CN109438284B - Continuous rectification purification process for low-content chlorothalonil - Google Patents
Continuous rectification purification process for low-content chlorothalonil Download PDFInfo
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Abstract
The invention provides a continuous rectification and purification process of low-content chlorothalonil, which comprises the following steps: continuously rectifying a low-content chlorothalonil product with the chlorothalonil content of 65-80%, evaporating the obtained crude chlorothalonil product out of a refining kettle, and condensing to obtain refined chlorothalonil with the chlorothalonil content of more than or equal to 97%. The invention adopts continuous rectification technology combined with refining kettle for refining and purification, recovers most of chlorothalonil in low-content chlorothalonil products, and removes dangerous wastes such as hexachlorobenzene, terephthalonitrile and the like in the low-content chlorothalonil products. The obtained refined chlorothalonil product has chlorothalonil content of over 97 percent and hexachlorobenzene content of less than 10ppm which are far higher than the national standard, and meanwhile, the yield of the chlorothalonil product exceeds 80 percent, so that the threat of hazardous waste to the environment is reduced, and meanwhile, huge economic value is generated.
Description
Technical Field
The invention belongs to the field of pesticide production, relates to a purification process of chlorothalonil, particularly relates to a rectification purification process of low-content chlorothalonil, and particularly relates to a continuous rectification purification process of low-content chlorothalonil.
Background
Chlorothalonil is a high-efficiency, low-toxicity, broad-spectrum and low-residue protective bactericide, is widely applied to the prevention and control of fungal diseases in agriculture and forestry, and is very widely applied to economic crops such as vegetables, fruits and the like. According to the Japanese data, chlorothalonil has been reported to produce control effect on fifty-two diseases of over 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. With the continuous expansion of the domestic production scale of chlorothalonil, chlorothalonil has become one of large-tonnage excellent pesticide varieties in the world, and the sales condition in the international market is in a hot sales situation all the time. Chlorothalonil is defined as white powder in the national standard GB/T9551-once 2017 of China, the contents of two main indexes are more than or equal to 97 percent, and the content of hexachlorobenzene is less than or equal to 40ppm, so that the chlorothalonil is a qualified product. In the actual production, a certain amount of chlorothalonil with the content of 50-80 percent, high hexachlorobenzene content and yellow or green color is generated. The part of chlorothalonil is purified by using a traditional refining method and can not reach the indexes of qualified products, so that the chlorothalonil can only be used as solid waste for treatment, and if the unqualified chlorothalonil products are purified and refined to obtain qualified products meeting the national standard, the sales volume and sales volume of the products are greatly improved, the enterprise profits are increased, and the environmental protection pressure is relieved.
CN108329235A discloses a process method 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 not more than 0.01% and heavy components at the bottom of the light component removal tower, feeding the mixture into a product tower, and collecting chlorothalonil products with the mass fraction of not less than 99.5% from the top of the product tower. The mass fraction of the chlorothalonil product obtained by the process is more than 99.5 percent. However, the fluctuation range of the content of the chlorothalonil purified by the method cannot be overlarge, and the content cannot be too low, otherwise, the product quality is easy to be unstable.
Therefore, a more effective purification process with higher purification efficiency is urgently needed to purify chlorothalonil products with lower chlorothalonil content, and the chlorothalonil products with lower chlorothalonil content are refined to obtain qualified products, so that the product sales is greatly improved, and the enterprise profits are increased.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a continuous rectification and purification process of low-content chlorothalonil, which is used for refining a low-content chlorothalonil product on the basis of the traditional continuous rectification and purification process, and can refine and purify a chlorothalonil product with lower chlorothalonil content and higher hexachlorobenzene content to obtain a refined chlorothalonil product with chlorothalonil content of more than or equal to 97 percent and hexachlorobenzene content of less than or equal to 10ppm, so that hazardous wastes in the low-content chlorothalonil product are effectively removed, the harm of the hexachlorobenzene to soil and environment is reduced, meanwhile, huge economic benefits are generated, and the production cost is saved.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present embodiment provides a continuous rectification and purification process of low-content chlorothalonil, including:
continuously rectifying a low-content chlorothalonil product with the chlorothalonil content of 65-80%, evaporating an obtained crude product of the chlorothalonil product from a refining kettle, and condensing to obtain a refined chlorothalonil product with the chlorothalonil content of more than or equal to 97%.
As a preferable technical scheme of the invention, the process comprises the following steps:
feeding a low-content chlorothalonil product containing 65-80% of chlorothalonil from the middle of a first rectifying tower through a feeding unit;
(II) extracting light components in the product from the top of the first rectifying tower, and allowing the light components to enter a first front fraction trapping device for desublimation, wherein heavy components are fed from the middle of a second rectifying tower of the rectifying unit;
(III) extracting low-boiling-point substances in the heavy components obtained in the step (II) from the top of the second rectifying tower, allowing the low-boiling-point substances to enter a second front fraction trapping device for desublimation, and extracting crude chlorothalonil from the bottom of the second rectifying tower;
and (IV) introducing the crude chlorothalonil obtained in the step (III) into a refining kettle, steaming out a refined chlorothalonil product, condensing, and collecting to a product receiving kettle to obtain a refined chlorothalonil product.
The low-content chlorothalonil product comprises chlorothalonil and hexachlorobenzene, wherein the content of the chlorothalonil is 65-80%, and can be 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79% or 80%, for example; the hexachlorobenzene content is 100-3000ppm, and may be, for example, 200ppm, 400ppm, 600ppm, 800ppm, 1000ppm, 1200ppm, 1400ppm, 1600ppm, 1800ppm, 2000ppm, 2200ppm, 2400ppm, 2600ppm or 2800 ppm.
