Andritz Oy

Andritz-ahlstrom Oy

Esa Vakkilainen

Kari Saviharju

Jorma Simonen

Liisa Simonen

Erkki J Kiiskila

Esko Mattelm&auml;ki

Pentti Piilonen

Antti Hyt&ouml;nen

Pia Kilpinen

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 at one or several levels of the furnace. A plurality of air ports are located at several horizontal levels for introducing air into the furnace from an air supply. In the arrangement for the secondary air flows, 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 and the air ports from each of the two levels are located so that the air jets are introduced in an interlaced pattern having an even number of jets on one opposite wall and an uneven number of jets on the other opposite wall. The air jets of said at least two air levels are located substantially one above each other in substantially vertical rows.

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

The present invention relates to an arrangement for introducing black liquor into a furnace of a recovery boiler, said arrangement comprising an elongated tube having an interior surface and an exterior surface, through which tube the black liquor being fed into the furnace is supplied, whereby the black liquor is taken into contact with said interior surface prior to being sprayed into the furnace. The interior surface of said elongated tube is provided with heat transfer elements and surfaces, such as fins or grooves. The heat transfer element or surface increases the heat conductivity between the tube and the black liquor above the conductivity achieved with a normal tube passage.

Arrangement for feeding black liquor into a recovery boiler

A method of removing nitrogen oxides from flue gases of a cellulose pulp mill recovery boiler does so in a cost effective and environmentally friendly manner. In the heat recovery section of the recovery boiler, a peroxide solution (e.g. a water solution containing about 1-35% hydrogen peroxide) is brought into contact with (e.g. sprayed into) the flue gases in the heat recovery section, so that the flue gases and the peroxide remain in contact between about 0.5-5 (preferably between about 1-2) seconds. The majority (e.g. about 60-90%) of the nitrogen oxides are converted to nitrogen dioxide. The temperature of the flue gases at the time of contact with the peroxide solution is between about 300-800.degree. (preferably 400-600.degree.) C. The nitrogen dioxide is removed by scrubbing the flue gases, downstream of the recovery boiler, with an alkaline liquid (e.g. a liquid otherwise used in the pulp mill having a pH of greater than 9) to convert the majority of the nitrogen dioxides into nitrate. The nitrate may be used as a nutrient in a biological effluent treatment plant within the pulp mill.

Method of removing nitrogen oxides from recovery boiler flue gases

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Helsinki, Finland

Esa Vakkilainen