A method for treating the chlorination neutralization solution of sucralose-6-ester

Abstract

This invention significantly reduces the impurity content in the resulting concentrated solution by first recovering trichloroethane and then DMF, thereby improving the yield and purity of the crude sucralose-6-ester. Furthermore, this invention utilizes weakly alkaline ammonia to adjust the pH of the system to 6-9, preventing excessive alkalinity from causing the alkaline hydrolysis of sucralose-6-ester to produce sucralose, thus further improving the yield and purity of the crude sucralose-6-ester. Moreover, this invention eliminates the need for large amounts of acid, hydrogen peroxide, organic solvents (in the oxidation reaction stage), and heat energy (in multiple thermal extractions), resulting in low treatment costs for the chlorination neutralization solution. In addition, the treatment method provided by this invention can improve the conversion rate and daily production capacity of sucralose-6-ester in the chlorination neutralization solution, reduce the generation of wastewater and waste activated carbon, resulting in less waste, lower energy consumption, and lower production costs.

Description

Technical Field

[0001] This invention relates to the field of sucralose production technology, and in particular to a method for treating a chlorinated neutralization solution of sucralose-6-ester. Background Technology

[0002] Sucralose, commonly known as sucralose, is a new generation of sweetener made from sucrose. It appears as a white crystalline powder or granules and is 600 times sweeter than sucrose. It has a pure taste, does not participate in human metabolism, and is a "zero-calorie" sugar suitable for diabetics, patients with cardiovascular and cerebrovascular diseases, and the elderly. It also has the characteristics of good stability and high safety and is widely used in many fields such as food, beverages, daily chemicals, and medicine.

[0003] Currently, the production process of sucralose mainly involves the following five steps: (1) Acylation reaction: using sucrose as raw material, N,N-dimethylformamide (DMF) as solvent, organotin as catalyst, and acetic anhydride as acylation agent, the reaction product is sucrose-6-ethyl ester; (2) Chlorination reaction: using sucrose-6-ethyl ester as raw material, DMF and trichloroethane as solvent, the chlorination reaction is carried out under the action of chlorinating agent (Williams reagent or phosgene), the obtained chlorinated liquid is neutralized by liquid alkali or ammonia water, the obtained chlorinated neutralized liquid is evaporated to recover the solvent DMF and trichloroethane, then water is added to dissolve, and then the pure sucralose-6-acetate is obtained through multi-stage separation and purification steps; (3) Deacylation reaction: using high-purity sucralose-6-acetate as raw material, alkaline reagent (e.g. hydroxide, sodium alkoxide) as catalyst, and methanol as solvent, the deacylation reaction is carried out, and the product is separated and purified to obtain pure sucralose.

[0004] In the chlorination process of sucralose production, trichloroethane and DMF are used extensively as solvents. Currently, the main method for recovering solvent from the chlorination neutralization solution is to remove ammonium chloride by filtration, followed by direct distillation of the filtrate in a reactor using a jacketed heating method to recover the solvent. However, this process, under high-temperature distillation conditions, leads to DMF decomposition and loss, as well as the decomposition and coking of sucralose-6-ethyl ester. To completely recover the solvent, a large amount of pure water needs to be added during distillation to remove the solvent from the azeotropic zone. This process is complex, time-consuming, and results in low equipment utilization efficiency, while also generating a large amount of difficult-to-treat DMF-containing wastewater. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a method for treating the chlorination neutralization solution of sucralose-6-ester. The treatment method provided by the present invention does not require the addition of additional water to remove DMF, does not generate a large amount of DMF wastewater, has low energy consumption, and achieves high recovery rates and high purity of DMF and trichloroethane.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for treating a chlorinated neutralization solution of sucralose-6-ester, comprising the following steps:

[0008] (1) The chlorinated neutralized solution of sucralose-6-ester was pre-concentrated, condensed and separated in sequence to obtain the first DMF light phase and the first trichloroethane heavy phase, respectively; the pre-concentration temperature was 30-50℃;

[0009] (2) The first trichloroethane heavy phase is distilled to obtain a distilled gas phase and a distillation residue; the distilled gas phase is condensed and separated into two layers to obtain a second DMF light phase and a second trichloroethane heavy phase; the distillation temperature is 45-55℃.

[0010] (3) The second trichloroethane heavy phase is washed with water to obtain the first DMF-containing aqueous phase and the third trichloroethane heavy phase, respectively;

[0011] (4) The distillate residue is separated into layers, and the lower phase is washed with water to obtain a second aqueous phase containing DMF and a fourth heavy phase containing trichloroethane.

[0012] (5) The first DMF light phase, the second DMF light phase, the first DMF-containing aqueous phase and the second DMF-containing aqueous phase are distilled to obtain the DMF product;

[0013] (6) The third and fourth trichloroethane heavy phases are subjected to distillation to obtain trichloroethane product and distillation residue, respectively.

[0014] Steps (3) and (4) have no chronological order;

[0015] Steps (5) and (6) are not in any particular order.

[0016] Preferably, in step (1), the pressure of the pre-concentration is -90 to -95 kPa;

[0017] The pre-concentration includes sequentially performing a primary pre-concentration and a secondary pre-concentration, wherein the temperature of the primary pre-concentration is 45–50°C and the temperature of the secondary pre-concentration is 30–40°C.

[0018] The condensation includes a first condensation and a second condensation in sequence, wherein the temperature of the first condensation is 30-40°C and the temperature of the second condensation is 15-25°C;

[0019] Part of the first trichloroethane is recycled in a rephase cycle for the secondary pre-concentration.

[0020] Preferably, in step (2), the vacuum degree of the distillation is -85 to -92 kPa;

[0021] The ratio of the feed flow rate of the first trichloroethane heavy phase to the outflow rate of the distilled gas phase is 6.5-7:4-5;

[0022] The condensation includes a third condensation and a fourth condensation in sequence, wherein the temperature of the third condensation is 30-40°C and the temperature of the fourth condensation is 15-25°C.

[0023] The distillation is carried out in part by a second trichloroethane rephase cycle.

[0024] Preferably, in step (5), the distillation temperature is 95-111°C and the vacuum degree is -88±5kPa.

[0025] Preferably, in step (6), the distillation temperature is 60–83°C and the vacuum degree is -93±3 kPa.

[0026] Preferably, step (6) is followed by:

[0027] (7) The distillation is carried out using the residual liquid to obtain recovered tetramethylurea.

[0028] This invention provides a treatment device for the chlorination neutralization solution of sucralose-6-ester used in the above-described technical solution, which includes a pre-concentration unit, a distillation unit, a water washing unit, and a rectification unit connected in sequence according to the material flow order.

[0029] The pre-concentration unit includes: a pre-concentrator 1; a pre-concentration condenser 2 whose inlet is connected to the outlet of the pre-concentrator 1; and a first stratification tank 3 whose inlet is connected to the outlet of the pre-concentration condenser 2, wherein the trichloroethane outlet of the first stratification tank 3 is connected to the reflux inlet of the pre-concentration condenser 2.

