摘要:
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.
摘要:
A gas temperature control system for maintaining a desired economizer outlet gas temperature across a range of boiler loads comprises a plurality of tubular configurations having surfaces that are in contact with the flue gas. Each tubular configuration, preferably, comprises a plurality of serpentine or stringer tubes arranged horizontally or vertically back and forth within the economizer, and each tubular configuration having a separate feedwater inlet. Heat transfer from the flue gas is accomplished by controlling the feedwater flow rates through the tubular configurations. In a temperature control system having two tubular configurations, the overall heat transfer capacity of the economizer may be reduced to maintain the desired economizer outlet gas temperature during low boiler loads by reducing feedwater flow through one tubular configuration and by overflowing the other tubular configuration, such that total flow of feedwater through the economizer is maintained substantially constant.
摘要:
A heat exchanger having an arrangement of heat transfer surfaces and a pair of vertical steam/water separators structurally interconnected to one another to provide an integral support structure for the heat exchanger. The structural interconnection includes upper and lower structural members extending between the pair of vertical steam/water separators. The upper and lower structural members include headers, and an arrangement of heating surface which extends between and is fluidically connected to the headers. A structural support framework surrounds the heat exchanger for bottom support thereof, the framework providing structural support and rigidity for the heat exchanger and a means by which the heat exchanger can be picked up and lifted for placement at a desired location.
摘要:
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.
摘要:
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.
摘要:
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. The upper header of the upflow module is also connected to the steam drum through one or more risers for completing the circuit.
摘要:
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. Using a widened tangential inlet that extends the axial length of the conical portion of the separator, the disclosed separator has an inlet which is increased in width by approximately 16% with no derogation in steaming capacity but with substantially less pressure drop. The inlet design of this separator does not increase the overall length of the separator allowing for its use in smaller diameter steam drums that would be unable to currently utilize conventional separators.
摘要:
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. Apertures may be provided on opposed lateral sides of the air foils for introducing a gas flow into the flue gas passing across the air foils. Ammonia flow to each injection pipe may be individually controlled.
摘要:
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.
摘要:
An apparatus and method for mixing gas streams of different temperatures and/or compositions contemplates that at least one of the streams contains particle. The apparatus includes a main duct for the first gas stream and a plurality of duct assemblies extending in the main duct generally transversely to the first gas stream. Each assembly has plural inlets and outlets for receiving and discharging separate parts of the second gas stream, moving initially generally transverse to the first stream. The assemblies each have plural secondary ducts of mutually different lengths from inlet to outlet, the outlets being spaced from each other across the main duct for distributing the parts of the second gas stream into the first gas stream. A gas flow deflector is connected to each duct assembly for temporarily deflecting the first gas stream before it is combined with the parts of the second gas stream.