A menthol fractional crystallization purifier

Abstract

The present invention discloses a stepwise crystallization purifier for menthol, which is composed of a crystallization box body, a crystallization plate group and other components. A number of pipe orifices such as a feed inlet are distributed on the crystallization box body, the bottom of the box body is welded to a base, and there are a number of legs under the base. The crystallization plate group is composed of a crystallization plate, a seed plate, a medium main pipe, etc. The menthol mother liquor enters the crystallization box body through the feed inlet until it submerges the crystallization plate and flows out from the overflow outlet. The cooling medium and the heating medium enter the crystallization plate step by step from the medium inlet through the medium main pipe, exchange heat with the menthol, and then flow out from the medium outlet. Another path of cold water enters the seed plate from the cold water inlet and flows out from the cold water outlet to generate seeds outside the plate. By switching the cooling and heating media, the processes of crystallization, sweating, melting, etc. of menthol are completed step by step to achieve the purification of menthol. The beneficial effects of the present invention are that the crystallization temperature control field is more uniform, the special design of the seed plate makes the crystallization efficiency higher, the product purity is higher, and it is more energy-saving.

Description

Technical Field

[0001] The present invention relates to the field of separation and purification of menthol, and particularly to a stepwise crystallization purifier for menthol. Background Art

[0002] Menthol, scientifically named methyl isopropyl cyclohexanol and commonly known as menthol crystal. There are three chiral centers in the menthol molecule, and there are eight isomers. Among them, d,l-menthol has a cooling effect, while other isomers have no cooling effect. Due to its strong cooling effect, l-menthol in d,l-menthol has been widely used in the fields of medicine and health, essence and fragrance, food industry and daily fine chemicals. In the field of medicine and health, it can be used as an analgesic, a local anesthetic, a cooling agent, an antipruritic agent, a gargle, a bactericide, etc.; in essence and fragrance, it can be used as a tobacco flavor, and is used to prepare toothpaste essence with mint oil and prepare eau de toilette with other flavors; in the food industry, it can be used as a flavoring agent for a variety of foods, such as for preparing candies, chewing gums, pastries, fruit wines, cooling beverages, etc.; in daily necessities, l-menthol can be used as an additive component of cosmetics, such as high-grade perfumes, shampoos, soaps and other toiletries, and can also be used as an aromatic agent in household cleaners and detergents.

[0003] The common ways to obtain menthol are natural extraction and chemical synthesis. The natural extraction method has long been the main way to obtain menthol. However, due to the increasing demand and the decreasing natural resources, the chemical synthesis method has gradually attracted people's attention. The menthol obtained by chemical synthesis is usually a mixture of various isomers, and it must be purified to obtain d,l-menthol, and then l-menthol is obtained through chiral resolution.

[0004] Currently, the common menthol purification methods include distillation, crystallization, etc. It is often difficult to obtain a product with very high purity by simple distillation, and it is often used in combination with crystallization. The energy consumption of distillation is very large. The traditional crystallization method uses a shell-and-tube crystallizer. Due to its own structural characteristics, the temperature at each point inside the shell-and-tube crystallizer is often not very uniform, and this is very important for the product purity. Therefore, it is very difficult to achieve a very high product purity, and the efficiency is also relatively low. Summary of the Invention

[0005] The purpose of the present invention is to provide a stepwise crystallization purifier for menthol to solve the problems raised in the above background art.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A menthol fractional crystallization purifier includes a crystallization box body, a crystallization plate group and other components. The crystallization box body is provided with pipe orifices such as a feed port, a liquid discharge port, a medium inlet, a medium outlet, an exhaust port, a spare port, an overflow port, an upper thermometer port, a lower thermometer port, a cold water inlet, and a cold water outlet. The bottom of the crystallization box body is welded to a base, and several legs are distributed under the base. The crystallization plate group is composed of crystallization plates, seed plates, a medium main pipe, etc. The crystallization plates and the seed plates are fixed to the inner wall of the crystallization box body through plate clips. The crystallization plate group is placed on the sieve plate ridges of a sieve plate, and the sieve plate is supported by support pieces fixed to the bottom of the box.

[0008] The distance between the crystallization plates in the crystallization plate group is between 30 and 55 mm.

[0009] The crystallization plates are provided with crystallization plate branch pipes, which are the inlets and outlets of the medium in the crystallization plates. Both the crystallization plates and the seed plates are formed by laser welding two stainless steel plates, and drainage lines and shunt points are laser welded on them.

