A continuous crystallizer for producing crystalline trehalose and a crystallization method thereof

Abstract

The present application relates to the technical field of crystalline trehalose, and particularly relates to a continuous crystallizer for producing crystalline trehalose and a crystallization method thereof, which comprises the following steps: obtaining the amplitude of ultrasonic reflection wave of an ion exchange resin column; determining the feeding flow of trehalose concentrated solution based on the first conductivity value at the outlet of a liquid collecting cavity; continuously injecting the trehalose concentrated solution into the inlet of the ion exchange resin column according to the feeding flow, and obtaining the second conductivity value at the outlet of the liquid collecting cavity; re-determining the feeding flow of the trehalose concentrated solution according to the second conductivity value; obtaining the microcrystalline content at the outlet of the liquid collecting cavity; determining the crystallization temperature of the corresponding crystallization tank based on the microcrystalline content; crystallizing the desalted trehalose concentrated solution according to the crystallization temperature, and sequentially performing crystal slurry separation, mother liquor recovery and drying on the crystal slurry obtained after crystallization, so as to obtain the finished product of crystalline trehalose. The present application realizes the improvement of the crystallization quality of the finished product of crystalline trehalose.

Description

Technical Field

[0001] This invention relates to the field of trehalose crystallization technology, and more particularly to a continuous crystallizer and crystallization method for producing trehalose crystallization. Background Technology

[0002] Trehalose is a natural non-reducing disaccharide with excellent moisturizing, stability, and stress resistance properties. It is widely used in food preservation, pharmaceutical preparations, and cosmetic moisturizing. The core step in crystalline trehalose production is crystallization; the efficiency and quality of the crystallization process directly determine the purity, crystal morphology, and production cost of the final product. Currently, trehalose crystallization mainly uses batch crystallizers or ordinary continuous crystallizers. Existing continuous crystallizers lack effective seed crystal recycling and mother liquor recovery systems. In the feed pretreatment stage, current technologies typically only use simple filtration or single-stage ion exchange desalination. However, trehalose concentrate... High osmotic pressure, and the local blockage or damage to the support layer at the bottom of the resin column, such as stainless steel mesh or quartz sand pad, can cause fluid to flow off-center at the bottom. The resin in the off-center zone experiences a different flow velocity than the main body, generating additional shear stress and promoting the formation of internal microcracks. These microcracks are difficult to detect in the early stages. As the operating time increases and the concentration of trehalose concentrate changes, the cracks are filled with trehalose crystals, forming an ion slow-release reservoir, which leads to a false decrease in the conductivity of the effluent and affects the desalination stability. Therefore, there is an urgent need for a continuous crystallizer and crystallization method for producing crystalline trehalose.

[0003] Chinese Patent Publication No. CN118440126A discloses a method for separating and purifying trehalose, comprising: microfiltration of the raw solution to be treated; desalting the filtrate using an ion exchange resin column; nanofiltration of the desalted solution; first concentration and first crystallization of the membrane concentrated phase to obtain a first crystallization mother liquor and a first crystal; recrystallization and drying of the first crystal to obtain a qualified trehalose product; combining the recrystallized mother liquor into the next batch of membrane concentrated phase; second concentration and second crystallization of the first crystallization mother liquor to obtain a second crystallization mother liquor and a second crystal; dissolving the second crystal in water and combining it into the next batch of membrane concentrated phase; combining the second crystallization mother liquor into the next batch of raw solution to be treated to extract trehalose, or using the second crystallization mother liquor in the production process of other fermented products; Therefore, the method for separating and purifying trehalose has the following problems: when the support layer at the bottom of the ion exchange resin column is blocked, the trehalose concentrate forms a bias flow at the bottom, which in turn causes additional shear stress and osmotic pressure gradient in the resin in the bias flow zone, resulting in microcracks. This leads to a decrease in the accuracy of monitoring the desalination effect of the resin column, and the intermittent release of trehalose crystal particles inside the microcracks reduces the stability of desalination. Summary of the Invention

[0004] Therefore, the present invention provides a continuous crystallizer and crystallization method for producing crystalline trehalose, which overcomes the problems in the prior art where the trehalose concentrate forms a bias flow at the bottom due to blockage of the support layer at the bottom of the ion exchange resin column, resulting in additional shear stress and osmotic pressure gradient in the resin in the bias flow zone, which in turn generates microcracks, reducing the accuracy of monitoring the desalination effect of the resin column, and causing the intermittent release of trehalose crystal particles inside the microcracks, which reduces the stability of desalination.

[0005] On one hand, the present invention provides a continuous crystallization method for producing crystalline trehalose, comprising: The pre-filtered trehalose concentrate was injected into the inlet of the ion exchange resin column to desalinate the trehalose concentrate. The amplitude of the ultrasonic reflected wave of the ion exchange resin column during the injection process of trehalose concentrate was obtained; The feed flow rate of the trehalose concentrate is determined based on the first conductivity value of the trehalose concentrate at the outlet of the collection chamber below the ion exchange resin column within the conductivity monitoring period that meets the preset amplitude conditions. The trehalose concentrate is continuously injected into the inlet of the ion exchange resin column according to the feed flow rate, and the second conductivity value of the trehalose concentrate at the outlet of the collection chamber below the ion exchange resin column is obtained during the desalination process after a preset duration. The feed flow rate of the trehalose concentrate was re-determined based on the second conductivity value; The desalination of the trehalose concentrate was completed according to the redefined feed flow rate, and the microcrystal content in the trehalose concentrate at the outlet of the collection chamber below the ion exchange resin column was obtained. The crystallization temperature of the corresponding crystallizer is determined based on the microcrystal content. The desalted trehalose concentrate was crystallized at the specified crystallization temperature, and the resulting crystal slurry was subjected to crystal slurry separation, mother liquor recovery, and drying in sequence to obtain the crystallized trehalose product.

