Continuous microwave freeze-drying device

Abstract

A continuous microwave freeze-drying device comprises a vacuum water-trapping system (1), a microwave shield plate (2), a microwave bin (6) and a freeze-drying bin (5) located in the microwave bin (6), wherein the freeze-drying bin (5) comprises an upper bin opening, a left bin wall, a right bin wall and a bottom bin wall, and the left, right and bottom bin walls are all made from nonmetal wave transmitting materials, such as polyfluortetraethylene, polyethylene, polypropylene or quartz glass. The device solves the technical problem of freeze-drying failure caused by glow discharge of microwave under freeze-drying environment.

Claims

1. A continuous microwave freeze-drying device, comprising: a freeze-drying bin, a microwave shield plate, a vacuum water-trapping chamber, a microwave bin, and a material conveying belt, wherein the freeze-drying bin resides inside the microwave bin and is separated from the vacuum water-trapping chamber by the microwave shield plate, wherein the freeze-drying bin comprises a left bin wall, a right bin wall and a bottom bin wall, and the left, right and bottom bin walls are made from nonmetal and gas-impermeable microwave transmitting materials, wherein the microwave shield plate is a metal plate having a plurality of ventilation holes, wherein the ventilation holes allow water vapor to transfer from the freeze-drying bin to the vacuum-water trapping chamber, and wherein the material conveying belt passes through the freeze-drying bin, wherein an internal space volume of the freeze-drying bin accounts for 30%-65% of an external volume of the freeze-drying bin.

2. The continuous microwave freeze-drying device of claim 1, wherein the microwave shield plate serves as a bin wall of the microwave bin and suppresses transmittance of microwave to the vacuum-water trapping chamber.

3. The continuous microwave freeze-drying device of claim 2, wherein the microwave shield plate serves as a bin wall for the freeze-drying bin.

4. The continuous microwave freeze-drying device of claim 1, wherein the microwave transmitting materials are chosen from polyfluortetraethylene, polyethylene, polypropylene or quartz glass.

5. The continuous microwave freeze-drying device of claim 1, wherein the freeze drying bin is concave in shape and has an opening on top of the freeze drying bin.

6. The continuous microwave freeze-drying device of claim 1, characterized in that a volume of a material subject to freezing-drying inside the freeze-drying bin accounts for 35%-90% of the internal space volume of the freeze-drying bin.

7. The continuous microwave freeze-drying device of claim 1, wherein the material conveying belt is a PTFE glass fiber conveying belt.

8. The continuous microwave freeze-drying device of claim 7, wherein the PTFE glass fiber conveying belt is a mesh belt, a nonporous flat belt, or a porous flat belt.

9. The continuous microwave freeze-drying device of claim 1, further comprising a continuous vacuum feed mechanism and a continuous vacuum discharge mechanism.

Description

DESCRIPTION OF FIGURES

(1) The invention will be further described in combination with figures and preferred embodiments, and it is to be understood that the invention is not restricted thereto in any way.

(2) FIG. 1 is a horizontal sectional view of the device of the invention; and

(3) FIG. 2 is a longitudinal sectional view of the device of the invention.

(4) In the figures: 1. vacuum water-trapping system, 2. microwave shield plate, 3. material, 4. material conveying system, 5, freeze-drying bin, 6. microwave bin, 7. microwave system, 8. microwave suppressor, 9. continuous feed system, 10. continuous discharge system.

DETAILED DESCRIPTION

(5) Embodiment 1

(6) As the simplest embodiment of the invention, the left, right and bottom bin walls of the freeze-drying bin are all made from nonmetal wave transmitting materials such as polyfluortetraethylene, polyethylene, polypropylene or quartz glass based on existing continuous microwave freeze-drying devices such as two existing freeze-drying devices listed in the Background.

(7) Embodiment 2

(8) As a preferred embodiment of the invention, the continuous microwave freeze-drying device is composed of a continuous vacuum feed mechanism 9, a continuous vacuum discharge mechanism 10, a microwave system 7, a microwave suppressor 8, a vacuum water-trapping system 1, a microwave bin 6, a material conveying system 4, a freeze-drying bin 5 and a microwave shield plate 2 as shown in FIG. 1 and FIG. 2.

(9) The freeze-drying bin 5 is made from non-toxic and odor-free nonmetal microwave transmitting materials (e.g. polyfluortetraethylene) with certain strength, wave transmittance, low microwave loss and certain temperature resistance;

(10) The microwave shield plate 2 is made from metals, and provided with uniform through holes to suppress transmittance of microwave and ensure vapor permeation;

(11) The section of the freeze-drying bin 5 takes a concave shape, is provided with the microwave shield plate 2 and connected with the vacuum water-trapping system 1;

(12) The freeze-drying bin 5 is installed in the microwave bin 6 and connected by the microwave shield plate 2, i.e., the microwave shield plate 2 forms a bin wall oft he microwave bin 6;

(13) A microwave feed inlet of the microwave system 7 is installed on a bin wall of the microwave bin 6, namely, a bin wall without the microwave shield plate 2;

(14) The material conveying system 4 uses continuous circulating conveying belts (e.g. PTFE glass fiber conveying belt) made from non-toxic and odor-free materials with low microwave loss;

(15) The feed belt of the material conveying system 4 is installed in a concave groove of the freeze-drying bin 5, the return belt does not return through the freeze-drying bin 5 and returns from the exterior;

(16) The continuous vacuum feed system and the continuous vacuum discharge system have vacuum protection characteristic, and can continuously feed/discharge materials in/out of the vacuum freeze-drying bin without destroying the vacuum environment; and

(17) The microwave suppressor 8 is of a matrix pin suppressor capable of suppressing microwave leakage and material permeation.

(18) Embodiment 3

(19) Continuous microwave freeze-drying device as shown in FIG. 1 and FIG. 2

(20) The microwave system uses microwave sources with frequency of 2450 MHz by slot antenna feeding, the power of wave sources for a single device is 2 kW, and the total power of multiple devices reaches 30 kW, the freeze-drying bin 5 is made from polyfluortetraethylene, the conveying belt of the material conveying system 4 is of a PTFE coated glass fiber belt, and material 3 is a material of which 65% moisture content has been frozen below an eutectic point.

(21) Main operational processes are as follows:

(22) The vacuum water-trapping system 1 extracts vacuum to drop pressure of the freeze-drying bin 5 below 133 Pa;

(23) The material 3 is continuously sent to the conveying belt of the material conveying system 4 by the continuous feed system 9 and the microwave suppressor 8;

(24) The material system 4 continuously feeds the material 3 in the freeze-drying bin 5;

(25) The microwave system 7 feeds microwave in the microwave bin 6, and then the microwave transmits bin walls of the freeze-drying bin 5 to provide heat for the material 3 for sublimation;

(26) Vapor from moisture sublimation of the material 3 enters the vacuum water-trapping system 1 through the through holes on a microwave suppression plate 2, thus ensuring vacuum pressure for freeze-drying not to rise; and

(27) The dry material 3 is continuously discharged out of the freeze-drying bin 5 by the conveying belt of the material conveying system 4, and continuously discharged out of the device by the microwave suppressor 8 and the continuous discharge system 10 to obtain a freeze-dried material.