Before firing liq. fuel, atomising steam is used to atomised fuel for complete combustion in boiler?

Question

Before firing liq. fuel, atomising steam is used to atomised fuel for complete combustion in boilers, why atomising steam temprature reduced with water before it introduced in burner with liq. fuel ? please explain me.

Answer 1

YNOT is spot on.

To further answer why water is added to steam.

When high temperature steam is reduced in pressure it becomes super heated steam. The temperature of super heated steam is higher than its saturation temperature and the steam is dry.
In other words superheated steam is hotter than the temperature it takes to boil water at that pressure and is 100% dry all the moisture has been converted into steam.

To reduce the superheated steam temperature to that of saturated steam water is sprayed into the steam line just after it has been reduced in pressure. The sprayer is called an atemperator which uses water to cool dry superheated steam and convert it into moist saturated steam.

Atomizing steam is passed through the burner barrel to the tip while Fuel oil is also passed down a tube in the center of the burner barrel. The steam typically surrounds the fuel oil which preheats the fuel and cools the burner barrel.

Over heating the fuel oil will cause the fuel to carbonize within the burner barrel clogging the passages and burner tip.

If the atomizing steam is super heated it is more likely to cause fuel oil carbonizing than saturated steam.

Also saturated steam (wet steam) has a greater cooling capacity than superheated steam. One way of controlling the firing rate in a boiler is to secure the fuel to the burner. The atomizing steam is allowed to flow into the firing chamber while the burner is placed in stand-by. The flow of steam through the burner keeps the tip cool and prevents damage from the heat of adjacent burners still on line. This is a common practice on ships during maneuvering

And finally wet steam or saturated steam has a greater amount of expansion when heated compared to dry superheated steam. This expansion further aids atomization.

Answer 2

The steam atomising burner injects high pressure steam into the burner tip. This helps convert the liquid fuel (usually a heavy fuel oil) into a finely atomised spray, for rapid efficient combustion inside the boiler combustion chamber.

Why use high pressure steam? Because it is usually readily available from the boiler itself, it doesn't reduce the boiler efficiency significantly because it is already hot, and it doesn't affect the exhaust gasses, as steam is one of the products of combustion anyway.

Steam atomising burners are only used when convenient. Air atomising or air blown burners are also commonly used for steam boilers.

Answer 3

I am really looking forward to this Ashes series and certainly haven't completely written the Aussies off. Having said that England must go into the series as overwhelming favourites due to recent form and the fact that the series is being played in England. I reckon Chris Rogers could be a bit of a dark horse as he knows the conditions over here pretty well. Good to see some friendly banter flying around between the 2 sets of supporters too!

Answer 4

Atomising