CN113735718A - Method and system for continuously purifying m-phenylenediamine - Google Patents
Method and system for continuously purifying m-phenylenediamine Download PDFInfo
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- CN113735718A CN113735718A CN202111133994.0A CN202111133994A CN113735718A CN 113735718 A CN113735718 A CN 113735718A CN 202111133994 A CN202111133994 A CN 202111133994A CN 113735718 A CN113735718 A CN 113735718A
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Abstract
The invention relates to a method and a system for continuously purifying m-phenylenediamine, wherein the method continuously purifies the m-phenylenediamine by the coupling and separation process of rectification and suspension melt crystallization, and can convert the raw materials entering a separation system into useful industrial products to the maximum extent; removing heavy components through a first rectifying tower, obtaining refined m-phenylenediamine through a second rectifying tower, obtaining m-phenylenediamine crystal slurry through suspension melting crystallization, and finally obtaining a m-phenylenediamine finished product through a solid-liquid separator. The method has the advantages that the purity of the obtained product is high and can reach more than 99.990%, the yield is more than 98%, and the system has the characteristics of good operation stability, low energy consumption, high automation degree and environmental protection.
Description
Technical Field
The invention belongs to the technical field of separation and purification, and particularly relates to a method and a system for continuously purifying m-phenylenediamine.
Background
M-phenylenediamine is an important dye intermediate, can be used for synthesizing various basic dyes, is also an important aromatic amine curing agent, and is widely applied to the fields of composite materials and plastics. With the rapid development of the polyaramid high-performance material and the aramid fiber material in recent years, the application of the m-phenylenediamine is newly expanded, the m-phenylenediamine has wide market prospect in the aspect of synthesizing the high-temperature resistant aramid fiber 1313, and simultaneously, new requirements and challenges are provided for the preparation of the high-quality m-phenylenediamine.
The traditional method for purifying m-phenylenediamine mostly adopts a rectification method or a crystallization method. For the rectification method, because the boiling point of impurities is too close to that of the m-phenylenediamine, the rectification separation difficulty is higher, more theoretical plates and larger reflux ratio are needed, the equipment investment and the operation energy consumption are higher, and the impurity removal rate is not high, so that the purification effect of the m-phenylenediamine is limited; for the crystallization method, because the m-phenylenediamine crystallization has a supercooling phenomenon, intermittent static crystallization or falling film crystallization is mostly adopted, and the crystallization can be induced only by bubbling or adding seed crystals into the system every time, so that the operation is complicated; in addition, the m-phenylenediamine product obtained by static crystallization or falling film crystallization is not high in purity and efficiency.
Disclosure of Invention
In order to overcome the defects of high energy consumption and high separation difficulty of a rectification method and the problems of complex operation and low purity and efficiency of a crystallization method in the separation method of m-phenylenediamine in the prior art, the invention provides a method and a system for continuously purifying m-phenylenediamine. The product obtained by the method has high purity, and the system has the characteristics of good operation stability, low energy consumption, high automation degree and environmental protection.
The technical scheme adopted by the invention is as follows: a method for continuously purifying m-phenylenediamine comprises the following steps:
s1: introducing the crude m-phenylenediamine raw material into a rectifying tower, and removing impurity components in the crude m-phenylenediamine raw material to obtain refined m-phenylenediamine;
s2: shunting the obtained refined m-phenylenediamine, and respectively introducing the shunted refined m-phenylenediamine into a first crystallizer and a second crystallizer; adding seed crystals or bubbling in the primary crystallization process of the second crystallizer; introducing the crystal slurry materials obtained by the first crystallizer and the second crystallizer into a first solid-liquid separator and a second solid-liquid separator respectively;
s3: the liquid phase separated by the second solid-liquid separator is circularly led into a second crystallizer, and the solid phase separated by the second solid-liquid separator is led into a first crystallizer;
s4: the liquid phase separated in the first solid-liquid separator is divided and then respectively introduced into a first crystallizer and a second crystallizer; and heating and washing the solid phase separated in the first solid-liquid separator to obtain the m-phenylenediamine product.
Preferably, in step S4, the steps of heating and washing the solid phase separated in the first solid-liquid separator to obtain m-phenylenediamine product are as follows:
s4.1: forming a crystal bed layer in the first solid-liquid separator from the solid phase separated in the first solid-liquid separator, washing and cleaning the crystal bed layer by circulating washing liquid at the bottom from bottom to top, and recrystallizing crystals under the action of the hot circulating washing liquid while replacing impurities on the surfaces of the crystals and between the crystals in the bed layer by the washing liquid;
s4.2: scraping the continuously growing crystal bed layer into powder by a scraper in the first solid-liquid separator, mixing the powder into circulating washing liquid, and heating the mixed circulating washing liquid to melt the powder into liquid;
s4.3: and (4) recycling a part of the liquid obtained in the step (S4.2) into the first solid-liquid separator to be continuously used as a recycling washing liquid, and discharging a part of the liquid as a m-phenylenediamine product.
