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: The invention relates to a method of adjusting the sulphur balance of a sulphate cellulose plant, in which method black liquor is concentrated and heat treated by keeping it at a temperature higher than the cooking temperature for a certain time period to separate the sulphur compounds contained in the black liquor as gaseous sulphur compounds therefrom in the last evaporation stage of a series of evaporation stages.

Abstract: Process for removing nitrogen oxides from the flue gases of a soda recovery boiler of a pulp mill. In the method, to the flue gases of the soda recovery boiler is at first fed an oxidizing agent, such as chlorine dioxide or ozone, which oxidizes nitrogen oxide to nitrogen dioxide. Subsequently, the flue gases are led into a flue gas scrubber, in which a reagent coming from the circulation of chemicals of the pulp mill is injected into the flue gases, which reagent brought into contact with the nitrogen dioxide reduces the nitrogen dioxide to nitrogen. The flue gas containing nitrogen is led out of the scrubber and the oxidized reagent is led back to the circulation of chemicals of the pulp mill.

Abstract: A method for adjusting the sulphur/sodium ratio in a soda recovery boiler when strong sulphurous odour gases are burned therein. According to the method, sodium is introduced into the soda recovery boiler in an amount proportional to the amount of sulphur either as sodium hydroxide, sodium carbonate compounds or soap, whereby the sodium and sulphur react, forming sodium sulphate, which can be removed from the flue gases together with fly ash.

Abstract: A thickener has a receptacle in which a thickening drum having an axial filtering wall is mounted in a receptacle for rotation about an axis. A liquid-and-solid-materials mass to be thickened is introduced into the one axial end of the thickening drum. Thereby the solid materials contained in the mass to be filtered form a filtering layer on the inner surface of the a filtering wall and liquid filtrate from the mass flows through the filtering layer and wall into the receptacle. At least one barrier plate radially divides the inner space of the thickening drum into axially sequential spaces, the barrier plate being fixed within the thickening drum for rotation therewith. The barrier plate is provided with at least one opening axially therethrough for flow of the mass to be thickened and at least one opening axially therethrough for air flow in the axial direction of the thickening drum. The thickened mass is then discharged from the other axial end of the thickening drum.