[0006] Further, determining the feed flow rate of the trehalose concentrate based on the first conductivity value at the outlet of the collection chamber below the ion exchange resin column within a conductivity monitoring period that meets preset amplitude conditions includes: Compare the first conductivity value with a preset first conductivity value; If the first conductivity value is less than the preset first conductivity value, it is determined that the effect of the microcracks at the bottom of the ion exchange resin column on the desalination effect of the resin column does not meet the requirements, and the feed flow rate of the trehalose concentrate is reduced. The preset amplitude condition is that the amplitude is greater than the preset amplitude within a unit amplitude monitoring period.

[0007] Furthermore, the feed flow rate is positively correlated with the first conductivity value.

[0008] Further, the step of redetermining the feed flow rate of the trehalose concentrate based on the second conductivity value includes: The second conductivity value is compared with a preset second conductivity value; If the second conductivity value is greater than the preset second conductivity value, it is determined that the intermittent release of ions encapsulated by trehalose crystals inside the microcracks has a negative impact on the desalination stability of the resin column, and the feed flow rate of the trehalose concentrate is increased.

[0009] Furthermore, the feed flow rate is positively correlated with the second conductivity value.

[0010] Further, determining the crystallization temperature of the corresponding crystallizer based on the microcrystal content includes: The microcrystal content is compared with the preset microcrystal content; If the microcrystal content is greater than the preset microcrystal content, it is determined that the impact on the uniformity of crystal size due to the shedding of trehalose microcrystals from the microcrack area of ​​the resin column does not meet the requirements, and the crystallization temperature of the corresponding crystallizer is reduced. The microcrystal content is the ratio of the volume of crystals with a diameter smaller than a preset diameter in the effluent at the outlet of the ion exchange resin column to the total volume of the effluent.

[0011] Furthermore, the crystallization temperature is negatively correlated with the microcrystal content.

[0012] Furthermore, the corresponding crystallizer is the crystallizer with the shortest material transport path between it and the ion exchange resin column.

[0013] On the other hand, the present invention provides a continuous crystallizer for producing crystalline trehalose, comprising: The feed pretreatment module is used to filter trehalose concentrate, including a ceramic membrane filter for preliminary filtration of trehalose concentrate to output trehalose concentrate, an ion exchange resin column connected to the ceramic membrane filter for desalination of trehalose concentrate, and a support layer disposed below the ion exchange resin column to provide support to the ion exchange resin column. A continuous crystallization module, which is connected to the feed pretreatment module, is used to continuously crystallize the desalted trehalose concentrate. It includes a concentration regulating tank connected to the liquid collection chamber outlet of the support layer for adjusting the concentration of the desalted material to be crystallized, and a crystallization separation component for continuous crystallization and post-crystallization treatment to output the crystallized trehalose product. The detection module is connected to the feed pretreatment module and the continuous crystallization module respectively, and is used to obtain the amplitude of the ultrasonic reflected wave of the ion exchange resin column, the first conductivity value of the trehalose concentrate at the outlet of the collection chamber below the ion exchange resin column within the conductivity monitoring period that meets the preset amplitude conditions, the second conductivity value of the trehalose concentrate at the outlet of the collection chamber during the desalination process after a preset duration, and the microcrystal content in the trehalose concentrate at the outlet of the collection chamber. A control module, which is connected to the detection module, the feed pretreatment module and the continuous crystallization module respectively, is used to determine the feed flow rate of trehalose concentrate based on the amplitude and the first conductivity value, redetermine the feed flow rate based on the second conductivity value, and determine the crystallization temperature of the corresponding crystallizer based on the microcrystal content.

[0014] Furthermore, the crystallization separation component includes: Several crystallization tanks are arranged below the concentration regulating tank, with each individual crystallization tank connected in series vertically to adjacent crystallization tanks, for continuous crystallization of the material to be crystallized; A spiral centrifuge, connected to the outlet of the lowest crystallizer among several crystallizers, is used to separate the crystallized slurry to output wet crystals and mother liquor. A seed activation tank is connected to the corresponding outlet of the wet crystal of the spiral centrifuge, and is used to activate the wet crystal to output seed crystals; A nanofiltration membrane separator is connected to the corresponding outlet of the mother liquor of the spiral centrifuge to retain trehalose in the mother liquor and output the retentate. The outlet of the seed activation tank is connected to the inlet of the uppermost crystallization tank among the plurality of crystallization tanks via a seed delivery pump and a seed filter; the outlet of the nanofiltration membrane separator is connected to the inlet of the ion exchange resin column via a reflux pipe; the temperature of the crystallization tank decreases vertically from top to bottom.

