An apparatus and method for chlorinating sucralose with built-in continuous heating

Abstract

This invention discloses an apparatus and method for continuous heating of sucralose chlorination, comprising a continuous heating tower and a condenser. The continuous heating tower has a bottom vessel and an upper condenser tube assembly. A heater is built into the upper part of the bottom vessel, and a cavity section is formed between the heater and the condenser tube assembly. The condenser tube assembly has a shell-side inlet at the upper end and a shell-side outlet at the lower end. The cavity section has a feed inlet and a liquid phase inlet. The gas outlet at the top of the continuous heating tower is connected to the condenser inlet, the liquid phase outlet of the condenser is connected to the liquid phase inlet of the cavity section, and the shell-side outlet is connected to the feed inlet. A steam jacket is provided outside the bottom vessel, and the steam-water outlet of the heater is connected to the steam-water inlet of the steam jacket. The apparatus and method of this invention not only fully utilize the heat and refrigeration capacity of the material itself, saving a significant amount of steam and refrigeration input, but also achieve continuous operation of the high-temperature chlorination section in sucralose production, eliminating the need for intermittent waiting during the heating process.

Description

Technical Field

[0001] This invention relates to sucralose production technology, specifically to a device and method for sucralose chlorination with built-in continuous heating. Background Technology

[0002] In the production of sucralose, the high-temperature chlorination process often employs a batch production process using glass-lined reactors, such as... Figure 1 As shown, firstly, a certain proportion of trichloroethane and thionyl chloride are added to the low-temperature chlorination reactor. -20°C brine is then circulated into the reactor jacket to control the temperature of the material inside the reactor below 5°C. Then, an esterification solution (DMF solution of sucrose-6-ethyl ester) is added dropwise, controlling the dropping rate so that the temperature inside the low-temperature chlorination reactor does not exceed 5°C. This causes a Werthall reaction to produce Werthall salt, as shown in the following formula:

[0003]

[0004] The reaction of sucrose esters with Werthall salts produces sucrose-6-ethyl ester-O-alkyl chloride, as shown in the following formula:

[0005]

[0006] After the low-temperature chlorination reaction is completed, the low-temperature chlorination liquid flows into the high-temperature chlorination reactor. Steam is introduced into the jacket of the high-temperature chlorination reactor to control the stepwise heating of the liquid and maintain the temperature. The reaction produces sucralose-6-ethyl ester-O-alkyl chloride, as shown in the following formula:

[0007]

[0008] Currently, most industrial production workshops use a 12-hour high-temperature chlorination process (heating to 112°C for 10 hours and then holding for 2 hours) or a 7-hour high-temperature chlorination process (heating to 112°C for 5 hours and then holding for 2 hours). This intermittent production is time-consuming and requires a lot of equipment. It is mainly limited by the glass-lined reactor, which relies on the jacketed steam heating of the glass-lined reactor. Its heat conduction rate and heat transfer area are relatively small.

[0009] The approximate composition of one batch of raw material liquid in the production workshop is shown in Table 1. This 20.8 tons of liquid needs to be evenly distributed into two 12.5m³ medium-low temperature chlorination reactors.

[0010] Table 1

[0011]

[0012] Currently, the daily feed rate in the industrial production workshop is 24 batches, with a raw material liquid mass of 499.2 tons. Each reactor contains 10.4 tons. Assuming that each batch of high-temperature chlorination takes 10 hours, the minimum number of high-temperature chlorination reactors required is: 499.2 × 10 ÷ 10.4 ÷ 24 = 20 units.

[0013] Therefore, the existing batch production in glass-lined reactors has drawbacks such as numerous equipment, high energy consumption (mainly steam and electricity), and long production cycles.

[0014] The applicant's experiments revealed that a high yield could also be obtained by heating to 118°C for 1 hour and holding at that temperature for 1.5 hours. The shorter the reaction time, the more likely it is to achieve a continuous high-temperature chlorination process.

[0015] In summary, developing new equipment to accelerate the mass and heat transfer rate of the chlorination reaction can solve the drawbacks of batch production in glass-lined reactors.

