Rectification condensing device for trichloropyridine production

Abstract

The utility model relates to a rectification condensing device for trichloropyridine production belongs to trichloropyridine production and processing equipment technical field, the rectification condensing device for trichloropyridine production includes: condenser pipe, the condenser pipe inside forms condensing cavity, condenser pipe lower extreme one side is equipped with the air inlet pipe, is located the air inlet pipe of condenser pipe lower extreme and is set up and is connected the exhaust port position of rectification tower, and the air inlet assembly is installed to condenser pipe inside in the position department of setting air inlet pipe, the rectification condensing device for trichloropyridine production can realize the inside storage of bending U -shaped pipe after stopping the ventilation of air inlet pipe, avoids the liquid drop in the condenser pipe to return to the rectification tower inside through the air inlet pipe, like this will not cause the reflux pollution to the rectification tower inside.

Description

Technical Field

[0001] This utility model relates to a distillation and condensation device for the production of trichloropyridine, belonging to the technical field of trichloropyridine production and processing equipment. Background Technology

[0002] Trichloropyridine is an important class of chlorine-containing nitrogen heterocyclic compounds with the molecular formula C5H2Cl3N. Due to the different substitution positions of the chlorine atom on the pyridine ring, there are many isomers (the most common being 2,3,5-trichloropyridine, 2,3,6-trichloropyridine, 2,4,5-trichloropyridine, 2,4,6-trichloropyridine, etc.).

[0003] In the production of trichloropyridine (especially the common 2,3,5-trichloropyridine and 2,3,6-trichloropyridine), distillation is a crucial purification step used to separate the target trichloropyridine isomers, unreacted feedstocks, byproducts, and other chloropyridine impurities. Condensation is an indispensable part of the top operation of the distillation column, through which the high-temperature, high-purity trichloropyridine vapor (or a mixture with other light components) distilled from the top of the distillation column can be cooled and condensed into a liquid for recovery.

[0004] In related technologies, the condensation of high-temperature, high-purity trichloropyridine vapor distilled from the top of a distillation column is generally carried out by a condenser. The condenser includes condenser tubes, and multiple heat exchange tubes are arranged and installed in the middle of the condenser tubes. The heat exchange tubes are filled with a heat exchange medium, such as cooling water or low-temperature cooling oil. A drain pipe is provided on one side of the lower end of the condenser tube, and an inlet pipe is installed on the other side of the lower end of the condenser tube. At the same time, an outlet pipe is provided on one side of the upper end of the condenser tube. The outlet pipe and the inlet pipe are installed in a staggered manner at the upper and lower ends of the condenser tube.

[0005] The condenser has a simple structure and is easy to use. Trichloropyridine vapor distilled from the top of the distillation column enters the condenser tube through the inlet pipe, and then the heat exchange medium is transported inside the heat exchange tube. During the process of the vapor rising inside the condenser tube, it can come into contact with the heat exchange tube to exchange heat and release a large amount of heat before turning into droplets and depositing inside the condenser tube. Finally, it is discharged through the drain pipe. By installing the outlet pipe and the inlet pipe at the upper and lower ends of the condenser tube in a staggered manner, the residence time of the vapor inside the heat exchange tube can be extended, thereby improving the condensation efficiency.

[0006] However, this type of condenser also has some drawbacks. For example, some of the droplets after heat exchange and condensation will flow back into the distillation column through the inlet pipe. These backflowing droplets not only contaminate the inside of the distillation column, but also require secondary heating and evaporation of these liquids, thus increasing the energy consumption of the entire distillation column. At the same time, the trichloropyridine droplets condensed inside the condenser tube may be in a saturated state (gas-liquid equilibrium temperature). Slight temperature or pressure fluctuations may cause flash evaporation. If the liquid that is not completely subcooled enters the receiving tank and flashes, the resulting vapor will disrupt the vacuum of the entire trichloropyridine production system, ultimately affecting the operational stability of the distillation column. Utility Model Content

[0007] To solve the above-mentioned technical problems, this utility model provides a distillation and condensation device for the production of trichloropyridine, which solves the problems in the background art where the condensate is recirculated back to the distillation column, causing pollution, and the incompletely subcooled liquid flashes after entering the receiving tank, and the generated steam will destroy the system vacuum and affect the stable operation of the distillation column.