[0015] Compared with the prior art, the beneficial effect of the present invention is that by reducing the feed flow rate of trehalose concentrate, the present invention solves the problem of flow deviation caused by blockage of the support layer at the bottom of the ion exchange resin column, which in turn causes shear stress on the resin particles at the bottom of the ion exchange resin column, resulting in microcracks at the bottom of the ion exchange resin column. As the trehalose concentrate flows through the contact point between the bottom support layer and the ion exchange resin column, the sieve apertures of the support layer become smaller due to the capture of fine resin powder, leading to local blockage of the support layer. This increases the flow velocity of the trehalose concentrate in the unblocked areas. Since the outflow rate of the trehalose concentrate is constant, the high flow velocity areas generate additional shear stress on the surface of the resin particles in the ion exchange resin column. Simultaneously, the high and low flow velocity areas... The hydrodynamic pressure difference between domains causes uneven stress on the resin particles, leading to stress concentration within the particles and the initiation of microcracks. These microcracks are directly exposed to the high-concentration sugar solution and are rapidly adsorbed and covered by trehalose molecules during the continuous injection of trehalose concentrate. When the inner surface of the microcracks is saturated with adsorption or filled with crystals, the effective exchange area of ​​the ion exchange resin column where the microcracks are located decreases, resulting in insufficient ion exchange effectiveness between the ion exchange resin column and the corresponding ions in the trehalose concentrate. Therefore, by reducing the feed flow rate of the trehalose concentrate, the shear stress of the fluid on the resin particles is reduced, thereby eliminating the velocity difference between high and relatively low flow rates, inhibiting the propagation of microcracks, and further improving the desalination effect of the ion exchange resin column.

[0016] Furthermore, this invention addresses the problem of decreased desalination stability caused by trehalose crystallization filling microcracks and releasing ions during crystallization by redetermining the trehalose concentrate feed flow rate. Specifically, after a preset duration, the feed flow rate is increased when the second conductivity value at the outlet of the collection chamber below the ion exchange resin column exceeds a preset second conductivity value. During the ion exchange resin column's operation, the cracks are gradually filled with trehalose crystals. Impurity ions from the trehalose concentrate within the crystals form an ion slow-release reservoir. When the impurity ions within the crystals become saturated, concentration fluctuations occur due to the mixing of the trehalose concentrate at the ion exchange resin column inlet with the lower-concentration recovered mother liquor. The previously encapsulated impurities... As the concentration of impurity ions fluctuates, they are released back into the feed solution around the cracks. Since the microcracks are located at the bottom of the ion exchange resin column, the released impurity ions flow directly out of the ion exchange resin column with the feed solution without further exchange. Therefore, the released impurity ions cause the second conductivity value at the outlet of the collection chamber below the ion exchange resin column to increase. Thus, by increasing the feed flow rate of the trehalose concentrate, the total amount of ions released from the cracks per unit time remains relatively constant. Increasing the feed flow rate dilutes the released ions into a larger volume, thereby reducing the ion concentration in the effluent. Therefore, increasing the feed flow rate within the allowable flow rate adjustment range suppresses the increase in effluent conductivity caused by the intermittent release of impurity ions, further improving desalination stability.

[0017] Furthermore, this invention addresses the decrease in crystallization uniformity caused by trehalose microcrystals detaching from the microcracks in the resin column by reducing the crystallization temperature of the crystallizer with the shortest material transport path between the crystallizer and the ion exchange resin column. As the trehalose crystals filling the microcracks accumulate to a certain extent, the expansion stress between the growing crystals and the crack walls causes the trehalose microcrystals to detach from the cracks and enter the crystallizer containing larger crystals that remain in the crystallizer during continuous crystallization. These harder trehalose microcrystals have smaller particle sizes compared to conventional trehalose crystals, and the supersaturated trehalose solution in the crystallizer will... Trehalose microcrystals preferentially grow on existing solid surfaces. After entering the crystallization tank, they become secondary crystal nuclei, providing a growth surface for the supersaturated trehalose solution. This causes solutes in the solution to preferentially deposit on these microcrystals, thereby inducing the formation of excessive fine crystals, which affects the product's flowability, filtration performance, and final quality. Therefore, this invention increases the supersaturation of the supersaturated trehalose solution by lowering the corresponding crystallization tank temperature, promoting the growth rate of fine crystals. At the same time, the high supersaturation environment created by the lower crystallization temperature inhibits the random formation of new crystal nuclei, further improving the uniformity of crystal particle size distribution, and ultimately improving the quality of the finished crystallized trehalose. Attached Figure Description

[0018] Figure 1This is an overall flow chart of the continuous crystallization method for producing crystalline trehalose according to an embodiment of the present invention; Figure 2 This is a flowchart illustrating the process of re-determining the feed flow rate of trehalose concentrate in a continuous crystallization method for producing crystalline trehalose according to an embodiment of the present invention. Figure 3 This is a flowchart illustrating the determination of the crystallization temperature of the corresponding crystallization tank in a continuous crystallization method for producing crystalline trehalose according to an embodiment of the present invention. Figure 4 This is a schematic diagram of the ion exchange resin column and support layer used in a continuous crystallizer for producing crystalline trehalose according to an embodiment of the present invention; 1-Ion exchange resin column, 2-Inlet of ion exchange resin column, 3-Outlet of collection chamber, 4-Screen, 5-Quartz sand pad, 6-Collection chamber. Detailed Implementation

