Spray drying produces spherical particles of about 300 micro metre (0.012 in) size with a density of 0.22 g/cm3. To achieve this, nozzle atomization is used. Various ways of nozzle atomization can be used, each having its own advantages and disadvantages. High speed rotating wheels operating at speeds of about 20,000 rpm are able to process up to 60,000 pounds (27 tonnes) of solution per hour.
- Completed in 5-30 seconds (depending on factors such as heat, size of particle, and diameter of chamber).
- Moisture content change: IN = 75-85% OUT = 3-3.5%
Challenges in Spray Drying
Spray dryers require large quantities of hot air for drying. The quality of the final product is affected by the quality of inlet air entering the dryer. The Spray Dryer mixes heated air with an atomized (sprayed) liquid stream within a vessel (drying chamber) which leads to evaporation and produces free-flowing dry powder with a controlled average particle size. Thus, the inlet air has to be dry, free of contamination, foreign particles and odourless. However, since the ambient changes throughout 24 hrs, 365 days a year, the humidity present in the air, entering the spray dryer is not constant. Thus, the drying temperature and time inside the dryer needs close monitoring to restrict loss due to varying levels of humidity present in the inlet air. These varying inlet conditions need to be monitored by an experienced operator to adjust the parameters for a stable outlet condition.
- Throughput varies with outside environmental conditions
- Extra moisture in the inlet air increases drying cycle time
- Varying outside conditions result in inconsistent powder quality
- Higher downtime due to sticking of material on Spray Dryer walls
Bry-Air Solution
Bry-Air has specially developed high performance dehumidifiers for supplying precisely controlled, stable and consistent dehumidified air to the inlet of spray dryers. Providing stable and consistent inlet air enables higher performance and output from spray dryers and improves the quality of coffee powder. It reduces your dependence on operator for a constant adjustment of parameters on account of varying outside environment. It also reduces your energy bills of heater for heating the inlet air up to the required temperature. Dehumidifying the inlet air also increases its temperature, as a result of which the heater has to do less work now to heat the air to the required temperature.
At HUL -The fresh air is taken through the Bry-Air dehumidifier after pre-cooling, and the outlet of dehumidifier, which is at lower grains, is further heated and passed to the Spray drier.
Benefits of Inlet Air Dehumidification
The dehumidification of the air helps tea and coffee to dry fast, and allows smooth and free flow operations. Bry-Air has developed a range of special high performance dehumidifiers which enable this to happen. Bry-Air dehumidifiers control precisely the moisture content of the incoming air. It results in following advantages:
- Stable & consistent Drying Conditions throughout the year with no affect of outside conditions
- Reduced dependence on operator for constant monitoring and parameter adjustment
- Increased efficiency and throughput -up to 30% in some cases
- Improve rate of solution by avoidance of the clumping caused by fine particles
Bry-Air Advantages
- Short set-up time
- Precise and consistent results
- Lowest energy consumption
- Widest service network
