Combustion development activities, direct

Pacific Northwest Laboratory (PNL) and Lawrence Berkeley Laboratory (LBL) have been selected to provide program management services to the Biomass Energy Systems Program. PNL is responsible for the technical management of development activities directed toward the thermochemical conversion of biomass feedstocks by direct combustion, gasification and indirect liquefaction via synthesis gas. LBL is responsible for the technical management of development activities on the direct liquefaction of biomass feedstocks. 

Figure 1. Direct combustion development activities (near term)...

Transition metal oxides represent a prominent class of partial oxidation catalysts [1-3]. Nevertheless, materials belonging to this class are also active in catalytic combustion. Total oxidation processes for environmental protection are mostly carried out industriaUy on the much more expensive noble metal-based catalysts [4]. Total oxidation is directly related to partial oxidation, athough opposes to it. Thus, investigations on the mechanism of catalytic combustion by transition metal oxides can be useful both to avoid it in partial oxidation and to develop new cheaper materials for catalytic combustion processes. However, although some aspects of the selective oxidation mechanisms appear to be rather established, like the involvement of lattice catalyst oxygen (nucleophilic oxygen) in Mars-van Krevelen type redox cycles [5], others are still uncompletely clarified. Even less is known on the mechanism of total oxidation over transition metal oxides [1-4,6]. 

Unlike the known approaches we develop the use of water- fuel emulsions with the soluble in water catalytic non- corroding additions and ultrasonic mixing by the sharp superheated steam for reduction of the oxides of nitrogen and soot emission in the combustion engines. Our know how is also the use of the electro-activated water for emulgation. The first results testily the technical and economic expedience of the chosen direction. 

In the past few years there still have been some research efforts focused on Mg NiH. The Akiyama s group in Japan [20-22] has developed a hydriding combustion synthesis technique for the direct fabrication of Mg NiH. The results showed that the product of Mg NiH from the hydriding combustion synthesis absorbed the maximum (3.4-3.6 wt%) near the theoretical value just after synthesis without any activation process. 

Uncontrolled open fires in tyre dumps may burn for several months (e.g., Rhinehard tyre fire in Winchester, Virginia), generating many hazardous products of incomplete combustion, which are released directly into the atmosphere (EPA 1997). Owing to safety concerns and other factors (e.g., meteorological conditions, fire-fighting activities), it is difficult to collect air samples from the smoke plumes of these fires. The available field data revealed potentially hazardous levels of several PAHs and CO, as well as relatively high concentrations of Pb and Zn in such plumes (Ohio Air Quality Development Authority 1991 EPA 1997). 

Procedures for the determination of 11 elements in coal—Sb, As, Br, Cd, Cs, Ga, Hg, Rb, Se, U, and Zn—by neutron activation analysis with radiochemical separation are summarized. Separation techniques include direct combustion, distillation, precipitation, ion exchange, and solvent extraction. The evaluation of the radiochemical neutron activation analysis for the determination of mercury in coal used by the Bureau of Mines in its mercury round-robin program is discussed. Neutron activation analysis has played an important role in recent programs to evaluate and test analysis methods and to develop standards for trace elements in coal carried out by the National Bureau of Standards and the Environmental Protection Agency. 

These types of materials will probably play an important role in the further development of combustion catalysts, especially if their activity can be improved. Moreover, they can be extruded to give active monoliths directly. This, however, still generates problems with respect to mechanical strength and thermal shock properties due to the relatively high thermal expansion coefficient [64]. 

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