[0008] The technical solution adopted by this utility model to solve its technical problem is:

[0009] A distillation and condensation apparatus for the production of trichloropyridine, the apparatus comprising:

[0010] A condenser tube, the interior of which forms a condensation chamber; an inlet pipe is provided on one side of the lower end of the condenser tube, located at the position where the inlet pipe at the lower end of the condenser tube connects to the exhaust port of the distillation column, and an inlet assembly is installed inside the condenser tube at the position where the inlet pipe is provided;

[0011] The intake assembly includes a bent U-shaped tube and a guide plate. The bent U-shaped tube is formed by connecting two U-shaped tubes with opposite opening directions. One end of the bent U-shaped tube is connected to one end of the intake pipe, and a guide plate is installed above the other end of the bent U-shaped tube. The lower end of the guide plate is welded and fixed to the outer wall of the bent U-shaped tube through a connecting frame. An exhaust gap is formed between the inner side of the guide plate and the outlet position of the bent U-shaped tube. The exhaust gap is designed with an opening that slopes downward.

[0012] Preferably, the condenser tube has two caps at its front and rear ends, and the heat exchange medium inlet pipe and heat exchange medium outlet pipe are respectively connected at the axial positions of the two caps at its front and rear ends; the condenser tube has two positioning plates at its front and rear ends, and multiple heat exchange tube holes are opened on the surface of the two positioning plates, and multiple heat exchange tubes are installed between the heat exchange tube holes opened on the surface of the two positioning plates; at the same time, an exhaust pipe is also provided on one side of the upper end of the condenser tube.

[0013] Preferably, the positioning plate is designed to be eccentrically upward, which is equivalent to the cover, and the heat exchange tube holes on the surface of the positioning plate form a raised design with the axis of the cover.

[0014] Preferably, the bottom of the condenser tube forms a condenser inner wall groove, and a subcooling tube is installed at the location of the condenser inner wall groove. One end of the subcooling tube is open directly facing the bottom of the condenser tube, and the other end of the subcooling tube is open to connect to the liquid outlet, which is installed on one side of the lower end of the condenser tube.

[0015] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0016] The distillation and condensation unit for trichloropyridine production described above has the following advantages compared with current condensers:

[0017] The system employs an intake assembly installed at the location of the intake pipe inside the condenser tube. This assembly includes a bent U-shaped tube and a guide plate. The bent U-shaped tube is formed by connecting two U-shaped tubes with opposite opening directions. One end of the bent U-shaped tube connects to one end of the intake pipe, and a guide plate is installed above the other end. During the rise of the exhaust gas, heat is released, causing condensation and the gas to fall as droplets. These droplets fall onto the surface of the guide plate and slide down into the condenser tube for temporary storage. This prevents some droplets from falling directly to the outlet of the bent U-shaped tube and flowing back into the tube. Simultaneously, the U-shaped design of the bent U-shaped tube creates a pressure differential. After the gas flow stops inside the intake pipe, the inside of the bent U-shaped tube is sealed, preventing droplets from flowing back into the distillation column through the intake pipe and thus avoiding backflow contamination of the distillation column.

[0018] In addition, by eccentrically raising the heat exchange tubes, the liquid storage space at the bottom of the condenser tubes is increased. This allows more coolant to accumulate and remain inside the condenser tubes for secondary heat exchange, while also improving the condensation efficiency of the retained droplets and the exhaust gas transported later. Furthermore, a condenser inner wall groove is formed at the bottom of the condenser tubes, and a subcooling tube is installed at the location of the condenser inner wall groove. By adding the subcooling tube, the trichloropyridine droplets can be further cooled, making the liquid temperature significantly lower than its boiling point (saturation temperature), eliminating the risk of flash evaporation. Moreover, due to the increased temporary storage volume of the trichloropyridine droplets, the outside of the subcooling tube can be almost completely covered, thus maintaining all-round heat dissipation and achieving a continuous and stable subcooling effect. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0020] Figure 1This is a schematic diagram of a distillation and condensation apparatus for the production of trichloropyridine according to this utility model.

[0021] Figure 2 This is a side view of a distillation and condensation apparatus for the production of trichloropyridine according to this utility model.

[0022] Figure 3 This is a schematic diagram of the installation of the subcooling tube in a distillation and condensation device for the production of trichloropyridine according to this utility model.

[0023] Figure 4 This is a schematic diagram of the air inlet assembly of a distillation and condensation device for the production of trichloropyridine according to this utility model.

