CN111285783B - Refining and purifying system and method for high-content chlorothalonil - Google Patents
Refining and purifying system and method for high-content chlorothalonil Download PDFInfo
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- CN111285783B CN111285783B CN201811487157.6A CN201811487157A CN111285783B CN 111285783 B CN111285783 B CN 111285783B CN 201811487157 A CN201811487157 A CN 201811487157A CN 111285783 B CN111285783 B CN 111285783B
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Abstract
The invention provides a refining and purifying system and a refining and purifying method for high-content chlorothalonil. The method comprises the following steps: after being melted, the crude chlorothalonil product is sent into a rectification unit for rectification, and low-boiling impurities are evaporated from the top of a rectification tower and then desublimated into solid; and distilling out the chlorothalonil from the rectifying still, condensing and slicing to obtain the refined chlorothalonil. According to the invention, low-boiling-point substances such as hexachlorobenzene and the like and high-boiling-point substances such as tetrachloroterephthalonitrile and the like in the chlorothalonil are removed by adopting a rectification process, so that the further refining and purification of the chlorothalonil are realized, and a high-quality chlorothalonil product with the chlorothalonil content of more than or equal to 99% and the hexachlorobenzene content of less than or equal to 5ppm is obtained.
Description
Technical Field
The invention belongs to the field of product refining, relates to a system and a method for refining and purifying chlorothalonil, and particularly relates to a system and a method for refining and purifying high-content chlorothalonil.
Background
Chlorothalonil is a high-efficiency, low-toxicity, broad-spectrum and low-residue protective bactericide, is widely used for preventing and treating fungal diseases in agriculture and forestry, and is particularly widely applied to economic crops such as vegetables, fruits and the like. According to the report of related data, chlorothalonil has control effect on fifty-two diseases of more than thirty crops. In addition, chlorothalonil has important applications in the field of mildew-proof industry, such as manufacturing mildew-proof coatings and mildew-proof wallpaper, and mildew prevention of electrical appliances, leather, wood and the like. The domestic production scale of chlorothalonil is continuously enlarged, the chlorothalonil becomes one of large-tonnage excellent pesticide varieties in the world, and the chlorothalonil is sold in the international market all the time. Chlorothalonil is defined as white powder in national standard GB/T9551-2017 of China, and the two main indexes comprise that the content of chlorothalonil is more than or equal to 97 percent and the content of hexachlorobenzene is less than or equal to 40ppm. The international market at present obviously improves the internal quality requirement of chlorothalonil, particularly emphasizes higher requirement on the control of harmful substance Hexachlorobenzene (HCB) besides content and appearance, and the hexachlorobenzene is not easy to degrade and has serious harm to the environment. The international market requires that the content of the chlorothalonil is less than 10ppm, and the research and the development of the chlorothalonil product with the hexachlorobenzene content of less than or equal to 10ppm are imminent, so that the international market is occupied, and the national call for green environmental protection chemistry is responded, so that the production of the chlorothalonil original drug with the hexachlorobenzene content of less than 10ppm has important social significance and economic value.
At present, the related technical documents for refining and purifying chlorothalonil in China are few, and the method for refining chlorothalonil by adopting toluene recrystallization is adopted, wherein toluene is used as a solvent, solid-liquid separation is carried out after heating and dissolving, the liquid phase part is condensed and crystallized, then solid-liquid separation is carried out again, a product is obtained after solid phase drying, and the solvent is recycled after the liquid phase is distilled. The method has the main defects of high VOC (volatile organic compounds) emission and solid waste generation amount, unstable product quality and easy generation of chlorothalonil products with hexachlorobenzene content higher than 10ppm.
CN108329235A discloses a process for producing high-purity chlorothalonil, which comprises the steps of feeding raw materials containing chlorothalonil isophthalonitrile, trichloroisophthalonitrile, pentachlorobenzonitrile, hexachlorobenzene and water into a light component removal tower, collecting a mixture consisting of chlorothalonil with the light component mass content of less than or equal to 0.01% and heavy components at the bottom of the light component removal tower, feeding the mixture into a product tower, and collecting a chlorothalonil product with the mass fraction of more than or equal to 99.5% from the top of the product tower. The distillation process is adopted to refine the chlorothalonil, the operation process is simple, and the chlorothalonil product with the mass fraction of more than 99.5 percent can be obtained. However, the method adopts continuous rectification to refine and purify chlorothalonil, needs two groups of rectifying towers, not only provides the investment cost of equipment, but also is not beneficial to industrialized popularization, and has small operation flexibility and operable space.
