CN217527429U - System for high-efficient separation caprolactam - Google Patents
System for high-efficient separation caprolactam Download PDFInfo
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- CN217527429U CN217527429U CN202221338207.6U CN202221338207U CN217527429U CN 217527429 U CN217527429 U CN 217527429U CN 202221338207 U CN202221338207 U CN 202221338207U CN 217527429 U CN217527429 U CN 217527429U
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Abstract
A high-efficiency caprolactam separation system consists of a mixing reactor and a reaction evaporation crystallizer, wherein the mixing reactor is connected with the reaction evaporation crystallizer; in the mixing reactor, the Beckmann rearranged translocated ester is mixed with a sulfate solution in the mixing reactor to generate a mixed liquid, and the mixed liquid is concentrated by evaporation in the mixing reactor to separate an acid sulfate or a mixture of the acid salt and the sulfate and an aqueous caprolactam phase layer; in the reactive evaporative crystallizer, the aqueous caprolactam phase layer is neutralized with ammonia or alkali to produce caprolactam and sulfate. In the process of removing caprolactam, sulfate is used as an additive, and the sulfate reacts with rearranged transposition ester hydrolysis ions to realize the preparation of caprolactam by cyclohexanone oxime Beckmann rearrangement, reduce the consumption of ammonia or alkali by more than 40 percent and achieve the aim of separating caprolactam; the system is simpler.
Description
Technical Field
The utility model relates to a system for high-efficient separation caprolactam.
Background
Caprolactam has a molecular formula of C6H11NO, a molecular weight of 113.16, white crystal at normal temperature and a melting point of 69.3 ℃, is an important chemical product and is widely applied to manufacturing chinlon and engineering plastics. The preparation method of caprolactam is more, and the preparation of caprolactam by Beckmann rearrangement of cyclohexanone oxime is one of the most industrialized methods at present. At present, 90% of devices in the world adopt concentrated sulfuric acid or fuming sulfuric acid as cyclohexanone oxime of a catalyst to carry out the Beckmann rearrangement process, and although the selectivity of the process is high, the process takes ammonia as a neutralization reaction raw material to generate a large amount of ammonium sulfate with low added value. Under the circumstances, domestic and foreign enterprises have been dedicated to develop a low-sulfur ammonium rearrangement process and a sulfur acid-free by-product process, BASF has developed a process using phosphoric acid as a catalyst, lnwenta has performed a rearrangement reaction using acetic acid and acetic anhydride as a mixed catalyst in the presence of an ion exchange resin, and then has removed caprolactam with cold water without a step of neutralizing ammonia, DSM has successively developed an ionic liquid catalytic system and beckmann rearrangement under supercritical conditions at home and abroad with a solid acid as a catalyst, under the precondition of advocating "atomic economy" and "environmental economy", but various new technologies and new processes have different advantages and disadvantages.
Under the condition, the utility model discloses greatly reduce and carry out beckmann rearrangement with concentrated sulfuric acid or oleum as the cyclohexanone oxime of catalyst and prepare accessory product ammonium sulfate in the caprolactam technology and produce, very big improvement caprolactam production efficiency, reduced caprolactam manufacturing cost.
Disclosure of Invention
The utility model aims at providing a system of high-efficient separation caprolactam can make beckmann rearrangement back, acquires the in-process of caprolactam, reduces ammonia or alkali quantity more than 40%, and only produces a small amount of ammonium sulfate, very big reduction manufacturing cost.
The technical scheme for realizing the aim of the utility model is that a caprolactam separation system consists of a mixing reactor and a reaction evaporation crystallizer, wherein the mixing reactor is connected with the reaction evaporation crystallizer;
in the mixing reactor, the Beckmann rearranged translocated ester and the sulfate solution are mixed in the mixing reactor to generate a mixed liquid, and the mixed liquid is evaporated in the mixing reactor to separate out an acid sulfate (or a mixture of the acid salt and the sulfate) and an aqueous caprolactam phase layer;
in the reactive evaporative crystallizer, caprolactam and sulfate are separated by the neutralization reaction of the aqueous caprolactam phase layer and ammonia or alkali.