[0016] Patent application number 202011365527.6 discloses a method and apparatus for continuous high-temperature reaction of sucralose. This patent uses three high-temperature chlorination reaction towers connected in series and three reboilers to achieve continuous high-temperature reaction through a "relay" heating method. However, this patent still has the following problems:

[0017] 1. The reaction equipment is extensive, requiring three reboilers, three reaction towers, and auxiliary equipment connected in series;

[0018] 2. High energy consumption: the low-temperature chlorination liquid requires heating in reboiler #1, and the trichloroethane vaporized needs to be condensed and refluxed.

[0019] 3. This patent does not achieve continuous production. The low-temperature chlorination liquid enters the No. 1 high-temperature chlorination reaction tower and is heated for 30 minutes to obtain solution A. Then it enters the No. 2 high-temperature chlorination reaction tower and is heated for 60 minutes to obtain solution B. Then it enters the No. 3 high-temperature chlorination reaction tower and is heated for 120 minutes to obtain solution C. The heating time of each tower is different and increases sequentially. Therefore, continuous production cannot be achieved.

[0020] 4. Trichloroethane vapor, hydrogen chloride, and sulfur dioxide all go to the external condenser of the tower. The material flow rate is large, so the pipeline equipment will be relatively large. The composition of a batch of high-temperature chlorination liquid in the production workshop is shown in Table 2. Trichloroethane accounts for the largest proportion in the gas phase.

[0021] Table 2

[0022]

[0023] With a feed rate of 20.8 tons / hour, the per-hour vaporization rate is 14.8 tons of trichloroethane, 0.9 tons of hydrogen chloride, and 1.7 tons of sulfur dioxide, resulting in a trichloroethane mass fraction of 85%. Assuming a volume of 22.4 liters per mole, the gas flow rates are shown in Table 3.

[0024] Table 3

[0025]

[0026] The gas velocity inside the pipeline must be less than 5 m / s; otherwise, excessively high gas velocity can easily entrain materials, causing losses. Therefore, the minimum diameter of the pipeline and condenser is calculated as follows: Therefore, the condensers #1, #2, and #3 in this patent, as well as their respective gas phase pipes connecting to the top of the tower, will be relatively large.

[0027] If some of the trichloroethane can be condensed and refluxed in advance inside the tower, the gas flow rate to the condenser outside the tower will be reduced, and the diameter of the pipes and condenser can be significantly reduced, thereby reducing equipment investment.

[0028] In view of the above problems, we have developed a device and method for continuous heating of sucralose chlorination with an internal heating element. The reboiler, heater, and condenser tubes are integrated into one unit. The condenser tubes enable heat exchange between the trichloroethane gas phase and the low-temperature chlorination liquid. The secondary steam discharged from the heater further heats the reboiler. Therefore, the low-temperature chlorination liquid undergoes three heating processes within the same device: heating via the trichloroethane gas phase, heating via the heater, and heating via the reboiler. This stepwise temperature increase avoids the carbonization phenomenon that occurs when directly heating to above 112°C. Furthermore, the low temperature of the chlorination liquid effectively cools the trichloroethane gas phase, thus saving significant refrigeration costs compared to existing technologies. Summary of the Invention

[0029] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a device and method for chlorinating sucralose with built-in continuous heating.

[0030] To achieve the above objectives, the technical solution of the present invention is: a device for continuous heating of sucralose chlorination, characterized in that: it includes a continuous heating tower and a condenser; the lower end of the continuous heating tower is a tower bottom; a tubular heater is built into the upper end of the tower bottom; a condensing tube is built into the upper part of the continuous heating tower; a cavity section is formed between the heater and the condensing tube; the condensing tube has a shell-side inlet at the upper end and a shell-side outlet at the lower end; a feed inlet is located at the center of the cavity section; a liquid phase inlet is located above the feed inlet; the gas outlet at the top of the continuous heating tower is connected to the condenser inlet via a pipeline; the gas phase outlet of the condenser is connected to a tail gas treatment pipeline; the liquid phase outlet is connected to the liquid phase inlet of the cavity section via a pipeline; the shell-side outlet is connected to the feed inlet via a pipeline; a steam jacket is provided outside the tower bottom; a collection outlet is provided at the bottom of the tower; the heater has a steam inlet and a steam-water outlet; the steam-water outlet is connected to the steam-water inlet of the steam jacket via a pipeline.

