Economizer system

Abstract

An otherwise conventional recovery boiler for burning black liquor (e.g. with a consistency of between about 70-90%) requires less capital investment and takes up less space by constructing the economizers in a particular manner. At least first and second economizers are provided for preheating feed water utilizing flue gas from combustion of the black liquor. The economizers are positioned substantially adjacent each other and connected in such a way that flue gas leaving the first economizer passes substantially directly (i.e. without going through a conventional accessory passage) into the second economizer. The economizer inlets and outlets are substantially at the same level as the adjacent economizer outlets and inlets, or vertically spaced less than about one-third the length of the previous economizer. A boiler bank may be connected between the superheater section of the recovery boiler and the first economizer, and any number of economizers can be utilized. The flue gas flowing through one economizer are turned after exiting so that it flows in a substantially opposite direction while passing through the adjacent economizer.

Dependencies are inferred from the claim text.