Dissolving and crystallizing device for stevioside production

Abstract

The utility model belongs to the technical field of chemical equipment, and discloses a dissolving and crystallizing device for stevioside production, which comprises a kettle body of a reaction kettle, a jacket for temperature control arranged on the side wall of the kettle body, a feed port and a window arranged at the top of the kettle body, a driving device arranged at the upper part of the center of the top, and a stirring shaft connected with the lower part of the driving device and extending into the kettle body, a scraper supporting arm is arranged at the upper part of the stirring shaft; scrapers are downwards arranged at the two ends of the scraper supporting arm respectively; a helical ribbon stirrer is arranged on the stirring shaft at the lower part of the scraper supporting arm; a six-straight-blade opening turbine paddle is arranged on the stirring shaft at the lower part of the helical ribbon stirrer; a push type stirring paddle is arranged at the bottom of the stirring shaft. According to the utility model, the dissolving and crystallizing processes are combined into one reaction device, and the dissolving and crystallizing efficiencies are obviously improved, so that the working efficiency is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of chemical equipment, and particularly relates to a dissolution and crystallization device for stevioside production. Background Art

[0002] Stevioside, commonly known as stevioside, is a glycoside extracted from the leaves of the Compositae plant Stevia rebaudiana. It has the characteristics of high sweetness and low calorie, and has good stability, great edible value, and has been widely used, and is known as the world's third sugar source.

[0003] The existing crystallization steps of stevioside are all dry powder crystallization (for preparing different steviosides), that is, the mother liquor sugar obtained from the previous process (the glycoside content in the mother liquor sugar is different due to different previous processes, and different glycoside contents can be crystallized separately) is dissolved and crystallized through different solvents for separation to obtain different stevioside products. In the traditional process, the dissolution and crystallization of stevioside are carried out separately, resulting in low production efficiency; and generally, paddle stirring is used for dissolution. Although paddle stirring has a good mixing and stirring effect on the materials, the dissolution efficiency of stevioside is still poor, and the material liquid is viscous after dissolution. The viscous material is easy to block the discharge port, thus affecting the dissolution efficiency of stevioside; generally, frame stirring is used for crystallization. Although the amount of stirring of the crystallization material by frame stirring is relatively large, because the material becomes sticky after stevioside crystallization, not only is the material easy to block the discharge port, but also it affects the size of the crystal form during the crystallization process. Because the stirring is not sufficient, the crystal form will be larger and the purity will be lower, seriously affecting the crystallization efficiency of stevioside. Summary of the Invention

[0004] The technical problem to be solved by the utility model is to provide a dissolution and crystallization device for stevioside production, which overcomes the defects in the prior art, combines the dissolution and crystallization processes in one reaction device, and significantly improves the dissolution and crystallization efficiencies, thereby improving the working efficiency.

[0005] To solve the above technical problem, the technical solution of the utility model is:

[0006] A dissolution and crystallization device for stevioside production includes the kettle body of a reaction kettle. A jacket for temperature control is provided on the side wall of the kettle body. An inlet and a viewing window are provided at the top of the kettle body, and a driving device is provided above the center of the top; a stirring shaft extending into the interior of the kettle body is connected to the lower part of the driving device. A scraper support arm is provided on the upper part of the stirring shaft, and scrapers are respectively provided downward at both ends of the scraper support arm; a spiral ribbon stirrer is provided on the stirring shaft below the scraper support arm, and a six-straight-blade open turbine impeller is provided on the stirring shaft below the spiral ribbon stirrer; a propeller agitator is provided at the bottom of the stirring shaft.

[0007] Preferably, a heat exchange medium inlet is provided at the bottom of the jacket, and a heat exchange medium outlet is provided at the top. The temperature control of the dissolution and crystallization processes is achieved through the flow of the heat exchange medium.

[0008] Preferably, the driving device includes a motor, a speed reducer, a transmission mechanism, and a shaft seal device.

[0009] Preferably, the outer side of the scraper is fitted to the inner side of the side wall of the kettle body. It scrapes off the sugar mass attached to the inner wall of the kettle body during the dissolution of stevioside.

[0010] Preferably, the ribbon of the ribbon-type agitator has three groups, the pitch is equal to the screw diameter (1 times the diameter), and the distance between the edge of the agitator and the inner side of the scraper is 1-2 cm. The ribbon-type agitator can make the material spiral upward along the container wall, which can prevent the material from adhering to the wall.

[0011] Preferably, the distance between the bottom of the ribbon-type agitator and the six-straight-vane open turbine impeller is 3-5 cm. The impeller size of the six-straight-vane open turbine impeller is 1 / 3 of the kettle diameter.

[0012] Preferably, the distance between the bottom of the six-straight-vane open turbine impeller and the propeller agitator is 3-5 cm.

[0013] Preferably, the propeller agitator is a three-impeller propeller agitator. Its function is to prevent the material from blocking the discharge port when discharging after crystallization. The blade diameter of the three-impeller propeller agitator is 1 / 3 of the kettle diameter, and the distance from the bottom of the kettle is 2-3 cm.

[0014] Preferably, a discharge port is provided at the bottom of the kettle body.