CN100404500C discloses a production method of chlorothalonil with low hexachlorobenzene content, which comprises the steps of completely vaporizing isophthalonitrile, carrying out a first-step reaction on the isophthalonitrile out of a vaporizer by using nitrogen, mixing the isophthalonitrile with chlorine, then feeding the mixture into a fluidized bed for a first-step reaction, mixing a reaction product with the chlorine again, feeding the mixture into a fixed bed for chlorination, and condensing and collecting output mixed gas to obtain a chlorothalonil product. The invention can conveniently adjust the reaction load of the reactor, accurately control the content of hexachlorobenzene in the product, and greatly improve the pH value and the main content of the finished product. The method is simple and convenient to operate, low in cost, clean and environment-friendly in production process and emission, and has good market application prospect. However, it can be seen from the description of the examples in this application that the chlorothalonil product prepared by this process still contains more than 10ppm of hexachlorobenzene.
At present, the chlorothalonil product produced by using a conventional production process can rarely meet the requirement that the content of hexachlorobenzene is lower than 10ppm, but in order to reduce the harm of hexachlorobenzene in the chlorothalonil to the environment and soil, the chlorothalonil product conforms to the strict standard of the international market for the chlorothalonil more, occupies the international market, and needs to be refined to further reduce the content of hexachlorobenzene in the chlorothalonil, so that a high-quality chlorothalonil product with higher quality and lower content of hexachlorobenzene is produced.
Disclosure of Invention
The invention aims to provide a refining and purifying system and a refining and purifying method for high-content chlorothalonil, wherein after the chlorothalonil crude product is melted, low-boiling-point substances such as hexachlorobenzene and the like and high-boiling-point substances such as tetrachloroterephthalonitrile and the like in the chlorothalonil crude product are removed by adopting a rectifying tower intermittent rectification method, so that a high-quality chlorothalonil product with the chlorothalonil content of more than or equal to 99 percent and the hexachlorobenzene content of less than or equal to 5ppm is obtained.
In order to achieve this object, the invention adopts the following technical scheme:
in a first aspect, the invention provides a refining and purifying system for high-content chlorothalonil, which comprises a feeding unit, a rectifying unit, a condensing unit and a trapping unit which are connected in sequence.
The rectifying unit comprises a first rectifying kettle, a second rectifying kettle and a rectifying tower; the top discharge port of the first rectifying kettle and the top discharge port of the second rectifying kettle are connected with the lower feed port of the rectifying tower, the upper return port of the first rectifying kettle and the upper return port of the second rectifying kettle are connected with the bottom return port of the rectifying tower, and the upper feed ports of the first rectifying kettle and the second rectifying kettle are connected with the discharge port of the feeding unit.
The condensation unit comprises a condensation device and a product receiving kettle which are communicated from top to bottom, wherein a top air inlet of the condensation device is connected with top air outlets of the first rectifying kettle and the second rectifying kettle, and a discharge port for connecting a slicing machine is arranged at the bottom of the product receiving kettle.
The invention further removes dangerous wastes such as hexachlorobenzene in the high-content chlorothalonil by adopting a batch rectification process method, prepares a refined chlorothalonil product with the hexachlorobenzene content lower than 5ppm, and can stably produce high-quality chlorothalonil products in a large scale.
As a preferred technical scheme, the system also comprises a vacuum extractor connected with the trapping unit.
Preferably, the feeding unit includes a hopper, a conveying device, and a melting device, which are connected in sequence.
Preferably, the conveying device is a screw conveyor.
Preferably, the trapping unit comprises a first trapping device and a second trapping device, the tops of the first trapping device and the second trapping device are respectively provided with a first feeding hole, a second feeding hole and an air extraction opening, the first feeding hole is connected with a discharging hole in the upper portion of the product receiving kettle, the second feeding hole is connected with a top extraction opening of the rectifying tower, and the air extraction opening is connected with the vacuumizing device.
Preferably, the cavity of the first trapping device and the cavity of the second trapping device are in a single-layer or double-layer jacket structure;
preferably, water or air is introduced into the double-layer jacket.
In a second aspect, the present invention provides a method for refining and purifying high-content chlorothalonil, wherein the method is performed in the system of the first aspect, and the method comprises the following steps:
and (3) after melting the high-content chlorothalonil crude product, sending the high-content chlorothalonil crude product into a rectification unit for rectification, evaporating low-boiling impurities from the top of a rectification tower for desublimation, evaporating gaseous chlorothalonil from a rectification kettle, and slicing after condensation to obtain refined chlorothalonil.
The invention introduces the high-content chlorothalonil crude product into a rectification unit, further rectifies and purifies the chlorothalonil crude product, separates out low-boiling impurities of hexachlorobenzene, monochloro-m-phthalonitrile, dichlorom-phthalonitrile, trichloro-m-phthalonitrile and pentachlorobenzonitrile in the chlorothalonil crude product from the top of a rectification tower, and sublimates the low-boiling impurities into solid in a catcher to be bagged. And the chlorothalonil product is steamed out from the rectifying still, is changed into liquid through the condenser and enters the product receiving still, and then the liquid chlorothalonil product is sliced through a slicer to obtain a final solid flaky chlorothalonil refined product. Residual tetrachloroterephthalonitrile, mechanical impurities and other high-boiling substances in the rectifying still are discharged and barreled to be used as solid waste for subsequent treatment.