The utility model has the advantages of, 1) adopt the sulfate as the material of hydrolysising of sulphuric acid transposition ester, make transposition ester after hydrolysising, produce ionic reaction again, because the basicity of sulfate is stronger than the transposition ester after hydrolysising, after external condition changes appearing, sulfate radical after the hydrolysis is preferred to be combined with the sulfate, generate the acid sulfate, the acid sulfate is separated out through the crystallization, make the constraint of sulfate radical to caprolactam in the transposition ester weaken, the hydrous caprolactam on upper portion shifts out the caprolactam system in ammonia or alkali neutralization reaction, because the sulfate is when sulfuric acid concentration is more than or equal to 35%, can generally generate the acid sulfate after the crystallization, use ammonia or alkali to participate in neutralization reaction volume and descend by a wide margin, generally reach more than 40%.
2) The acid sulfate is extracted and converted into sulfate and sulfuric acid, the extraction liquid containing sulfuric acid is distilled to separate the extracting agent and the sulfuric acid, the sulfuric acid can be concentrated and refined for being reused in Beckmann rearrangement, and the sulfate is reused as the transposition ester hydrolysis material, so that the cyclic utilization is realized to the maximum extent.
Drawings
FIG. 1 is a schematic diagram of a process for separating caprolactam.
FIG. 2 is a preferred block diagram of a caprolactam separation process.
FIG. 3 is a schematic diagram of the caprolactam separation system of FIG. 2.
As shown in the figure, a mixing reactor 1, a neutralization reaction evaporative crystallizer 2.
Detailed Description
An additive for efficiently separating caprolactam is a sulfate solution; the Beckmann rearranged translocated ester is mixed with a sulfate solution. Preferably, the ratio of the number of sulfate groups of the translocation ester to the number of sulfate groups of the sulfate solution is 1:1.5-0.1, generally the amount theoretically calculated.
Further preferably, the sulfate solution (generally, the sulfate solution is a solution of sulfate and water) is one or a combination of any several of ammonium sulfate, sodium sulfate, potassium sulfate and ferrous sulfate;
or one of ammonium sulfate, sodium sulfate, potassium sulfate and ferrous sulfate and one or any combination of copper sulfate, aluminum potassium sulfate, aluminum sulfate, cadmium sulfate, zinc sulfate and magnesium sulfate;
or any combination of ammonium sulfate, sodium sulfate, potassium sulfate and ferrous sulfate and one or any combination of copper sulfate, aluminum potassium sulfate, aluminum sulfate, cadmium sulfate, zinc sulfate and magnesium sulfate.
Preferably, the Beckmann rearranged translocated ester is mixed with a sulfate solution at a temperature of 10-130 ℃.
As shown in FIG. 1, a caprolactam separation method comprises mixing, separating, neutralizing and further comprises subsequent treatment;
said mixing, the beckmann rearranged translocated ester is mixed with a sulfate solution to form a mixed solution, preferably, the sulfate of said translocated ester is mixed with the sulfate solution in a ratio of 1:1.5-0.1;
separating, enriching the mixed solution in an evaporation and concentration mode, separating caprolactam, and in the normal pressure or negative pressure and single-effect or multi-effect evaporation process, when the quantitative ratio of sulfate radicals to the solvent in the solution is more than or equal to 1:4, forming an aqueous caprolactam phase layer on the upper liquid level, and preparing an acid sulfate precipitation solution on the lower liquid level, preferably, separating caprolactam from the mixed solution in an evaporation mode, wherein the evaporation temperature is 30-130 ℃;
and (3) the aqueous caprolactam phase layer is input into a neutralization reaction evaporation crystallizer to be neutralized with ammonia or alkali, alkali or ammonia is added, the PH is 3-7, the evaporation temperature is 45-120 ℃, sulfate is crystallized from the bottom of the crystallizer, and the upper part is the product of crude caprolactam.