Preferably, in step S4.3, the ratio of the liquid used as the recycle wash to the liquid discharged as the m-phenylenediamine product is 30: 1; a purity detection device is arranged on a pipeline for discharging the m-phenylenediamine product, and the m-phenylenediamine product can be discharged to a product collection area after the product detection purity reaches the standard.
Preferably, if the product detection purity does not reach the standard, the product is returned to the first crystallizer.
Preferably, the specific steps of obtaining the m-phenylenediamine in the step S1 are as follows:
s1.1: introducing a crude m-phenylenediamine raw material into a first rectifying tower, discharging heavy components extracted by the first rectifying tower to the outside of a system, and introducing m-phenylenediamine-rich obtained by the first rectifying tower into a second rectifying tower;
s1.2: and discharging the light components extracted by the second rectifying tower to the outside of the system to obtain the refined m-phenylenediamine extracted by the second rectifying tower.
Preferably, in step S3, a part of the liquid phase separated by the second solid-liquid separator is recycled and introduced into the second crystallizer, and a part of the liquid phase is introduced into the first rectifying tower.
Preferably, the liquid phase separated by the second solid-liquid separator is fed into the second crystallizer and fed into the first rectifying tower in a ratio of 95-90: 5-10.
Preferably, in step S2, the stirrers in the first crystallizer and the second crystallizer are both provided with wall scraping scrapers, the wall scraping scrapers scrape off thin layers of crystals formed in the first crystallizer and the second crystallizer, the thin layers of crystals are mixed into materials in the first crystallizer and the second crystallizer to form crystal slurry materials, and the crystal slurry materials formed in the first crystallizer and the second crystallizer enter the first solid-liquid separator and the second solid-liquid separator respectively.
A system for continuously purifying m-phenylenediamine comprises a rectifying tower and a crystallizer, wherein the crystallizer comprises a first crystallizer and a second crystallizer, an inlet of the first crystallizer is connected with an outlet of the rectifying tower, an outlet of the first crystallizer is connected with a first solid-liquid separator, a liquid phase outlet of the first solid-liquid separator is respectively connected with inlets of the first crystallizer and the second crystallizer, and a solid phase outlet of the first solid-liquid separator is connected with a product discharge pipe; the inlet of the second crystallizer is connected with the outlet of the rectifying tower, the outlet of the second crystallizer is connected with a second solid-liquid separator, the liquid phase outlet of the second solid-liquid separator is connected with the inlet of the second crystallizer, and the solid phase outlet of the second solid-liquid separator is connected with the inlet of the first crystallizer.
Preferably, the rectifying tower comprises a first rectifying tower and a second rectifying tower, an inlet of the first rectifying tower is connected with the raw material inlet pipe, a material outlet of the first rectifying tower is connected with an inlet of the second rectifying tower, and an impurity outlet of the first rectifying tower is connected with the first impurity discharging pipeline; a material outlet of the second rectifying tower is respectively connected with the first crystallizer and the second crystallizer, and an impurity outlet of the second rectifying tower is connected with a second impurity discharging pipeline; the liquid phase outlet of the second solid-liquid separator is also connected with the inlet of the first rectifying tower; the device comprises a first solid-liquid separator, a product discharge pipe, a circulating pump, a heating device and a circulating pump, wherein the circulating pump is arranged between the solid-phase outlet of the first solid-liquid separator and the product discharge pipe, the outlet of the circulating pump is connected with the first solid-liquid separator, the heating device is arranged between the first solid-liquid separator and the circulating pump, and the outlet of the circulating pump is further connected with a first rectifying tower and/or a second rectifying tower.
