P-chlorophenylglycine methanol solvent recovery system and method

Abstract

The invention relates to the technical field of solvent recovery, and particularly discloses a p-chlorophenylglycine methanol solvent recovery system and method.The system comprises a jet mixing unit, an outer cooling unit and an absorption condensation circulating unit which are connected with one another, and the technological process is as follows: after the cyanidation reaction of p-chlorophenylglycine is completed, reaction gas in a cyanidation kettle enters the absorption jet unit; the circulating pump pumps the absorption liquid in the circulating tank into the outer cooling unit for cooling, the cooled absorption liquid enters the jet mixing unit to mix and absorb tail gas containing methanol and ammonium bicarbonate, and the jet mixing unit adopts a variable-diameter guide plate and annularly arranged nozzles, so that the recovery time of methanol and ammonium bicarbonate is shortened to 3-4 hours; the recovery rate of methanol reaches 98%, the unit consumption of ammonium bicarbonate is reduced to 0.67 kg ammonium bicarbonate / 1kg p-chlorophenylglycine, the unit consumption of methanol and ammonium bicarbonate is reduced, the upper and lower box bodies of the outer cooler are arranged, the outer cooler does not need to be cleaned, and the environment and safety are managed and controlled.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solvent recovery, and specifically discloses a p-chlorobenzoglycine methanol solvent recovery system and method. BACKGROUND

[0002] P-chlorobenzoglycine is an important pesticide and pharmaceutical intermediate. A production route mainly uses sodium cyanide, p-chlorobenzaldehyde and ammonium bicarbonate as raw materials to obtain p-chlorobenzohydantoin by cyclization in a methanol solvent system, and then the p-chlorobenzohydantoin is subjected to alkaline hydrolysis and acidification to obtain the product p-chlorobenzoglycine.

[0003] The process route uses methanol as a solvent system to disperse p-chlorobenzaldehyde, so that the reaction is homogeneous. However, after the cyanation reaction is completed, the solvent needs to be heated and condensed for recovery. Due to the low mixing and absorption efficiency of water and cyanomethyl alcohol gas during the solvent condensation recovery process, the solvent recovery process has the problems of long recovery time (usually 7-8 hours), low production efficiency, difficult release of production capacity, low equipment utilization rate, insufficient condensation and absorption of methanol solvent, and inability to reuse ammonium bicarbonate after crystallization, resulting in high consumption of methanol solvent and ammonium bicarbonate, a methanol recovery rate of only 90% (methanol solvent consumption: 0.27 kg of methanol per kg of p-chlorobenzoglycine), ammonium bicarbonate consumption: 0.71 kg of ammonium bicarbonate per kg of p-chlorobenzoglycine, and high environmental protection treatment cost due to the exhaust gas entering the waste gas absorption system.

[0004] In the old process, the reaction gas in the cyanation kettle is condensed and recovered in the condenser, and carbon dioxide and ammonia gas are crystallized into ammonium bicarbonate in the condenser, which causes the condenser pipe to form a wall and even be blocked, resulting in poor methanol condensation effect, and some methanol cannot be condensed down. At the same time, the ammonium bicarbonate crystallized in the condenser needs to be heated and decomposed by steam before the next batch of operation and then discharged to the waste gas acid absorption system, resulting in low recovery of ammonium bicarbonate. SUMMARY

[0005] To solve the problem of methanol solvent recovery in the production of p-chlorobenzoglycine, the present application provides a p-chlorobenzoglycine methanol solvent recovery system to improve the methanol recovery rate and the ammonium bicarbonate recovery rate.

[0006] The present application provides a p-chlorobenzoglycine methanol solvent recovery system, which comprises, a jet mixing unit, which receives the absorption liquid from the cooling unit and mixes the absorption liquid with cyanomethyl alcohol gas to make the absorption liquid fully absorb the cyanomethyl alcohol gas; The jet flow mixing unit comprises a jet flow mixer, the jet flow mixer comprises a first pipe section, a variable-diameter guide plate is arranged in the first pipe section, mixing spaces are formed between adjacent variable-diameter guide plates, and the absorption liquid and the cyanomethyl alcohol gas are contacted in the mixing spaces and then are transported to a second pipe section, pass through the second pipe section, and are output to an absorption condensation circulation unit.

