Residual liquid treatment system in synthesis process of diethyl methylphosphite

Abstract

The utility model discloses a residual liquid treatment system in a synthesis process of diethyl methylphosphite, which belongs to the technical field of residual liquid treatment in production of diethyl methylphosphite and comprises a hydrolysis reactor, a reduced pressure distillation device I and a reduced pressure distillation device II which are connected in sequence, and an inlet of the hydrolysis reactor is connected with a residual liquid outlet of a rectifying tower. An ethanol extraction pipeline is arranged above the reduced pressure distillation device I, the reduced pressure distillation device II is provided with a methyl monoethyl phosphite extraction pipeline and a diethyl phosphite pipeline, the hydrolysis reactor is connected with a nitrogen replacement pipeline and a deionized water supply pipeline, and a jacket filled with a heat exchange medium is arranged outside the hydrolysis reactor. A temperature sensor I is arranged on the hydrolysis reactor, a pressure sensor I is arranged on the reduced pressure distillation device I, and a pressure sensor II is arranged on the reduced pressure distillation device II, so that the problems of high treatment cost and high treatment difficulty of the raffinate after rectification in the production of diethyl methylphosphite and waste of phosphorus in the prior art are solved.

Description

Technical Field

[0001] The utility model belongs to the technical field of residual liquid treatment in the production of diethyl methyl phosphite, and specifically relates to a residual liquid treatment system in the synthesis process of diethyl methyl phosphite. Background Art

[0002] Diethyl methyl phosphite is an important intermediate in the production of glufosinate or some phosphorus-based flame retardants. At present, the commonly used diethyl methyl phosphite in China is obtained by esterification and distillation of methyl phosphorus dichloride. Since methyl phosphorus dichloride generally contains 2% to 5% of phosphorus trichloride and there are some side reactions during the esterification reaction, the main components of the residual liquid after distillation are triethyl phosphite, diethyl phosphite, and monoethyl methyl phosphite, and a small amount of diethyl methyl phosphite. Because the boiling points of each component are close, it is extremely difficult to directly distill and separate the four components of this part of the residual liquid, and it is difficult to treat it as waste liquid, and the phosphorus element in it is wasted.

[0003] Based on the above production status, the residual liquid is considered to be further utilized as a resource. After being treated by a specific system, the phosphorus and other elements in the residual liquid are recycled as much as possible to reduce the external discharge of phosphorus and other elements and reduce the cost of residual liquid treatment. Utility Model Content

[0004] The utility model aims to solve the problems in the prior art of high cost and difficulty in treating residual liquid after distillation and waste of phosphorus element in the production of diethyl methyl phosphite synthesized by using methyl phosphorus dichloride.

[0005] In order to achieve the above-mentioned invention object, the technical solution of the utility model is as follows:

[0006] A residual liquid treatment system in the synthesis process of diethyl methyl phosphite comprises a hydrolysis reactor, a vacuum distillation device I and a vacuum distillation device II, wherein the inlet of the hydrolysis reactor is connected to the residual liquid outlet of a distillation tower, the liquid outlet of the hydrolysis reactor is connected to the feed port I of the vacuum distillation device I, an ethanol extraction pipeline is arranged above the vacuum distillation device I, the discharge port I of the vacuum distillation device I is connected to the feed port II of the vacuum distillation device II, and the vacuum distillation device II is provided with a monoethyl methyl phosphite extraction pipeline and a diethyl phosphite pipeline.

[0007] The hydrolysis reactor is connected with a nitrogen replacement pipeline and a deionized water supply pipeline, a jacket with a heat exchange medium passing therethrough is arranged outside the hydrolysis reactor, a temperature sensor I is arranged on the hydrolysis reactor, a pressure sensor I is arranged on the vacuum distillation device I, and a pressure sensor II is arranged on the vacuum distillation device II.

[0008] Furthermore, the jacket is connected with a heat exchange medium inlet pipe and a heat exchange medium discharge pipe, and the heat exchange medium inlet pipe is provided with a temperature sensor II, a flow meter, and a valve I.

[0009] Furthermore, the valve I is respectively connected to the temperature sensor II and the flow meter for control.

[0010] Furthermore, the vacuum distillation apparatus I is provided with a temperature sensor III.

[0011] Furthermore, the vacuum distillation apparatus II is provided with a temperature sensor IV.

[0012] Furthermore, the hydrolysis reactor is provided with a stirring mechanism.

[0013] Furthermore, the vacuum distillation apparatus I is a thin film evaporator.