As a preferred technical scheme of the invention, the crude chlorothalonil product comprises chlorothalonil and hexachlorobenzene, wherein the content of the chlorothalonil is 90-99.5%, for example 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99%, and the content of the hexachlorobenzene is 10-100ppm, for example 10ppm, 20ppm, 30ppm, 40ppm, 50ppm, 60ppm, 70ppm, 80ppm, 90ppm or 100ppm. The intermittent rectification operation adopted by the invention has larger operation flexibility, the content of the chlorothalonil in the crude product of the chlorothalonil can fluctuate in a larger range, and high-quality chlorothalonil products can be stably produced.
Preferably, the low-boiling impurities are one or a combination of two or more of hexachlorobenzene, monochlorodiphthalonitrile, dichloroisophthalonitrile, trichloroisophthalonitrile or pentachlorobenzonitrile, a typical but non-limiting combination being hexachlorobenzene and monochlorodiphthalonitrile, hexachlorobenzene and dichloroisophthalonitrile, hexachlorobenzene and trichloroisophthalonitrile or hexachlorobenzene and pentachlorobenzonitrile.
As a preferred embodiment of the present invention, the melting is performed in a melting tank.
Preferably, the melting kettle is heated by using heat conduction oil.
Preferably, the temperature of the heat transfer oil is 260-350 ℃, for example, 260 ℃, 270 ℃, 280 ℃, 290 ℃, 300 ℃, 310 ℃, 320 ℃, 330 ℃, 340 ℃ or 350 ℃, preferably 300-330 ℃.
As a preferred technical scheme of the invention, the rectification is carried out at high temperature.
Preferably, the rectification unit is heated using conduction oil.
Preferably, the temperature of the heat conducting oil is 260-350 ℃, for example, 260 ℃, 270 ℃, 280 ℃, 290 ℃, 300 ℃, 310 ℃, 320 ℃, 330 ℃, 340 ℃ or 350 ℃, preferably 300-330 ℃.
Preferably, the rectification is performed alternately in the first rectifying still and the second rectifying still. When first rectifying still carries out the rectification operation, the sediment is arranged to the completion of second rectifying still, and after first rectifying still rectification was accomplished, the switching through pipeline and valve lets in the material and continues the rectification in arranging the second rectifying still after sediment finishes, and first rectifying still arranges the sediment this moment to realize serialization rectification operation.
Preferably, the rectifying tower is divided into an upper section and a lower section for heating, and the heating temperature of the lower section is 300-350 ℃, for example, 300 ℃, 310 ℃, 320 ℃, 330 ℃, 340 ℃ or 350 ℃, preferably 320-330 ℃; the temperature of the upper stage is 260-330 ℃, for example 260 ℃, 270 ℃, 280 ℃, 290 ℃, 300 ℃, 310 ℃, 320 ℃ or 330 ℃, preferably 280-300 ℃.
Preferably, the temperature of the condenser at the top of the rectification column is 260 to 330 ℃, for example 260 ℃, 270 ℃, 280 ℃, 290 ℃, 300 ℃, 310 ℃, 320 ℃ or 330 ℃, preferably 280 to 300 ℃.
As a preferred technical scheme of the invention, the rectification is carried out under negative pressure. And completely pumping the liquid chlorothalonil in the melting kettle into a rectifying kettle through system vacuum to carry out rectification operation.
Preferably, the degree of vacuum of the rectification unit is 0.085 to 0.098MPa, and may be, for example, 0.085MPa, 0.086MPa, 0.087MPa, 0.088MPa, 0.089MPa, 0.090MPa, 0.091MPa, 0.092MPa, 0.093MPa, 0.094MPa, 0.095MPa, 0.096MPa, 0.097MPa or 0.098MPa, preferably 0.09 to 0.095MPa.
As a preferred embodiment of the invention, the desublimation is carried out in a capture unit.
Preferably, the desublimation is performed alternately in the first and second trapping devices.
Preferably, the temperature of the first and second collection devices is 30 to 100 ℃, and may be 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃ or 100 ℃.
As the preferable technical scheme of the invention, the chlorothalonil is condensed and then enters a product receiving kettle.
Preferably, the condensed condensing medium is heat conducting oil, and the temperature of the heat conducting oil is 260-300 ℃, for example, 260 ℃, 270 ℃, 280 ℃, 290 ℃ or 300 ℃, preferably 260-270 ℃.
Preferably, the product receiving vessel is heated using a heat transfer oil at a temperature of 260-300 deg.C, such as 260 deg.C, 270 deg.C, 280 deg.C, 290 deg.C, or 300 deg.C, preferably 260-270 deg.C.