[0007] In some embodiments, the variable-diameter guide plate has a conical shell structure of a flow channel, one end of the variable-diameter guide plate is a first port, and the other end is a second port, The absorption liquid enters from the first port and flows out from the second port, and the absorption liquid absorbs the cyanomethyl alcohol gas in the mixing spaces.

[0008] In some embodiments, the first pipe section is further provided with a nozzle pipe plate, the nozzle pipe plate is provided with a plurality of nozzles, the nozzles comprise nozzle channels, the absorption liquid enters the first pipe section, is transported to the variable-diameter guide plate through the nozzle channels, and the plurality of nozzles are annularly arranged on the nozzle pipe plate. In some embodiments, the nozzle pipe plate is disc-shaped, and the nozzle channels gradually approach the center line of the nozzle pipe plate along the flow direction of the absorption liquid.

[0009] In some embodiments, the second pipe is provided with a throat pipe, the throat pipe comprises a narrowing part, a first throat pipe section and a second throat pipe section connected to two ends of the narrowing part, and the first throat pipe section and the second throat pipe section are arranged in different diameters.

[0010] In some embodiments, the first throat pipe section and the second throat pipe section comprise a large-end and a small-end, the narrowing part is connected to the small-end, and the first throat pipe section, the second throat pipe section and the narrowing part are connected to form a liquid flow channel.

[0011] In some embodiments, the p-chlorophenylglycine methanol solvent recovery system further comprises an absorption condensation circulation unit, the absorption condensation circulation unit comprises a circulation tank, the circulation tank is in fluid communication with the second pipe section to receive the absorption liquid from the jet flow mixing unit.

[0012] In some embodiments, the p-chlorophenylglycine methanol solvent recovery system further comprises an external cooling unit, the external cooling unit comprises an external cooler, the absorption liquid in the circulation tank is pumped to a coil pipe by a circulation pump, the inner wall of the external cooler is connected with a plurality of guide cooling plates, cooling water flows in the external cooler and presents an S-shaped flow path under the action of the guide cooling plates.

[0013] In some embodiments, the absorption liquid is cooled by the external cooling unit and then enters the jet flow mixer to absorb the cyanomethyl alcohol gas.

[0014] The second aspect of the present application provides a p-chlorophenylglycine methanol solvent recovery method, comprising: Step 1: add the absorption liquid into the circulating tank, the absorption liquid includes water; Step 2: pump the absorption liquid in the circulating tank to the outer cooler, the absorption liquid is cooled by the outer cooler and then enters the mixing space of the jet mixing unit, mixed and absorbed with the cyanated methanol gas, and then returns to the circulating tank to continue Step 2 until the absorption liquid is saturated.

[0015] The process is as follows: after the cyanation reaction of p-chlorophenyl glycine is completed, the cyanation reactor gas including water vapor, methanol, carbon dioxide and ammonia is recovered, the cyanation reactor gas enters the jet mixing unit, the circulating pump pumps the absorption liquid in the circulating tank into the outer cooling unit for cooling, and then the cooled absorption liquid enters the jet mixing unit to mix and absorb the cyanation reactor gas, so that methanol is condensed and recovered and ammonium bicarbonate is dissolved and recovered. The absorption solves the problems of: 1. The recovery time is shortened to 3-4 hours, 2. The methanol recovery rate reaches 98%, the ammonium bicarbonate consumption is reduced to 0.67 kg ammonium bicarbonate / kg p-chlorophenyl glycine, and the consumption of methanol and ammonium bicarbonate is reduced. 3. No need to clean the outer cooler, the environment and safety are controlled. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 Structure diagram of jet mixer; Figure 2 Figure 1 B-B direction sectional view of jet mixer; Figure 3 Jet unit shell, second pipe section sectional view and internal structure diagram of jet mixer; Figure 4 Structure diagram of nozzle pipe plate; Figure 5 Figure 4 A-A direction sectional view; Figure 6 Internal flow path diagram of outer cooler; Figure 7 Connection diagram of p-chlorophenyl glycine methanol solvent recovery system.

