CN219251689U - Rectification system of 2, 4-difluoro nitrobenzene - Google Patents
Rectification system of 2, 4-difluoro nitrobenzene Download PDFInfo
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- CN219251689U CN219251689U CN202223570984.6U CN202223570984U CN219251689U CN 219251689 U CN219251689 U CN 219251689U CN 202223570984 U CN202223570984 U CN 202223570984U CN 219251689 U CN219251689 U CN 219251689U
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Abstract
The application provides a rectification system of 2, 4-difluoro nitrobenzene, including: the rectifying tower, with the condenser, reflux drum and the product jar that the steam export of rectifying tower communicates in proper order, the reflux drum still passes through the backwash pump intercommunication with the backward flow mouth of rectifying tower, the product jar still communicates with the negative pressure unit, the feed inlet of rectifying tower passes through the mother liquor pump intercommunication with the mother liquor storage tank. The bottom discharge port of the rectifying tower is communicated with the reboiler through a tower kettle pump, the vapor outlet of the reboiler is communicated with the vapor inlet of the rectifying tower, and the liquid outlet of the reboiler and the bottom discharge port of the rectifying tower are both communicated with a tower kettle liquid storage tank. The condenser is internally provided with a plurality of heat exchange tubes which are distributed in parallel, a first screw rod and a second screw rod are symmetrically arranged between two adjacent heat exchange tubes in a left-right direction relative to the center of the heat exchange tubes, and the screw thread directions of the first screw rod and the second screw rod are opposite. The rectification efficiency of the 2, 4-difluoronitrobenzene is improved, and the energy consumption is reduced.
Description
Technical Field
The application relates to the technical field of reduced pressure distillation devices, in particular to a rectification system of 2, 4-difluoro nitrobenzene.
Background
2, 4-difluoronitrobenzene is a chemical with the molecular formula of C 6 H 3 F 2 NO 2 Pharmaceutical intermediates. Is a drug flurbiprofen intermediate, and is also used as an intermediate of pesticides and liquid crystal materials. The storage of 2, 4-difluoronitrobenzene should keep the container sealed from the fire and heat source.
In the production of 2, 4-difluoronitrobenzene, fluoride is generally added into 2, 4-dichloronitrobenzene, dimethyl sulfoxide or N, N-methylformamide is used as a solvent, a phase transfer catalyst is added, the reaction is carried out under the protection of nitrogen, and the 2, 4-difluoronitrobenzene finished product with higher purity is obtained through filtration, water washing and reduced pressure distillation. However, when reduced pressure distillation is performed, the condenser used in the current reduced pressure distillation system is usually a tube type condenser, that is, a plurality of heat exchange tubes are arranged in the condenser, one of condensate and 2, 4-difluoronitrobenzene vapor discharged from the top of the distillation tower flows in the heat exchange tube, and the other flows outside the heat exchange tube, and the condensate and the 2, 4-difluoronitrobenzene vapor flow only through the heat exchange tubes, and because the volume of the condenser is large, the condensate flow is poor at the edge or corner of the condenser, a heat exchange dead zone occurs, the effective area for condensing steam is reduced, the condensing effect is poor, the 2, 4-difluoronitrobenzene vapor cannot be completely condensed into liquid, so that the 2, 4-difluoronitrobenzene vapor is required to be condensed by obtaining condensate with lower temperature and more quantity, but the problems of increased refrigeration capacity consumption and increased production cost are caused.
Disclosure of Invention
The present application provides a rectification system for 2, 4-difluoronitrobenzene to solve the above-mentioned problems in the background art.
The application provides a rectification system of 2, 4-difluoro nitrobenzene, including: the rectifying tower, with the condenser, reflux drum and the product jar that the steam export of rectifying tower communicates in proper order, the reflux drum still passes through the backwash pump intercommunication with the backward flow mouth of rectifying tower, the product jar still communicates with the negative pressure unit, the feed inlet of rectifying tower passes through the mother liquor pump intercommunication with the mother liquor storage tank.
The bottom discharge port of the rectifying tower is communicated with the reboiler through a tower kettle pump, the vapor outlet of the reboiler is communicated with the vapor inlet of the rectifying tower, and the liquid outlet of the reboiler and the bottom discharge port of the rectifying tower are both communicated with a tower kettle liquid storage tank.