[0010] Plate clips are welded to the inner wall of the crystallization box body, and the crystallization plates and the seed plates of the crystallization plate group are inserted between the plate clips for fixation to prevent the plate group from shaking.

[0011] The center line of the bottom of the box is concave downward, forming an angle in the range of 1 to 10° with the horizontal plane.

[0012] Several support pieces are distributed on the bottom of the box, and a sieve plate is placed on the support pieces. The thickness of the sieve plate is between 5 and 10 mm.

[0013] Both sides of the sieve plate protrude to form sieve plate ridges, which support the upper crystallization plate group. Several sieve holes are distributed on the sieve plate, and the aperture of the sieve holes is between 2 and 10 mm.

[0014] The seed plate is a separately provided seed generation device. The seed plate has a separate cold water inlet and a cold water outlet, and cold water at a lower temperature is introduced, which can more easily form seeds on the outer surface of the seed plate, thereby promoting the crystallization process.

[0015] Compared with the existing menthol separation and purification equipment, the beneficial effects of the present invention are as follows:

[0016] 1. The crystallization temperature control field is more uniform.

[0017] 2. The crystallization efficiency is higher.

[0018] 3. The product purity is higher.

[0019] 4. The energy consumption is lower. Description of the Drawings

[0020] Figure 1 It is the front view of the present invention;

[0021] Figure 2 It is a side view of the crystallizer;

[0022] Figure 3 It is a top view of the crystallizer;

[0023] Figure 4 It is an external view of the crystallization plate;

[0024] Figure 5 It is an external view of the seed plate;

[0025] Figure 6 It is an external view of the sieve plate.

[0026] Reference numerals in the figure: 1, feed inlet; 2, drain outlet; 3, medium inlet; 4, medium outlet; 5, exhaust port; 6, spare port; 7, overflow port; 8, upper thermometer port; 9, lower thermometer port; 10, cold water inlet; 11, cold water outlet; 12, bottom of the tank; 13, base; 14, support leg; 15, support piece; 16, sieve plate; 17, sieve plate ridge; 18, plate clamp; 19, crystallization plate; 20, seed plate; 21, crystallization plate branch pipe; 22, medium main pipe; 23, crystallization plate group; 24, crystallization box body; 25, drainage line; 26, shunt point; 27, sieve hole. Specific embodiments

[0027] To more clearly illustrate the technology of the present invention, it will be described below with reference to the accompanying drawings.

[0028] See Figure 1-6 , a menthol fractional crystallization purifier of the present invention includes a crystallization box body 24, a crystallization plate group 23 and other components, and is characterized in that: the crystallization box body 24 is provided with pipe orifices such as a feed inlet 1, a drain outlet 2, a medium inlet 3, a medium outlet 4, an exhaust port 5, a spare port 6, an overflow port 7, an upper thermometer port 8, a lower thermometer port 9, a cold water inlet 10, and a cold water outlet 11. The bottom 12 of the crystallization box body 24 is welded to the base 13, and a number of support legs 14 are distributed under the base 13. The crystallization plate group 23 is composed of a crystallization plate 19, a seed plate 20, a medium main pipe 22, etc. The crystallization plate 19 and the seed plate 20 are fixed on the inner wall of the crystallization box body 24 through a plate clamp 18, and the crystallization plate group 23 is placed on the sieve plate ridge 17 of the sieve plate 16, and the sieve plate 16 is supported by a support piece 15 fixed to the bottom 12 of the tank.

[0029] The plate spacing of the crystallization plate 19 is between 30 - 55 mm.

[0030] The crystallization plate 19 is provided with crystallization plate branch pipes 21, which are the inlets and outlets of the medium in the crystallization plate 19. Both the crystallization plate 19 and the seed plate 20 are made of two stainless steel plates processed by laser welding, and drainage lines 25 and shunt points 26 are laser welded on them.

[0031] A circuit board 18 is welded to the inner wall of the crystallization box body 24. The crystallization plates 19 and the seed plates 20 of the crystallization plate group 23 are inserted between the circuit boards 18 and fixed to prevent the plate group from shaking.

[0032] The center line of the bottom of the box 12 is concave downward, forming an angle in the range of 1-10° with the horizontal plane.