The invention refines the chlorothalonil product again on the basis of the traditional continuous rectification purification process, and realizes the refining and purification of the chlorothalonil product with lower content of the chlorothalonil. After the low-content chlorothalonil product is rectified by the first rectifying tower, most of low-boiling-point dangerous waste such as hexachlorobenzene and the like in the chlorothalonil product is removed, the residual hexachlorobenzene in the other components is removed after the rectification by the second rectifying tower, finally, crude chlorothalonil containing heavy component dangerous waste such as tetrachloroterephthalonitrile and the like is fed into a refining kettle for refining, the refined chlorothalonil is distilled out from the refining kettle, the heavy component dangerous waste is left in the refining kettle, slag is discharged and bagged for treatment or recovery, and the distilled refined chlorothalonil is condensed and collected to obtain a solid refined chlorothalonil product, so that the low-content chlorothalonil purification process can be adopted to refine and purify the chlorothalonil product with higher hexachlorobenzene content and lower chlorothalonil content to obtain the refined chlorothalonil product with the chlorothalonil content of more than or equal to 97 percent and the hexachlorobenzene content of less than or equal to 10ppm, thereby effectively removing the danger in the low-content chlorothalonil product, the harm of hexachlorobenzene to soil and environment is reduced, and meanwhile, huge economic benefits are generated, and the production cost is saved.
As a preferred technical scheme of the invention, according to the sequence of the process flow, the low-content chlorothalonil product in the step (I) is introduced into the first rectifying tower through the melting kettle, the melting intermediate tank and the feeding superheating device of the feeding unit in sequence.
Preferably, the melting kettle, the melting intermediate tank and the feeding overheating device are heated by adopting heat conducting oil.
Preferably, the temperature of the heat conducting oil is 260-.
Preferably, the feed is a bubble point feed.
Preferably, step (i) further comprises desublimating the partially vaporized product in the melting vessel via a melt trap device for recycling to the melting vessel.
Preferably, a jacket is arranged outside the cavity of the melting and trapping device.
Preferably, water or cold air is introduced into the jacket.
Preferably, the temperature in the melting and trapping device is controlled to 40 to 150 ℃, for example, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃ or 150 ℃, preferably 60 to 80 ℃.
As a preferred technical scheme of the invention, the first distillation column in the step (I) and the step (II) is divided into an upper section and a lower section for heating, wherein the upper section is heated at the temperature of 260-; the lower heating temperature is 300-350 ℃, for example, 300 ℃, 305 ℃, 310 ℃, 315 ℃, 320 ℃, 325 ℃, 330 ℃, 335 ℃, 340 ℃, 345 ℃ or 350 ℃, preferably 320-330 ℃.
Preferably, the degree of vacuum of the top front end of the first rectifying tower is 0.05 to 0.095MPa, and may be, for example, 0.05MPa, 0.10MPa, 0.15MPa, 0.20MPa, 0.25MPa, 0.30MPa, 0.35MPa, 0.40MPa, 0.45MPa, 0.50MPa, 0.55MPa, 0.60MPa, 0.65MPa, 0.70MPa, 0.75MPa, 0.80MPa, 0.85MPa, 0.90MPa or 0.95MPa, preferably 0.06 to 0.07 MPa.
Preferably, the top of the first distillation column is provided with a first condensing device, and the temperature of the first condensing device is 250-330 ℃, for example, 250 ℃, 260 ℃, 270 ℃, 280 ℃, 290 ℃, 300 ℃, 310 ℃, 320 ℃ or 330 ℃, preferably 260-290 ℃.
Preferably, the bottom of the first distillation column is provided with a first reboiling device, and the temperature of the first reboiling device is 300-350 ℃, for example, 300 ℃, 305 ℃, 310 ℃, 315 ℃, 320 ℃, 325 ℃, 330 ℃, 335 ℃, 340 ℃, 345 ℃ or 350 ℃, preferably 310-330 ℃.
As a preferable technical scheme of the invention, the light component in the step (II) contains hexachlorobenzene.
Preferably, the cavity of the first front fraction collecting device is provided with a jacket outside.
Preferably, water or cold air is introduced into the jacket.
Preferably, the temperature in the first front cut collecting device is controlled to 40 to 150 ℃, for example, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃ or 150 ℃, preferably 60 to 80 ℃.
As a preferred technical scheme of the invention, the second distillation column in the step (II) and the step (III) is divided into an upper section and a lower section for heating, wherein the upper section is heated at the temperature of 260-; the lower heating temperature is 300-350 ℃, for example, 300 ℃, 305 ℃, 310 ℃, 315 ℃, 320 ℃, 325 ℃, 330 ℃, 335 ℃, 340 ℃, 345 ℃ or 350 ℃, preferably 320-330 ℃.
Preferably, the vacuum degree of the top front cut of the second rectifying tower is 0.05-0.095MPa, such as 0.05MPa, 0.055MPa, 0.06MPa, 0.065MPa, 0.07MPa, 0.075MPa, 0.08MPa, 0.085MPa, 0.09MPa or 0.095MPa, preferably 0.06-0.08 MPa.
Preferably, the top of the second distillation column is provided with a second condensing device, and the temperature of the second condensing device is 250-330 ℃, for example, 250 ℃, 260 ℃, 270 ℃, 280 ℃, 290 ℃, 300 ℃, 310 ℃, 320 ℃ or 330 ℃, preferably 260-290 ℃.
Preferably, the bottom of the second distillation column is provided with a second reboiling device, and the temperature of the second reboiling device is 350 ℃, for example, 300 ℃, 305 ℃, 310 ℃, 315 ℃, 320 ℃, 325 ℃, 330 ℃, 335 ℃, 340 ℃, 345 ℃ or 350 ℃, preferably 310 ℃ and 330 ℃.
As a preferred embodiment of the present invention, the low boiling substance in the step (III) contains hexachlorobenzene.
Preferably, the cavity of the second front fraction collecting device is provided with a jacket outside.
