Spray Dryer
Principle
It atomizes the liquid into small droplets, providing a large surface for mass and heat transfer. Using hot air, the drops are sprayed so that they dry into solid particles.Constructions
Drying chambers with conical bases comprise it. All the parts are stainless steel. An inlet for hot air is also provided at the bottom, and a second one is provided at the top for the spray disk atomizer. A cyclone separator is connected to the drying chamber for atomization using single-fluid or dual-fluid nozzles. In the bottom of the separator, the dry product is collected.Working
When moved through a hot gaseous drying medium, spray drying produces dry droplets from liquid atomization. Atomization, mixing spray air, evaporation of moisture, and separation of the dry product from the exit air are the steps before drying occurs in a spray dryer. Atomization is the first step in spray drying. Atomization is the act of turning the liquid feedstock into small droplets of liquid by using a nozzle or rotary atomizer. Following, the solute or suspension is separated from the solvent as a solid and then into a gas. As part of this stage, many desirable properties are developed, such as particle size and viscosity.In the case of atomizers or nozzles, the droplets dried to form a powder that is easily packaged and transported. After the droplets have dried, they form solids. Drums or cyclones are usually used to collect solids. The spray dryer's design and operation, coupled with the physicochemical properties of the feed, determine the final product. Hot air is commonly used to dry powder. By adjusting the hot air temperature, the powder's final moisture content can be controlled. After the exhaust gas has been re-circulated, the powder can be recovered from it within a few seconds during the recovery process.
Uses
- In both pharmaceutical and non-pharmaceutical fields, spray drying technology is widely used.
- Spray drying is used in the production of many pharmaceutical products, such as antibiotics, enzymes, vitamins, yeast, vaccines, and plasma.
- This drying agent can be used to dry algae, antibiotics and molds, bacitracin, penicillin, streptomycin, tetracycline, sulfathiazole, lysine (amino acids), pharmaceutical gums, serums, spores, tableting constituents, vaccines, vitamins, yeast products and tannin products, among others.
- In terms of making tablets and granules, spray drying stands out as a unique process. Indirect tableting of controlled release matrix tablets using composite particles with excellent micrometric properties. Theophylline, magnesium carbonate, and acetaminophen have been granulated with it. Spray drying of amorphous lactose and sodium alginate results in spherical composite particles.
- Dry powder aerosol formulations can be prepared using it. Salbutamol sulfate particles prepared by spray drying in an inhaler are two examples. Liposomal ciprofloxacin powder is also used.
- Microcapsules, gastro-resistant microspheres, and controlled-release systems can be fabricated using dried liposomes, amorphous drugs, and mucoadhesive microspheres.
- Solids and liquids have been coated and encapsulated with spray drying. In an aqueous system, theophylline microparticles were coated with a polymer and spray dried.
- Spray drying various liquids can be used to prepare dry emulsions. For example, coconut oil fractionated emulsions dispersed in aqueous solutions of HPMC (solid carrier).
- Dry elixirs can also be prepared with it. An example would be Flurbiprofen Dry Elixir.
- The food, chemical, and ceramic industries use spray drying to dry a variety of materials other than pharmaceuticals. The list of products can be as diverse as: detergents, soaps, and surface-active agents, pesticides, herbicides, fungicides and insecticides, dyestuffs, pigments, fertilizers, mineral suspension concentrates, inorganic chemicals, organic chemicals, spray concentrates (purification), milk products, eggs products, food, and plant products, fruits, vegetables, carbohydrates, as well as slaughterhouse products, fish products, and many more.
Merits
- During the drying process, the process takes between 3 and 30 seconds.
- Since it is an ongoing process, it is less labor intensive.
- Product sizes can be controlled and uniform.
- The product produced is highly concentrated and has excellent solubility.
- It is very easy to dry solutions or suspensions.
- Sterilized products can be dried with it.
Demerits
- Equipment is bulky and expensive to install, as well as ancillary equipment components.
- Consequently, a large volume of heated air passes through the chamber without contacting any particles, resulting in a low thermal efficiency.
- Keeping it clean after use is a challenge.
- Because it requires liquid material to be dried, spray dryers cannot be used to dry solid materials.
- The deposit of a product in the drying chamber may result in product degradation or a fire hazard.
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