[0030] The distillation unit includes: a distillation column 4, the inlet of which is connected to the trichloroethane outlet of the first layering tank 3, and the distillation column 4 is equipped with a second heater 4-1; a distillation condenser 5, the inlet of which is connected to the gas phase outlet of the distillation column 4; a second layering tank 6, the inlet of which is connected to the outlet of the distillation condenser 5, and the trichloroethane outlet of the second layering tank 6 is connected to the reflux inlet of the distillation column 4; and a layering vessel 7, the inlet of which is connected to the bottom outlet of the distillation column 4.

[0031] The washing unit includes: a first washing chamber 8 whose inlet is connected to the trichloroethane outlet of the second layering tank 6; and a second washing chamber 9 whose inlet is connected to the outlet of the layering vessel 7, wherein the second washing chamber 8 is provided with a water inlet;

[0032] The distillation unit includes a trichloroethane distillation unit and a DMF distillation unit;

[0033] The trichloroethane distillation unit includes: a trichloroethane distillation column 10 connected to the trichloroethane outlet of the first water washing chamber 8; and a trichloroethane distillation condenser 11 whose inlet is connected to the top outlet of the trichloroethane distillation column 10.

[0034] The DMF distillation unit includes a DMF distillation column 14 whose inlet is connected to the DMF outlet of the first stratification tank 3, the DMF outlet of the second stratification tank 6, the aqueous phase outlet of the first washing chamber 8, and the aqueous phase outlet of the second washing chamber 9, respectively.

[0035] Preferably, the pre-concentrator 1 includes several pre-concentration vessels 1-1, and a pre-concentration tower 1-2 whose inlet is connected to the outlet of each of the several pre-concentration vessels 1-1, and the pre-concentration tower 1-2 is provided with a first heater 1-2-1.

[0036] Preferably, the pre-concentration condenser 2 includes a first pre-concentration condenser 2-1, a second pre-concentration condenser 2-2 whose inlet is connected to the outlet of the first pre-concentration condenser 2-1, and a reflux inlet of the second pre-concentration condenser 2-2 connected to the trichloroethane outlet of the first trichloroethane phase tank 3.

[0037] Preferably, the distillation condenser 5 includes a first distillation condenser 5-1 and a second distillation condenser 5-2 whose inlet is connected to the outlet of the first distillation condenser 5-1.

[0038] Preferably, the trichloroethane distillation condenser 11 includes a first trichloroethane distillation condenser 11-1 and a second trichloroethane distillation condenser 11-2 whose inlet is connected to the outlet of the first trichloroethane distillation condenser 11-1.

[0039] Preferably, the trichloroethane distillation unit further includes a trichloroethane product tank 12 and a residual liquid transfer tank 13. The inlet of the trichloroethane product tank 12 is connected to the outlet of the trichloroethane distillation condenser 11, and the inlet of the residual liquid transfer tank 13 is connected to the residual liquid outlet of the trichloroethane distillation column 10.

[0040] Preferably, the distillation unit further includes a tetramethylurea distillation unit; the tetramethylurea distillation unit includes: a tetramethylurea distillation column 15; a tetramethylurea distillation condenser 16 whose inlet is connected to the top outlet of the tetramethylurea distillation column 15; and a tetramethylurea recovery tank 17 whose inlet is connected to the outlet of the tetramethylurea distillation condenser 16.

[0041] This invention provides a method for treating a chlorinated neutralized solution of sucralose-6-ester, comprising the following steps: (1) pre-concentrating, condensing, and separating the chlorinated neutralized solution of sucralose-6-ester sequentially to obtain a first DMF light phase and a first trichloroethane heavy phase; the pre-concentration temperature is 30-50°C; (2) distilling the first trichloroethane heavy phase to obtain a distilled gas phase and a distillation residue; condensing the distilled gas phase and separating it into a second DMF light phase and a second trichloroethane heavy phase; the distillation temperature is 45-55°C; (3) washing the second trichloroethane heavy phase with water. (3) A first DMF-containing aqueous phase and a third trichloroethane heavy phase are obtained respectively; (4) The distillation residue is separated into layers, and the lower phase is washed with water to obtain a second DMF-containing aqueous phase and a fourth trichloroethane heavy phase respectively; (5) The first DMF light phase, the second DMF light phase, the first DMF-containing aqueous phase and the second DMF-containing aqueous phase are distilled to obtain DMF product; (6) The third trichloroethane heavy phase and the fourth trichloroethane heavy phase are distilled to obtain trichloroethane product and distillation residue respectively; Steps (3) and (4) have no time sequence; Steps (5) and (6) have no time sequence. This invention significantly shortens the distillation time by pre-concentrating, condensing, and separating the distillate before distillation of the chlorinated neutralization solution. Distillation is carried out at low temperatures (45–55°C), greatly reducing side reactions (DMF decomposition, sucralose-6-ethyl ester decomposition, and coking), thus increasing the yields of DMF and sucralose-6-ethyl ester. Furthermore, pre-concentration eliminates the need for adding pure water as an azeotropic solvent during distillation, preventing the generation of large amounts of DMF-containing wastewater, making it environmentally friendly. This invention removes residual DMF from the trichloroethane phase by washing the second trichloroethane heavy phase with water, significantly improving the purity of trichloroethane and greatly shortening the subsequent trichloroethane rectification time, thereby improving the treatment effect of the chlorinated neutralization solution. This invention also improves the DMF yield by washing the distillation residue after separation with water. Finally, this invention significantly improves the DMF yield by rectifying the DMF phase generated in each step. The processing method provided by this invention reduces byproducts and caramelization of hexaethyl ester by rapidly concentrating the chlorination neutralization solution, improves the conversion rate of sucralose-6-ethyl ester intermediate, saves steam, and reduces the generation of waste residue and waste liquid. Solvent recovery is time-efficient, the chlorination neutralization solution treatment efficiency is high, and the recovery rates and purity of trichloroethane and DMF are high, with low solvent recovery costs. This method significantly reduces side reactions generated during the chlorination reaction, substantially increases the yield of sucralose-6-ethyl ester in the chlorination neutralization stage, and the purity of the sucralose product synthesized from the chlorination neutralization solution treated by this method is above 99.5%, greatly improving the yield and purity of sucralose.

[0042] Furthermore, by using the residual liquid from the distillation process of trichloroethane, the present invention can fully recover tetramethylurea from the chlorination neutralization solution, resulting in a high yield and high purity of tetramethylurea.

[0043] This invention provides a treatment apparatus for the chlorination neutralization solution of sucralose-6-ester used in the above-described technical solution. The apparatus provided by this invention can achieve efficient recovery of DMF and trichloroethane from the chlorination neutralization solution of sucralose-6-ester, resulting in high yields and high purity of DMF and trichloroethane, while significantly reducing the amount of waste liquid and residue. Furthermore, the apparatus provides significantly reduces the occurrence of side reactions in the chlorination neutralization solution, and significantly improves the yield of sucralose-6-ethyl ester in the chlorination neutralization stage, as well as the yield and purity of sucralose in the subsequent process.

