Comparison between open spray drying equipment and closed circulation spray drying equipment
I. Open spray drying system
It is characterized by: the heating body in this system only once to be discharged into the atmosphere, not recycling. Suitable for high moisture content in the exhaust gas, non-toxic odorless gas, into the atmosphere does not affect the situation of environmental pollution.
Open air spray drying system system is relatively simple, air (or other heating body) by the blower through the filter inhalation, sent to the heater is heated to hot air, through the top of the drying tower hot air distributor, even into the tower. The raw material to be dried is pumped from the feed to the airflow atomizer, and the droplets are dried into the granular product by contact with the hot air and discharged continuously from the cyclone dust collector at the bottom of the drying tower. The purified exhaust gas is discharged into the atmosphere by the exhaust fan. Pressure spray, centrifugal spray, air spray can be designed in accordance with open system. The main drawback of this system is that the heating load is relatively large.
2. Closed circulation spray drying system
It is characterized by: the heating body in this system to form a closed loop, is conducive to saving heating body, recycling organic solvents, to prevent toxic substances pollution of the atmosphere. The use of liquid material is often containing organic solvents, or is easy to oxidize, flammable, explosive materials, but also for toxic materials, so the heating medium mostly use inert gas "such as nitrogen, carbon dioxide, etc.). The exhaust gas from the drying tower is removed by cyclone dust particles, and then into the condenser. The role of the condenser is the state of the exhaust gas (or moisture) condensed down. After the surge of the exhaust gas by the blower, into an indirect heater and then become hot air, so repeated use.