The condenser is internally provided with a plurality of heat exchange tubes which are distributed in parallel, a first screw rod and a second screw rod are symmetrically arranged between two adjacent heat exchange tubes in a left-right direction relative to the center of the heat exchange tubes, and the screw thread directions of the first screw rod and the second screw rod are opposite.
Optionally, the end parts of the first screw rod and the second screw rod, which are close to the end heads at the two ends of the condenser, are fixedly connected with the plate pipe, and the end parts of the first screw rod and the second screw rod, which are close to the center position of the condenser, are fixedly connected with the inner wall of the condenser through connecting rods.
Optionally, a baffle plate is fixedly arranged on the outer wall of the heat exchange tube, and the direction of the section where the baffle plate is positioned is perpendicular to the axial direction of the heat exchange tube.
Alternatively, the baffles are straight or corrugated plates.
Optionally, the rectification system is further connected with a sub-cooler, and the sub-cooler is communicated with the condenser in series.
The condensate inlet of the condenser is communicated with the outlet of the mother liquor storage tank, and the condensate outlet of the condenser is communicated with the feed inlet of the rectifying tower through a mother liquor pump.
Optionally, a pressure sensor and a temperature sensor are arranged in the top of the rectifying tower.
Optionally, the negative pressure unit is provided with a first valve, the heat medium inlet of the reboiler is provided with a second valve, and the inlet of the tower kettle liquid storage tank connected with the bottom discharge port of the rectifying tower is provided with a third valve.
Optionally, the rectification system is provided with a controller, and the controller is respectively connected with the first valve, the second valve, the third valve, the reflux pump, the mother liquor pump, the tower kettle pump pressure sensor and the temperature sensor.
The rectification system of 2, 4-difluoro nitrobenzene provided by the application realizes rectification of 2, 4-difluoro nitrobenzene, and compared with the prior art, has the following beneficial effects:
(1) By arranging the vacuum rectification system, the boiling point of the 2, 4-difluoronitrobenzene is reduced, the addition of a heat medium is reduced, the energy consumption of the system is reduced, and the 2, 4-difluoronitrobenzene is conveniently gasified into 2, 4-difluoronitrobenzene vapor after heat exchange with the heating medium. And part of liquid phase 2, 4-difluoronitrobenzene in the reflux tank is conveyed to the rectifying tower through a reflux port of the rectifying tower to be rectified again, and the 2, 4-difluoronitrobenzene product with higher purity is obtained through repeated reflux and rectification.
(2) Through setting up first hob and second hob between two adjacent heat exchange tubes, can make the condensate take place the change of direction when flowing, and then make the condensate arouse the torrent when flowing, increase heat transfer area, and then improve the condensation efficiency of gaseous phase 2, 4-difluoro nitrobenzene. And the screw thread direction of first hob and second hob is opposite for condensate turbulence direction changes, and turbulence is stronger and stronger, avoids appearing the heat transfer dead zone in the condenser, and the heat transfer effect is also better, has improved the condensation efficiency of gaseous phase 2, 4-difluoro nitrobenzene, need not to reach the effect of condensation through the flow of increase condensate or the temperature that reduce the condensate. Thus, the use of cold is reduced, resources are saved, and the production cost is reduced.
(3) Through fixedly being provided with straight board or corrugated plate baffling piece at the outer wall of heat exchange tube, and the direction of baffling piece face place cross-section is perpendicular with the axial direction of heat exchange tube, can the at utmost change condensate direction to with first hob and second hob synergism, increase condensate turbulence degree, improve heat transfer area, avoid appearing the heat transfer dead zone in the condenser, and then improved the condensation efficiency of gaseous phase 2, 4-difluoro nitrobenzene.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief description will be given below of the drawings that are needed in the embodiments or the prior art descriptions, and it is obvious that the drawings in the following description are some embodiments of the present application, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a rectification system for 2, 4-difluoronitrobenzene according to an embodiment of the present application;
FIG. 2 is a schematic structural view of a condenser according to an embodiment of the present disclosure;
FIG. 3 is a schematic diagram of a rectification system for 2, 4-difluoronitrobenzene according to another embodiment of the present application;
fig. 4 is a schematic connection diagram of a controller according to an embodiment of the present application.
