This is especially prominent in boilers using heavy fuel oil for burning. Although fuel will be heated and filtered before combustion, it still contains a lot of impurities. The by-products of combustion as well as imperfect combustion cause soot to form. The soot is deposited on heating surfaces.

During combustion of fuel oil in a steam boiler, hot gases are formed. These hot gases are used to heat up water in boiler to form steam.

With deposits of soot, a lot of heat energy is not able to be transferred to water, but instead is lost through chimneystack. The soot layer acts as a heat insulator for tubes and shells of furnace. The heat is unable to reach water.

This not only causes boiler efficiency to be lowered, but a more serious problem can also occur. The soot can catch fire!

A soot fire can be detrimental to strength of boiler because it can cause serious localized hotspots to occur at tubes. These localized hotspots can even reach temperatures that weaken materials of tubes.

Soot blowers are installed to blow away these soot deposits. Steam is normally used as a medium for blowing away soot.

The operation of soot blowers goes like this:

Where does all heat go?

All these heat has to be removed. If you are not near sea, you have to use cooling towers to cool down your warm water.

Cooling towers make use of air currents to cool warm water. However, a basic rule has to be made when you want to extract heat from any object, including water. Heat has to be taken from a higher temperature source to a lower temperature medium.

If air is already warm, it will not be able to cool down warm water. The temperature difference is very important.

Another important point in cooling tower efficiency is how much water is exposed to air. If water is allowed to trickle down, and their contact surface with air is made large, more heat exchange takes place.

Plastic diffusers designed with wavy patterns are inserted at cooling towers to increase contact surfaces of water when it meets with cooling air stream.

There are several shapes of cooling towers, but they operate on same principle.

There are basically 2 types airflow patterns in cooling towers: