What are liquid fuels used in power plants?

Short Answer:

Liquid fuels are fuels that exist in liquid form under normal conditions and are widely used in power plants for generating heat energy. The most common liquid fuels used in power plants are furnace oil, diesel oil, kerosene, crude oil, and heavy fuel oil. These fuels are burned in boilers or combustion chambers to produce heat for steam generation or direct power production in gas turbines.

In simple words, liquid fuels are energy sources such as oil-based products that burn easily and produce large amounts of heat. They are used in power plants because they are easy to store, handle, transport, and burn cleanly, making them suitable for both small and large power generation systems.

Detailed Explanation :

Liquid Fuels Used in Power Plants

Liquid fuels are energy-rich substances that are liquid at room temperature and used widely in thermal and gas turbine power plants to produce heat energy. These fuels are generally derived from petroleum (crude oil) through the process of refining. Compared to solid fuels, liquid fuels have several advantages such as ease of handling, uniform combustion, and high calorific value.

In power plants, liquid fuels are used to generate steam in boilers or as direct fuel in gas turbines and diesel engines for electricity generation. They are particularly useful in areas where solid fuels like coal are not easily available or when quick starting of the power plant is needed.

The main liquid fuels used in power plants include:

  1. Furnace Oil
  2. Diesel Oil
  3. Kerosene
  4. Crude Oil
  5. Heavy Fuel Oil
  1. Furnace Oil

Furnace oil (also called fuel oil or residual oil) is one of the most common liquid fuels used in large thermal power plants. It is obtained as a residue during the distillation of crude oil in petroleum refineries.

Characteristics:

  • Dark brown or black in color.
  • High viscosity and requires preheating before combustion.
  • Calorific value: about 40,000 – 42,000 kJ/kg.

Use in Power Plants:
Furnace oil is burned in specially designed burners in boilers to produce heat, which converts water into steam. This steam drives turbines for power generation.

Advantages:

  • High calorific value.
  • Suitable for large-scale, continuous power generation.
  • Produces steady and controlled flames.

Disadvantages:

  • Produces sulfur oxides during combustion.
  • Needs heating systems for storage and burning due to high viscosity.
  1. Diesel Oil

Diesel oil is a medium-grade refined fuel obtained from petroleum. It is also known as light fuel oil and is widely used in diesel engine power plants and small generating units.

Characteristics:

  • Calorific value: about 43,000 – 45,000 kJ/kg.
  • Burns easily and does not require preheating.
  • Produces less ash and smoke.

Use in Power Plants:
Diesel oil is mainly used in diesel engine power plants for small-scale or standby electricity generation. It is ideal for remote areas, emergency backup systems, and places where grid supply is unavailable.

Advantages:

  • Easy ignition and smooth combustion.
  • Suitable for quick start and stop operations.
  • Portable and easy to store.

Disadvantages:

  • Expensive compared to coal and furnace oil.
  • Not suitable for large-scale continuous power generation.
  1. Kerosene

Kerosene is a light, refined petroleum product obtained during the fractional distillation of crude oil. It is a clean-burning fuel and is mainly used in small power plants and gas turbine engines.

Characteristics:

  • Calorific value: around 46,000 kJ/kg.
  • Low viscosity and burns with a blue flame.
  • Contains fewer impurities than heavy oils.

Use in Power Plants:
Kerosene is used in small gas turbines and aviation turbine engines as a starting fuel or for short-duration power production.

Advantages:

  • High calorific value and clean combustion.
  • Does not require preheating.
  • Produces little smoke or ash.

Disadvantages:

  • Costly for large-scale use.
  • Limited availability for industrial purposes due to domestic demand.
  1. Crude Oil

Crude oil is a natural petroleum found in underground reservoirs. It is a complex mixture of hydrocarbons, which is refined to produce various liquid fuels like gasoline, diesel, and furnace oil.

Characteristics:

  • Calorific value: around 45,000 kJ/kg.
  • High energy content but requires special burners and control systems.
  • Contains impurities like sulfur and metals.

Use in Power Plants:
Crude oil is directly used in some power plants equipped with advanced combustion systems. It serves as a primary fuel in oil-fired power plants, particularly in regions where petroleum resources are easily available.

Advantages:

  • High heat output per unit mass.
  • Easy to transport through pipelines.

Disadvantages:

  • Produces more pollutants if not refined.
  • Expensive compared to refined fuels.
  1. Heavy Fuel Oil

Heavy fuel oil (HFO) is a thick, viscous petroleum product that remains after lighter fractions are removed during refining. It is mainly used in large industrial boilers and marine power plants.

Characteristics:

  • Calorific value: about 40,000 kJ/kg.
  • Requires preheating for pumping and atomization.
  • Contains sulfur and impurities.

Use in Power Plants:
HFO is commonly used in large thermal power plants and marine diesel engines. It provides stable combustion and steady heat output for continuous operation.

Advantages:

  • Cheaper than lighter fuels.
  • Suitable for high-capacity plants.

Disadvantages:

  • Requires complex fuel handling systems.
  • Generates pollutants such as SO₂ and particulates.
  1. Advantages of Liquid Fuels in Power Plants
  1. High Calorific Value: Produces more heat per kilogram compared to solid fuels.
  2. Easy Handling: Can be pumped, stored, and transported through pipelines.
  3. Clean Combustion: Produces less ash and soot.
  4. Quick Start-Up: Suitable for emergency or standby power plants.
  5. Uniform Combustion: Ensures efficient burning and heat transfer in boilers.
  1. Disadvantages of Liquid Fuels
  1. High Cost: Petroleum-based fuels are expensive.
  2. Pollution: Emits sulfur oxides and carbon dioxide when burned.
  3. Fire Hazard: Highly flammable and requires safe storage.
  4. Limited Availability: Dependent on petroleum reserves.
  1. Applications in Power Plants

Liquid fuels are mainly used in:

  • Diesel power plants for small-scale generation.
  • Gas turbine plants using kerosene or diesel.
  • Steam power plants as standby or auxiliary fuel with coal.
  • Marine power systems where heavy fuel oils are preferred.

They are especially valuable for remote locations, islands, or military bases, where fuel supply through pipelines is more practical than transporting solid fuels.

Conclusion

The liquid fuels used in power plants include furnace oil, diesel oil, kerosene, crude oil, and heavy fuel oil. These fuels are mainly derived from petroleum and are preferred for their high calorific value, ease of handling, and clean combustion. They are used in various types of power plants such as thermal, diesel, and gas turbine plants. Although liquid fuels are more expensive than solid fuels, their operational convenience, quick start-up capability, and suitability for remote installations make them highly valuable for reliable and flexible power generation.