Reference numerals illustrate:
1: a rectifying tower; 2: a condenser; 3: a recooler; 4: a reflux drum; 5: a product tank; 6: a negative pressure unit; 7: a reboiler; 8: a tower bottom liquid storage tank; 9: a controller; 110; a reflux pump; 120: a mother liquid pump; 130: a tower bottom pump; 140: a pressure sensor; 150: a temperature sensor; 210: a heat exchange tube; 220: a first screw rod; 230: a second screw rod; 240: a plate tube; 250: a connecting rod; 260: a baffle plate; 610: a first valve; 710: a second valve; 810: and a third valve.
Detailed Description
For the purposes of making the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application are clearly and completely described below, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art without inventive effort, are also within the scope of the present application based on the embodiments herein.
Fig. 1 is a schematic structural diagram of a rectification system of 2, 4-difluoronitrobenzene according to an embodiment of the present application, and fig. 2 is a schematic structural diagram of a condenser according to an embodiment of the present application, as shown in fig. 1 and fig. 2, the present application provides a rectification system of 2, 4-difluoronitrobenzene, including: the rectifying tower 1, the condenser 2, the reflux drum 4 and the product tank 5 that communicate in proper order with the steam outlet of rectifying tower 1, reflux drum 4 still communicates through backwash pump 110 with the backward flow mouth of rectifying tower 1, and product tank 5 still communicates with negative pressure unit 6, and the feed inlet and the mother liquor storage tank of rectifying tower 1 pass through mother liquor pump 120 intercommunication.
The bottom discharge port of the rectifying tower 1 is communicated with the reboiler 7 through a tower kettle pump 130, the vapor outlet of the reboiler 7 is communicated with the vapor inlet of the rectifying tower 1, and the liquid outlet of the reboiler 7 and the bottom discharge port of the rectifying tower 1 are both communicated with the tower kettle liquid storage tank 8.
The condenser 2 is internally provided with a plurality of heat exchange tubes 210 which are distributed in parallel, a first screw rod 220 and a second screw rod 230 are symmetrically arranged between two adjacent heat exchange tubes 210 about the center of the heat exchange tube 210, and the screw thread directions of the first screw rod 220 and the second screw rod 230 are opposite.
Specifically, the mother liquor containing 2, 4-difluoronitrobenzene is pumped from a mother liquor storage tank to the inside of the rectifying tower 1 from a feed inlet positioned in the middle of the rectifying tower 1 through a mother liquor pump 120, structured packing is arranged in the rectifying tower 1, the mother liquor containing 2, 4-difluoronitrobenzene falls to the bottom of the rectifying tower 1 from top to bottom under the action of gravity through layer-by-layer packing, a tower kettle pump 130 and a negative pressure unit 6 are started, the mother liquor at the bottom of the rectifying tower 1 is conveyed to a reboiler 7, heating medium is introduced into the reboiler 7, the negative pressure unit 6 provides negative pressure for a rectifying system, so that the boiling point of 2, 4-difluoronitrobenzene is reduced, the addition of the heating medium is reduced, the energy consumption of the system is reduced, the 2, 4-difluoronitrobenzene is conveniently gasified into 2, 4-difluoronitrobenzene vapor after heat exchange with the heating medium, the 2, 4-difluoronitrobenzene vapor enters the rectifying tower 1 from a vapor inlet of the rectifying tower 1, and passes through the packing layers from bottom to top under the action of negative pressure, heat and mass exchange is carried out with the descending mother liquor, so that the 2, 4-difluoronitrobenzene in the 2, 4-nitrobenzene in the rectifying tower 2, 4-difluoronitrobenzene and 2, 4-nitrobenzene in the rectifying tower 2-4-2-dinitronitrobenzene vapor is continuously gasified from the top to the rectifying tower 1 by the pump and the heating medium is discharged to the vapor in the rectifying tower, and the vapor is continuously recycled to the rectifying tower 2-4-fluoronitrobenzene vapor, and the vapor is discharged from the rectifying tower 1 to the rectifying tower bottom to the rectifying tower 2, and the 2-dinitronitrobenzene vapor, and the 2-dinitrobenzene vapor is continuously recycled.
The gas phase 2, 4-difluoronitrobenzene discharged from the top of the rectifying tower 1 is condensed by a condenser 2 to obtain liquid phase 2, 4-difluoronitrobenzene, the liquid phase 2, 4-difluoronitrobenzene is conveyed into a reflux tank 4, a reflux pump 110 is started to convey part of the liquid phase 2, 4-difluoronitrobenzene in the reflux tank 4 to the rectifying tower 1 through a reflux port of the rectifying tower 1 for rectification again, and the 2, 4-difluoronitrobenzene product with higher purity is obtained through repeated reflux and rectification. The liquid phase 2, 4-difluoronitrobenzene which is not refluxed in the reflux drum 4 is fed to the product drum 5 for storage.
