Psicose rapid concentration system and method

Abstract

The invention provides a psicose rapid concentration system and method, and the method comprises the following steps: taking a psicose chromatography extracting solution, and carrying out evaporation treatment in a two-stage short-path distiller to obtain a psicose concentrated solution. The traditional process that materials enter a multi-effect tubular evaporator to be evaporated and concentrated is abandoned, a low-temperature ultralow vacuum mode of molecular distillation is innovated for rapid concentration, the situation that psicose is decomposed in the evaporator due to high temperature can be avoided through the system and the method, the color value of the materials can be effectively prevented from being increased, and the quality of psicose is improved. And the subsequent crystallization effect and the crystallization recovery rate are improved. The color value of the mother liquor after crystallization is also greatly reduced, and the industrial production cost caused by material decoloration due to pigment accumulation when the mother liquor is used mechanically is reduced.

Description

Technical Field

[0001] The present invention relates to the field of biomedical foods, and particularly to a rapid concentration system and method for allulose. Background Art

[0002] The tubular evaporator is a type of natural circulation evaporator. The heating steam enters the tube space, and the solution to be heated circulates along the tubes of the heating chamber. The tubular evaporator mainly includes a central circulation tube evaporator, a spiral tube evaporator, a coil tube evaporator, etc. Its working principle consists of two parts: a heating chamber and a separation chamber. The heating chamber, also known as the boiling chamber, is the part where the material is boiled by indirect heating with saturated steam. The separation chamber, also known as the evaporation chamber, after the solution is heated and boiled and vaporized in the heating chamber, a large amount of liquid droplets are carried in the secondary steam generated. By using the suddenly increased evaporation space in the evaporation chamber, the liquid droplets are condensed and settled to be separated from the steam.

[0003] At present, one production process of allulose is enzymatic production. The allulose extract obtained after chromatographic separation is then concentrated and crystallized to obtain the finished product through a concentration and crystallization process. The evaporation and concentration of the allulose extract mainly use a tubular evaporator for evaporation and concentration. Since the Brix of the allulose extract after chromatographic separation is relatively low, only 15% - 20%, some enterprises first use a membrane concentration technology to pre - concentrate the Brix of the extract to 35%, and then the pre - concentrated material enters a triple - effect or quadruple - effect tubular evaporator for concentration. Allulose is a heat - sensitive sugar. Generally, when the temperature exceeds 60°C during the evaporation and concentration process, allulose will decompose and change color. At the same time, due to the need for triple - effect or quadruple - effect evaporation, the evaporation time is long, and the temperature in each effect of the evaporation chamber is different. As the temperature changes increase, the color value of the material in the evaporation chamber also increases. Even when the evaporation temperature in the first effect is relatively high, some allulose has decomposed, and the decomposition rate can reach 2% - 4%, resulting in a decrease in the purity of the evaporated and concentrated product. The existing concentration and evaporation technology discharges the material when the allulose concentration in the evaporation chamber is concentrated to BX of 75% - 85%. After discharging, the color value of the concentrated liquid increases from 5 - 10 IU to 50 - 100 IU, and the purity of allulose detected by liquid phase decreases from more than 98% to 95% - 97%. Summary of the Invention

[0004] The technical problem to be solved by the present invention is the problem that allulose in the prior art is easily decomposed due to high temperature during evaporation and concentration, and the color value increases due to the long residence time in the tubular evaporator. The present invention provides a new rapid concentration system and method for allulose.

[0005] To solve the above - mentioned technical problems, the technical solution of the present invention is as follows: A rapid allulose concentration system, comprising a raw material tank, a first-stage short-path distiller, a pre-concentration buffer tank, a second-stage short-path distiller and a discharge buffer tank. The allulose chromatographic extract enters the first-stage short-path distiller from the raw material tank for first-stage distillation. The pre-concentrated allulose solution obtained enters the pre-concentration buffer tank and then enters the second-stage short-path distiller for second-stage distillation to obtain an allulose concentrate, which enters the discharge buffer tank.

