CN109369454B

CN109369454B - Continuous rectification and purification system and method for unqualified chlorothalonil

Info

Publication number: CN109369454B
Application number: CN201811486087.2A
Authority: CN
Inventors: 王海波; 李强; 王春云
Original assignee: Jiangsu Xinhe Agrochemical Co ltd
Current assignee: Jiangsu Xinhe Agrochemical Co ltd
Priority date: 2018-12-06
Filing date: 2018-12-06
Publication date: 2023-11-24
Anticipated expiration: 2038-12-06
Also published as: CN109369454A

Abstract

The invention provides a continuous rectification purification system and a continuous rectification purification method for unqualified chlorothalonil, wherein the system comprises a feeding unit, a continuous rectification unit and a refining unit which are sequentially connected; the feeding unit comprises a melting device, a metering pump and a feeding overheat device which are connected in sequence; the continuous rectification unit comprises a first rectification tower and a second rectification tower which are sequentially connected; the refining unit comprises a refining kettle, a product condensing device and a product receiving kettle which are connected in sequence; the bottom of the refining kettle is provided with a slag discharge port, and the bottom of the product receiving kettle is provided with a discharge port for connecting a slicer. According to the invention, a continuous rectification process is combined with a refining kettle for refining and purifying, so that most of chlorothalonil in the unqualified chlorothalonil product is recovered, and hazardous wastes in the unqualified chlorothalonil product are effectively removed.

Description

Continuous rectification and purification system and method for unqualified chlorothalonil

Technical Field

The invention belongs to the field of pesticide production, relates to a chlorothalonil rectification purification system and method, in particular to a disqualified chlorothalonil rectification purification system and method, and especially relates to a disqualified chlorothalonil continuous rectification purification system and method.

Background

The chlorothalonil is a protective bactericide with high efficiency, low toxicity, broad spectrum and low residue, is widely applied to the prevention and treatment of fungal diseases in agriculture and forestry, and particularly has very wide application in economic crops such as vegetables and fruits. It is reported by Japanese data that chlorothalonil can exert control effect on fifty-two diseases of thirty-more crops. In addition, chlorothalonil has important application in the mildew-proof industry field, such as the manufacture of mildew-proof paint and mildew-proof wallpaper, and mildew-proof of electric appliances, leather, wood and the like. Along with the continuous expansion of the domestic production scale of chlorothalonil, the chlorothalonil becomes one of large-tonnage good pesticide varieties in the world, and the sales situation in the international market is always in a hot market state. The chlorothalonil is defined in national standard GB/T9551-2017 in China as white powder, wherein the content of two main indexes is more than or equal to 97%, and the content of hexachlorobenzene is less than or equal to 40ppm as a qualified product. At present, in actual production, a certain amount of chlorothalonil with the content of 50-80 percent, high hexachlorobenzene content and yellow or green color can be produced. The standard product of the product is obtained by purifying and refining the unqualified chlorothalonil product, so that sales and sales of the product are greatly improved, enterprise profits are increased, and environmental protection pressure is reduced.

CN108329235a discloses a process method for producing high-purity chlorothalonil, the method comprises the steps of feeding raw materials containing chlorothalonil isophthalonitrile, trichloroisophthalonitrile, pentachlorobenzonitrile, hexachlorobenzene and water into a light component removal tower, extracting a mixture of chlorothalonil with the mass content of light components less than or equal to 0.01% and heavy components from the bottom of the light component removal tower, feeding the mixture into a product tower, and extracting a chlorothalonil product with the mass fraction more than or equal to 99.5% from the top of the product tower. The process method obtains the chlorothalonil product with the mass fraction of more than 99.5 percent. However, the fluctuation range of the content of the purified chlorothalonil cannot be too large, the content cannot be too low, and otherwise, the quality of the product is unstable.

Therefore, a more effective purification process with higher purification efficiency is urgently needed to purify unqualified chlorothalonil products with lower chlorothalonil content, and the unqualified chlorothalonil products with lower chlorothalonil content are refined to obtain qualified products, so that sales of the products are greatly improved, profit of enterprises is increased, the quantity of unqualified products is reduced, and environmental protection pressure is further relieved.

Disclosure of Invention

Aiming at the defects existing in the prior art, the invention aims to provide a continuous rectification purification system and method for unqualified chlorothalonil.

To achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, a continuous rectification and purification system for off-specification chlorothalonil comprises a feeding unit, a continuous rectification unit and a refining unit which are sequentially connected.

The feeding unit comprises a melting device, a metering pump and a feeding overheat device which are connected in sequence.

The continuous rectifying unit comprises a first rectifying tower and a second rectifying tower which are sequentially connected.

The refining unit comprises a refining kettle, a product condensing device and a product receiving kettle which are connected in sequence; the bottom of the refining kettle is provided with a slag discharge port, and the bottom of the product receiving kettle is provided with a discharge port for connecting a slicer.

According to the continuous rectification purification system provided by the invention, the refining and purification of the unqualified chlorothalonil product with lower chlorothalonil content is realized by adding the rectifying kettle on the basis of the traditional continuous rectification system, the unqualified chlorothalonil product with higher hexachlorobenzene content and lower chlorothalonil content can be refined and purified to obtain the refined chlorothalonil product with the chlorothalonil content of more than or equal to 97% and the hexachlorobenzene content of less than or equal to 10ppm, so that hazardous wastes in the unqualified chlorothalonil product are effectively removed, the harm of hexachlorobenzene in the product to soil and environment is reduced, and meanwhile, huge economic benefits are also generated, and the production cost is saved.

In a preferred embodiment of the present invention, the cavity material of the melting device is selected from corrosion-resistant alloy, preferably stainless steel or hastelloy, and more preferably monel 400.

Preferably, a heating component is arranged at the bottom of the cavity of the melting device.

Preferably, the heating element is an inner coil.

Preferably, a stirring member is provided inside the cavity of the melting apparatus.

Preferably, a jacket is arranged outside the cavity of the melting device.

Preferably, a heating medium is introduced into the jacket, and further preferably, the heating medium is heat conduction oil.

Preferably, the metering pump is a plunger metering pump.

Preferably, the feeding superheating device is a tube array heat exchanger.

Preferably, the cavity materials of the metering pump and the feeding superheating device are corrosion-resistant alloy, preferably stainless steel or hastelloy, and further preferably Monel 400.

Preferably, the metering pump and the feeding superheating device are made of the same or different materials.

As a preferred technical scheme of the invention, the feeding unit further comprises a feeding component connected with a top feeding hole of the melting device.

Preferably, the feeding assembly comprises a crude product bin and a conveying component which are connected in sequence.

Preferably, the conveying component is a screw conveyor.

Preferably, the crude material bin and the cavity of the conveying component are made of carbon steel or stainless steel, and further preferably 304 stainless steel, 316L stainless steel, Q235 or Q345.

Preferably, the crude product bin and the cavity of the conveying component are made of the same or different materials.

Preferably, the feeding unit further comprises a filter device, the inlet of the filter device is connected with the outlet at the bottom of the melting device, and the outlet of the filter device is connected with the inlet of the metering pump.

Preferably, the cavity material of the filtering device is corrosion resistant alloy, preferably stainless steel or hastelloy, and further preferably monel 400.

Preferably, the feeding unit further comprises a crude product recovery unit for recovering the partially evaporated crude chlorothalonil product, wherein an inlet of the crude product recovery unit is connected with an outlet of the metering pump, and an outlet of the crude product recovery unit is connected with a top feed back opening of the melting device.

Preferably, the crude product recovery unit comprises a melting middle tank and a melting trapping device which are connected in sequence; the top inlet of the melting middle tank is connected with the outlet of the metering pump, the bottom outlet of the melting middle tank is connected with the bottom inlet of the feeding overheat device, and the top outlet of the melting trapping device is connected with the top feed back opening of the melting device.