[0017] FIGURE DESCRIPTION: 1, jet mixing unit; 10, jet mixer; 101, first pipe section; 1011, circulating absorbent liquid inlet; 1021, first throat pipe section; 1022, narrowing part; 1023, second throat pipe section; 103, second pipe section; 104, variable-diameter guide plate; 1041, first port; 1042, second port; 105, jet mixing unit housing; 106, nozzle; 1061, nozzle channel; 107, nozzle pipe plate; 1071, nozzle pipe plate center line; 1081, air inlet adjusting valve; 12, jet mixing unit liquid inlet pipe; 13, jet mixing unit liquid outlet pipe; 1012, jet mixer air inlet; 2, external cooling unit; 21, external cooler; 211, upper box; 2111, upper box first space; 2112, upper box second space; 2113, upper box third space; 212, lower box; 2121, lower box first space; 2122, lower box second space; 213, coil pipe; 214, guide cooling plate; 216, external circulating cooling water inlet; 217, external circulating cooling water outlet; 218, exhaust valve; 219, external circulating exhaust; 22, circulating pump; 23, circulating pump liquid inlet pipe; 24, circulating pump liquid outlet pipe; 3, absorption condensation cycle unit; 30, circulating tank; 301, jacket; 31, circulating tank cooling water inlet adjusting valve. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application, that is, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments.

[0019] The first aspect of the present application provides a p-chlorophenylglycine methanol solvent recovery system, comprising a jet mixing unit 1, the jet mixing unit 1 receives an absorbent liquid from an external cooling unit 2, and mixes the absorbent liquid with cyanide methanol gas to make the absorbent liquid fully absorb the cyanide methanol gas; The jet mixing unit 1 comprises a jet mixer 10, the jet mixer 10 comprises a first pipe section 101, a plurality of variable-diameter guide plates 104 are arranged in the first pipe section 101, edges of the plurality of variable-diameter guide plates 104 are fixedly connected to a jet mixing unit housing 105, the variable-diameter guide plate 104 is a conical shell structure with a flow channel, one end of the conical shell structure is a first port 1041, and the other end is a second port 1042, an opening size of the first port 1041 is greater than an opening size of the second port 1042; The plurality of variable diameter guide plates 104 form mixing spaces between them. After the absorption liquid and the cyanomethanol gas contact in the mixing spaces, the absorption liquid is transported to the second pipe section 103. Through the second pipe section 103, the fully absorbed absorption liquid is output to the absorption condensation circulation unit 3.

[0020] Preferably, the length of the second pipe section 103 is greater than 4m, so as to facilitate the mixing and cooling of the absorption liquid in the second pipe section 103.

[0021] The absorption liquid enters from the first port 1041 and flows out from the second port 1042. The first port 1041 and the second port 1042 of the adjacent variable diameter guide plates 104 form a mixing space. The absorption liquid absorbs the cyanomethanol gas in the mixing space.

[0022] The variable diameter guide plates 104 are arranged to facilitate the uniform distribution of the cyanomethanol gas entering the jet mixer 10, and facilitate the full absorption of the absorption liquid to the cyanomethanol.

[0023] In some optional embodiments, the second pipe is provided with a throat pipe, which includes a narrowing portion 1022, and a first throat pipe section 1021 and a second throat pipe section 1023 connected to both ends of the narrowing portion 1022. The first throat pipe section 1021 and the second throat pipe section 1023 are arranged in a variable diameter shape like a horn. The narrowing portion is a hollow cylindrical shape with open ends.

