Abstract: A circulating fluidized bed boiler includes a furnace for combusting solid carbonaceous fuel in a fast fluidized bed. A solids separator is adjacent to a sidewall of the furnace and separates solids entrained with exhaust gas discharged via an outlet channel. A gas seal conveys at least a portion of the separated solids to a first fluidized bed heat exchange chamber that is arranged downstream of the gas seal and has internal heat exchange surfaces. A first lift channel has a lower end connected to a bottom portion of the first fluidized bed heat exchange chamber and an upper end connected to an upper end of a first return channel for discharging solids from the first fluidized bed heat exchange chamber and taking the cooled solids to a lower portion of the furnace. A second fluidized bed heat exchange chamber is arranged adjacent to a lower sidewall of the furnace.

Abstract: A circulating fluidized bed boiler includes a rectangular furnace having multiple particle separators connected to an upper portion of each of a front wall and a back wall of the furnace. Each particle separator includes a gas outlet, and a flue gas duct system connected to the gas outlets for conducting cleaned flue gas to a back pass. The particle separators are arranged in pairs. Each pair includes a front separator arranged adjacent to the front wall and a back separator arranged adjacent to the back wall. The flue gas duct system includes cross over ducts, each duct connecting the gas outlet of a front separator of a pair of particle separators, across and over the furnace, to the gas outlet of the back separator of the same pair of particle separators, and to the back pass, which back pass is arranged on the back wall side of the furnace.

Abstract: A fluidized bed reactor includes a bottom portion, a roof portion, and side walls vertically extending between the bottom portion and the roof portion, forming a reaction chamber of the reactor. At least one side wall of the reaction chamber forms at least one vertical indentation in the reaction chamber, which indentation extends from the plane of the at least one side wall towards the reaction chamber. The indentation extending from the plane of the at least one side wall towards the reaction chamber is formed of a portion of the at least one side wall, protruding from the plane of the at least one side wall towards the reaction chamber, and the portion of the at least one side wall includes at least two substantially vertical indenting wall portions deviating from the plane of the at least one side wall at vertical lines within a distance from each other.

Abstract: A boiler system includes an arrangement for drying fuel material to be combusted in the boiler system. A combustion chamber combusts fuel material, and generates ash and flue gases. An ash removal conduit connected to the combustion chamber leads ash out of the combustion chamber. A flue gas conduit connected to the combustion chamber leads Hue gases out of the combustion chamber. A flue gas heat recovery system, arranged to the flue gas conduit, recovers heat from the flue gases. A fuel dryer, provided with a first heat transfer device, transfers heat into the fuel to be dried. A second heat transfer device is arranged in connection with the flue gas conduit downstream of the flue gas heat recovery system. A third heat transfer device is arranged in connection with the ash removal conduit and a fourth heat transfer device is arranged in heat transfer connection with the fuel dryer.

Abstract: A circulating fluidized bed boiler including a furnace for combusting solid carbonaceous fuel in a fast fluidized bed, the furnace having walls made of water/steam tube panels and used for evaporating water fed therein. A solids separator arranged adjacent to a sidewall of the furnace separates solids entrained with exhaust gas discharged via an outlet channel from an upper portion of the furnace. A gas seal conveys at least a portion of the separated solids to a first fluidized bed heat exchange changer arranged downstream of the gas seal and has internal heat exchange surfaces. A first lift channel has a lower end connected to a bottom portion of the first fluidized bed heat exchanger chamber and an upper end connected to an upper end of a first return channel for discharging solids from the first fluidized bed heat exchange chamber and for taking the cooled solids to a lower portion of the furnace.

Abstract: A fluidized bed boiler plant and a method of combusting sulfurous fuel in the fluidized bed boiler plant, a furnace of which plant is provided with a fluidized bed of particles. Sulfurous fuel, CaCO3-containing sulphur-binding agent and combusting air are introduced to the bed of particles, whereby fuel burns and generates flue gases and the sulphur-binding agent calcinates to CaO and binds SO2 generated in the combustion. Energy is recovered to a heat exchange medium circulating in heat exchange tubes of a condensing heat exchanger arranged in a flue gas channel, and a water solution of acid condensing on outer surfaces is neutralized by mixing it in a mixing vessel to a CaO-containing ash from a plant, preferably, fly ash collected by a dust separator.

Abstract: A method of feeding at least one of light, fine and moist fuel into a furnace of a circulating fluidized bed boiler. Fuel is fed into the furnace through a fuel feed and the fuel is combusted in a turbulent, circulating fluidized bed. A fuel feed area is isolated from the turbulent circulating bed by arranging the fuel feed along at least one channel arranged in a wall of the furnace. Solids of the circulating bed material are introduced onto a first grid section at the bottom of the fuel feed area. The fuel and the solids are mixed and fluidized above the grid section to form a fuel-solids mixture that flows laterally onto a second grid section and a third grid section where the mixture is fluidized. The fluidized bed material is circulated both inside and outside of the furnace. The bed material is separated from the flue gases and returned to the furnace.

Abstract: A method of feeding at least one of light, fine, volatile and moist fuel into a furnace of a circulating fluidized bed boiler. Fuel is introduced into the furnace and is combusted in the presence of a fluidized bed material to form flue gases. The fluidized bed material is circulated both inside the furnace in an internal circulation in which bed material returns along walls of the furnace down to the bottom of the furnace, and outside the furnace in an external circulation that includes at least a solids separator arranged in flow communication with the furnace. Bed material is separated from the flue gases in the separator. The flue gases are removed from the separator for further treatment. The separated bed material is returned to the furnace.