[0014] Furthermore, the vacuum distillation device II is a distillation tower I.

[0015] Furthermore, an intermediate tank I is provided between the distillation tower and the hydrolysis reactor; and an intermediate tank II is provided between the vacuum distillation device I and the vacuum distillation device II.

[0016] Beneficial effects of the utility model:

[0017] 1. In the utility model, the residual liquid after distillation in the production of diethyl methyl phosphite synthesized by methyl phosphorus dichloride can be separated into relatively pure monoethyl methyl phosphite (content reaches 99% (A%, GC)) and diethyl phosphite (content can reach 98.5% (A%, GC)) after passing through the treatment system of this scheme. Among them, monoethyl methyl phosphite can be recycled as a raw material for glufosinate or some flame retardants, and diethyl phosphite can be recycled as a raw material for various pesticides and plant growth regulators, thereby realizing the recycling of phosphorus, reducing the pressure of waste liquid treatment, and reducing the damage to the environment.

[0018] 2. In the utility model, a two-stage vacuum distillation device is designed to process the material in sections. At the same time, the pressure in the vacuum distillation device I and the vacuum distillation device II are monitored respectively by pressure sensor I and pressure sensor II, which can effectively control the pressure within the expected range and ensure the separation effect.

[0019] 3. In the utility model, a jacket with a heat exchange medium is used to heat up, cool down and insulate the hydrolysis reactor, so that the hydrolysis reactor is kept within a certain stable temperature range, the hydrolysis efficiency is improved, and such a heat exchange medium is conducive to the recovery and utilization of heat. In this scheme, the material processing time is relatively long, and the valve I is interlocked with the temperature sensor II and the flow meter (which can be connected to the DCS system) to facilitate real-time adjustment of the supply of the heat exchange medium, stabilize the temperature in the hydrolysis reactor, and ensure complete hydrolysis within the set time range.

[0020] Fourth, in the utility model, a stirring mechanism is provided on the hydrolysis reactor to stir the materials and increase the hydrolysis rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the utility model.

[0022] Figure 2 It is a structural schematic diagram of another implementation method.

[0023] Figure 3 It is a structural schematic diagram of a preferred embodiment of a hydrolysis reactor.

[0024] Figure 4 It is a structural schematic diagram of another embodiment of the residual liquid treatment system.

[0025] Among them, 1. hydrolysis reactor; 2. vacuum distillation device I; 3. vacuum distillation device II; 4. distillation tower; 5. ethanol extraction pipe; 6. methyl phosphite monoethyl extraction pipeline; 7. diethyl phosphite pipeline; 8. nitrogen replacement pipeline; 9. deionized water supply pipeline; 10. jacket; 11. temperature sensor I; 12. pressure sensor I; 13. pressure sensor II; 14. temperature sensor II; 15. flow meter; 16. valve I; 17. temperature sensor III; 18. temperature sensor IV; 19. Waste liquid storage tank; 20. Intermediate tank I; 21. Intermediate tank II; 22. Ethanol receiving tank; 23. Diethyl phosphite receiving tank; 24. Monoethyl methyl phosphite receiving tank; 25. Heat exchanger; 26. Vacuum subsystem; 27. Water storage tank; 1.1. Inlet; 1.2. Liquid outlet; 1.3. Stirring mechanism; 2.1. Feed inlet I; 2.2. Discharge port I; 3.1. Feed inlet II; 4.1. Residual liquid outlet; 10.1. Heat exchange medium inlet pipe; 10.2. Heat exchange medium discharge pipe. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with the embodiments, but the implementation manner of the present invention is not limited thereto.

[0027] Example 1

[0028] This embodiment is the most basic implementation method, a residual liquid treatment system in the synthesis process of diethyl methyl phosphite, belongs to the technical field of residual liquid treatment in the production of diethyl methyl phosphite, and includes a hydrolysis reactor 1, a vacuum distillation device Ⅰ2 and a vacuum distillation device Ⅱ3, wherein the inlet 1.1 of the hydrolysis reactor 1 is connected to the residual liquid outlet 4.1 of the distillation tower 4, the liquid outlet 1.2 of the hydrolysis reactor 1 is connected to the feed port Ⅰ2.1 of the vacuum distillation device Ⅰ2, an ethanol extraction pipe 5 is arranged above the vacuum distillation device Ⅰ2, the discharge port Ⅰ2.2 of the vacuum distillation device Ⅰ2 is connected to the feed port Ⅱ3.1 of the vacuum distillation device Ⅱ3, and the vacuum distillation device Ⅱ3 is provided with a monoethyl methyl phosphite extraction pipeline 6 and a diethyl phosphite pipeline 7,

[0029] The hydrolysis reactor 1 is connected to a nitrogen replacement pipeline 8 and a deionized water supply pipeline 9. A jacket 10 through which a heat exchange medium passes is arranged outside the hydrolysis reactor 1. A temperature sensor Ⅰ11 is arranged on the hydrolysis reactor 1. A pressure sensor Ⅰ12 is arranged on the vacuum distillation device Ⅰ2. A pressure sensor Ⅱ13 is arranged on the vacuum distillation device Ⅱ3.