[0033] A number of support pieces 15 are distributed on the bottom of the box 12. A sieve plate 16 is placed on the support pieces 15. The thickness of the sieve plate 16 is between 5-10 mm. The sieve plate 16 can prevent the crystallization from collapsing during the sweating process and discharging from the liquid discharge port 2, resulting in product loss.

[0034] Both sides of the sieve plate 16 bulge to form sieve plate ridges 17. The sieve plate ridges 17 support the upper crystallization plate group 23. A number of sieve holes 27 are distributed on the sieve plate 16. The aperture of the sieve holes 27 is between 2-10 mm.

[0035] The seed plate 20 is a separately provided seed generation device. The seed plate 20 has a separate cold water inlet 10 and a cold water outlet 11. Cold water at a lower temperature is introduced, and it is easier to form seeds on the outer surface of the seed plate 20, thereby promoting the crystallization process.

[0036] The menthol mother liquor enters the inside of the crystallization box body 24 through the feed port 1 until it submerges the upper edge of the crystallization plate 19, and flows out from the overflow port 7. The cooling medium and the heating medium are separately introduced into the medium main pipe 22 from the medium inlet 3, enter the inside of the crystallization plate 19, exchange heat with the menthol in the crystallization box body 24, and then flow out from the medium outlet 4. Another path of cold water enters the seed plate 20 from the cold water inlet 10 and flows out from the cold water outlet 11. Due to the lower temperature of the cold water, seeds will be generated outside the seed plate 20. Through the cooperation of the crystallization plate 19 and the seed plate 20, the processes of crystallization, sweating, and melting of menthol are completed step by step, and finally the purification of menthol is realized.

Claims

1. A menthol fractional crystallization purifier, comprising a crystallization box body (24), a crystallization plate group (23) and other components, characterized in that: The crystallization box body (24) is provided with a feed inlet (1), a liquid discharge port (2), a medium inlet (3), a medium outlet (4), an exhaust port (5), a spare port (6), an overflow port (7), an upper thermometer port (8), a lower thermometer port (9), a cold water inlet (10), and a cold water outlet (11). The bottom (12) of the crystallization box body (24) is welded to the base (13). A number of legs (14) are distributed under the base (13). The crystallization plate group (23) is composed of a crystallization plate (19), a seed plate (20), and a medium main pipe (22). The crystallization plate (19) and the seed plate (20) are fixed to the inner wall of the crystallization box body (24) by plate clips (18). The crystallization plate group (23) is placed on the sieve plate ridges (17) of the sieve plate (16), and the sieve plate (16) is supported by support pieces (15) fixed to the bottom (12). The crystallization plate (19) is provided with crystallization plate branch pipes (21), which are the inlets and outlets of the medium in the crystallization plate (19). Both the crystallization plate (19) and the seed plate (20) are made of two stainless steel plates processed by laser welding, and diversion lines (25) and diversion points (26) are laser welded on them. Both sides of the sieve plate (16) are convex to form sieve plate ridges (17). The sieve plate ridges (17) support the upper crystallization plate group (23). A number of sieve holes (27) are distributed on the sieve plate (16), and the aperture of the sieve holes (27) is 2 - 10 mm. The seed plate (20) is a separately provided seed generation device. The seed plate (20) has a separate cold water inlet (10) and a cold water outlet (11). Cold water at a lower temperature is introduced, and it is easier to form seeds on the outer surface of the seed plate (20), thereby promoting the crystallization process.

2. The stepwise crystallization purifier for menthol according to claim 1, wherein: The plate spacing of the crystallization plates (19) in the crystallization plate group (23) is between 30 - 55 mm.

3. The menthol stepwise crystallization purifier according to claim 1, wherein: Plate clips (18) are welded to the inner wall of the crystallization box body (24). The crystallization plates (19) and the seed plates (20) of the crystallization plate group (23) are inserted between the plate clips (18) for fixation to prevent the plate group from shaking.

4. A menthol fractional crystallization purifier according to claim 1, characterized in that: The center line of the bottom (12) is concave downward, forming an angle in the range of 1 - 10° with the horizontal plane.

5. A menthol fractional crystallization purifier according to claim 1, characterized in that: A number of support pieces (15) are distributed on the bottom (12). The sieve plate (16) is placed on the support pieces (15), and the thickness of the sieve plate (16) is between 5 - 10 mm.

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