Preferably, water or cold air is introduced into the jacket.
Preferably, the temperature in the second front cut collecting device is controlled to 40 to 150 ℃, for example, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃ or 150 ℃, preferably 60 to 80 ℃.
As a preferred embodiment of the present invention, the degree of vacuum in the purification vessel in the step (IV) is 0.05 to 0.095MPa, and may be, for example, 0.05MPa, 0.055MPa, 0.06MPa, 0.065MPa, 0.07MPa, 0.075MPa, 0.08MPa, 0.085MPa, 0.09MPa or 0.095MPa, preferably 0.07 to 0.09 MPa.
Preferably, the refining kettle is heated by adopting heat conduction oil.
Preferably, the temperature of the heat conducting oil is 260-.
Preferably, the condensation is carried out in a condensation device.
Preferably, the condensing medium of the condensing device is heat conducting oil.
Preferably, the temperature of the condensing medium is 240-330 ℃, for example, 240 ℃, 250 ℃, 260 ℃, 270 ℃, 280 ℃, 290 ℃, 300 ℃, 310 ℃, 320 ℃ or 330 ℃, preferably 250-280 ℃.
Preferably, the product receiving kettle is heated by adopting heat conducting oil.
Preferably, the temperature of the heat conducting oil is 240-330 ℃, for example, 240 ℃, 250 ℃, 260 ℃, 270 ℃, 280 ℃, 290 ℃, 300 ℃, 310 ℃, 320 ℃ or 330 ℃, preferably 250-280 ℃.
As a preferred technical scheme of the invention, the step (IV) further comprises the following steps: and (3) desublimating the incompletely condensed chlorothalonil product in a product catching device arranged in the subsequent process flow of the product receiving kettle.
Preferably, the product trapping device is heated by using heat conducting oil.
Preferably, a jacket is arranged outside the cavity of the product trapping device.
Preferably, water or cold air is introduced into the jacket.
Preferably, the temperature of the trapping device is controlled at 40-150 deg.C, such as 40 deg.C, 50 deg.C, 60 deg.C, 70 deg.C, 80 deg.C, 90 deg.C, 100 deg.C, 110 deg.C, 120 deg.C, 130 deg.C, 140 deg.C or 150 deg.C, preferably 60-80 deg.C.
In a second aspect, the present invention provides a refined chlorothalonil, prepared by a process as described in the first aspect.
Preferably, the refined chlorothalonil comprises chlorothalonil and hexachlorobenzene; wherein the content of chlorothalonil is more than or equal to 97 percent, and can be 97 percent, 97.5 percent, 98 percent, 98.5 percent, 99 percent or 99.5 percent, for example; the hexachlorobenzene content is less than or equal to 10%, and may be, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%.
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 beneficial effects that:
the invention adopts continuous rectification technology combined with refining kettle for refining and purification, recovers most of chlorothalonil in low-content chlorothalonil products, and removes dangerous wastes such as hexachlorobenzene, terephthalonitrile and the like in the low-content chlorothalonil products. The obtained refined chlorothalonil product has chlorothalonil content of over 97 percent and hexachlorobenzene content of less than 10ppm which are far higher than the national standard, and meanwhile, the yield of the chlorothalonil product exceeds 80 percent, so that the threat of hazardous waste to the environment is reduced, and meanwhile, huge economic value is generated.
Drawings
FIG. 1 is a flow chart of a continuous distillation and purification system for low-content chlorothalonil, which is provided by the embodiment 1 of the invention.
Wherein, 1-a crude product bin; 2-a feed screw conveyor; 3-melting kettle; 4-a pipeline filter; 5-a metering pump; 6-melting the intermediate tank; 7-rectifying tower feeding superheater; 8-a first rectification column; 9-a second rectification column; 10-refining kettle; 11-product condenser; 12-a product receiving kettle; 13-melting the catcher; 14-a first front end trap; 15-a second front end trap; 16-a first product trap; 17-a second product trap; 18-a first forecut vacuum pump; 19-a second forecut vacuum pump; 20-product vacuum pump.
Detailed Description
The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.
In one embodiment, the invention provides a continuous rectification and purification process of low-content chlorothalonil, which specifically comprises the following steps:
(1) a certain amount of low-content chlorothalonil product is continuously conveyed into a melting kettle 3 through a crude product bin 1 and a feeding screw conveyor 2.
(2) The low-content chlorothalonil product is melted into liquid chlorothalonil in the melting kettle 3, impurities are filtered out through the pipeline filter 4, then the liquid chlorothalonil is conveyed into the melting intermediate tank 6 through the metering pump 5, and the liquid chlorothalonil is heated to the bubble point temperature through the rectifying tower feeding superheater 7 and then fed from the middle of the first rectifying tower 8.
(3) The liquid chlorothalonil enters the first rectifying tower 8 for rectification operation, and a part of light components with very high hexachlorobenzene content are extracted from the top of the first rectifying tower 8 and enter the first front fraction catcher 14 for desublimation into solids. The rest components are extracted from the bottom of the first rectifying tower 8 and fed from the middle of the second rectifying tower 9.
(4) And (4) continuously rectifying the rest components in the step (3) in a second rectifying tower 9, wherein a part of low-boiling-point substances with higher hexachlorobenzene content are extracted from the top of the second rectifying tower 9 and enter a second front fraction catcher 15 to be desublimated into a solid.
(5) And the crude chlorothalonil extracted from the bottom of the second rectifying tower 9 flows into a refining kettle 10, the refined chlorothalonil is evaporated, is condensed by a product condenser 11 and then is collected into a product receiving kettle 12 to obtain solid refined chlorothalonil, and the solid refined chlorothalonil is sliced and packaged by a slicer.