[0019] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0020] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0021] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0022] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0023] Please see Figure 1 and Figure 4The diagram shows an overall flow chart of the continuous crystallization method for producing crystalline trehalose according to an embodiment of the present invention, and a structural schematic diagram of the ion exchange resin column and support layer of the continuous crystallizer for producing crystalline trehalose. The continuous crystallization method for producing crystalline trehalose according to an embodiment of the present invention includes: S1, the trehalose concentrate that has undergone preliminary filtration is injected into the inlet 2 of the ion exchange resin column to desalinate the trehalose concentrate. S2, obtain the amplitude of the ultrasonic reflected wave of the ion exchange resin column 1 during the injection process of trehalose concentrate; S3, the feed flow rate of the trehalose concentrate is determined based on the first conductivity value of the trehalose concentrate at the outlet 3 of the collection chamber below the ion exchange resin column within the conductivity monitoring period that meets the preset amplitude conditions. S4, continue to inject the trehalose concentrate into the inlet of the ion exchange resin column according to the feed flow rate, and obtain the second conductivity value of the trehalose concentrate at the outlet of the collection chamber below the ion exchange resin column during the desalination process after a preset duration. S5, redetermine the feed flow rate of the trehalose concentrate based on the second conductivity value; S6, complete the desalination of trehalose concentrate according to the re-determined feed flow rate, and obtain the microcrystal content in trehalose concentrate at the outlet of the collection chamber below the ion exchange resin column. S7, determine the crystallization temperature of the corresponding crystallizer based on the microcrystal content; S8. The desalted trehalose concentrate is crystallized at the crystallization temperature, and the crystal slurry obtained after crystallization is sequentially separated, the mother liquor is recovered and dried to obtain the crystallized trehalose product.

[0024] In step S1, the ion types in the trehalose concentrate removed during the desalination process include: calcium ions, magnesium ions, potassium ions, sodium ions, chloride ions, sulfate ions, and phosphate ions.

[0025] The conductivity of the desalted trehalose concentrate is less than 8 μS / cm.

[0026] In step S2, the amplitude of the ultrasonic reflected wave of the ion exchange resin column during the injection process of trehalose concentrate is obtained by an ultrasonic transducer installed on the outer wall of the ion exchange resin column. The amplitude of the ultrasonic reflected wave is used to characterize the physical state inside the ion exchange resin column, that is, whether there is flow deviation caused by blockage in the support layer at the bottom of the ion exchange resin column, resulting in microcracks at the bottom of the ion exchange resin column. Under the condition that the material of the ion exchange resin column is styrene-divinylbenzene copolymer and the factory-specified ultrasonic reflected wave amplitude is 600mV, when the ultrasonic amplitude is greater than 1000mV, it indicates that the ion exchange resin column has lost its exchange capacity; when the ultrasonic amplitude is 900mV, it indicates that the support layer at the bottom of the ion exchange resin column has microcracks caused by local blockage. Therefore, a preferred embodiment of the preset amplitude is 900mV. In this embodiment, given that the ion exchange resin column is made of styrene-divinylbenzene copolymer and the factory-calibrated ultrasonic reflection wave amplitude of the ion exchange resin column is 600mV, the preset amplitude can be selected within the range of [600mV, 1000mV]. Those skilled in the art will understand that this determination is based on a specific scenario of this embodiment, and can be adjusted according to specific standard conditions, which will not be elaborated further here.

[0027] Specifically, step S3 includes: Step S31: Compare the first conductivity value with a preset first conductivity value; Step S32: If the first conductivity value is less than the preset first conductivity value, it is determined that the effect of the microcracks at the bottom of the ion exchange resin column on the desalination effect of the resin column does not meet the requirements, and the feed flow rate of the trehalose concentrate is reduced so that the impact of the trehalose concentrate on the ion exchange resin column is reduced, thereby improving the ion exchange effectiveness between the ion exchange resin column and the corresponding ions in the trehalose concentrate.

[0028] If the first conductivity value is less than the preset first conductivity value, it indicates that the ion exchange effectiveness between the ion exchange resin column and the corresponding ions in the trehalose concentrate is insufficient. The greater the difference between the preset first conductivity value and the first conductivity value, the greater the impact of the trehalose concentrate on the ion exchange resin column, which in turn leads to a decrease in the ion exchange effectiveness between the ion exchange resin column and the corresponding ions in the trehalose concentrate.

[0029] The impact force of trehalose concentrate on the ion exchange resin column is determined by the aperture of the screen in the bottom support layer. The smaller the aperture of the screen, the greater the clogging pressure experienced by the trehalose concentrate as it passes through the screen, resulting in a greater liquid pressure of the trehalose concentrate between the ion exchange resin column and the screen, and thus a greater impact force. When the aperture of the screen in the bottom support layer is within the standard aperture range, the liquid pressure of the trehalose concentrate between the ion exchange resin column and the screen is stable, and the impact force of the trehalose concentrate on the ion exchange resin column is normal.

