CN112240682A

CN112240682A - Spray freeze drying device for continuous production

Info

Publication number: CN112240682A
Application number: CN202011101912.XA
Authority: CN
Inventors: 刘志强; 罗春; 米沙; 张泽宗
Original assignee: Central South University
Current assignee: Central South University
Priority date: 2020-10-14
Filing date: 2020-10-14
Publication date: 2021-01-19

Abstract

The invention belongs to the field of spray freeze-drying and aims to solve the problem that the existing spray freeze-drying device takes a long time. The device is mainly composed of a freezing chamber, a drying chamber and a discharging device. Its main features are: the freezing chamber, the drying chamber and the discharging device are directly connected, the precursor solution forms several small droplets through the nozzle, and the droplets fall under the action of gravity. The drying process, and then through the discharge device, are collected together. The device realizes the integration of freezing process, drying process and discharging process, saves time, improves efficiency, and avoids pollution caused by human operation.

Description

Spray freeze drying device for continuous production

Technical Field

The invention relates to a spray freeze drying device, in particular to a novel spray freeze drying device for continuous production, and belongs to the field of spray freeze drying.

Background

The spray freeze drying technology is a new technology and mainly comprises three sub-processes: atomizing, freezing and drying. The prepared precursor solution is firstly atomized into very small droplets through a nozzle, and then is in contact heat exchange with a cooling medium (liquid nitrogen, low-temperature gas and the like), the small droplets are frozen in a short time due to the very high heat transfer rate in a low-temperature environment, and then the frozen droplets are dried in a vacuum environment to obtain a final product.

The medicine powder prepared by the spray freeze drying technology has the advantages of less agglomeration, uniform size, good biological activity and the like. Therefore, the spray freeze drying technology is widely applied to the field of medicine preparation. However, the mass production mode is generally adopted in the current production, which brings about two problems, on one hand, the whole process takes a long time because of the need of continuous feeding and material changing. On the other hand, human handling can negatively affect the sterility of the product. Therefore, the continuous production device is very important for improving the efficiency and the sterility of the process.

There are also some patents relating to spray freeze drying devices, such as the one proposed in patent US9945611B2, which have an agitator used to avoid agglomeration between particles. The apparatus is still batch-wise produced. An integrated spray freeze-drying apparatus and method is also reported in patent CN101441030A, but this method still does not completely realize continuous production, and the prepared product still needs to be taken out after the whole process is finished. And the introduced stirrer increases the energy consumption of the whole system.

It can be seen from the above-mentioned published documents that there is no report on a continuous production device for spray freeze drying at present, and the invention adopts a new idea to design a spray freeze drying device capable of continuous production, which can effectively improve the efficiency of the spray freeze drying process.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a spray freeze drying device which can realize continuous production in practice, improve the spray freeze drying efficiency and reduce the pollution caused by manual operation.

The technical scheme for solving the problems is as follows:

a continuously producing spray freeze-drying apparatus comprising: freezing chamber, drying chamber, discharging device. The freezing chamber, the drying chamber and the discharging device are directly connected, and liquid drops are sprayed out through the nozzles, then are respectively subjected to freezing and drying processes, and finally directly fall into the collecting device without other links.

The cold energy required by freezing the small liquid drops in the freezing chamber mainly has two sources, one is the radiation heat exchange between the small liquid drops and the wall surface, and the other is the heat exchange between the small liquid drops and liquid nitrogen.

The heat required by the droplets in the drying chamber is mainly from the radiant heat exchange of the walls.

By arranging two buffer chambers, particles fall into different buffer chambers at different times, so that the interference of the external environment on the internal vacuum degree of the device is reduced.

A condenser is provided on the wall surface of the freezing chamber, and a condenser is provided on the wall surface of the drying chamber. The wall temperature of the freezing chamber is reduced, and the wall temperature of the drying chamber is increased.