The invention has the following beneficial effects:
1) the invention provides a separation system for continuously purifying m-phenylenediamine by coupling rectification and suspension melting crystallization, which optimizes a purification route, improves the separation and purification efficiency, reduces the energy consumption of purification and improves the product yield by uniformly integrating the rectification and the suspension melting crystallization;
2) the separation method for continuously purifying the m-phenylenediamine by coupling the rectification and the suspension melt crystallization has the characteristics of forced scouring and washing of crystals, continuous and stable operation of operation, no need of additional seed crystal, stream regulation and control and the like, improves the product purity, improves the automation level of the operation, and enhances the production stability;
3) the m-phenylenediamine purification method is a continuous crystallization method, only crystal seeds or bubbles need to be added in the primary crystallization process in the second crystallizer, and in the subsequent continuous operation process, crystals in the crystallizers (the first crystallizer and the second crystallizer) are already in the system and are maintained in dynamic balance, and the crystal seeds or the bubbles do not need to be added to induce the crystals to be crystallized, so that the operation steps and the use of materials are saved;
4) the wall scraping scrapers are arranged in the crystallizers, and the wall scraping scrapers in the first crystallizer are responsible for scraping the crystallized part in the crystallizers, so that effective solid-liquid separation is carried out; the scraped wall scraper in the second crystallizer is responsible for scraping the crystals to increase the crystal content in the second crystallizer, so that the crystals are maintained in dynamic balance in the subsequent process of the system;
5) the invention is provided with the two-stage crystallizer and the two-stage solid-liquid separator, thereby improving the crystallization and separation efficiency and shortening the overall operation time of the system; through the combination of different routes, the materials are crystallized and separated for multiple times, and the purity of the m-phenylenediamine is improved through forced washing, the purity of the finally obtained m-phenylenediamine is more than 99.990%, and the total yield is more than 98%.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
FIG. 1 is a schematic flow chart of the system of the present invention.
In the figure: 1-a first crystallizer; 2-a second crystallizer; 3-a first solid-liquid separator; 4-a first solid-liquid separator liquid phase outlet; 5-a solid phase outlet of the first solid-liquid separator; 6-product discharge pipe; 7-a second solid-liquid separator; 8-a second solid-liquid separator liquid phase outlet; 9-a solid phase outlet of the second solid-liquid separator; 10-a first rectification column; 11-a second rectification column; 12-raw material inlet pipe; 13-a first rectifying tower material outlet; 14-a first rectification column impurity outlet; 15-a first evacuation conduit; 16-a material outlet of the second rectifying tower; 17-an impurity outlet of the second rectifying tower; 18-a second evacuation conduit; 19-a circulation pump; 20-heating means.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
In the crude m-phenylenediamine raw material used in the embodiment of the invention, the content of m-phenylenediamine is 78-88 wt%, the content of o-phenylenediamine is 10-15 wt%, the content of p-phenylenediamine is 2-5 wt%, the content of light components is 0-0.5 wt%, and the content of heavy components is 0-0.5 wt%.
A method for continuously purifying m-phenylenediamine comprises the following steps:
s1: introducing the crude m-phenylenediamine raw material into a rectifying tower, and removing impurity components in the crude m-phenylenediamine raw material to obtain refined m-phenylenediamine; in the step, the specific method for obtaining the refined m-phenylenediamine comprises the following steps:
s1.1: the method comprises the steps of introducing a crude m-phenylenediamine raw material into a first rectifying tower 10, discharging heavy components (mainly comprising tar or other high-boiling residues) extracted from the first rectifying tower 10 to the outside of a system, wherein the operating pressure of the first rectifying tower 10 is 1-10 KPa (A), the operating temperatures of a tower top and a tower bottom are 135-165 ℃ and 170-200 ℃ respectively, and the content of the m-phenylenediamine rich obtained at the tower top is 85-90 wt%.
S1.2: the light components (mainly comprising p-phenylenediamine, o-phenylenediamine or other low-boiling components) extracted from the second rectifying tower 11 are discharged out of the system, and the refined m-phenylenediamine extracted from the second rectifying tower 11 is obtained. Introducing the rich m-phenylenediamine obtained from the first rectifying tower 10 into a second rectifying tower 11, wherein the operating pressure of the second rectifying tower 11 is 1-10 KPa (A), the operating temperatures of the tower top and the tower bottom are 60-90 ℃ and 170-200 ℃ respectively, and the content of the refined m-phenylenediamine obtained from the tower bottom is 95.0-99.5 wt%.
S2: shunting the obtained refined m-phenylenediamine, and respectively introducing the shunted refined m-phenylenediamine into a first crystallizer 1 and a second crystallizer 2, wherein the first crystallizer 1 and the second crystallizer 2 in the embodiment of the invention are suspension melting crystallizers; the refined m-phenylenediamine is mixed with the solid phase material of the second solid-liquid separator 7 in the first crystallizer 1, the internal temperature is adjusted by a coolant of an external jacket of the first crystallizer 1, and the heat released by the internal crystallization is removed by the coolant of the external jacket of the first crystallizer 1. It is known that m-phenylenediamine is "supercooled" each time it begins to crystallize in the absence of crystals, and it is often necessary to induce its crystallization by bubbling or seeding. Since the solid phase feed from the second solid-liquid separator 7 provides seed crystals for this process, the additional seeding step is eliminated in this step.