Abstract: A fluidized bed reactor includes a bottom portion, a roof portion and side walls vertically extending between the bottom portion and the roof portion, forming a reaction chamber of the fluidized bed reactor. A solids separator is in connection with the reaction chamber. At least one side wall of the reaction chamber forms at least one indentation in the reaction chamber, which indentation is substantially vertical and extends from the plane of the side wall towards the reaction chamber.

Abstract: A circulating fluidized bed boiler includes a rectangular furnace which is horizontally enclosed by a front wall, a back wall and two sidewalls, and multiple particle separators connected to the upper portion of each of the front wall and the back wall. Each particle separator includes a gas outlet, and flue gas duct system connected to the gas outlets for conducting cleaned flue gas to a back pass. The particle separators are arranged in pairs of particle separators. Each pair of particle separators includes a front separator arranged adjacent to the front wall and a back separator arranged adjacent to the back wall. The flue gas duct system includes cross over ducts, each cross over duct connecting the gas outlet of a front separator of a pair of particle separators, across and over the furnace, to the gas outlet of the back separator of the same pair of particle separators, and to the back pass, which back pass is arranged on the back wall side of the furnace.

Abstract: A circulating fluidized bed boiler includes a furnace for combusting carbonaceous fuel, at least one outlet channel connected to the upper portion of the furnace for removing flue gas and solid particles generated in the combustion of the fuel, each outlet channel provided with a particle separator attached with a flue gas channel for transferring cleaned flue gas and a return duct for transferring separated solid particles to the lower portion of the furnace. The return duct is provided with a gas seal, a heat exchange chamber, a lift channel and an overflow conduit, in which solid particles exiting the gas seal are guided to the upper portion of the heat exchange chamber and from the lower portion of the heat exchange chamber through the lift channel to the furnace, or directly from the upper portion of the heat exchange chamber through the overflow conduit to the furnace.

Abstract: A method of combusting oil shale in a circulating fluidized bed boiler. Fuel, including oil shale, is introduced into a furnace of the circulating fluidized bed boiler, primary oxygenous gas is introduced through a bottom grid of the furnace, and secondary oxygenous gas is introduced to the furnace at a first level above the level of the bottom grid. The primary oxygenous gas is introduced to the furnace at a rate providing below the first level a fluidizing velocity of less than 2.5 m/s, and the primary and secondary oxygenous gases are introduced to the furnace in such a way that a circulating fluidized bed is formed, and the fluidizing velocity at the first level is less than 70% of the fluidizing velocity in the upper portion of the furnace.

Abstract: A fluidized bed boiler plant and a method of combusting sulfurous fuel in the fluidized bed boiler plant, a furnace of which plant is provided with a fluidized bed of particles. Sulfurous fuel, CaCO3-containing sulphur-binding agent and combusting air are introduced to the bed of particles, whereby fuel burns and generates flue gases and the sulphur-binding agent calcinates to CaO and binds SO2 generated in the combustion. Energy is recovered to a heat exchange medium circulating in heat exchange tubes of a condensing heat exchanger arranged in a flue gas channel, and a water solution of acid condensing on outer surfaces is neutralized by mixing it in a mixing vessel to a CaO-containing ash from a plant, preferably, fly ash collected by a dust separator.

Abstract: A method of reducing sulfur dioxide emissions of a circulating fluidized bed boiler. Sulfur-containing carbonaceous fuel is fed to a furnace of the boiler, and calcium carbonate is fed to the furnace at a rate relative to the first stream such that the molar ratio of calcium in the second stream to sulfur in the first stream is at most about 1.0. The fuel is combined so that the sulfur is oxidized to form sulfur dioxide. The calcium carbonate is calcined to form calcium oxide and the calcium oxide is used to sulfate the sulfur dioxide to form calcium sulfate. Flue gas particles are separated using a hot loop separator, and the separated particles are returned to the furnace. A sulfur-reduction stage downstream of the furnace further reduces the sulfur content of the flue gases.

Abstract: A method of combusting oil shale or fuel having similar properties as oil shale in a circulating fluidized bed boiler. The method includes the steps of (a) introducing fuel into a furnace of the circulating fluidized bed boiler, (b) introducing primary oxygenous gas through a bottom grid of the furance, and (c) introducing secondary oxygenous gas to the furnace at a first level above the level of the bottom grid. The primary oxygenous gas is introduced to the furnace at a rate providing below the first level a fluidizing velocity of less than 2.5 m/s, and the primary and secondary oxygenous gases are introduced to the furnace in such a way that the fluidizing velocity below the first level is less than 70% of the fluidizing velocity in the upper portion of the furnace.

Abstract: A boiler plant, including a combustion section, a heat exchange section including heat exchange surfaces, arranged above the combustion section and having a flow direction from the bottom upwards, and a stationary supporting structure. The combustion section and the heat exchange section are separate chambers, flexibly joined with each other, and the chambers are each separately hung from their upper part to the stationary supporting structure.

Abstract: A boiler plant, for example, a pulverized coal fired plant or a circulating fluidized bed boiler plant, comprising a combustion section, a heat exchange section arranged above the combustion section and containing heat exchange surfaces, in which heat exchange section the flow direction of the flue gas is from the bottom upwards, and a stationary supporting construction. In the boiler plant, the combustion section and the heat exchange section are separate chambers, flexibly joined with each other, and each chamber separately hung from the top part to a stationary supporting structure, preferably to its horizontal supporting planes.

Abstract: A method of reducing sulfur dioxide emissions of a circulating fluidized bed boiler includes the steps of (a) feeding a first stream comprising a sulfur-containing carbonaceous fuel to a furnace of the boiler; (b) feeding a second stream comprising calcium carbonate to the furnace at a rate relative to the first stream such that the molar ratio of calcium in the second stream to sulfur in the first stream (the Ca/S molar ratio) is between about 1.2 and about 0.