An energy-saving treatment device and method for sucralose ethyl acetate wastewater

Abstract

The present invention relates to the field of chemical engineering technology, and discloses an energy-saving wastewater treatment device and method for sucralose ethyl acetate, comprising the following steps: 1) self-heat exchange; 2) slag-gas separation; 3) rectification; 4) phase separation. The present invention does not produce wastewater with a high COD content, and separates the sucralose ethyl acetate wastewater into three parts: 1) separating relatively pure water (H2O content > 99.99%) for reuse in the production workshop; 2) separating the ethyl acetate phase (EA > 96.85%) for reuse in the production workshop; 3) separating the slag liquid for harmless treatment in an incinerator. And by setting a first compressor and a second compressor, as well as a self-heat exchanger group, the work done by the compressor is used to supply heat to the gas-phase material at the top of the rectification column and transfer heat to the sucralose ethyl acetate wastewater, so that the sucralose ethyl acetate wastewater is gradually heated and vaporized, greatly reducing the heat power consumption and refrigeration power consumption of the process. The proportion of the saved heating power and the saved refrigeration power is about 80%.

Description

Technical Field

[0001] The present invention relates to the field of chemical engineering technology, and particularly relates to an energy-saving treatment device and method for ethyl acetate wastewater in sucralose production. Background Art

[0002] During the production process of sucralose, a large amount of ethyl acetate wastewater is generated in the extraction process. Approximately 17 tons of ethyl acetate wastewater is produced for every 1 ton of sucralose produced. Since water and ethyl acetate are partially miscible, the chemical oxygen demand (COD) value of this ethyl acetate wastewater is as high as tens of thousands or even greater than 100,000 milligrams per liter (the discharge standard is 50 milligrams per liter). In addition, these ethyl acetate wastewaters contain relatively high amounts of salts (sodium chloride) and chlorinated sucralose impurities, and must be properly treated to prevent pollution of water bodies and the soil environment.

[0003] The detection data of sucralose ethyl acetate wastewater is shown in Table 1.

[0004] Table 1

[0005] Component Name Code Content Water <![CDATA[H2O]]> 65％ Sucralose Impurity GL 12％ Sodium Chloride NaCl 15％ Ethyl Acetate EA 8％ Total 100％

[0006] The difficulties in treating this wastewater are as follows:

[0007] 1) Ethyl acetate and water are azeotropes and the azeotropic composition is similar under different pressure conditions, so it is not suitable to use pressure swing distillation for separation.

[0008] 2) Sucralose ethyl acetate wastewater contains solid substances such as sodium chloride salt and chlorinated sucralose impurities, and the proportion of solid substances is as high as 27%. When the water content is reduced to a certain extent, these solid substances are likely to block pipelines and equipment.

[0009] 3) The amount of sucralose ethyl acetate wastewater is large, with a daily output of 300 tons. The heat consumption and refrigeration power consumption of conventional evaporation, condensation, and distillation operations are both very large, which also greatly increases the production cost of sucralose.

[0010] 4) Sucralose ethyl acetate wastewater contains about 8% ethyl acetate, and as much as possible needs to be recovered and reused. Among the 300 tons of wastewater generated every day, 24 tons of ethyl acetate are contained.

[0011] The patent with the application number 201810285758.2 discloses a process method and system for separating a mixture of ethanol, ethyl acetate, and water. The valuable feed liquid is sent to a pretreatment tower to separate the oil phase. The oil phase enters the ethyl acetate product tower and is heated by the reboiler of the ethyl acetate product tower that provides heat with primary steam. The steam rises to the top of the ethyl acetate product tower. After the steam at the top of the ethyl acetate product tower is cooled by heat exchange through the reboiler of the deweighting tower, a part of the condensed liquid is refluxed to the ethyl acetate product tower, and a part is withdrawn. This heat exchange method is called the countercurrent coupling distillation process.

[0012] Regarding the ethyl acetate product column as the stripping section and the heavy component removal column as the rectifying section, with internal heat integration within the rectifying and stripping sections, this rectification method is called internal heat-coupled rectification.

[0013] Problems existing in this method:

[0014] 1) The water content in the raw material is relatively low (16.65% - 39.18%), while the ethyl acetate content and ethanol content are relatively high. This raw material has high economic value. Therefore, the patent with the application number 201810285758.2 focuses on how to recover ethyl acetate and ethanol and does not consider the problem of wastewater treatment. In the wastewater of sucralose ethyl acetate in the present invention, the ethyl acetate content is low (8%), the water content is high (65%), and the useless chlorinated sucrose impurities (12%) and sodium chloride (15%) are relatively high. The focus is on the problem of wastewater treatment, especially the problem of high energy consumption in crystallization, and the problem of ethyl acetate recovery is also considered.