[0030] A preset first conductivity value is used to determine whether the decrease in the first conductivity value at the outlet of the collection chamber below the ion exchange resin column is caused by microcracks. Under the condition that the amplitude of the ultrasonic reflected wave from the ion exchange resin column is greater than the preset amplitude within a unit amplitude monitoring cycle, the conductivity of the trehalose concentrate after normal desalination should be less than 8 μS / cm, and typically between 7 μS / cm and 8 μS / cm during stable operation. When the first conductivity value at the outlet of the collection chamber below the ion exchange resin column is 4 μS / cm, it indicates that the decrease in conductivity is not caused by microcracks, but rather by a conductivity sensor malfunction, abnormal temperature, or a problem with the feed purity. The change in conductivity is caused by a sudden change in conductivity. When the first conductivity value at the outlet of the collection chamber below the ion exchange resin column is 7 μS / cm, it means that the ion exchange resin column is within the normal fluctuation range of stable operation. For example, the selectable range of the preset first conductivity value is [4 μS / cm, 7 μS / cm]. When the first conductivity value at the outlet of the collection chamber below the ion exchange resin column is 6 μS / cm, it means that the conductivity value at the outlet of the collection chamber below the ion exchange resin column has decreased due to the generation of microcracks. Preferably, a preferred embodiment of the preset first conductivity value in this embodiment is 6 μS / cm.

[0031] Specifically, the conductivity monitoring period is 2 hours.

[0032] Specifically, the unit amplitude monitoring period is 60 seconds.

[0033] Specifically, the feed flow rate of the trehalose concentrate is adjusted by a variable frequency feed pump installed on the pipeline at the inlet of the ion exchange resin column.

[0034] In this embodiment, the feed flow rate is positively correlated with the first conductivity value; that is, the lower the first conductivity value, the smaller the reduced feed flow rate. The reduced feed flow rate should be greater than 2.5 m³ / min. 3To prevent uneven feed distribution within the ion exchange resin column due to excessively low trehalose concentrate flow rate, which could lead to a decrease in the overall desalination efficiency of the column, those skilled in the art can adaptively adjust the trehalose concentrate feed rate based on the column's diameter, height, and the decreasing trend of the monitored first conductivity value. The adjusted feed rate is maintained at 2.5 m³ / h. 3 / h to 7.5m 3 The feed rate adjustment should be within the range of / h, and for every 0.1 μS / cm decrease in the first conductivity value, the corresponding feed rate adjustment step should not decrease by more than 0.2 m. 3 / h, to avoid abrupt changes in feed flow rate that could clog the support layer at the bottom of the ion exchange resin column, leading to increased flow deviation; in a specific embodiment, if the first conductivity value at the outlet of the collection chamber below the ion exchange resin column is 5.6 μS / cm during the conductivity monitoring period that meets the preset amplitude conditions, based on the above adjustment principle, the feed flow rate is adjusted by 0.2 m each time. 3 / h, from the current 5m 3 / h until adjusted to 3.6m 3 / h.

[0035] Specifically, the preset duration in step S4 is the time required for the microcrack to be generated and filled with trehalose crystals and reach saturation. In this embodiment, a preferred embodiment of the preset duration is 4 hours.

[0036] Please see Figure 2 As shown, this is a flowchart of the process for re-determining the feed flow rate of trehalose concentrate in a continuous crystallization method for producing crystalline trehalose according to an embodiment of the present invention. Step S5 includes: Step S51: Compare the second conductivity value with a preset second conductivity value; Step S52: If the second conductivity value is greater than the preset second conductivity value, it is determined that the intermittent release of ions encapsulated by trehalose crystals inside the microcracks has a negative impact on the desalination stability of the resin column. Step S53: Increase the feed flow rate of trehalose concentrate so that the released ions are diluted into more trehalose concentrate, thereby reducing the peak ion concentration at the outlet of the collection chamber below the ion exchange resin column. The second conductivity value is greater than the preset second conductivity value, indicating that the crack is gradually filled with trehalose crystals. When the impurity ions inside the crystals are saturated, the saturated ions are released again due to the fluctuation of the feed to the ion exchange resin column, which in turn reduces the desalination stability of the ion exchange resin column.

[0037] The fluctuation in the feed to the ion exchange resin column is determined by the degree of decrease in the flux of the nanofiltration membrane separator during the recovery of mother liquor by the spiral centrifuge in the continuous crystallizer over the operating time. The decrease in the flux of the nanofiltration membrane separator leads to a periodic change in the concentration of the retentate output by the nanofiltration membrane separator. When mixed with the subsequently injected trehalose concentrate, it causes fluctuations in the feed concentration, which in turn leads to the re-release of saturated ions in the microcracks, resulting in a decrease in the desalination stability of the ion exchange resin column. A preset second conductivity value is used to determine whether an increase in the second conductivity value at the outlet of the collection chamber below the ion exchange resin column is caused by the re-release of saturated ions from the cracks. Under the condition that the flux decrease of the nanofiltration membrane separator leads to a variation in the mass fraction of trehalose in the retentate output by the nanofiltration membrane separator ranging from 73% to 76%, a second conductivity value of 10 μS / cm at the outlet of the collection chamber below the ion exchange resin column indicates that the ceramic membrane filter upstream of the ion exchange resin has permeated or leaked, resulting in the introduction of insoluble impurities, proteins, or small particles into the trehalose concentrate. These substances contaminate... The contamination of the ion exchange resin column causes a decrease in desalination efficiency. When the second conductivity value at the outlet of the collection chamber below the ion exchange resin column is 8 μS / cm, it means that the second conductivity value is at the upper limit of the normal qualified range, which is a normal fluctuation in the desalination process. For example, the preset range of the second conductivity value is [8 μS / cm, 10 μS / cm]. When the second conductivity value at the outlet of the collection chamber below the ion exchange resin column is 9 μS / cm, it means that the ion slow-release reservoir in the microcrack has begun to release. Preferably, the preferred embodiment of the preset second conductivity value in this example is 9 μS / cm.

