阅读说明：本技术 一种基于涡流管和喷射器的真空冷冻干燥系统及其操控方法 (Vacuum freeze drying system based on vortex tube and ejector and control method thereof ) 是由 金圣涵 郝新月 毛鹏飞 王国成 于 2020-08-27 设计创作，主要内容包括：本发明公开了一种基于涡流管和喷射器的真空冷冻干燥系统及其操控方法,包括高压气源模块和真空冷冻干燥模块,空气作为工作介质；高压气源模块包括空气压缩机,空气压缩机出口通过管路依次连接储气罐、冷却器和干燥装置；真空冷冻干燥模块包括喷射器、涡流管、物料干燥室、冷阱和气阀。本发明根据被干燥物料及地区环境参数,调节源自高压气源模块的工作工质参数,高压空气分别进入涡流管和喷射器,经喷射器喷嘴在喷射器中形成真空腔,为物料干燥室和冷阱提供低压环境,经涡流管分离出高、低温空气,分别进入物料干燥室,以实现真空冷冻干燥环境,完成物料的一次和二次干燥,获取快速、深度干燥的效果,干燥过程节能环保无污染。(The invention discloses a vacuum freeze-drying system based on a vortex tube and an ejector and an operation method thereof, wherein the vacuum freeze-drying system comprises a high-pressure gas source module and a vacuum freeze-drying module, and air is used as a working medium; the high-pressure air source module comprises an air compressor, and an outlet of the air compressor is sequentially connected with an air storage tank, a cooler and a drying device through pipelines; the vacuum freeze drying module comprises an ejector, a vortex tube, a material drying chamber, a cold trap and an air valve. According to the invention, according to the dried material and regional environment parameters, the working medium parameters from the high-pressure air source module are adjusted, high-pressure air respectively enters the vortex tube and the ejector, a vacuum cavity is formed in the ejector through the nozzle of the ejector, a low-pressure environment is provided for the material drying chamber and the cold trap, high-temperature air and low-temperature air are separated through the vortex tube and respectively enter the material drying chamber, so that the vacuum freeze drying environment is realized, the primary drying and the secondary drying of the material are completed, the effects of rapid and deep drying are obtained, and the drying process is energy-saving, environment-friendly and pollution-free.)

1. A vacuum freeze-drying system based on a vortex tube and an ejector is characterized in that: the device comprises a high-pressure air source module and a vacuum freeze drying module, wherein air is used as a working medium;

the high-pressure air source module comprises a compressor, and an outlet of the air compressor is sequentially connected with an air storage tank, a cooler and a drying device through pipelines;

the vacuum freeze drying module comprises an ejector, a vortex tube, a material drying chamber, a cold trap, a first hot end air valve, a second hot end air valve, a first cold end air valve, a second cold end air valve, a first exhaust valve, a second exhaust valve and a condensed water discharge device; the inlet of the vortex tube and the working medium inlet of the ejector are respectively connected with the outlet of the drying device through pipelines, and the hot end outlet of the vortex tube is connected with the material drying chamber through a first hot end air valve; the outlet of the cold end of the vortex tube is connected with the material drying chamber through the first cold end air valve and connected with the cold trap through the second cold end air valve; the material drying chamber, the cold trap and the low-pressure end inlet of the ejector are connected in sequence.

2. The vortex tube and ejector based vacuum freeze-drying system of claim 1, wherein: and an output pipeline of the drying device is provided with an air purifying device.

3. The vortex tube and ejector based vacuum freeze-drying system of claim 1, wherein: the first hot end air valve is communicated with the environment through a pipeline.

4. The vortex tube and ejector based vacuum freeze-drying system of claim 1, wherein: the cold trap is connected with the inlet of the low-pressure end of the ejector through a pipeline, and a condensed water discharging device is further arranged on the cold trap.

5. The vortex tube and ejector based vacuum freeze-drying system of claim 1, wherein: and the outlet of the material drying chamber is communicated with the environment through the first exhaust valve, and the outlet of the cold trap is communicated with the environment through the second exhaust valve.

6. The vortex tube and ejector based vacuum freeze-drying system of claim 1, wherein: the outlet of the ejector is in communication with the environment via a conduit.

7. The vortex tube and ejector based vacuum freeze-drying system of claim 1, wherein: the drying means includes, but is not limited to, an adsorbent.