[0030] At present, the synthesis technology of diethyl methyl phosphite is mainly to obtain it by esterification and distillation of methyl phosphorus dichloride. The residual liquid after distillation is transported from the residual liquid outlet 4.1 of the distillation tower 4 to the inlet 1.1 of the hydrolysis reaction. The material is first gas-displaced by nitrogen introduced through the nitrogen replacement pipeline 8 in the hydrolysis reactor 1, and then an appropriate amount of deionized water is added through the deionized water supply pipeline 9 to carry out the hydrolysis reaction, and a heat exchange medium (such as hot water) is introduced through the jacket 10 to allow the material to react at an appropriate temperature (to achieve the insulation effect) to increase the reaction rate. The reacted material is sent to the vacuum distillation device I2 through the liquid outlet 1.2, and ethanol is first separated under appropriate pressure conditions, and the ethanol in the reaction liquid is recovered through the ethanol extraction pipe 5; the remaining material is then sent to the vacuum distillation device II3, and under appropriate pressure conditions, the vacuum distillation is separated by methyl phosphite monoethyl ester and diethyl phosphite, and the methyl phosphite monoethyl ester is recovered through the methyl phosphite extraction pipeline 6, and the diethyl phosphite is recovered through the diethyl phosphite pipeline 7.

[0031] The pressure sensor I12 is used to monitor the pressure in the vacuum distillation device I2; the pressure sensor II13 is used to monitor the pressure in the vacuum distillation device II3. The temperature sensor I11 is used to detect the temperature in the hydrolysis reactor 1 and assist in monitoring the temperature in the hydrolysis reactor 1.

[0032] In this embodiment, the vacuum distillation device I2 is preferably a thin film evaporator; the vacuum distillation device II3 is a distillation tower.

[0033] Example 2

[0034] Compared with Example 1, the present embodiment is different in that the jacket 10 is connected with a heat exchange medium inlet pipe 10.1 and a heat exchange medium discharge pipe 10.2, and the heat exchange medium inlet pipe 10.1 is provided with a temperature sensor II 14, a flow meter 15, and a valve I 16. The heat exchange medium can be hot water, and the medium after heat exchange generally has a certain temperature. The low-temperature water after heat exchange can be further heated and used as a heat source to supply heat to the hydrolysis reactor 1. Such a structure facilitates the recovery and utilization of heat and reduces the cost of residual liquid treatment.

[0035] Preferably, the valve I 16 is respectively connected to the temperature sensor II 14 and the flow meter 15 for controlling, so as to realize automatic control.

[0036] Example 3

[0037] Compared with Embodiment 1-2, this embodiment is different in that the vacuum distillation device I2 is provided with a temperature sensor III 17; and the vacuum distillation device II3 is provided with a temperature sensor IV 18. The temperature sensor III 17 and the temperature sensor IV 18 can assist in monitoring whether the equipment is operating normally.

[0038] Example 4

[0039] The present embodiment is different from Embodiments 1-3 in that a stirring mechanism 1.3 is provided on the hydrolysis reactor 1 to increase the reaction rate of the material in the hydrolysis reactor 1.

[0040] Example 5

[0041] The difference between this embodiment and embodiments 1-4 is that, Figure 4 An intermediate tank I20 is provided between the distillation tower 4 and the hydrolysis reactor 1; an intermediate tank II21 is provided between the vacuum distillation device I2 and the vacuum distillation device II3.

[0042] Example 6

[0043] This embodiment takes the residual liquid treatment system in the synthesis process of diethyl monomethyl phosphite as an example to further illustrate this solution.

