Spray Drying
1. Brief Introduction
Spray drying is a method of systematic technology applied to material drying. After atomizing the thinner in the drying chamber, the moisture will vaporize rapidly in contact with the hot air to obtain the dried product. This method can directly dry the solution and emulsion into powder or granular products and can save the processes of evaporation and crushing.
2. Working principle
Through mechanical action, the materials to be dried are dispersed into very fine particles like fog, which (increases the evaporation area of water and accelerates the drying process) contact with hot air, and most of the water is removed instantly so that the solid materials in the materials are dried into powder.
(1) Pressure spray drying method:
① Principle: A high-pressure pump is used to pass the materials through the atomizer (spray gun) at 70~200 atmospheric pressure to form 10~200 foggy particles to direct contact with hot air for heat exchange and complete drying in a short time.
② Pressure spray atomization device: M-type and S-type, with guide grooves that rotate the liquid flow. The axis of the M-type guide groove is perpendicular to the nozzle axis and does not intersect with it; The axis of the S-shaped guide ditch is at a certain angle with the horizontal. The purpose is to increase the turbulence of the solution during spray.
(2) Centrifugal spray drying method:
① Principle, The droplets are dispersed into tiny droplets and move along the cutting direction of the disc at an average speed. At the same time, the droplets are attracted by the earth's center and fall down. Because of the different sizes of the particles sprayed. Therefore, their flying distances are different, so the particles fall at different distances from a cylinder symmetrical to the center of the rotation axis.
② Requirements for obtaining more uniform droplets: a. reduce the vibration when the disk rotates b. keep the amount of liquid entering the disk constant in unit time c. the disk surface is flat and smooth d The circular velocity of the disk should not be too small, Rmin = 60m / s if the milk (100-160m / s) is less than 60m / s, the spray droplets are uneven, and the spray distance seems to be mainly composed of a group of droplets and a group of fine droplets sinking near the disk, and decreases with the increase of the rotation speed.
③ Structure of centrifugal spray: it is required that the wetted periphery is long, the solution can reach high rotation speed, the spray is uniform, the structure is firm, the mass is light, the structure is simple, there is no dead angle, it is easy to disassemble and wash, and the productivity is high.
(3) Airflow spray drying method:
Principle: The wet material enters the dryer through the conveyor and the heated natural air at the same time. The two are fully mixed. Due to the large heat and mass exchange area, the purpose of evaporation and drying can be achieved in a short time. The dried finished products are discharged from the cyclone separator, and a small part of the fly powder is recycled by the cyclone or bag filter.
Freeze Drying
1. Brief Introduction
Freeze dryingis to cool down and freeze a substance containing a large amount of water into a solid in advance, and then sublimate the solid water directly under vacuum conditions, while the substance itself remains in the frozen ice shelf, so its volume remains unchanged after drying. Solid water should absorb heat during sublimation, causing the temperature of the product to drop and slowing down the sublimation speed. In order to increase the sublimation speed and shorten the drying time, the product must be properly heated. The whole drying is carried out at a lower temperature.
2. Advantages of freeze-drying
（1）Freeze drying is carried out at low temperatures, so it is especially suitable for many heat-sensitive substances. For example, proteins and microorganisms will not denature or lose biological vitality. Therefore, it is widely used in medicine.
（2）When drying at low temperatures, the loss of some volatile components in the substance is very small, which is suitable for drying some chemical products, drugs, and food.
（3）In the process of freeze-drying, the growth of microorganisms and the role of enzymes cannot be carried out, so the original properties can be maintained.
（4）Because it is dried in the frozen state, the volume is almost unchanged, the original structure is maintained, and no concentration occurs.
（5）The dried substance is dissolved rapidly and completely after adding water, and almost immediately recovers its original properties.
（6）As drying is carried out under a vacuum, there is little oxygen, so some easily oxidized substances are protected.
（7）Drying can remove more than 95-99% of water so that the dried product can be stored for a long time without deterioration.
Therefore, freeze-drying is widely used in the pharmaceutical industry, food industry, scientific research, and other departments.
Application
Spray-drying technology and freeze-drying technology are widely used and mature in the production of fruit powder.
Ciyuan Bio can provide you with various spray-dried powder products and freeze-dried powder products. We can not only provide you with powder products but also conduct deep processing for you. For example, if the powder is used, it can be processed into soft candy, tablet candy, and drinks for you.