The refined m-phenylenediamine is mixed with the slurry of the first solid-liquid separator 3 and the liquid phase of the second solid-liquid separator 7 in the second crystallizer 2, the internal temperature is adjusted by a jacket refrigerant outside the second crystallizer 2, and the heat released by the internal crystallization is removed by the jacket refrigerant outside the second suspension melting crystallizer. It is known that m-phenylenediamine is "supercooled" each time it begins to crystallize in the absence of crystals, and it is often necessary to induce its crystallization by bubbling or seeding. In the prior art, in the static crystallization or falling film crystallization process, because the two crystallization modes are intermittent crystallization modes, the crystallization is induced by adding bubbling or seed crystal and the like into the system in each crystallization period, and the operation is very complicated. In the method of the invention, because the continuous crystallization mode is adopted, only the seed crystal needs to be added in the primary crystallization process, and in the subsequent continuous operation, the crystal in the crystallizer exists in the system and is maintained in dynamic equilibrium, and no additional seed crystal or bubbling is needed. The magma materials obtained by the first crystallizer 1 and the second crystallizer 2 are respectively introduced into a first solid-liquid separator 3 and a second solid-liquid separator 7.
The stirrers in the first crystallizer 1 and the second crystallizer 2 are both provided with wall scraping scrapers, the wall scraping scrapers scrape off thin crystal layers formed in the first crystallizer 1 and the second crystallizer 2, the thin crystal layers are mixed into materials in the first crystallizer 1 and the second crystallizer 2 to form crystal slurry materials, and the crystal slurry materials formed in the first crystallizer 1 and the second crystallizer 2 enter the first solid-liquid separator 3 and the second solid-liquid separator 7 respectively. Scraping the crystal thin layer in the first crystallizer 1 to ensure that the first solid-liquid separator 3 can carry out effective solid-liquid separation, discharging the crystal slurry material from the bottom of the first crystallizer 1 to the first solid-liquid separator 3, separating the crystal slurry material into a solid phase and a liquid phase by a filter screen in the first solid-liquid separator 3, discharging the liquid phase slurry from the upper part of the first solid-liquid separator 3, returning part of the slurry to the first crystallizer 1, and returning the other part of the slurry to the second crystallizer 2; the purpose of scraping off the thin layer of crystals in the second crystallizer 2 is to ensure the solids content of the slurry in the second crystallizer 2, so that no additional seeding and bubbling is required during later operation.
S3: the liquid phase separated by the second solid-liquid separator 7 is circularly led into the second crystallizer 2, and the solid phase separated by the second solid-liquid separator 7 is led into the first crystallizer 1; the slurry from the second crystallizer 2 is separated in the second solid-liquid separator 7, the separated solid-phase material is sent to the first crystallizer 1, a solid-liquid separator with a washing function is selected for improving the purity of the solid phase, and the separated liquid phase is returned to the second crystallizer 2.
And a part of the liquid phase separated by the second solid-liquid separator is circularly led into the second crystallizer, and a part of the liquid phase is led into the first rectifying tower. Wherein the content of m-phenylenediamine in the second suspension melt crystallizer can be changed by adjusting the proportion of the m-phenylenediamine and the m-phenylenediamine, thereby influencing the purity of the solid phase obtained by the second solid-liquid separator. The liquid phase separated by the second solid-liquid separator is introduced into the second crystallizer and introduced into the first rectifying tower in a ratio of 95-90: 5-10.
S4: the liquid phase separated in the first solid-liquid separator is divided and then respectively introduced into a first crystallizer and a second crystallizer; and heating and washing the solid phase separated in the first solid-liquid separator to obtain the m-phenylenediamine product.
In step S4, the steps of heating and washing the solid phase separated in the first solid-liquid separator to obtain m-phenylenediamine product are as follows:
s4.1: the solid phase separated in the first solid-liquid separator forms a crystal bed layer in the first solid-liquid separator, the crystal bed layer is washed and cleaned by circulating washing liquid at the bottom from bottom to top, impurities on the surface of the crystals and between the crystals in the bed layer are replaced by the high-purity washing liquid, and the crystals have a recrystallization process under the action of the hot circulating washing liquid, so that the purity of the crystals is further improved;
s4.2: scraping the recrystallized high-purity crystal bed layer into powder by a scraper in the first solid-liquid separator, mixing the powder into circulating washing liquid, and heating the mixed circulating washing liquid to melt the powder into liquid;
s4.3: and (4) recycling a part of the liquid obtained in the step (S4.2) into the first solid-liquid separator to be continuously used as a recycling washing liquid, and discharging a part of the liquid as a m-phenylenediamine product.