Preferably, the cavity material of the molten intermediate tank is selected from corrosion-resistant alloy, preferably stainless steel or hastelloy, and further preferably monel 400.

Preferably, a jacket is arranged outside the cavity of the melting middle groove.

Preferably, the cavity material of the melting and capturing device is selected from carbon steel or stainless steel, and further preferably 304 stainless steel, 316L stainless steel, Q235 or Q345.

Preferably, a baffle is arranged in the cavity of the melting and trapping device.

Preferably, a jacket is arranged outside the cavity of the melting and trapping device.

Preferably, a cooling medium is introduced into the jacket, and further preferably, the cooling medium is one or a combination of at least two of circulating water, cold air, low temperature water or frozen brine.

Preferably, a filtering component is arranged at the gas phase outlet of the melting and trapping device, and further preferably, the filtering component is a filter screen.

As a preferred technical scheme of the invention, the rectification unit comprises a first front cut trapping device connected with an outlet at the top of the first rectification column.

Preferably, the rectification unit further comprises a second front-end trapping device connected to the top outlet of the second rectification column.

Preferably, the cavity materials of the first front-end fraction trapping device and the second front-end fraction trapping device are selected from carbon steel or stainless steel, and further preferably 304 stainless steel, 316L stainless steel, Q235 or Q345.

Preferably, the first front-end trapping device and the second front-end trapping device are the same or different in cavity materials.

Preferably, baffles are arranged in the cavities of the first front cut trapping device and the second front cut trapping device.

Preferably, jackets are arranged outside the cavities of the first front-end fraction trapping device and the second front-end fraction trapping device.

Preferably, a cooling medium is introduced into the jacket, and further preferably, the cooling medium is selected from one or a combination of at least two of cooling water, cold air, low temperature water or chilled brine.

Preferably, the gas phase outlets of the first and second front-end trapping devices are provided with filter elements.

Preferably, the filter component is a filter screen.

Preferably, the cavity materials of the first rectifying tower and the second rectifying tower are corrosion resistant alloy, preferably stainless steel or hastelloy, and further preferably monel 400.

Preferably, the first rectifying tower and the second rectifying tower are the same or different in cavity materials.

Preferably, the first rectifying tower and the second rectifying tower are filled with filler in the cavities.

Preferably, tower plates are arranged in the cavities of the first rectifying tower and the second rectifying tower.

Preferably, the outer sides of the cavities of the first rectifying tower and/or the second rectifying tower are provided with heat preservation components, and further preferably, the outer sides of the cavities of the first rectifying tower and the second rectifying tower are provided with heat preservation components.

Preferably, the heat-insulating member is a heat tracing pipe.

Preferably, the top parts of the first rectifying tower and the second rectifying tower are provided with condensing devices, and further preferably, the condensing devices are tubular condensers.

Preferably, reboiling devices are arranged at the bottoms of the first rectifying tower and the second rectifying tower, and further preferably, the reboiling devices are tubular reboilers.

As a preferable technical scheme of the invention, the refining kettle comprises a refining kettle cavity and a jacket arranged outside the refining kettle cavity.

Preferably, the cavity material of the refining kettle is corrosion-resistant alloy, preferably stainless steel or hastelloy, and more preferably monel 400.

Preferably, a stirring component is arranged in the cavity of the refining kettle.

Preferably, a heating component is further arranged at the bottom of the cavity of the refining kettle, and further preferably, the heating component is an inner coil pipe.

Preferably, the product condensing device is a tube array heat exchanger.

Preferably, the material of the cavity of the product condensing device and the product receiving kettle is one of stainless steel, monel 400 or hastelloy.

Preferably, the material of the cavity of the product condensing device and the material of the cavity of the product receiving kettle are the same or different.

As a preferred embodiment of the present invention, the system further comprises a product capturing unit connected to the outlet of the refining unit.

Preferably, the product capturing unit comprises a first product capturing device and a second product capturing device which are connected in sequence.

Preferably, the cavity materials of the first product capturing device and the second product capturing device are selected from carbon steel or stainless steel, and further preferably 304 stainless steel, 316L stainless steel, Q235 or Q345.

Preferably, the first product capturing device and the second product capturing device are made of the same or different cavity materials.

Preferably, baffles are arranged in the cavities of the first product capturing device and the second product capturing device.

Preferably, jackets are arranged outside the cavities of the first product capturing device and the second product capturing device.

Preferably, the jacket is filled with a condensing medium, and further preferably, the condensing medium is selected from one or a combination of at least two of circulating water, cold air, low temperature water or chilled brine.

Preferably, the gas phase outlet of the first product capturing device and/or the second product capturing device is provided with a filter component, and further preferably, the gas phase outlet of the first product capturing device and the gas phase outlet of the second product capturing device are provided with filter components.

Preferably, the filter element is a filter screen.

As a preferred embodiment of the present invention, the system further comprises a front-end capture unit connected to the outlet of the continuous rectification unit.

Preferably, the front cut trapping unit comprises a first front cut trapping device and a second front cut trapping device; the top inlet of the first front cut trapping device is connected with the top extraction outlet of the first rectifying tower, and the top inlet of the second front cut trapping device is connected with the top extraction outlet of the second rectifying tower.

Preferably, the cavity materials of the first front-end fraction trapping device and the second front-end fraction trapping device are carbon steel or stainless steel, and further preferably 304 stainless steel, 316L stainless steel, Q235 or Q345.

Preferably, jackets are arranged on the outer sides of the cavities of the first front cut trapping device and the second front cut trapping device.

Preferably, a cooling medium is introduced into the jacket, and further preferably, the cooling medium is selected from one or a combination of at least two of cooling water, cold air, low temperature water and chilled brine.

Preferably, the gas phase outlet of the first front cut trapping device and/or the second front cut trapping device is provided with a filter element, and further preferably, the gas phase outlets of the first front cut trapping device and the second front cut trapping device are provided with filter elements.

Preferably, the filter component is a filter screen.

As a preferred technical scheme of the invention, the system further comprises a vacuumizing unit, wherein the vacuumizing unit comprises a first front-end vacuum pump, a second front-end vacuum pump and a product vacuum pump, an inlet of the first front-end vacuum pump is connected with a top outlet of the first front-end capturing device, an inlet of the second front-end vacuum pump is connected with a top outlet of the second front-end capturing device, and the product vacuum pump is connected with a top outlet of the second product capturing device.

Preferably, the first forefraction vacuum pump, the second forefraction vacuum pump and the product vacuum pump are selected from a water ring vacuum pump, a piston vacuum pump or a Roots vacuum pump.

Preferably, the second front-end vacuum pump and the product vacuum pump are of the same or different types.

In a second aspect, the present invention provides a continuous rectification purification method of off-specification chlorothalonil, the method being carried out in a system according to the first aspect, the method comprising:

passing the unqualified chlorothalonil product through a feeding unit, and feeding the unqualified chlorothalonil product from the middle of the first rectifying tower;

(II) light components are extracted from the top of the first rectifying tower and enter a first front-end fraction trapping device to be desublimated, and heavy components are fed from the middle of the second rectifying tower;

(III) extracting low-boiling-point substances in the heavy components obtained in the step (II) from the top of the second rectifying tower, enabling the low-boiling-point substances to enter a second front-end fraction trapping device for desublimation, and extracting crude chlorothalonil from the bottom of the second rectifying tower;

(IV) introducing the crude chlorothalonil obtained in the step (III) into a refining kettle, steaming out the refined chlorothalonil therein, condensing the refined chlorothalonil by a product condensing device, and collecting the condensed product into a product receiving kettle to obtain solid refined chlorothalonil;

The disqualified chlorothalonil product comprises chlorothalonil and hexachlorobenzene, wherein the content of the chlorothalonil is 65-80%, for example, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79% or 80%; the hexachlorobenzene content is 100-3000ppm, for example 200ppm, 400ppm, 600ppm, 800ppm, 1000ppm, 1200ppm, 1400ppm, 1600ppm, 1800ppm, 2000ppm, 2200ppm, 2400ppm, 2600ppm or 2800ppm.

