Table of Contents
There are safety issues in Spray drying method too like in any other industrial processes. These issues could be dust explosion, solvent explosion, hot surfaces etc.,
In the process of Spray drying, Dust explosion is considered as a major issue. The average dust concentration in the dryer is much lesser than that of the lower explosion concentration. A stronger secondary explosion could be initiated because of the initial explosion because of the dust existing in the cone walls. As a result of rotating spraying wheel, the possible ignition sources can hit the walls of the dryer.
An explosive dust will be produced and suspended in the air during the spray drying process. This explosive dust can create dangers to the employees and other people in the plant and this risk has to be addressed properly. In order to keep the risk at minimum and to prevent the fire, few parameters like minimum ignition temperature (MIT), minimum ignition energy (MIE), minimum auto-ignition temperature, maximum dust explosion pressure Pmax, and dust explosion pressure raise Kst have to keenly monitored.
By monitoring the oxygen concentration inside the spray drier, the explosion dust can be monitored. Oxygen is monitored when the gas leaves. When the oxygen limit exceeds, the plant has to be shut down, so that the opportunity of dust explosion is minimized. (Broze, Dekker, 1999)
2.2.2 Health and environmental issues
The spray drying process creates health and environmental problems as well. (Basketter, English, Wakelin, & White, 2008).The pipes corrosion and emitted granules can affect the employees in the plant and the surrounded environment also.
Emissions of granules
Emitted granules can affect the environment and this is known as containment. (Board, 2006) By using a closed loop process, the risk from emitted granules can be eliminated. Closed loop process can be helpful in eliminating the risks from solvent explosion also.
Solvent explosion is not considered to be a major issue. In order to prevent the risks caused by solvent explosion, Closed loop process can be used in the plant. (Broze, Dekker, 1999) This will protect the employees in the plant from any risks caused by this explosion.
Pipes corrosion can affect the environment as well as the employees in the plant. This risk can be eliminated by monitoring and maintaining the pipes regularly in order to make sure that the pipes are suitable for certain period of time.
When closed loop process is used, no containments will be released to the environment. (Broze, Dekker, 1999) Also, the process has to be monitored properly in order to avoid hazards that can cause danger to employees health and safety.