Abstract: A steam supply passage incorporates a pressure reducing valve and the passage further incorporates a steam ejector downstream of the pressure reducing valve. A suction portion of the steam ejector is connected to a re-evaporation tank for re-evaporating steam condensate via a suction passage. Passage steam of the pressure reducing valve is used as a driving steam for the steam ejector. In operation, re-evaporated steam within the re-evaporation tank is suctioned by the steam ejector to be mixed with the passage steam. The suction passage incorporates a check valve for preventing reverse flow of steam to the re-evaporation tank.

Abstract: A method and apparatus effectively bypasses flue gas through or around selected boiler convection heat transfer tube banks within a new or existing boiler flue. Heat transfer tubes are removed, or omitted in the design of a new boiler flue, forming one or more voids at one or more locations within the tube banks. A bypass flue or conduit is formed within each void, for example using steel plates, along with existing flue walls, or using an integral sleeve. A wall of the bypass flue may include water or steam-cooled tubes. Dampers may be installed at either end of or within the bypass flue to control the amount of flue gas directed through each bypass flue.

Abstract: A flue gas passage arrangement for a steam generator which permits adjustment of the heat transfer effectiveness of a final bank of heat exchanger surface to control a temperature of the flue gas flowing through and exiting from the flue gas passage and conveyed to a downstream NOx reduction device having a minimum operating temperature. The NOx reduction device is advantageously an SCR. Economizer heating surface is located within the flue gas passage, and a baffle plate extends through the flue gas passage and creates two flue gas paths there through. The economizer heating surface may be a single, common bank having a section located in both gas paths, or in only one gas path. Alternatively, two separate banks of economizer heating surface may be employed. A variable position damper is provided in one gas path, either below or above one section.