[0024] In some optional embodiments, the first throat pipe section 1021 and the second throat pipe section 1023 include a large end and a small end. The narrowing portion 1022 is connected to the small end. The first throat pipe section 1021, the second throat pipe section 1023, and the narrowing portion 1022 are connected to form a liquid flow channel. The throat pipe is arranged to facilitate further absorption of the absorption liquid to the gas, and shorten the recovery time.

[0025] In some optional embodiments, the first pipe section 101 is further provided with a nozzle pipe plate 107. The nozzle pipe plate 107 is provided with a plurality of nozzles 106. The nozzles 106 include nozzle channels 1061. After the absorption liquid enters the first pipe section 101, it is transported to the first port 1041 through the nozzle channels 1061. The plurality of nozzles 106 are arranged in a ring shape and fixedly connected to the nozzle pipe plate 107.

[0026] Further preferably, the nozzle pipe plate 107 is in the shape of a circular disc, and the edge is fixed to the jet mixing unit housing 105. The nozzle channels 1061 gradually approach the nozzle pipe plate center line 1071 along the flow direction F2 of the absorption liquid.

[0027] Preferably, to ensure that the absorption liquid does not backmix in the first pipe section 101, the nozzle pipe plate center line 1071 axially passes through the internal space of the narrowing portion 1022.

[0028] Further preferably, in order to prevent the solid-containing absorption liquid from wearing the nozzle 106, the nozzle 106 is made of 304 material.

[0029] The absorption liquid containing cyanide methanol gas is output to the absorption condensation circulating unit 3 through the second pipe section 103 and the jet mixing unit outlet pipe 13, the jet mixing unit outlet pipe 13 extends into the circulating tank 30, the outlet of the jet mixing unit outlet pipe 13 is 0.5 m away from the bottom of the circulating tank 30, the absorption liquid is pumped into the circulating tank 30 through the second pipe section 103 and the jet mixing unit outlet pipe 13, and the jet mixing unit outlet pipe 13 is inserted below the liquid level in the circulating tank 30 to effectively prevent the absorption condensation material from being released again.

[0030] Preferably, the circulating pump 22 has a lift greater than 60 m.

[0031] Preferably, the circulating tank 30 is wrapped with a jacket 301, and cooling water flows in the jacket 301, the jacket 301 absorbs and cools the circulating tank 30, and the cooling water in the jacket 301 is controlled by the circulating tank cooling water inlet adjusting valve 31.

[0032] The temperature of the material in the circulating tank 30 is controlled to be ≤45℃ by the opening degree of the circulating tank cooling water inlet adjusting valve 31, so that the ammonium bicarbonate solid in the absorption liquid is precipitated.

[0033] The p-chlorophenylglycine methanol solvent recovery system further comprises an external cooling unit 2, the external cooling unit 2 comprises a circulating pump 22 and an external cooler 21, the circulating pump 22 is used to pump the absorption liquid in the circulating tank 30 to the external cooler 21, the circulating pump inlet pipe 23 is connected to the liquid inlet of the circulating pump 22, one end of the circulating pump inlet pipe 23 is connected to the liquid inlet of the circulating pump 22, and the other end extends into the circulating tank 30, the circulating pump outlet pipe 24 is connected to the liquid outlet of the circulating pump 22, one end of the circulating pump outlet pipe 24 is connected to the liquid outlet of the circulating pump 22, and the other end is connected to the first space 2111 of the upper box body.

[0034] As shown in Figure 6 The upper box body 211 is divided into an upper box body first space 2111, an upper box body second space 2112, and an upper box body third space 2113 by a partition, the lower box body 212 is divided into a lower box body first space 2121 and a lower box body second space 2122 by a partition, the lower box body first space 2121 is in liquid communication with the upper box body first space 2111 and the upper box body second space 2112 through part of the coil pipe 213, and the lower box body second space 2122 is in liquid communication with the upper box body second space 2112 and the upper box body third space 2113 through part of the coil pipe 213.