[0044] Furthermore, the processing device provided by the present invention can also fully recover tetramethylurea from the chlorination neutralization solution, and the obtained tetramethylurea has a high yield and high purity. Attached Figure Description

[0045] Figure 1This is a schematic diagram of a treatment apparatus for the chlorination neutralization solution of sucralose-6-ester. In this apparatus, 1 is a pre-concentrator 1, 1-1 is a pre-concentration vessel, 1-1-1 is the first pre-concentration vessel, 1-1-2 is the second pre-concentration vessel, 1-2 is a pre-concentration tower, 1-2-1 is the first heater, 1-3 is a chlorination neutralization solution storage tank, 1-4 is a concentration vessel, 1-5 is the first separation tank, 1-6 is the first vacuum pump, 2 is a pre-concentration condenser, 2-1 is the first pre-concentration condenser, 2-2 is the second pre-concentration condenser, 3 is the first stratification tank, 3-1 is the first DMF phase tank, 3-2 is the first trichloroethane phase tank, 4 is a distillation tower, 4-1 is the second heater, 5 is a distillation condenser, 5-1 is the first distillation condenser, 5-2 is the second distillation condenser, 5-3 is the second separation tank, 5-4 is the second vacuum pump, 6 is the second stratification tank, 6-1 is the second DMF phase tank, 6-2 is the second trichloroethane phase tank. 6-3 is the finished product tank, 7 is the layered reactor, 8 is the first water washing chamber, 8-1 is the first DMF-containing aqueous phase tank, 8-2 is the third trichloroethane phase tank, 9 is the second water washing chamber, 9-1 is the second DMF-containing aqueous phase tank, 9-2 is the fourth trichloroethane phase tank, 10 is the trichloroethane distillation column, 11 is the trichloroethane distillation condenser, 11-1 is the first trichloroethane distillation condenser, 11-2 is the second trichloroethane distillation condenser. The equipment includes: 12 is the trichloroethane finished product tank; 13 is the residual liquid transfer tank; 14 is the DMF distillation column; 15 is the tetramethylurea distillation column; 16 is the tetramethylurea distillation condenser; 17 is the tetramethylurea recovery tank; 17-1 is the reflux tank; 17-2 is the residual liquid recovery tank; 18-1 is the buffer tank; 18-2 is the final residual liquid tank; 19-1 is the third vacuum pump; 19-2 is the fourth vacuum pump; 19-3 is the fifth vacuum pump; and 19-4 is the sixth vacuum pump. Detailed Implementation

[0046] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0047] This invention provides a method for treating a chlorinated neutralization solution of sucralose-6-ester, comprising the following steps:

[0048] (1) The chlorinated neutralized solution of sucralose-6-ester was pre-concentrated, condensed and separated in sequence to obtain the first DMF light phase and the first trichloroethane heavy phase, respectively; the pre-concentration temperature was 30-50℃;

[0049] (2) The first trichloroethane heavy phase is distilled to obtain a distilled gas phase and a distillation residue; the distilled gas phase is condensed and separated into two layers to obtain a second DMF light phase and a second trichloroethane heavy phase; the distillation temperature is 45-55℃.

[0050] (3) The second trichloroethane heavy phase is washed with water to obtain the first DMF-containing aqueous phase and the third trichloroethane heavy phase, respectively;

[0051] (4) The distillate residue is separated into layers, and the lower phase is washed with water to obtain a second aqueous phase containing DMF and a fourth heavy phase containing trichloroethane.

[0052] (5) The first DMF light phase, the second DMF light phase, the first DMF-containing aqueous phase and the second DMF-containing aqueous phase are distilled to obtain the DMF product;

[0053] (6) The third and fourth trichloroethane heavy phases are subjected to distillation to obtain trichloroethane product and distillation residue, respectively.

[0054] Steps (3) and (4) have no chronological order;

[0055] Steps (5) and (6) are not in any particular order.

[0056] In this invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art.

[0057] In this invention, the chlorinated neutralized solution of sucralose-6-ester is sequentially pre-concentrated, condensed, and separated to obtain a first DMF light phase and a first trichloroethane heavy phase, respectively; the pre-concentration temperature is 30-50°C.

[0058] The present invention does not specifically limit the preparation method of the chlorination neutralization solution of sucralose-6-ester. A chlorination neutralization solution prepared from sucralose using sucrose as the initial raw material, as well known to those skilled in the art, can be used. Specifically, a solution containing sucralose-6-acetic acid ester is prepared using sucrose as the raw material, N,N-dimethylformamide (DMF) as the solvent, acetic anhydride as the acylating agent, and an organometallic catalyst. Then, a chlorination reaction is carried out using DMF and trichloroethane as solvents under the action of a chlorinating agent, followed by neutralization, to obtain the chlorination neutralization solution of sucralose-6-ester. In the present invention, the organometallic catalyst preferably includes dibutyltin oxide; the chlorinating agent preferably includes thionyl chloride; the alkali used for neutralization preferably includes ammonia, and the concentration of the ammonia is preferably 20-22 wt%, more preferably 20-21 wt%. The present invention does not specifically limit the amount of alkali used, as long as the pH of the system is adjusted to 9-10 (more preferably 9.5). After neutralization, the present invention preferably further includes adding acid to adjust the pH value to 6.5-7.5; the acid preferably includes hydrochloric acid, and the concentration of the hydrochloric acid is preferably 30-32 wt%, more preferably 31-32 wt%; the adjusted pH value is more preferably 7. In the present invention, the feed flow rate of the chlorination neutralization solution of sucralose-6-ester is preferably 3.5-4.5 m³ / h. 3 / h, more preferably 4m 3 / h.

[0059] In this invention, the pre-concentration pressure is preferably -90 to -95 kPa, more preferably -91 to -94 kPa, and even more preferably -92 to -93 kPa.

[0060] In this invention, the pre-concentration preferably includes sequential primary pre-concentration and secondary pre-concentration. The temperature of the primary pre-concentration is preferably 45-50°C, more preferably 46-48°C; the temperature of the secondary pre-concentration is preferably 30-40°C, and the secondary pre-concentration is preferably carried out in a pre-concentration tower. The top temperature of the pre-concentration tower is preferably 30-33°C, and the top temperature is preferably controlled by heavy phase reflux at the top of the tower. In this invention, the ratio of the feed flow rate to the heavy phase reflux flow rate of the pre-concentration tower is preferably 7-8:1.5-2.5, more preferably 7.5:2; the heavy phase reflux flow rate is preferably 0.3-0.5 m³ / s. 3 / h, more preferably 0.4m 3 / h; the temperature in the pre-concentration tower is preferably 35-38℃, and the bottom temperature of the pre-concentration tower is preferably 38-40℃.

[0061] In this invention, the condensation preferably includes a first condensation and a second condensation in sequence; the temperature of the first condensation is preferably 30-40°C, more preferably 32-36°C; the temperature of the second condensation is preferably 15-25°C, more preferably 20-22°C.

[0062] The present invention does not have any special limitation on the layering, and any layering method known to those skilled in the art can be used, such as using layering slots for layering.