In a third aspect, the present invention provides a purified chlorothalonil obtained by a process as defined in the second aspect.
Preferably, the content of the refined chlorothalonil is not less than 99%, and may be, for example, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8% or 99.9%.
Preferably, the purified chlorothalonil has a hexachlorobenzene content of 5ppm or less, and may be, for example, 5ppm, 4.5ppm, 4ppm, 3.5ppm, 3ppm, 2.5ppm, 2ppm, 1.5ppm, 1ppm or 0.5ppm.
The recitation of numerical ranges herein includes not only the above-recited numerical values, but also any numerical values between non-recited numerical ranges, and is not intended to be exhaustive or to limit the invention to the precise numerical values encompassed within the range for brevity and clarity.
Compared with the prior art, the invention has the following beneficial effects:
the invention solves the problem that the prior art can not stably produce the chlorothalonil product with extremely low hexachlorobenzene content by an intermittent rectification process, and the process method provided by the invention has low requirement on the range of the chlorothalonil content in the crude product, and the chlorothalonil content can fluctuate in a larger range. The rectification process provided by the invention can be used for producing high-quality chlorothalonil products with chlorothalonil content of more than or equal to 99% and hexachlorobenzene content of less than or equal to 5ppm, the rectification yield is over 97%, and the high-quality chlorothalonil product not only meets the environmental concept of environmental protection, but also reaches the strict standard of the international market on the chlorothalonil products.
Drawings
FIG. 1 is a process flow diagram provided by an embodiment of the present invention.
Wherein: 1-a storage bin; 2-a screw conveyor; 3-melting kettle; 4-a first rectifying still; 5-a second rectifying still; 6-a rectifying tower; 7-a condenser; 8-a product receiving kettle; 9-a first trap; 10-a second trap; 11-a first vacuum pump; 12-a second vacuum pump; V1-V2, va 1-Va 6 and Vb 1-Vb 6-valves.
Detailed Description
The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.
Example 1
The embodiment provides a refining and purifying system with high content of chlorothalonil, which comprises a feeding unit, a rectifying unit, a condensing unit, a capturing unit and a vacuumizing unit which are connected in sequence, as shown in figure 1.
The feeding unit comprises a silo 1, a screw conveyor 2 and a melting kettle 3 which are connected in sequence.
The rectifying unit includes first rectifying still 4, second rectifying still 5 and rectifying column 6, the top discharge gate of first rectifying still 4 and second rectifying still 5 is connected with the lower part feed inlet of rectifying column 6 through valve Va1 and valve Vb1 respectively, the upper portion feed back mouth of first rectifying still 4 and second rectifying still 5 is connected with the bottom feed back mouth of rectifying column 6 through valve Va3 and valve Vb3 respectively, the upper portion feed inlet of first rectifying still 4 and second rectifying still 5 is connected with the bottom discharge gate of melting cauldron 3 through valve Va4 and valve Vb4 respectively.
A valve V1 is also arranged on a connecting pipeline of the feeding unit and the rectifying unit.
The condensing unit comprises a condenser 7 and a product receiving kettle 8 which are communicated up and down; the top air inlet of condenser 7 passes through valve Va2 and valve Vb2 and connects the top gas outlet of first rectifying still 4 and second rectifying still 5 respectively, 8 bottoms of cauldron are received to the product are equipped with the discharge gate that is used for connecting the slicer.
The evacuation unit includes a first vacuum pump 11 and a second vacuum pump 12.
The trapping unit comprises a first trap 9 and a second trap 10, wherein the tops of the first trap 9 and the second trap 10 are respectively provided with a first feeding hole, a second feeding hole and an air pumping hole; a first feed inlet of the first catcher 9 is connected with a discharge outlet at the upper part of the product receiving kettle 8 through a valve Va6, a second feed inlet of the first catcher 9 is connected with a top extraction outlet of the rectifying tower 6 through a valve Va5, and an air suction port of the first catcher 9 is connected with a first vacuum pump 11; the first feed inlet of the second catcher 10 is connected with the discharge outlet at the upper part of the product receiving kettle 8 through a valve Vb6, the second feed inlet of the second catcher 10 is connected with the top extraction outlet of the rectifying tower 6 through a valve Vb5, and the pumping hole of the second catcher 10 is connected with a second vacuum pump 12. The cavities of the first catcher 9 and the second catcher 10 are of a single-layer structure.
And a valve V2 is also arranged on a connecting pipeline of the trapping unit and the rectifying unit.
Example 2
The difference from the embodiment 1 is that the cavities of the first catcher 9 and the second catcher 10 are of a double-layer jacket structure, and circulating water is introduced into the jacket. Other devices and their connection relation are the same as those of embodiment 1.
