FUEL TREATMENT FUNDAMENTALS (Amtek Research Inc. Canada)

Atmospheric Pollutants

• Pulverized Coal Fired (200 mesh size ~ 75 micron particles)
• Stoker Fired (~20 mm)
• Fluidized Bed Combustion (up to 6 mm) Unburned carbon escapes along with the Fly Ash and Bottom Ash. These are trapped in the ESP but the smoke escapes. Smoke is a mix of partially burned carbon(C, CO) and volatile matter (HC), SO2.

• Uniformity in the coal particle size and smaller particles for pulverized coal boilers
• Sufficient oxygen (air)
• Use of Combustion Catalyst [These are available in Powder and Aqua-metallic form], which lowers the ignition temperature of carbon. It is available in powder and liquid form, which is sprayed on the coal. The liquid additive is more effective as it enters into the body of the coal particle.

Before combustion, fuel oils of all types are atomized. The size of oil droplets varies from 100-500 microns. The droplets burn layer by layer. At the end of combustion, soot and cenosphere -the unburned fuel- exits the combustion system. The smoke consists of soot, cenosphere, CO, PAH, SOx and NOx in liquid fuel, certain components have been found as the primary components to cause smoke and soot problems. Paraffinic (such as LSWR) or asphaltenic structures in the fuel oil and a distribution of various boiling points by the fuel components are known to contribute to particulate problem.

In the case of LSWR, this fuel has a high content of aliphatic hydrocarbons, which give it the waxy character. High molecular weight saturated hydrocarbons burn more slowly. When large molecules are not combusted completely in the flame zone, smoke unburned carbon (soot) and smut (carbon + sulfuric acid) comes out of chimney.

• Heat the Oil and reduce the viscosity for finer atomization
• Homogenize he fuel oil by adding Fuel Oil Homogenizer. The homogenizer makes the heavy fuel molecules smaller and disperses them throughout the storage tank. The oil density becomes uniform. This results in stable burner settings and efficient combustion of fuel oil.
• Use Combustion Catalysts to burn the C, CO and PAH in the combustion zone.