[0063] In this invention, a portion of the first trichloroethane heavy phase is recycled for the secondary pre-concentration, and the volume of the portion of the first trichloroethane heavy phase accounts for 45-60% of the total volume of the first trichloroethane heavy phase, more preferably 50-55%.

[0064] After obtaining the first trichloroethane heavy phase, the present invention distills the first trichloroethane heavy phase to obtain a distilled gas phase and a distillation residue; the distilled gas phase is condensed and separated into two layers to obtain a second DMF light phase and a second trichloroethane heavy phase; the distillation temperature is 45-55℃.

[0065] In this invention, the distillation temperature is preferably 48–52°C, more preferably 50°C, and the distillation vacuum degree is preferably -85–-92 kPa, more preferably -87–-90 kPa, and even more preferably -88–-90 kPa.

[0066] In this invention, the ratio of the feed flow rate of the first trichloroethane heavy phase to the output flow rate of the distilled gas phase is preferably 6.5–7:4–5, more preferably 6.7–6.8:4.2–4.8; the output flow rate of the distilled gas phase is preferably 4–5 m³ / s. 3 / h, more preferably 4.5m 3 / h.

[0067] In this invention, the condensation preferably includes a third condensation and a fourth condensation in sequence; the temperature of the third condensation is preferably 30-40°C, more preferably 30-35°C; the temperature of the fourth condensation is preferably 15-25°C, more preferably 15-20°C.

[0068] In this invention, a portion of the second trichloroethane heavy phase is recycled for distillation, and the reflux rate of this portion of the second trichloroethane heavy phase is preferably 0.8–1.5 m³ / s. 3 / h, more preferably 1 to 1.2m 3 / h.

[0069] After obtaining the second trichloroethane heavy phase, the present invention washes the second trichloroethane heavy phase with water to obtain a first DMF-containing aqueous phase and a third trichloroethane heavy phase. In the present invention, the volume ratio of the second trichloroethane heavy phase to the washing water is preferably 1:0.4 to 0.6, more preferably 1:0.5.

[0070] After obtaining the distillation product residue, the present invention performs stratification on the distillation product residue, and washes the obtained lower phase with water to obtain a second DMF-containing aqueous phase and a fourth trichloroethane heavy phase. The present invention does not have any particular limitation on the stratification process; any stratification method well known to those skilled in the art can be used, such as using a stratification vessel. In the present invention, the volume ratio of the distillation product residue to the washing water is preferably 1:0.4 to 0.6, more preferably 1:0.5.

[0071] After obtaining the first DMF light phase, the second DMF light phase, the first DMF-containing aqueous phase, and the second DMF-containing aqueous phase, the present invention performs distillation on the first DMF light phase, the second DMF light phase, the first DMF-containing aqueous phase, and the second DMF-containing aqueous phase to obtain the DMF product. In this invention, the distillation temperature is preferably 95–111°C, the distillation is preferably carried out in a distillation column, the top temperature of the distillation column is preferably 95±5°C, the middle temperature of the column is preferably 100±5°C, and the bottom temperature of the column is preferably 106±5°C; the distillation pressure is preferably -88±5 kPa, more preferably -88±53 kPa. In this invention, the purity of the DMF product is preferably ≥99.5%, more preferably ≥99.8%, and the DMF content in the water flowing out from the bottom of the column is preferably ≤0.1 wt%.

[0072] After obtaining the first, second, third, and fourth trichloroethane heavy phases, the present invention performs distillation on the third and fourth trichloroethane heavy phases to obtain trichloroethane product and distillation residue, respectively.

[0073] In this invention, the distillation temperature is preferably 60-83°C, the distillation is preferably carried out in a distillation column, the top temperature of the distillation column is preferably 50±5°C, the middle temperature of the column is preferably 65±5°C, the bottom temperature of the column is preferably 78±5°C, and the distillation pressure is preferably -93±3 kPa, more preferably -93±1 kPa.

[0074] After obtaining the distillation residue, the present invention preferably further includes: distilling the distillation residue to obtain recovered tetramethylurea.

[0075] In this invention, the distillation temperature is preferably 70–115°C, and the vacuum degree is preferably -88–95 kPa, more preferably -90–-93 kPa. In this invention, the distillation is preferably carried out in a distillation column, the top temperature of the distillation column is preferably 70–75°C, more preferably 72–74°C; the top pressure of the distillation column is preferably -90–-95 kPa, more preferably -92–-93 kPa; the bottom temperature of the distillation column is preferably 105–115°C, more preferably 100°C; the reflux ratio of the distillation column is preferably 1–4, more preferably 1.2–4; and the top reflux flow rate of the distillation column is preferably 1.5–2 m³ / s. 3 / h, more preferably 1.6 to 1.8m 3 / h.

[0076] The distillation process further includes condensing the resulting distillate vapor phase to recover tetramethylurea. In this invention, the condensation temperature is preferably 15–20°C, more preferably 15–16°C. In this invention, the condensate obtained from condensation is preferably partially recycled for the distillation process, and the volume of the recycled condensate is preferably 15–25% of the total condensate volume, more preferably 20%. In this invention, when the tetramethylurea content used in the distillation is above 90%, it is preferable to collect the condensate, and the collection flow rate is preferably 1–1.5 m³ / s. 3 / h (more preferably 1.2 to 1.3m) 3 / h), the recovered tetramethylurea is preferably fed into a residual liquid recovery tank, and the bottom product of the distillation column is preferably discharged at 0.5-0.8m 3 / h (more preferably 0.6 to 0.7m) 3 The flow rate of / h) is delivered to the final residual liquid tank for use as fuel.

[0077] This invention provides a treatment device for the chlorination neutralization solution of sucralose-6-ester used in the above-described technical solution. The device is characterized by comprising a pre-concentration unit, a distillation unit, a water washing unit, and a rectification unit connected sequentially according to the material flow sequence. A schematic diagram of the treatment device is shown below. Figure 1 As shown below, in conjunction with Figure 1 The processing device will be described in detail.

[0078] The processing apparatus provided by the present invention includes a pre-concentration unit, which includes: a pre-concentrator 1; a pre-concentrator condenser 2 whose inlet is connected to the outlet of the pre-concentrator 1; and a first stratification tank 3 whose inlet is connected to the outlet of the pre-concentrator condenser 2, wherein the trichloroethane outlet of the first stratification tank 3 is connected to the reflux inlet of the pre-concentrator condenser 2.

[0079] In this invention, the pre-concentrator 1 preferably includes a plurality of pre-concentration vessels 1-1 and a pre-concentration tower 1-2 whose inlet is connected to the outlet of each of the plurality of pre-concentration vessels 1-1. The pre-concentration tower 1-2 is provided with a first heater 1-2-1. The number of pre-concentration vessels 1-1 is preferably two, referred to as the first pre-concentration vessel 1-1-1 and the second pre-concentration vessel 1-1-2. The outlets of the first pre-concentration vessel 1-1-1 and the second pre-concentration vessel 1-1-2 are respectively connected to the inlet of the pre-concentration tower 1-2. The outlet of the first pre-concentration vessel 1-1-1 and the inlet of the second pre-concentration vessel 1-1-2 are preferably connected through an overflow pipe.