[0035] The absorbent liquid in the circulating tank 30 is pumped to the external cooler 21 by the circulating pump 22. The flow path of the absorbent liquid in the external cooler 21 is as follows: Figure 6 As shown by arrow F2, the coil passes through the first space 2111 of the upper housing, part of the coil 213, the first space 2121 of the lower housing, part of the coil 213, the second space 2112 of the upper housing, part of the coil 213, the second space 2122 of the lower housing, part of the coil 213, the second space 2113 of the upper housing, and then flows from the second space 2113 of the upper housing to the circulating absorbent inlet 1011. This F2 path can significantly increase the contact area between the coil 213 and the cooling water.

[0036] The lower housing 212 is connected to an external circulation drain 219, which is equipped with a drain valve 218. The drain valve 218 controls the absorption liquid in the lower housing 212 to flow out to the circulation tank 30. When the absorption liquid is saturated, the circulation pump 22 stops, the drain valve 218 opens, and the absorption liquid in the external cooler 21 is drained to the circulation tank 30 to prevent the coil 213 in the external cooler 21 from becoming blocked.

[0037] In some optional embodiments, a plurality of flow-guiding cooling plates 214 are fixedly connected to the inner wall of the external cooler 21. Cooling water flows inside the external cooler 21, forming an S-shaped flow path under the action of the flow-guiding cooling plates 214, such as... Figure 6 As indicated by arrow F1, the cooling water flows in from the external circulation cooling water inlet 216 and flows out from the external circulation cooling water outlet 217.

[0038] After being cooled by the external cooler 21, the absorbent is output from the third space 2113 of the upper box to the inlet pipe 12 of the jet mixing unit, and then enters the circulating absorbent inlet 1011 of the jet mixer 10 through the inlet pipe 12 of the jet mixing unit, where it absorbs the methanol cyanide gas in the mixing space of the jet mixer 10.

[0039] A second aspect of this invention provides a method for recovering p-chlorophenylglycine from methanol solvent, comprising: Step 1: Control the temperature of the material in the circulating tank 30 to ≤45℃ by adjusting the opening of the cooling water inlet regulating valve 31 to facilitate the precipitation of ammonium bicarbonate solids; add absorbent liquid to the circulating tank 30. The absorbent liquid consists of 60% volume of the previous batch absorbent liquid + 40% volume of tap water. The volume of the absorbent liquid is the sum of the internal volume of the coil 213, the upper tank 211, the lower tank 212, the internal volume of the jet mixing unit inlet pipe 12, the volume of the circulating pump outlet pipe 24, and the volume of the circulating pump inlet pipe 23. The drain valve 218 is closed.

[0040] Step 2: Pump the absorbent liquid in the circulating tank 30 to the external cooler 21, the flow rate of the absorbent liquid in the coil 213 of the external cooler 21 is greater than 0.8 m / s, after cooling in the external cooler 21, the absorbent liquid enters the mixing space of the jet mixer 1, the inlet regulating valve 1081 is opened, the cyanide methanol recovery gas G1 enters the jet mixer inlet 1012 and mixes with the absorbent liquid in the mixing space, after the cyanide methanol gas is fully absorbed, the absorbent liquid returns to the circulating tank 30 and continues to circulate to perform step 2, the absorbent liquid in the circulating tank 30 is pumped to the external cooler 21, until the sample detection of the absorbent liquid in the circulating tank 30 is saturated, in this process, the absorbent liquid in the circulating tank 30 precipitates ammonium bicarbonate solid.

[0041] When the absorbent liquid is saturated, the circulating pump 22 stops running, the exhaust valve 218 is opened, and the absorbent liquid in the external cooler 21 is discharged to the circulating tank 30 to prevent solid material precipitation and settlement, causing the coil 213 to be blocked.

