FUEL OIL: In industries, the most commonly used fuel oil is heavy fuel oil (also called "industrial fuel oil" or "furnace oil"), which is a thick, residual product from crude oil refining, primarily used to generate heat in industrial boilers and furnaces for power generation and industrial heating processes. Key points about industrial fuel oil: Heavy viscosity: Due to its high viscosity, it needs specialized handling and burning equipment. Cost-effective: Often considered a cost-effective option for large-scale heat generation. Different grades: Depending on the specific needs of the industry, different grades of heavy fuel oil are available with varying viscosity levels. Other fuel oils used in specific industrial applications: Diesel: Used in industrial machinery and vehicles due to its high energy density and efficient combustion. Kerosene: Employed in smaller industrial heating applications where a lighter fuel is needed. Industrial heating oil: A refined fuel oil suitable for commercial boilers and industrial heating systems.