Scotch type steam boilers are fully cylindrical, flame-smoke tube boilers characterized by high efficiency and large water volume. Scotch type boilers designed for liquid fuels can operate efficiently with fuels such as Fuel Oil No. 6, Fuel Oil No. 4, and diesel.

In these systems, initial ignition is carried out using diesel fuel. After the steam boiler reaches the required operating pressure, the diesel system can be deactivated and fuel oil combustion can be initiated.

The main fuel tank and daily fuel tank are designed as serpentine-type steam-heated tanks. Fuel oil tanks are heated using steam generated during diesel combustion, and once the fuel temperature reaches approximately 80°C, fuel oil is supplied to the burner via gear pumps to ensure proper combustion.

In liquid fuel boiler systems, the fuel supply system consists of key components such as the main fuel tank, daily fuel tank, diesel tank, fuel heating exchangers, and pot tank. Fuel with the required viscosity is delivered to the burner, while unburned fuel is returned through the return line to the fuel heating exchangers for recirculation and reheating.