[0006] Heat-conducting oil pipes are provided on the raw material tank, the first-stage short-path distiller and the second-stage short-path distiller as heating sources.

[0007] Vacuum pumping devices are provided on the first-stage short-path distiller and the second-stage short-path distiller. The vacuum pumping devices include a liquid nitrogen trap and a vacuum pump. The liquid nitrogen trap is connected to the distillation chamber of the short-path distiller through a pipeline, and the vacuum pump is connected to the liquid nitrogen trap through a pipeline. The liquid nitrogen trap, i.e., the liquid nitrogen cold trap, can be used to assist the vacuum pump to quickly reach an extremely low negative pressure.

[0008] Frequency conversion pumps are provided on the pipeline between the raw material tank and the first-stage short-path distiller and on the pipeline between the pre-concentration buffer tank and the second-stage short-path distiller. The amount of incoming and outgoing materials is adjusted by adjusting the frequency of the frequency conversion pumps.

[0009] The frequency conversion pump is a gear frequency conversion pump.

[0010] A method for rapid allulose concentration, comprising the following steps: taking an allulose chromatographic extract and performing evaporation treatment in a two-stage short-path distiller to obtain an allulose concentrate.

[0011] Preferably, the heat source for the two-stage short-path distiller is heat-conducting oil.

[0012] Preferably, the allulose chromatographic extract is heated with heat-conducting oil before entering the first-stage short-path distiller.

[0013] Preferably, the evaporation temperature of the heat-conducting oil is 35°C - 46°C.

[0014] Preferably, the vacuum degree of the two-stage short-path distiller is -0.095 MPa to -0.09 MPa. This vacuum degree range takes into account both the equipment cost in large-scale production and the evaporation effect of allulose.

[0015] Preferably, the temperature of the cooling water in the two-stage short-path distiller is 20°C - 25°C.

[0016] Preferably, the rotational speed of the scraper rotor motor of the two-stage short-path distiller is set to 200 - 350 r / min.

[0017] The above solution of the present invention has at least the following beneficial effects: Molecular distillation technology is a special liquid-liquid separation technology. Its separation principle is mainly based on the difference in the average free path of molecular motion of different substances. Different types of molecules have different average free paths due to their different effective molecular diameters. Light molecules have a larger average free path, while heavy molecules have a smaller average free path. When a liquid mixture flows along a heating plate and is heated, light and heavy molecules escape from the liquid surface into the gas phase. Due to the different average free paths of light and heavy molecules, the flight distance of light molecules after escaping from the liquid surface is farther, while that of heavy molecules is closer. Light molecules can reach the condensation plate and be condensed and discharged, while heavy molecules cannot reach the condensation plate and thus are discharged along the heating plate, achieving the separation of substances. Since, compared with other distillation separation methods, light molecules can be condensed after flying a very short distance, molecular distillation is also called short-path distillation. When molecular distillation technology is carried out in a high-vacuum environment, the collision between molecules is reduced, making it easier for molecules to escape from the liquid surface and reach the condensation plate, thereby improving the separation efficiency. Molecular distillation technology utilizes the difference in the average free path of molecular motion of different substances, especially in a high-vacuum environment, to achieve a more efficient and low-temperature separation process, and has a better separation effect for the separation of thermosensitive substances such as allulose. It achieves the purpose of rapid concentration and rapid discharging of allulose.

[0018] The BX after concentration of the allulose concentrate obtained by the molecular distillation technology of the present invention is 75%-85%, the color value is 5-10 IU, the purity is >98%, the allulose does not decompose, and the purity does not change. It improves the subsequent crystallization effect and crystallization recovery rate. Moreover, the color value of the mother liquor after crystallization is greatly reduced, reducing the industrial production cost caused by the decolorization of materials due to pigment accumulation when the mother liquor is recycled. Brief Description of the Drawings

[0019] Figure 1 It is a schematic structural diagram of the allulose rapid concentration system of the present invention.

[0020] Among them, 1. raw material tank; 2. raw material tank liquid level gauge; 3. primary feeding variable frequency pump; 4. primary feeding flowmeter; 5. sewage discharge valve; 6. primary feeding one-way valve; 7. primary liquid nitrogen trap; 8. primary vacuum pump; 9. primary short-path distiller; 10. pre-concentration buffer tank; 11. pre-concentration buffer tank liquid level gauge; 12. pre-concentration buffer tank thermometer; 13. primary condensate buffer tank; 14. primary condensate buffer tank liquid level gauge; 15. primary short-path distillation variable frequency discharge pump; 16. primary short-path distillation vacuum pressure gauge; 17. primary short-path distillation feeding automatic switch valve; 18. secondary short-path distillation feeding automatic switch valve; 19. secondary scraper rotor motor; 20. secondary short-path distiller; 21. secondary liquid nitrogen trap; 22. secondary vacuum pump; 23. discharge buffer tank; 24. secondary condensate buffer tank; 25. secondary condensate variable frequency pump; 26. secondary discharge variable frequency pump; 27. primary condensate variable frequency pump; 28. condensate storage tank; 29. post-concentration tank; 30. secondary short-path distillation vacuum pressure gauge; 31. primary short-path scraper; 32. secondary short-path scraper; 33. primary scraper rotor motor; 34. primary short-path distillation heat transfer oil digital display thermometer; 35. secondary short-path distillation heat transfer oil digital display thermometer; 36. primary short-path distillation cooling water inlet switch valve; 37. primary short-path distillation cooling water return regulating valve; 38. secondary short-path distillation cooling water inlet switch valve; 39. secondary short-path distillation cooling water return regulating valve; 40. primary cooling water return digital display thermometer; 41. secondary cooling water return digital display thermometer; 42. secondary feeding flowmeter; 43. discharge buffer tank liquid level gauge; 44. secondary feeding one-way valve; 45. secondary condensate buffer tank liquid level gauge. Detailed implementation manners

[0021] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be completely conveyed to those skilled in the art.

[0022] A rapid concentration system for allulose, as Figure 1 shown, mainly includes a raw material tank 1, a primary short-path distiller 9, a pre-concentration buffer tank 10, a secondary short-path distiller 20, and a discharge buffer tank 23. The allulose chromatographic extract enters the primary short-path distiller 9 from the raw material tank 1 for primary distillation. After the obtained pre-concentrated allulose solution enters the pre-concentration buffer tank 10, it then enters the secondary short-path distiller 20 for secondary distillation, and the obtained allulose concentrate enters the discharge buffer tank 23.

[0023] Heat conducting oil pipes are provided on the raw material tank 1, the primary short-path distiller 9, and the secondary short-path distiller 20 as the heating source.

[0024] A vacuum pumping device is provided on the first-stage short-path distiller 9 and the second-stage short-path distiller 20. The vacuum pumping device includes a liquid nitrogen trap and a vacuum pump. The liquid nitrogen trap is connected to the distillation chamber of the short-path distiller through a pipeline, and the vacuum pump is connected to the liquid nitrogen trap through a pipeline.

[0025] Frequency conversion pumps are provided on the pipelines between the raw material tank 1 and the first-stage short-path distiller 9, and between the pre-concentration buffer tank 10 and the second-stage short-path distiller 20. The feeding and discharging amount is adjusted by adjusting the frequency of the frequency conversion pump. The frequency conversion pump is a gear frequency conversion pump.

[0026] The first-stage feeding frequency conversion pump 3, the first-stage short-path distillation variable-frequency discharging pump 15, the first-stage condensate water frequency conversion pump 27, the second-stage condensate water frequency conversion pump 25, and the second-stage discharging frequency conversion pump 26 are all gear frequency conversion pumps.

[0027] The first-stage feeding one-way valve 6 and the second-stage feeding one-way valve 44 ensure the unidirectional flow of materials. Example 1

[0028] By using the above system, rapid concentration of allulose is carried out, including the following steps: taking the allulose chromatographic extraction solution with a Brix of 15%-20% and performing evaporation treatment in the two-stage short-path distiller to obtain the allulose concentrated solution.

[0029] The specific steps for the evaporation treatment of the allulose chromatographic extraction solution in the two-stage short-path distiller are as follows: Step 1: The heat transfer oil station starts to supply heat transfer oil to the raw material tank 1, the first-stage short-path distiller 9, and the second-stage short-path distiller 20. The temperature of the heat transfer oil is set at 35°C. Observe the digital display thermometer 34 for the heat transfer oil in the first-stage short-path distillation and the digital display thermometer 35 for the heat transfer oil in the second-stage short-path distillation, and keep the digital display temperature constant without large fluctuations; open the first-stage short-path distillation cooling water inlet on-off valve 36, adjust the opening degree of the first-stage short-path distillation cooling water return regulating valve 37, open the second-stage short-path distillation cooling water inlet on-off valve 38, adjust the opening degree of the second-stage short-path distillation cooling water return regulating valve 39, observe the digital display thermometer 40 for the first-stage cooling water return and the digital display thermometer 41 for the second-stage cooling water return, and control the temperature at 20°C - 25°C without large fluctuations.

[0030] Step 2: The allulose raw material is transported to the raw material tank 1, and the liquid level gauge 2 of the raw material tank is observed. The raw material in the raw material tank is kept at 50% of the tank liquid level.

[0031] Step 3: Liquid nitrogen is added to the first-stage liquid nitrogen trap 7 and the second-stage liquid nitrogen trap 21. The first-stage vacuum pump 8 and the second-stage vacuum pump 22 are turned on. Observe the first-stage short-path distillation vacuum pressure gauge 16 and the second-stage short-path distillation vacuum pressure gauge 30, and control the vacuum degree to be stably maintained at -0.095 Mpa.

[0032] Step 4: Open the first-stage feed one-way valve 6 and the first-stage short-path distillation feed automatic switch valve 17. Turn on the first-stage feed variable-frequency pump 3. After the material enters the first-stage short-path distiller 9, turn on the first-stage scraper rotor motor 33 with the rotation speed set at 200 - 350 r / min to drive the first-stage short-path scraper 31 to rotate in the distillation chamber, evenly spreading the material on the inner wall of the first-stage short-path distiller 9. As the scraper rotates, the material also starts to distill. At the same time, observe the first-stage feed flowmeter 4 and control the feed rate to be constant. The feed rate can be adjusted by changing the frequency of the first-stage feed variable-frequency pump 3.

[0033] Step 5: After the material enters the first-stage short-path distiller 9, it starts to evaporate. Observe the liquid level gauge 14 of the first-stage condensate buffer tank. After the condensate enters the first-stage condensate buffer tank 13, turn on the first-stage condensate variable-frequency pump 27; the condensate enters the condensate storage tank 28.

[0034] Step 6: Observe the liquid level gauge 11 and the thermometer 12 of the pre-concentration buffer tank. After the pre-concentrated material enters the pre-concentration buffer tank 10, open the second-stage feed one-way valve 44 and the second-stage short-path distillation feed automatic switch valve 18. Turn on the first-stage short-path distillation variable-frequency discharge pump 15. After the material enters the second-stage short-path distiller 20, turn on the second-stage scraper rotor motor 19 with the rotation speed set at 200 - 350 r / min to drive the second-stage short-path scraper 32 to rotate in the distillation chamber, evenly spreading the material on the inner wall of the second-stage short-path distiller 20. As the scraper rotates, the material undergoes final evaporation and concentration. Observe the second-stage feed flowmeter 42 and control the feed rate to be constant. The feed rate can be adjusted by changing the frequency of the first-stage short-path distillation variable-frequency discharge pump 15.

