Currently, thermic fluid heater boiler is being widely used in various applications for indirect heating process. By using petroleum fluids as heat transfer medium, these heaters provide constant temperature. Combustion system consists of fixed grate with mechanical draft arrangements.
Modern oil-fired thermic fluid heater boiler consists of double coil, constructed with three passes and is fitted with pressure jet system. Thermic fluid, which acts as a heat carrier, is heated in the heater and circulated through the user’s equipment. Fluids transfer heat through heat exchanger to the process, and thereafter the fluid is returned to the heater.
Thermic fluid flow at the user end is controlled by a control valve that is pneumatically operated, based on the operating temperature. Heater operates at either high fire or low fire depending on the return oil temperature which again varies depending on system load.
The advantages of thermic fluid heater are:
-> It is a closed operating system with minimum losses as compared to steam boilers.
-> Operating system is not pressurized even for temperatures around 250 C compared to the needs of the steam pressure of 40 kg/cm2 in a similar steam system.
-> Automatic control settings, which provide operational flexibility.
-> Thermal efficiency is good because there is no heat loss caused by blow down, discharge condensate and flash steam.
The overall economic viability of thermic fluid heater boiler depend upon the specific application and the reference basis. The coal-fired thermic fluid heater boiler has a thermal efficiency range of 55-65%. Thermic fluid heater boiler is more comfortable to use than the most common boiler.
Incorporation of heat recovery devices in the exhaust gas will further enhance the thermal efficiency.