8. Method of operating a vortex tube and ejector based vacuum freeze-drying system according to any of claims 1 to 7, characterized in that: the method comprises the following steps:

(1) regulating and controlling state parameters of high-pressure gas from the high-pressure gas source module, and driving the ejector and the vortex tube to work so as to obtain working conditions required by material drying;

(2) the low-pressure end inlet of the ejector is connected with the cold trap through a pipeline, a vacuum environment is provided for the material drying chamber and the cold trap, and the outlet of the ejector is communicated with the environment;

(3) the hot end outlet of the air source which is subjected to cold and hot separation by the vortex tube is connected with the material drying chamber through a first hot end air valve; the cold end outlet is connected with the material drying chamber through the first cold end air valve and is respectively regulated through a first cold end air valve and a first hot end air valve;

firstly, adjusting a first cold end air valve to achieve the required vacuum freezing condition in the material drying chamber, and secondly, adjusting a second hot end air valve to achieve the purpose of sublimation drying of the material moisture;

(4) the cold trap is connected with the cold end of the vortex tube through a pipeline, a second cold end air valve is arranged on the pipeline, and meanwhile, the cold trap is communicated with the drying chamber to achieve secondary vacuum freeze drying.

Technical Field

The invention belongs to the technical field of low-temperature vacuum drying, and particularly relates to a vacuum freeze-drying system of a vortex tube and an ejector and an operation and control method thereof.

Background

With the improvement of the living standard of people in China, people have higher and higher pursuit on the health of diet, and for food, the people not only pay attention to aspects of sanitation, taste, nutritive value and the like, but also have higher requirements on the health of food.

In the past, dried fruits appear because the preservative technology is not advanced enough, the fruits need to be dried in the sun and dried to prevent the fruits from going bad, and at present, the dried fruits are eaten because the rich taste of the dried fruits is favored; traditional sun drying or baking can damage some nutritional ingredients in fruits to different degrees, sugar and vitamin loss is high, although minerals and proteins are stable, trace volatile substances are also lost, and flavor is affected; the loss of sugars increases with increasing temperature and with increasing time; in the aspect of vitamins, VC is damaged most quickly by oxidation, the factors such as oxygen content, temperature, illumination and the activity and content of ascorbic acid enzyme in the environment are influenced, VB1 is sensitive to heat, VB2 is sensitive to light, and carotene is also lost due to oxidation; furthermore, browning of different degrees can occur during the drying process or during the storage of the dried products, and the storage period depends heavily on the type of the dried products and the storage conditions such as oxygen, temperature, humidity, illumination and the like.

Therefore, in order to retain the original vitamins and saccharides in the fruit to a greater extent, the freeze-drying technology is adopted to remove the water in the fruit, and the following advantages are achieved: the nutritive value of the fruits is retained to the maximum extent, the drying period is shortened, the drying cost is saved, deep drying is realized, and the storage time of the fruits is prolonged.

According to an ejector-based vortex tube refrigeration system disclosed by Zhejiang university, the publication date is 2011, 11 and 23 days, the authorization date is 2012, 9 and 5 days, and paragraph 3 of the specification describes: the vortex tube device is characterized in that high-pressure gas can be separated into two streams of fluids with different cold and hot after flowing into a vortex tube, the temperature of the fluid flowing out of the cold end of the vortex tube can be 80 ℃ lower than that of the fluid flowing out of the inlet by controlling the opening degree of a valve, and meanwhile, the temperature of the fluid flowing out of the hot end of the vortex tube can be increased by 100 ℃ higher than that of the fluid flowing out of the inlet; the vortex tube is used for the refrigeration technology, the feasibility is realized, but the system uses the ejector to recover the refrigerant energy at the outlet of the cold end, the efficiency is low, the overall performance is influenced, and the system works in a normal pressure mode and has poor matching degree with the characteristics of the dry materials.

The patent document with the publication number of CN110207472A discloses a vacuum efficient drying device, the system uses a vortex tube group to dehumidify high-temperature air flow formed by compressed air flow and then enters a feeding cavity to take away material moisture, meanwhile, rapid evaporation of moisture in low-pressure and low-temperature environments is realized by means of wall surface heat transfer of a vortex tube, the system fully utilizes the advantages of vacuum evaporation, and the vacuum efficient drying device has the advantages of high efficiency of dried materials, low moisture content and the like, but the system adopts an electrically driven vacuum pump to create a vacuum environment, and the problem of high energy consumption exists.

The grant date is 2020, 1 month and 21 days, and utility model patent document with publication number CN209978519U discloses a fodder drying device based on vortex tube, and this system utilizes the vortex tube technique, utilizes cold, the hot air current of its separation respectively, is used for the material to dry with the hot air current, and the cold air current is used for the condensation to dehumidify, but dry material is in and goes on under the atmospheric pressure, and dehydration and dehumidification efficiency is not high, and dry dehumidification performance is influenced by air current working parameter comparatively sensitively.

Therefore, it is a problem to be solved by those skilled in the art to provide a dehumidification drying system with low energy consumption, high efficiency and adjustable operation parameters.

Disclosure of Invention

The first aspect of the invention aims to provide a vacuum freeze-drying system based on a vortex tube and an ejector, which realizes high-quality, low-cost, rapid and low-energy-consumption vacuum freeze-drying and reduces the damage to the nutrient components in the material and the microstructure thereof as much as possible.