[0015] 2) In the ethyl acetate rectification column in the patent with the application number 201810285758.2, the pressure inside the column is adjusted to 0.2 - 0.5 MPa and the bottom temperature is 130°C - 140°C by controlling the regulating valve. This is different from the heat pump principle of compressor work. To reach the designed temperature and pressure values through the "pressure holding" method, a large amount of steam needs to be consumed by the reboiler, which is essentially different from the conversion of compressor work into the internal energy of the gas-phase material. Additionally, when the temperature exceeds 100°C and sodium chloride is present, a chemical reaction of ethyl acetate decomposition occurs, and the products are acetic acid and ethanol.

[0016] 3) The method of directly heating the bottom stream with the top gas-phase material saves very limited thermal power.

[0017] In summary, there is an urgent need to develop an energy-saving device and method for treating sucralose ethyl acetate wastewater, which does not produce wastewater with a high COD content, recovers the separated water and ethyl acetate for reuse, and simultaneously reduces thermal power consumption and refrigeration power consumption as much as possible. Summary of the Invention

[0018] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide an energy-saving device and method for treating sucralose ethyl acetate wastewater. This method can separate relatively pure water (H2O content > 99.99%), which can be re-introduced into the production of sucralose; separate the ethyl acetate phase (EA content > 96.85%), which can be re-introduced into the production of sucralose; separate the oil phase (a mixture containing water, sodium chloride salt, and chlorinated sucrose impurities), and send it to the incinerator for harmless treatment, without producing wastewater with a high COD, and simultaneously reducing thermal power consumption and refrigeration power consumption.

[0019] To achieve the above purpose, the technical solution of the present invention is: an energy-saving method for treating sucralose ethyl acetate wastewater, comprising the following steps:

[0020] (1) Self-heat exchange

[0021] After the sucralose ethyl acetate wastewater enters the wastewater storage tank, it is fed into the self-heat exchanger group by the first transfer pump. The self-heat exchanger group consists of five heat exchangers, namely the first heat exchanger, the second heat exchanger, the third heat exchanger, the fourth heat exchanger, and the fifth heat exchanger, which are vertically connected in series from bottom to top. The wastewater enters from the bottom tube-side inlet of the first heat exchanger and is taken out from the top tube-side outlet of the fifth heat exchanger. During this process, the sucralose ethyl acetate wastewater gradually absorbs the heat in the shell side of the self-heat exchanger group, heats up and vaporizes;

[0022] The gas phase coming out from the top of the rectification column enters the first compressor, and after pressurization, it enters the shell side of the fourth heat exchanger. After heat exchange, it enters the first flash evaporator from the outlet of the shell side of the fourth heat exchanger. The gas phase enters the second compressor from the top outlet of the first flash evaporator, and after pressurization, it successively enters the shell sides of the fifth heat exchanger, the third heat exchanger, the second heat exchanger, and the first heat exchanger. After heat exchange, it is taken out from the outlet of the shell side of the first heat exchanger and merged with the liquid phase at the bottom of the first flash evaporator to enter the tube side of the eighth heat exchanger for cooling;

[0023] (2) Slag-gas separation

[0024] The liquid material taken out from the top tube-side outlet of the fifth heat exchanger enters the tube side of the sixth heat exchanger for further gasification, and then enters the second flash evaporator from the outlet of the tube side of the sixth heat exchanger. The gas phase at the top of the second flash evaporator enters the rectification column, and the slag liquid at the bottom is transported to the incinerator for harmless treatment by the second transfer pump;

[0025] (3) Rectification

[0026] The aqueous phase taken out from the bottom of the rectification column is transported to the production workshop for reuse by the third transfer pump;

[0027] The liquid material from the outlet of the eighth heat exchanger enters the diverter and is divided into two streams. One stream returns to the top of the rectification column, and the other stream enters the phase separator;

[0028] (4) Phase separation

[0029] The liquid material is stratified in the phase separator. The lower aqueous phase is taken out and enters the aqueous phase tank, and then is transported to the inlet of the tube side of the first heat exchanger by the fourth transfer pump; the upper ester phase of the phase separator is taken out and enters the ester phase tank, and then is transported to the production workshop for reuse by the fifth transfer pump.

[0030] The present invention does not produce wastewater with a high COD content, and separates the sucralose ethyl acetate wastewater into three parts:

[0031] 1) Separate relatively pure water (H2O content > 99.99%) for reuse in the production workshop;

[0032] 2) Separate the ethyl acetate phase (EA > 96.85%) and send it to the production workshop for reuse;

[0033] 3) Separate the residue liquid and send it to the incinerator for harmless treatment.

[0034] Moreover, by setting the first compressor, the second compressor, and the self-heat exchanger group, the sucralose ethyl acetate wastewater gradually absorbs the heat in the shell side of the self-heat exchanger group, heats up and vaporizes, greatly reducing the heat power consumption and refrigeration power consumption of the process.

[0035] Furthermore; the components and mass percentages of the sucralose ethyl acetate wastewater in step (1) are as follows: water 65%, chlorinated sucralose impurities 12%, sodium chloride 15%, and ethyl acetate 8%.

[0036] Furthermore; the outlet pressure of the first compressor in step (1) is 10 - 30 kPa, and the temperature is 71.29 - 94.07 °C; the outlet pressure of the second compressor is 16 - 48 kPa, and the temperature is 73.00 - 94.75 °C.