The reboiler 7 continuously heats and evaporates the tower bottom liquid of the rectifying tower 1, and part of the tower bottom liquid which is not evaporated is conveyed to a tower bottom liquid storage tank 8 for sewage treatment. Sampling and detecting at the top of the rectifying tower 1, when the content of 2, 4-difluoronitrobenzene is smaller than or equal to a preset content value, the content of 2, 4-difluoronitrobenzene in the mother liquor is too low, the purity requirement of the 2, 4-difluoronitrobenzene is not met, if the rectification is continued, resources are wasted, the quality of the obtained product is poor, the system operation is stopped, and the tower bottom liquid of the rectifying tower 1 is conveyed into a tower bottom liquid storage tank 8.
In the rectification process, the gas phase 2, 4-difluoronitrobenzene is condensed by a condenser 2, the condenser 2 is a tube type condenser, a plurality of heat exchange tubes 210 which are distributed in parallel are arranged in the condenser 2, condensate enters the heat exchange tubes 210, high-temperature gas phase 2, 4-difluoronitrobenzene moves between the heat exchange tubes 210, heat exchange is carried out inside and outside the heat exchange tubes 210, and the gas phase 2, 4-difluoronitrobenzene is condensed into liquid 2, 4-difluoronitrobenzene, so that the liquid 2, 4-difluoronitrobenzene is convenient to store and use. A first screw rod 220 and a second screw rod 230 are arranged between two adjacent heat exchange tubes 210, and the screw rods can enable condensate to change in direction when flowing, so that the condensate causes turbulence between the two adjacent heat exchange tubes 210, the heat exchange area is increased, and the condensation efficiency of gas phase 2, 4-difluoronitrobenzene is further improved. And the screw thread directions of the first screw 220 and the second screw 230 are opposite, so that when condensate flows in the axial direction in the condenser, the turbulence direction changes, the turbulence is stronger and stronger, the occurrence of a heat exchange dead zone in the condenser is avoided, the heat transfer effect is better, the condensation efficiency of the gas phase 2, 4-difluoronitrobenzene is improved, and the condensation effect is achieved without increasing the flow rate of the condensate or reducing the temperature of the condensate. Thus, the use of cold is reduced, resources are saved, and the production cost is reduced.
Through the scheme, the rectification of the 2, 4-difluoronitrobenzene is realized, the boiling point of the 2, 4-difluoronitrobenzene is reduced, the addition of a heat medium is reduced, the energy consumption of the system is reduced, and the 2, 4-difluoronitrobenzene is conveniently gasified into 2, 4-difluoronitrobenzene vapor after heat exchange with the heating medium. And part of liquid phase 2, 4-difluoronitrobenzene in the reflux tank is conveyed to the rectifying tower through a reflux port of the rectifying tower to be rectified again, and the 2, 4-difluoronitrobenzene product with higher purity is obtained through repeated reflux and rectification. Through setting up first hob and second hob between two adjacent heat exchange tubes, the hob can make the condensate take place the change of direction when flowing, and then makes the condensate arouse the torrent when flowing, increases heat transfer area, and then improves the condensation efficiency of gaseous phase 2, 4-difluoro nitrobenzene. And the screw thread direction of first screw rod and second screw rod are opposite for condensate turbulence direction changes, and turbulence is stronger and stronger, and the heat transfer effect is just also better, has improved the condensation efficiency of gaseous phase 2, 4-difluoro nitrobenzene, need not to reach the effect of condensation through the flow of increase condensate or reduction condensate's temperature. Thus, the use of cold is reduced, resources are saved, and the production cost is reduced.
Optionally, the ends of the first screw rod 220 and the second screw rod 230 near the two end heads of the condenser are fixedly connected with the plate tube 240, and the ends of the first screw rod 220 and the second screw rod 230 near the center of the condenser are fixedly connected with the inner wall of the condenser through the connecting rod 250.
Specifically, the spiral rod is arranged in such a way that the direction of flowing condensate is changed, turbulence is increased, the heat exchange area of gas phase 2, 4-difluoronitrobenzene and the condensate is increased, and the heat exchange effect is improved. Preferably, the end parts of the screw rods, which are close to the end heads at the two ends of the condenser, are fixedly connected with the plate pipe 240 through bolts, and the end parts of the screw rods, which are close to the center position of the condenser, are fixedly connected with the connecting rods 250 through bolts, so that the screw rods are convenient to detach and maintain.