Preferably, as shown in fig. 2, in the subsequent treatment, the acid sulfate is subsequently extracted by using a 10.
As shown in figure 3, a caprolactam separation system consists of a mixing reactor 1 and a reactive evaporative crystallizer 2, wherein the mixing reactor 1 is connected with the reactive evaporative crystallizer 2;
in the mixing reactor 1, the Beckmann rearranged translocated ester is mixed with a sulfate solution in the mixing reactor to generate a mixed liquid, and the mixed liquid is concentrated by evaporation in the mixing reactor 1 to separate an acid sulfate and an aqueous caprolactam phase layer;
in the reactive evaporation crystallizer, the aqueous caprolactam phase layer and ammonia or alkali are subjected to neutralization reaction to separate caprolactam and sulfate;
the acid sulfate is centrifuged by a thick crystallizing device and a centrifuge, the acid sulfate is extracted and separated to obtain sulfate crystals, the mother liquor is distilled under normal pressure or negative pressure, the gas phase is condensed to recover alcohol, and the liquid phase is used for obtaining sulfuric acid solution.
Example one, ammonium sulfate was formulated with water as a 45-48% strength solution and mixed in a mixing reactor 1 with a beckmann rearranged translocated ester whose sulfate to sulfate salt solution ratio was 1:1.5-0.1.
The mixing reactor 1 is a two-effect negative pressure evaporator, and is heated by 1.2kgf/cm2 low pressure steam hot water, the one-effect evaporation temperature is 80-85 deg.C, the absolute evaporation pressure is 0.5-0.6, the two-effect evaporation temperature is 60-65 deg.C, and the evaporation pressure is 0.2-0.3kgf/cm2. Feeding the transposition ester by 85-105kg per hour, feeding the ammonium sulfate solution by 240-265kg per hour, evaporating the water by 150-190kg, evaporating to separate out the acid sulfate at the bottom and the supernatant (aqueous caprolactam phase layer), extracting the acid sulfate solid by using 3-4 times of methanol and water mixed solution of crystals in the next working procedure, wherein the ratio of methanol to water is 4; the supernatant (aqueous caprolactam phase layer) enters the reactive evaporative crystallizer 2.
Extracting and separating the mixed solution of methanol and water to obtain ammonium sulfate and mother liquor, distilling the mother liquor (removing the extractant by absolute pressure of 0.5-0.6 kgf/cm < 2 >) to separate gas-phase methanol, water vapor and liquid-phase sulfuric acid (10-50% sulfuric acid solution), dissolving ammonium sulfate crystals in water, and returning the dissolved ammonium sulfate crystals to the mixing reactor 1.
Adding ammonia gas into the neutralization reaction evaporator 2, wherein the pH value is 3.5-6.5, the evaporation temperature is 45-120 ℃, the evaporation process can be normal pressure or pressure evaporation dehydration, the upper layer liquid forms crude caprolactam liquid, the crude caprolactam liquid is discharged out of the system, and ammonium sulfate crystals are formed at the bottom. Discharging the ammonium sulfate crystals from the bottom, and feeding the ammonium sulfate crystals into a centrifuge to obtain ammonium sulfate.
Example two potassium sulfate was formulated with water as a 40-50% strength solution and mixed in mixing reactor 1 with a beckmann rearranged translocated ester having a sulfate to sulfate ratio of the sulfate solution of 1:1.5-0.2.
The mixing reactor 1 is a two-effect negative pressure evaporator, and is heated by 1.2kgf/cm2 low pressure steam hot water at a first-effect evaporation temperature of 73-78 deg.C, an absolute evaporation pressure of 0.4-0.6 kgf/cm2, a second-effect evaporation temperature of 60-65 deg.C, and an evaporation pressure of 0.2-0.3kgf/cm2. Feeding the transposition ester by 85-105kg per hour, feeding the potassium sulfate solution by 225-260kg per hour, evaporating the water by 150-190kg, evaporating to separate out the acid sulfate at the bottom and the supernatant (aqueous caprolactam phase layer), extracting the acid sulfate solid by using 3-4 times of methanol and water mixed solution of a crystal in the next working procedure, wherein the ratio of methanol to water is 4; the supernatant (aqueous caprolactam phase layer) enters the reactive evaporative crystallizer 2.
