Abstract: A method for supplying a gaseous medium to a fluidized bed boiler through several pipes of a pipe grate. An active area of the grate is adjusted with a pipe-specific control included in at least some of the pipes of the pipe grate. A supply of gaseous medium to the pipe grate takes place in the active area. The active area of the grate is reduced by forming at least one inactive bed area that is out of use.

Abstract: A method of reducing NOX compounds in the odor gases of a recovery boiler. In the method, ammonia in the odor gases is separated before the odor gases are combusted, the ammonia being then introduced into a recovery boiler at the pulp mill or in a separate catalyzer, where the ammonia reacts with nitrogen oxide forming water and molecular nitrogen.

Abstract: A fluidized bed material including mineral particles of a gabbro class or darker rock type. The rock type includes several minerals and having a quartz content of 5 wt-% or less. The particles are made by comminuting a gabbro class or darker rock type. A fluidized bed process including performing a reaction or a processing of a material in a fludized bed reaction in connection with the fluidization of a fluidized bed material, wherein the fludization bed material includes particles of the gabbro class or darker rock type.

Abstract: Arrangement in a soda recovery boiler, comprising normal melt chutes (6) for removing molten salt from the recovery boiler (1). The recovery boiler (1) comprises an outlet (8), mounted in the wall of the recovery boiler such that it is situated lower down than the normal melt chutes (6), in which case the molten salt can be removed from the bottom of the recovery boiler substantially through the outlet (8), when the recovery boiler (1) is emptied for maintenance or the like.

Abstract: A process chamber is placed in connection with a circulating fluidized bed reactor for utilizing internal or external circulation of solid material or both in heat transfer purposes. Said process chamber is located inside the furnace of the circulating fluidized bed reactor adjacent to at least one of the furnace walls. The interior of said process chamber is provided with heat exchanger means for heat transfer from the solid material to heat transfer medium inside the heat exchanger means. The process chamber comprises a top closed barrier wall forming the roof of the process chamber, wherein the inlet of the solid material into the process chamber is arranged to the lower part of the wall of the process chamber and the outlet of the solid material out of the process chamber is arranged to the upper part of the wall of the process chamber.

Abstract: A method and an arrangement for supplying air to a fluidized bed boiler are disclosed. In the method, the air is supplied from all comers of the fluidized bed boiler substantially parallel to two opposite walls and from the middle of said walls toward the center of the fluidized bed boiler whereby the air flows cause the formation of four vortexes in the fluidized bed boiler. The arrangement comprises nozzles that blow air jets towards each other parallel to the opposite walls of the fluidized bed boiler and nozzles in the middle of the walls arranged to blow air toward the center of the fluidized bed boiler.

Abstract: In a recovery boiler for burning spent liquor of a pulp mill, a combustion chamber has heat transfer walls formed of tubes, at least one vertical heat transfer surface formed of tubes, and superheaters in an upper part of the combustion chamber for recovering heat generated by combustion and for cooling flue gases. The at least one vertical heat transfer surface divides the combustion chamber in a transverse direction into two combustion spaces.

Abstract: A method for upgrading a boiler is provided. When operating at a first capacity, the boiler is used such that an open space is kept in radiation communication with a firebox. The open space is also kept as empty. A first set of water circulation tubes are connected to the boiler cylinder in connection with the ascending tubes. When the boiler is operated at a second capacity, which is higher than the first capacity, at least one additional part is arranged in the open space to expand the basic super heater arrangement. Additionally, or alternatively at the second capacity, a second set of water circulation tubes may be connected to the boiler cylinder in connection with the ascending tubes. The second set of water circulation tube has a capacity exceeding that of the first set of water circulation tubes.

Abstract: A method and arrangement for increasing evaporation capacity in a multi-stage evaporation plant of spent liquor of a pulp mill. The method includes increasing the pressure of vapor discharged from an evaporation stage by a separate booster, and supplying the vapor having increased pressure to the following evaporation stage. In the arrangement the booster (A-E) is provided in a conduit through which vapor is supplied from one evaporation stage onwards for increasing the pressure of the vapor conducted in the conduit.

Abstract: A method and an arrangement for reducing emissions of nitrogen oxides in a combustion apparatus provided with a tubular furnace. The method comprises burning odor gases at first sub-stoichiometrically, and subsequently supplying additional air to the furnace (3) in the transverse direction thereof in such a manner that the final air ratio is over 1. The arrangement comprises an additional air duct (7) which extends to the furnace of the boiler and from which additional air is supplied to the furnace (3) in the transverse direction of the furnace (3).

Abstract: A method and an arrangement for supplying air to a recovery boiler. In the method, the air is supplied to the recovery boiler at at least one air supply level so that four vortices are formed therein, the vortices spinning, in pairs, in opposite directions to one another so that any two adjacent vortices always spin in opposite directions to one another. The arrangement comprises nozzles that are arranged to blow air so that four vortices are formed in the recovery boiler, any two adjacent vortices always spinning in opposite directions to one another.

Abstract: A grate assembly for a fluidized bed boiler is provided. A number of parallel sparge pipes extending substantially in the horizontal direction and are provided with devices for supplying fluidizing air from within sparge pipes into a combustion chamber located above the grate assembly. The discharge of coarse material is effected through an aperture system between the sparge pipes into a receiver unit fitted below the grate assembly. At least some of the sparge pipes are provided with a cool medium circulation, wherein at least a part of the cool medium circulation is placed in the sparge pipes at the upper edges thereof, to extend so that it provides a limit to the edge of the aperture system in the upper part of the sparge pipe in the longitudinal direction of the sparge pipe. Devices for supplying fluidizing air comprise a tubular supply channel that is directed from the upper surface of the sparge pipe. The supply channel is provided with air nozzle apertures at its upper part.

Abstract: Method of reducing corrosion in a power boiler of a pulp mill using biofuel and suspended matter obtained from the waste water treatment of the mill. In the method flue gases obtained from a waste heat boiler are fed into the power boiler, causing the sulfur dioxide contained in them to react with the alkali chlorides in the boiler and the chlorine to form hydrogen chloride.

Abstract: A method for controlling combustion air in a boiler plant, where combustion air is supplied into a boiler located in a boiler building, comprises the steps of determining a ratio of air flow inside the building to air flow outside the building on the basis of at least the temperature of the outside air and of a load of the boiler; taking a first air flow from inside of the building in accordance with the ratio; taking a second air flow from outside the building in accordance with the ratio; the second air flow being at a certain temperature; and supplying a combined combustion air flow including the first and second air flows, in accordance with the ratio, to the boiler. Also an apparatus is provided for controlling combustion in boiler building permitting it to achieve the above steps.