Example 3
The difference from the embodiment 1 is that the cavities of the first catcher 9 and the second catcher 10 are of a double-layer jacket structure, and cold air is introduced into the jacket. The other devices and their connection relationship are the same as those in embodiment 1.
Example 4
This embodiment provides a method for refining and purifying high-content chlorothalonil by using the purification system provided in embodiment 2, where the method specifically includes the following steps:
(1) Starting a first vacuum pump 11, opening a valve V2 of the rectifying tower 6 and a valve Va5 of a first catcher 9, and pumping the vacuum degree in the rectifying unit to 0.09MPa;
(2) 3 tons of high-content chlorothalonil raw pesticide containing 97.2 percent of chlorothalonil and 46ppm of hexachlorobenzene are put into a stock bin 1 and are sent into a melting kettle 3 through a screw conveyor 2, the melting kettle 3 is heated by adopting heat conduction oil, the oil temperature is 330 ℃, the materials in the kettle are completely melted, and the temperature in the kettle is controlled at 275 ℃;
(3) Opening a valve V1 of the melting kettle 3 and a valve Va4 of the rectifying kettle 4, pumping the materials in the melting kettle 3 into the first rectifying kettle 4 under the action of negative pressure, and closing the valves V1 and Va4 after the materials in the kettles are evacuated; heating the first rectifying kettle 4 by heat conducting oil, wherein the oil temperature is 330 ℃, and the temperature in the kettle is controlled at 295 ℃;
(4) Opening valves Va1 and Va3 of a first rectifying still 4, opening oil inlet valves of a rectifying tower 6 body and a tower top reflux condenser, and starting to rectify and cut low-boiling-point substances before rectification and cutting;
(5) The screw conveyor 2 is started, feeding is continuously carried out in the melting kettle 3, the melting kettle 3 is heated by adopting heat conduction oil, the oil temperature is 330 ℃, the materials in the kettle are completely melted, the temperature in the kettle is controlled at 275 ℃, and feeding is stopped after 3 tons of solid chlorothalonil products are completely melted;
(6) Opening a second vacuum pump 12 and a valve Vb6 of a second catcher 10, and pumping the vacuum degree in the product receiving kettle 8 to 0.09MPa;
(7) The temperature of a condenser at the top of the rectifying tower 6 is controlled to be 285 ℃, the temperature of the lower section of the tower body is controlled to be 320 ℃, the temperature of the upper section of the tower body is controlled to be 290 ℃, front fraction is gradually distilled out, when the distilled amount of the current fraction reaches 2 percent, the material of the first rectifying kettle 4 is taken for carrying out hexachlorobenzene content analysis, and if the hexachlorobenzene content is more than 5ppm, the front fraction is continuously extracted;
(8) If the content of hexachlorobenzene is less than or equal to 5ppm, closing valves Va3 and Va1 of the first rectifying still 4, closing an oil inlet valve of a top reflux condenser of the rectifying tower 6, and pumping the residual materials in the rectifying tower 6 into a first catcher 9;
(9) Opening a valve Va2 at the top of a first rectifying still 4, distilling the liquid material in the first rectifying still 4, feeding the liquid material into a condenser 7, condensing the liquid material, feeding the condensed liquid material into a product receiving still 8, feeding the condensed liquid material into a slicing machine under the action of a position difference, slicing and bagging the condensed liquid material to obtain a solid refined chlorothalonil product, and heating the condenser 7 and the product receiving still 8 through heat conduction oil, wherein the oil temperature of the heat conduction oil is 270 ℃;
(10) After the residual materials in the rectifying tower 6 are pumped into the first catcher 9, cooling oil is fed into the reflux condenser at the top of the tower, valves Vb4 and Vb1 of the second rectifying kettle 5 are opened, the materials in the melting kettle 3 are pumped into the second rectifying kettle 5, and the same rectifying operation as that of the first rectifying kettle 4 is repeated;
(11) After the distillation of the first rectifying still 4 is finished, closing a valve Va2 of the first rectifying still 4, a valve Vb6 of the second catcher 10 and a second vacuum pump 12, discharging residues in the first rectifying still 4 for barreling, and repeating the steps (3) - (9) after the residue discharge is finished;
the materials in the first catcher 9 and the second catcher 10 and the unqualified chlorothalonil production materials are combined into unqualified chlorothalonil materials, and the refining and purification process of the unqualified chlorothalonil is carried out. The chlorothalonil rectification residues are treated as solid waste.
And (3) sampling and analyzing the refined chlorothalonil extracted from the product receiving kettle, detecting the content of the chlorothalonil and the content of hexachlorobenzene, and calculating the rectification yield and the percentage of solid waste in the rectification raw material, wherein the related data are shown in a table 1.