Optionally, the direction of the cross section of the baffle 260 is perpendicular to the axial direction of the heat exchange tube 210.
Specifically, the baffle 260 is used for changing the flowing direction of the condensate, and the direction of the section where the plate surface of the baffle 260 is located is perpendicular to the axial direction of the heat exchange tube 210, and is also perpendicular to the flowing direction of the condensate, so that the arrangement can change the direction of the condensate to the greatest extent, and cooperates with the first screw rod 220 and the second screw rod 230 to increase the turbulence degree of the condensate, improve the heat exchange area, further avoid the occurrence of heat exchange dead zone in the condenser, and further improve the condensation efficiency of the gas phase 2, 4-difluoronitrobenzene.
Alternatively, the baffles 260 are straight or corrugated plates.
Specifically, the baffle plates 260 of the straight plate or the corrugated plate can both play a role in changing the direction of the fluid, and preferably, the baffle plates 260 are corrugated plates, the heat exchange area is larger than that of the straight plate, and the condensation effect is good.
Fig. 3 is a schematic structural diagram of a rectification system of 2, 4-difluoronitrobenzene according to another embodiment of the present application, and as shown in fig. 3, the rectification system is optionally further connected with a subcooler 3, and the subcooler 3 is in serial communication with the condenser 2.
The condensate inlet of the condenser 2 is communicated with the outlet of the mother liquor storage tank, and the condensate outlet of the condenser 2 is communicated with the feed inlet of the rectifying tower 1 through a mother liquor pump 120.
Specifically, as the temperature of the 2, 4-difluoronitrobenzene vapor discharged from the vapor outlet of the rectifying tower 1 is higher, the heat energy is provided, and the 2, 4-difluoronitrobenzene vapor with the heat energy is subjected to heat exchange with the mother liquor, so that the mother liquor has a certain heat before entering the rectifying tower 1, the temperature drop of the inside of the tower body and the 2, 4-difluoronitrobenzene vapor after entering the rectifying tower 1 can be reduced, a part of heat is prevented from being used for heating the mother liquor, and the heat consumption is reduced. Meanwhile, after 2, 4-difluoronitrobenzene vapor exchanges heat with mother liquor, liquid 2, 4-difluoronitrobenzene output by a condensate outlet of the condenser 2 and uncondensed gas phase 2, 4-difluoronitrobenzene enter a gas phase inlet of the recooler 3, condensation is continued in the recooler 3, and the obtained liquid 2, 4-difluoronitrobenzene is conveyed into the reflux tank 4, so that the condensation load of the recooler 3 is reduced, the use of condensate is reduced, the cold consumption is reduced, and the production cost is also reduced. Wherein the condensate in the subcooler 3 may be chilled brine or circulating water.
Alternatively, as shown in fig. 3, a pressure sensor 140 and a temperature sensor 150 are provided inside the top of the rectifying column 1.
Specifically, the pressure sensor 140 and the temperature sensor 150 are respectively used for detecting the pressure and the temperature in the rectifying tower 1, so that the pressure and the temperature are within preset values of the rectifying system, and smooth operation of the system is ensured.
Optionally, the negative pressure unit 6 is provided with a first valve 610, the heat medium inlet of the reboiler 7 is provided with a second valve 710, and the inlet of the tower kettle liquid storage tank 8 connected with the bottom discharge port of the rectifying tower 1 is provided with a third valve 810.
Specifically, the first valve 610 is used to adjust the negative pressure of the system to reduce the boiling point of 2, 4-difluoronitrobenzene. The second valve 710 is used to regulate the flow of the heat medium into the reboiler 7 so that the liquid 2, 4-difluoronitrobenzene is heated and gasified under negative pressure to form 2, 4-difluoronitrobenzene vapor, which facilitates distillation. The third valve 810 is used for delivering the tower bottom liquid in the rectifying tower 1 into the tower bottom liquid storage tank 8 after the rectification is finished.
Fig. 4 is a schematic diagram of connection of the controller according to an embodiment of the present application, as shown in fig. 4, optionally, the rectification system is provided with a controller 9, and the controller 9 is respectively connected to the first valve 610, the second valve 710, the third valve 810, the reflux pump 110, the mother liquor pump 120, the tower kettle pump 130, the pressure sensor 140 and the temperature sensor 150.