[0035] Step 7: After the material enters the second-stage short-path distiller, it starts to evaporate. Observe the liquid level gauge 45 of the second-stage condensate buffer tank. After the condensate enters the second-stage condensate buffer tank 24, turn on the second-stage condensate variable-frequency pump 25; the condensate enters the condensate storage tank 28.

[0036] Step 8: Observe the liquid level gauge 43 of the discharge buffer tank. After the material enters the discharge buffer tank 23, turn on the second-stage discharge variable-frequency pump 26, and the material enters the concentrated tank 29 through the pipeline. The obtained concentrated liquid has a Brix of 75% - 85%.

[0037] Step 9: When shutting down, the closing sequence is to turn off the first-stage vacuum pump 8, the second-stage vacuum pump 22, turn off the first-stage scraper rotor motor 33 and the second-stage scraper rotor motor 19, close all the inlet and outlet of the heat transfer oil, turn off all the variable-frequency pumps. After the temperature drops to room temperature, close all the inlet and return valves of the cooling water, and open the drain valve 5 to discharge the residual material in the pipeline.

[0038] After the system stabilizes, determine the time from feeding to discharging, and detect the change in the color value and purity of allulose. Example 2

[0039] By using the above system, rapid concentration of allulose is carried out, including the following steps: taking an allulose chromatographic extraction solution with a Brix of 15%-20%, and performing evaporation treatment in a two-stage short-path distiller to obtain an allulose concentrate.

[0040] The specific steps for the evaporation treatment of the allulose chromatographic extraction solution in the two-stage short-path distiller are as follows: Step 1: The heat transfer oil station starts to supply heat transfer oil to the raw material tank 1, the first-stage short-path distiller 9, and the second-stage short-path distiller 20. The temperature of the heat transfer oil is set at 46°C. Observe the digital display thermometer 34 for the heat transfer oil in the first-stage short-path distillation and the digital display thermometer 35 for the heat transfer oil in the second-stage short-path distillation, and keep the digital display temperature constant without significant fluctuations. Open the inlet switch valve 36 for the cooling water in the first-stage short-path distillation, adjust the opening size of the return regulating valve 37 for the cooling water in the first-stage short-path distillation, open the inlet switch valve 38 for the cooling water in the second-stage short-path distillation, adjust the opening size of the return regulating valve 39 for the cooling water in the second-stage short-path distillation, observe the digital display thermometer 40 for the return cooling water in the first stage and the digital display thermometer 41 for the return cooling water in the second stage, and control the temperature at 20°C - 25°C without significant fluctuations.

[0041] Step 2: The allulose raw material is transported to the raw material tank 1, and observe the liquid level gauge 2 of the raw material tank. Keep the raw material in the raw material tank 1 at 50% of the tank liquid level.

[0042] Step 3: Add liquid nitrogen to the first-stage liquid nitrogen trap 7 and the second-stage liquid nitrogen trap 21. Open the first-stage vacuum pump 8 and the second-stage vacuum pump 22, observe the vacuum pressure gauge 16 for the first-stage short-path distillation and the vacuum pressure gauge 30 for the second-stage short-path distillation, and control the vacuum degree to be stably maintained at -0.09 Mpa.

[0043] Step 4: Open the first-stage feed check valve 6 and the first-stage short-path distillation feed automatic switch valve 17. Open the first-stage feed variable-frequency pump 3. When the material enters the first-stage short-path distiller 9, open the first-stage scraper rotor motor 33, and set the rotation speed at 200 - 350 r / min to drive the first-stage short-path scraper 31 to rotate in the distillation chamber, evenly smear the material on the inner wall of the first-stage short-path distiller 9. As the scraper rotates, the material also starts to distill. At the same time, observe the first-stage feed flowmeter 4 and control the feed rate to be constant. The feed rate can be adjusted by adjusting the frequency of the first-stage feed variable-frequency pump 3.

