Abstract: 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.

Abstract: 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.

Abstract: 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.

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.

Abstract: The invention relates to a method and apparatus for use in the pulp industry for improving the safety of a spent liquor recovery boiler, such as a soda recovery boiler. The boiler comprises, for recovering chemical and energy, a furnace cooled by water tubes and connected to the water/steam circulation system of the boiler, the cooling of the bottom of the furnace being provided by a separate cooling circulation. The separately cooled lower section of the furnace is provided by separating the bottom or the bottom and part of the furnace walls from the boiler water circulation system. This separated section is supplied with a cooling fluid of its own which may be a gas (e.g. air or inert gas) or a liquid (e.g. molten zinc) which does not cause an explosion of it contacts the melt of the furnace.