(6) The gaseous chlorothalonil which is not completely condensed is desublimated in the first product catcher 16 and the second product catcher 17, if the chlorothalonil in the first product catcher 16 and the second product catcher 17 is qualified, the chlorothalonil can be directly bagged and packaged, and if the chlorothalonil is unqualified, the chlorothalonil can be recovered and then is subjected to centralized treatment.
Example 1
The embodiment provides a continuous rectification and purification system for low-content chlorothalonil, which comprises a feeding unit, a continuous rectification unit and a refining unit which are connected in sequence, as shown in figure 1.
The feeding unit comprises a crude product bin 1, a feeding screw conveyor 2, a melting kettle 3, a pipeline filter 4, a metering pump 5, a melting intermediate tank 6 and a rectifying tower feeding superheater 7 which are connected in sequence; the feeding unit further comprises a melting catcher 13, wherein a top inlet of the melting catcher 13 is connected with a top outlet of the melting middle tank 6, and a top outlet of the melting catcher 13 is connected with a top feed back port of the melting kettle 3.
The cavity materials of the crude product bin 1 and the feeding screw conveyor 2 are selected from 304 stainless steel.
The melting kettle 3 comprises a melting kettle cavity and a jacket arranged outside the melting kettle cavity; wherein the melting kettle cavity is made of hastelloy; the heat conducting oil is introduced into the jacket, and the melting kettle 3 further comprises an inner coil pipe positioned at the bottom of the melting kettle cavity and a stirring component positioned inside the melting kettle cavity.
The metering pump 5 is a plunger type metering pump.
The cavity materials of the pipeline filter 4 and the metering pump 5 are hastelloy.
The melting intermediate tank 6 comprises a melting intermediate tank cavity and a jacket arranged outside the melting intermediate tank cavity; wherein, the contact part of the melting intermediate tank 6 and the liquid material is made of lining nickel material, and the rest is carbon steel; heat conducting oil is introduced into the jacket.
The rectifying tower feeding superheater 7 is a tube type heat exchanger, the tube side of the rectifying tower feeding superheater 7 is hastelloy, and the shell side is carbon steel.
The melting catcher 13 comprises a melting catcher cavity and a jacket arranged outside the melting catcher cavity; the melting catcher cavity is made of 304 stainless steel, a baffle is arranged inside the melting catcher cavity, circulating water is introduced into the jacket, and a filter screen is arranged at a gas phase outlet of the melting catcher 13.
The continuous rectification unit comprises a first rectification tower 8 and a second rectification tower 9 which are sequentially connected, and a discharge hole at the bottom of the first rectification tower 8 is connected with a feed inlet at the middle section of the second rectification tower 9; filling materials are filled in the cavities of the first rectifying tower 8 and the second rectifying tower 9, the filling materials are Monel 400, and the rest materials are Hastelloy; the tower is also provided with a tower plate, the outer side of the tower is provided with a heat tracing pipe, the top of the first rectifying tower 8 and the second rectifying tower 9 is provided with a tubular condenser, and the bottom of the tower is provided with a tubular reboiler.
The continuous rectification unit also comprises a first front cut trap 14 connected to the top outlet of the first rectification column 8 and a second front cut trap 15 connected to the top outlet of the second rectification column 9.
The material of the chamber of the first front cut catcher 14 and the second front cut catcher 15 is selected from 304 stainless steel. The first front fraction catcher 14 and the second front fraction catcher 15 are provided with baffles inside the cavity, and jacket is arranged on the outside, and circulating water is introduced into the jacket. And filter screens are arranged at the gas phase outlets of the first front fraction catcher 14 and the second front fraction catcher 15.
The refining unit comprises a refining kettle 10, a product condenser 11 and a product receiving kettle 12 which are connected in sequence; the top feed inlet of the refining kettle 10 is connected with the bottom discharge hole of the second rectifying tower 9, the bottom of the refining kettle 10 is provided with a slag discharge hole, and the bottom of the product receiving kettle 12 is provided with a discharge hole for connecting a slicing machine.
The material of the cavity of the refining kettle 10 is corrosion resistant alloy, a stirring component is arranged in the cavity, an inner coil pipe is arranged at the bottom of the cavity, a jacket is arranged outside the cavity, and heat conducting oil is introduced into the jacket.
The product condenser 11 is a shell-and-tube heat exchanger, the tube side of the product condenser 11 is hastelloy, the shell side is carbon steel, and the cavity of the product receiving kettle 12 is made of corrosion-resistant alloy.
The system further comprises a first product trap 16 and a second product trap 17 connected in series with the outlet of the refining unit.
The first product catcher 16 and the second product catcher 17 are made of a material selected from 304 stainless steel. The first product catcher 16 and the second product catcher 17 are provided with baffle plates inside, jacket is arranged on the outer side, and circulating water is introduced into the jacket. The gas phase outlets of the first product catcher 16 and the second product catcher 17 are both provided with filter screens.
The system further comprises a first front end vacuum pump 18, a second front end vacuum pump 19 and a product vacuum pump 20; an inlet of a first front cut vacuum pump 18 is connected with a top outlet of the first front cut trap 14, an inlet of a second front cut vacuum pump 19 is connected with a top outlet of the second front cut trap 15, and a product vacuum pump 20 is connected with a top outlet of the second product trap 17.
The first front-end vacuum pump 18, the second front-end vacuum pump 19 and the product vacuum pump 20 are selected from water-ring vacuum pumps.
Example 2
The embodiment provides a continuous rectification and purification process for low-content chlorothalonil, which is performed in the purification system provided in embodiment 1, and specifically comprises the following steps:
(1) 3 tons of low-content chlorothalonil products continuously enter a melting kettle 3 through a crude product bin 1 and a feeding screw conveyor 2, the oil temperature of heat conducting oil in a jacket of the melting kettle 3 is 330 ℃, and the chlorothalonil products contain 65.9 percent of chlorothalonil and 2850ppm of hexachlorobenzene.
