An Overview of the Spray Drying Process

Spray drying is a quick drying with a hot gas, it converts a liquid or slurry into a dry powder. This is the recommended drying technique for many thermally delicate products, including those used in the food and pharmaceutical industries. Compared to other ways, spray dryers may dry items quite quickly. Additionally they convert liquids into dried powders in a single step, simplifying the process and raising profit margins.

Spray Drying Process

The single effect kind of spray dryers is the most used variety. At the chamber’s top, they use a single supply of drying air. The air often blows in a co-current, which is the same direction as the liquid being sprayed. It generates a fine powder, although it has the potential to flow poorly and generate more dust than other approaches. To tackle the dust and poor powder flow, more recent spray dryers known as multiple effect spray dryers are utilized. The drying procedure comprises two steps rather than drying the liquid in one. Similar to how it is with a single effect dryer, the first step is at the top. 

Application

Spray drying is used in the production of pharmaceuticals to evenly disperse the active medicinal components into a polymer matrix for amorphous solid administration. The medicine’s active ingredients are in a greater degree of energy in this condition, which helps the drug spread throughout the patient’s body. Spray drying is also used in the production of antibiotics, pharmaceutical compounds, and additives.

The food industry use the spray drying encapsulation process to create dehydrated powders from materials that lack water to dehydrate. For instance, to generate instant drink mixes, several chemical components of a beverage are sprayed-dried. Food goods can also be dewatered using this method, such as powdered milk, especially skim. By using lower working temperatures and larger chambers for longer residence times, thermal degradation of products can be minimized. Powdered eggs, coffee, tea, spices, flavorings, enzymes, vitamins, sugar substitutes like stevia, nutraceuticals, colorings, animal feed, and other items are also produced using this method.

Principle

The liquid is reduced to tiny droplets, creating a substantial surface area for the transfer of heat and mass. The drips are sprayed with hot air to dry into solid particles.

Construction

It is made up of drying chambers with conical bases. Every part is made of stainless steel. There is a second intake for the spray disc atomizer at the top, as well as a hot air inlet at the bottom. The drying chamber is attached to a cyclone separator for single-fluid or dual-fluid atomization using nozzles. The dry product is gathered at the separator’s bottom.

Working

Spray drying is a process that turns liquid atomization into dry droplets as it passes through a hot gaseous drying medium. The processes that take place in a spray dryer prior to drying include atomization, spray air mixing, moisture evaporation, and separation of the dry product from the exit air. In spray drying, atomization comes first. The process of atomization involves utilizing a nozzle or rotary atomizer to break up the liquid feedstock into tiny droplets. The solute or suspension is then extracted from the solvent, first as a solid, then as a gas. Many desirable characteristics, including particle size and viscosity, are developed during this phase.

The droplets in the case of atomizers or nozzles dried to create a powder that is simple to transport and package. The droplets solidify once they have dried. In most cases, solids are collected using drums or cyclones. The final product is determined by the design and operation of the spray dryer along with the physicochemical characteristics of the feed. Powder is frequently dried using hot air. The ultimate moisture content of the powder can be managed by varying the hot air temperature. Within a few seconds of the exhaust gas being circulated again, the powder can be extracted from it for recovery.

Uses

  • Many pharmaceutical items, including antibiotics, enzymes, vitamins, yeast, vaccines, and plasma, are produced via spray drying.
  • Spray drying technology is widely used in both pharmaceutical and non-pharmaceutical areas.
  • In addition to other objects, this drying agent can be used to dry things like yeast products, tannin products, bacitracin, penicillin, streptomycin, tetracycline, sulfathiazole, lysine (amino acids), pharmaceutical gums, serums, and spores.
  • Dried liposomes, amorphous medicines, and micro adhesive microspheres can be used to create microcapsules, gastro-resistant microspheres, and controlled-release systems.

At Kerone, we manufacture spray dryers that range in complexity from simple to extremely complicated, depending on the fluid or slurries being processed. The atomization, airstream pattern, air heating systems/technique, separation and collecting unit, and other design elements differ. Spray dryers are primarily made up of a drying chamber, an atomization and dispersion system for supplying fluid into the chamber in tiny droplets, an air heating system, and a separation unit to gather the dried output.

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