The invention refines the unqualified chlorothalonil product again on the basis of the traditional continuous rectification purification process, thereby realizing the refining and purification of the chlorothalonil product with lower chlorothalonil content. The method comprises the steps of rectifying the raw chlorothalonil product in a first rectifying tower to remove most of low-boiling-point hazardous wastes such as hexachlorobenzene and the like in the chlorothalonil product, rectifying the raw chlorothalonil product in a second rectifying tower to remove the residual hexachlorobenzene in the residual components, and finally introducing crude chlorothalonil containing heavy-component hazardous wastes such as tetrachloro-terephthalonitrile and the like into a refining kettle to refine, steaming out the refined chlorothalonil in the refining kettle, wherein the heavy-component hazardous wastes are left in the refining kettle, deslagging and bagging the raw chlorothalonil product, treating or recycling the steamed refined chlorothalonil, condensing the distilled refined chlorothalonil to obtain a solid refined chlorothalonil product, and refining the unqualified chlorothalonil product with higher content of hexachlorobenzene and lower 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 10 ppm.

Preferably, the melting device, the melting intermediate tank and the feeding superheating device are heated by heat transfer 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 ℃.

Preferably, the feed is a bubble point feed.

Preferably, the step (I) further comprises the step of sublimating the partially evaporated off-grade chlorothalonil product in the melting kettle through a melting trapping device, and recycling the off-grade chlorothalonil product to the melting device.

Preferably, the temperature in the melt-trapping device is controlled to 40-150deg.C, for example, 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.

Preferably, the first rectifying tower in step (I) and step (II) is heated in two stages, namely an upper stage and a lower stage, wherein the heating temperature of the upper stage is 260-330 ℃, such as 260 ℃, 270 ℃, 280 ℃, 290 ℃, 300 ℃, 310 ℃, 320 ℃ or 330 ℃, preferably 280-300 ℃; the lower heating temperature is 300-350deg.C, such as 300 deg.C, 305 deg.C, 310 deg.C, 315 deg.C, 320 deg.C, 325 deg.C, 330 deg.C, 335 deg.C, 340 deg.C, 345 deg.C or 350 deg.C, preferably 310-330 deg.C.

Preferably, the vacuum degree of the top front fraction of the first rectifying tower is 0.05-0.095MPa, for example, 0.05MPa, 0.055MPa, 0.06MPa, 0.065MPa, 0.07MPa, 0.075MPa, 0.08MPa, 0.085MPa, 0.09MPa or 0.095MPa, preferably 0.06-0.07MPa.

Preferably, the temperature of the first rectifying column overhead condensing unit is 250-330 ℃, for example, 250 ℃, 260 ℃, 270 ℃, 280 ℃, 290 ℃, 300 ℃, 310 ℃, 320 ℃ or 330 ℃, preferably 260-290 ℃.

Preferably, the temperature of the first rectifying column bottom reboiling device is 310-350 ℃, for example 310 ℃, 315 ℃, 320 ℃, 325 ℃, 330 ℃, 335 ℃, 340 ℃, 345 ℃ or 350 ℃, preferably 320-330 ℃.

Preferably, the light component of step (II) contains hexachlorobenzene.

Preferably, the temperature in the first front-end 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 ℃.

Preferably, the second rectifying tower in step (II) and step (III) is divided into an upper section and a lower section, wherein the upper section heating temperature is 260-330 ℃, such as 260 ℃, 270 ℃, 280 ℃, 290 ℃, 300 ℃, 310 ℃, 320 ℃ or 330 ℃, preferably 280-300 ℃; the lower heating temperature is 300-350deg.C, such as 300 deg.C, 305 deg.C, 310 deg.C, 315 deg.C, 320 deg.C, 325 deg.C, 330 deg.C, 335 deg.C, 340 deg.C, 345 deg.C or 350 deg.C, preferably 310-330 deg.C.

Preferably, the vacuum degree of the top front fraction of the second rectifying tower is 0.05-0.095MPa, for example, 0.05MPa, 0.055MPa, 0.06MPa, 0.065MPa, 0.07MPa, 0.075MPa, 0.08MPa, 0.085MPa, 0.09MPa or 0.095MPa, preferably 0.06-0.08MPa.

Preferably, the temperature of the second rectifying column overhead condensing unit is 250-330 ℃, for example, 250 ℃, 260 ℃, 270 ℃, 280 ℃, 290 ℃, 300 ℃, 310 ℃, 320 ℃ or 330 ℃, preferably 260-290 ℃.

Preferably, the temperature of the second rectifying column bottom reboiling device is 310-350 ℃, for example 310 ℃, 315 ℃, 320 ℃, 325 ℃, 330 ℃, 335 ℃, 340 ℃, 345 ℃ or 350 ℃, preferably 320-330 ℃.

Preferably, the low-boiling residue in step (III) contains hexachlorobenzene.

Preferably, the temperature in the second front-end 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 ℃.

Preferably, the vacuum degree of the refining kettle in the step (IV) is 0.05-0.095MPa, for example, 0.05MPa, 0.055MPa, 0.06MPa, 0.065MPa, 0.07MPa, 0.075MPa, 0.08MPa, 0.085MPa, 0.09MPa or 0.095MPa, preferably 0.07-0.09MPa.

Preferably, the refining kettle is heated by heat conduction oil.

Preferably, the product condensing device is condensed by adopting heat conduction oil.

Preferably, the temperature of the heat transfer oil is 240-330 ℃, for example 240 ℃, 250 ℃, 260 ℃, 270 ℃, 280 ℃, 290 ℃, 300 ℃, 310 ℃, 320 ℃ or 330 ℃, preferably 250-280 ℃.

Preferably, the product receiving tank is heated by heat transfer oil.

Preferably, the step (iv) further comprises: and (3) desublimating the incompletely condensed chlorothalonil refined product in the first product trapping device and the second product trapping device.

Preferably, the temperature of the first and second product capturing devices is controlled to be 40-150 ℃, for example, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃, or 150 ℃, preferably 60-80 ℃.

In a third aspect, the present invention provides a refined chlorothalonil prepared by an extraction method according to the second aspect;

preferably, the refined chlorothalonil comprises chlorothalonil and hexachlorobenzene; wherein the content of the chlorothalonil is more than or equal to 97%, for example, 97%, 97.5%, 98%, 98.5%, 99% or 99.5%; the hexachlorobenzene content is 10% or less, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%.

The numerical ranges recited herein include not only the above-listed point values, but also any point values between the above-listed numerical ranges that are not listed, and are limited in space and for the sake of brevity, the present invention is not intended to be exhaustive of the specific point values that the stated ranges include.

Compared with the prior art, the invention has the beneficial effects that:

according to the invention, a continuous rectification process is combined with a refining kettle for refining and purifying, most of chlorothalonil in the unqualified chlorothalonil product is recovered, and hazardous wastes such as hexachlorobenzene, terephthalonitrile and the like in the unqualified chlorothalonil product are removed. The content of chlorothalonil in the obtained refined chlorothalonil product is more than 97%, the content of hexachlorobenzene is less than 10ppm and is far higher than the national standard, and meanwhile, the folded and distilled yield is more than 80%, so that the threat of hazardous waste to the environment is reduced, and meanwhile, great economic value is generated.

Drawings

FIG. 1 is a flow chart of a continuous rectification and purification system for unqualified chlorothalonil according to an embodiment of the invention.