[0037] Furthermore; the ratio of the flow rate of the residue liquid discharged from the bottom of the second flash evaporator in step (2) to the feed flow rate of the sucralose ethyl acetate wastewater in step (1) is 37.85%, and the water content of the residue liquid is 28.54%.

[0038] Furthermore; the top pressure of the distillation column in step (3) is 5 - 15 kPa, and the temperature is 28.78 - 49.32 °C; the bottom pressure of the distillation column is 10 - 20 kPa, and the temperature is 45.80 - 60.06 °C.

[0039] Furthermore; the ratio of the flow rate of the reflux controlled by the diverter in step (3) to the flow rate of the ester phase withdrawn by the phase separator in step (4) is 12.24 - 12.31.

[0040] Furthermore; the water content in the aqueous phase withdrawn from the bottom of the distillation column in step (3) > 99.99%.

[0041] Furthermore; the ethyl acetate content in the ester phase of the ester phase tank in step (4) > 96.85%.

[0042] Another technical solution of the present invention is: an energy-saving sucralose ethyl acetate wastewater treatment device, including a wastewater storage tank, a self-heat exchanger group, a sixth heat exchanger, a seventh heat exchanger, an eighth heat exchanger, a distillation column, a first compressor, a second compressor, a phase separator, an aqueous phase tank, an ester phase tank, a first transfer pump, a second transfer pump, a third transfer pump, a fourth transfer pump, a fifth transfer pump, and a diverter; the self-heat exchanger group is vertically connected in series from bottom to top by five heat exchangers, namely the first heat exchanger, the second heat exchanger, the third heat exchanger, the fourth heat exchanger, and the fifth heat exchanger;

[0043] The ethyl acetate wastewater pipeline of sucralose is connected to the inlet of the wastewater temporary storage tank. The outlet of the wastewater temporary storage tank is connected to the inlet of the first transfer pump. After the outlet pipelines of the first transfer pump and the fourth transfer pump are merged, they are connected to the inlet of the bottom tube side of the first heat exchanger. The outlet of the top tube side of the first heat exchanger is connected to the inlet of the bottom tube side of the second heat exchanger. The outlet of the top tube side of the second heat exchanger is connected to the inlet of the bottom tube side of the third heat exchanger. The outlet of the top tube side of the third heat exchanger is connected to the inlet of the bottom tube side of the fourth heat exchanger. The outlet of the top tube side of the fourth heat exchanger is connected to the inlet of the bottom tube side of the fifth heat exchanger. The outlet of the top tube side of the fifth heat exchanger is connected to the inlet of the top tube side of the sixth heat exchanger. The outlet of the bottom tube side of the sixth heat exchanger is connected to the inlet of the second flash evaporator. The top outlet of the second flash evaporator is connected to the gas phase inlet of the rectifying column. The bottom outlet of the second flash evaporator is connected to the inlet of the second transfer pump. The outlet pipeline of the second transfer pump is connected to the incinerator device;

[0044] The gas phase outlet at the top of the rectifying column is connected to the inlet of the first compressor. The aqueous phase outlet at the bottom of the rectifying column is connected to the inlet of the third transfer pump. The outlet pipeline of the third transfer pump is connected to the pure water reuse device in the sucralose workshop. The outlet of the first compressor is connected to the inlet of the upper shell side of the fourth heat exchanger. The outlet of the lower shell side of the fourth heat exchanger is connected to the inlet of the first flash evaporator. The top outlet of the first flash evaporator is connected to the inlet of the second compressor. The outlet of the second compressor is connected to the inlet of the upper shell side of the fifth heat exchanger. The outlet of the lower shell side of the fifth heat exchanger is connected to the inlet of the upper shell side of the third heat exchanger. The outlet of the lower shell side of the third heat exchanger is connected to the inlet of the upper shell side of the second heat exchanger. The outlet of the lower shell side of the second heat exchanger is connected to the inlet of the upper shell side of the first heat exchanger. After the outlet pipeline of the lower shell side of the first heat exchanger and the outlet pipeline at the bottom of the first flash evaporator are merged, they are connected to the inlet of the bottom tube side of the eighth heat exchanger. The outlet of the top tube side of the eighth heat exchanger is connected to the inlet of the diverter. The pipeline of the reflux port of the diverter is connected to the upper reflux inlet of the rectifying column. The pipeline of the extraction outlet of the diverter is connected to the top inlet of the phase separator. The aqueous phase outlet of the phase separator is connected to the top inlet of the aqueous phase tank. The bottom outlet of the aqueous phase tank is connected to the inlet of the fourth transfer pump. The ester phase outlet of the phase separator is connected to the top inlet of the ester phase tank. The bottom outlet of the ester phase tank is connected to the inlet of the fifth transfer pump. The outlet pipeline of the fifth transfer pump is connected to the ethyl acetate reuse device in the sucralose workshop.

[0045] The device of the present invention can separate the ethyl acetate wastewater of sucralose, and finally obtain relatively pure water (H2O content > 99.99%), ethyl acetate phase (EA content > 96.85%), and the residue liquid with a water content of 28.54% is sent to the incinerator for harmless treatment. Brief Description of the Drawings

[0046] Figure 1 It is a schematic structural diagram of the device of the present invention.

[0047] In the figure: 1. First heat exchanger; 2. Second heat exchanger; 3. Third heat exchanger; 4. Fourth heat exchanger; 5. Fifth heat exchanger; 6. Sixth heat exchanger; 7. Seventh heat exchanger; 8. Eighth heat exchanger; 9. Wastewater temporary storage tank; 10. First compressor; 11. Second compressor; 12. First flash evaporator; 13. Second flash evaporator; 14. Distillation column; 15. Phase separator; 16. Aqueous phase tank; 17. Ester phase tank; 18. First transfer pump; 19. Second transfer pump; 20. Third transfer pump; 21. Fourth transfer pump; 22. Fifth transfer pump; 23. Shunt; 24. Self-heat exchanger group. Detailed implementation mode

[0048] Example 1:

[0049] As Figure 1 shown, an energy-saving sucralose ethyl acetate wastewater treatment device includes a wastewater temporary storage tank 9, a self-heat exchanger group 24, a sixth heat exchanger 6, a seventh heat exchanger 7, an eighth heat exchanger 8, a distillation column 14, a first compressor 10, a second compressor 11, a phase separator 15, an aqueous phase tank 16, an ester phase tank 17, a first transfer pump 18, a second transfer pump 19, a third transfer pump 20, a fourth transfer pump 21, a fifth transfer pump 22 and a shunt 23; the self-heat exchanger group 24 is vertically and serially composed of five heat exchangers, namely a first heat exchanger 1, a second heat exchanger 2, a third heat exchanger 3, a fourth heat exchanger 4 and a fifth heat exchanger 5 from bottom to top;

[0050] The sucralose ethyl acetate wastewater enters the wastewater temporary storage tank 9. The bottom outlet of the wastewater temporary storage tank 9 is connected to the inlet of the first transfer pump 18. A thermometer, a pressure gauge and a flow meter are arranged on the pipeline FEED at the outlet of the first transfer pump 18. The pipeline FEED and the outlet pipeline of the fourth transfer pump 21 are merged into a pipeline E1IN and then connected to the bottom tube side inlet of the first heat exchanger 1;

[0051] The top tube side outlet of the first heat exchanger 1 is connected to the bottom tube side inlet of the second heat exchanger 2. The top tube side outlet of the second heat exchanger 2 is connected to the bottom tube side inlet of the third heat exchanger 3. The top tube side outlet of the third heat exchanger 3 is connected to the bottom tube side inlet of the fourth heat exchanger 4. The top tube side outlet of the fourth heat exchanger 4 is connected to the bottom tube side inlet of the fifth heat exchanger 5. The pipeline E6IN at the top tube side outlet of the fifth heat exchanger 5 is connected to the top tube side inlet of the sixth heat exchanger 6. The bottom tube side outlet of the sixth heat exchanger 6 is connected to the inlet of the second flash evaporator 13. The top outlet pipeline T1IN of the second flash evaporator 13 is connected to the gas phase inlet of the distillation column 14. The bottom outlet pipeline RESIDUE of the second flash evaporator 13 is connected to the inlet of the second transfer pump 19; the outlet of the second transfer pump 19 is connected to an incinerator device.

[0052] The gas-phase outlet pipeline C1IN at the top of the rectifying column 14 is connected to the inlet of the first compressor 10. The outlet pipeline C1OUT of the first compressor 10 is connected to the inlet of the upper shell side of the fourth heat exchanger 4. The outlet of the lower shell side of the fourth heat exchanger 4 is connected to the inlet of the first flash separator 12. The top outlet pipeline C2IN of the first flash separator 12 is connected to the inlet of the second compressor 11. The outlet pipeline C2OUT of the second compressor 11 is connected to the inlet of the upper shell side of the fifth heat exchanger 5. The outlet of the lower shell side of the fifth heat exchanger 5 is connected to the inlet of the upper shell side of the third heat exchanger 3. The outlet of the lower shell side of the third heat exchanger 3 is connected to the inlet of the upper shell side of the second heat exchanger 2. The outlet of the lower shell side of the second heat exchanger 2 is connected to the inlet of the upper shell side of the first heat exchanger 1. The outlet pipeline of the lower shell side of the first heat exchanger 1 and the bottom outlet pipeline of the first flash separator 12 are merged into pipeline E8IN and then connected to the bottom tube side inlet of the eighth heat exchanger 8. The top tube side outlet of the eighth heat exchanger 8 is connected to the inlet of the diverter 23. The reflux pipeline RE of the diverter is connected to the upper reflux inlet of the rectifying column 14. The extraction outlet pipeline V4IN of the diverter 23 is connected to the top inlet of the phase separator 15. The aqueous phase outlet pipeline V4-2 of the phase separator 15 is connected to the top inlet of the aqueous phase tank 16. The bottom outlet of the aqueous phase tank 16 is connected to the inlet of the fourth delivery pump 21. The ester phase outlet pipeline V4-1 of the phase separator 15 is connected to the top inlet of the ester phase tank 17. The bottom outlet of the ester phase tank 17 is connected to the inlet of the fifth delivery pump 22. The outlet pipeline of the fifth delivery pump 22 is connected to the ethyl acetate reuse device in the sucralose workshop.