Example 5
The difference from the example 4 is that the content of chlorothalonil in the high-content product is 90.1 percent, the content of hexachlorobenzene is 99ppm, the vacuum degree of a rectifying unit is changed to 0.085MPa, and other technological operating parameters are the same as those in the example 4.
And (3) sampling and analyzing the refined chlorothalonil extracted from the product receiving kettle, detecting the content of the chlorothalonil and the content of hexachlorobenzene, and calculating the rectification yield and the percentage of solid waste in the rectification raw material, wherein the related data are shown in a table 1.
Example 6
The difference from the example 4 is that the content of chlorothalonil in the high-content product is 90.1 percent, the content of hexachlorobenzene is 99ppm, the vacuum degree of a rectifying unit is changed to 0.098MPa, and other process operating parameters are the same as those in the example 4.
The refined chlorothalonil extracted from the product receiving kettle is sampled and analyzed, the content of chlorothalonil and the content of hexachlorobenzene in the refined chlorothalonil are detected, the rectification yield and the percentage of solid waste in the rectification raw material are calculated, and relevant data are shown in a table 1.
Example 7
The difference from the embodiment 4 is that the high-content product contains 95.0 percent of chlorothalonil, 63ppm of hexachlorobenzene, the temperature of the condenser at the top of the rectifying tower is changed to 260 ℃, the temperature control of the lower section of the tower body is changed to 300 ℃, the temperature control of the upper section of the tower body is changed to 260 ℃, and other technological operating parameters are the same as those in the embodiment 4.
And (3) sampling and analyzing the refined chlorothalonil extracted from the product receiving kettle, detecting the content of the chlorothalonil and the content of hexachlorobenzene, and calculating the rectification yield and the percentage of solid waste in the rectification raw material, wherein the related data are shown in a table 1.
Example 8
The difference from the example 4 is that the high-content product contains 99.5 percent of chlorothalonil, 12ppm of hexachlorobenzene, the temperature of the condenser at the top of the rectifying tower is changed to 330 ℃, the temperature control at the lower section of the tower body is changed to 350 ℃, the temperature control at the upper section of the tower body is changed to 330 ℃, and other technological operating parameters are the same as those in the example 4.
And (3) sampling and analyzing the refined chlorothalonil extracted from the product receiving kettle, detecting the content of the chlorothalonil and the content of hexachlorobenzene, and calculating the rectification yield and the percentage of solid waste in the rectification raw material, wherein the related data are shown in a table 1.
Example 9
The difference from the example 4 is that the content of chlorothalonil in the high-content product is 95.0 percent, the content of hexachlorobenzene is 63ppm, the oil temperature of the heat-conducting oil in the rectifying still is changed to 260 ℃, and other technological operating parameters are the same as those in the example 4.
The refined chlorothalonil extracted from the product receiving kettle is sampled and analyzed, the content of chlorothalonil and the content of hexachlorobenzene in the refined chlorothalonil are detected, the rectification yield and the percentage of solid waste in the rectification raw material are calculated, and relevant data are shown in a table 1.
Example 10
The difference from the example 4 is that the content of chlorothalonil in the high-content product is 93.6%, the content of hexachlorobenzene is 78ppm, the oil temperature of the heat-conducting oil in the rectifying still is changed to 350 ℃, and other technological operating parameters are the same as those in the example 4.
And (3) sampling and analyzing the refined chlorothalonil extracted from the product receiving kettle, detecting the content of the chlorothalonil and the content of hexachlorobenzene, and calculating the rectification yield and the percentage of solid waste in the rectification raw material, wherein the related data are shown in a table 1.
Example 11
The difference from the example 4 is that the content of the chlorothalonil in the high-content product is 97.2 percent, the content of the hexachlorobenzene is 46ppm, the temperature of the heat transfer oil in the condenser and the product receiving kettle is 260 ℃, and other technological operating parameters are the same as those in the example 4.
And (3) sampling and analyzing the refined chlorothalonil extracted from the product receiving kettle, detecting the content of the chlorothalonil and the content of hexachlorobenzene, and calculating the rectification yield and the percentage of solid waste in the rectification raw material, wherein the related data are shown in a table 1.
Example 12
The difference from the example 4 is that the content of chlorothalonil in the high-content product is 97.2 percent, the content of hexachlorobenzene is 46ppm, the temperature of the heat transfer oil in the condenser and the product receiving kettle is 270 ℃, and other technological operating parameters are the same as those in the example 4.
And (3) sampling and analyzing the refined chlorothalonil extracted from the product receiving kettle, detecting the content of the chlorothalonil and the content of hexachlorobenzene, and calculating the rectification yield and the percentage of solid waste in the rectification raw material, wherein the related data are shown in a table 1.
Example 13
The difference from the example 4 is that the content of the chlorothalonil in the high-content product is 97.2 percent, the content of the hexachlorobenzene is 46ppm, the temperature of the heat transfer oil in the condenser and the product receiving kettle is 290 ℃, and other process operating parameters are the same as those in the example 4.