In the step S4.3, the ratio of the liquid used as the circulating washing liquid to the liquid discharged as the m-phenylenediamine product is 30: 1; a purity detection device is arranged on a pipeline for discharging the m-phenylenediamine product, and the m-phenylenediamine product can be discharged to a product collection area after the product detection purity reaches the standard.
The separated solid phase crystals form a crystal bed layer below the first solid-liquid separator 3, and the crystal bed layer in the washing tower is highly purified under the washing of a high-concentration m-phenylenediamine washing solution, wherein the washing solution is a circulating solution of a circulating pump 19 in the washing tower. One path of the circulating liquid obtained by mixing the crystal powder scraped by the scraper and the washing liquid passes through the heating device 20, and then is shunted to the washing tower to be used as the washing circulating liquid, and the other path of the circulating liquid is used as a product output and discharged outside the system. It should be noted that the product can be discharged outside the system after passing the detection, wherein the product purity of more than 99.990% is qualified. And if the product detected purity does not reach the standard, returning to the first crystallizer and/or the second crystallizer, and carrying out crystallization and purification treatment again.
Example one
Based on the above method, in this example, crude m-phenylenediamine 01 having a temperature of 60 ℃ is fed into the first rectifying column 10 at a flow rate of 1500kg/h, wherein the content of m-phenylenediamine in the crude m-phenylenediamine raw material is 84 wt%, the content of o-phenylenediamine is 12.5 wt%, the content of p-phenylenediamine is 3%, the content of light components is 0.5 wt%, and the content of heavy components is 0.5 wt%. The operating pressure of the first rectifying tower 10 is controlled to be 5.5KPa (a), the temperatures of the top and the bottom of the first rectifying tower 10 are controlled to be 150 ℃ and 185 ℃ respectively, and rich m-phenylenediamine with the content of 86 wt% is extracted from the top of the tower and is sent to the second rectifying tower 11. The operating pressure of the second rectifying tower 11 is controlled to be 3.5KPa (a), the temperatures of the top of the second rectifying tower 11 and the bottom of the tower are respectively controlled to be 70 ℃ and 185 ℃, the refined m-phenylenediamine with the content of 99.0wt percent extracted from the top of the tower is completely sent to the first crystallizer 1, and the amount sent to the second crystallizer 2 is zero.
Controlling the temperature of the first crystallizer 1 to be 56 ℃, sending the obtained crystal slurry with the solid content of 30 percent to the first solid-liquid separator 3, washing and melting a solid phase obtained by separation and purification of the first solid-liquid separator 3 into a liquid phase by using a washing solution, and discharging the liquid phase as a product out of the room, wherein the product purity is 99.992 wt%; the liquid phase slurry is separated and purified in the first solid-liquid separator 3, wherein 50 percent of the slurry is returned to the first crystallizer 1, and the rest 50 percent of the slurry is sent to the second crystallizer 2.
In the second crystallizer 2, the slurry 3 from the first solid-liquid separator 3 is mixed with the liquid-phase material from the second solid-liquid separator 7, the temperature of the second crystallizer 2 is controlled to be 51 ℃, the temperature of the second crystallizer 2 is reduced by cooling in a jacket outside the crystallizer, the slurry is crystallized to form a crystal slurry with the solid content of 30%, the crystal slurry is sent to the second solid-liquid separator 7 for separation, the obtained solid-phase material is returned to the first crystallizer 1, the obtained liquid-phase material, wherein 90% of the material is returned to the second crystallizer 2, and 10% of the material is sent to the first rectifying tower 1. The total yield reaches 98.5 percent, and the purity of the obtained m-phenylenediamine product is 99.996 percent.
Example two
The difference from the above-mentioned embodiment is that 50% of the m-phenylenediamine extracted from the top of the second rectifying column 2 is fed to the first crystallizer 1, and 50% is fed to the second crystallizer 2. The purity of the m-phenylenediamine product obtained in the embodiment is 99.980%, and the total yield reaches 98.5%.
EXAMPLE III
The difference from the first embodiment is that the amount of the m-phenylenediamine extracted from the top of the second rectifying tower 2 is zero, and the whole m-phenylenediamine is fed into the second crystallizer 2. The purity of the m-phenylenediamine product obtained in the embodiment is 99.962%, and the total yield reaches 98.5%.
Example four
The difference from the first example is that the liquid phase from the first solid-liquid separator 3, 0% of the slurry, is returned to the first crystallizer 1, and 100% of the slurry is sent to the second crystallizer C2. The purity of the m-phenylenediamine product obtained in the embodiment is 99.994%, and the total yield reaches 98.5%.
EXAMPLE five
The difference from the first embodiment is that in the liquid phase from the second solid-liquid separator 7, 95% of the material is returned to the second crystallizer 2, and 5% of the material is sent to the first rectification column 1. The purity of the m-phenylenediamine product obtained in the embodiment is 99.993%, and the total yield reaches 98.5%.
