Abstract: Method and apparatus for using biofuel or waste material or both for energy production. The biofuel or the waste material is gasified in a fluidized bed gasifier (10), preferably a circulating fluidized bed gasifier. The gas produced in the gasifier is introduced into a boiler (12) equipped with fossil fuel burners (28, 28'28"), typically burners for pulverized coal. The gas is introduced at a level above the burners. Ash from the boiler may be used to form the bed of the gasifier. For control of NO.sub.x, the gas is burned in the upper part of the boiler at a low temperature level of 800.degree.-1050.degree. C. (1472.degree.-1922.degree. F.), preferably 850.degree.-900.degree. C. (1562.degree.-1652.degree. F.), and with a small excess air content of about 5-10 percent. In a second embodiment, the raw gas may be cleaned of harmful or noxious components, and cooled if desired, between the gasifier and the boiler in an additional circulating fluidized bed reactor (152) having a bed of coal ash.

Abstract: A rapping hammer system adapted for periodically rapping and cleaning tubes of a heat exchanger unit to remove undesired deposits from outside the tubes. A plurality of rapping hammers are each pivotably attached to a radial arm extending outwardly from and spaced apart along a rotatable shaft. A spring device is attached to each radial arm and arranged to contact the rapping hammer with sufficient force so as to substantially restrain repeated striking movements of the rapping hammer against an impact stem of the heat exchange unit following an initial impact of the hammer. A method is also disclosed for operating the rapping hammer system for periodically rapping and cleaning the outside surface of heat exchanger tubes such as boiler tubes of accumulated ash and soot deposits.

Abstract: An improvement to a known process in which C.sub.8 aromatic hydrocarbons are treated to recover a desired isomer of xylene, and in particular o-xylene or p-xylene. A step in recovering isomers of xylene typically includes subjecting a mixture of xylenes to fractional distillation and drawing a stream rich in o-xylene from the fractionation column. The current improvement involves the steps of contacting the contents of the fractionation column with an isomerization catalyst, thereby isomerizing C.sub.8 aromatic hydrocarbons in the fractionation column toward equilibrium and consequently enhancing the effectiveness of the fractional distillation in the recovery of the desired xylene isomer. The process can be carried out in the xylene splitter of existing apparatus by making appropriate modifications thereto. It also can be carried out in newly-designed and fabricated apparatus. Embodiments are disclosed for favoring the production either of o-xylene or p-xylene.

Abstract: A process for producing mechanical power utilizing compressed and humidified hot air and a fuel, which are mixed together and combusted and the resulting hot combustion gas is expanded through a gas turbine. The air is initially compressed and intercooled against a water stream, and then further compressed and passed directly to a heat recovery unit where it is humidified using the water from the compressed air intercooling step. The compressed humidified air is further heated against hot turbine exhaust gas and combined with a fuel in a combustor, and the resulting hot combustion gas is expanded through a gas turbine to produce mechanical power needed for driving the air compression. The hot turbine exhaust gas is cooled countercurrently against the compressed humidified air stream and against the water stream, and then discharged to the atmosphere.

Abstract: A fluidized bed steam generating system in which a duct is disposed between a furnace outlet and a separator inlet. The duct is formed by first and second wall panels which are comprised of a plurality of parallel tubes extending perpendicular to the direction of the flow of the combustion gases. The tubes comprising the wall panels are bent and welded to a fin extending from corresponding portions of adjacent tubes to form a gas tight structure. The ends of the tubes are connected in fluid flow communication with first and second headers which enables cooling fluid to flow through the tubes for recovering heat from the combustion gases as they flow from the furnace into the separator.