[0031] Furthermore, the bottom of the tower is provided with a circulation outlet, and the cavity section is provided with a circulation inlet at the lower end of the feed inlet. The circulation outlet is connected to the circulation inlet through a pipeline, and the connecting pipeline of the circulation outlet is provided with at least one circulation pump, a second flow meter, and a second thermometer.

[0032] Furthermore, the continuous heating tower is equipped with a first differential pressure level gauge at the top of the upper tube sheet of the heater and a second differential pressure level gauge at the height of the circulation inlet.

[0033] Furthermore, the shell-side inlet is connected to a feed pipeline, and the feed pipeline is equipped with at least one feed pump. A first flow meter and a first thermometer are provided between the feed pump and the shell-side inlet.

[0034] Furthermore, a fifth thermometer is installed on the connecting pipeline between the shell outlet and the feed inlet, a fourth thermometer is installed on the connecting pipeline of the top gas outlet of the continuous heating tower, and a sixth thermometer is installed on the connecting pipeline of the liquid phase outlet of the condenser.

[0035] Furthermore, the bottom outlet of the tower is connected to a downstream device via a pipeline, and the pipeline connecting the bottom outlet is equipped with a third flow meter, a third thermometer, and at least one extraction pump.

[0036] Another technical solution of the present invention is: a method for chlorinating sucralose with an internal continuous heating system, characterized by comprising the following steps:

[0037] (1) The feed pump delivers the low-temperature chlorinated liquid from the low-temperature chlorination section to the inlet of the shell side of the condenser tube. The low-temperature chlorinated liquid enters the shell side of the condenser tube and is heated by the rising trichloroethane gas phase during the descent process in the shell side of the condenser tube. After the first heating is completed, it flows out from the shell side outlet of the condenser tube and enters the cavity section through the feed port.

[0038] (2) The chlorinated liquid entering the cavity section falls into the tube side of the heater under the action of gravity, is heated by the steam in the tube side of the heater, and enters the tower after completing the second heating.

[0039] (3) The steam in the heater tube flows out through the steam water outlet and then enters the steam jacket of the tower bottom through the steam water inlet to heat the tower bottom. The chlorination liquid entering the tower bottom completes the third heating in the tower bottom.

[0040] (4) Part of the high-temperature chlorination liquid in the tower is transported to the circulation inlet through the circulation pump and enters the cavity section. Under the action of gravity, it falls into the tube side of the heater to achieve circulation heating; the other part is extracted through the extraction outlet and transported to the downstream unit through the extraction pump.

[0041] (5) After the chlorinated liquid is heated in the continuous heating tower, the trichloroethane vaporizes and rises into the cavity section, and then continues to rise into the shell side of the condenser tube. It is condensed and liquefied by the low temperature chlorinated liquid in the shell side of the condenser tube, and then falls back into the tower under the action of gravity. A small part of the uncondensed trichloroethane gas phase enters the condenser for condensation and liquefaction. After liquefaction, it is discharged from the liquid phase outlet and flows into the continuous heating tower through the liquid phase inlet. The uncondensed gas phase enters the tail gas treatment pipeline through the gas phase outlet.

[0042] Furthermore; in step (1), the temperature of the low-temperature chlorine liquid delivered to the shell-side inlet of the condenser tube is 5°C, and the temperature of the chlorine liquid flowing out from the shell-side outlet of the condenser tube after the first heating is 79-82°C; in step (4), the temperature of the high-temperature chlorine liquid delivered to the circulation inlet by the circulation pump is 116-119°C; and in step (5), the temperature of the trichloroethane liquid phase discharged from the liquid phase outlet of the condenser is 45-51°C.

[0043] Furthermore, the combined flow rate of the extraction pump and the condenser vapor outlet flow rate are balanced with the flow rate of the feed pump.