(2) The low-content chlorothalonil product is continuously melted into a liquid chlorothalonil product in the melting kettle 3, impurities in the liquid chlorothalonil product are filtered out through a pipeline filter 4 and then continuously introduced into a melting intermediate tank 6 through a metering pump 5, the liquid chlorothalonil product is heated to a bubble point temperature through a rectifying tower feeding superheater 7 and then continuously enters a tower from the middle of a first rectifying tower 8, and the oil temperature of heat conducting oil in jackets of the melting intermediate tank 6 and the rectifying tower feeding superheater 7 is 330 ℃. The partially evaporated chlorothalonil product in the melting kettle 3 enters the melting catcher 13 through the melting intermediate tank 6, is condensed into solid and then is recycled to the melting kettle 3 for continuous melting, and the outlet temperature of the melting catcher 13 is 60 ℃.
(3) The liquid chlorothalonil product enters a first rectifying tower 8 for rectification operation, wherein light components are extracted from the top of the first rectifying tower 8 and enter a first front fraction catcher 14 for desublimation to form solids, the solids are bagged and then subjected to solid waste treatment, the rest heavy components are extracted from the bottom of the first rectifying tower 8 and are fed from the middle of a second rectifying tower 9, the temperature of the upper section of the first rectifying tower 8 is 280 ℃, the temperature of the lower section of the first rectifying tower 8 is 330 ℃, the outlet temperature of an overhead condenser is 260 ℃, the temperature of a tower bottom reboiler is 330 ℃, the vacuum degree of the front fraction at the top of the tower is 0.07MPa, and the outlet temperature of the first front fraction catcher 14 is 60 ℃.
(4) And (4) continuously performing rectification operation on heavy components fed from the middle of the second rectifying tower 9 in the step (3) in the second rectifying tower 9, wherein low-boiling-point substances are extracted from the top of the second rectifying tower 9 and enter a second front fraction catcher 15 to be desublimated into solid, and after being bagged, performing solid waste treatment, wherein crude chlorothalonil is extracted from the bottom of the second rectifying tower 9. The upper section temperature of the second rectifying tower 9 is 280 ℃, the lower section temperature is 330 ℃, the outlet temperature of the overhead condenser is 260 ℃, the temperature of the tower bottom reboiler is 330 ℃, the vacuum degree of the overhead front cut fraction is 0.08MPa, and the outlet temperature of the second front cut fraction catcher 15 is 60 ℃.
(5) And introducing the crude chlorothalonil extracted from the bottom of the second rectifying tower 9 into a refining kettle 10, distilling out the refined chlorothalonil, condensing by a product condenser 11, collecting into a product receiving kettle 12 to obtain solid refined chlorothalonil, and slicing and packaging by a slicer. The temperature of heat conducting oil in a jacket of the refining kettle 10 is 330 ℃, the vacuum degree in the refining kettle 10 is 0.08MPa, and the product condenser 11 and the product receiving kettle 12 are heated by adopting heat conducting oil, and the temperature of the heat conducting oil is 260 ℃.
(6) The gaseous chlorothalonil which is not completely condensed is desublimated in the first product catcher 16 and the second product catcher 17, if the chlorothalonil in the first product catcher 16 and the second product catcher 17 is qualified, the chlorothalonil can be directly bagged and packaged, and if the chlorothalonil is unqualified, the chlorothalonil can be recovered and then is subjected to centralized treatment. The outlet temperature of the first product trap 16 and the second product trap 17 is 60 ℃.
The data of the chlorothalonil content and the hexachlorobenzene content, the rectification yield, the percentage of the solid waste amount to the rectification raw material amount and the like in the refined chlorothalonil prepared in the embodiment are shown in table 1.
Example 3
The difference from the example 2 is that the vacuum degree of the front fraction of the first rectifying tower is changed to 0.055MPa, and other technological operation parameters are the same as the example 2.
The summary data of the chlorothalonil content and the hexachlorobenzene content, the rectification yield, the percentage of the solid waste amount to the rectification raw material amount and the like in the refined chlorothalonil prepared in the embodiment are shown in table 1.
Example 4
The difference from the example 2 is that the front fraction vacuum degree of the first rectifying tower is changed to 0.06MPa, and other process operating parameters are the same as the example 2.
The summary data of the chlorothalonil content and the hexachlorobenzene content, the rectification yield, the percentage of the solid waste amount to the rectification raw material amount and the like in the refined chlorothalonil prepared in the embodiment are shown in table 1.
Example 5
The difference from the example 2 is that the front fraction vacuum degree of the first rectifying tower is changed to 0.08MPa, and other process operating parameters are the same as the example 2.
The summary data of the chlorothalonil content and the hexachlorobenzene content, the rectification yield, the percentage of the solid waste amount to the rectification raw material amount and the like in the refined chlorothalonil prepared in the embodiment are shown in table 1.
Example 6
The difference from the example 2 is that the vacuum degree of the front cut of the first rectifying tower is changed to 0.095MPa, and other technological operating parameters are the same as those of the example 2.
The summary data of the chlorothalonil content and the hexachlorobenzene content, the rectification yield, the percentage of the solid waste amount to the rectification raw material amount and the like in the refined chlorothalonil prepared in the embodiment are shown in table 1.
Example 7
The difference from the example 2 is that the chlorothalonil content in the low-content chlorothalonil product is 72.5 percent, the hexachlorobenzene content is 1350ppm, the vacuum degree of the distillate at the front part of the second rectifying tower is changed to 0.05MPa, and other technological operating parameters are the same as those in the example 2.
The summary data of the chlorothalonil content and the hexachlorobenzene content, the rectification yield, the percentage of the solid waste amount to the rectification raw material amount and the like in the refined chlorothalonil prepared in the embodiment are shown in table 1.