[0038] In this embodiment, the feed flow rate is positively correlated with the second conductivity value; that is, the larger the second conductivity value, the larger the increased feed flow rate. At this point, the microcrack is filled with trehalose crystals and reaches saturation. The hardness of the crystals provides physical support for the crack walls, and the fluid shear stress is insufficient to drive crack propagation. Therefore, the increased feed flow rate should be greater than 3.6 m³ / min. 3 / h and less than 7.5m 3 To prevent insufficient dilution due to excessively low flow rate or inadequate desalination due to excessively high flow rate, those skilled in the art can adaptively adjust the feed flow rate of the trehalose concentrate based on the difference between the second conductivity value and the preset second conductivity value, as well as the monitored upward trend of the second conductivity value. The adjusted feed flow rate is maintained at 3.6 m³ / h. 3 / h to 7.5m 3 The feed rate adjustment should be within the range of / h, and for every 0.2 μS / cm increase in the second conductivity value, the corresponding feed rate adjustment step should not increase by more than 0.1 m. 3 / h, to avoid the impact of sudden changes in feed flow rate on the desalination effect of the ion exchange resin column; in a specific embodiment, the second conductivity value at the outlet of the liquid collection chamber below the ion exchange resin column during the desalination process after a preset duration is 9.4 μS / cm. Based on the above adjustment principle, the feed flow rate is adjusted by 0.1 m each time. 3 / h, until from 3.6m 3 / h adjusted to 3.8m 3 / h.

[0039] Specifically, in step S6, the microcrystal content at the outlet of the collection chamber below the ion exchange resin column is obtained by using an online laser particle size analyzer located at the outlet of the collection chamber below the ion exchange resin column.

[0040] Please see Figure 3 As shown, this is a flowchart illustrating the determination of the crystallization temperature of the corresponding crystallization tank in a continuous crystallization method for producing crystalline trehalose according to an embodiment of the present invention. Step S7 includes: Step S71: Compare the microcrystal content with the preset microcrystal content; Step S72: If the microcrystal content is greater than the preset microcrystal content, it is determined that the effect of the trehalose microcrystals falling off from the microcrack area of ​​the resin column on the uniformity of crystal size does not meet the requirements. Step S73: Reduce the crystallization temperature of the corresponding crystallizer and increase the supersaturation of the corresponding crystallizer. The growth rate of fine crystals is increased by much greater than that of the existing grains in the crystallizer, so that the fine crystals grow rapidly to above the critical size, thereby reducing the number and proportion of fine crystals and improving the uniformity of crystal grain size distribution. The growing crystals generate expansion stress between themselves and the crack walls. This stress is determined by the volume increase of the trehalose crystals within the crack and the degree of constraint of the crack walls. The greater the crystal volume increase and the stronger the rigidity of the crack walls, the greater the expansion stress. This leads to a decrease in the adhesion of trehalose microcrystals from the crack walls. When the adhesion is less than the scouring force of the trehalose concentrate, the microcrystals detach and enter the crystallization tank below, thereby inducing the formation of excessive fine crystals. Wherein, the microcrystal content is the ratio of the volume of crystals with a particle size smaller than a preset diameter in the effluent at the outlet of the ion exchange resin column to the total volume of the effluent.

[0041] The preset microcrystal content is used to determine whether the microcrystals in the effluent are caused by the detachment of resin column microcracks. Under the condition that the ion exchange resin column is operating normally and the upstream ceramic membrane filter is leak-free, when the microcrystal content at the outlet of the collection chamber below the ion exchange resin column is 0.05%, it represents background particles that may exist under normal operating conditions, such as resin fine powder or pipeline impurities. When the microcrystal content at the outlet of the collection chamber below the ion exchange resin column is 0.15%, it represents that the upstream ceramic membrane filter has been penetrated, the resin has broken and produced fine powder, or additional microcrystals have been generated by the backflow of fine crystals in the crystallization tank. For example, the selectable range of the preset microcrystal content is [0.05%, 0.15%]. When the microcrystal content at the outlet of the collection chamber below the ion exchange resin column is 0.1%, after excluding upstream leakage of the ion exchange resin column, it can be determined that trehalose microcrystals have detached from the resin column microcrack area. Preferably, the preferred embodiment of the preset microcrystal content in this example is 0.1%.

[0042] Specifically, the crystallization temperature of the crystallizer is adjusted by a temperature regulating medium regulating valve installed inside the jacket of the crystallizer.

[0043] In this embodiment, the crystallization temperature is negatively correlated with the microcrystal content; that is, the higher the microcrystal content, the lower the adjusted crystallization temperature. To prevent excessively low crystallization temperatures from causing excessive supersaturation of the trehalose concentrate and triggering spontaneous nucleation, or from exceeding the cooling capacity of the cooling jacket, those skilled in the art can adaptively adjust the crystallization temperature of the crystallizer with the shortest material transport path between the crystallizer and the ion exchange resin column based on the jacket heat exchange area, the lowest temperature of the cooling medium in the jacket, and the monitored upward trend of the microcrystal content. The adjusted crystallization temperature should be maintained within the range of 50°C to 58°C. Furthermore, for every 0.02% increase in microcrystal content, the corresponding adjustment step of the crystallization temperature should not decrease by more than 1°C to avoid spontaneous nucleation caused by excessive local supersaturation of the solution due to a sudden drop in temperature. In a specific embodiment, the current microcrystal content is 0.14%. Based on the adjustment principle described above, the crystallization temperature is adjusted by 1°C each time, from the current 58°C to 56°C.