[0044] Furthermore, the material liquid level in the cavity section is near the middle position between the upper tube sheet of the heater and the circulation inlet. The material liquid level (L) is measured by the first differential pressure level gauge and the second differential pressure level gauge. The liquid level range is 1m, and L fluctuates between 0.2m and 0.8m.

[0045] The beneficial effects of this invention are as follows: The built-in continuous heating device for sucralose chlorination of this invention integrates the tower bottom, heater, and condenser tubes into one unit. The condenser tubes enable heat exchange between the trichloroethane gas phase and the low-temperature chlorination liquid. The secondary steam discharged from the heater further heats the tower bottom. Therefore, the low-temperature chlorination liquid undergoes three heating processes within the continuous heating tower: heating via the trichloroethane gas phase, heating via the heater, and heating via the tower bottom. This stepwise temperature increase avoids the carbonization phenomenon that occurs when directly heating to above 112°C. Furthermore, the low temperature of the low-temperature chlorination liquid effectively cools the trichloroethane gas phase. Therefore, compared with existing technologies, the device and method of this invention not only fully utilize the heat and cooling capacity of the material itself, saving significant amounts of steam and refrigeration inputs, but also achieve continuous operation of the high-temperature chlorination section in sucralose production, eliminating the need for intermittent waiting during the heating process.

[0046] Because some of the trichloroethane gas phase is condensed and refluxed in the condenser tube section, the gas flow rate to the condenser outside the tower is reduced. This allows for a significant reduction in the pipe diameter of the gas outlet pipeline at the top of the continuous heating tower and the diameter of the condenser, thereby reducing equipment investment. Attached Figure Description

[0047] Figure 1 This is a structural diagram of the prior art in the background section;

[0048] Figure 2 This is a schematic diagram of the structure of the present invention;

[0049] Figure 2In the middle section: 1. Continuous heating tower; 2. Condenser; 3. Tower bottom; 4. Heater; 5. Condensation tubes; 6. Cavity section; 7. Shell side inlet; 8. Shell side outlet; 9. Feed inlet; 10. Liquid phase inlet; 11. Tail gas treatment pipeline; 12. Steam jacket; 13. Circulation inlet; 14. Circulation outlet; 15. Outlet; 16. First differential pressure level gauge; 17. Second differential pressure level gauge; 18. Feed pump; 19. Outlet pump; 20. Circulation pump; F01. First flow meter; TO1. First thermometer; F02. Second flow meter; TO2. Second thermometer; F03. Third flow meter; TO3. Third thermometer; TO4. Fourth thermometer; TO5. Fifth thermometer; TO6. Sixth thermometer. Detailed Implementation

[0050] Example 1:

[0051] like Figure 2 As shown, a device for continuous heating of sucralose chlorination includes a continuous heating tower 1 and a condenser 2. The lower end of the continuous heating tower 1 is a reboiler 3. A tubular heater 4 is built into the upper end of the reboiler 3. A condensing tube 5 is built into the upper part of the continuous heating tower 1. A cavity section 6 is formed between the heater 4 and the condensing tube 5. The condensing tube 5 has a shell-side inlet 7 at the upper end and a shell-side outlet 8 at the lower end. A feed inlet 9 is located at the center of the cavity section 6. A liquid phase inlet 10 is located above the feed inlet 9. The top of the continuous heating tower 1... The gas outlet is connected to the inlet of condenser 2 via a pipeline. The gas phase outlet of condenser 2 is connected to the tail gas treatment pipeline 11, and the liquid phase outlet is connected to the liquid phase inlet 10 of the cavity section 6 via a pipeline. The shell-side outlet 8 is connected to the feed inlet 9 via a pipeline. A fifth thermometer TO5 is installed on the connecting pipeline between the shell-side outlet 8 and the feed inlet 9. The shell-side inlet 7 is connected to the feed pipeline. Two feed pumps 18 are installed on the feed pipeline. A first flow meter F01 and a first thermometer TO1 are installed between the feed pumps 18 and the shell-side inlet 7. The two feed pumps 18 are connected in parallel.