Example 8
The difference from the example 2 is that the chlorothalonil content in the low-content chlorothalonil product is 72.5 percent, the hexachlorobenzene content is 1350ppm, the vacuum degree of the distillate at the front part of the second rectifying tower is changed to 0.06MPa, and other technological operating parameters are the same as those in the example 2.
The summary data of the chlorothalonil content and the hexachlorobenzene content, the rectification yield, the percentage of the solid waste amount to the rectification raw material amount and the like in the refined chlorothalonil prepared in the embodiment are shown in table 1.
Example 9
The difference from the example 2 is that the chlorothalonil content in the low-content chlorothalonil product is 72.5 percent, the hexachlorobenzene content is 1350ppm, the vacuum degree of the distillate at the front part of the second rectifying tower is changed to 0.08MPa, and other technological operating parameters are the same as those in the example 2.
The summary data of the chlorothalonil content and the hexachlorobenzene content, the rectification yield, the percentage of the solid waste amount to the rectification raw material amount and the like in the refined chlorothalonil prepared in the embodiment are shown in table 1.
Example 10
The difference from the example 2 is that the chlorothalonil content in the low-content chlorothalonil product is 72.5 percent, the hexachlorobenzene content is 1350ppm, the vacuum degree of the distillate at the front part of the second rectifying tower is changed to 0.09MPa, and other technological operating parameters are the same as those in the example 2.
The summary data of the chlorothalonil content and the hexachlorobenzene content, the rectification yield, the percentage of the solid waste amount to the rectification raw material amount and the like in the refined chlorothalonil prepared in the embodiment are shown in table 1.
Example 11
The difference from the example 2 is that the chlorothalonil content in the low-content chlorothalonil product is 73.8 percent, the hexachlorobenzene content is 560ppm, the temperature of the condenser at the top of the first rectifying tower 8 and the second rectifying tower 9 is changed to 250 ℃, the temperature of the upper section of the tower body is changed to 260 ℃, the temperature of the lower section of the tower body is changed to 300 ℃, the temperature of the reboiler at the bottom of the tower body is 310 ℃, and other technological operating parameters are the same as those in the example 2.
The summary data of the chlorothalonil content and the hexachlorobenzene content, the rectification yield, the percentage of the solid waste amount to the rectification raw material amount and the like in the refined chlorothalonil prepared in the embodiment are shown in table 1.
Example 12
The difference from the example 2 is that the chlorothalonil content in the low-content chlorothalonil product is 73.8 percent, the hexachlorobenzene content is 560ppm, the temperature of the condenser at the top of the first rectifying tower 8 and the second rectifying tower 9 is changed to 260 ℃, the temperature of the upper section of the tower body is changed to 280 ℃, the temperature of the lower section of the tower body is changed to 310 ℃, the temperature of the reboiler at the bottom of the tower body is 320 ℃, and other technological operating parameters are the same as those in the example 2.
The summary data of the chlorothalonil content and the hexachlorobenzene content, the rectification yield, the percentage of the solid waste amount to the rectification raw material amount and the like in the refined chlorothalonil prepared in the embodiment are shown in table 1.
Example 13
The difference from the example 2 is that the chlorothalonil content in the low-content chlorothalonil product is 73.8 percent, the hexachlorobenzene content is 560ppm, the temperature of the condenser at the top of the first rectifying tower 8 and the second rectifying tower 9 is changed to 290 ℃, the temperature of the upper section of the tower body is changed to 300 ℃, the temperature of the lower section of the tower body is changed to 330 ℃, the temperature of the reboiler at the bottom of the tower body is 330 ℃, and other technological operating parameters are the same as those in the example 2.
The summary data of the chlorothalonil content and the hexachlorobenzene content, the rectification yield, the percentage of the solid waste amount to the rectification raw material amount and the like in the refined chlorothalonil prepared in the embodiment are shown in table 1.
Example 14
The difference from the example 2 is that the chlorothalonil content in the low-content chlorothalonil product is 73.8 percent, the hexachlorobenzene content is 560ppm, the temperature of the condenser at the top of the first rectifying tower 8 and the second rectifying tower 9 is changed to 320 ℃, the temperature of the upper section of the tower body is changed to 330 ℃, the temperature of the lower section of the tower body is changed to 350 ℃, the temperature of the reboiler at the bottom of the tower body is 350 ℃, and other technological operating parameters are the same as those in the example 2.
The summary data of the chlorothalonil content and the hexachlorobenzene content, the rectification yield, the percentage of the solid waste amount to the rectification raw material amount and the like in the refined chlorothalonil prepared in the embodiment are shown in table 1.
Example 15
The difference from the example 2 is that the chlorothalonil content in the low-content chlorothalonil product is 67.6 percent, the hexachlorobenzene content is 2160ppm, the temperature of the heat-conducting oil in the refining kettle 10 is changed to 260 ℃, the vacuum degree in the refining kettle 10 is 0.05MPa, and other technological operating parameters are the same as those in the example 2.
The summary data of the chlorothalonil content and the hexachlorobenzene content, the rectification yield, the percentage of the solid waste amount to the rectification raw material amount and the like in the refined chlorothalonil prepared in the embodiment are shown in table 1.
Example 16
The difference from the example 2 is that the chlorothalonil content in the low-content chlorothalonil product is 67.6 percent, the hexachlorobenzene content is 2160ppm, the temperature of the heat-conducting oil in the refining kettle 10 is changed to 300 ℃, the vacuum degree in the refining kettle 10 is 0.07MPa, and other technological operating parameters are the same as those in the example 2.
The summary data of the chlorothalonil content and the hexachlorobenzene content, the rectification yield, the percentage of the solid waste amount to the rectification raw material amount and the like in the refined chlorothalonil prepared in the embodiment are shown in table 1.