[0044] Step 5: After the material enters the first-stage short-path distiller 9, evaporation starts. Observe the liquid level gauge 14 of the first-stage condensate buffer tank. After the condensate enters the first-stage condensate buffer tank 13, open the first-stage condensate variable-frequency pump 27; the condensate enters the condensate storage tank 28.

[0045] Step 6: Observe the liquid level gauge 11 of the pre-concentration buffer tank and the thermometer 12 of the pre-concentration buffer tank. After the pre-concentrated material enters the pre-concentration buffer tank 10, open the secondary feed check valve 44 and the automatic on-off valve 18 for the secondary short-path distillation feed. Turn on the variable-frequency discharge pump 15 of the primary short-path distillation. When the material enters the secondary short-path distiller 20, turn on the secondary scraper rotor motor 19, set the rotation speed to 200 - 350 r / min, drive the secondary short-path scraper 32 to rotate in the distillation chamber, evenly smear the material on the inner wall of the secondary short-path distiller 20. As the scraper rotates, the material undergoes final evaporation and concentration. Observe the secondary feed flowmeter 42 and control the feed rate to be constant. The feed rate can be adjusted by regulating the frequency of the variable-frequency discharge pump 15 of the primary short-path distillation.

[0046] Step 7: Once the material enters the secondary short-path distiller, evaporation begins. Observe the liquid level gauge 45 of the secondary condensate buffer tank. After the condensate enters the secondary condensate buffer tank 24, turn on the secondary condensate variable-frequency pump 25; the condensate enters the condensate storage tank 28.

[0047] Step 8: Observe the liquid level gauge 43 of the discharge buffer tank. After the material enters the discharge buffer tank 23, turn on the secondary discharge variable-frequency pump 26, and the material enters the post-concentration tank 29 through the pipeline. The obtained concentrated solution has a Brix of 75% - 85%.

[0048] Step 9: When shutting down, the closing sequence is to turn off the primary vacuum pump 8, the secondary vacuum pump 22, turn off the primary scraper rotor motor 33 and the secondary scraper rotor motor 19, close all the inlet and outlet of the heat transfer oil, turn off all the variable-frequency pumps. After the temperature drops to normal temperature, close all the inlet and return valves of the cooling water, and open the drain valve 5 to discharge the residual material in the pipeline.

[0049] After the system is stable, determine the time from feeding to discharging, and detect the change of the color value and purity of allulose. Example 3

[0050] By using the above system, rapid concentration of allulose is carried out, including the following steps: Take the chromatographic extract of allulose with a Brix of 15% - 20% and perform evaporation treatment in a two-stage short-path distiller to obtain a concentrated solution of allulose.

[0051] The specific steps for the chromatographic extract of allulose to perform evaporation treatment in a two-stage short-path distiller are as follows: Step 1: The heat transfer oil station starts to supply heat transfer oil to the raw material tank 1, the first-stage short-path distiller 9, and the second-stage short-path distiller 20. The temperature of the heat transfer oil is set at 40°C. Observe the digital thermometer 34 for the heat transfer oil in the first-stage short-path distillation and the digital thermometer 35 for the heat transfer oil in the second-stage short-path distillation, and keep the digital temperature constant without significant fluctuations. Open the on-off valve 36 for the cooling water inlet of the first-stage short-path distillation, adjust the opening of the regulating valve 37 for the cooling water return of the first-stage short-path distillation, open the on-off valve 38 for the cooling water inlet of the second-stage short-path distillation, adjust the opening of the regulating valve 39 for the cooling water return of the second-stage short-path distillation, observe the digital thermometer 40 for the cooling water return of the first stage and the digital thermometer 41 for the cooling water return of the second stage, and control the temperature at 20°C - 25°C without significant fluctuations.

[0052] Step 2: The allulose raw material is transported to the raw material tank 1. Observe the liquid level gauge 2 of the raw material tank, and keep the raw material in the raw material tank 1 at 50% of the tank liquid level.

