SOLID FUELS

Solid fuels (including coal, wood, and solid waste) present some of the same handling difficulties. Problems occur unless a free-flowing, continuous supply of fuel that is properly sized for the specific type of combustion equipment is provided. The problems include sizing, shredding or pulverizing, consistency of moisture content, freezing or lumping, dusting, fires in storage due to spontaneous combustion, and fires in the feed or ash handling systems.

Most problems can be minimized or eliminated through proper selection of fuel handling equipment. Specific types of equipment for handling, storage, and preparation depend on the characteristics of the solid fuel used.

Because the proper equipment is not always available, fuel additives or aids have been used in the attempt to minimize problems. These additives include grinding aids, moisture improvers, dusting aids, freezing inhibitors, and catalysts to minimize combustibles in ash and fly ash handling systems.

LIQUID FUELS

Liquid fuels include waste oils, light oils, heavy oils, and other combustible liquids. Because of the problems of liquid residue disposal, an increasing variety of combustible liquids is being considered and tested. Figures 20-1 and 20-2 illustrate key components found in a typical liquid fuel handling system and fuel oil storage system , respectively.

Problems encountered in the handling, storage, and preparation of liquid fuels include water contamination, sludge formation, resistance to flow, biological growths, instability, and corrosive-ness. Generally, these conditions are manifested as excessive strainer plugging, poor flow, increased loading on the fuel pump, heater deposits, fuel line deposits, loss of storage space, burner tip deposits, burner fouling, leakage due to storage tank corrosion, poor atomization, and other combustion problems. Table 20-1 summarizes the nature and cause of problems associated with key liquid fuel handling system components; some of these conditions are illustrated in Figures 20-3 - 20-4 and 20-5 - 20-6.