[0044] Specifically, since the supersaturated trehalose solution in the crystallizer will preferentially crystallize on crystal nuclei with a diameter of less than 50 μm, a preferred embodiment of the preset diameter is 50 μm.

[0045] Please continue reading. Figure 4 As shown, an embodiment of the present invention provides a continuous crystallizer for producing crystalline trehalose, comprising: The feed pretreatment module is used to filter trehalose concentrate, including a ceramic membrane filter for preliminary filtration of trehalose concentrate to output trehalose concentrate, an ion exchange resin column 1 connected to the ceramic membrane filter for desalination of trehalose concentrate, and a support layer disposed below the ion exchange resin column to provide support to the ion exchange resin column. A continuous crystallization module, which is connected to the feed pretreatment module, is used to continuously crystallize the desalted trehalose concentrate. It includes a concentration regulating tank connected to the liquid collection chamber outlet of the support layer for adjusting the concentration of the desalted material to be crystallized, and a crystallization separation component for continuous crystallization and post-crystallization treatment to output the crystallized trehalose product. The detection module is connected to the feed pretreatment module and the continuous crystallization module respectively, and is used to obtain the amplitude of the ultrasonic reflected wave of the ion exchange resin column, the first conductivity value at the outlet 3 of the liquid collection chamber below the ion exchange resin column within the conductivity monitoring period that meets the preset amplitude condition, the second conductivity value at the outlet of the liquid collection chamber below the ion exchange resin column during the desalination process after a preset duration, and the microcrystal content at the outlet of the liquid collection chamber below the ion exchange resin column. A control module, which is connected to the detection module, the feed pretreatment module and the continuous crystallization module respectively, is used to determine the feed flow rate of trehalose concentrate based on the amplitude and the first conductivity value, redetermine the feed flow rate based on the second conductivity value, and determine the crystallization temperature of the corresponding crystallizer based on the microcrystal content.

[0046] Specifically, the support layer includes: Quartz sand cushion layer 5 is placed below the ion exchange resin column to achieve uniform distribution of trehalose concentrate through several layers of sand with decreasing particle size. Screen 4 is set below the quartz sand cushion layer to filter resin particles of ion exchange resin and quartz sand. The collection chamber 6 is located below the sieve and is used to collect the trehalose concentrate after desalination.

[0047] Specifically, the crystallization separation component includes: Several crystallization tanks are arranged below the concentration regulating tank, with each crystallization tank connected in series vertically to adjacent crystallization tanks, for continuous crystallization of the material to be crystallized; A spiral centrifuge, connected to the outlet of the lowest crystallizer among several crystallizers, is used to separate the crystallized slurry to output wet crystals and mother liquor. A seed activation tank is connected to the corresponding outlet of the wet crystal of the spiral centrifuge, and is used to activate the wet crystal to output seed crystals; A nanofiltration membrane separator is connected to the corresponding outlet of the mother liquor of the spiral centrifuge to retain trehalose in the mother liquor and output the retentate. The outlet of the seed activation tank is connected to the inlet of the uppermost crystallization tank among the plurality of crystallization tanks via a seed delivery pump and a seed filter; the outlet of the nanofiltration membrane separator is connected to the inlet of the ion exchange resin column via a reflux pipe; the temperature of the crystallization tank decreases vertically from top to bottom.

[0048] Specifically, the detection module includes: An ultrasonic detector is installed on the outer wall of the ion exchange resin column to measure the amplitude of the ultrasonic reflected wave from the ion exchange resin column. A conductivity sensor is installed at the outlet of the collection chamber to obtain the conductivity value of the trehalose concentrate at the outlet of the collection chamber.

[0049] In one specific embodiment, there are 5 crystallization tanks, and the temperature ranges of the crystallization tanks from top to bottom are 55°C to 60°C, 50°C to 55°C, 45°C to 50°C, 40°C to 45°C, and 35°C to 40°C, respectively.

[0050] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A continuous crystallization method for producing crystalline trehalose, characterized in that, include: The pre-filtered trehalose concentrate was injected into the inlet of the ion exchange resin column to desalinate the trehalose concentrate. The amplitude of the ultrasonic reflected wave of the ion exchange resin column during the injection process of trehalose concentrate was obtained; The feed flow rate of the trehalose concentrate is determined based on the first conductivity value of the trehalose concentrate at the outlet of the collection chamber below the ion exchange resin column within the conductivity monitoring period that meets the preset amplitude conditions. The trehalose concentrate is continuously injected into the inlet of the ion exchange resin column according to the feed flow rate, and the second conductivity value of the trehalose concentrate at the outlet of the collection chamber below the ion exchange resin column is obtained during the desalination process after a preset duration. The feed flow rate of the trehalose concentrate was re-determined based on the second conductivity value; The desalination of the trehalose concentrate was completed according to the redefined feed flow rate, and the microcrystal content in the trehalose concentrate at the outlet of the collection chamber below the ion exchange resin column was obtained. The crystallization temperature of the corresponding crystallizer is determined based on the microcrystal content. The desalted trehalose concentrate was crystallized at the specified crystallization temperature, and the resulting crystal slurry was subjected to crystal slurry separation, mother liquor recovery, and drying in sequence to obtain the crystallized trehalose product.

