Furnace Fuel Oil Atomisation To Stop Wastage And Improve Efficiency In Hydrocarbon Plants

Steam atomising is widely used in hydrocarbon plants to increase the efficiency of fuel oil burners since steam is readily available and is less expensive than compressed air.

Ensuring Complete Fuel Oil Combustion

Since, fuel oil does not burn easily in the liquid state, the following aspects are important to ensure
complete fuel oil combustion.

1. the fuel oil atomises thoroughly into tiny droplets, so surface area increases exponentially
2. the tiny droplets thoroughly mix with a sufficient amount of air; excess must be kept at a
minimum to reduce thermal stack loss
3. the correct ratio of fuel oil to forced draft air should be maintained to maximise fuel
combustion

Steam atomizing helps in breaking up fuel oil particles into tiny droplets, facilitating easy spread of oil inside the furnace, and maximising combustion. The result is a well spread and intense flame.

Without the injection of steam into the burner, the physical state of fuel oil will remain in a liquid form. In order to burn this liquid oil, maximum excess air will be needed, and the combustion process will also be longer. Another scenario would be that the liquid oil will drip, and eventually puddle without burning. Some of the fuel oil may also spill, creating a hazard for surrounding areas. This phenomenon is called “oil spillage”.

Efficient Steam Atomisation

The two aspects most neglected in a steam atomizing system are steam wetness and fuel oil
temperature :

• Steam must be dry saturated or superheated. If steam itself is wet, then it will eventually mix
with oil and drastically reduce the burner efficiency
• Temperature of fuel oil fed to the burner needs to be almost at boiling point to facilitate
complete combustion

To overcome these problems,

it is recommended that the moisture separator be installed upstream of the steam line, with the right type of steam trap to discharge condensate as soon as it forms. Proper steam tracing of the fuel oil line must be done to maintain the temperature from preheater to end user. Group trapping should be eliminated, and individual thermodynamic traps installed for best results in improved efficiency.