Wherein, 1-a crude product bin; 2-feeding screw conveyor; 3-melting kettle; 4-a pipeline filter; 5-a metering pump; 6-a melting intermediate tank; 7-feeding a superheater of the rectifying tower; 8-a first rectifying tower; 9-a second rectifying tower; 10-refining kettle; 11-a product condenser; 12-a product receiving kettle; 13-a melt catcher; 14-a first front end trap; 15-a second front end trap; 16-a first product catcher; 17-a second product catcher; 18-a first forefraction vacuum pump; 19-a second forefraction vacuum pump; 20-product vacuum pump.

Detailed Description

The technical scheme of the invention is further described below by the specific embodiments with reference to the accompanying drawings.

In one embodiment, the invention provides a continuous rectification and purification system for off-grade chlorothalonil, as shown in fig. 1, which comprises a feeding unit, a continuous rectification unit and a refining unit which are sequentially connected.

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 middle tank 6 and a rectifying tower feeding superheater 7 which are connected in sequence; the feeding unit further comprises a melting catcher 13, wherein the top inlet of the melting catcher 13 is connected with the top outlet of the melting middle tank 6, and the top outlet of the melting catcher 13 is connected with the top feed back opening of the melting kettle 3.

The cavity materials of the crude feed bin 1 and the feed screw conveyor 2 are selected from carbon steel or stainless steel, and can be selected from 304 stainless steel, 316L stainless steel, Q235 or Q345 by way of example.

The melting kettle 3 comprises a melting kettle cavity and a jacket arranged outside the melting kettle cavity; wherein the cavity of the melting kettle is made of corrosion-resistant alloy; and heat conduction oil is introduced into the jacket, and the melting kettle 3 further comprises an inner coil pipe positioned at the bottom of the cavity of the melting kettle and a stirring part positioned in the cavity of the melting kettle.

The cavity material of the pipe filter 4 is corrosion resistant alloy, and may be illustratively selected from stainless steel or hastelloy.

The metering pump 5 is a plunger metering pump, and the cavity material of the metering pump 5 is corrosion resistant alloy, and can be exemplified by stainless steel or hastelloy.

The melting middle tank 6 comprises a melting middle tank cavity and a jacket arranged outside the melting middle tank cavity; wherein the material of the molten intermediate tank cavity is corrosion resistant alloy, and can be exemplified by stainless steel or hastelloy; and heat conducting oil is introduced into the jacket.

The distillation column feed superheater 7 is a tube type heat exchanger, and the cavity material of the distillation column feed superheater 7 is corrosion resistant alloy, and can be illustratively selected from stainless steel or hastelloy.

The melt catcher 13 includes a melt catcher cavity and a jacket disposed outside the melt catcher cavity; wherein, the material of the melting catcher cavity is selected from carbon steel or stainless steel, a baffle is arranged in the cavity, a cooling medium is introduced into the jacket, and the cooling medium can be one or a combination of at least two of circulating water, cold air, low temperature water or frozen brine, and a filter screen is arranged at the 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 bottom discharge port of the first rectification tower 8 is connected with a middle section feed port of the second rectification tower 9; the inside of the cavity of the first rectifying tower 8 and the second rectifying tower 9 is filled with filler and is provided with a tower plate, the outside is provided with a heat tracing pipe, the tower tops of the first rectifying tower 8 and the second rectifying tower 9 are provided with tubular condensers, and the tower bottom is provided with tubular reboilers.

The continuous rectification unit further comprises a first front-end catcher 14 connected to the top outlet of the first rectification column 8, and a second front-end catcher 15 connected to the top outlet of the second rectification column 9.

The cavity materials of first front cut trap 14 and second front cut trap 15 are selected from carbon steel or stainless steel, and may be selected from 304 stainless steel, 316L stainless steel, Q235, or Q345, for example. The first front-end catcher 14 and the second front-end catcher 15 are provided with baffles inside the cavity, a jacket is arranged outside the cavity, and cooling medium is introduced into the jacket, wherein the cooling medium is selected from one or a combination of at least two of cooling water, cold air, low temperature water or frozen brine. A filter screen is also arranged at the gas phase outlet of the first front cut catcher 14 and the second front cut 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 outlet of the second rectifying tower 9, the bottom of the refining kettle 10 is provided with a slag discharge outlet, and the bottom of the product receiving kettle 12 is provided with a discharge outlet for connecting a slicer.

The refining kettle 10 is made of corrosion-resistant alloy, and can be illustratively selected from stainless steel or hastelloy, a stirring component is arranged in the cavity, an inner coil is arranged at the bottom of the cavity, a jacket is arranged at the outer side of the cavity, and heat conduction oil is introduced into the jacket.

The product condenser 11 is a tube heat exchanger, and the cavity materials of the product condenser 11 and the product receiving tank 12 are selected from corrosion resistant alloys, and may be exemplified by stainless steel or hastelloy.

The system further comprises a first product catcher 16 and a second product catcher 17 connected in sequence to the outlet of the refining unit.

The cavity material of the first product catcher 16 and the second product catcher 17 is selected from carbon steel or stainless steel, and may be exemplified by 304 stainless steel, 316L stainless steel, Q235 or Q345. The first product catcher 16 and the second product catcher 17 are provided with baffles in the inner parts and jackets outside, and condensing medium is introduced into the jackets, and the condensing medium is selected from one or a combination of at least two of circulating water, cold air, low temperature water or frozen brine. The gas phase outlets of the first product catcher 16 and the second product catcher 17 are provided with filter screens.

The system also comprises a front fraction trapping unit connected with the outlet of the continuous rectification unit; the front cut trapping unit comprises a first front cut trap 14 and a second front cut trap 15; wherein the top inlet of the first front cut catcher 14 is connected with the top outlet of the first rectifying tower 8, and the top inlet of the second front cut catcher 15 is connected with the top outlet of the second rectifying tower 9.

The cavity materials of first front cut trap 14 and second front cut trap 15 are selected from carbon steel or stainless steel, and may be selected from 304 stainless steel, 316L stainless steel, Q235, or Q345, for example. The first front cut catcher 14 and the second front cut catcher 15 are provided with baffles inside the cavity, jackets are arranged outside the cavities, cooling medium is introduced into the jackets, and the cooling medium is selected from one or a combination of at least two of cooling water, cold air, low temperature water and frozen brine. The gas phase outlets of the first front cut catcher 14 and the second front cut catcher 15 are provided with filter screens.

The system further comprises a first forefraction vacuum pump 18, a second forefraction vacuum pump 19 and a product vacuum pump 20; an inlet of the first forefraction vacuum pump 18 is connected to a top outlet of the first forefraction collector 14, an inlet of the second forefraction vacuum pump 19 is connected to a top outlet of the second forefraction collector 15, and the product vacuum pump 20 is connected to a top outlet of said second product collector 17.

The first forefraction vacuum pump 18, the second forefraction vacuum pump 19, and the product vacuum pump 20 are selected from the group consisting of a water ring vacuum pump, a piston vacuum pump, or a Roots vacuum pump.

In another specific embodiment, the invention also provides a continuous rectification purification method of unqualified chlorothalonil, which specifically comprises the following steps:

(1) A certain amount of unqualified chlorothalonil product is continuously conveyed into a melting kettle 3 through a crude product bin 1 and a feeding screw conveyor 2.

(2) The unqualified chlorothalonil product is melted into liquid chlorothalonil in the melting kettle 3, filtered by the pipeline filter 4, conveyed into the melting intermediate tank 6 by the metering pump 5, heated to the bubble point temperature by the rectifying tower feeding superheater 7, and fed from the middle of the first rectifying tower 8.

(3) The liquid chlorothalonil enters the first rectifying tower 8 for rectifying operation, and a part of light components with high hexachlorobenzene content are extracted from the top of the first rectifying tower 8 and enter the first front cut catcher 14 for desublimation into solids. The remaining components are withdrawn from the bottom of the first rectification column 8 and fed from the middle of the second rectification column 9.