EXAMPLE six
The difference from the first embodiment is that the temperature, pressure and reflux ratio of the rectifying tower are adjusted so that the content of the refined m-phenylenediamine obtained from the tower bottom of the second rectifying tower 2 is 97%. The purity of the m-phenylenediamine product obtained in the embodiment is 99.990%, and the total yield reaches 98.5%.
EXAMPLE seven
The difference from the first example is that the content of the refined m-phenylenediamine obtained from the bottom of the second rectifying tower 2 is 95%. The purity of the m-phenylenediamine product obtained in the embodiment is 99.961%, and the total yield reaches 98.5%.
Example eight
Based on the method in the first to seventh embodiments, the present invention further provides a system for continuously purifying m-phenylenediamine, as shown in fig. 1, comprising a rectifying tower and a crystallizer, wherein the crystallizer comprises a first crystallizer 1 and a second crystallizer 2, an inlet of the first crystallizer 1 is connected to an outlet of the rectifying tower, an outlet of the first crystallizer 1 is connected to a first solid-liquid separator 3, a feeding pipe of the first solid-liquid separator 3 is used for feeding m-phenylenediamine crystal slurry of the first crystallizer 1, a m-phenylenediamine product discharging pipe 6 is arranged at the bottom of the first solid-liquid separator 3, a liquid phase outlet 4 of the first solid-liquid separator is respectively connected to inlets of the first crystallizer 1 and the second crystallizer 2, and a first solid-liquid outlet 5 is connected to the product discharging pipe 6; an inlet of the second crystallizer 2 is connected with an outlet of the rectifying tower, an outlet of the second crystallizer 2 is connected with a second solid-liquid separator 7, a liquid phase outlet 8 of the second solid-liquid separator is connected with an inlet of the second crystallizer 2, and a solid phase outlet 9 of the second solid-liquid separator is connected with an inlet of the first crystallizer 1.
The first solid-liquid separator 3 is a piston type or hydraulic type washing tower internally provided with a filter screen and a scraper, the washing tower is provided with a circulating pump 19, the outlet of the circulating pump 19 is respectively connected with the feed inlet of the first crystallizer 1 and the feed inlet of the second crystallizer 2, the crystal bed layer of the washing tower is connected with the circulating pump 19, and the crystal bed layer in the washing tower is washed, washed and recrystallized under the action of circulating washing liquid and piston type or hydraulic type pressure filtration to be purified.
The first solid-liquid separator 3 and the second solid-liquid separator 7 are one of the washing tower, the filter or the centrifuge.
The first crystallizer 1 and the second crystallizer 2 are jacket type melt mixing tanks or wall scraping crystallizers with stirring devices.
The rectifying tower comprises a first rectifying tower 10 and a second rectifying tower 11, wherein an inlet of the first rectifying tower 10 is connected with a raw material inlet pipe 12, a material outlet 13 of the first rectifying tower is connected with an inlet of the second rectifying tower 11, and an impurity outlet 14 of the first rectifying tower is connected with a first impurity discharging pipeline 15; a material outlet 16 of the second rectifying tower is respectively connected with the first crystallizer 1 and the second crystallizer 2, and an impurity outlet 17 of the second rectifying tower is connected with a second impurity discharging pipeline 18; the liquid phase outlet 8 of the second solid-liquid separator is also connected with the inlet of the first rectifying tower 10; set up circulating pump 19 between first solid-liquid separator solid phase outlet 5 and the product discharging pipe 6, the export of circulating pump 19 is connected with first solid-liquid separator 3, set up heating device 20 between first solid-liquid separator 3 and the circulating pump 19, the export of circulating pump 19 still is connected with first rectifying column 10 and/or second rectifying column 11.
It should be understood by those skilled in the art that the above embodiments are only for illustrating the present invention and are not to be used as a limitation of the present invention, and that suitable changes and modifications of the above embodiments are within the scope of the claimed invention as long as they are within the spirit and scope of the present invention.
Claims (10)
1. A method for continuously purifying m-phenylenediamine is characterized by comprising the following steps:
s1: introducing the crude m-phenylenediamine raw material into a rectifying tower, and removing impurity components in the crude m-phenylenediamine raw material to obtain refined m-phenylenediamine;
s2: shunting the obtained refined m-phenylenediamine, and respectively introducing the shunted refined m-phenylenediamine into a first crystallizer and a second crystallizer; adding seed crystals or bubbling in the primary crystallization process of the second crystallizer; introducing the crystal slurry materials obtained by the first crystallizer and the second crystallizer into a first solid-liquid separator and a second solid-liquid separator respectively;
s3: the liquid phase separated by the second solid-liquid separator is circularly led into a second crystallizer, and the solid phase separated by the second solid-liquid separator is led into a first crystallizer;
s4: the liquid phase separated in the first solid-liquid separator is divided and then respectively introduced into a first crystallizer and a second crystallizer; and heating and washing the solid phase separated in the first solid-liquid separator to obtain the m-phenylenediamine product.