The refined chlorothalonil extracted from the product receiving kettle is sampled and analyzed, the content of chlorothalonil and the content of hexachlorobenzene in the refined chlorothalonil are detected, the rectification yield and the percentage of solid waste in the rectification raw material are calculated, and relevant data are shown in a table 1.
Example 14
The difference from the example 4 is that the content of the chlorothalonil in the high-content product is 97.2 percent, the content of the hexachlorobenzene is 46ppm, the temperature of the heat transfer oil in the condenser and the product receiving kettle is 300 ℃, and other process operating parameters are the same as those in the example 4.
And (3) sampling and analyzing the refined chlorothalonil extracted from the product receiving kettle, detecting the content of the chlorothalonil and the content of hexachlorobenzene, and calculating the rectification yield and the percentage of solid waste in the rectification raw material, wherein the related data are shown in a table 1.
Example 15
The difference from the embodiment 4 lies in that the content of chlorothalonil in the high-content product is 96.4%, the content of hexachlorobenzene is 55ppm, the vacuum degree of the rectifying unit is changed to 0.095MPa, the oil temperature of the rectifying kettle is changed to 320 ℃, the temperature of a condenser at the top of the rectifying tower is changed to 280 ℃, the temperature control of the lower section of the tower body is changed to 330 ℃, the temperature control of the upper section of the tower body is changed to 300 ℃, and other technological operating parameters are the same as those of the embodiment 4.
The refined chlorothalonil extracted from the product receiving kettle is sampled and analyzed, the content of chlorothalonil and the content of hexachlorobenzene in the refined chlorothalonil are detected, the rectification yield and the percentage of solid waste in the rectification raw material are calculated, and relevant data are shown in a table 1.
Comparative example 1
The raw material (chlorothalonil product containing 95.2 percent of chlorothalonil) disclosed in CN108329235A in example 1 is replaced by a high-content chlorothalonil product containing 90.2 percent of chlorothalonil, and other process operation parameters are the same as those in example 1 disclosed in CN 108329235A.
The prepared refined chlorothalonil was sampled and analyzed, the chlorothalonil content and the hexachlorobenzene content therein were detected, and the distillation yield and the percentage of solid waste in the amount of the raw material for distillation were calculated, and the relevant data are shown in table 1.
TABLE 1
It can be seen from the comprehensive analysis examples 4-15 that the invention can refine and purify the high-content chlorothalonil product with the chlorothalonil content of more than 90%, so as to obtain the refined chlorothalonil product with higher chlorothalonil content and lower hexachlorobenzene content, and the refined chlorothalonil product meets the national standard of GB/T9551-2017 for the chlorothalonil product. In comparative example 1, when the purified raw material originally disclosed in CN108329235a (a chlorothalonil product containing 95.2% of chlorothalonil) was replaced with a high-content chlorothalonil product containing 90.1% of chlorothalonil, the content of chlorothalonil in the obtained refined chlorothalonil product could not reach the national standard, and the content of hexachlorobenzene therein was also higher than the data provided in the examples, so it can be considered that the refining problem of the high-content chlorothalonil product with a slightly lower content of chlorothalonil could not be effectively solved by the process provided in the comparative example. Meanwhile, the double-tower continuous rectification and purification process is adopted in the comparative example 1, two groups of rectifying towers are used, and only one group of rectifying tower is adopted in the invention, so that the invention has more obvious economic advantages from the perspective of production cost; from the aspect of industrialization, the batch distillation adopted by the invention has larger operation flexibility, wider range of chlorothalonil content in the processable chlorothalonil crude product, stronger applicability and more stable product quality than that of a product prepared by a proportion.
The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention disclosed herein fall within the scope and disclosure of the present invention.
Claims (33)
1. The refining and purifying device for high-content chlorothalonil is characterized by comprising a feeding unit, a rectifying unit, a condensing unit and a trapping unit which are connected in sequence;
the rectifying unit comprises a first rectifying kettle, a second rectifying kettle and a rectifying tower; the top discharge ports of the first rectifying still and the second rectifying still are connected with the lower feed port of the rectifying tower, the upper return ports of the first rectifying still and the second rectifying still are connected with the bottom return port of the rectifying tower, and the upper feed ports of the first rectifying still and the second rectifying still are connected with the discharge port of the feeding unit;
the condensation unit comprises a condensation device and a product receiving kettle which are communicated up and down, a top air inlet of the condensation device is connected with top air outlets of the first rectifying kettle and the second rectifying kettle, and a discharge hole for connecting a slicing machine is formed in the bottom of the product receiving kettle;
the refining and purifying device also comprises a vacuumizing device connected with the trapping unit;
the collecting unit comprises a first collecting device and a second collecting device, a first feeding hole, a second feeding hole and an air extracting hole are formed in the tops of the first collecting device and the second collecting device, the first feeding hole is connected with a discharging hole in the upper portion of the product receiving kettle, the second feeding hole is connected with a top extracting hole of the rectifying tower, and the air extracting hole is connected with the vacuumizing device.