[0080] In this invention, the pre-concentration condenser 2 preferably includes a first pre-concentration condenser 2-1 and a second pre-concentration condenser 2-2. The upper outlet of the first pre-concentration condenser 2-1 is connected to the inlet of the second pre-concentration condenser 2-2, and the bottom outlets of the first pre-concentration condenser 2-1 and the second pre-concentration condenser 2-2 are both connected to the inlet of the first layered tank 3.

[0081] In this invention, the pre-concentration unit preferably further comprises a first DMF phase tank 3-1, a first trichloroethane phase tank 3-2, a chlorination neutralization liquid storage tank 1-3, a concentration dryer 1-4, a first separation tank 1-5, and a first vacuum pump 1-6; the inlet of the first DMF phase tank 3-1 is connected to the DMF outlet of the first layering tank 3; the inlet of the first trichloroethane phase tank 3-2 is connected to the trichloroethane outlet of the first layering tank 3, and the outlet of the first trichloroethane phase tank 3-2 is connected to the reflux inlet of the pre-concentration tower 1-2 and the inlet of the distillation tower 4, respectively; the outlet of the chlorination neutralization liquid storage tank 1-3 is connected to the inlet of the first pre-concentration tank 1-1-1; the inlet of the concentration dryer 1-4 is connected to the outlet of the first pre-concentration tank 1-1-1 and the inlet of the second pre-concentration tank 1-1-2, respectively; the inlet of the first separation tank 1-5 is connected to the outlet of the second pre-concentration tank 1-1-2; and the inlet of the first vacuum pump 1-6 is connected to the outlet of the first separation tank 1-5.

[0082] The processing apparatus provided by the present invention includes a distillation unit, which includes: a distillation column 4, the inlet of which is connected to the trichloroethane outlet of the first layering tank 3, and the distillation column 4 is provided with a second heater 4-1; a distillation condenser 5, the inlet of which is connected to the gas phase outlet of the distillation column 4; a second layering tank 6, the inlet of which is connected to the outlet of the distillation condenser 5, and the trichloroethane outlet of the second layering tank 6 is connected to the reflux inlet of the distillation column 4; and a layering vessel 7, the inlet of which is connected to the bottom outlet of the distillation column 4.

[0083] In this invention, the distillation condenser 5 preferably includes a first distillation condenser 5-1 and a second distillation condenser 5-2. The inlet of the first distillation condenser 5-1 is connected to the top outlet of the distillation column 4, the upper outlet of the first distillation condenser 5-1 is connected to the inlet of the second distillation condenser 5-2, and the bottom outlets of the first distillation condenser 5-1 and the second distillation condenser 5-2 are both connected to the inlet of the second stratification tank 6.

[0084] In this invention, the distillation unit preferably further includes a second separation tank 5-3, a second vacuum pump 5-4, a second DMF phase tank 6-1, a second trichloroethane phase tank 6-2, and a finished product tank 6-3; the inlet of the second separation tank 5-3 is connected to the top outlet of the second distillation condenser 5-2, and the inlet of the second vacuum pump 5-4 is connected to the outlet of the second separation tank 5-3; the inlet of the second DMF phase tank 6-1 is connected to the DMF outlet of the second layering tank 6; the inlet of the second trichloroethane phase tank 6-2 is connected to the trichloroethane outlet of the second layering tank 6, the top outlet of the second trichloroethane phase tank 6-2 is connected to the finished product tank 6-3, and the bottom outlet of the second trichloroethane phase tank 6-2 is connected to the reflux inlet of the distillation column 4.

[0085] The processing device provided by the present invention includes a water washing unit, which includes: a first water washing chamber 8 whose inlet is connected to the trichloroethane outlet of the second layering tank 6; and a second water washing chamber 9 whose inlet is connected to the outlet of the layering vessel 7. Both the first water washing chamber 8 and the second water washing chamber 9 are provided with water inlets. The first water washing chamber 8 is preferably a water washing mixer.

[0086] In this invention, the inlet of the first washing chamber 8 is preferably connected to the outlet of the finished product tank 6-3. In this invention, a mixer is preferably installed inside the second washing chamber 9.

[0087] In this invention, the washing unit preferably further comprises a first DMF-containing aqueous phase tank 8-1, a third trichloroethane phase tank 8-2, a second DMF-containing aqueous phase tank 9-1, and a fourth trichloroethane phase tank 9-2. The inlets of the first DMF-containing aqueous phase tank and the third trichloroethane phase tank 8-2 are respectively connected to the outlet of the first washing chamber 8, and the inlets of the second DMF-containing aqueous phase tank 9-1 and the fourth trichloroethane phase tank 9-2 are respectively connected to the outlet of the second washing chamber 9.

[0088] The processing apparatus provided by the present invention includes a distillation unit, which includes a trichloroethane distillation unit and a DMF distillation unit.

[0089] In this invention, the trichloroethane distillation unit includes: a trichloroethane distillation column 10 connected to the trichloroethane outlet of the first water washing chamber 8; and a trichloroethane distillation condenser 11 whose inlet is connected to the top outlet of the trichloroethane distillation column 10. In this invention, the inlet of the trichloroethane distillation column 10 is preferably connected to the outlet of the third trichloroethane phase tank 8-2.

[0090] In this invention, the trichloroethane distillation condenser 11 preferably includes a first trichloroethane distillation condenser 11-1 and a second trichloroethane distillation condenser 11-2. The inlet of the first trichloroethane distillation condenser 11-1 is connected to the top outlet of the trichloroethane distillation column 10, and the outlet of the first trichloroethane distillation condenser 11-1 is connected to the inlet of the second trichloroethane distillation condenser 11-2.

[0091] In this invention, the trichloroethane distillation unit preferably further includes a trichloroethane product tank 12 and a residual liquid transfer tank 13. The inlet of the trichloroethane product tank 12 is connected to the outlet of the trichloroethane distillation condenser 11, and the inlet of the residual liquid transfer tank 13 is connected to the residual liquid outlet of the trichloroethane distillation column 10.

[0092] In this invention, the DMF distillation unit includes a DMF distillation column 14 whose inlet is connected to the DMF outlet of the first layered tank 3, the DMF outlet of the second layered tank 6, the aqueous phase outlet of the first water washing chamber 8, and the aqueous phase outlet of the second water washing chamber 9, respectively. Preferably, the inlet of the DMF distillation column 14 is connected to the outlet of the first DMF phase tank 3-1, the outlet of the second DMF phase tank 6-1, the outlet of the first DMF-containing aqueous phase tank 8-1, and the outlet of the second DMF-containing aqueous phase tank 9-1, respectively.

[0093] In this invention, the distillation unit preferably further includes a tetramethylurea distillation unit; the tetramethylurea distillation unit includes: a tetramethylurea distillation column 15; a tetramethylurea distillation condenser 16 whose inlet is connected to the top outlet of the tetramethylurea distillation column 15; and a tetramethylurea recovery tank 17 whose inlet is connected to the outlet of the tetramethylurea distillation condenser 16. In this invention, the distillation column is equipped with a reboiler 14-1. In this invention, the inlet of the tetramethylurea distillation column 15 is preferably connected to the outlet of the residual liquid transfer tank 13 via a third vacuum pump 19-1.