2. The method for continuously purifying m-phenylenediamine according to claim 1, wherein: in step S4, the steps of heating and washing the solid phase separated in the first solid-liquid separator to obtain m-phenylenediamine product are as follows:
s4.1: forming a crystal bed layer in the first solid-liquid separator from the solid phase separated in the first solid-liquid separator, washing and cleaning the crystal bed layer by circulating washing liquid at the bottom from bottom to top, and recrystallizing crystals under the action of the hot circulating washing liquid while replacing impurities on the surfaces of the crystals and between the crystals in the bed layer by the washing liquid;
s4.2: scraping the recrystallized crystal bed layer into powder by a scraper in the first solid-liquid separator, mixing the powder into circulating washing liquid, and heating the mixed circulating washing liquid to melt the powder into liquid;
s4.3: and (4) recycling a part of the liquid obtained in the step (S4.2) into the first solid-liquid separator to be continuously used as a recycling washing liquid, and discharging a part of the liquid as a m-phenylenediamine product.
3. The method for continuously purifying m-phenylenediamine according to claim 2, wherein: in step S4.3, the ratio of the liquid used as the recycle wash liquid to the liquid discharged as the m-phenylenediamine product is 30: 1; a purity detection device is arranged on a pipeline for discharging the m-phenylenediamine product, and the m-phenylenediamine product can be discharged to a product collection area after the product detection purity reaches the standard.
4. The method for continuously purifying m-phenylenediamine according to claim 3, wherein: and if the product detected purity does not reach the standard, returning to the first crystallizer and/or the second crystallizer.
5. The method for continuously purifying m-phenylenediamine according to claim 1, wherein: the specific steps of obtaining the m-phenylenediamine in the step S1 are as follows:
s1.1: introducing a crude m-phenylenediamine raw material into a first rectifying tower, discharging heavy components extracted by the first rectifying tower to the outside of a system, and introducing m-phenylenediamine-rich obtained by the first rectifying tower into a second rectifying tower;
s1.2: and discharging the light components extracted by the second rectifying tower to the outside of the system to obtain the refined m-phenylenediamine extracted by the second rectifying tower.
6. The method for continuously purifying m-phenylenediamine according to claim 5, wherein: in step S3, a part of the liquid phase separated by the second solid-liquid separator is circulated and introduced into the second crystallizer, and a part of the liquid phase is introduced into the first rectifying tower.
7. The method for continuously purifying m-phenylenediamine according to claim 6, wherein: the liquid phase separated by the second solid-liquid separator is introduced into the second crystallizer and introduced into the first rectifying tower in a ratio of 95-90: 5-10.
8. The method for continuously purifying m-phenylenediamine according to claim 1, wherein: in step S2, the stirrers in the first crystallizer and the second crystallizer are both provided with wall scraping scrapers, the wall scraping scrapers scrape off thin crystal layers formed in the first crystallizer and the second crystallizer, the thin crystal layers are mixed into materials in the first crystallizer and the second crystallizer to form crystal slurry materials, and the crystal slurry materials formed in the first crystallizer and the second crystallizer enter the first solid-liquid separator and the second solid-liquid separator respectively.
9. A system for continuously purifying m-phenylenediamine comprises a rectifying tower and a crystallizer, and is characterized in that: the crystallizer comprises a first crystallizer (1) and a second crystallizer (2), an inlet of the first crystallizer (1) is connected with an outlet of the rectifying tower, an outlet of the first crystallizer (1) is connected with a first solid-liquid separator (3), a liquid phase outlet (4) of the first solid-liquid separator is respectively connected with inlets of the first crystallizer (1) and the second crystallizer (2), and a solid phase outlet (5) of the first solid-liquid separator is connected with a product discharge pipe (6); the inlet of the second crystallizer (2) is connected with the outlet of the rectifying tower, the outlet of the second crystallizer (2) is connected with a second solid-liquid separator (7), the liquid phase outlet (8) of the second solid-liquid separator is connected with the inlet of the second crystallizer (2), and the solid phase outlet (9) of the second solid-liquid separator is connected with the inlet of the first crystallizer (1).