(4) The rest components in the step (3) are continuously subjected to rectification operation in the second rectification column 9, wherein a part of low-boiling-point substances with higher hexachlorobenzene content are extracted from the top of the second rectification column 9 and enter the second front-end catcher 15 to be sublimated into solids.

(5) Crude chlorothalonil extracted from the bottom of the second rectifying tower 9 flows into a refining kettle 10, refined chlorothalonil is distilled out of the refining kettle, condensed by a product condenser 11 and then collected into a product receiving kettle 12, and solid refined chlorothalonil is obtained and sliced and packaged by a slicer.

(6) The incompletely condensed gaseous chlorothalonil is sublimated 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 a qualified product, the chlorothalonil can be directly packaged in a bag, and if the chlorothalonil is a disqualified product, the chlorothalonil can be recycled and then subjected to centralized treatment.

Example 1

The embodiment provides a disqualified chlorothalonil continuous rectification purification system, wherein the cavity materials of a melting kettle 3, a pipeline filter 4, a metering pump 5, a melting middle tank 6, a rectification tower feeding superheater 7, a first rectification tower 8, a second rectification tower 9, a refining kettle, a product condenser 11 and a product receiving kettle 12 are all 304 stainless steel; the cavities of the melting catcher 13, the first front cut catcher 14, the second front cut catcher 15, the first product catcher 16 and the second product catcher 17 are made of carbon steel, and circulating cooling water is introduced into jackets of the five catchers; the first front-end vacuum pump 18, the second front-end vacuum pump 19 and the product vacuum pump 20 are water ring vacuum pumps; the connecting pipelines among all the devices are jacket pipelines and are made of 304 stainless steel.

The embodiment also provides a continuous rectification purification method of unqualified chlorothalonil, which specifically comprises the following steps:

(1) 3 tons of unqualified chlorothalonil products continuously enter a melting kettle 3 through a crude product storage bin 1 and a feeding screw conveyor 2, the oil temperature of heat conduction oil in a jacket of the melting kettle 3 is 330 ℃, wherein the chlorothalonil products contain 65.9% of chlorothalonil and 2850ppm of hexachlorobenzene.

(2) The unqualified chlorothalonil product is continuously melted into a liquid chlorothalonil product in the melting kettle 3, impurities in the liquid chlorothalonil product are filtered by the pipeline filter 4 and then continuously introduced into the melting intermediate tank 6 by the metering pump 5, the liquid chlorothalonil product is heated to the bubble point temperature by the feeding superheater 7 of the rectifying tower and then continuously enters the first rectifying tower 8 from the middle part of the first rectifying tower, and the oil temperature of heat conduction oil in jackets of the melting intermediate tank 6 and the feeding superheater 7 of the rectifying tower is 330 ℃. The partially evaporated off-grade chlorothalonil product in the melting kettle 3 enters a melting catcher 13 through a melting middle tank 6, is sublimated into solid and is recovered 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 cut catcher 14 for desublimation into solid, and the solid waste treatment is carried out after bagging; the remaining heavy components were withdrawn from the bottom of the first rectifying column 8, fed from the middle of the second rectifying column 9, the upper temperature of the first rectifying column 8 was 280 ℃, the lower temperature was 330 ℃, the outlet temperature of the overhead condenser was 260 ℃, the bottom reboiler temperature was 330 ℃, the vacuum degree of the overhead front cut was 0.07MPa, and the outlet temperature of the first front cut catcher 14 was 60 ℃.

(4) In the step (3), the heavy component fed from the middle of the second rectifying tower 9 is continuously rectified in the second rectifying tower 9, wherein low-boiling-point substances are extracted from the top of the second rectifying tower 9, enter a second front-end fraction catcher 15 for desublimation into solid, and are subjected to solid waste treatment after being packaged, and crude chlorothalonil is extracted from the bottom of the second rectifying tower 9. The upper temperature of the second rectifying tower 9 is 280 ℃, the lower temperature of the second rectifying tower 9 is 330 ℃, the outlet temperature of the tower top condenser is 260 ℃, the tower bottom reboiler temperature is 330 ℃, the vacuum degree of the tower top front cut is 0.08MPa, and the outlet temperature of the second front cut catcher 15 is 60 ℃.

(5) Crude chlorothalonil extracted from the bottom of the second rectifying tower 9 is introduced into a refining kettle 10, refined chlorothalonil is distilled out of the refining kettle, condensed by a product condenser 11 and then collected into a product receiving kettle 12, and solid refined chlorothalonil is obtained and sliced and packaged by a slicer. The temperature of conduction oil in the jacket of the refining kettle 10 is 330 ℃, the vacuum degree in the refining kettle 10 is 0.08MPa, the product condenser 11 and the product receiving kettle 12 are heated by adopting the conduction oil, and the temperature of the conduction oil is 260 ℃.

(6) The incompletely condensed gaseous chlorothalonil is sublimated 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 a qualified product, the chlorothalonil can be directly packaged in a bag, and if the chlorothalonil is a disqualified product, the chlorothalonil can be recycled and then subjected to centralized treatment. The outlet temperatures of the first product catcher 16 and the second product catcher 17 are 60 ℃.

The data of the chlorothalonil content, the hexachlorobenzene content, the rectification yield, the percentage of solid waste amount in the rectification raw material amount and the like in the refined chlorothalonil prepared in the embodiment are shown in table 1.

Example 2

The embodiment provides a disqualified chlorothalonil continuous rectification purification system, wherein the cavity materials of a melting kettle 3, a pipeline filter 4, a metering pump 5, a melting middle tank 6, a rectification tower feeding superheater 7, a first rectification tower 8, a second rectification tower 9, a refining kettle 10, a product condenser 11 and a product receiving kettle 12 are monel 400; the cavities of the melting catcher 13, the first front cut catcher 14, the second front cut catcher 15, the first product catcher 16 and the second product catcher 17 are made of stainless steel, and cold air is introduced into jackets of the five catchers; the first forefraction vacuum pump 18, the second forefraction vacuum pump 19 and the product vacuum pump 20 are piston vacuum pumps; the connecting pipelines between all the devices are jacket pipelines, and the material is Monel 400.

The embodiment also provides a continuous rectification and purification method of unqualified chlorothalonil, which is different from embodiment 1 in that the vacuum degree of the front fraction of the first rectification tower is changed to 0.055MPa, and other process operation parameters are the same as those of embodiment 1.

The summary data of the chlorothalonil content, the hexachlorobenzene content, the rectification yield, the percentage of solid waste amount in 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 example 1 is that the vacuum degree of the front fraction of the first rectifying tower is changed to 0.06MPa, and other process operation parameters are the same as those of example 1.

Example 4

The difference from example 1 is that the vacuum degree of the front fraction of the first rectifying tower is changed to 0.08MPa, and other process operation parameters are the same as those of example 1.

Example 5

The difference from example 1 is that the vacuum degree of the front fraction of the first rectifying tower is changed to 0.095MPa, and other process operation parameters are the same as those of example 1.

Example 6

The difference from example 1 is that the chlorothalonil product has a chlorothalonil content of 72.5% and a hexachlorobenzene content of 1350ppm, the vacuum degree of the second rectifying tower front cut is changed to 0.05MPa, and other process operation parameters are the same as those of example 1.

Example 7

The difference from example 1 is that the chlorothalonil product has a chlorothalonil content of 72.5% and a hexachlorobenzene content of 1350ppm, the vacuum degree of the second rectifying tower front cut is changed to 0.06MPa, and other process operation parameters are the same as those of example 1.

