Forced circulation is the most rugged type of evaporator specifically designed to handle fouling liquid and crystallisation during evaporation. As a leading forced circulation evaporator manufacturer & supplier in India, our forced circulation type design ensures liquid circulation in calandria (main evaporator heat exchanger body) at high velocity in the 2 to 4 m/s range based on the feed composition. This type of evaporator needs large recirculation flow rates to maintain high velocities across tubes. Axial flow pumps are normally used due to low head and high flow requirements.
The axial flow pump also helps maintain crystal size, allowing the crystal to pass through with minimum grinding across the pump. Usually, forced circulation evaporator design uses single pass construction in vertical installation and two pass construction in horizontal construction. More than two pass design is not desirable as forced circulation type evaporators can have pool boiling and cavitation possibilities which can compromise plant life, cleaning cycle duration and life of the mechanical seal.