10. The system for continuously purifying m-phenylenediamine according to claim 9, wherein: the rectifying tower comprises a first rectifying tower (10) and a second rectifying tower (11), an inlet of the first rectifying tower (10) is connected with a raw material inlet pipe (12), a material outlet (13) of the first rectifying tower is connected with an inlet of the second rectifying tower (11), and an impurity outlet (14) of the first rectifying tower is connected with a first impurity discharging pipeline (15); a material outlet (16) of the second rectifying tower is respectively connected with the first crystallizer (1) and the second crystallizer (2), and an impurity outlet (17) of the second rectifying tower is connected with a second impurity discharging pipeline (18); the liquid phase outlet (8) of the second solid-liquid separator is also connected with the inlet of the first rectifying tower (10); set up circulating pump (19) between first solid-liquid separator solid phase outlet (5) and product discharging pipe (6), the export and first solid-liquid separator (3) of circulating pump (19) are connected, set up heating device (20) between first solid-liquid separator (3) and circulating pump (19), the export of circulating pump (19) still is connected with first rectifying column (10) and/or second rectifying column (11).
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| CN202111133994.0A CN113735718A (en) | 2021-09-27 | 2021-09-27 | Method and system for continuously purifying m-phenylenediamine |
| CN202211116953.5A CN115490599B (en) | 2021-09-27 | 2022-09-14 | Method and system for continuously purifying m-phenylenediamine |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114249658A (en) * | 2021-12-23 | 2022-03-29 | 四川北方红光特种化工有限公司 | Method for preparing polymerization-grade m-phenylenediamine through melt crystallization and recycling mother liquor |
| CN114425287A (en) * | 2022-01-28 | 2022-05-03 | 山东海成石化工程设计有限公司 | System and method for producing succinic anhydride by using maleic anhydride as raw material |
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| NL125644C (en) * | 1961-05-22 | |||
| BE631132A (en) * | 1965-05-17 | |||
| US3862234A (en) * | 1973-06-12 | 1975-01-21 | Jefferson Chem Co Inc | Amine recovery |
| FR2623801B1 (en) * | 1987-11-30 | 1990-04-20 | Rhone Poulenc Chimie | PROCESS FOR THE PURIFICATION OF HEXAMETHYLENEDIAMINE |
| CN101250113B (en) * | 2008-03-28 | 2010-09-29 | 浙江鸿盛化工有限公司 | Method for refining p-phenylene diamine |
| WO2010093203A2 (en) * | 2009-02-12 | 2010-08-19 | 주식회사 엘지화학 | Dividing wall distillation column |
| KR101146034B1 (en) * | 2012-02-14 | 2012-05-15 | 한모기술주식회사 | The purification method for para-phenylenediamine |
| CN103665035B (en) * | 2013-12-11 | 2016-08-17 | 鹤壁市农林制药有限公司 | A kind of processing method of glyphosate mother solution |
| CN104788321B (en) * | 2015-04-22 | 2017-03-22 | 江苏金凯树脂化工有限公司 | Recycling device and recycling technology of dimethylamine |
| CN106560464A (en) * | 2016-10-31 | 2017-04-12 | 上海科富恺机械设备有限公司 | Separation system and separation method for separating mixed dichlorobenzene |
| CN107286023B (en) * | 2017-06-06 | 2018-07-20 | 青岛科技大学 | A kind of purification process of m-phenylene diamine (MPD) |
| CN107325003A (en) * | 2017-08-01 | 2017-11-07 | 安徽东至广信农化有限公司 | A kind of method that Liquid-phase Hydrogenation Process synthesizes o-chloraniline |
| CN109879762B (en) * | 2019-03-27 | 2022-02-22 | 宁夏瑞泰科技股份有限公司 | Purification method of o-phenylenediamine |
| CN110437074A (en) * | 2019-08-16 | 2019-11-12 | 上海鸿源鑫创材料科技有限公司 | A kind of process for producing of m-phenylene diamine (MPD) |
| CN110746276B (en) * | 2019-12-05 | 2022-08-02 | 万华化学集团股份有限公司 | Method for producing o-tert-butylphenol and p-tert-butylphenol by rectification and crystallization |
-
2021
- 2021-09-27 CN CN202111133994.0A patent/CN113735718A/en not_active Withdrawn
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114249658A (en) * | 2021-12-23 | 2022-03-29 | 四川北方红光特种化工有限公司 | Method for preparing polymerization-grade m-phenylenediamine through melt crystallization and recycling mother liquor |
| CN114425287A (en) * | 2022-01-28 | 2022-05-03 | 山东海成石化工程设计有限公司 | System and method for producing succinic anhydride by using maleic anhydride as raw material |
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| CN115490599A (en) | 2022-12-20 |
| CN115490599B (en) | 2023-12-26 |
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