Example 8

The difference from example 1 is that the chlorothalonil product has a chlorothalonil content of 72.5% and a hexachlorobenzene content of 1350ppm, the vacuum degree of the second rectifying tower front cut is changed to 0.08MPa, and other process operation parameters are the same as those of example 1.

Example 9

The difference from example 1 is that the chlorothalonil product has a chlorothalonil content of 72.5% and a hexachlorobenzene content of 1350ppm, the vacuum degree of the second rectifying tower front cut is changed to 0.09MPa, and other process operation parameters are the same as those of example 1.

Example 10

The difference from example 1 is that the chlorothalonil content in the reject chlorothalonil product is 73.8%, the hexachlorobenzene content is 560ppm, the temperatures of the top condensers of the first rectifying tower 8 and the second rectifying tower 9 are changed to 250 ℃, the upper section temperature control of the tower body is changed to 260 ℃, the lower section temperature control of the tower body is changed to 300 ℃, the temperature of the bottom reboiler is 310 ℃, and other process operation parameters are the same as those of example 1.

Example 11

The difference from example 1 is that the chlorothalonil content in the reject chlorothalonil product is 73.8%, the hexachlorobenzene content is 560ppm, the temperatures of the top condensers of the first rectifying tower 8 and the second rectifying tower 9 are changed to 260 ℃, the upper section temperature control of the tower body is changed to 280 ℃, the lower section temperature control of the tower body is changed to 310 ℃, the temperature of the bottom reboiler is 320 ℃, and other process operation parameters are the same as those of example 1.

Example 12

The difference from example 1 is that the chlorothalonil content in the reject chlorothalonil product is 73.8%, the hexachlorobenzene content is 560ppm, the temperature of the top condensers of the first rectifying tower 8 and the second rectifying tower 9 is changed to 290 ℃, the temperature control of the upper section of the tower body is changed to 300 ℃, the temperature control of the lower section of the tower body is changed to 330 ℃, the temperature of the bottom reboiler is 330 ℃, and other process operation parameters are the same as those of example 1.

Example 13

The difference from example 1 is that the chlorothalonil content in the reject chlorothalonil product is 73.8%, the hexachlorobenzene content is 560ppm, the temperatures of the top condensers of the first rectifying tower 8 and the second rectifying tower 9 are changed to 320 ℃, the upper section temperature control of the tower body is changed to 330 ℃, the lower section temperature control of the tower body is changed to 350 ℃, the temperature of the bottom reboiler is 350 ℃, and other process operation parameters are the same as those of example 1.

Example 14

The difference from example 1 is that the chlorothalonil product contains 67.6% chlorothalonil, 2160ppm hexachlorobenzene, 260 ℃ of heat conduction oil temperature in the refining kettle 10, 0.05MPa of vacuum degree in the refining kettle 10, and other process operation parameters are the same as those of example 1.

Example 15

The difference from example 1 is that the chlorothalonil product has a chlorothalonil content of 67.6% and a hexachlorobenzene content of 2160ppm, the temperature of the conduction oil in the refining kettle 10 is changed to 300 ℃, the vacuum degree in the refining kettle 10 is 0.07MPa, and other process operation parameters are the same as those of example 1.

Example 16

The difference from example 1 is that the chlorothalonil product has a chlorothalonil content of 67.6% and a hexachlorobenzene content of 2160ppm, the temperature of the conduction oil in the refining kettle 10 is changed to 330 ℃, the vacuum degree in the refining kettle 10 is 0.09MPa, and other process operation parameters are the same as those of example 1.

Example 17

The difference from example 1 is that the chlorothalonil product has a chlorothalonil content of 67.6% and a hexachlorobenzene content of 2160ppm, the temperature of the conduction oil in the refining kettle 10 is changed to 350 ℃, the vacuum degree in the refining kettle 10 is 0.095MPa, and other process operation parameters are the same as those of example 1.

Example 18

The difference from example 1 is that the chlorothalonil product contains 79.6% chlorothalonil and 106ppm hexachlorobenzene, the temperature of the heat transfer oil in the melting kettle 3, the melting intermediate tank 6 and the feed superheater 7 is changed to 260 ℃, and other process operation parameters are the same as in example 1.

Example 19

The difference from example 1 is that the chlorothalonil product contains 79.6% chlorothalonil and 106ppm hexachlorobenzene, the temperature of the heat transfer oil in the melting kettle 3, the melting intermediate tank 6 and the feed superheater 7 is changed to 350 ℃, and other process operation parameters are the same as in example 1.

Comparative example 1

CN108329235a describes a process for the purification of high purity chlorothalonil, wherein example 1 provides a process for the purification of chlorothalonil comprising: the raw material is a chlorothalonil product containing 95.2 percent of chlorothalonil, the operation pressure of the first rectifying tower is 1KPa, the temperature of the top of the tower is 200 ℃, and the temperature of the bottom of the tower is 345 ℃; the second rectification column was operated at an absolute pressure of 1KPa, a top 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 conduction oil, and the temperature of the heat conduction oil is 150 ℃; the condensing medium of the condenser communicated with the top of the second rectifying tower is heat conduction oil, and the temperature of the heat conduction oil is 260 ℃.

In this comparative example, the raw material chlorothalonil was replaced with a chlorothalonil product containing 65.9% chlorothalonil and 2850ppm hexachlorobenzene, and the other process operation parameters were the same as those of example 1 in CN108329235 a.

The summary data of the chlorothalonil content, the hexachlorobenzene content, the rectification yield, the percentage of the solid waste amount in the rectification raw material amount and the like in the refined chlorothalonil prepared in the comparative example are shown in table 1.

TABLE 1

Comprehensive analysis of examples 1-19 and comparative example 1 shows that the chlorothalonil content in the unqualified chlorothalonil provided by the embodiment of the invention is 65-80%, and the chlorothalonil content in the refined chlorothalonil product obtained after the purification operation is over 97%, which accords with the national standard of GB/T9551-2017 on the chlorothalonil product. In contrast, in the process method provided by CN108329235a in comparative example 1, when only the raw materials in the process method are replaced by the unqualified chlorothalonil product with lower chlorothalonil content (the unqualified chlorothalonil containing 65.9% of chlorothalonil), the obtained refined chlorothalonil product cannot reach the national standard, so that the process method provided by comparative example cannot be considered to be capable of effectively solving the problem of purifying the unqualified chlorothalonil product with too low chlorothalonil content.

The applicant declares that the above is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be apparent to those skilled in the art that any changes or substitutions that are easily conceivable within the technical scope of the present invention disclosed by the present invention fall within the scope of the present invention and the disclosure.

Claims

1. The device is characterized by comprising a feeding unit, a continuous rectifying unit and a refining unit which are connected in sequence;

the feeding unit comprises a melting device, a metering pump and a feeding overheat device which are connected in sequence;

the continuous rectification unit comprises a first rectification tower and a second rectification tower which are sequentially connected;

the refining unit comprises a refining kettle, a product condensing device and a product receiving kettle which are connected in sequence; the bottom of the refining kettle is provided with a slag discharge port, and the bottom of the product receiving kettle is provided with a discharge port for connecting a slicer;

the unqualified chlorothalonil comprises chlorothalonil and hexachlorobenzene, wherein the content of the chlorothalonil is 65-80%, and the content of the hexachlorobenzene is 100-3000ppm;

the operation method of the device comprises the following steps:

passing off-grade chlorothalonil through a feeding unit, and feeding from the middle of the first rectifying tower;

light components in the product are extracted from the top of the first rectifying tower and enter a first front-end fraction trapping device for desublimation, and heavy components in the product are fed from the middle of the second rectifying tower;

And (IV) introducing the crude chlorothalonil obtained in the step (III) into a refining kettle, steaming out the refined chlorothalonil therein, condensing the refined chlorothalonil by a product condensing device, and collecting the condensed product into a product receiving kettle to obtain the solid refined chlorothalonil.