[0053] A seventh heat exchanger 7 is provided at the bottom of the rectifying column 14. The bottom outlet pipeline WATER of the rectifying column 14 is connected to the third delivery pump 20. The outlet pipeline of the third delivery pump 20 is connected to the pure water reuse device in the sucralose workshop.

[0054] Preferably in this embodiment, the diverter 23 is composed of a tee, regulating valves and flow meters on two branches of the tee.

[0055] An energy-saving method for treating sucralose ethyl acetate wastewater includes the following steps:

[0056] (1) Self-heat exchange

[0057] After the sucralose ethyl acetate wastewater stream (flow rate 12500 kg / h) enters the wastewater storage tank 9, it is transported by the first delivery pump 18 to pipeline FEED, merged with the stream extracted by the fourth delivery pump 21 and then enters pipeline E1IN, and then successively enters the tube side of the first heat exchanger 1, the tube side of the second heat exchanger 2, the tube side of the third heat exchanger 3, the tube side of the fourth heat exchanger 4 and the tube side of the fifth heat exchanger 5. The sucralose ethyl acetate wastewater gradually absorbs the heat in the shell side of the heat exchanger and is heated and vaporized in this process.

[0058] The gas phase emerging from the top of the rectification column 14 enters the first compressor 10 through pipeline C1IN, is pressurized and then enters pipeline C1OUT, and then enters the shell side of the fourth heat exchanger 4 (transferring heat to the liquid in the tube side of the fourth heat exchanger 4). After heat exchange, it enters the first flash evaporator 12 from the outlet of the shell side of the fourth heat exchanger 4. The gas phase enters the second compressor 11 along pipeline C2IN from the top of the first flash evaporator 12, is pressurized and then enters the shell side of the fifth heat exchanger 5 along pipeline C2OUT (transferring heat to the liquid in the tube side of the fifth heat exchanger 5). After heat exchange, it enters the shell side of the third heat exchanger 3 from the outlet of the shell side of the fifth heat exchanger 5 (transferring heat to the liquid in the tube side of the third heat exchanger 3). After heat exchange, it enters the shell side of the second heat exchanger 2 from the outlet of the shell side of the third heat exchanger 3 (transferring heat to the liquid in the tube side of the second heat exchanger 2). After heat exchange, it enters the shell side of the first heat exchanger 1 from the outlet of the shell side of the second heat exchanger 2 (transferring heat to the liquid in the tube side of the first heat exchanger 1). After heat exchange, it is taken out from the outlet of the shell side of the first heat exchanger 1 and merged with the liquid phase at the bottom of the first flash evaporator 12 to enter the tube side of the eighth heat exchanger 8 through pipeline E8IN for cooling.

[0059] (2) Slag gas separation

[0060] The liquid in the tube side of the fifth heat exchanger 5 enters the tube side of the sixth heat exchanger 6 through pipeline E6IN and is further vaporized, and then enters the second flash evaporator 13 from the outlet of the tube side of the sixth heat exchanger 6. The gas phase at the top of the second flash evaporator 13 enters the rectification column 14, and the slag liquid at the bottom of the second flash evaporator 13 enters the second transfer pump 19 through pipeline RESIDUE and is transported by the second transfer pump 19 to the incinerator for harmless treatment.

[0061] (3) Rectification

[0062] The water taken out from the bottom of the rectification column 14 enters the third transfer pump 20 along pipeline WATER and is transported to the production workshop for reuse by controlling a certain flow rate.

[0063] The liquid from the outlet of the eighth heat exchanger 8 enters the diverter 23 and is divided into two streams. One stream returns to the top of the rectification column 14 through pipeline RE, and the other stream enters the phase separator 15 through pipeline V4IN.

[0064] (4) Phase separation

[0065] The liquid in the phase separator 15 is partially stratified. The lower aqueous phase is separated from the low-level baffle and enters the aqueous phase tank 16 along pipeline V4-2, and then is transported to the inlet of the tube side of the first heat exchanger 1 by the fourth transfer pump 21; the upper ester phase of the phase separator 15 is separated from the high-level baffle and enters the ester phase tank 17 along pipeline V4-1, and then is transported to the production workshop for reuse by the fifth transfer pump 22.

[0066] Record the temperature, pressure and power parameters of the distillation column 14, the first compressor 10 and the second compressor 11 respectively, see Table 2; record the temperature, pressure, flow rate and composition data of the internal streams in the pipelines FEED, C1IN, C1OUT, C2IN, C2OUT, RE, RESIDUE, V4-1, WATER respectively, see Table 3, and count the power of each compressor and heat exchanger, see Table 4.

