Boiler Refractory Material

What Is The Purpose Of Refractory Material?

A commercial boiler must be durable in order to handle chemicals, heat and pressure. One component that lends strength to the equipment is the boiler refractory.

The refractory is the heat-resistant material that lines high-temperature furnaces and reactors and other processing units, including commercial boilers. While refractory must be able to stand up to thermal stress, it also must be able to undergo physical wear and corrosion that comes from chemicals in the boiler. Refractory materials can be used to fill gaps and openings in a boiler, or to line parts of the boiler. They can also protect wall tubes that are inside fluidized bed, cyclone-fired or refuse-derived fired boilers.

Boiler refractories are required for heating applications above 1000°F. In general, two types of refractories exist: brick- or fire-shaped, and monolithic.

Materials in a Boiler Refractory

When assembled, many boiler refractories look like construction bricks, but other boiler refractory linings are made from plastics, castables, gunning mixes or ramming mixes—or both of those put together. Typically a boiler refractory comes from a natural or synthetic material—most are non-metallic. They can be comprised of compounds and minerals such as fireclays, bauxite, silicon carbide, zirconia, chromite, alumina, dolomite, or magnesite.

When a refractory is properly made and installed, it can save about 5% to 7% of fuel costs.

Is Your Refractory Causing Problems?

One of the main reasons that commercial boilers are inefficient or shut down can be due to refractory failure. Discovering why a refractory material fails can include many different factors, such as the following:

• It does not match the environment
• It does not align with the fuel being burned
• It may have been stored, mixed, installed, or cured improperly
• It did not match with the environment after fuel was burned

The material may fail due to excessive temperatures, thermal shock, or the boiler. It also may not operate properly if edge is broken or there is a hole in the material. Additionally, something as simple as moisture in the fuel could cause refractory problems.

To find out if the right refractory material is in your boiler, facility managers can calculate the base-to-acid ratio in order to determine the environment that the material was in.