2. The refining and purifying apparatus of claim 1, wherein the feeding unit includes a silo, a conveying device and a melting device connected in series.
3. The refining apparatus of claim 2, wherein the conveyor is a screw conveyor.
4. The purification apparatus of claim 3, wherein the cavities of the first and second trapping devices are single-layer or double-layer jacket structures.
5. The purification apparatus of claim 4, wherein the double-layered jacket is filled with water or air.
6. A method for refining and purifying high-content chlorothalonil, which is carried out in the refining and purifying device of any one of claims 1 to 5, and comprises the following steps:
after being melted, the crude chlorothalonil product is sent into a rectification unit for rectification, low-boiling impurities are evaporated from the top of a rectification tower and desublimated, gaseous chlorothalonil is evaporated from a rectification kettle and is sliced after condensation to obtain refined chlorothalonil;
the chlorothalonil crude product comprises chlorothalonil and hexachlorobenzene, wherein the content of the chlorothalonil is 90-99.5%, and the content of the hexachlorobenzene is 10-100ppm.
7. The purification method as claimed in claim 6, wherein the low-boiling impurities are one or a combination of two or more of hexachlorobenzene, monochlorodiphthalonitrile, dichloroisophthalonitrile, trichloroisophthalonitrile and pentachlorobenzonitrile.
8. The method of claim 6, wherein said melting is performed in a melting tank.
9. The refining and purifying method of claim 8, wherein the melting kettle is heated with heat transfer oil.
10. The refining and purifying method of claim 9, wherein the temperature of the thermal oil is 260-350 ℃.
11. The refining and purifying method of claim 10, wherein the temperature of the thermal oil is 300-330 ℃.
12. The purification process of claim 6, wherein the rectification is at an elevated temperature.
13. The refining and purifying method of claim 12, wherein the rectification unit is heated using a thermal oil.
14. The refining and purification method of claim 13, wherein the temperature of the thermally conductive oil is 260-350 ℃.
15. The refining and purification method of claim 14, wherein the temperature of the thermally conductive oil is 300-330 ℃.
16. The purification method according to claim 6, wherein the rectification is performed alternately in the first rectifying still and the second rectifying still.
17. The refining and purifying method of claim 16, wherein the rectifying tower is divided into an upper section and a lower section for heating, the lower section is heated at 300-350 ℃ and the upper section is heated at 260-330 ℃.
18. The refining and purifying method of claim 17, wherein the lower heating temperature is 320-330 ℃; the temperature of the upper section is 280-300 ℃.
19. The refining and purifying method as claimed in claim 6, wherein the temperature of the condenser at the top of the rectifying tower is 260-330 ℃.
20. The refining and purifying method as claimed in claim 19, wherein the temperature of the condenser at the top of the rectifying tower is 280-300 ℃.
21. The purification process of claim 6, wherein the distillation is carried out at a negative pressure.
22. The purification method as recited in claim 21, wherein the degree of vacuum of said distillation unit is 0.085 to 0.098MPa.
23. The refining and purifying method of claim 22, wherein the degree of vacuum of the rectifying unit is 0.09-0.095MPa.
24. The refining purification method according to claim 6, wherein the desublimation is performed in a capture unit.
25. The purification process of claim 24, wherein the desublimation is performed alternately in the first capture device and the second capture device.
26. The purification process of claim 25, wherein the first and second capture devices are each at a temperature of 30-100 ℃.
27. The method of claim 6, wherein the chlorothalonil is condensed into a product receiving tank.
28. The refining and purifying method of claim 27, wherein the condensed condensing medium is heat transfer oil, and the temperature of the heat transfer oil is 260-300 ℃.
29. The refining and purifying method of claim 28, wherein the condensed condensing medium is heat transfer oil, and the temperature of the heat transfer oil is 260-270 ℃.
30. The refining purification method of claim 27, wherein the product receiving vessel is heated using a heat transfer oil, and the temperature of the heat transfer oil is 260-300 ℃.
31. The refining purification method of claim 30, wherein the product receiving vessel is heated using a heat transfer oil, and the temperature of the heat transfer oil is 260-270 ℃.
32. The method as claimed in claim 6, wherein the content of chlorothalonil is greater than or equal to 99%.
33. The refining and purifying method as claimed in claim 6, wherein the hexachlorobenzene content in the refined chlorothalonil is less than or equal to 5ppm.
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| CN112812039B (en) * | 2021-02-07 | 2024-02-02 | 江苏新河农用化工有限公司 | Chlorothalonil lattice transformation device and method |
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