[0015] Due to the adoption of the above technical solutions, the beneficial effects of the present utility model are as follows:

[0016] In the present utility model, through the ribbon-type agitator, the material spirals upward along the container wall surface and then converges to the central concave cavity, forming an up-and-down convection cycle, which can prevent the material from adhering to the wall; the six-straight-vane open turbine impeller has a high shear force, which can prevent the phenomenon of wrapping impurities due to too fast crystallization during the crystallization process; the propeller agitator can prevent the material from blocking the discharge port during discharging; the scraper can scrape off the sugar mass attached to the inner wall of the kettle body.

[0017] In short, the present utility model combines the dissolution and crystallization processes in one reaction device, and the efficiency of both dissolution and crystallization is significantly improved, thereby improving the working efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic structural diagram of an embodiment of the present utility model;

[0019] Among them, 1. kettle body; 2. jacket; 3. driving device; 4. stirring shaft; 5. scraper support arm; 6. scraper; 7. spiral ribbon agitator; 8. six-straight-vane open turbine impeller; 9. propeller agitator paddle. Detailed implementation manners

[0020] The following further elaborates on the present utility model in conjunction with the accompanying drawings and embodiments.

[0021] As Figure 1 shown, a dissolution and crystallization device for stevioside production includes the kettle body 1 of a reaction kettle. A jacket 2 for temperature control is provided on the side wall of the kettle body 1. A feed inlet (not marked) and a viewing window (not marked) are provided at the top of the kettle body 1, and a driving device 3 is provided above the center of the top; the lower part of the driving device 3 is connected to a stirring shaft 4 extending into the interior of the kettle body 1. A scraper support arm 5 is provided on the upper part of the stirring shaft 4, and scrapers 6 are respectively provided downward at both ends of the scraper support arm 5; a spiral ribbon agitator 7 is provided on the stirring shaft 4 below the scraper support arm 5, and a six-straight-vane open turbine impeller 8 is provided on the stirring shaft 4 below the spiral ribbon agitator 7; a propeller agitator paddle 9 is provided at the bottom of the stirring shaft 4.

[0022] In actual application, first turn on the stirring and heat exchange devices, and then input the concentrated liquid from the previous process and the dissolving water into the reaction kettle through the feed inlet in proportion. Stir and dissolve for 15 - 30 minutes under the conditions of a temperature of 50 - 90 °C and a rotation speed of 120 - 145 revolutions per minute. Then adjust the flow rate of the heat exchange medium to 0.5 - 3 m / s through the heat exchange device, adjust the temperature of the material in the reaction kettle to decrease by 5 - 10 °C to 30 °C in sequence, adjust the rotation speed to 60 - 120 revolutions, and start crystallization. After 2 hours of crystallization, transfer the material to a centrifuge in the subsequent process through the discharge port provided at the bottom of the reaction kettle for centrifugal separation, and perform the operations of the subsequent process in sequence; the process of recrystallization can also be carried out in the present utility model, and the production process is the same as the foregoing.

[0023] Among them, the temperature and flow rate of the heat exchange medium are determined according to the material (there are various glycosides of stevioside, and different glycosides use different parameters). For some glycosides, crystallization does not require a rapid change in temperature, for some glycosides, specific temperatures are required, and the flow rate will also change. The flow rate will become faster for those that require rapid cooling; the dissolving temperature is also set according to the requirements of the next crystallization. Therefore, the above parameters can only be fixed according to the preparation of a certain glycoside.

[0024] It should be understood that these embodiments are only used to illustrate the present utility model and not to limit the scope of the present utility model. In addition, it should be understood that after reading the content taught by the present utility model, those skilled in the art can make various changes or modifications to the present utility model, and these equivalent forms also fall within the scope defined by the appended claims of this application.

Claims

1. A dissolving and crystallizing device for stevioside production, characterized in that: The invention comprises a kettle body of a reaction kettle, wherein the side wall of the kettle body is provided with a jacket for temperature control, the top of the kettle body is provided with a feed port and a viewing window, and the upper center part of the top is provided with a driving device; the lower part of the driving device is connected with a stirring shaft extending into the kettle body, the upper part of the stirring shaft is provided with a scraper support arm, and the two ends of the scraper support arm are respectively provided with scrapers downward; a screw-belt agitator is provided on the stirring shaft at the lower part of the scraper support arm, and a six-straight-blade open turbine impeller is provided on the stirring shaft at the lower part of the screw-belt agitator; a propulsion stirring paddle is provided at the bottom of the stirring shaft.

2. The dissolving and crystallizing device for stevioside production according to claim 1, characterized in that: The bottom of the jacket is provided with a heat exchange medium inlet, and the top is provided with a heat exchange medium outlet.

3. The dissolving and crystallizing device for stevioside production according to claim 1, characterized in that: The driving device comprises a motor, a reducer, a transmission mechanism and a shaft sealing device.

4. The dissolving and crystallizing device for stevioside production according to claim 1, characterized in that: The outer side of the scraper is in contact with the inner side of the side wall of the kettle body.

5. The dissolving and crystallizing device for stevioside production according to claim 1, characterized in that: The ribbon agitator has three groups of ribbons.

6. The dissolving and crystallizing device for stevioside production according to claim 1, characterized in that: The propulsion stirring paddle is a three-impeller propulsion stirring paddle.

7. The dissolving and crystallizing device for stevioside production according to claim 1, characterized in that: A discharge port is arranged at the bottom of the kettle body.

Images