Ahlstrom Machinery Oy

A. Ahlstrom Corporation

Andritz Oy

Raimo Paju

Jukka Savolainen

Kari Saviharju

Jorma Simonen

Markku Tanttu

Esa Vihavainen

An arrangement is disclosed for supplying an air jet form to the furnace of a recovery boiler, where the furnace has a front wall, a rear wall and side walls. Black liquor spraying devices are disposed on the furnace walls on one or several levels of the furnace. A plurality of air ports are located at several horizontal elevations for introducing air into the furnace from an air supply. In the arrangement for the secondary air flows, at least two horizontal air levels at different elevations are arranged above the lower primary levels and below the black liquor sprayer. Secondary air is supplied from two opposite walls. The secondary air ports on each of said first and second horizontal elevations comprise air ports for each horizontal elevation that project a pattern of large air jets into the furnace from said opposite walls and said secondary air ports further comprise a plurality of secondary air ports on at least one of the elevations that project smaller air jets into the furnace.

Combustion air system for recovery boilers, burning spent liquors from pulping processes

The intensity of explosions as a result of hot (750-820 degrees C.) smelt from a pulp mill recovery boiler impacting cool (70-100 degrees C.) liquid in a dissolving tank is minimized by more effectively disrupting the flow of smelt from a spout free end tip into the tank. First and second nozzles which issue jets of disrupting fluid (such as steam or green liquor) are positioned on opposite sides of the center line of the spout, and are positioned and spaced from the spout tip and each other so that the jet emanating from at least one of the nozzles always intersects the flow of smelt from the spout even though the smelt flow path varies during normal operation of the recovery boiler. The first and second nozzles are preferably each spaced from the spout free end tip a distance of between about 300-700 mm, but different by at least 50 mm from the other nozzle, and are positioned downwardly and obliquely at an angle to the vertical so that the jets move downwardly and obliquely making an angle of between about 20-40 degrees with respect to the vertical. Other nozzles--e. g. in front of the smelt flow--can also be provided within a hood covering the spout area.

Disrupting the flow from the smelt spout of a recovery boiler

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.

Economizer system

Method and apparatus for improving the safety of a spent liquor recovery

Growing community of inventors

Varkaus, Finland

Raimo Paju