The mixed solution of methanol and water is extracted and separated to obtain potassium sulfate and mother liquor, the mother liquor is distilled (the extractant is removed by absolute pressure of 0.5-0.6 kgf/cm < 2 >) to separate gas-phase methanol, water vapor and liquid-phase sulfuric acid (10-50% sulfuric acid solution), and potassium sulfate crystals are added with water to be dissolved and then returned to the mixing reactor 1.
Adding ammonia gas into the neutralization reaction evaporator 2, wherein the pH value is 3.5-6.5, the evaporation temperature is 45-120 ℃, the evaporation process can be normal pressure or pressure evaporation dehydration, the upper layer liquid forms crude caprolactam liquid, the crude caprolactam liquid is discharged out of the system, and potassium sulfate crystals are formed at the bottom. Discharging potassium sulfate crystals from the bottom, and feeding the potassium sulfate crystals into a centrifuge to obtain potassium sulfate.
Example three, sodium sulfate was formulated with water into a 40-50% strength solution and mixed in mixing reactor 1 with a beckmann rearranged translocated ester whose sulfate to sulfate salt solution ratio was 1:1.5-0.1.
The mixing reactor 1 is a two-effect negative pressure evaporator, and is heated by 1.2kgf/cm2 low pressure steam hot water at a first-effect evaporation temperature of 73-78 deg.C, an absolute evaporation pressure of 0.4-0.6 kgf/cm2, a second-effect evaporation temperature of 60-65 deg.C, and an evaporation pressure of 0.2-0.3kgf/cm2. Feeding the transposition ester by 85-105kg per hour, feeding the sodium sulfate solution by 240-270kg per hour, evaporating the water by 150-190kg, evaporating to separate out acid sulfate at the bottom and a supernatant (containing a caprolactam phase layer), extracting the acid sulfate solid by using a mixed solution of 3-4 times of methanol and water of a crystal in the next working procedure, wherein the ratio of the methanol to the water is 4; the supernatant (aqueous caprolactam phase layer) enters the reactive evaporative crystallizer 2.
Extracting and separating the mixed solution of methanol and water to obtain sodium sulfate and mother liquor, distilling the mother liquor in the working procedure (extracting agent removal is carried out under the absolute pressure of 0.5-0.6 kgf/cm < 2 >) to separate gas-phase methanol, water vapor and liquid-phase sulfuric acid (10-50% sulfuric acid solution), and adding water to dissolve sodium sulfate crystals and returning the sodium sulfate crystals to the mixing reactor 1.
Adding ammonia gas into the neutralization reaction evaporator 2, wherein the pH is 3.5-6.5, the evaporation temperature is 45-120 ℃, the evaporation process can be normal pressure or pressurized evaporation dehydration, the upper layer liquid forms crude caprolactam liquid, the crude caprolactam liquid is discharged out of the system, and sodium sulfate crystals are formed at the bottom. And discharging the sodium sulfate crystals from the bottom and feeding the sodium sulfate crystals into a centrifuge to obtain sodium sulfate.
Example four, ferrous sulfate was formulated with water into a 35-50% strength solution and mixed in a mixing reactor 1 with a beckmann rearranged translocated ester whose sulfate to sulfate salt solution ratio was 1:1.5-0.4.
The mixing reactor 1 is a two-effect negative pressure evaporator, and is heated by 1.2kgf/cm2 low pressure steam hot water, the one-effect evaporation temperature is 70-80 deg.C, the absolute evaporation pressure is 0.3-0.6 kgf/cm2, the two-effect evaporation temperature is 60-65 deg.C, and the evaporation pressure is 0.1-0.4kgf/cm2. Feeding the transposition ester by 75-115kg per hour, feeding the ferrous sulfate solution by 230-275kg per hour, evaporating the water by 140-193kg, evaporating to separate out the acid sulfate at the bottom and the supernatant (aqueous caprolactam phase layer), extracting the acid sulfate solid by using 3-4 times of methanol and water mixed solution of the acid sulfate solid and a crystal in the next working procedure, wherein the ratio of the methanol to the water is 4; the supernatant (aqueous caprolactam phase layer) enters the reactive evaporative crystallizer 2.