Specifically, the controller 9 adjusts the opening of the first valve 610, the opening of the second valve 710, and the power of the mother liquor pump 120 according to the pressure and temperature signals transmitted by the pressure sensor 140 and the temperature sensor 150, so that the system operates at a preset pressure and temperature, and the safe and efficient operation of the system is ensured. According to the detection of the content of 2, 4-difluoronitrobenzene by sampling at the top of the rectifying tower 1, when the content of 2, 4-difluoronitrobenzene is smaller than or equal to a preset content value, the controller 9 opens the third valve 810 to convey the tower bottom liquid of the rectifying tower 1 into the tower bottom liquid storage tank 8. At the same time, when the system starts to operate, the controller 9 starts the reflux pump 110 and the tower kettle pump 130 to operate normally.
The technical scheme of the present application is illustrated in detail by specific examples below.
The operation flow of the rectification system of 2, 4-difluoronitrobenzene in the embodiment in specific work is as follows:
when the rectification system is operated, the controller 9 starts the mother liquor pump 120, mother liquor containing 2, 4-difluoronitrobenzene is pumped from a mother liquor storage tank to the inside of the rectification tower 1 from a feed inlet positioned in the middle of the rectification tower 1 through the mother liquor pump 120, the inside 1 of the rectification tower is provided with structured packing, the mother liquor containing 2, 4-difluoronitrobenzene falls to the bottom of the rectification tower 1 from top to bottom under the action of gravity through the layer-by-layer packing, meanwhile, the tower kettle pump 130 and the negative pressure unit 6 are started, the mother liquor at the bottom of the rectification tower 1 is conveyed to the reboiler 7, heating medium is introduced into the reboiler 7, the negative pressure unit 6 provides negative pressure for the rectification system, the controller 9 adjusts the first valve 610 and the second valve 710, so that 2, 4-difluoronitrobenzene is gasified into 2, 4-difluoronitrobenzene vapor after heat exchange with the heating medium, the 2, 4-difluoronitrobenzene vapor enters the rectification tower 1 from the vapor inlet of the rectification tower 1, passes through the packing layers from bottom to top under the action of negative pressure, heat and quality exchange is carried out with the descending mother liquor, so that 2, 4-difluoronitrobenzene in the 2, 4-nitrobenzene part of the rectification tower top and 2, 4-dinitrobenzene vapor continuously falls to the bottom of the rectification tower 1 along with the vaporization of the vaporization mother liquor.
The gas phase 2, 4-difluoronitrobenzene discharged from the top of the rectifying tower 1 is condensed by a condenser 2 and a recooler 3 in sequence to obtain liquid phase 2, 4-difluoronitrobenzene, and the liquid phase 2, 4-difluoronitrobenzene is conveyed into a reflux tank 4. The condensate inlet of the condenser 2 is communicated with the outlet of the mother liquor storage tank, and the condensate outlet of the condenser 2 is communicated with the feed inlet of the rectifying tower 1 through a mother liquor pump 120. The mother liquor is used as condensate of the condenser 2, and the condensate of the subcooler 3 can be chilled brine. The controller 9 starts the reflux pump 110 to convey part of liquid phase 2, 4-difluoronitrobenzene in the reflux tank 4 to the rectifying tower 1 through the reflux port of the rectifying tower 1 for rectification again, and the 2, 4-difluoronitrobenzene product with higher purity is obtained after multiple reflux and rectification. The liquid phase 2, 4-difluoronitrobenzene which is not refluxed in the reflux drum 4 is fed to the product drum 5 for storage. When the controller 9 receives the pressure signal transmitted by the pressure sensor 140 and is greater than or equal to the preset pressure value, the first valve 610 is turned down, and when the controller 9 receives the temperature signal transmitted by the temperature sensor 150 and is greater than or equal to the preset temperature value, the controller 9 turns down the opening of the second valve 710 and/or controls to increase the power of the mother liquor pump 120, increase the flow of the mother liquor entering the tower and reduce the temperature at the top of the tower.
