A combi boiler or combination boiler is the most commonly used boiler in India. Combi Boiler is a unique membrane design water wall type boiler which combines the advantages of both water tube & smoke tube steam boilers. A combination type of steam boiler is the one which has the operational characteristics of both smoke tube and water tube steam boiler respectively. Unlike the packaged type Boilers, here the furnace is external to the boiler shell. During its operation, the combustion takes place in the water wall so the flue gases from here travel in this membrane (as in a Water Tube Boiler) and enter the Boiler shell. Now the flue gases travel in the smoke tubes (as in a Smoke Tube Boiler).
During its course of motion, it transfers heat to the –
- Water present in the tubes in the Water Wall Membrane
- Water present in the Boiler shell through tubes
This type of steam boiler offers the high degree of reliability and trouble free operation. They effectively operate at moderately high pressures and steam flow capacities, unlike packaged type smoke tube boilers.