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.
April 11, 2008
Date of Patent:
October 25, 2011
Babcock & Wilcox Power Generation Group, Inc.
Eric M. Warren, Kevin A. Larson, Thomas A. Laursen, Christopher J. Thompson, Shan A. Shanmugavel
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.