[0067] Table 2

[0068] Measurement Location Temperature Unit Pressure Unit Top of Rectifying Column 14 41.37 ℃ 10 kPa Bottom of Rectifying Column 14 53.97 ℃ 15 kPa Outlet of First Compressor 10 85.27 ℃ 20 kPa Outlet of Second Compressor 11 87.34 ℃ 32 kPa

[0069] Table 3

[0070] Unit FEED C1IN C1OUT C2IN C2OUT RE RESIDUE V4-1 WATER Phase Liquid Phase Vapor Phase Vapor Phase Vapor Phase Vapor Phase Liquid Phase Liquid Phase Liquid Phase Liquid Phase Temperature ℃ 20 41.37 85.27 57.02 87.34 18.55 61.83 16.89 53.97 Pressure kPa 400 10 20 20 32 15 15 15 15 Mass Density <![CDATA[kg / m 3 > 752.34 0.12 0.22 0.24 0.35 960.43 519.81 960.43 965.56 Mass Flow Rate kg / h 12500 14447.71 14447.71 14447.71 14447.71 12547.71 4732.38 1022.34 6745.22 <![CDATA[Water H2O]]> kg / h 8125 6360.97 6360.97 6360.97 6360.97 5524.47 1350.56 29.47 6744.93 Sucralose Impurity GL kg / h 1500 0 0 0 0 0 1499.7 0 0.3 Sodium Chloride NaCl kg / h 1875 0 0 0 0 0 1875 0 0 Ethyl Acetate EA kg / h 1000 8086.74 8086.74 8086.74 8086.74 7023.24 7.12 992.88 0 Mass Fraction <![CDATA[Water H2O]]> 65.00％ 44.03％ 44.03％ 44.03％ 44.03％ 44.03％ 28.54％ 2.88％ 99.9956％ Sucralose Impurity GL 12.00％ 0 0 0 0 0 31.69％ 0 0.0044％ Sodium Chloride NaCl 15.00％ 0 0 0 0 0 39.62％ 0 0 Ethyl Acetate EA 8.00％ 55.97％ 55.97％ 55.97％ 55.97％ 55.97％ 0.15％ 97.12％ 0 Volume Flow Rate <![CDATA[m 3 / h]]> 16.61 116163.48 66147.96 60903.14 41531.16 13.06 9.1 1.12 6.99

[0071] As can be seen from Table 3, the flow rate of the pipeline WATER is 6745.22 kg / h, the content w(H2O)=99.9956%, the water recovery rate is 6744.93÷8125 = 83.01%, and the remaining un-recovered water (proportion 16.99%) together with 1499.70 kg / h of sucralose chloride impurities and 1875 kg / h of sodium chloride enter the incinerator for harmless treatment, completely eliminating the generation of high-COD wastewater.

[0072] In addition, the ethyl acetate in the pipeline V4-1 enters the sucralose workshop for reuse, the recovery rate of ethyl acetate is 992.88÷1000 = 99.288%, and the proportion of un-recovered ethyl acetate 0.712% enters the slag liquid RESIDUE and goes to the incinerator for harmless treatment.

[0073] Table 4

[0074]

[0075] Comparative Example 1

[0076] An energy-saving sucralose ethyl acetate wastewater treatment device and method are the same as those in Example 1, the difference is that the self-heat exchanger group 24 (the first heat exchanger 1, the second heat exchanger 2, the third heat exchanger 3, the fourth heat exchanger 4, the fifth heat exchanger 5) is cancelled, and at the same time the first compressor 10 and the second compressor 11 are cancelled, the operating parameters of the distillation column 14 remain unchanged, and the gas-phase stream at the top of the distillation column 14 directly enters the tube-side inlet of the eighth heat exchanger 8 along the pipeline E8IN.

[0077] Statistically summarize the temperature, pressure and composition data of the pipelines FEED, E8IN, RE, RESIDUE, V4-1, WATER into Table 5, and statistically summarize the power parameters of each heat exchanger into Table 6.

[0078] Table 5

[0079]

[0080]

[0081] Table 6

[0082]

[0083]

[0084] By comparing Table 4 and Table 6, it can be seen that by setting the self-heat exchanger group 24, the first compressor 10, and the second compressor 11, the present invention only increases the electric power by 529.583 kW, but can save the thermal power by 5790.311 - 994.085 = 4796.226 kW, and the heat saving rate is 4796.226÷5790.311 = 82.83%; at the same time, the present invention saves the refrigeration power by 5404.48 - 1086.24 = 4318.24 kW, and the refrigeration saving rate is 4318.24÷5404.48 = 79.90%. The above data shows that the energy-saving effect of the present invention is very significant.

