A metal recuperator is described as having an exterior casing with a replaceable inner housing which forms with the casing a pair of separated fluid passageways through which two fluids, at different temperatures, are circulated into heat exchanging relationship. Special seals are provided to allow relative movement between the casing and the housing while sealing the passageways from each other and the ambient atmosphere.
A dirty water heat exchanger keeps solids from settling out while passing through the heat exchanger and includes a cylindrical furnace duct, connected at a first end to a conventional burner, having a spiral liquid heating duct along which the dirty water passes from its first end to its second end. The second end of the furnace duct is open. An exhaust tube surrounds the furnace duct and provides an annular exhaust gap for the hot gases to flow back over the outer surface of the spiral liquid heating duct. The outer end of the exhaust tube is closed to redirect hot gases into the exhaust gap. Spiral flighting along the exhaust gap spirals the exhaust gas to keep the hot gases collecting along the top of the heat exchanger. The gases pass out of the exhaust gap through a flume at the first exhaust tube end. The furnace duct and the exhaust tube are connected together at at most one axial position to accommodate different amounts of axial expansion. The heat exchanger is supported by an expansion mount at the second end of the exhaust tube and by a stationary mount at the first end of the furnace tube.
A heating system comprising a firebox defining a combustion chamber that is substantially sealed from the atmosphere. The system includes a flue for conducting combustion gases from the combustion chamber. A first duct surrounds the flue and defines an inner passageway with respect thereto. A second duct surrounds the first duct and defines an outer passageway. An inlet means is provided for introducing ambient air into the outer passageway. The air in the outer passageway is drawn through the inner passageway by a negative pressure in the combustion chamber. The ambient air in the inner and outer passageways is heated by heat transmitted from the flue. This heated ambient air is then introduced in the combustion chamber to improve the efficiency of combustion.
5116416 - Boron-treated hard metal - Owned by Vermont American Corporation (Louisville, KY) [*] Notice:The portion of the term of this patent subsequent to October 9, 2007 has been disclaimed.
A hard, relatively non-brittle, cemented carbide body is made by sintering pressed grade carbide powders in the presence of a boron-containing material such as boron nitride. During sintering, appreciable quantities of boron migrate or diffuse into the body to become incorporated throughout the microstructure of the carbide resulting in the formation of a third quarternary phase comprised of tungsten, nickel, boron and carbon.
