Abstract: A grate assembly for a fluidized bed boiler comprises a number of parallel sparge pipes or the like extending side-by-side in a substantially horizontal plane and provided with elements for supplying fluidizing air from within the sparge pipes or the like into a combustion chamber located above the grate assembly. The discharge of some of the fluidized bed materials is effected through an aperture system formed between the adjacent sparge pipes into a receiver unit fitted below the grate assembly. The sparge pipes are provided with a cooling medium circulation by means of a duct assembly.

Abstract: A single-drum recovery boiler comprising a superheater (2), boiler bank elements (3a) forming a boiler bank, and elements (3b) forming an economizer. In the recovery boiler, a plurality of boiler bank elements (3a) and economizer elements (3b) are disposed alternately so that a boiler bank--economizer unit (3) is achieved where the ratio between the boiler bank elements and the economizer elements is optimized in relation to the operating conditions of the boiler.

Abstract: A process for desulfurization of fuel combustion gases and a new reactor wherein the primary flue gas stream containing sulfur oxides and alkaline oxide solids flows into the reactor vessel. A plurality of baffle columns is positioned at the top of the reactor vessel which serve to separate the primary stream into a plurality of first streams containing substantially all of the alkaline oxide solids and a plurality of second streams comprising substantially solids-free gas. The first streams are wetted after which they recombine with the second streams to produce reaction product sulfates and sulfites. The reaction product is substantially dry because the hot second streams cause evaporation of substantially all of the moisture from the wetted first streams.

Abstract: In a method of wetting particles contained in a gas stream including particles and gas, a primary gas stream containing the particles is separated into first and second gas streams such that the first gas stream includes substantially all the particles of the primary gas stream. The particles are wetted in the first gas stream with water in a wetting stage. The amount of water which is introduced into the wetting stage exceeds that amount of water which is capable of reducing the temperature of the first gas stream below its dew point. The resulting first and second gas streams are then combined into an aggregate gas stream downstream of the wetting stage to produce an aggregated gas stream having a temperature greater than the dew point of the aggregated gas.

Abstract: A combustion unit for a circulation process comprises a reactor chamber and at least one particle separator placed inside the reactor chamber in the upper part thereof. At least the first outer casing of the particle separator is arranged to form a heat transfer surface. A flue gas inlet into the first outer casing is arranged to extend for the entire circumference of the casing.

Abstract: The invention relates to a method for decreasing emissions of nitrogen oxides and sulfur oxides when burning fuel which contains nitrogen and sulfur. According to the invention this is carried out by feeding fuel (4) and oxygen-containing gas (5) into a combustion reactor (1) the temperature of which is preferably 900.degree.-1500.degree. C., and that the combustion gases formed are directed into a suspension reactor (2) the temperature of which is preferably 750-1050.degree. C. and into which a pulverous material which binds sulfur oxides is fed so that the suspension density is 1-200 kg/m.sup.3, the oxygen concentration in the combustion reactor (1) and the suspension reactor (2) being controlled so that their total air coefficient is about 0.

Abstract: The invention relates to a process and apparatus for causing the sulfur dioxide of flue gases to react to form solid sulfates and sulfites which can be separated from the flue gases. Sulfur dioxide containing flue gases (16) are directed according to the invention into one end of an oblong reaction zone (4), in addition to which pulverous calcium compounds and water are directed separately into the reaction zone at several points, and finally from the opposite end a flue gas suspension is withdrawn and directed to dust separation (5). By feeding the pulverous reagent and the water separately into the reactor 4, the problems involved in the preparing, handling and spraying of an aqueous slurry are avoided, in addition to which the retention time and the reaction conditions can be regulated easily in the oblong reactor 4.