[0042] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Those skilled in the art can make various changes and modifications to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A system for recovering p-chlorophenylglycine methanol solvent, characterized in that, include, A jet mixing unit (1) receives absorbent from a cooling unit and mixes the absorbent with methanol cyanide gas to ensure that the absorbent fully absorbs the methanol cyanide gas. The jet mixing unit (1) includes a jet mixer (10), which includes a first pipe section (101). A variable diameter guide plate (104) is provided in the first pipe section (101), and a mixing space is formed between adjacent variable diameter guide plates (104). After the absorbent and methanol cyanide gas come into contact in the mixing space, the absorbent is transported to the second pipe section (103) and output to the absorption and condensation circulation unit (2) through the second pipe section (103).

2. The p-chlorophenylglycine methanol solvent recovery system according to claim 1, characterized in that, The variable diameter guide plate (104) is a conical shell structure with a flow channel. One end of the variable diameter guide plate (104) is a first opening (1041), and the other end is a second opening (1042). The absorbent enters through the first port (1041) and flows out through the second port (1042). The absorbent absorbs methanol cyanide gas in the mixing space.

3. The p-chlorophenylglycine methanol solvent recovery system according to claim 1 or 2, characterized in that, The first pipe section (101) is also provided with a nozzle tube plate (107), the nozzle tube plate (107) is provided with a plurality of nozzles (106), the nozzles (106) include nozzle channels (1061), after the absorbent enters the first pipe section (101), it is transported to the variable diameter guide plate (104) through the nozzle (106) channel, and the plurality of nozzles (106) are arranged in a ring on the nozzle tube plate (107).

4. The p-chlorophenylglycine methanol solvent recovery system according to any one of claims 1 to 3, characterized in that, The nozzle tube sheet (107) is disc-shaped, and the nozzle channel (1061) gradually approaches the center line (1071) of the nozzle tube sheet along the direction of the absorbent flow.

5. The p-chlorophenylglycine methanol solvent recovery system according to any one of claims 1 to 4, characterized in that, The second pipe is provided with a throat, the throat includes a narrowing section (1022), and a first throat section (1021) and a second throat section (1023) connected to both ends of the narrowing section (1022), the first throat section (1021) and the second throat section (1023) are configured to have different diameters.

6. The p-chlorophenylglycine methanol solvent recovery system according to claim 5, characterized in that, The first throat segment (1021) and the second throat segment (1023) include a large opening and a small opening. The narrowing part (1022) is connected to the small opening. The first throat segment (1021), the second throat segment (1023), and the narrowing part (1022) are connected to form a fluid flow channel.

7. The p-chlorophenylglycine methanol solvent recovery system according to any one of claims 1 to 6, characterized in that, It also includes an absorption and condensation circulation unit (2), which includes a circulation tank (30) in fluid communication with the second pipe section (104) to receive the absorbent from the jet mixing unit (1).

8. The p-chlorophenylglycine methanol solvent recovery system according to any one of claims 1 to 6, characterized in that, It also includes an external cooling unit (2), which includes an external cooler (21). The absorbent in the circulation tank (30) is pumped to the coil (213) by the circulation pump (22). The inner wall of the external cooler (21) is connected with several guide cooling plates (214). Cooling water flows in the external cooler (21) and presents an S-shaped flow path under the action of the guide cooling plates (214).

9. The p-chlorophenylglycine methanol solvent recovery system according to any one of claims 1 to 8, characterized in that, After being cooled by the external cooling unit (2), the absorbent enters the jet mixer (10) to absorb methanol cyanide gas.

10. A method for recovering p-chlorophenylglycine from methanol solvent, characterized in that, include: Step 1: Add absorbent liquid, which includes water, into the circulation tank; Step 2: Pump the absorbent in the circulating tank to the external cooler (21). After being cooled by the external cooler (21), it enters the mixing space of the jet mixing unit (1), mixes and absorbs with the methanol cyanide gas, and then returns to the circulating tank (30). Continue to perform step 2 until the absorbent is saturated.

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