[[TitleIndustry]]

Three common ways and principles of spray drying

Date:Nov 13, 2019

Spray drying machine

Spray drying is a method that can complete drying and granulation at the same time, and can directly make the solution, emulsion and suspension dry into powder or granular products, eliminating evaporation, crushing and other processes.By mechanical action, the material to be dried can be dispersed into particles, and let most of the moisture removed, so that the solid material in the material dried into powder.

At present, spray drying is widely used in the rapid drying of liquid materials, which is suitable for medicine and other fields.According to the introduction of relevant technical personnel, spray drying methods are mainly pressure type, centrifugal type, air flow three.

Pressure spray drying

The principle of pressure spray drying method is to use a high pressure pump to condense the material through the atomizer (spray gun) into atomized particles in direct contact with hot air for heat exchange and complete drying in a short time.

The pressure spray microfluidization device has two guide channels to rotate the liquid in order to increase the turbulence of the solution during the spray.One kind of guide groove axis is perpendicular to the nozzle axis and does not intersect with it.The other is the guide groove axis and horizontal into a certain Angle.

Centrifugal spray drying

Principle of centrifugal spray drying method is that the horizontal direction is used as the high speed rotating disk to give solution to centrifugal force, to make it out at high speed, the formation of thin films, filament or droplets, due to air friction, obstacles, the action of tear, with tangential acceleration produced by the rotation of the disc and the centrifugal force produced by the radial acceleration, the results on the disc in a match speed movement, its trajectory is a spiral, liquid along the helix since thrown on the disk is dispersed into a very tiny droplets in the disc diameter cutting direction, the average speed droplets and fall by gravity and at the same time, due to the spray particle size is different,Thus they fly at different distances, and the falling particles form a cylinder symmetrical to the center of the axis of rotation.

Technicians say that the way to get more even droplets using centrifugal spray drying is to reduce the vibration of the disk as it rotates.When the amount of liquid entering the disc remains constant per unit time, the surface of the disc is kept flat and smooth.In addition, the circular speed of the disk should not be too small.

Centrifugal spray dryer is a kind of drying equipment suitable for drying liquid such as emulsion, suspension, paste and solution.The equipment is fast in drying, suitable for the drying of heat sensitive materials, can maintain the color, aroma and taste of materials, and easy to operate and control, suitable for continuous control of production, product dispersion, liquidity, solubility is good, at present in medicine and other fields widely used.

Air flow spray drying

The working principle of air-flow spray drying method is that wet materials enter the dryer at the same time through the conveyor and the heated natural air, and the two are fully mixed. Due to the large heat and mass exchange area, the purpose of evaporative drying can be achieved in a very short time.After drying, the finished products are discharged from the cyclone separator, and a small part of fly powder is recycled by the cyclone dust collector or bag dust collector.

It is reported that the air flow spray dryer mainly has four forms, one is the air flow dryer is negative pressure operation, the material does not go through the fan;The second is the air drying is positive pressure operation, the material after the fan with crushing effect;The third type of air dryer is tail gas circulation type.The fourth type of air drying is the enhanced air drying device, which integrates flash drying and air drying. This type of spray drying device is a new type of spray drying device designed by our factory according to the needs of users.


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