Abstract: A steam generator circulation system is provided and includes a boiler feed pump for forcing water through an economizer, and through the waterwall tubes of an evaporator. A separator receives a mixture of steam and water and sends the steam to a steam utilization unit such as a superheater. A valve is provided below the separator. If the valve is open, the saturated water from the separator is mixed with feedwater and recirculated through the tubes of the evaporator. If the valve is closed, recirculation is terminated. At loads below the critical point, the valve below the separator system would be open and the boiler would operate like a natural circulation drum boiler. At loads above the critical point, the valve below the separator system would be closed resulting in a boiler that operates like a once-through boiler.

Abstract: A dual pressure boiler system has a bottom furnace that operates as a low pressure natural circulation steam generating system and a top furnace that operates as a high pressure natural circulation steam generating system. The low pressure natural circulation steam generating system has a low pressure steam drum, a first pump for providing feed water to the low pressure steam drum, and a low pressure superheater fluidly connected to the low pressure steam drum. The high pressure natural circulation steam generating system has a high pressure steam drum, a second pump for providing feed water to the high pressure steam drum, and a high pressure superheater fluidly connected to the high pressure steam drum.

Abstract: An integrated air foil and ammonia injection grid provides a plurality of air foils across a flue conveying flue gas. Each air foil has a leading curved edge and a tapered, pointed, trailing end. At least one injection pipe is positioned inside each air foil, and has at least one nozzle for injecting ammonia into the flue gas flowing across the air foils. Preferably, plural injection tubes are provided and positioned one behind the other in each air foil, and each injection tube in a given air foil has a length different than a length of the other injection tubes in the same air foil. A longest injection tube in a given air foil is located furthest downstream and proximate the tapered trailing edge and a shortest injection tube in the same air foil is located furthest upstream, remaining injection tubes in the same air foil being progressively shorter the further upstream any injection tube is located.

Abstract: A convection pass enclosure for a boiler comprising a front wall having a gas inlet for receiving gases from the boiler; right and left side walls connected to the front wall; a rear wall having a gas outlet, the rear wall being connected between the right and left side walls; and a roof, at least one of the front wall, right side wall, left side wall and rear side wall having a heat exchanger surface in the form of a horizontal spiral tube assembly.

Abstract: A system for maintaining an optimal flue gas inlet to a boiler mounted SCR assembly in the flue of the boiler is accomplished by mixing the normal inlet feedwater to an economizer of the boiler with near saturation water from downcomers of the boiler to thereby raise the temperature of the flue gas passing across the economizer and raising the SCR inlet to the desired optimal SCR operation temperature.

Abstract: A system for maintaining an optimal flue gas inlet to a boiler mounted SCR assembly in the flue of the boiler is accomplished by mixing the normal inlet feedwater to an economizer of the boiler with near saturation water from downcomers of the boiler to thereby raise the temperature of the flue gas passing across the economizer and raising the SCR inlet to the desired optimal SCR operation temperature.

Abstract: An access door for a boiler or furnace has a water-cooled jacket mounted on a door panel frame for use in high temperature regions of furnaces and boilers. The door is large enough to permit a stretcher to pass through unobstructed. The water-cooled jacket has a series of baffles which direct water in a serpentine path through the jacket. Plant water, as opposed to boiler quality water, may be used to cool the door. A viewing port may be provided in the door as well.

Abstract: A drumless natural circulation boiler system has a furnace enclosure with wall tubes and upper and lower headers connected to respective upper and lower ends of the wall tubes. At least one tangential steam/water separator is connected to a plurality of riser tubes that are also connected to the upper headers. The riser tubes return a steam/water mixture to the separator. Each riser tube is connected to the separator at a tangential nozzle for swirling the steam/water mixture in the separator for separating steam from water in the separator. At least one saturated connecting tube is connected to the separator for conveying steam therefrom. A downcomer is connected to the separator for conveying water from the separator and a plurality of supply tubes are connected between the downcomer and the lower headers. The separator includes a vertically extending cylindrical enclosure and a feedwater conduit is connected to the separator for supplying feedwater to the separator.

Abstract: An arrangement of air foils in a duct bend for channeling an air flow through the duct in a manner which enhances the accuracy of pressure measurements taken at one or more points in the channels formed in the duct between the air foils.

