Abstract: A method for reducing corrosion of a superheater of a steam boiler. The superheater includes a superheater piping. The superheating piping includes a steam pipe where the steam to be superheated is directed. The steam pipe is separated by a protective shell having a surface settling in the flue gas space has a temperature that rises above an upper critical temperature, above which temperature in the flue gas space the compounds from the fuel are substantially in a gaseous form. A superheater of a steam boiler and a circulating fluidized bed boiler.

Abstract: The invention relates to an arrangement in a recovery boiler into which spent liquor to be incinerated and combustion air are supplied, the arrangement comprising superheaters (4a-4d) in the upper part of the recovery boiler for recovering heat, at least one boiler bank (11) located in a flue gas duct part (10a) known as the second pass, immediately after the recovery boiler, and at least one economizer (12a-12b) in a duct part after the second pass in the recovery boiler flue gas duct (10). The invention comprises an economizer (21) located parallel with the boiler bank (11) in the second pass.

Abstract: The invention relates to an arrangement in a recovery boiler, into which spent liquor to be combusted and combustion air are fed, the arrangement comprising superheaters in the upper part of the recovery boiler for recovering heat. Instead of screen tubes the invention is provided with a superheater formed of horizontal elements.

Abstract: A method for removing impurities accumulated in a scrubbing fluid in a flue gas scrubber and effluents from the scrubber. The flue gases are scrubbed with a scrubbing fluid that includes a calcium-containing absorbent. The scrubbing fluid containing gypsum and other impurities and produced in the scrubber is discharged from the scrubber. The gypsum is separated from the scrubbing fluid. To the scrubbing fluid is added an auxiliary agent, by the effect of which the impurities accumulated in the scrubbing fluid are removed with the gypsum and the moisture content of the gypsum to be separated from the scrubbing fluid is increased.

Abstract: In a method for processing flue gases, flue gases from an incineration plant for non-condensable gases of a kraft pulp mill are scrubbed by means of a calcium compound. The calcium compound is lime mud taken from the chemical recirculation of the kraft pulp mill after causticization and before a lime reburning kiln, and it is used in the scrubbing of gas as a substance reacting with sulphur dioxide.

Abstract: A circulating fluidized bed boiler including a furnace, a separator which is connected to the furnace to separate fluidized bed material from a flow leaving the furnace, as well as a return duct between the separator and the furnace to return the separated fluidized bed material into the furnace. The return duct includes a loop seal equipped with a heat exchanger and a supply of fluidizing medium and having an inlet and an outlet, which open into a chamber including the heat exchanger, i.e. a heat exchanger chamber, and are situated at different heights, the outlet being connected through a return conduit to the furnace. The flow cross-section area of the outlet is at an angle to the flow cross-section area of the inlet in such a way that the fluidized bed material is transferred in the heat exchanger chamber in lateral direction with respect to the inlet direction of its inlet flow.

Abstract: A method for improving the operation safety of the smelt spout area of a recovery boiler, which smelt spout area comprises a working area (6), as well as smelt spouts (2) connected to the lower part of the boiler for directing the smelt from the boiler to a dissolving tank (4). In the method the smelt spouts (2) are separated from the working area (6) by a shielding wall (8, 10) arranged movable in relation to the smelt spouts. The invention also relates to a smelt spout area of a recovery boiler.

Abstract: A method and an apparatus for removing carbon dioxide (CO2) from sulphur dioxide containing (SO2) flue gases, wherein the flue gases are washed with washing solution in a scrubber, which comprises at least two washing stages. In the first washing stage the flue gases are washed for removing the sulphur dioxide in the flue gases and after that in the second washing stage for removing carbon dioxide (CO2). Sodium carbonate solution (Na2CO3) is used as washing solution in both the first and the second washing stages.

Abstract: A heat control system of reheating steam of a power plant, in which method the reheating steam (S3) is superheated in a reheater in a first reheating stage and a second reheating stage. The steam (S6) superheated in the first reheating stage is directed via a heat exchanger (22) to the second reheating stage, and the temperature of the steam decreases in the heat exchanger. In addition, the invention relates to a heat control system and a power plant.