[0085] Example 2

[0086] An energy-saving sucrose acetate isopropyl ester wastewater treatment device and method are the same as those in Example 1, except that the pressure of the rectification column 14 is changed (the top of the column is 5 kPa and the bottom of the column is 10 kPa), and the temperature, pressure, and power parameters of the rectification column 14, the first compressor 10, and the second compressor 11 are respectively recorded, as shown in Table 7; the temperature, pressure, flow rate, and composition data of the internal streams in the pipelines FEED, C1IN, C1OUT, C2IN, C2OUT, RE, RESIDUE, V4-1, and WATER are respectively recorded, as shown in Table 8.

[0087] Table 7

[0088] Measurement Location Temperature Unit Pressure Unit Top of Rectifying Column 14 28.78 ℃ 5 kPa Bottom of Rectifying Column 14 45.80 ℃ 10 kPa Outlet of First Compressor 10 71.29 ℃ 10 kPa Outlet of Second Compressor 11 73.00 ℃ 16 kPa

[0089] Table 8

[0090]

[0091]

[0092] Example 3

[0093] An energy-saving wastewater treatment device and method for ethyl acetate of sucralose, which is the same as Example 1, except that the pressure of the rectification column is changed (15 kPa at the top of the column and 20 kPa at the bottom of the column), and the temperature, pressure and power parameters of the rectification column 14, the first compressor 10 and the second compressor 11 are recorded respectively, as shown in Table 9; the temperature, pressure, flow rate and composition data of the internal streams in the pipelines FEED, C1IN, C1OUT, C2IN, C2OUT, RE, RESIDUE, V4-1 and WATER are recorded respectively, as shown in Table 10.

[0094] Table 9

[0095]

[0096] Table 10

[0097]

[0098]

[0099] The above-described embodiments are only preferred solutions of the present invention, and do not impose any form of limitation on the present invention. There are other variations and modifications without exceeding the technical solutions recorded in the claims.

[0100] In the description of the present invention, it should be understood that the terms indicating the 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 present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

Claims

1. An energy-saving method for treating wastewater from ethyl acetate of sucralose, characterized in that, It includes the following steps: (1) Self-heat exchange After the sucralose ethyl acetate wastewater enters the wastewater storage tank, it is fed into the self-heat exchanger group by the first transfer pump. The self-heat exchanger group consists of five heat exchangers, namely the first heat exchanger, the second heat exchanger, the third heat exchanger, the fourth heat exchanger, and the fifth heat exchanger, which are vertically connected in series from bottom to top. The wastewater enters from the bottom tube-side inlet of the first heat exchanger and is taken out from the top tube-side outlet of the fifth heat exchanger. The wastewater gradually absorbs the heat in the shell-side of the self-heat exchanger group and is heated and vaporized. The gas phase coming out from the top of the rectification column enters the first compressor, and after being pressurized, it enters the shell-side of the fourth heat exchanger. After heat exchange, it exits from the shell-side outlet of the fourth heat exchanger and enters the first flash separator. The gas phase exits from the top outlet of the first flash separator and enters the second compressor. After being pressurized, it sequentially enters the shell-side of the fifth heat exchanger, the shell-side of the third heat exchanger, the shell-side of the second heat exchanger, and the shell-side of the first heat exchanger. After heat exchange, it is taken out from the shell-side outlet of the first heat exchanger and is combined with the liquid phase at the bottom of the first flash separator and enters the tube-side of the eighth heat exchanger for cooling. (2) Slag-gas separation The liquid material taken out from the top tube-side outlet of the fifth heat exchanger enters the tube-side of the sixth heat exchanger for further vaporization, and then exits from the tube-side outlet of the sixth heat exchanger and enters the second flash separator. The gas phase at the top of the second flash separator enters the rectification column, and the bottom slag liquid is transported to the incinerator for harmless treatment by the second transfer pump. (3) Rectification The aqueous phase taken out from the bottom of the rectification column is transported to the production workshop for reuse by the third transfer pump. The liquid material from the outlet of the eighth heat exchanger enters the diverter and is divided into two streams. One stream returns to the top of the rectification column, and the other stream enters the phase separator. (4) Phase separation The liquid material is stratified in the phase separator. The lower aqueous phase is taken out and enters the aqueous phase tank, and then is transported to the inlet of the tube-side of the first heat exchanger by the fourth transfer pump. The upper ester phase in the phase separator is taken out and enters the ester phase tank, and then is transported to the production workshop for reuse by the fifth transfer pump.

2. The energy-saving method for treating sucralose ethyl acetate wastewater according to claim 1, wherein: The composition and mass percentage of the sucralose ethyl acetate wastewater in step (1) are as follows: water 65%, chlorinated sucralose impurities 12%, sodium chloride 15%, and ethyl acetate 8%.

3. The energy-saving method for treating sucralose ethyl acetate wastewater according to claim 1, wherein: In step (1), the outlet pressure of the first compressor is 10 - 30 kPa, and the temperature is 71.29 - 94.07 °C; the outlet pressure of the second compressor is 16 - 48 kPa, and the temperature is 73.00 - 94.75 °C.

4. The energy-saving method for treating sucralose ethyl acetate wastewater according to claim 1, wherein: In step (2), the ratio of the flow rate of the slag liquid discharged from the bottom of the second flash separator to the feed flow rate of the sucralose ethyl acetate wastewater in step (1) is 37.85%, and the mass percentage content of water in the slag liquid is 28.54%.

