OCR Text |
Show petroleum crudes contain high concentrations of vanadium and nickel. Alkali metals are usually present in both coal-derived and petroleum oils as washable inorganic salts. It has been extensively shown that both vanadium and nickel in petroleum appear as porphyrines whereas coal-derived liquids do not contain porphyrines (McGinnis, 1978; Yen, 1981 and 1975). COMBUSTION STUDIES Coal-derived products can potentially be used as boiler, gas turbine and transportation fuels, as well as feedstocks for chemical industry. However, due to their complex chemical nature, a large portion of coal-derived liquids are expected to be burned in stationary boilers and gas-turbines (Seapan and Crynes, 1983). In combustion processes, trace elements of these liquids will be converted to oxidized compounds and salts, appearing in the combustion gases as vapors and fine aerosol particles. Depositon of these metallic compounds on the internals of turbines and boilers can have detrimental effects on their use. Various industrial, government and academic research organizations, recognizing the present problems with the use of petroleum residual fuels and anticipating future problems in the utilization of coal-derived liquids, have taken the initiative to conduct research programs on the role of trace elements in combustion processes. Experimental studies on the deposition characteristics of trace metals from the combustion of coal-derived liquids and other fuels have been conducted in laboratory test facilities as well as in subscale and 1.5.10 |