In a showroom floor, a combustor equipped stove may look like any other wood stove. But once a combustor -equipped stove is installed and ready for use, there are certain slight differences an operator must keep in mind. These differences involved in obtaining conditions favorable to combustor performance, such as:

- Reaching proper catalytic operational temperatures, commonly known as light-off;

- Maintaining the conditions that support catalytic burning;

- Proper bypass positioning.

What's needed to create a functional catalytic system?

Because a wood stove combustor is an afterburner of sorts, three elements are needed to support combustion: fuel, oxygen and heat. The fuel used by the catalytic combustor is the byproduct of incomplete combustion of the wood. Most people call this byproduct "smoke;" technically, however, this fuel usually exists in the form of unburned hydrocarbons (HC) and carbon monoxide (CO).

The oxygen required to support the combustion process can come from two sources. It can be the excess oxygen not consumed by the primary burn. Or it can be secondary oxygen delivered expressly for use by the combustor. The heat needed to initiate combustion is approximately 500° to 600° F (260° to 320° C). This is half the temperature normally required without the use of a catalyst. Once combustion starts, the inlet firebox temperature isn't important. As long as fuel and oxygen (the proper amount of oxygen) are delivered to the combustor, it will generate enough of its own heat to maintain combustion. In actual operation, an internal firebox temperature of at least 250° to 400° F (120° to 210° C) is needed to continue the paralysis of the wood. These temperatures are sufficient to maintain a continued catalytic burn within the combustor. (Remember, these are gas temperatures and not firebox surface temperatures.)

The Burning Cycle
Wood smoke is comprised of many compounds, some more easily ignited and burned than others. It is the simpler compounds that burn first in the presence of a catalyst. As the simple compounds burn, they release significant amounts of heat. This heat assists in the volatilization and breakdown of the more complex compounds into simpler materials. This burning-breakdown-burning cycle continues while the wood smoke and oxygen travel through the combustor.

The burning-breakdown-burning cycle is maintained throughout the full length of the combustor. Theoretically, 100 percent combustion efficiency is possible if the proper mixture of fuel and oxygen were to be exposed to a very long combustor. In such as the Oretical arrangement, all of the hydrocarbons and carbon monoxide would be converted to carbon dioxide and water. But as will be discussed later, this is neither practical nor possible. The temperature rise from firebox inlet gas temperature to combustor internal gas temperature is a measure of a combustor's activity. Figure 3 charts this activity. The firebox of a wood stove was loaded at Point A. The lower line indicates firebox gas temperature and the top line indicates the temperature of the gas within the combustor. During the pyrolization phase of wood burning, the combustor actively burns -the wood gases that cause creosote. At Point B volatiles have been exhausted and pyrolization has been completed. The temperature rise from Point B to Point C is mainly a result of the combustor burning carbon monoxide given off during the charcoal phase of the wood burning cycle. At Point C the stove is loaded once again and the cycle is repeated.

To learn more please select from the menu below:

Operating Parameters

Achieving Catalytic Light-Off

Recomended Fules

Draft Controls

Temperature Monitors

For more information contact us!