[0094] In this invention, the tetramethylurea distillation unit preferably further includes a reflux tank 17-1, a residual liquid recovery tank 17-2, a buffer tank 18-1, a final residual liquid tank 18-2, a fourth vacuum pump 19-2, a fifth vacuum pump 19-3, and a sixth vacuum pump 19-4. The inlet of the reflux tank 17-1 is connected to the outlet of the tetramethylurea distillation condenser 16, the top outlet of the reflux tank 17-1 is connected to the inlet of the buffer tank 18-1, and the bottom outlet of the reflux tank 18-1 is connected to the inlet of the fifth vacuum pump 19-3. The outlet of the fifth vacuum pump 19-3 is connected to both the reflux inlet and the inlet of the residual liquid recovery tank of the tetramethylurea distillation column 15. The outlet of the buffer tank 18-1 is connected to the inlet of the sixth vacuum pump 19-4. The inlet of the final residual liquid tank 18-2 is connected to the bottom outlet of the tetramethylurea distillation column 15 via the fourth vacuum pump 19-2.

[0095] The following is combined Figure 1 A detailed explanation of the treatment method for the chlorination neutralization solution of sucralose-6-ester is provided:

[0096] (1) The chlorinated neutralized liquid of sucralose-6-ester stored in the chlorination neutralization liquid storage tank 1-5 is transferred to the first pre-concentration tank 1-1-1. The chlorinated neutralized liquid flows through the overflow pipe into the second pre-concentration tank 1-1-2 for primary pre-concentration, yielding pre-concentrated residue and primary pre-concentrated gas phase. The primary pre-concentrated gas phase is transferred to the pre-concentration tower 1-2 for secondary pre-concentration under the action of the first heater 1-2-1, and then undergoes primary condensation in the first pre-concentration condenser 2-1, followed by secondary condensation in the second pre-concentration condenser 2-2, yielding pre-concentrated condensed gas phases respectively. The mixture consists of trichloroethane and a pre-concentrated condensate. The pre-concentrated condensate is then transported to a first stratification tank 3 for stratification, resulting in a first DMF light phase and a first trichloroethane heavy phase. The first DMF light phase enters the first DMF phase tank 3-1, and the first trichloroethane heavy phase enters the first trichloroethane phase tank 3-2. A portion of the first trichloroethane heavy phase is refluxed to the pre-concentration tower 1-2 for circulation and secondary pre-concentration. The pre-concentrated condensate gas phase is then pumped into a first separation tank 1-5 via a first vacuum pump 1-6. The pre-concentrated residue is collected and sent to a concentration reactor 1-4 for further processing.

[0097] (2) The first trichloroethane heavy phase is fed into distillation column 4 and distilled under the action of the second heater 4-1 to obtain distilled gas phase and distilled residue. The distilled gas phase is condensed for the third time by the first distillation condenser 5-1 and then condensed for the fourth time by the distillation condenser 5-2 to obtain distilled condensate and distilled condensed gas phase. The distilled condensate is separated into two phases by the second separation tank 6 to obtain the second DMF light phase and the second trichloroethane heavy phase. The second DMF light phase enters the second DMF phase tank 6-1, and the second trichloroethane heavy phase enters the second trichloroethane phase tank 6-2. Part of the second trichloroethane heavy phase is refluxed back into the distillation column 4. The qualified second trichloroethane heavy phase (trichloroethane purity above 99.5%) is fed into the finished product tank 6-3. The distilled condensed gas phase enters the second separation tank 5-3 by the second vacuum pump 5-4.

[0098] (3) The second trichloroethane heavy phase located in the finished product tank 6-3 is transported to the first water washing chamber 8-1 for the first water washing, and the first DMF-containing aqueous phase and the third trichloroethane heavy phase are obtained respectively. The first DMF-containing aqueous phase enters the first DMF-containing aqueous phase tank 8-1, and the third trichloroethane heavy phase enters the third trichloroethane phase tank 8-2.

[0099] (4) The distillation residue is separated into layers in the layering vessel 7. The lower phase is washed with water in the second water washing chamber 9 to obtain the second DMF-containing aqueous phase and the fourth trichloroethane heavy phase. The second DMF-containing aqueous phase enters the second DMF-containing aqueous phase tank 9-1, and the fourth trichloroethane heavy phase enters the fourth trichloroethane phase tank 9-2.

[0100] (5) The first DMF light phase, the second DMF light phase, the first DMF-containing aqueous phase and the second DMF-containing aqueous phase are transported to a DMF distillation column for distillation to obtain the DMF product;

[0101] (6) The third and fourth trichloroethane heavy phases are fed to the trichloroethane distillation column 10 for distillation to obtain trichloroethane gas phase and distillation residue, respectively; the trichloroethane gas phase is condensed in the fifth condenser of the first trichloroethane distillation condenser 11-1 and in the sixth condenser of the second trichloroethane distillation condenser 11-2, and the resulting condensate is the trichloroethane product, which is collected into the trichloroethane product tank;

[0102] (7) The distillation residue is transported to the tetramethylurea distillation column 15 via the residue transfer tank 13. Distillation is carried out under the action of the reboiler 15-1 to obtain a gas phase and a distillation residue. The gas phase is condensed by the tetramethylurea distillation condenser 16 and then enters the reflux tank 17-1. When the liquid level in the reflux tank 17-1 is 30-40% of the volume, the pipe at the bottom of the reflux tank 17-1 flowing to the tetramethylurea distillation column 15 is opened. When the purity of tetramethylurea is above 90%, it is collected as recovered tetramethylurea and sent to the recovery residue tank 17-2, and then enters the tetramethylurea recovery tank 17. The distillation residue is collected to the final residue tank 18-2 as fuel.

[0103] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0104] In the following examples, the composition of the chlorination neutralization solution of sucralose-6-ester (hereinafter referred to as the chlorination neutralization solution) is shown in Table 1:

[0105] Table 1 shows the composition of the neutralized liquid.

[0106]

[0107] Before processing the chlorination neutralization solution, first check the sealing of the processing device. Close the feed valves and vent valves of the first pre-concentration vessel 1-1-1 and the second pre-concentration vessel 1-1-2. Check the valves of the vacuum pump system. Half an hour before starting the processing, turn on all vacuum pumps, with the vacuum pump inlet and outlet fully open. When the vacuum reaches -90 to -95 kPa or higher and no longer rises, close the vacuum pump inlet and then stop the pump. When the feed starts, first observe whether there is any change in the vacuum degree. Only after confirming that the vacuum degree of the processing device remains unchanged should the chlorination neutralization solution processing operation begin.