2. The apparatus of claim 1, wherein the cavity material of the melting apparatus is selected from the group consisting of corrosion resistant alloys.

3. Purification device according to claim 1, characterized in that the bottom of the chamber of the melting device is provided with a heating element.

4. A purification apparatus according to claim 3, wherein the heating means is an inner coil.

5. Purification device according to claim 1, characterized in that the melting device is provided with stirring means inside its cavity.

6. The purifying apparatus according to claim 1, wherein a jacket is provided outside a cavity of the melting apparatus;

and a heating medium is introduced into the jacket.

7. The purification apparatus of claim 1, wherein the metering pump is a plunger metering pump.

8. The purification apparatus of claim 1, wherein the feed superheating apparatus is a shell and tube heat exchanger.

9. The purification device of claim 1, wherein the cavities of the metering pump and the feed superheater are made of corrosion resistant alloy.

10. The purification apparatus of claim 9, wherein the metering pump and the feed superheating apparatus are of the same or different materials.

11. The apparatus of claim 1, wherein the feed unit further comprises a feed assembly coupled to the top feed port of the melting apparatus.

12. The purifying apparatus of claim 11, wherein the feed assembly includes a crude feed bin and a transport member connected in series.

13. The purification apparatus of claim 12, wherein the conveying member is a screw conveyor.

14. The purifying apparatus of claim 12, wherein the crude feed bin and the cavity of the transport member are selected from carbon steel or stainless steel.

15. The purifying apparatus of claim 14, wherein the crude feed bin and the transporting member are made of 304 stainless steel, 316L stainless steel, Q235 or Q345.

16. The purifying apparatus of claim 12, wherein the crude material bin and the cavity of the conveying member are the same or different.

17. The purification apparatus of claim 1, wherein the feed unit further comprises a filter device, the filter device inlet being connected to the melt device bottom outlet, the filter device outlet being connected to the metering pump inlet.

18. The purifying apparatus of claim 17, wherein the cavity of the filter is made of corrosion resistant alloy.

19. The purification apparatus according to claim 1, wherein the feed unit further comprises a crude recovery unit for recovering a partially evaporated crude chlorothalonil, an inlet of the crude recovery unit being connected to the metering pump outlet, and an outlet of the crude recovery unit being connected to a top feed back of the melting apparatus.

20. The purification apparatus of claim 19, wherein the crude recovery unit comprises a melt intermediate tank and a melt capture device connected in sequence; the top inlet of the melting middle tank is connected with the outlet of the metering pump, the bottom outlet of the melting middle tank is connected with the bottom inlet of the feeding overheat device, and the top outlet of the melting trapping device is connected with the top feed back opening of the melting device.

21. The purification apparatus of claim 20, wherein the molten intermediate tank has a cavity material selected from the group consisting of corrosion resistant alloys.

22. The purifying apparatus of claim 20, wherein a jacket is provided outside the cavity of the molten intermediate tank;

And a heating medium is introduced into the jacket.

23. The purification apparatus of claim 20, wherein the chamber material of the melt-trapping device is selected from carbon steel or stainless steel.

24. The purification apparatus of claim 20, wherein the melt-trapping device has a cavity made of 304 stainless steel, 316L stainless steel, Q235, or Q345.

25. The purification apparatus of claim 20, wherein a baffle is disposed within a cavity of the melt-trapping device.

26. The purification apparatus of claim 20, wherein a jacket is provided outside the chamber of the melt-trapping apparatus;

and a cooling medium is introduced into the jacket.

27. The purification apparatus of claim 20, wherein a filter element is provided at a gas phase outlet of the melt-trapping device.

28. The apparatus of claim 1, wherein the rectification unit includes a first front-end capture device connected to the first rectification column top outlet;

the rectification unit also comprises a second front cut trapping device connected with the outlet at the top of the second rectification tower.

29. The purification apparatus of claim 28, wherein the first and second front-end trapping devices have a cavity made of a material selected from the group consisting of carbon steel and stainless steel.

30. The purification apparatus of claim 29, wherein the first and second front-end capture devices have a cavity made of 304 stainless steel, 316L stainless steel, Q235, or Q345;

and the cavity materials of the first front cut trapping device and the second front cut trapping device are the same or different.

31. The purification apparatus of claim 28, wherein the chambers of the first and second front cut trapping apparatuses are provided with baffles.

32. The purification apparatus of claim 28, wherein the first and second front-end trapping apparatuses are jacketed outside of the chamber;

a cooling medium is introduced into the jacket;

the cooling medium is selected from one or a combination of at least two of cooling water, cold air, low temperature water or chilled brine.

33. The purification apparatus of claim 28, wherein the gas phase outlets of the first and second front-end trapping apparatuses are provided with a filter element;

the filtering component is a filter screen.

34. The purifying apparatus of claim 28, wherein the cavities of the first rectifying column and the second rectifying column are made of corrosion resistant alloy.

35. The purification apparatus of claim 28, wherein the first rectification column and the second rectification column are each filled with a packing material within their cavities.

36. The purifying apparatus of claim 28, wherein trays are disposed within the cavities of the first rectifying column and the second rectifying column.

37. Purification device according to claim 1, characterized in that the first rectifying column and/or the second rectifying column is provided with a heat-insulating member outside the cavity.

38. The purification apparatus of claim 37, wherein the insulating member is a heat trace pipe.

39. The purifying device according to claim 1, wherein condensing means are provided at the tops of the first rectifying column and the second rectifying column; the condensing device is a tube condenser.

40. The purifying apparatus according to claim 1, wherein reboiling means are provided at bottoms of the first rectifying column and the second rectifying column; the reboiling device is a tube type reboiler.

41. The apparatus of claim 1, wherein the refining vessel comprises a refining vessel cavity and a jacket disposed outside the refining vessel cavity.

42. The purifying apparatus of claim 41, wherein the chamber of the refining vessel is made of corrosion resistant alloy.

43. The purifying apparatus of claim 41, wherein a stirring member is provided inside a cavity of the purifying tank.

44. The purifying apparatus of claim 41, wherein the bottom of the chamber of the purifying kettle is further provided with a heating element; the heating component is an inner coil.

45. The purification apparatus of claim 41, wherein a heating medium is introduced into the jacket; the heating medium is heat conduction oil.

46. The purifying apparatus of claim 1, wherein the product condensing means is a tube array heat exchanger.

47. The purification apparatus of claim 46, wherein the product condensing means and the product receiving tank are formed of a material selected from the group consisting of stainless steel, monel 400 and hastelloy.

48. The purification apparatus of claim 47, wherein the product condensing means and the product receiving tank are formed of the same or different materials.

49. The apparatus of claim 1, further comprising a product capture unit connected to the refining unit outlet.

50. The purification apparatus of claim 49, wherein the product capture unit comprises a first product capture device and a second product capture device connected in sequence.

51. The purification apparatus of claim 50, wherein the first product capturing means and the second product capturing means are comprised of a cavity material selected from the group consisting of carbon steel and stainless steel.

52. The purification apparatus of claim 51, wherein the first product capturing device and the second product capturing device have a cavity made of 304 stainless steel, 316L stainless steel, Q235 or Q345;

the first product trapping device and the second product trapping device are the same or different in cavity materials.

53. The purifying apparatus of claim 51, wherein the first product capturing device and the second product capturing device are provided with baffles inside the chamber.

54. The purification apparatus of claim 51, wherein the first product capturing means and the second product capturing means are provided with jackets outside the chambers.

55. The purification apparatus of claim 54, wherein a condensing medium is introduced into the jacket; the condensing medium is selected from one or a combination of at least two of circulating water, cold air, low temperature water or chilled brine.

56. The purification apparatus of claim 51, wherein the first product capturing means and/or the second product capturing means are provided with a filter element at the gas phase outlet.