Abstract: A multi-directional after-air port for controlling air flow to a furnace in a staged combustion system has multiple sets of louvers or dampers oriented perpendicular to each other for improved control over combustion air-flow direction.

Abstract: A vertical tube, once-through, sliding pressure steam generator comprises a furnace having an outlet and heat exchanger surfaces made of smooth bore tubes, single-lead ribbed (SLR) tubes, and multiple-lead ribbed (MLR) tubes. All of these tubes are preferably constructed as membrane wall tube panels. The steam generator includes fuel burners for burning fuel and air within the housing, creating low, medium and high heat flux regions within the furnace. Fluid flows through the tubes of the wall panels to provide an efficient heat exchanger. The smooth bore tubes are located at the low heat flux regions, and the SLR and/or MLR tubes are located in the high and medium heat flux regions.

Abstract: A fluid flow circuit for a boiler having a combustion chamber and an exhaust passage. In one embodiment there is provided at least one upflow evaporative generating bank module in the exhaust passage and at least one downflow evaporative generating bank module in the exhaust passage, positioned downstream of the upflow module. One or more upper downcomers are connected to a steam drum and supply water to the lower header of the upflow module and to the upper header of the downflow module. If needed, the convection pass wall enclosures can also be fed by the upper downcomers to their upper inlet headers. One or more lower downcomers may be connected to each lower header of the downflow module (and to the lower outlet headers of the convection pass wall enclosures) for supplying the water to a plurality of furnace circuits which extend along the combustion chamber in the boiler. The opposite end of each furnace circuit is connected to one or more risers which, in turn, are connected to the steam drum.

Abstract: A fluid flow circuit for a boiler having a combustion chamber and an exhaust passage. In one embodiment there is provided at least one upflow evaporative generating bank module in the exhaust passage and at least one downflow evaporative generating bank module in the exhaust passage, positioned downstream of the upflow module. One or more upper downcomers are connected to a steam drum and supply water to the lower header of the upflow module and to the upper header of the downflow module. If needed, the convection pass wall enclosures can also be fed by the upper downcomers to their upper inlet headers. One or more lower downcomers may be connected to each lower header of the downflow module (and to the lower outlet headers of the convection pass wall enclosures) for supplying the water to a plurality of furnace circuits which extend along the combustion chamber in the boiler. The opposite end of each furnace circuit is connected to one or more risers which, in turn, are connected to the steam drum.

Abstract: An apparatus for determining the fluid velocity and direction of flow in a generating bank tube attached to a drum of a boiler provides fluid to a measurement area located within the drum. In one embodiment, static and dynamic pressures of the fluid within the measurement area are determined by a pitot tube assembly located in the measurement area and sent to a pressure measuring device such as a U-tube manometer or a Bourdon gage for a direct pressure reading, or to a pressure transmitter to produce signals for processing by a calculating device. The calculating devices processes the pressure transmitter signals representative of the pressures, uses the energy equation to calculate the fluid velocity based upon these pressures, and transmits same to a display device for reading by an operator. In another embodiment, a flowmeter is used on the measurement area directly and transmits the fluid velocity to a display device.

Abstract: A conical cyclone separator for separating steam from water in a steam/water mixture supplied to a steam drum of a boiler, comprises a conical portion with upper and lower cylindrical portions. Unlike conventional separators which include a tangential inlet extending the axial length of the conical portion of the separator only, the disclosed separator has an inlet which extends by approximately 20% of its length over the lower cylindrical portion of the housing and is vertically elongated over the inlet of conventional separators.

Abstract: A fluid flow circuit for a boiler having a combustion chamber and an exhaust passage. In one embodiment there is provided at least one upflow evaporative generating bank module in the exhaust passage and at least one downflow evaporative generating bank module in the exhaust passage, positioned downstream of the upflow module. One or more upper downcomers are connected to a steam drum and supply water to the lower header of the upflow module and to the upper header of the downflow module. If needed, the convection pass wall enclosures can also be fed by the upper downcomers to their upper inlet headers. One or more lower downcomers may be connected to each lower header of the downflow module (and to the lower outlet headers of the convection pass wall enclosures) for supplying the water to a plurality of furnace circuits which extend along the combustion chamber in the boiler. The opposite end of each furnace circuit is connected to one or more risers which, in turn, are connected to the steam drum.