Methods and apparatus for reducing the content of nitrogen oxides in the flue gases produced by the combustion of fuel gas and combustion air introduced into a burner connected to a furnace are provided. The methods basically comprise the steps of conducting the combustion air to the burner, providing a chamber outside of the burner and furnace for mixing flue gases from the furnace with the fuel gas, discharging the fuel gas in the form of a fuel jet into the mixing chamber so that flue gases from the furnace are drawn into the chamber and mixed with and dilute the fuel gas therein and conducting the resulting mixture of flue gases and fuel gas to the burner wherein the mixture is combined with the combustion air and burned in the furnace.

Fuel dilution methods and apparatus for NOx reduction

A compact and portable liquid concentrator includes a gas inlet, a gas exit and a flow corridor connecting the gas inlet and the gas exit, wherein the flow corridor includes a narrowed portion that accelerates the gas through the flow corridor. A liquid inlet injects liquid into the gas stream at a point prior to the narrowed portion so that the gas-liquid mixture is thoroughly mixed within the flow corridor, causing a portion of the liquid to be evaporated. A demister or fluid scrubber downstream of the narrowed portion removes entrained liquid droplets from the gas stream and re-circulates the removed liquid to the liquid inlet through a re-circulating circuit. Fresh liquid to be concentrated is also introduced into the re-circulating circuit at a rate sufficient to offset the amount of liquid evaporated in the flow corridor.

Compact wastewater concentrator using waste heat

An atmospheric gas burner assembly producing relatively low oxides of nitrogen (NO x ) emissions comprising a gas-air feed tube communicating with a burner chamber portion provided with an apertured inner burner distribution plate member having a multiplicity of relatively large size outlet apertures for distributing the gas-air mixture outwardly from the burner chamber portion, an intermediate burner port plate member overlying the apertured distribution plate member in spaced relation thereto and provided with a multiplicity of relatively small size burner port outlets for issuing outwardly therefrom small gas-air streams which combust to form a low temperature, low flame front profile over the outer surface of the burner port plate member, and an outer screen mantle member of woven stainless steel wire cloth of fine mesh overlying the burner port plate member is closely spaced relation thereto and positioned within the tip ends of the flame front issuing from the burner port plate member to become heated to an infrared radiant heat emitting condition. A turbulator member is positioned within the venturi tube to create turbulence of the fuel-air mixture passing therethrough to minimize resonance thereof during burner operation.

Atmospheric gas burner assembly

A hybrid heating apparatus heats potable water with waste heat from heat recovery units and insolation from solar collectors. A single circulation pump circulates fluid between at least one heat exchanger and each of the heat recovery units and preferably the solar collector. A single controller receives sensor readings from the heat recovery units and the solar collector units and receives a demand to heat the potable water. To satisfy the demand, the controller determines the extent to which the demand may be satisfied from heat available from the heat recovery units and the solar collector units and sends command signals both to the circulating pump to circulate the fluid and to appropriate ones of valves at connections to those heat recovery units and solar collector units to allow fluid to circulate to be heated to flow to the heat exchanger for effecting heat exchange to heat the potable water.

Hybrid water heating system

There is disclosed a gas-fired water heater/boiler apparatus with a unique burner assembly that provides high levels of BTU/hour input making it suitable for commercial installations. The gas burner includes a pair of superimposed tubes, each having evenly distributed perforations of a different uniform size, that are rolled flush together and provide a thick walled burner with greatly increased strength and resistance to premature failure while furnishing an optimum flame pattern. The gas burner projects into the interior of a vertical, cylindrical array of finned heat enchanger tubes through which the fluid to be heated is circulated. The water heater/boiler apparatus is compact and thermally insulated by a ressurized forehearth and may be installed on combustible floors or in closets with zero clearance.

Gas water heater/boiler

In a water heating system, vapor in the products of combustion gases is condensed in a secondary heat exchanger positioned in a housing with the primary heat exchanger and combustion chamber. The two heat exchangers are coaxial coils with the secondary coil positioned below the primary. Gases flow radially through the primary coil and then axially through the secondary coil at an increased velocity. The gases are then used to pre-heat a gas/air mixture in a third heat exchanger within the secondary heat exchanger. The pre-heated gas/air mixture is burned in a burner within the primary heat exchanger and the gas products are drawn through the exchangers by a blower. A water storage tank is designed to enhance stratification of hot water over cooler water. The cooler water is used to condense vapor in the secondary heat exchanger.

Combustion product condensing water heater.

A high efficiency gas fired residential water heater includes an insulated, plastic-lined storage tank. The water in the tank is heated by an external heat exchanger which defines a water-walled combustion chamber. The fuel gas and combustion air burned in the chamber are premixed to a near stoichiometric mixture without the use of a blower. Under the force of line pressure or less, the fuel gas is accelerated into an aspirator/mixer which premixes an amount of air sufficient for complete combustion of the fuel gas. The water-walled combustion chamber is particularly suited for substantial recovery of the heat of a pilot flame. The pilot products of combustion heat water at the upper end of the combustion chamber without causing significant convective flow throughout the heat exchanger.

High efficiency water heating system

A heat recovery system (including associated methods, apparatus and controls for implementing such a system) integrated in a hot water heating system that is combinable with an air conditioning loop containing hot gas wherein the hot water system selectively utilizes heat recovered from the hot gas to produce and store hot water at a preselected temperature level requiring the use of only a single water storage tank. According to one aspect of the invention, hot gas is taken from the air conditioning loop and placed directly into a heat exchanger coil immersed in the water storage tank for selective use therein to produce hot water. According to a further aspect of the invention, a control means is provided to monitor and analyze water temperatures at a plurality of locations within the water storage tank; determine the presence of hot gas and its temperature; and, as a function of the set point for the hot water heating system, selectively activate at least one of a plurality of heaters located in the water storage tank. The heaters include a heat exchanger that may be energized by the hot gas when the gas is at a desirable temperature and available for use; and at least one other heating element, such as electrically energizable heating elements.

Andrew D. Vasilakis

Papers

Combustion product condensing water heater.

High efficiency water heating system

Heat recovery system