For a great number of medicines, drying is an indispensable process, which has a good effect on the efficacy of medicines. And spray drying technology is one of the more advanced drying technologies in the pharmaceutical industry.
Spray drying is a commonly used technology for liquid materials at present, especially in the production of traditional Chinese medicine. It has been used in the pharmaceutical industry for decades. Its application greatly simplifies and shortens the process and time from extracting solution of traditional Chinese medicine to semi-finished or finished product, improving production efficiency and product quality.
Definition of Spray Drying
Roughly speaking, spray drying refers to the process where solution, emulsion, suspension, and other forms of slurry are sprayed into small droplets in the hot air, and then become powdered or granular product by evaporating water as it falls.
Working Principle of Spray Drying
A spray dryer belongs to a kind of hot air direct drying equipment. When working, the atomizer (nozzle) decomposes the raw liquid material into droplets and sprays them into the hot air with the temperature of 120 ~ 300℃. It can dry materials rapidly within a few seconds to a dozen seconds by utilizing the velocity difference between droplets moving and hot air. The raw materials can be solution, emulsion, suspension, melt or paste liquid. The dry products can be made into powder, granule, pellet or even hollow ball according to the technological requirements. The spray drying technology can be divided into pressure spray drying, centrifugal spray drying, air flow spray drying.
Advantages of Spray Drying
- The production process is simplified and the operation process is convenient. Spray drying can directly dry liquid materials into solid products, which simplifies a series operations, such as evaporation, crystallization, separation, drying and grinding required by the traditional process. Besides, it is convenient to regulate the particle size, bulk density and moisture content of products by changing operating conditions.
- It can dry rapidly. The drying time is generally from 5 to 30 seconds with a large surface area of gas-solid contact. It is especially suitable for drying heat sensitive materials.
- The dry products feature good dispersity, fluidity and solubility.
- It can protect our environment from contamination due to spray drying is carried out in an airtight container.
- Spray drying can be operated continuously, meeting the requirements of industrial mass production.
Applications of Spray Drying in Pharmaceutical Industry
Spray drying can be used for drying extracts of traditional Chinese medicine. Compared to traditional drying methods, liquid materials can be charged directly and dried by hot air in liquid form. The material is exposed to the hot air fully with a rapid drying speed. It can be used for granulating process, microcapsule preparation, coating technology as well.