In order to achieve the purpose, the invention adopts the following technical scheme:

a vacuum freeze-drying system based on a vortex tube and an ejector comprises a high-pressure air source module and a vacuum freeze-drying module, wherein air is used as a working medium; the parameters of the working medium are regulated and controlled according to the requirements of the dried material;

the high-pressure air source module comprises a compressor, and an outlet of the air compressor is sequentially connected with an air storage tank, a cooler and a drying device through pipelines;

the vacuum freeze drying module comprises an ejector, a vortex tube, a material drying chamber, a cold trap, a first hot end air valve, a second hot end air valve, a first cold end air valve, a second cold end air valve, a first exhaust valve, a second exhaust valve and a condensed water discharge device; the inlet of the vortex tube and the working medium inlet of the ejector are respectively connected with the outlet of the drying device through pipelines, and the hot end outlet of the vortex tube is connected with the material drying chamber through a first hot end air valve; the outlet of the cold end of the vortex tube is connected with the material drying chamber through the first cold end air valve and connected with the cold trap through the second cold end air valve; the material drying chamber, the cold trap and the low-pressure end inlet of the ejector are sequentially connected; firstly, the first cold end air valve is adjusted to achieve the vacuum freezing condition in the material drying chamber, and secondly, the second hot end air valve is adjusted to achieve the purpose that the material moisture is directly vaporized into water vapor from solid ice, so that the sublimation drying is achieved, and the primary drying is completed.

Preferably, the second hot end air valve is adjusted to provide enough adsorption heat for the dried material so as to remove the bound water in the material, complete secondary drying and achieve the purpose of deep drying.

Preferably, the air purification device is arranged on the output pipeline of the drying device, so that the cleanness degree of the air entering the material drying chamber is guaranteed to reach the edible level, and the food is prevented from being polluted to cause adverse consequences.

Preferably, the first hot end gas valve is communicated with the environment through a pipeline.

Preferably, the cold trap is connected with the inlet of the low-pressure end of the ejector through a pipeline so as to achieve the purpose of low-temperature water locking, and the cold trap is further provided with a condensed water discharging device.

Preferably, the outlet of the material drying chamber is in communication with the environment through the first exhaust valve, and the outlet of the cold trap is in communication with the environment through the second exhaust valve.

Preferably, the outlet of the ejector is in communication with the environment via a conduit.

Preferably, the drying device comprises an adsorbent, but is not limited to the adsorbent, and the material is dried and dehumidified by adopting an adsorption dehumidification mode.

A second aspect of the object of the present invention is to provide a method for operating a vortex tube and ejector based vacuum freeze drying system, comprising the steps of:

(1) regulating and controlling state parameters of high-pressure gas from the high-pressure gas source module, and driving the ejector and the vortex tube to work so as to obtain working conditions required by material drying;

(2) connecting an inlet at the low-pressure end of the ejector with the cold trap through a pipeline, providing a vacuum environment for the material drying chamber and the cold trap, and communicating an outlet of the ejector with the environment;

(3) the hot end outlet of the air source which is subjected to cold and hot separation by the vortex tube is connected with the material drying chamber through a first hot end air valve; the cold end outlet is connected with the material drying chamber through the first cold end air valve and is respectively regulated through a first cold end air valve and a first hot end air valve;

firstly, adjusting a first cold end air valve to achieve the required vacuum freezing condition in the material drying chamber, and secondly, adjusting a second hot end air valve to achieve the purpose of sublimation drying of the material moisture;

(4) the cold trap is connected with the cold end of the vortex tube through a pipeline, a second cold end air valve is arranged on the pipeline, and meanwhile, the cold trap is communicated with the drying chamber to achieve secondary vacuum freeze drying.

According to the invention, air is used as a working medium, an air compressor is used as a heat source for inputting, the air enters a vortex tube and an ejector respectively after being controlled and adjusted by proper parameters, the temperature of a material is adjusted by the vortex tube, a low-pressure environment is created by the ejector, so that moisture in the material is frozen to a temperature below the triple point pressure of the material, the moisture is directly sublimated to a gas state and is taken away, the primary drying effect is realized, and then an adsorption heat is provided for material drying by adjusting a hot end air valve of the vortex tube, so that the secondary drying effect of desorption is realized.

The invention has the beneficial effects that:

(1) the vacuum freezing module has a simple structure, does not have moving parts, has long service life, low cost and environment-friendly operation, takes the ejector and vortex tube technology as a core, adapts to the external environments of different areas under the conditions of adjustable temperature, pressure and moisture content, realizes the quick drying of the dried materials, reduces the drying cost and really realizes the energy-saving drying;

(2) the invention adopts a vacuum drying dehumidification method, so that the loss of nutrient substances can be reduced to the greatest extent while materials are dried;

(3) according to the invention, through twice low-temperature drying, the moisture of the materials is removed to the greatest extent, a better fresh-keeping effect is achieved, and the fresh-keeping time is delayed.

Drawings

FIG. 1 is a schematic diagram of a vortex tube and ejector based vacuum freeze drying system.

Reference numerals: 1. the air compressor, 2, the high-pressure air storage tank, 3, the air cooler, 4, the air dryer, 5, the ejector, 6, the vortex tube, 7, the first hot end air valve, 8, the second hot end air valve, 9, the first cold end air valve, 10, the second cold end air valve, 11, the material drying chamber, 12, the cold trap, 13, the first exhaust valve, 14, the second exhaust valve and 15, the condensed water discharge device.

Detailed Description

The present invention will be further described with reference to the following specific examples.

As shown in fig. 1, a freeze-drying system based on a vortex tube and an ejector of the present embodiment includes a high-pressure gas source module and a vacuum freeze-drying module.

Air enters an air compressor 1 through a filter, high-temperature and high-pressure air is obtained through the air compressor 1, the air enters an air cooler 3 and a drying device 4 after passing through an air storage tank 2 to obtain a high-pressure air source with proper working parameters, the high-pressure air enters an ejector 5 and a vortex tube 6 respectively in two paths, the high-pressure air is accelerated to supersonic speed through a Laval nozzle in the ejector 5, a vacuum cavity is formed at the outlet of the Laval nozzle, and a low-pressure environment is provided for a material drying chamber 11 and a cold trap 12; high-pressure air enters the vortex tube 6, high-temperature air and low-temperature air are separated out after passing through the nozzle and enter the material drying chamber 11 through the second hot end air valve 8 and the first cold end air valve 9 respectively, and the working conditions in the material drying chamber 11 are controlled and adjusted by the second hot end air valve 8 and the first cold end air valve 9; specifically, the ejector 5 provides vacuum for the drying chamber 11 and the cold trap 12, and simultaneously controls the first cold end air valve 9 to obtain a low-temperature environment to freeze free water of the material in the drying chamber 11, and then controls the second hot end air valve 8 to raise the temperature, wherein in the vacuum low-temperature environment, water is directly vaporized into water vapor from solid ice, air rich in water vapor enters the cold trap 12, liquid water is separated out in the vacuum low-temperature environment, and primary drying is completed; and then, adjusting a second hot end air valve 8 to provide desorption heat for material drying so as to remove the bound water which is tightly bound with the material, thereby finishing secondary drying. Liquid water precipitated in the cold trap 12 is discharged by the condensed water discharging device 15, and water in the drying system is thoroughly discharged; waste gas at the lower end outlet of the ejector 5, waste gas at the lower end outlet of the material drying chamber 11 and waste gas at the lower end outlet of the cold trap 12 are discharged into the environment through pipeline connection, a pipeline and a first exhaust valve 13 are arranged at the lower end outlet of the material drying chamber 11, and a pipeline and a second exhaust valve 14 are arranged at the lower end outlet of the cold trap 12; the hot end waste gas of the vortex tube 6 is discharged to the environment by a first hot end gas valve 7.

Specifically, the application of the freeze drying system to outdoor state parameters is as follows: dried waxberry with the temperature of 35.1 ℃, the humidity of 68 percent and the moisture content of 24.4 g/kg. The high-pressure air source module outputs the compressed air with the pressure of 800kPa, the temperature of 40 ℃, the humidity of 15 percent, the outlet temperature of the cold end of the vortex tube 6 of 30 ℃, the outlet temperature of the hot end of 60 ℃ and the cold flow ratio of 0.3; the inlet pressure of the low-pressure end of the ejector 5 is 0.06kPa and is lower than the pressure of a triple point; the cold end of the vortex tube 6 is cooled and frozen rapidly by the dried material, meanwhile, the ejector 5 provides vacuum cavities for the material drying chamber 11 and the cold trap 12, then the hot end of the vortex tube 6 provides heat for sublimation of the material moisture in the material drying chamber 11, the air rich in water vapor separates out liquid water in the cold trap 12, and drying and dehumidification are completed. The vacuum freeze drying technology is adopted, so that the moisture of the materials is removed to the maximum extent, and the drying and dehumidifying effects of low energy consumption, rapidness and high quality are achieved.

Taking 10kg of waxberries with the water content of 80% as an example, the total dehumidification load is 24179 kJ, compared with the traditional step heating and drying technology of a heat pump dryer, the drying cycle can be shortened from 18 hours to 2.5 hours, the drying efficiency is obviously improved, the air displacement of a compressor is 3.0L/min, the high-grade electric energy can be saved by 16.5 kW.h, and the energy-saving effect is obvious.