[0052] The tower 3 is equipped with a steam jacket 12 and a bottom outlet 15. The heater 4 is equipped with a steam inlet and a steam water outlet. The steam water outlet is connected to the steam water inlet of the steam jacket 12 through a pipeline.

[0053] The bottom of the tower 3 is also provided with a circulation outlet 14, and the cavity section 6 is provided with a circulation inlet 13 at the lower end of the feed inlet. The circulation outlet 14 is connected to the circulation inlet 13 through a pipeline. Two circulation pumps 20, a second flow meter F02 and a second thermometer TO2 are provided on the connecting pipeline of the circulation outlet 14. The two circulation pumps 20 are connected in parallel.

[0054] The continuous heating tower 1 is equipped with a first differential pressure level gauge 16 at the top of the tube sheet of the heater 4 and a second differential pressure level gauge 17 at the height of the circulation inlet 13. A fourth thermometer TO4 is installed on the gas outlet connecting pipeline at the top of the continuous heating tower 1. A sixth thermometer TO6 is installed on the liquid phase outlet connecting pipeline of the condenser 2. The bottom outlet 15 of the tower 3 is connected to the downstream device through a pipeline. A third flow meter F03, a third thermometer TO3 and two extraction pumps 19 are installed on the extraction outlet 15 connecting pipeline. The two extraction pumps 19 are connected in parallel.

[0055] Example 2:

[0056] A method for chlorinating sucralose using an internal continuous heating system includes the following steps:

[0057] (1) The feed pump 18 delivers the low-temperature chlorinated liquid from the low-temperature chlorination section to the shell-side inlet 7 of the condenser tube 5. The temperature of the first thermometer T01 is 5℃, and the flow rate of the first flowmeter F01 is 20.8t / h. The low-temperature chlorinated liquid enters the shell-side of the condenser tube 5 and is heated by the rising trichloroethane gas phase during the descent process in the shell-side of the condenser tube 5. After the first heating is completed, it flows out from the shell-side outlet 8 and enters the cavity section 6 through the feed inlet 9. The temperature of the fifth thermometer TO5 is 81℃.

[0058] (2) The chlorinated liquid entering the cavity section 6 falls into the tube side of the heater 4 under the action of gravity, and is heated by the steam in the tube side of the heater 4. After completing the second heating, it enters the tower bottom 3.

[0059] (3) The steam in the tube side of heater 4 flows out through the steam water outlet, and then enters the steam jacket 12 through the steam water inlet of the steam jacket 12 of the tower 3 to heat the tower 3. The chlorinated liquid entering the tower 3 completes the third heating in the tower 3. The material liquid level in the cavity section 6 is near the middle position between the upper tube plate of heater 4 and the circulation inlet 13, and L is 0.5m.

[0060] (4) A portion of the high-temperature chlorination liquid in the bottom of the tower 3 is transported to the circulation inlet 13 by the circulation pump 20 and enters the cavity section 6. Under the action of gravity, it falls into the tube side of the heater 4 to achieve circulation heating. The temperature of the second thermometer T02 is 118℃ and the flow rate of the second flow meter F02 is 39.6t / h. Another portion is extracted through the extraction outlet 15 and transported to the downstream unit by the extraction pump 19. The temperature of the third thermometer T03 is 117℃ and the flow rate of the third flow meter F03 is 18.3t / h.

[0061] (5) After the chlorinated liquid is heated in the continuous heating tower 1, the trichloroethane vaporizes and rises into the cavity section 6, and then continues to rise into the shell side of the condenser tube 5, where it is condensed and liquefied by the low-temperature chlorinated liquid in the shell side of the condenser tube 5. Then, under the action of gravity, it falls back into the tower. A small portion of the uncondensed trichloroethane gas phase enters the condenser 2 from the top outlet of the continuous heating tower 1 and is condensed and liquefied. The temperature of the fourth thermometer T04 is 95°C. After liquefaction, it is discharged from the liquid phase outlet of the condenser 2 and flows into the continuous heating tower 1 through the liquid phase inlet 10. The temperature of the sixth thermometer T06 is 45°C. The uncondensed gas phase enters the tail gas treatment pipeline 11 through the gas phase outlet of the condenser 2 and is transported to the tail gas separation device. The flow rate of the extraction pump 19 plus the flow rate of the gas phase outlet of the condenser 2 is balanced with the flow rate of the feed pump 18. The main components of the uncondensed gas phase are sulfur dioxide and hydrogen chloride gas. After separation and bottling in the tail gas separation device, liquefied high-purity hydrogen chloride product and sulfur dioxide product are obtained.