57. The purification apparatus of claim 56, wherein the filter component is a filter screen.

58. The purification apparatus of claim 1, further comprising a front end capture unit connected to the outlet of the continuous rectification unit.

59. The purification apparatus of claim 58, wherein said front end capture unit comprises a first front end capture device and a second front end capture device; the top inlet of the first front cut trapping device is connected with the top extraction outlet of the first rectifying tower, and the top inlet of the second front cut trapping device is connected with the top extraction outlet of the second rectifying tower.

60. The purification apparatus of claim 59, wherein the first and second front-end trapping devices have cavities made of carbon steel or stainless steel.

61. The purification apparatus of claim 60, wherein the first and second front-end capture devices comprise a cavity made of 304 stainless steel, 316L stainless steel, Q235, or Q345.

62. The purification apparatus of claim 61, wherein the first and second front-end trapping devices have cavities of the same or different materials.

63. The purification apparatus of claim 59, wherein the chambers of the first and second front cut trapping devices are provided with baffles.

64. The purifying apparatus of claim 59, wherein the first front-end trapping device and the second front-end trapping device are each provided with a jacket outside the chamber.

65. The purification apparatus of claim 64, wherein a cooling medium is introduced into the jacket; the cooling medium is selected from one or a combination of at least two of cooling water, cold air, low temperature water and frozen brine.

66. The purification apparatus of claim 59, wherein the first and/or second front-end trapping means comprises a filter element at the gas phase outlet.

67. The purifying apparatus of claim 66, wherein the filter element is a filter screen.

68. The purification apparatus of claim 1, further comprising a vacuum unit comprising a first forefraction vacuum pump, a second forefraction vacuum pump, and a product vacuum pump, wherein an inlet of the first forefraction vacuum pump is connected to a top outlet of the first forefraction capturing apparatus, an inlet of the second forefraction vacuum pump is connected to a top outlet of the second forefraction capturing apparatus, and the product vacuum pump is connected to a top outlet of the second product capturing apparatus.

69. The purifying apparatus of claim 68, wherein the first forefraction vacuum pump, the second forefraction vacuum pump, and the product vacuum pump are selected from the group consisting of a water ring vacuum pump, a piston vacuum pump, and a roots vacuum pump.

70. The purification apparatus of claim 69, wherein the second forefraction vacuum pump, and the product vacuum pump are of the same or different types.

71. A continuous rectification purification process of off-grade chlorothalonil, wherein the process is carried out in the apparatus of any one of claims 1 to 70, the process comprising:

The unqualified chlorothalonil comprises chlorothalonil and hexachlorobenzene, wherein the content of the chlorothalonil is 65-80%, and the content of the hexachlorobenzene is 100-3000ppm.

72. The continuous rectification purification method of claim 71, wherein said melting means, said intermediate tank and said feed superheater are heated by means of heat transfer oil.

73. The continuous rectification purification method of claim 72, wherein said heat transfer oil has a temperature of between 260 and 350 ℃.

74. The continuous rectification and purification method according to claim 73, wherein said heat transfer oil has a temperature of 300-330 ℃.

75. The continuous rectification purification method of claim 71, wherein said feed is a bubble point feed.

76. The continuous rectification purification method of claim 71, wherein step (i) further comprises de-sublimating said partially vaporized off-grade chlorothalonil in said melting vessel by means of a melt-down trap, and recycling said off-grade chlorothalonil to said melting vessel.

77. The continuous rectification purification method of claim 76, wherein the temperature in said melt-trapping device is controlled between 40 and 150 ℃.

78. The continuous rectification purification method of claim 77, wherein the temperature in said melt-trapping device is controlled between 60 and 80 ℃.

79. The continuous rectification and purification method according to claim 71, wherein said first rectification column in step (i) and step (ii) is divided into upper and lower heating stages, said upper heating stage being at a temperature of 260 to 330 ℃ and said lower heating stage being at a temperature of 300 to 350 ℃.

80. The continuous rectification purification method according to claim 71, wherein said first rectification column top front end vacuum level is in the range of 0.05 MPa to 0.095MPa.

81. The continuous rectification purification method according to claim 80, wherein the vacuum level of said first rectification column top front end is between 0.06 MPa and 0.07MPa.

82. The continuous rectification purification method according to claim 71, wherein the temperature of said first rectification column top condensing device is in the range of 250-330 ℃.

83. The continuous rectification purification method of claim 82, wherein said first rectification column top condensing device has a temperature of between 260 and 290 ℃.

84. The continuous rectification purification method according to claim 71, wherein said first rectification column bottom reboiling means has a temperature in the range of 310 to 350 ℃.

85. The continuous rectification purification method of claim 84, wherein said first rectification column bottom reboiling means has a temperature in the range of 320 to 330 ℃.

86. The continuous rectification purification method of claim 71, wherein said light component of step (ii) comprises hexachlorobenzene.

87. The continuous rectification purification method of claim 71, wherein the temperature in said first front end capture device is controlled between 40 and 150 ℃.

88. The continuous rectification purification method of claim 87, wherein the temperature in said first front-end trapping device is controlled between 60 and 80 ℃.

89. The continuous rectification and purification method according to claim 71, wherein said second rectification column in step (ii) and step (iii) is divided into upper and lower heating stages, said upper heating stage being at 260-330 ℃ and said lower heating stage being at 300-350 ℃.

90. The continuous rectification purification method according to claim 71, wherein said second rectification column top front end vacuum level is in the range of 0.05 MPa to 0.095MPa.

91. The continuous rectification purification method according to claim 90, wherein the vacuum level of the top front end of said second rectification column is between 0.06 MPa and 0.08MPa.

92. The continuous rectification purification method according to claim 71, wherein the temperature of said second rectification column top condensing device is in the range of 250-330 ℃.

93. The continuous rectification purification method of claim 92, wherein said second rectification column top condensing device has a temperature in the range of 260-290 ℃.

94. The continuous rectification purification method according to claim 71, wherein said second rectification column bottom reboiling means has a temperature in the range of 310 to 350 ℃.

95. The continuous rectification purification method of claim 94, wherein said second rectification column bottom reboiling means has a temperature in the range of 320 to 330 ℃.

96. The continuous rectification and purification method of claim 71, wherein said low boiling point material of step (III) comprises hexachlorobenzene.

97. The continuous rectification purification method of claim 71, wherein the temperature in said second front end capture device is controlled between 40 and 150 ℃.

98. The continuous rectification purification method of claim 97, wherein the temperature in said second front end capture device is controlled between 60 and 80 ℃.

99. The continuous rectification purification method according to claim 71, wherein said refining kettle of step (iv) has a vacuum level of 0.05 to 0.095MPa.

100. The continuous rectification purification method according to claim 99, wherein said refining kettle in step (iv) has a vacuum level of 0.07 to 0.09MPa.

101. The continuous rectification purification method according to claim 71, wherein said refining tank is heated with heat transfer oil;

the temperature of the heat conduction oil is 260-350 ℃.

102. The continuous rectification and purification method according to claim 71, wherein said product condensing means is condensed by using heat transfer oil; the temperature of the heat conduction oil is 240-330 ℃.

103. The continuous rectification purification method of claim 71, wherein said product receiving vessel is heated with heat transfer oil;

the temperature of the heat conduction oil is 240-330 ℃.

104. The continuous rectification purification method of claim 71, wherein said step (iv) further comprises: and (3) desublimating the refined chlorothalonil which is not completely condensed in the first product trapping device and the second product trapping device.

105. The continuous rectification and purification method of claim 104, wherein said first product capturing means and said second product capturing means are controlled at a temperature of between 40 ℃ and 150 ℃.

106. The continuous rectification and purification method of claim 105, wherein said first product capturing means and said second product capturing means are controlled at a temperature of between 60 and 80 ℃.