[0024] In the diagram: 1-Heat exchange medium inlet pipe, 2-Sealing cap, 3-Positioning plate, 4-Heat exchange tube hole, 5-Outlet pipe, 6-Condenser tube, 7-Heat exchange tube, 8-Liquid outlet, 9-Subcooling tube, 10-Heat exchange medium discharge pipe, 11-Inlet pipe, 12-Positioning shaft seal, 13-Condenser inner wall groove, 14-Bent U-shaped tube, 15-Positioning frame, 16-Guide plate, 17-Connecting frame. Detailed Implementation

[0025] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0026] Please see Figure 1-4 This utility model provides a technical solution:

[0027] A distillation and condensation apparatus for the production of trichloropyridine, the apparatus comprising:

[0028] The condenser tube 6 has a condensation chamber inside it. The condensation chamber inside the condenser tube 6 is used to condense the high-temperature tail gas discharged from the top of the distillation column during the production of trichloropyridine to form trichloropyridine droplets.

[0029] For harsh environments such as trichloropyridine tail gas (high temperature, chlorine-containing, and possibly containing impurities), condenser tube 6 is made of 316 / 316L stainless steel. Since 316 / 316L stainless steel contains 23% molybdenum (Mo), it can significantly improve the resistance to chloride ion corrosion and pitting corrosion.

[0030] An inlet pipe 11 is provided on one side of the lower end of the condenser tube 6. The inlet pipe 11 is located at the exhaust port of the distillation column. An inlet assembly is installed inside the condenser tube 6 at the location where the inlet pipe 11 is provided. The inlet assembly can effectively prevent the liquid condensed and deposited inside the condenser tube 6 from flowing back into the distillation column through the inlet pipe 11 when trichloropyridine tail gas is transported through the inlet pipe 11. This would not only cause pollution inside the distillation column, but also require secondary heating and evaporation of these liquids, thus increasing the operating energy consumption of the entire distillation column.

[0031] Specifically, the intake assembly includes a bent U-shaped tube 14 and a guide plate 16. The bent U-shaped tube 14 is formed by connecting two U-shaped tubes with opposite opening directions. One end of the bent U-shaped tube 14 is connected to one end of the intake pipe 11, and the guide plate 16 is installed above the other end of the bent U-shaped tube 14. The lower end of the guide plate 16 is welded and fixed to the outer wall of the bent U-shaped tube 14 through a connecting bracket 17. An exhaust gap is formed between the inner side of the guide plate 16 and the outlet position of the bent U-shaped tube 14. The exhaust gap is designed with an opening angled downward. At the same time, the bent U-shaped tube 14 is connected and fixed to the inner wall of the condenser pipe 6 at the bending position through a positioning bracket 15.

[0032] In an embodiment of this utility model, when the high-temperature trichloropyridine tail gas discharged from the distillation column is conveyed into the condenser tube 6 through the provided air intake component, the high-temperature trichloropyridine tail gas enters the inside of the bent U-shaped tube 14 installed inside the condenser tube 6 after passing through the air intake pipe 11, and flows inside the bent U-shaped tube 14, and finally flows out from the formed exhaust gap position into the condenser tube 6 and is lifted inside the condenser tube 6.

[0033] During the process of the exhaust gas rising, heat is released and condensation occurs, turning into droplets that fall down. The droplets fall onto the surface of the guide plate 16 and slide down along the surface of the guide plate 16 into the condenser tube 6 for temporary storage. This can prevent some droplets from falling directly into the outlet of the bent U-shaped tube 14 and flowing back into the bent U-shaped tube 14.

[0034] As the number of droplets inside the condenser tube 6 increases and exceeds the height of the bent U-shaped tube 14 inside the condenser tube 6, some droplets will enter the bent U-shaped tube 14. The U-shaped design of the bent U-shaped tube 14 can create a pressure difference. After the gas flow inside the inlet pipe 11 is stopped, the inside of the bent U-shaped tube 14 can be sealed, preventing the droplets inside the condenser tube 6 from flowing back into the distillation column through the inlet pipe 11. This will prevent backflow contamination inside the distillation column.

[0035] Please see Figure 1In one embodiment of this utility model, two caps 2 are respectively provided at the front and rear ends of the outer side of the condenser tube 6. The heat exchange medium inlet pipe 1 and the heat exchange medium outlet pipe 10 are respectively connected at the axial positions of the two caps 2 provided at the front and rear ends of the outer side of the condenser tube 6. Two positioning plates 3 are respectively provided at the front and rear ends of the inner side of the condenser tube 6. Multiple heat exchange tube holes 4 are opened on the surface of the two positioning plates 3. Multiple heat exchange tubes 7 are installed between the heat exchange tube holes 4 opened on the surface of the two positioning plates 3. At the same time, an exhaust pipe 5 is also provided on one side of the upper end of the condenser tube 6.

