Boiler Combustion & Efficiency

March 31, 2021

The fundamental elements of combustion are fuel, heat, and oxygen. This is important because each of these elements is essential for maintaining the continuous chemical reaction. If any of these diminishes, efficiency will fall until the flame fails.

So, what does this have to do with boilers?

Most commercial boilers rely on combustion for their steam or hot water needs. Like any good fire, these same elements are needed for combustion to exist and sustain. Industrial burners are installed on boilers to properly provide the furnace with the appropriate combustion in order to maintain the process or heating requirements.

When combustion inside the furnace occurs, the burner is responsible for delivering these essential elements. Fuels are generally natural gas, light or heavy fuels, digester gas, or other alternative fuel sources. The flame safeguard or burner management system will regulate the opening and closing of fuel valves to help regulate the fuel demand.

The heat in this case is a spark or ignition source. This could be either an intermittent or continuous pilot. Finally a steady supply of oxygen is required for the combustion process to occur and sustain. Again, take any of these away and the flame will fail.

Within the burner combustion process, each of these elements are equally important. The oxygen is often overlooked but plays a very important role in the boiler room. A burner draws combustion air from the environment in which it is installed. Too little combustion air can result in unburnt fuel left inside the furnace usually resulting in a sooted up fireside.

Within a boiler, the moment the flame changes, the efficiency and heating capability of the flame diminishes rapidly. Maintaining optimum flame is best for reliability and efficiency.

So how do we ensure that we are achieving complete combustion throughout the firing sequence in our boiler rooms? The method for achieving this is usually approached by one of two commonly used burner management designs: 1) a linkage-type system, or 2) a parallel positioning system.

Regardless of the type of system used, these fuel to air ratios need to be set or tuned regularly by using a combustion analyzer to check the components of the flue gases. Daily visual checks of the flame are good practice but they aren’t sufficient in giving a diagnosis of the combustion itself.

Getting the right balance of fuel and air and maintaining it should be at the top of your list in optimizing your boiler rooms.

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