Under ordinary conditions, its value is very small, sublimation of water molecules collide with the gases very easily returned to the steam source, is the sublimation rate is diffuse.
In order to link to sublimation and condensation temperature difference, it is necessary to supply enough heat to products.
Ice at the temperature of saturated steam pressure part for 63.
3 pa with 1.
1 pa, is between sublimation and condensation surface has produced a considerable pressure difference, if the system within the non-condensable gas partial pressure can not underestimate, it will lead to products to sublimation of water vapor, to reach your photocoagulator must flow directional profile form frost.
Are dry porous sponge dry matter, root volume constant, easily soluble in water and restore reply reply.
gas molecules in the continuation of the collision between two go by interval known as the uniform free path, it is inversely proportional to the pressure.
freeze drying machine system by the refrigeration system, vacuum system, heating system, electrical instrumentation control system.
Vacuum system for low pressure conditions for establishment of sublimation drying storehouse, heating system to the material supply latent heat of sublimation, refrigeration system to the cold trap and cold quantity required by the supply of drying chamber.
In the largest extent, prevent the degeneration of the physical and chemical and biological aspects of dry substance.
This method's shortcomings shortcomings is products into the box, the water vapor in the air will be adjustable solidification on the shelf, and at the beginning of the sublimation, warming faster, if the board due to a large area of sublimation is likely to be exceeded photocoagulator normal load.
This phenomenon is the summer out of line.
To get high quality products, the theory and process of freeze should have a bucket strength comprehensive body odor.
material before the dry at low temperature (always
Frozen)
, even distribution of ice crystals in the material at the same time, the sublimation process will not generate enrichment phenomenon by dehydration, prevent the vice impregnation is produced by water vapor bubble, oxidation, etc.
Its work items that things will be dry freeze below the triple point temperature first, then under vacuum conditions in the items of solid water (
Ice)
Direct sublimated into water vapor, alleviation from items, dry goods.
1 g of water vapour in the atmosphere of 1.
25 l in 13.
3 pa but inflation is 10000 litres, popular vacuum pump pumping so much quantity in unit time is can not volume.
Was admitted to the frozen warehouse material after freedom before freezing, again into the sublimation dehydration drying storehouse, back in the freedom of packaging workshop.
seller products frozen frozen (
solution
Every minute cool 10 ~ 50 ℃)
, grain links in microscopic intrusive;
On the contrary when slow freezing (
1 ℃ / min)
To form the crystallization of visible to the naked eye.
to request is: the quality of freeze-dried products outside the biological activity remains the same, even, to visit China form full, stable structure, melting speed, low residual moisture.
drugs in the lyophilizer precool in two kinds of formulation: is a kind of products and drying oven temperature, at the same time;
Additionally one kind is to be cooled to - drying oven shelf
At the mercy of 40 ℃, and then put products into, the former is equivalent to slow frozen, the latter between frozen and slow frozen, is often adopted, with both efficiency and product quality freeze-dried.
But doesn't solute crystallization, in order to overcome the supercooling phenomenon, products of frozen temperature should be a size below the eutectic point, and links for a period of time, complete freeze for products.
。
vacuum pump in the lyophilizer plays a pumping gas impregnation, forever thou to sublimation of low pressure.
Coagulator reality is made up of a special capture vapor vacuum pump.
This equipment adopts high efficient radiation heating, the material is heated evenly;
Adopt high-efficiency water well, and can realize the rapidness frost;
By high vacuum unit, and can realize part of oil and water;
The refrigeration system in parallel, multi-channel on-demand cooling, working condition of the same, good energy saving;
Using artificial intelligence control, high control precision, convenient take over.
Coarse grain in the sublimation leave a large space, can advance the efficiency of the freeze-dried, the gap left by fine grain after sublimation is lesser, make lower sublimation suffocate, quick frozen products grain of greasy, carefully look even, than the general situation of the large, porous structure, melting speed, and products of wet sex is relatively better also.
products and solidification temperature is formed
25 ℃ to -
50℃。
Land for justice and have shorten the lyophilization cycle property exist in the production of the economic value.
in lien sublimation
ice conditions and speed must be under the temperature of saturated vapor pressure is greater than the scene image image image image image of water vapor partial pressure can be preliminary sublimation;
Temperature is lower than the products of cascade suction of water vapor and capture impregnation, is the person of the necessary conditions.
Freeze-drying is dominating the sublimation things to dry a craft, is that the matter will be dry at low temperature quick frozen, and then in the appropriate vacuum image image image image image image, made of frozen water molecules directly sublimate into the process of water vapour to escape.
Freeze drying to obtain the product called lyophilization (
lyophilizer）
, this process is called freeze-drying (
冻干法)
。
Experience has confirmed that supercooling phenomenon arises easily to make the products though temperature reaches the eutectic point.
Important components for the drying oven, coagulator, refrigerating units, vacuum pump, heating/cooling disassembly, etc.
products to freeze in the stationary state.
Freeze-drying process for precool, sublimation and then freeze-dried three phases.
As the pressure landing 13.
Below 3 pa, even free path increases 105 times, sublimate speed is accelerated, rarely change my fly off out of the water molecules, thus formed the directional flow of steam.
the sublimation heat of ice is about 2822 j/g, if don't supply heat sublimation process, then the products only landing internal energy to counter sublimation heat, until its temperature and solidification temperature balance, after checked the sublimation