[0044] refer to Figure 2 The treatment system specifically comprises a hydrolysis reactor 1, a vacuum distillation device Ⅰ2 and a vacuum distillation device Ⅱ3, wherein the inlet 1.1 of the hydrolysis reactor 1 is connected to the residual liquid outlet 4.1 of the distillation tower 4, the liquid outlet 1.2 of the hydrolysis reactor 1 is connected to the feed inlet Ⅰ2.1 of the vacuum distillation device Ⅰ2, an ethanol extraction pipe 5 is arranged above the vacuum distillation device Ⅰ2, the discharge port Ⅰ2.2 of the vacuum distillation device Ⅰ2 is connected to the feed inlet Ⅱ3.1 of the vacuum distillation device Ⅱ3, and a methyl phosphite monoethyl ester extraction pipeline 6 and a diethyl phosphite pipeline 7 are arranged on the vacuum distillation device Ⅱ3,

[0045] The hydrolysis reactor 1 is connected to a nitrogen replacement pipeline 8 and a deionized water supply pipeline 9. A jacket 10 through which a heat exchange medium passes is arranged outside the hydrolysis reactor 1. A temperature sensor Ⅰ11 is arranged on the hydrolysis reactor 1. A pressure sensor Ⅰ12 is arranged on the vacuum distillation device Ⅰ2. A pressure sensor Ⅱ13 is arranged on the vacuum distillation device Ⅱ3.

[0046] In this embodiment, the jacket 10 is connected with a heat exchange medium inlet pipe 10.1 and a heat exchange medium discharge pipe 10.2. The heat exchange medium inlet pipe 10.1 is provided with a temperature sensor II 14, a flow meter 15, and a valve I 16. The valve I 16 is respectively controlled and connected with the temperature sensor II 14 and the flow meter 15.

[0047] In this embodiment, the vacuum distillation apparatus I2 is provided with a temperature sensor III17; the vacuum distillation apparatus II3 is provided with a temperature sensor IV18.

[0048] In this embodiment, the hydrolysis reactor 1 is provided with a stirring mechanism 1.3, Figure 3 .

[0049] In this embodiment, the vacuum distillation device I2 is preferably a thin film evaporator; the vacuum distillation device II3 is a distillation tower.

[0050] At present, the synthesis of diethyl methyl phosphite is obtained by esterification and distillation of methyl phosphorus dichloride. Since methyl phosphorus dichloride generally contains 2% to 5% of phosphorus trichloride and some side reactions occur during the esterification reaction, the residual liquid remaining after distillation in the distillation tower mainly contains triethyl phosphite, diethyl phosphite, monoethyl methyl phosphite, and a small amount of diethyl methyl phosphite.

[0051] Based on this processing system, the specific operation method is as follows:

[0052] Ⅰ. The residual liquid obtained after the treatment in the distillation tower is transported from the residual liquid outlet 4.1 to the hydrolysis reactor 1. The nitrogen replacement pipeline 8 is first opened to replace the hydrolysis reactor 1 with nitrogen;

[0053] Ⅱ. Open valve Ⅰ16, and introduce heat exchange medium into the jacket 10 of the hydrolysis reactor 1, and control the temperature in the hydrolysis reactor 1 to be within 60-85° C., and then add an appropriate amount of deionized water into the hydrolysis reactor 1 through the deionized water supply pipeline 9, and heat-insulate and hydrolyze;

[0054] III. After the heat preservation reaction is completed, the material is sent to the vacuum distillation device Ⅰ2 through the liquid outlet 1.2 of the hydrolysis reactor 1, and the pressure of the vacuum distillation device Ⅰ2 is controlled to be -95~-90kPa. The pressure in the vacuum distillation device Ⅰ2 is monitored by the pressure sensor Ⅰ12, and the vacuum distillation is performed, and the ethanol in the reaction liquid is recovered through the ethanol extraction pipe 5;

[0055] IV. After the ethanol is recovered, the remaining material is sent to the vacuum distillation device II3 through the discharge port I2.2 of the vacuum distillation device I2, and the pressure in the vacuum distillation device II3 is controlled to be -99.5~-99 kPa. The pressure in the vacuum distillation device II3 is monitored by the pressure sensor II13, and the methyl phosphite monoethyl ester and the diethyl phosphite are separated by vacuum distillation, and the methyl phosphite monoethyl ester is recovered through the methyl phosphite monoethyl ester extraction pipeline 6, and the diethyl phosphite is recovered through the diethyl phosphite pipeline 7. With the treatment system, the content of the obtained methyl phosphite monoethyl ester reaches 99% (A%, GC), and the content of the diethyl phosphite can reach 98.5% (A%, GC), so that the methyl phosphite monoethyl ester can be recycled as a raw material for glufosinate or some flame retardants, and the diethyl phosphite can be recycled as a raw material for various pesticides and plant growth regulators, so as to realize the recycling of phosphorus elements, reduce the pressure of waste liquid treatment, and reduce the damage to the environment.

