BOILER INTERNAL FLUE GAS BY-PASS DAMPER FOR FLUE GAS TEMPERATURE CONTROL

摘要

A flue gas passage arrangement (12) for a steam generator which permitsadjustment of the heat transfer effectiveness of a final bank of heatexchanger surface (16) to control a temperature of the flue gas flowingthrough and exiting from the flue gas passage and conveyed to a downstream NOXreduction device (36) having a minimum operating temperature. The NOX deviceis advantageously an SCR (36). Economizer heating surface is located withinthe flue gas passage, and a baffle plate (30) extends through the flue gaspassage and creates two flue gas paths (26, 28) there through. The economizerheating surface may be a single, common bank having a section located in bothgas paths, or in only one gas path. Alternatively, two separate banks ofeconomizer heating surface may be employed. A variable position damper (32) isprovided in one gas path, either below or above the section.