Extracting and separating the mixed solution of methanol and water to obtain ferrous sulfate and mother liquor, separating gas-phase methanol, water vapor and liquid-phase sulfuric acid (10-50% sulfuric acid solution) from the mother liquor in a process distillation (removing an extracting agent under the absolute pressure of 0.5-0.6 kgf/cm & lt 2 & gt), and adding water to dissolve ferrous sulfate crystals and returning the dissolved ferrous sulfate crystals to the mixing reactor 1.
Adding ammonia gas into the neutralization reaction evaporator 2, wherein the PH is 3.5-6.5, the evaporation temperature is 45-120 ℃, the evaporation process can be normal pressure or pressure evaporation dehydration, the upper layer liquid forms crude caprolactam liquid, the crude caprolactam liquid is discharged out of the system, and ferrous sulfate crystals are formed at the bottom. Ferrous sulfate crystals are discharged from the bottom and enter a centrifuge to obtain ferrous sulfate.
In example five, ammonium sulfate and magnesium sulfate are prepared into a solution with the concentration of 40-48% by using water, and are mixed with Beckmann rearranged transposition ester in a mixing reactor 1 to generate hydrolysis reaction, and the sulfate radical of the transposition ester and the sulfate radical of the sulfate salt solution have the quantity ratio of 1:1.5-0.6.
The mixing reactor 1 is a double-effect negative pressure evaporator, and is heated by 1.0-1.3kgf/cm2 low pressure steam hot water at a first-effect evaporation temperature of 75-85 deg.C and an evaporation absolute pressure of 0.5-0.6, and the double-effect evaporation temperature is controlled at 54-65 deg.C and an evaporation pressure of 0.2-0.3kgf/cm2. Feeding the transposition ester by 65-125kg per hour, feeding the ammonium sulfate solution by 210-255kg per hour, evaporating the water by 150-190kg, evaporating to separate out the acid sulfate at the bottom and the supernatant (aqueous caprolactam phase layer), extracting the acid sulfate solid by using 3-4 times of methanol and water mixed solution of crystals in the next working procedure, wherein the ratio of methanol to water is 4; the supernatant (aqueous caprolactam phase layer) enters the reactive evaporative crystallizer 2.
Extracting and separating the mixed solution of methanol and water to obtain ammonium sulfate, magnesium sulfate and mother liquor, distilling the mother liquor in the working procedure (extracting agent removal is carried out under the absolute pressure of 0.5-0.6 kgf/cm < 2 >), separating gas phase methanol, water vapor and liquid phase sulfuric acid (10-50% sulfuric acid solution), adding water into ammonium sulfate and magnesium sulfate crystals for dissolving, and returning the ammonium sulfate and magnesium sulfate crystals to the mixing reactor 1.
Adding ammonia gas into the neutralization reaction evaporator 2, wherein the pH is 3.0-6.5, the evaporation temperature is 35-120 ℃, the evaporation process can be normal pressure or pressure evaporation dehydration, the upper layer liquid forms crude caprolactam liquid, the crude caprolactam liquid is discharged out of the system, and ammonium sulfate and magnesium sulfate crystals are formed at the bottom. Discharging ammonium sulfate and magnesium sulfate crystals from the bottom, and feeding the ammonium sulfate and magnesium sulfate crystals into a centrifuge to obtain ammonium sulfate and magnesium sulfate.
Example six, ammonium sulfate, potassium aluminum sulfate, magnesium sulfate were formulated with water into 35-50% strength solutions and mixed in mixing reactor 1 with beckmann rearranged translocated ester with sulfate to sulfate ratio of the sulfate solution 1:1.5-0.5.