[0108] Example 1

[0109] use Figure 1 The processing device shown performs the processing, and the specific steps are as follows:

[0110] (1) Add 8400L of chlorination neutralization solution to the chlorination neutralization solution storage tank 1-5, and transport the chlorination neutralization solution to the overflow port in the middle of the first pre-concentration vessel 1-1-1. Turn on the pre-concentration vacuum pump 1-6. When the temperature of the pre-concentration vessel stabilizes at 45~50℃ and the pressure stabilizes at -90~95kPa, the chlorination neutralization solution stored in the chlorination neutralization solution storage tank 1-5 is then transported at a rate of 4m 3The flow rate of / h is delivered to the first pre-concentration vessel 1-1-1, and the chlorinated neutralization liquid enters the second pre-concentration vessel 1-1-2 through the overflow pipe for primary pre-concentration, to obtain pre-concentrated residual liquid and primary pre-concentrated gas phase;

[0111] The primary pre-concentrated gas phase is then... (7-8m) 3 A flow rate of [amount] / h is fed into pre-concentration tower 1-2, where secondary pre-concentration is carried out under the action of the first heater 1-2-1 to obtain secondary pre-concentrated gas phase (5000 kg). The top temperature of pre-concentration tower 1-2 is 30–33℃, the middle temperature is 35–38℃, and the bottom temperature is 38–40℃. The top temperature is controlled by heavy phase reflux (reflux flow rate 0.3–0.5 m³ / h). 3 The liquid level in the pre-concentration tower 1-2 is controlled by 95℃ hot water as the heat source. After the liquid level reaches 60% of the volume, it is pumped to the neutralization liquid transfer vessel.

[0112] The secondary pre-concentrated gas phase is then... 3 The flow rate of / h is sampled and sent to the first pre-concentrating condenser 2-1 for first condensation (30-40℃), and then sent to the second pre-concentrating condenser 2-2 for second condensation (15-25℃), to obtain pre-concentrated condensed gas phase and pre-concentrated condensate liquid respectively;

[0113] The pre-concentrated condensate is transported to the first stratification tank 3 for stratification, resulting in a first DMF light phase and a first trichloroethane heavy phase. The first DMF light phase enters the first DMF phase tank 3-1, and the first trichloroethane heavy phase enters the first trichloroethane phase tank 3-2. The 8-10 v / v% of the first trichloroethane heavy phase is refluxed to the pre-concentration tower 1-2 for circulation and secondary pre-concentration. The pre-concentrated condensate enters the first separation tank 1-5 under the action of the first vacuum pump 1-6. The pre-concentrated residue is collected to the concentration reactor 1-4 for further processing. When the pre-concentrated condensate is not clear (bumping occurs), it needs to be pre-concentrated again. The material inlet and outlet are adjusted according to the rise in the liquid level in the first stratification tank 3. The entire pre-concentration process should be stable, and the pre-concentration speed should be strictly controlled and uniform. Distillation should not be too fast, and material rushing is strictly prohibited. The temperature of the liquid (trichloroethane) should be controlled not to exceed 25-30℃.

[0114] (2) The first trichloroethane was rephased at 6.5-7m 3 A flow rate of [amount] m³ / h is fed into distillation column 4, where distillation is carried out under the action of the second heater 4-1, yielding distilled gas and distilled residue. The top temperature of distillation column 4 is 45–55℃, and the top vacuum is -85–-92 kPa. The distilled gas outflow rate is 4–5 m³ / h. 3 / h;

[0115] The distilled vapor phase undergoes a third condensation (30-40°C) in the first distillation condenser 5-1, and then a fourth condensation (15-20°C) in the distillation condenser 5-2, to obtain distilled condensate and distilled condensed vapor phase;

[0116] The distillation condensate is separated into two phases in the second separation tank 6, resulting in a second DMF light phase and a second trichloroethane heavy phase. The second DMF light phase enters the second DMF phase tank 6-1, and the second trichloroethane heavy phase enters the second trichloroethane phase tank 6-2. The second trichloroethane heavy phase with 8-10 v / v% is refluxed to the distillation column 4. The qualified second trichloroethane heavy phase (trichloroethane purity above 99.6%) is transported to the finished product tank 6-3. The distillation condensate gas phase (trichloroethane) enters the second separation tank 5-3 via the second vacuum pump 5-4.

[0117] (3) The second trichloroethane heavy phase located in the finished product tank 6-3 is transported to the first water washing chamber 8-1 for the first water washing, to obtain the first DMF-containing aqueous phase and the third trichloroethane heavy phase respectively. The first DMF-containing aqueous phase enters the first DMF-containing aqueous phase tank 8-1, and the third trichloroethane heavy phase enters the third trichloroethane phase tank 8-2; wherein, the volume ratio of the second trichloroethane heavy phase to the water used for washing is 1:0.5;

[0118] (4) The distillation residue is separated into layers in the layering vessel 7. The lower phase is mixed with pure water in the second water washing chamber 9 and washed to obtain a second DMF-containing aqueous phase and a fourth trichloroethane heavy phase. The second DMF-containing aqueous phase enters the second DMF-containing aqueous phase tank 9-1, and the fourth trichloroethane heavy phase enters the fourth trichloroethane phase tank 9-2. The volume ratio of the lower phase to the water used for washing is 1:0.5.

[0119] (5) The first DMF light phase, the second DMF light phase, the first DMF-containing aqueous phase, and the second DMF-containing aqueous phase are fed to a DMF distillation column for distillation to obtain DMF product; wherein, the top temperature of the DMF distillation column is 95±5℃, the middle temperature is 100±5℃, the bottom temperature is 106±5℃, and the pressure is -0.088±0.005MPa; the purity of the distilled DMF is ≥99.50%, and the DMF content in the bottom water is ≤0.1wt%.

[0120] (6) The third and fourth heavy phases of trichloroethane are fed to the trichloroethane distillation column 10 for distillation to obtain trichloroethane gas phase and distillation residue, respectively; the trichloroethane gas phase is condensed in the fifth condenser (30-40℃) of the first trichloroethane distillation condenser 11-1 and in the sixth condenser (15-20℃) of the second trichloroethane distillation condenser 11-2 to obtain the trichloroethane product (trichloroethane purity ≥99.5%), which is collected into the trichloroethane product tank; wherein, the top temperature of the distillation column 10 is 50±5℃, the middle temperature is 65±5℃, the bottom temperature is 78±5℃, and the pressure is -0.093±0.003MPa;

[0121] (7) The distillation residue (containing 60-80 wt% tetramethylurea) is transported to the tetramethylurea distillation column 15 via the residue transfer tank 13. Distillation is carried out under the action of the reboiler 15-1, yielding a vapor phase and a distillation residue. The vapor phase is condensed (25-30°C) by the tetramethylurea distillation condenser 16 and then enters the reflux tank 17-1. When the reflux tank 17-1 has a liquid level of 30-40% of its volume, the pipe flowing from the bottom of the reflux tank 17-1 to the tetramethylurea distillation column 15 is opened, controlling 20% ​​of the liquid in the reflux tank 17-1 to flow back to the tetramethylurea distillation column 15. When the purity of the tetramethylurea is above 90%, it is used as recovered tetramethylurea at a concentration of 1-1.5 m³. 3 The distillation residue is collected at a flow rate of / h into the residual liquid recovery tank 17-2, and then enters the tetramethylurea recovery tank 17; the distillation residue is discharged at a flow rate of 0.5-0.8m 3 The flow rate is collected at a rate of / h and deposited into the final residual liquid tank 18-2 as fuel; among which, the reflux flow rate at the top of the methylurea distillation column 15 is 1.5-2m³ / h. 3 / h, the top temperature of the column is 70~75℃, the bottom temperature of the column is 105~115℃, the pressure is -88~-95kPa, and the top vacuum degree is -90~-95kPa.