The reboiler 7 continuously heats and evaporates the tower bottom liquid of the rectifying tower 1, and part of the tower bottom liquid which is not evaporated is conveyed to a tower bottom liquid storage tank 8 for sewage treatment. Sampling and detecting at the top of the rectifying tower 1, when the content of the 2, 4-difluoronitrobenzene is smaller than or equal to a preset content value, the content of the 2, 4-difluoronitrobenzene in the mother liquor is too low, the purity requirement of the 2, 4-difluoronitrobenzene is not met, the system operation is stopped, a third valve 810 is opened, and the tower bottom liquid of the rectifying tower 1 is conveyed into a tower bottom liquid storage tank 8.
Finally, it should be noted that the above embodiments are merely for illustrating the technical solution of the present application, and are not limiting; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art will understand; the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.
Claims (8)
1. A rectification system for 2, 4-difluoronitrobenzene, comprising: the device comprises a rectifying tower (1), a condenser (2), a reflux tank (4) and a product tank (5), wherein the condenser (2), the reflux tank (4) and the product tank (5) are sequentially communicated with a steam outlet of the rectifying tower (1), the reflux tank (4) is also communicated with a reflux port of the rectifying tower (1) through a reflux pump (110), the product tank (5) is also communicated with a negative pressure unit (6), and a feed port of the rectifying tower (1) is communicated with a mother liquor storage tank through a mother liquor pump (120);
the bottom discharge port of the rectifying tower (1) is communicated with a reboiler (7) through a tower kettle pump (130), the vapor outlet of the reboiler (7) is communicated with the vapor inlet of the rectifying tower (1), and the liquid outlet of the reboiler (7) and the bottom discharge port of the rectifying tower (1) are both communicated with a tower kettle liquid storage tank (8);
the condenser is characterized in that a plurality of heat exchange tubes (210) which are distributed in parallel are arranged in the condenser (2), a first screw rod (220) and a second screw rod (230) are symmetrically arranged between two adjacent heat exchange tubes (210) in a left-right mode with respect to the center of the heat exchange tube (210), and the screw thread directions of the first screw rod (220) and the screw thread direction of the second screw rod (230) are opposite.
2. The rectification system of 2, 4-difluoronitrobenzene according to claim 1, wherein the ends of the first screw rod (220) and the second screw rod (230) close to the end heads at the two ends of the condenser are fixedly connected with a plate pipe (240), and the ends of the first screw rod (220) and the second screw rod (230) close to the central position of the condenser are fixedly connected with the inner wall of the condenser through a connecting rod (250).
3. The rectification system as recited in claim 1, wherein a baffle (260) is fixedly arranged on the outer wall of the heat exchange tube (210), and the direction of the section where the baffle (260) is positioned is perpendicular to the axial direction of the heat exchange tube (210).
4. A rectification system for 2, 4-difluoronitrobenzene according to claim 3, wherein said baffle (260) is a straight or corrugated plate.
5. Rectification system of 2, 4-difluoronitrobenzene according to claim 1, characterized in that it is further connected with a sub-cooler (3), said sub-cooler (3) being in series communication with said condenser (2);
the condensate inlet of the condenser (2) is communicated with the outlet of the mother liquor storage tank, and the condensate outlet of the condenser (2) is communicated with the feed inlet of the rectifying tower (1) through a mother liquor pump (120).
6. The rectification system of 2, 4-difluoronitrobenzene according to any one of claims 1 to 5, characterized in that a pressure sensor (140) and a temperature sensor (150) are arranged inside the top of the rectification column (1).
7. The rectifying system of 2, 4-difluoronitrobenzene according to claim 6, characterized in that the negative pressure unit (6) is provided with a first valve (610), the heat medium inlet of the reboiler (7) is provided with a second valve (710), and the inlet of the tower bottom liquid storage tank (8) connected with the bottom discharge port of the rectifying tower (1) is provided with a third valve (810).
8. The rectification system according to claim 7, wherein the rectification system is provided with a controller (9), the controller (9) being connected to the first valve (610), the second valve (710), the third valve (810), the reflux pump (110), the mother liquor pump (120), the bottoms pump (130), the pressure sensor (140) and the temperature sensor (150), respectively.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117582684A (en) * | 2024-01-19 | 2024-02-23 | 大庆亿鑫化工股份有限公司 | Extraction element for production industrial alkane cleaner |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117582684A (en) * | 2024-01-19 | 2024-02-23 | 大庆亿鑫化工股份有限公司 | Extraction element for production industrial alkane cleaner |
| CN117582684B (en) * | 2024-01-19 | 2024-03-29 | 大庆亿鑫化工股份有限公司 | Extraction element for production industrial alkane cleaner |
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