[0053] Step 3: Add liquid nitrogen into the first-stage liquid nitrogen trap 7 and the second-stage liquid nitrogen trap 21. Open the first-stage vacuum pump 8 and the second-stage vacuum pump 22. Observe the vacuum pressure gauge 16 for the first-stage short-path distillation and the vacuum pressure gauge 30 for the second-stage short-path distillation, and control the vacuum degree to be stably maintained at -0.093 Mpa.

[0054] Step 4: Open the first-stage feed check valve 6 and the automatic on-off valve 17 for the first-stage short-path distillation feed. Open the first-stage feed variable-frequency pump 3. When the material enters the first-stage short-path distiller 9, open the first-stage scraper rotor motor 33, set the rotation speed at 200 - 350 r / min, drive the first-stage short-path scraper 31 to rotate in the distillation chamber, evenly coat the material on the inner wall of the first-stage short-path distiller 9, and as the scraper rotates, the material also starts to distill. At the same time, observe the first-stage feed flowmeter 4, control the feed rate to be constant, and adjust the feed rate by adjusting the frequency of the first-stage feed variable-frequency pump 3.

[0055] Step 5: After the material enters the first-stage short-path distiller 9, it starts to evaporate. Observe the liquid level gauge 14 of the first-stage condensate buffer tank. After the condensate enters the first-stage condensate buffer tank 13, open the first-stage condensate variable-frequency pump 27; the condensate enters the condensate storage tank 28.

[0056] Step 6: Observe the liquid level gauge 11 of the pre-concentration buffer tank and the thermometer 12 of the pre-concentration buffer tank. After the pre-concentrated material enters the pre-concentration buffer tank 10, open the second-stage feed check valve 44 and the second-stage short-path distillation feed automatic switch valve 18, and turn on the first-stage short-path distillation variable-frequency discharge pump 15. When the material enters the second-stage short-path distiller 20, turn on the second-stage scraper rotor motor 19, and set the rotation speed to 200 - 350 r / min to drive the second-stage short-path scraper 32 to rotate in the distillation chamber, evenly spreading the material on the inner wall of the second-stage short-path distiller 20. As the scraper rotates, the material undergoes final evaporation and concentration. Observe the second-stage feed flowmeter 42 and control the feed rate to be constant. The feed rate can be adjusted by adjusting the frequency of the first-stage short-path distillation variable-frequency discharge pump 15.

[0057] Step 7: Once the material enters the second-stage short-path distiller, evaporation begins. Observe the liquid level gauge 45 of the second-stage condensate buffer tank. After the condensate enters the second-stage condensate buffer tank 24, turn on the second-stage condensate variable-frequency pump 25; the condensate enters the condensate storage tank 28.

[0058] Step 8: Observe the liquid level gauge 43 of the discharge buffer tank. After the material enters the discharge buffer tank 23, turn on the second-stage discharge variable-frequency pump 26, and the material enters the post-concentration tank 29 through the pipeline. The obtained concentrated liquid has a Brix of 75% - 85%.

[0059] Step 9: When shutting down, the closing sequence is to turn off the first-stage vacuum pump 8, the second-stage vacuum pump 22, turn off the first-stage scraper rotor motor 33 and the second-stage scraper rotor motor 19, close all heat-conducting oil inlets and outlets, turn off all variable-frequency pumps, and after the temperature drops to normal temperature, close all cooling water inlet and return valves, and open the drain valve 5 to discharge the residual material in the pipeline.

[0060] After the system stabilizes, determine the time from feeding to discharging, and detect the change in the color value and purity of allulose.

