Working principle of closed cycle spray tower
Different from the traditional open spray dryer (using air, products and waste gas are discharged directly), the working process of the closed cycle system is as follows:
Closed loop gas circulation: The system is filled with an inert gas (most commonly nitrogen, N ₂) instead of air. This completely eliminates oxygen and creates a dry environment without oxygen.
Drying and evaporation:
The liquid (usually an organic solvent solution) is pumped to the atomizer (centrifugal or pressure type) at the top of the drying tower and dispersed into fine droplets.
After being heated by the heater, the circulating inert gas is sent into the tower to come into contact with the droplets.
In a very short period of time, the organic solvents in the droplets are rapidly evaporated.
Gas solid separation:
The dried product powder falls into the bottom of the tower for collection.
Wet inert gas carrying solvent vapor and a small amount of fine powder is discharged from the bottom of the tower.
Solvent condensation recovery:
Wet inert gas enters a condenser. Here, solvent vapors in the gas are condensed into liquid form through low-temperature cooling (usually using cold water or frozen saltwater).
The liquid solvent is collected in the solvent recovery tank, which can achieve the recycling and utilization of the solvent, save costs, and be environmentally friendly.
Gas reheating and circulation:
The cold inert gas coming out of the condenser has now become 'dry' (with extremely low solvent content).
The gas is transported to the heater for reheating through a blower.
The heated inert gas is sent back into the drying tower to start a new cycle.
Throughout the entire process, inert gas is constantly circulated in the closed loop of "heater → drying tower → condenser → blower → heater", with only a small amount of gas added to maintain system pressure balance.