5. The energy-saving method for treating sucralose ethyl acetate wastewater according to claim 1, wherein: In step (3), the top pressure of the rectification column is 5 - 15 kPa, and the temperature is 28.78 - 49.32 °C; the bottom pressure of the rectification column is 10 - 20 kPa, and the temperature is 45.80 - 60.06 °C.

6. The energy-saving method for treating sucralose ethyl acetate wastewater according to claim 1, characterized in that: In step (3), the ratio of the flow rate of the reflux controlled by the diverter to the flow rate of the ester phase taken out from the phase separator in step (4) is 12.24 - 12.

31.

7. The energy-saving method for treating sucralose ethyl acetate wastewater according to claim 1, characterized in that: In step (3), the mass percentage content of water in the aqueous phase taken out from the bottom of the rectification column > 99.99%.

8. The energy-saving method for treating sucralose ethyl acetate wastewater according to claim 1, wherein: In step (4), the mass percentage content of ethyl acetate in the ester phase in the ester phase tank > 96.85%.

9. An energy-saving wastewater treatment device for sucralose ethyl acetate, characterized in that, It includes a wastewater temporary storage tank, a self-heat exchanger group, a sixth heat exchanger, a seventh heat exchanger, an eighth heat exchanger, a distillation column, a first compressor, a second compressor, a phase separator, an aqueous phase tank, an ester phase tank, a first transfer pump, a second transfer pump, a third transfer pump, a fourth transfer pump, a fifth transfer pump and a diverter; the self-heat exchanger group consists of five heat exchangers, namely a first heat exchanger, a second heat exchanger, a third heat exchanger, a fourth heat exchanger and a fifth heat exchanger, which are vertically connected in series from bottom to top. The sucralose ethyl acetate wastewater pipeline is connected to the inlet of the wastewater temporary storage tank, the outlet of the wastewater temporary storage tank is connected to the inlet of the first transfer pump, the outlet pipeline of the first transfer pump is merged with the outlet pipeline of the fourth transfer pump and then connected to the inlet of the bottom tube side of the first heat exchanger, the outlet of the top tube side of the first heat exchanger is connected to the inlet of the bottom tube side of the second heat exchanger, the outlet of the top tube side of the second heat exchanger is connected to the inlet of the bottom tube side of the third heat exchanger, the outlet of the top tube side of the third heat exchanger is connected to the inlet of the bottom tube side of the fourth heat exchanger, the outlet of the top tube side of the fourth heat exchanger is connected to the inlet of the bottom tube side of the fifth heat exchanger, the outlet of the top tube side of the fifth heat exchanger is connected to the inlet of the top tube side of the sixth heat exchanger, the outlet of the bottom tube side of the sixth heat exchanger is connected to the inlet of the second flash evaporator, the top outlet of the second flash evaporator is connected to the gas phase inlet of the distillation column, the bottom outlet of the second flash evaporator is connected to the inlet of the second transfer pump, and the outlet pipeline of the second transfer pump is connected to the incinerator device. The gas phase outlet at the top of the distillation column is connected to the inlet of the first compressor, the aqueous phase outlet at the bottom of the distillation column is connected to the inlet of the third transfer pump, the outlet pipeline of the third transfer pump is connected to the pure water reuse device in the sucralose workshop, the outlet of the first compressor is connected to the inlet of the upper shell side of the fourth heat exchanger, the outlet of the lower shell side of the fourth heat exchanger is connected to the inlet of the first flash evaporator, the top outlet of the first flash evaporator is connected to the inlet of the second compressor, the outlet of the second compressor is connected to the inlet of the upper shell side of the fifth heat exchanger, the outlet of the lower shell side of the fifth heat exchanger is connected to the inlet of the upper shell side of the third heat exchanger, the outlet of the lower shell side of the third heat exchanger is connected to the inlet of the upper shell side of the second heat exchanger, the outlet of the lower shell side of the second heat exchanger is connected to the inlet of the upper shell side of the first heat exchanger, the outlet pipeline of the lower shell side of the first heat exchanger is merged with the outlet pipeline of the bottom of the first flash evaporator and then connected to the inlet of the bottom tube side of the eighth heat exchanger, the outlet of the top tube side of the eighth heat exchanger is connected to the inlet of the diverter, the reflux port pipeline of the diverter is connected to the upper reflux inlet of the distillation column, the product outlet pipeline of the diverter is connected to the top inlet of the phase separator, the aqueous phase outlet of the phase separator is connected to the top inlet of the aqueous phase tank, the bottom outlet of the aqueous phase tank is connected to the inlet of the fourth transfer pump, the ester phase outlet of the phase separator is connected to the top inlet of the ester phase tank, the bottom outlet of the ester phase tank is connected to the inlet of the fifth transfer pump, and the outlet pipeline of the fifth transfer pump is connected to the ethyl acetate reuse device in the sucralose workshop.

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