[0056] In actual production, refer to Figure 4 Preferably, an intermediate tank I20 is provided between the distillation tower 4 and the hydrolysis reactor 1; an intermediate tank II21 is provided between the vacuum distillation device I2 and the vacuum distillation device II3. A booster pump can be designed on the pipeline for transferring materials. In order to ensure that the material is stable after the temperature is reduced or to facilitate direct reuse in the next process, a heat exchanger 25 can be added to the pipeline. The ethanol solvent separated by the vacuum distillation device I2 is sent to the ethanol receiving tank 22 through the ethanol extraction pipe 5 for temporary storage. The diethyl phosphite extracted through the diethyl phosphite pipeline 7 is temporarily stored in the diethyl phosphite receiving tank 23. Finally, the diethyl phosphite extracted from the bottom of the distillation tower 4 is temporarily stored in the diethyl phosphite receiving tank 23.

[0057] Preferably, the vacuum distillation device I2 and the vacuum distillation device II3 are connected to the vacuum subsystem 26. A waste liquid storage tank 19 is provided at the front end of the hydrolysis reactor 1 for temporarily storing the residual liquid removed from the bottom of the front distillation tower 4.

[0058] Preferably, the system is further provided with a water storage tank 27 for temporarily storing deionized water and supplying water to the hydrolysis reactor 1 through a deionized water pipeline.

Claims

1. A residual liquid treatment system in a diethyl methylphosphite synthesis process, characterized in that: The invention comprises a hydrolysis reactor (1), a vacuum distillation device I (2) and a vacuum distillation device II (3), wherein the inlet (1.1) of the hydrolysis reactor (1) is connected to the residual liquid outlet (4.1) of the rectification tower (4), the liquid outlet (1.2) of the hydrolysis reactor (1) is connected to the feed inlet I (2.1) of the vacuum distillation device I (2), an ethanol extraction pipe (5) is arranged above the vacuum distillation device I (2), the discharge inlet I (2.2) of the vacuum distillation device I (2) is connected to the feed inlet II (3.1) of the vacuum distillation device II (3), and the vacuum distillation device II (3) is provided with a methyl phosphite monoethyl ester extraction pipeline (6) and a diethyl phosphite pipeline (7), The hydrolysis reactor (1) is connected to a nitrogen replacement pipeline (8) and a deionized water supply pipeline (9); a jacket (10) through which a heat exchange medium passes is provided outside the hydrolysis reactor (1); a temperature sensor I (11) is provided on the hydrolysis reactor (1); a pressure sensor I (12) is provided on the vacuum distillation device I (2); and a pressure sensor II (13) is provided on the vacuum distillation device II (3).

2. A residual liquid treatment system in a diethyl methylphosphite synthesis process according to claim 1, characterized in that: The jacket (10) is connected to a heat exchange medium inlet pipe (10.1) and a heat exchange medium discharge pipe (10.2); the heat exchange medium inlet pipe (10.1) is provided with a temperature sensor II (14), a flow meter (15), and a valve I (16).

3. A residual liquid treatment system in a diethyl methylphosphite synthesis process according to claim 2, characterized in that: The valve I (16) is respectively control-connected to the temperature sensor II (14) and the flow meter (15).

4. The residual liquid treatment system in the diethyl methylphosphite synthesis process according to claim 1, characterized in that: The vacuum distillation device I (2) is provided with a temperature sensor III (17).

5. The residual liquid treatment system in the diethyl methyl phosphite synthesis process according to claim 1, characterized in that: The vacuum distillation device II (3) is provided with a temperature sensor IV (18).

6. The residual liquid treatment system in the diethyl methyl phosphite synthesis process according to claim 1, characterized in that: The hydrolysis reactor (1) is provided with a stirring mechanism (1.3).

7. The residual liquid treatment system in the diethyl methyl phosphite synthesis process according to claim 1, characterized in that: The vacuum distillation device I (2) is a thin film evaporator.

8. The residual liquid treatment system in the diethyl methylphosphite synthesis process according to claim 1, characterized in that: The vacuum distillation device II (3) is a distillation tower I.

9. The residual liquid treatment system in the diethyl methylphosphite synthesis process according to claim 1, characterized in that: An intermediate tank I (20) is provided between the distillation tower and the hydrolysis reactor; an intermediate tank II (21) is provided between the vacuum distillation device I (2) and the vacuum distillation device II (3).

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