[0061] It should be noted that the above steps can be controlled through the DCS control system. The liquid levels of each storage tank, the temperature, pressure, inlet and outlet flow rates within the system, and the start and stop of each power pump are adjusted through the PID of the DCS. Comparative Example 1

[0062] Taking the triple-effect tubular evaporator as an example for the existing evaporation and concentration of allulose, the raw material Brix is 15% - 20%, the temperature of the first-effect evaporation chamber is 70°C - 75°C, the temperature of the second-effect evaporation chamber is 65°C - 70°C, the temperature of the third-effect evaporation chamber is 60°C - 65°C. After evaporation and concentration to a Brix of 75% - 85%, discharge from the second effect. After the system stabilizes, determine the time from feeding to discharging, and detect the change in the color value and purity of allulose. Comparative Example 2

[0063] Lower the evaporation temperature, increase the number of effect bodies, and increase the evaporation and concentration of allulose to four-effect evaporation. The raw material Bx is 15%-20%. The temperature of the first-effect evaporation chamber is 65°C-70°C, the temperature of the second-effect evaporation chamber is 60°C-65°C, the temperature of the third-effect evaporation chamber is 55°C-60°C, and the temperature of the fourth-effect evaporator is 50°C-55°C. After evaporation and concentration to a Bx of 75%-85%, discharge from the third effect. After the system is stable, determine the time from feeding to discharging, and detect the changes in the color value and purity of allulose.

[0064] The test results of Examples 1-3 and Comparative Examples 1 and 2 are compared as shown in the following table:

[0065] As can be seen from the above table, by using the molecular distillation technology of the present invention, the color value of the chromatographic extract of allulose after concentration does not increase, the purity is basically maintained, and the discharging time is greatly shortened.

[0066] It is known by common technical knowledge that the present invention can be implemented by other embodiments that do not depart from its spirit or essential characteristics. Therefore, the above-disclosed embodiments are illustrative in all aspects and are not the only ones. All changes within the scope of the present invention or within the scope equivalent to the present invention are encompassed by the present invention.

Claims

1. A rapid concentration system for allulose, characterized in that, It includes a raw material tank, a primary short-path distiller, a pre-concentration buffer tank, a secondary short-path distiller and a discharge buffer tank. The allulose chromatographic extract enters the primary short-path distiller from the raw material tank. The pre-concentrated allulose solution obtained after the primary distillation enters the pre-concentration buffer tank and then enters the secondary short-path distiller for secondary distillation to obtain the allulose concentrate, which enters the discharge buffer tank.

2. The psicose rapid concentration system according to claim 1, characterized in that, Heat-conducting oil pipes are provided as heating sources on the raw material tank, the primary short-path distiller and the secondary short-path distiller.

3. The psicose rapid concentration system according to claim 1, characterized in that, Vacuum pumping devices are provided on the primary short-path distiller and the secondary short-path distiller. The vacuum pumping devices include a liquid nitrogen trap and a vacuum pump. The liquid nitrogen trap is connected to the distillation chamber of the short-path distiller through a pipeline, and the vacuum pump is connected to the liquid nitrogen trap through a pipeline.

4. A method for rapid concentration of allulose, characterized in that, It includes the following steps: taking the allulose chromatographic extract and performing evaporation treatment in the two-stage short-path distiller to obtain the allulose concentrate. The heat source for the two-stage short-path distiller is heat-conducting oil.

5. The method for rapid concentration of allulose according to claim 4, characterized in that The allulose chromatographic extract is heated with heat-conducting oil before entering the primary short-path distiller.

6. The method for rapid concentration of allulose according to claim 5, wherein The evaporation temperature of the heat-conducting oil is 35°C - 46°C.

7. The method for rapid concentration of allulose according to claim 4, wherein The vacuum degree of the two-stage short-path distiller is -0.095 MPa to -0.09 MPa.

8. The method for rapid concentration of allulose according to claim 4, wherein The temperature of the cooling water in the two-stage short-path distiller is 20°C - 25°C.

9. The method for rapid concentration of allulose according to claim 4, characterized in that, The rotational speed of the scraper rotor motor of the two-stage short-path distiller is set to 200 - 350 r / min.

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