[0036] In an embodiment of this utility model, when the high-temperature trichloropyridine tail gas discharged from the top of the distillation column is guided into the condenser 6 through the inlet pipe 11 and the inlet assembly, the heat exchange medium is then transported into the condenser 6 through the heat exchange medium feed pipe 1. The heat exchange medium can be cooling water or low-temperature cooling oil. After the heat exchange medium enters the condenser 6, it circulates simultaneously inside the multiple heat exchange pipes 7 installed inside the condenser 6.

[0037] As the trichloropyridine tail gas rises inside the condenser tube 6, it comes into contact with the outside of the heat exchange tube 7 and exchanges heat with the heat exchange tube 7. After releasing a large amount of heat, it condenses into droplets and deposits inside the condenser tube 6. At the same time, the heat exchange medium flowing inside the heat exchange tube 7 is heated by heat exchange and becomes hot water or hot oil. It is discharged from the heat exchange medium discharge pipe 10 and re-enters the refrigeration system for refrigeration and secondary utilization.

[0038] Meanwhile, since the exhaust pipe 5 and the intake pipe 11 are installed in a staggered manner above and below the condenser pipe 6, the residence time of the high-temperature trichloropyridine tail gas inside the condenser pipe 6 can be greatly extended, thereby improving the condensation efficiency of trichloropyridine.

[0039] Please see Figure 1 and Figure 2 In one embodiment of this utility model, the positioning plate 3 and the cover 2 do not share a common axis. The positioning plate 3 is designed to be eccentrically upward, which raises the heat exchange tube hole 4 on the surface of the positioning plate 3. This raises the height of the heat exchange tube 7 installed between the heat exchange tube holes 4 inside the condenser tube 6, thus expanding the liquid storage space at the bottom of the condenser tube 6. Therefore, more coolant can be collected and more coolant can be retained inside the condenser tube 6 for secondary heat exchange. This can simultaneously improve the condensation efficiency of the retained droplets and the exhaust gas transported later.

[0040] Please see Figure 1 and Figure 3In one embodiment of the present invention, a condenser inner wall groove 13 is formed at the bottom of the condenser tube 6. A subcooling tube 9 is installed at the position of the condenser inner wall groove 13. The subcooling tube 9 is installed and fixed at the position of the condenser inner wall groove 13 by a positioning shaft seal 12. One end of the subcooling tube 9 is open to the bottom of the condenser tube 6, and the other end of the subcooling tube 9 is open to the liquid outlet 8. The liquid outlet 8 is installed on one side of the lower end of the condenser tube 6.

[0041] In the embodiments of this utility model, the trichloropyridine droplets condensed inside the condenser tube 6 may be in a saturated state (gas-liquid equilibrium temperature). Slight temperature or pressure fluctuations may cause flash evaporation. If the liquid that is not completely subcooled enters the receiving tank and flashes, the generated vapor will disrupt the system vacuum and affect the stability of the distillation column operation.

[0042] By adding a subcooling tube 9, the trichloropyridine droplets can be further cooled, making the liquid temperature significantly lower than its boiling point (saturation temperature), thus eliminating the risk of flash evaporation.

[0043] In addition, increasing the liquid storage space at the bottom of the condenser tube 6 can improve the subcooling effect of trichloropyridine droplets at the location where they pass through the subcooling tube 9; (due to the increased temporary storage volume, the trichloropyridine droplets can basically completely cover the outside of the subcooling tube 9, thus maintaining all-round heat dissipation and achieving a continuous and stable subcooling effect).

[0044] The workflow of this embodiment is as follows:

[0045] The high-temperature trichloropyridine tail gas discharged from the top of the distillation column is guided into the condenser tube 6 through the inlet pipe 11 and the inlet assembly. Then, the heat exchange medium is transported into the condenser tube 6 through the heat exchange medium feed pipe 1. The heat exchange medium flows simultaneously in multiple heat exchange tubes 7.

[0046] As the trichloropyridine tail gas rises inside the condenser tube 6, it comes into contact with the outside of the heat exchange tube 7 and exchanges heat with the heat exchange tube 7. After releasing a large amount of heat, it condenses into droplets and deposits inside the condenser tube 6. Finally, it is discharged after being subcooled by the subcooling tube 9.

[0047] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

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