Example 17
The difference from the example 2 is that the chlorothalonil content in the low-content chlorothalonil product is 67.6 percent, the hexachlorobenzene content is 2160ppm, the temperature of the heat transfer oil in the refining kettle 10 is changed to 330 ℃, the vacuum degree in the refining kettle 10 is 0.09MPa, and other technological operating parameters are the same as those in the example 2.
The summary data of the chlorothalonil content and the hexachlorobenzene content, the rectification yield, the percentage of the solid waste amount to the rectification raw material amount and the like in the refined chlorothalonil prepared in the embodiment are shown in table 1.
Example 18
The difference from the example 2 is that the chlorothalonil content in the low-content chlorothalonil product is 67.6 percent, the hexachlorobenzene content is 2160ppm, the temperature of the heat-conducting oil in the refining kettle 10 is changed to 350 ℃, the vacuum degree in the refining kettle 10 is 0.095MPa, and other technological operating parameters are the same as those in the example 2.
The summary data of the chlorothalonil content and the hexachlorobenzene content, the rectification yield, the percentage of the solid waste amount to the rectification raw material amount and the like in the refined chlorothalonil prepared in the embodiment are shown in table 1.
Example 19
The difference from the example 2 is that the chlorothalonil content in the low-content chlorothalonil product is 79.6 percent, the hexachlorobenzene content is 106ppm, the temperature of the heat transfer oil in the melting kettle 3, the melting intermediate tank 6 and the feeding superheater 7 is changed to 260 ℃, and other process operating parameters are the same as those in the example 2.
The summary data of the chlorothalonil content and the hexachlorobenzene content, the rectification yield, the percentage of the solid waste amount to the rectification raw material amount and the like in the refined chlorothalonil prepared in the embodiment are shown in table 1.
Example 20
The difference from the example 2 is that the chlorothalonil content in the low-content chlorothalonil product is 79.6 percent, the hexachlorobenzene content is 106ppm, the temperature of the heat transfer oil in the melting kettle 3, the melting intermediate tank 6 and the feeding superheater 7 is changed to 350 ℃, and other process operating parameters are the same as those in the example 2.
The summary data of the chlorothalonil content and the hexachlorobenzene content, the rectification yield, the percentage of the solid waste amount to the rectification raw material amount and the like in the refined chlorothalonil prepared in the embodiment are shown in table 1.
Comparative example 1
CN108329235A describes a process method of high purity chlorothalonil, wherein example 1 provides a process for purifying chlorothalonil, comprising: the raw material is a chlorothalonil product containing 95.2 percent of chlorothalonil, the operating pressure of a first rectifying tower is 1KPa absolute pressure, the temperature of the top of the tower is 200 ℃, and the temperature of the bottom of the tower is 345 ℃; the second distillation column was operated at an absolute pressure of 1KPa, a head temperature of 321 ℃ and a bottom temperature of 346 ℃. In the two condensing towers, the condensing medium of a condenser communicated with the top of the first rectifying tower is heat conducting oil, and the temperature of the heat conducting oil is 150 ℃; the condensing medium of the condenser communicated with the top of the second rectifying tower is heat conducting oil, and the temperature of the heat conducting oil is 260 ℃.
In the comparative example, the raw material of chlorothalonil was replaced by a chlorothalonil product containing 65.9 percent of chlorothalonil and 2850ppm of hexachlorobenzene, and other process operating parameters are the same as those in example 1 in CN 108329235A.
The summary data of the chlorothalonil content, the hexachlorobenzene content, the rectification yield, the percentage of solid waste to the rectification raw material amount and the like in the refined chlorothalonil prepared in the comparative example are shown in table 1.
TABLE 1
By comprehensively analyzing the examples 2-20 and the comparative example 1, the chlorothalonil content in the low-content chlorothalonil provided by the embodiment of the invention is 65-80%, and after purification operation, the chlorothalonil content in the obtained refined chlorothalonil product reaches more than 97%, which meets the national standard of GB/T9551-2017 for the chlorothalonil product. In contrast, in comparative example 1, the process method provided by CN108329235A is adopted, and only when the raw material is replaced with a chlorothalonil product with a lower chlorothalonil content (a chlorothalonil product containing 65.9% of chlorothalonil), the obtained refined chlorothalonil product cannot meet the national standard, so that the process method provided by the comparative example cannot be considered to effectively solve the problem of purifying a chlorothalonil product with an excessively low chlorothalonil content.
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 are within the scope and disclosure of the present invention.