[0062] Examples 3-4:

[0063] The differences between Examples 3 and 4 and Example 2 are that the flow rate and temperature parameters are different, and the material liquid level is different. The specific parameter values ​​are shown in Table 4.

[0064] Table 4

[0065]

[0066] Example 5:

[0067] Take 765g of the liquid sample collected by pump 19 in Example 4 (49g sucrose equivalent), cool it to 5°C, add ammonia water dropwise to adjust the pH of the liquid sample to 10, continue stirring for 5 minutes, and then add hydrochloric acid dropwise to adjust the pH of the liquid sample to 7. The temperature should not exceed 10°C during the pH adjustment process.

[0068] The pH-adjusted liquid was placed in a rotary evaporator, and trichloroethane, DMF, and water were removed under negative pressure to obtain syrup. An appropriate amount of water was added to dilute the syrup, and the mixture was filtered to obtain 17 grams of solid residue and 370 mL of filtrate. The filtrate was analyzed, as shown in Table 5.

[0069] Table 5

[0070] Liquid chromatography content External standard content Sucralose 1.31％ Sucralose 4.97％ Sucralose 0.61％ 0.91g / L Sucralose 6.85％ Sucralose-6-ethyl ester 58.66％ 91.69g / L

[0071] The mass of sucralose-6-ethyl ester in the filtrate is 91.69 × 0.370 = 33.92 g.

[0072] Yield = 33.92 ÷ 49 = 69.22%.

[0073] Comparative Example 1:

[0074] Take 856g of low-temperature chlorination liquid (49g sucrose equivalent) from the low-temperature chlorination section and place it in a 1000mL four-necked flask. Set the temperature to 5℃, start stirring, and turn on the oil bath heating. Heat the liquid at a constant rate to 112℃ over 10 hours, and then keep it at 112℃ for 2 hours.

[0075] Then cool to 5℃, add ammonia water dropwise to adjust the pH of the solution to 10, continue stirring for 5 minutes, and then add hydrochloric acid dropwise to adjust the pH of the solution to 7. The temperature should not exceed 10℃ during the pH adjustment process.

[0076] The pH-adjusted liquid was placed in a rotary evaporator, and trichloroethane, DMF, and water were removed under negative pressure to obtain syrup. An appropriate amount of water was added to dilute the syrup, and the mixture was filtered to obtain 19g of solid residue and 375mL of filtrate. The filtrate was analyzed, as shown in Table 6.

[0077] Table 6

[0078] Liquid chromatography content External standard content Sucralose 1.66％ Sucralose 5.30％ Sucralose 1.68％ 2.27g / L Sucralose 6.58％ Sucralose-6-ethyl ester 57.87％ 83.07g / L

[0079] The mass of sucralose-6-ethyl ester in the filtrate is 83.07 × 0.375 = 31.15 g.

[0080] Yield = 31.15 ÷ 49 = 63.57%.

[0081] Comparative Example 2:

[0082] Take 515g of low-temperature chlorination liquid (29.5g sucrose equivalent) from the low-temperature chlorination section and put it into a 1000mL four-necked flask. Set the temperature to 5℃, start stirring, and turn on the oil bath heating. Heat the liquid at a constant rate to 112℃ over 5 hours, and then keep it at 112℃ for 2 hours.

[0083] Then cool to 5℃, add ammonia water dropwise to adjust the pH of the solution to 10, continue stirring for 5 minutes, and then add hydrochloric acid dropwise to adjust the pH of the solution to 7. The temperature should not exceed 10℃ during the pH adjustment process.