Drawings

FIG. 1 is a schematic view of an apparatus

In the figure: 1. the system comprises a precursor solution, 2 parts of a nozzle 1, 3 parts of a nozzle 2, 4 parts of a vacuum pump, 5 parts of an evaporator, 6 parts of a compressor, 7 parts of a drying chamber, 8 parts of a throttle valve, 9 parts of a condenser, 10 parts of a three-way valve, 11 parts of a valve 1, 12 parts of a buffer chamber 1, 13 parts of a

valve

2, 14 parts of a material collector, 15 parts of a

valve

3, 16 part of a

buffer chamber

2, 17 parts of a valve 4, 18 parts of a delay dropping device, 19 parts of a throttle valve, 20 parts of a compressor, 21 parts of a nitrogen tank and 22 parts of a freezing chamber.

Detailed Description

The invention is further explained by the following combined with the drawings and the embodiment.

Referring to fig. 1, the precursor solution is atomized in the nozzle 3 into a number of droplets, which fall in the freezing chamber 22. Heat exchange with the wall surface occurs during the falling, while liquid nitrogen is ejected upward at the bottom of the freezing chamber 22 via the nozzle 2, contacting the liquid droplets, so that the temperature of the liquid droplets falls and freezes. The frozen droplets enter the drying chamber 7 and the frozen particles fall onto the delayed falling device 18 while exchanging heat with the wall surface. The ice crystals in the particles are removed by sublimation. The dried particles are passed to three valves 10, where the valve 11 is opened and the particles are passed to a buffer chamber 12, after a certain time interval the valve 11 is closed and the valve 13 is opened, so that the particles are passed from the buffer chamber 12 to a material collector 14, while the valve 17 is opened and the particles are passed to a buffer chamber 16 on the other side. After the buffer chamber 16 is filled, the valve 17 is closed and the valve 15 is opened, so that the material in the buffer chamber 16 enters the material collector 14, and the valve 11 is opened again. The above steps are repeated in a circulating way, and the influence of the external environment on the internal vacuum degree of the device is reduced through the switching of the two buffer chambers.

Referring to fig. 1, the working fluid flows through the evaporator 5 on the wall of the freezing chamber 22, and is evaporated and cooled, so that the temperature of the wall of the freezing chamber is reduced. Then the working medium flows through the compressor 6 and is condensed on the wall surface of the drying chamber 7, so that the temperature of the wall surface is increased.

Claims

1. A spray freeze drying device that can be used to continuous production characterized by: the freezing chamber 3, the drying chamber 7 and the discharging device 14 are directly connected.

2. A freezing chamber as claimed in claim 1, wherein: liquid nitrogen is sprayed upwards from the bottom of the freezing chamber through the injection pump 21, the liquid nitrogen is vaporized and absorbs heat for refrigeration in the spraying process, meanwhile, the temperature of the wall surface is low, and radiation heat exchange exists between the liquid nitrogen and liquid drops, so that the liquid drops are frozen.

3. The drying chamber of claim 1, wherein: the frozen droplets fall down on the delay drying device 19, prolonging the drying time. Meanwhile, the temperature of the wall surface is high, and radiation heat exchange exists between the wall surface and the frozen particles, so that the particles are dried in a vacuum environment.

4. The time-lapse drying apparatus of claim 3, wherein: different metal plates are fixed on the same metal rod, and the residence time of the frozen particles in the drying chamber can be adjusted by setting the inclination angle of the metal plates.

5. The discharge device of claim 1, wherein: through controlling the valve, the frozen particles fall into different buffer chambers at different times, and the influence of the external environment on the internal vacuum degree of the device is reduced.

6. The freezing and drying chamber of claim 1, wherein: the same system is adopted for controlling the wall temperature of the two, the working medium is evaporated in the evaporator 5, so that the wall temperature of the drying chamber 3 is reduced, and then the working medium is condensed in the condenser 9 by the compressor 6 to release heat, so that the wall temperature of the drying chamber is increased.