropping device in the production of metronidazole, characterized by, The device comprises a dropping unit (11), a driving unit (14), a reaction unit (12) and a stirring unit, the driving unit (14) is located between the dropping unit (11) and the reaction unit (12), the dropping unit (11) is located directly above the reaction unit (12), and the two are connected through a vertical rod (131); the stirring units are located in the dropping unit (11) and the reaction unit (12) respectively and are driven by the same driving unit (14); the top of the reaction unit (12) is provided with a first space (16); the lower part of the dropping unit (11) is provided with a dropping pipe (251), the dropping pipe (251) is arranged in the interior of the vertical rod (131) and forms a third space (101) with the vertical rod (131); the first space (16) and the third space (101) can be filled with cooling liquid.

2. The dropping device for the production of metronidazole according to claim 1, characterized in that, The stirring unit in the reaction unit (12) is composed of a vertical rod (131) and a horizontal rod (132) arranged horizontally on the side of the vertical rod (131), the vertical rod (131) and the horizontal rod (132) are both hollow structures, and a one-way valve (1322) is arranged at the communication part of the two, and a liquid outlet hole (1321) is arranged below the horizontal rod (132); a supporting leg (15) is arranged vertically at the top of the reaction unit (12), and a driving unit (14) is arranged on the supporting leg (15), the driving unit (14) comprises a motor (141), a horizontal drive (142) and a vertical drive (143), and the motor (141) drives the vertical rod (131) to rotate along the vertical direction through the transmission between the horizontal drive (142) and the vertical drive (143).

3. The dropping device for the production of metronidazole according to claim 1, characterized in that, The stirring unit in the dropping unit (11) is composed of a stirring rod (24) and a stirring blade (241), the dropping unit (11) comprises an outer wall (21) and an inner cavity (22), and a second space (23) is formed between the two, and the stirring rod (24) is located in the second space (23).

4. The dropping device for the production of metronidazole according to claim 3, characterized in that An annular hollow area (51) is arranged on the top plate (52) at the top of the inner cavity (22), and the stirring blade (241) can rotate along the hollow area (51) to realize stirring in the dropping unit (11).

5. The dropping device for the production of metronidazole according to claim 4, characterized in that A liquid inlet (25) is arranged at the bottom of the inner cavity (22), the liquid inlet (25) is communicated with the dropping pipe (251) below, the top plate (52) of the inner cavity (22) is connected and fixed with the outer wall (21) through a feeding pipe (261) in the middle, the bottom of the inner cavity (22) of the dropping unit (11) is connected with the top end of the vertical rod (131) through a first rotating shaft (28), and the bottom of the outer wall (21) is connected with the vertical rod (131) through a second rotating shaft (29).

6. The dropping device for the production of metronidazole according to claim 5, characterized in that The outer wall of the lower end of the dropping pipe (251) is provided with a circular blocking piece (18) between the inner wall of the vertical rod (131), the blocking piece (18) is fixedly connected with the outer wall of the lower end of the dropping pipe (251), the inner wall of the vertical rod (131) is provided with a sealing gasket on one side of the circumferential edge of the blocking piece (18), the position of the inner wall of the vertical rod (131) matched with the sealing gasket is provided with a slot (102), and the sealing gasket is embedded in the slot (102), so as to realize sealing of the lower end of the third space (101).

7. The dropping device for the production of metronidazole according to claim 6, characterized in that The top end of the reaction unit (12) is provided with a hollow cylinder (71) in the direction of the vertical rod (131) and at the central position of the first space (16), and the inner diameter of the hollow cylinder (71) is consistent with the outer diameter of the vertical rod (131), and the area of the first space (16) except the hollow cylinder (71) is a hollow structure.

8. The dropping device for the production of metronidazole according to claim 7, characterized in that One side of the first space (16) is provided with a water inlet pipe (74), and the other side wall is provided with a water outlet pipe (75), the water outlet pipe (75) extends into the inside of the first space (16) and communicates with the hollow cylinder (71) in the middle area of the first space (16).

9. The dropping device for the production of metronidazole according to claim 8, characterized in that The inner wall of the hollow cylinder (71) is symmetrically provided with a first opening (72) and a second opening (73), the first opening (72) communicates with the water inlet pipe (74), and the second opening (73) communicates with the water outlet pipe (75).

10. The dropping device for the production of metronidazole according to claim 9, characterized in that The inner wall of the hollow cylinder (71) is completely matched with the vertical rod (131), and the inner wall of the vertical rod (131) is provided with a through hole (61) matched with the first opening (72) and the second opening (73).

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