[0084] The pH-adjusted liquid was placed in a rotary evaporator, and trichloroethane, DMF, and water were removed under negative pressure to obtain syrup. An appropriate amount of water was added to dilute the syrup, and the mixture was filtered to obtain 12g of solid residue and 263mL of filtrate. The filtrate was analyzed, as shown in Table 7.

[0085] Table 7

[0086] Liquid chromatography content External standard content Sucralose 1.56％ Sucralose 5.76％ Sucralose 2.19％ 2.53g / L Sucralose 6.04％ Sucralose-6-ethyl ester 58.69％ 72.12g / L

[0087] The mass of sucralose-6-ethyl ester in the filtrate is 72.12 × 0.263 = 18.97 g.

[0088] Yield = 18.97 ÷ 29.5 = 64.31%.

[0089] Comparative Example 3:

[0090] Take 855g of low-temperature chlorination liquid (49g sucrose equivalent) from the low-temperature chlorination section and place it in a 1000mL four-necked flask. Set the temperature to 5℃, start stirring, and turn on the oil bath heating. Heat the liquid at a constant rate to 118℃ over 1 hour, and then keep it at 118℃ for 1.5 hours.

[0091] Then cool to 5℃, add ammonia water dropwise to adjust the pH of the solution to 10, continue stirring for 5 minutes, and then add hydrochloric acid dropwise to adjust the pH of the solution to 7. The temperature should not exceed 10℃ during the pH adjustment process.

[0092] The pH-adjusted liquid was placed in a rotary evaporator, and trichloroethane, DMF, and water were removed under negative pressure to obtain syrup. An appropriate amount of water was added to dilute the syrup, and the mixture was filtered to obtain 13g of solid residue and 280mL of filtrate. The filtrate was analyzed, as shown in Table 8.

[0093] Table 8

[0094] Liquid chromatography content External standard content Sucralose 1.99％ Sucralose 7.04％ Sucralose 1.26％ 2.22g / L Sucralose 4.82％ Sucralose-6-ethyl ester 65.06％ 121.63g / L

[0095] The mass of sucralose-6-ethyl ester in the filtrate is 121.63 × 0.280 = 34.06 g.

[0096] Yield = 34.06 ÷ 49 = 69.51%.

[0097] The experimental results of Example 5 and Comparative Examples 1-3 demonstrate that the present invention can achieve continuous operation of the high-temperature chlorination section in sucralose production while obtaining a high yield.

[0098] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Other variations and modifications may be made without departing from the technical solutions described in the claims.

[0099] In the description of this invention, it should be understood that the terms indicating orientation or positional relationship are based on the orientation or positional relationship shown in the drawings and are only for the convenience of describing the invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention.

Claims

1. A device for chlorinating sucralose with built-in continuous heating, characterized in that: The system includes a continuous heating tower and a condenser. The lower end of the continuous heating tower is a reboiler. A heater is built into the upper end of the reboiler. A condenser tube is built into the upper part of the continuous heating tower. A cavity section is formed between the heater and the condenser tube. The condenser tube has a shell-side inlet at the upper end and a shell-side outlet at the lower end. The shell-side inlet is connected to a feed pipeline. A feed port is located at the center of the cavity section. A liquid phase inlet is located above the feed port of the cavity section. The gas outlet at the top of the continuous heating tower is connected to the condenser inlet via a pipeline. The gas phase outlet of the condenser is connected to a tail gas treatment pipeline, and the liquid phase outlet is connected to the liquid phase inlet of the cavity section via a pipeline. The shell-side outlet is connected to the feed port via a pipeline. A steam jacket is provided outside the reboiler, and an outlet is provided at the bottom of the reboiler. The heater has a steam inlet and a steam-water outlet. The steam-water outlet is connected to the steam-water inlet of the steam jacket via a pipeline.

2. The device for chlorinating sucralose with built-in continuous heating according to claim 1, characterized in that: The bottom of the tower is also provided with a circulation outlet, and the cavity section is provided with a circulation inlet at the lower end of the feed inlet. The circulation outlet is connected to the circulation inlet through a pipeline, and at least one circulation pump, a second flow meter and a second thermometer are provided on the connecting pipeline of the circulation outlet.