Abstract: A boiler plant comprises a fluidized bed boiler having a furnace (1), a flue gas duct (5) exiting the furnace, and a sorting device (8) which is arranged to separate a first fraction from the fly ash entering the flue gas duct, as well as a side duct (9) for leading the first fraction away from the sorting device (8). The boiler plant comprises a separator (10) for separating a first fly ash fraction from the flue gases flowing in the side duct (9). The sorting device (8) is arranged to separate into the side duct (9) the flue gases from a flow entering the flue gas duct (5). The flow in the side duct is more concentrated with respect to the fly ash and has a smaller gas volume than a flow that remains in the flue gas duct (5) after the sorting device (8). As to its hazard classification, the first fraction of fly ash obtained by the separator (10) corresponds to bottom ash.

Abstract: A method for shielding the inner surface above the shield refractory (4) of the furnace wall (3) of a circulating fluidized bed boiler from erosion caused by suspension flows, in which method a shield structure is formed on the inner surface of the boiler wall. At least a first zone (1) and a second zone (2) are formed in the shield structure, the erosion-resistance properties of which zones differ from each other. In addition the invention relates to a circulating fluidized bed boiler, which comprises a corresponding shield structure.

Abstract: The invention relates to a combined fluidized bed and pulverized coal combustion method and system. In the method, fluidizing air (4) is injected into a fluidized bed (2) situated in the bottom portion of the combustion chamber (3). Into the combustion chamber, to above the fluidized bed (2), is fed a mixture of pulverized coal and a carrier gas from a second set of fuel feed means (6) at a mass flow rate which is higher or at least substantially equal to the upper ignition limit of the mixture, and the mixture of the pulverized coal and the carrier gas at least by the fluidizing air (4), and at least a fraction of the fuel fed via the second set of fuel feed means (6) is combusted above the fluidized bed (2).

Abstract: A circulating fluidized bed boiler including a furnace, a separator which is connected to the furnace to separate fluidized bed material from a flow leaving the furnace, as well as a return duct between the separator and the furnace to return the separated fluidized bed material into the furnace. The return duct includes a loop seal equipped with a heat exchanger and a supply of fluidizing medium and having an inlet and an outlet, which open into a chamber including the heat exchanger, i.e. a heat exchanger chamber, and are situated at different heights, the outlet being connected through a return conduit to the furnace . The flow cross-section area of the outlet is at an angle to the flow cross-section area of the inlet in such a way that the fluidized bed material is transferred in the heat exchanger chamber in lateral direction with respect to the inlet direction of its inlet flow.

Abstract: A method for processing flue gas scrubber material flows. The flue gas is scrubbed with a calcium-based absorbent containing washing fluid for absorbing sulphur oxides from the flue gases, and the formed gypsum slurry is directed from the flue gas scrubber to the separator. At the separating point of the separator, gypsum is separated from the washing fluid and the gypsum and washing fluid are taken out of the separator as separate material flows. From the flue gas scrubber the washing fluid is directed to a tank located before the separating point of the separator or after the separating point of the separator, in which tank foam is separated from the washing fluid as its own phase and taken out of the tank.

Abstract: A method and a system for feeding combustion air of a soda recovery boiler to a furnace. The air is fed to the boiler furnace as primary air jets and auxiliary airjets, which are substantially shorter than the primary air jets. At least one primary airjet is placed between two opposite auxiliary air jets.

Abstract: The invention relates to a black liquor gun (4) for feeding black liquor into a recovery boiler (1), comprising a nozzle (11) to be inserted into a furnace (2). Inside the black liquor gun (4) there is a flow guidance element (16), which provides an annular flow channel between the outer wall (14) and the flow guidance element (16).

Abstract: A method for adjusting a supply of gaseous medium to a fluidized bed boiler performing a combustion process and including a pipe grate comprising a plurality of pipes. An active area of the pipe grate is adjusted to form at least one inactive bed area that is out of use by shutting off the supply of gaseous medium to some of the pipes of the pipe grate utilizing pipe-specific control means included in at least some of the pipes of the pipe grate. Cooling medium is conducted through cooling channels located in the pipes in the at least one inactive bed area at least during the combustion process.

Abstract: The invention relates to a black liquor gun (4) for feeding black liquor into a recovery boiler (1), comprising a nozzle (11) to be inserted into a furnace (2). Inside the black liquor gun (4) there is a flow guidance element (16), which provides an annular flow channel between the outer wall (14) and the flow guidance element (16).

Abstract: In a soda recovery boiler, flue gases are led through a so-called economizer (3) to recover heat from flue gases. The flue gases are cooled in the last stage (3b) of the economizer (3) with a circulation water cooler (4) for flue gases, separate from the supply water system of the boiler. The circulation water cooler (4) for flue gases is used for preheating combustion air.