Spray drying is a process that uses hot gas to quickly dry a liquid or slurry into a dry powder. Many thermally sensitive products, such as foods and pharmaceuticals, as well as those requiring extremely constant, tiny particle sizes, favor this type of drying. The heated drying medium is air; however, nitrogen is used instead of the liquid that is flammable, such as ethanol, or if the product is oxygen-sensitive. ALAQUA is a spray dryer supplier as well as other processing equipment suppliers like evaporators, crystallizers, heat exchangers, distillation equipment, and solvent recovery systems.
A spray dryer takes a liquid stream and turns the solute or suspension into a solid while vaporizing the solvent. A drum or cyclone is commonly used to gather the solid. A nozzle sprays the liquid input stream into a hot vapor stream, which is then vaporized. As the moisture from the droplets evaporates, solids form. To maximize heat transfer and the rate of water vaporization, a nozzle is typically utilized to make the droplets as tiny as feasible. Depending on the nozzle, droplet sizes can vary from 20 to 180 m. There are two types of nozzles: single-fluid high-pressure nozzles and two-fluid nozzles, with one fluid being the liquid to dry and the other being compressed gas.
When compared to other drying technologies, spray dryers can dry a product quite quickly. They also convert a solution (or slurry) to a dried powder in one step, simplifying the process and increasing profit margins.
Spray drying is used in pharmaceutical manufacturing to uniformly disperse Active Pharmaceutical Ingredients into a polymer matrix, resulting in Amorphous Solid Dispensation. This state will raise the energy level of the active chemicals (drug), allowing for easier drug spice dispersion in the patient’s body.
Principle of Spray Drying Method
There are a variety of drying processes available, but spray drying is the most popular. It entails atomizing the liquid to be dried into tiny droplets in the drying chamber, allowing the droplets to come into direct contact with and mix with the hot gas of the drying medium to evaporate the water, and then collecting the water via gas-solid separation to obtain a powder or granular product. A solution, an emulsion, or a suspension, as well as a molten liquid or a paste, may be used as the raw material liquid. Air, nitrogen, or superheated steam can all be used for drying.
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Applications of Spray Drying Method
The spray drying method is particularly popular among customers in the pharmaceutical and food industries because spray drying machines can meet the GMP criteria in both fields and provide superior results. It works well for drying and granulating Chinese and Western medications and foods. Granules made for tableting, capsule filling, granules, and solid drinks have strong disintegration, good fluidity, and fast solubility, and can be used directly for tableting, capsule filling, granules, and solid beverages.
In dye drying, the spray drying process is also used. Fine powder, super-fine powder, dust-free powder, and hollow granules can all be dry dyed using it. This procedure is divided into three groups:
- Airflow Atomization, which uses compressed air or water vapor to atomize the material liquid;
- Pressure Atomization, which uses a high-pressure pump to force the material liquid out of the nozzle at a high rate, resulting in a mist;
- Rotary Atomization, where the liquid material is introduced to the atomizer’s high-speed spinning disc (7000–28000r / min), then swiftly flung out and atomized. The dyestuff business prefers the third type, rotational atomization, because it has a good effect, takes little time, and has high labor productivity. However, it necessitates a significant capital investment and substantial energy usage.
Spray drying is an example of material drying technology that has been implemented in a systematic way. The moisture swiftly evaporates in contact with the heated air once the material is atomized in the drying chamber, resulting in the dried product. Evaporation and crushing can be avoided with this strategy. Quick heat transfer, short water evaporation, and quick drying time are all advantages of spray drying. It can speed up the dissolution of some formulations, making it ideal for heat-sensitive medications. Microcapsules can also be made by spray drying.
Advantages of Spray Drying Method
- Process of rapid drying
- Drying materials directly into powder is possible.
- It’s simple to tweak product quality criteria and vary drying conditions.
- In the drying chamber, there is a slight negative pressure, which ensures hygienic conditions in the manufacturing process, prevents dust from blowing around the workshop, and increases product purity.
- There are fewer operators and higher manufacturing efficiency.
- High-quality products with a large production capacity Several hundred tonnes of spray can be applied in an hour.
Disadvantages of Spray Drying Method
- The machinery is complicated, covers a wide area, and demands a significant financial investment.
- A spray dryer and powder recovery system costs a lot of money.
- The heat consumption is significant and the thermal efficiency is low.