The mixing reactor 1 is a two-effect negative pressure evaporator, and is heated by 1.2kgf/cm2 low pressure steam hot water, the one-effect evaporation temperature is 70-80 deg.C, the absolute evaporation pressure is 0.3-0.6 kgf/cm2, the two-effect evaporation temperature is 60-65 deg.C, and the evaporation pressure is 0.1-0.4kgf/cm2. Feeding the transposition ester by 75-115kg per hour, feeding ammonium sulfate, aluminum potassium sulfate and magnesium sulfate solution by 230-275kg per hour, evaporating water by 140-193kg, evaporating to separate out acid sulfate at the bottom and supernatant (aqueous caprolactam phase layer), extracting the acid sulfate solid by using 3-4 times of methanol and water mixed solution of crystals in the next working procedure, wherein the ratio of methanol to water is 4; the supernatant (aqueous caprolactam phase layer) enters the reactive evaporative crystallizer 2.
Extracting and separating the mixed solution of methanol and water to obtain ammonium sulfate, aluminum potassium sulfate, magnesium sulfate and mother liquor, distilling the mother liquor in the working procedure (extracting agent removal is carried out under the absolute pressure of 0.5-0.6 kgf/cm & lt 2 & gt) to separate gas-phase methanol, water vapor and liquid-phase sulfuric acid (10-50% sulfuric acid solution), adding water to dissolve ammonium sulfate, aluminum potassium sulfate and magnesium sulfate crystals, and returning the crystals to the mixing reactor 1.
Adding ammonia gas into the neutralization reaction evaporator 2, wherein the PH is 4-6.5, the evaporation temperature is 45-120 ℃, the evaporation process can be normal pressure or pressure evaporation dehydration, the upper layer liquid forms crude caprolactam liquid, the crude caprolactam liquid is discharged out of the system, and ammonium sulfate, aluminum potassium sulfate and magnesium sulfate crystals are formed at the bottom. Discharging ammonium sulfate, aluminum potassium sulfate and magnesium sulfate crystals from the bottom, and feeding the crystals into a centrifuge to obtain the ammonium sulfate, the aluminum potassium sulfate and the magnesium sulfate.
Comparing the above examples with the prior art, even if the trans-site ester is directly neutralized with ammonia or alkali to extract caprolactam, the above six examples reduce the amount of ammonia (or alkali) by at least 40%, and some examples reach more than 60%.
The six embodiments are only partial embodiments, and the purpose of the present invention can be achieved as long as the sulfate contains ammonium sulfate, sodium sulfate, potassium sulfate and ferrous sulfate, and the ammonium sulfate, sodium sulfate, potassium sulfate and ferrous sulfate account for more than 10% of any one of the sulfate.
Claims (1)
1. A caprolactam separation system is characterized in that: the system consists of a mixing reactor and a reaction evaporation crystallizer, wherein the mixing reactor is connected with the reaction evaporation crystallizer;
in the mixing reactor, the Beckmann rearranged transposition ester and a sulfate solution are mixed in the mixing reactor to generate a mixed liquid, and the mixed liquid is concentrated and separated out an acid sulfate or a mixture of the acid salt and the sulfate and an aqueous caprolactam phase layer in the mixing reactor through evaporation;
in the reactive evaporative crystallizer, the aqueous caprolactam phase layer is neutralized with ammonia or alkali to generate caprolactam and sulfate.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114907265A (en) * | 2022-01-28 | 2022-08-16 | 陕西科原环保节能科技有限公司 | Additive for efficiently separating caprolactam, and caprolactam separation method and system |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114907265A (en) * | 2022-01-28 | 2022-08-16 | 陕西科原环保节能科技有限公司 | Additive for efficiently separating caprolactam, and caprolactam separation method and system |
| CN114907265B (en) * | 2022-01-28 | 2023-10-20 | 陕西科原环保节能科技有限公司 | Additive for efficiently separating caprolactam and caprolactam separation method and system |
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