[0122] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for treating a chlorinated neutralization solution of sucralose-6-ester, characterized in that, Includes the following steps: (1) The chlorinated neutralized solution of sucralose-6-ester is subjected to pre-concentration, condensation and separation in sequence to obtain a first DMF light phase and a first trichloroethane heavy phase, respectively; the pressure of the pre-concentration is -90 to -95 kPa; the pre-concentration includes a first-stage pre-concentration and a second-stage pre-concentration in sequence, the temperature of the first-stage pre-concentration is 45 to 50°C and the temperature of the second-stage pre-concentration is 30 to 40°C; the condensation includes a first-stage condensation and a second-stage condensation in sequence, the temperature of the first-stage condensation is 30 to 40°C and the temperature of the second-stage condensation is 15 to 25°C; (2) The first trichloroethane heavy phase is distilled to obtain a distilled gas phase and a distillation residue; the distilled gas phase is condensed and separated into two phases to obtain a second DMF light phase and a second trichloroethane heavy phase; the distillation temperature is 45-55℃ and the vacuum degree is -85--92kPa; the condensation includes a third condensation and a fourth condensation in sequence, the temperature of the third condensation is 30-40℃ and the temperature of the fourth condensation is 15-25℃; (3) The second trichloroethane heavy phase is washed with water to obtain the first DMF-containing aqueous phase and the third trichloroethane heavy phase, respectively; (4) The distillate residue is separated into layers, and the lower phase is washed with water to obtain a second aqueous phase containing DMF and a fourth heavy phase containing trichloroethane. (5) The first DMF light phase, the second DMF light phase, the first DMF-containing aqueous phase and the second DMF-containing aqueous phase are distilled to obtain the DMF product; (6) The third and fourth trichloroethane heavy phases are subjected to distillation to obtain trichloroethane product and distillation residue, respectively; the distillation temperature is 60-83℃ and the vacuum degree is -93±3kPa. (7) The distillate obtained in step (6) is distilled using the residual liquid to obtain recovered tetramethylurea; Steps (3) and (4) have no chronological order; Steps (5) and (6) are not in any particular order.

2. The processing method according to claim 1, characterized in that, In step (1), a portion of the first trichloroethane is recycled in a rephase cycle for the secondary pre-concentration.

3. The processing method according to claim 1, characterized in that, In step (2), the ratio of the feed flow rate of the first trichloroethane heavy phase to the output flow rate of the distilled gas phase is 6.5-7:4-5; The distillation is carried out in part by a second trichloroethane rephase cycle.

4. The processing method according to claim 1, characterized in that, In step (5), the distillation temperature is 95-111℃ and the vacuum degree is -88±5kPa.

5. The apparatus for treating the chlorinated neutralized solution of sucralose-6-ester used in the treatment method according to any one of claims 1 to 4, characterized in that, According to the material flow sequence, it includes a pre-concentration unit, a distillation unit, a water washing unit, a rectification unit, and a tetramethylurea rectification unit connected in sequence; The pre-concentration unit includes: a pre-concentrator (1); a pre-concentration condenser (2) whose inlet is connected to the outlet of the pre-concentrator (1); a first stratification tank (3) whose inlet is connected to the outlet of the pre-concentration condenser (2), wherein the trichloroethane outlet of the first stratification tank (3) is connected to the reflux inlet of the pre-concentration condenser (2); the pre-concentrator (1) includes a plurality of pre-concentration kettles (1-1), and a pre-concentration tower (1-2) whose inlet is connected to the outlet of the plurality of pre-concentration kettles (1-1) respectively, wherein the pre-concentration tower (1-2) is provided with a first heater (1-2-1); The distillation unit includes: a distillation column (4), the inlet of which is connected to the trichloroethane outlet of the first layering tank (3), and the distillation column (4) is equipped with a second heater (4-1); a distillation condenser (5) whose inlet is connected to the gas phase outlet of the distillation column (4); a second layering tank (6) whose inlet is connected to the outlet of the distillation condenser (5), and the trichloroethane outlet of the second layering tank (6) is connected to the reflux inlet of the distillation column (4); and a layering vessel (7) whose inlet is connected to the bottom outlet of the distillation column (4). The water washing unit includes: a first water washing chamber (8) whose inlet is connected to the trichloroethane outlet of the second layering tank (6); and a second water washing chamber (9) whose inlet is connected to the outlet of the layering vessel (7), the second water washing chamber (9) being provided with a water inlet; The distillation unit includes a trichloroethane distillation unit and a DMF distillation unit; The trichloroethane distillation unit includes: a trichloroethane distillation column (10) connected to the trichloroethane outlet of the first washing chamber (8) and the trichloroethane outlet of the second washing chamber (9); and a trichloroethane distillation condenser (11) whose inlet is connected to the top outlet of the trichloroethane distillation column (10). The DMF distillation unit includes a DMF distillation column (14) whose inlet is connected to the DMF outlet of the first layered tank (3), the DMF outlet of the second layered tank (6), the aqueous phase outlet of the first water washing chamber (8), and the aqueous phase outlet of the second water washing chamber (9), respectively. The tetramethylurea distillation unit includes: a tetramethylurea distillation column (15); and a tetramethylurea distillation condenser (16) whose inlet is connected to the top outlet of the tetramethylurea distillation column (15).

6. The processing apparatus according to claim 5, characterized in that, The pre-concentration condenser (2) includes a first pre-concentration condenser (2-1), a second pre-concentration condenser (2-2) whose inlet is connected to the outlet of the first pre-concentration condenser (2-1), and the reflux inlet of the second pre-concentration condenser (2-2) is connected to the trichloroethane outlet of the first stratification tank (3).

7. The processing apparatus according to claim 5, characterized in that, The distillation condenser (5) includes a first distillation condenser (5-1) and a second distillation condenser (5-2) whose inlet is connected to the outlet of the first distillation condenser (5-1).

8. The processing apparatus according to claim 5, characterized in that, The trichloroethane distillation condenser (11) includes a first trichloroethane distillation condenser (11-1) and a second trichloroethane distillation condenser (11-2) whose inlet is connected to the outlet of the first trichloroethane distillation condenser (11-1); The trichloroethane distillation unit also includes a trichloroethane product tank (12) and a residual liquid transfer tank (13). The inlet of the trichloroethane product tank (12) is connected to the outlet of the trichloroethane distillation condenser (11), and the inlet of the residual liquid transfer tank (13) is connected to the residual liquid outlet of the trichloroethane distillation column (10). The tetramethylurea distillation unit also includes a tetramethylurea recovery tank (17) whose inlet is connected to the outlet of the tetramethylurea distillation condenser (16).

Images