2. The continuous crystallization method for producing crystalline trehalose according to claim 1, characterized in that, The determination of the trehalose concentrate feed flow rate based on the first conductivity value at the outlet of the collection chamber below the ion exchange resin column within a conductivity monitoring period that meets preset amplitude conditions includes: Compare the first conductivity value with a preset first conductivity value; If the first conductivity value is less than the preset first conductivity value The microcracks at the bottom of the ion exchange resin column were deemed to have negatively impacted the desalination effect, thus the feed flow rate of the trehalose concentrate was reduced. The preset amplitude condition is that the amplitude is greater than the preset amplitude within a unit amplitude monitoring period.

3. The continuous crystallization method for producing crystalline trehalose according to claim 2, characterized in that, The feed flow rate is positively correlated with the first conductivity value.

4. The continuous crystallization method for producing crystalline trehalose according to claim 3, characterized in that, The step of redetermining the feed flow rate of the trehalose concentrate based on the second conductivity value includes: The second conductivity value is compared with a preset second conductivity value; If the second conductivity value is greater than the preset second conductivity value, it is determined that the intermittent release of ions encapsulated by trehalose crystals inside the microcracks has a negative impact on the desalination stability of the resin column, and the feed flow rate of the trehalose concentrate is increased.

5. The continuous crystallization method for producing crystalline trehalose according to claim 4, characterized in that, The feed flow rate is positively correlated with the second conductivity value.

6. The continuous crystallization method for producing crystalline trehalose according to claim 5, characterized in that, The determination of the crystallization temperature of the corresponding crystallizer based on the microcrystal content includes: The microcrystal content is compared with the preset microcrystal content; If the microcrystal content is greater than the preset microcrystal content, it is determined that the impact on the uniformity of crystal size due to the shedding of trehalose microcrystals from the microcrack area of ​​the resin column does not meet the requirements, and the crystallization temperature of the corresponding crystallizer is reduced. The microcrystal content is the ratio of the volume of crystals with a diameter smaller than a preset diameter in the effluent at the outlet of the ion exchange resin column to the total volume of the effluent.

7. The continuous crystallization method for producing crystalline trehalose according to claim 6, characterized in that, The crystallization temperature is negatively correlated with the microcrystal content.

8. The continuous crystallization method for producing crystalline trehalose according to claim 7, characterized in that, The corresponding crystallizer is the one with the shortest material transport path between itself and the ion exchange resin column.

9. A continuous crystallizer for producing crystalline trehalose according to any one of claims 1 to 8, characterized in that, include: The feed pretreatment module is used to filter trehalose concentrate, including a ceramic membrane filter for preliminary filtration of trehalose concentrate to output trehalose concentrate, an ion exchange resin column connected to the ceramic membrane filter for desalination of trehalose concentrate, and a support layer disposed below the ion exchange resin column to provide support to the ion exchange resin column. A continuous crystallization module, which is connected to the feed pretreatment module, is used to continuously crystallize the desalted trehalose concentrate. It includes a concentration regulating tank connected to the liquid collection chamber outlet of the support layer for adjusting the concentration of the desalted material to be crystallized, and a crystallization separation component for continuous crystallization and post-crystallization treatment to output the crystallized trehalose product. The detection module is connected to the feed pretreatment module and the continuous crystallization module respectively, and is used to obtain the amplitude of the ultrasonic reflected wave of the ion exchange resin column, the first conductivity value of the trehalose concentrate at the outlet of the collection chamber below the ion exchange resin column within the conductivity monitoring period that meets the preset amplitude conditions, the second conductivity value of the trehalose concentrate at the outlet of the collection chamber during the desalination process after a preset duration, and the microcrystal content in the trehalose concentrate at the outlet of the collection chamber. A control module, which is connected to the detection module, the feed pretreatment module and the continuous crystallization module respectively, is used to determine the feed flow rate of trehalose concentrate based on the amplitude and the first conductivity value, redetermine the feed flow rate based on the second conductivity value, and determine the crystallization temperature of the corresponding crystallizer based on the microcrystal content.

10. The continuous crystallizer of the continuous crystallization method for producing crystalline trehalose according to claim 9, characterized in that, The crystallization separation component includes: Several crystallization tanks are arranged below the concentration regulating tank, with each crystallization tank connected in series vertically to adjacent crystallization tanks, for continuous crystallization of the material to be crystallized; A spiral centrifuge, connected to the outlet of the lowest crystallizer among several crystallizers, is used to separate the crystallized slurry to output wet crystals and mother liquor. A seed activation tank is connected to the corresponding outlet of the wet crystal of the spiral centrifuge, and is used to activate the wet crystal to output seed crystals; A nanofiltration membrane separator is connected to the corresponding outlet of the mother liquor of the spiral centrifuge to retain trehalose in the mother liquor and output the retentate. The outlet of the seed activation tank is connected to the inlet of the uppermost crystallization tank among the plurality of crystallization tanks via a seed delivery pump and a seed filter; the outlet of the nanofiltration membrane separator is connected to the inlet of the ion exchange resin column via a reflux pipe; the temperature of the crystallization tank decreases vertically from top to bottom.

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