Claims (43)
1. A continuous rectification purification process for low-content chlorothalonil, which is characterized by comprising the following steps:
continuously rectifying a low-content chlorothalonil product with the chlorothalonil content of 65-80%, evaporating an obtained crude product of chlorothalonil from a refining kettle, and condensing to obtain solid refined chlorothalonil with the chlorothalonil content of more than or equal to 97%;
the process comprises the following steps:
feeding a low-content chlorothalonil product from the middle of a first rectifying tower through a feeding unit; the low-content chlorothalonil product is introduced into the first rectifying tower through the melting kettle, the melting intermediate tank and the feeding overheating device of the feeding unit in sequence; heating the melting kettle, the melting intermediate tank and the feeding overheating device by adopting first heat conduction oil; the temperature of the first heat conduction oil is 260-350 ℃;
(II) extracting light components from the top of the first rectifying tower, allowing the light components to enter a first front fraction trapping device for desublimation, and feeding heavy components from the middle of a second rectifying tower of the rectifying unit; the vacuum degree of the distillate at the front part of the tower top of the first rectifying tower is 0.05-0.095 MPa; the first rectifying tower is divided into an upper section and a lower section for heating, and the heating temperature of the first upper section is 260-330 ℃; the heating temperature of the first lower section is 300-350 ℃; a first condensing device is arranged at the top of the first rectifying tower, and the temperature of the first condensing device is 250-330 ℃; the tower bottom of the first rectifying tower is provided with a first reboiling device, and the temperature of the first reboiling device is 300-350 ℃;
(III) extracting low-boiling-point substances in the heavy components obtained in the step (II) from the top of the second rectifying tower, allowing the low-boiling-point substances to enter a second front fraction trapping device for desublimation, and extracting crude chlorothalonil from the bottom of the second rectifying tower; the vacuum degree of the distillate at the front part of the tower top of the second rectifying tower is 0.05-0.095 MPa; the second rectifying tower is divided into an upper section and a lower section for heating, and the heating temperature of the second upper section is 260-330 ℃; the heating temperature of the second lower section is 300-350 ℃; a second condensing device is arranged at the top of the second rectifying tower, and the temperature of the second condensing device is 250-330 ℃; a second reboiling device is arranged at the bottom of the second rectifying tower, and the temperature of the second reboiling device is 300-350 ℃;
(IV) introducing the crude chlorothalonil obtained in the step (III) into a refining kettle, steaming out a refined chlorothalonil product, condensing, and collecting into a product receiving kettle to obtain a refined chlorothalonil product; the vacuum degree of the refining kettle is 0.05-0.095 MPa; heating the refining kettle by adopting second heat conduction oil; the temperature of the second heat conduction oil is 260-350 ℃;
the low-content chlorothalonil product comprises chlorothalonil and hexachlorobenzene, wherein the hexachlorobenzene content is 100-3000 ppm.
2. The process as claimed in claim 1, wherein the temperature of the first thermal oil is 300-330 ℃.
3. The process of claim 1, wherein the feed is a bubble point feed.
4. The process of claim 1, wherein step (i) further comprises desublimating the partially vaporized chlorothalonil product in the melting vessel via a melt trap device for recycling to the melting vessel.
5. The process of claim 4, wherein the melt trap device is provided with a first jacket outside the cavity.
6. The process according to claim 5, wherein water or cold air is introduced into the first jacket.
7. The process of claim 4 wherein the temperature within the melt trap device is controlled to be in the range of 40-150 ℃.
8. The process of claim 7 wherein the temperature within the melt trap device is controlled to be between 60 ℃ and 80 ℃.
9. The process as claimed in claim 1, wherein the first upper heating temperature is 280-300 ℃.
10. The process as claimed in claim 1, wherein the first lower heating temperature is 320-330 ℃.
11. The process of claim 1, wherein the overhead vacuum of the first rectification column is 0.06-0.07 MPa.
12. The process as claimed in claim 1, wherein the temperature of the first condensing means is 260-290 ℃.
13. The process as claimed in claim 1, wherein the temperature of the first reboiling unit is 310-330 ℃.
14. The process of claim 1, wherein the light component in step (II) comprises hexachlorobenzene.
15. The process of claim 1, wherein a second jacket is provided outside the cavity of the first front end capture device.
16. The process according to claim 15, wherein water or cold air is introduced into the second jacket.
17. The process of claim 1, wherein the temperature within the first front end capture unit is controlled to be in the range of 40 ℃ to 150 ℃.
18. The process of claim 17, wherein the temperature within the first front end capture device is controlled to be in the range of 60-80 ℃.
19. The process as claimed in claim 1, wherein the second upper heating temperature is 280-300 ℃.
20. The process as claimed in claim 1, wherein the second lower heating temperature is 320-330 ℃.
21. The process of claim 1, wherein the overhead vacuum of the second rectification column is 0.06 to 0.08 MPa.
22. The process as claimed in claim 1, wherein the temperature of the second condensing means is 260-290 ℃.
23. The process as claimed in claim 1, wherein the temperature of the second reboiling device is 310-330 ℃.
24. The process according to claim 1, wherein the low boiling substance in step (III) comprises hexachlorobenzene.
25. The process of claim 1, wherein a third jacket is provided outside the cavity of the second front end capture device.
26. The process according to claim 25, wherein water or cold air is introduced into the third jacket.
27. The process of claim 1, wherein the temperature within the second front end capture unit is controlled to be in the range of 40 ℃ to 150 ℃.
28. The process of claim 27, wherein the temperature within the second front end capture device is controlled to be in the range of 60-80 ℃.
29. The process of claim 1, wherein the refining kettle in the step (IV) has a vacuum degree of 0.07-0.09 MPa.
30. The process as claimed in claim 1, wherein the temperature of the second thermal oil is 300-330 ℃.
31. The process according to claim 1, wherein the condensation is carried out in a condensing unit.
32. The process of claim 31, wherein the condensing medium of the condensing unit is a heat transfer oil.
33. The process as claimed in claim 32, wherein the temperature of the condensing medium is 240-330 ℃.
34. The process as set forth in claim 33 wherein the temperature of said condensing medium is 250 ℃ to 280 ℃.
35. The process of claim 1, wherein a third heat transfer oil is used to heat the product receiving tank.
36. The process as claimed in claim 35, wherein the temperature of the third thermal oil is 240-330 ℃.
37. The process as claimed in claim 36, wherein the temperature of the third thermal oil is 250-280 ℃.
38. The process of claim 1, wherein step (iv) further comprises: and (3) desublimating the incompletely condensed chlorothalonil product in a product catching device arranged in the subsequent process flow of the product receiving kettle.
39. The process of claim 38, wherein the product capture device is heated with a fourth heat transfer oil.
40. The process of claim 38 wherein a fourth jacket is provided outside the product capture device chamber.
41. The process of claim 40, wherein water or cold air is introduced into the fourth jacket.
42. The process of claim 38 wherein the temperature of the product capture device is controlled to be in the range of 40-150 ℃.
43. The process of claim 42 wherein the temperature of the product capture device is controlled to be between 60 ℃ and 80 ℃.
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