3. The device for chlorinating sucralose with built-in continuous heating according to claim 1, characterized in that: The continuous heating tower is equipped with a first differential pressure level gauge at the top of the upper tube sheet of the heater and a second differential pressure level gauge at the height of the circulation inlet.

4. The device for chlorinating sucralose with built-in continuous heating according to claim 1, characterized in that: At least one feed pump is provided on the feed pipeline, and a first flow meter and a first thermometer are provided between the feed pump and the shell inlet.

5. The device for chlorinating sucralose with built-in continuous heating according to claim 1, characterized in that: A fifth thermometer is installed on the connecting pipeline between the shell outlet and the feed inlet, a fourth thermometer is installed on the connecting pipeline at the top outlet of the continuous heating tower, and a sixth thermometer is installed on the connecting pipeline at the liquid phase outlet of the condenser.

6. The device for chlorinating sucralose with built-in continuous heating according to claim 1, characterized in that: The bottom outlet of the tower is connected to the downstream device via a pipeline. The pipeline connecting the bottom outlet is equipped with a third flow meter, a third thermometer, and at least one extraction pump.

7. A heating method for the built-in continuous heating device for sucralose chlorination as described in claim 1, characterized in that, Includes the following steps: (1) The feed pump delivers the low-temperature chlorinated liquid from the low-temperature chlorination section to the inlet of the shell side of the condenser tube. The low-temperature chlorinated liquid enters the shell side of the condenser tube and is heated by the rising trichloroethane gas phase during the descent process in the shell side of the condenser tube. After the first heating is completed, it flows out from the outlet of the shell side of the condenser tube and enters the cavity section through the feed port. (2) The chlorinated liquid entering the cavity section falls into the tube side of the heater under the action of gravity, is heated by the steam in the tube side of the heater, and enters the tower bottom after completing the second heating. (3) The steam in the heater tube flows out through the steam water outlet and then enters the steam jacket of the tower through the steam water inlet of the tower bottom steam jacket to heat the tower bottom. The chlorination liquid entering the tower bottom completes the third heating in the tower bottom. (4) A portion of the high-temperature chlorination liquid in the tower is transported to the circulation inlet through the circulation pump and enters the cavity section. Under the action of gravity, it falls into the tube side of the heater to achieve circulation heating; another portion is extracted through the extraction outlet and transported to the downstream unit through the extraction pump. (5) After the chlorinated liquid is heated in the continuous heating tower, the trichloroethane vaporizes and rises into the cavity section, and then continues to rise into the shell side of the condenser tube. It is condensed and liquefied by the low temperature chlorinated liquid in the shell side of the condenser tube, and then falls back into the tower under the action of gravity. A small part of the uncondensed trichloroethane gas phase enters the condenser for condensation and liquefaction. After liquefaction, it is discharged from the liquid phase outlet and flows into the continuous heating tower through the liquid phase inlet. The uncondensed gas phase enters the tail gas treatment pipeline through the gas phase outlet.

8. The heating method of the built-in continuous heating device for sucralose chlorination according to claim 7, characterized in that: In step (1), the temperature of the low-temperature chlorine liquid delivered to the shell-side inlet of the condenser tube is 5°C. After the first heating is completed, the temperature of the chlorine liquid flowing out from the shell-side outlet of the condenser tube is 79-82°C. In step (4), the temperature of the high-temperature chlorine liquid delivered to the circulation inlet by the circulation pump is 116-119°C. In step (5), the temperature of the trichloroethane liquid phase discharged from the liquid phase outlet of the condenser is 45-51°C.

9. The heating method of the built-in continuous heating device for sucralose chlorination according to claim 7, characterized in that: The combined flow rate of the extraction pump, the condenser vapor outlet flow rate, and the feed pump flow rate are balanced.

10. The heating method of the built-in continuous heating device for sucralose chlorination according to claim 7, characterized in that: The liquid level of the material in the cavity section is near the midpoint between the upper tube sheet of the heater and the circulation inlet.

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