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 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.

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 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.

Abstract: A method to produce energy at a pulp mill, including the steps of: combusting pulping process waste liquor in the furnace of a recovery boiler to generate flue gases, recovering the heat from the flue gases by producing saturated and/or partially superheated steam in the recovery boiler, gasifying wood, bark or wood wastes in a gasifier for producing a combustible gas, burning at least part of the combustible gas in a superheating boiler, and superheating the saturated and partially superheated steam in the superheating boiler to produce superheated steam.

Abstract: The invention relates to a method and an arrangement in the production of electric energy in a boiler plant of a pulp mill. Black liquor having a dry solids content of more than 80% and combustion air are fed into a furnace of a recovery boiler for combusting black liquor and recovering chemicals contained therein. The flue gases generated in the combustion are led into an economizer of the recovery boiler, in which economizer the feed water for the boiler is heated, and after the economizer to gas cleaning. The feed water is led from the economizer onto the steam-generating bank at a temperature below the saturation temperature and further into a superheater to produce steam having a pressure of more than 80 bar. The steam is led from the recovery boiler to a steam turbine to produce electricity. The temperature of the feed water being led into the economizer is regulated by means of bleed steam of the turbine so that the flue gases exit the economizer at a temperature of more than 250° C.

Abstract: The invention relates to a method and an arrangement in the production of electric energy in a boiler plant of a pulp mill. Black liquor having a dry solids content of more than 80% and combustion air are fed into a furnace of a recovery boiler for combusting black liquor and recovering chemicals contained therein. The flue gases generated in the combustion are led into an economizer of the recovery boiler, in which economizer the feed water for the boiler is heated, and after the economizer to gas cleaning. The feed water is led from the economizer onto the steam-generating bank at a temperature below the saturation temperature and further into a superheater to produce steam having a pressure of more than 80 bar. The steam is led from the recovery boiler to a steam turbine to produce electricity. The temperature of the feed water being led into the economizer is regulated by means of bleed steam of the turbine so that the flue gases exit the economizer at a temperature of more than 250° C.

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 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.

Abstract: 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.