Abstract: A fluidized bed boiler plant and a method of preheating combustion gas in a fluidized bed boiler plant. The boiler plant includes a furnace and a combustion gas channel, and a water-steam cycle including an evaporator section, a superheater section including a last superheater and a steam turbine, and a superheating path for conveying steam from the evaporator section via the superheater section to the steam turbine, and a first combustion gas preheater. The fluidized bed boiler plant includes a second combustion gas preheater, a steam extraction line attached in flow connection with the second combustion gas preheater and with the superheating path in a location upstream of the last superheater for conveying steam from the superheating path to the second combustion gas preheater.

Abstract: A fluidized bed boiler plant and a method of preheating combustion gas in a fluidized bed boiler plant. The boiler plant includes a furnace and a combustion gas channel, and a water-steam cycle including an evaporator section, a superheater section including a last superheater and a steam turbine, and a superheating path for conveying steam from the evaporator section via the superheater section to the steam turbine, and a first combustion gas preheater. The fluidized bed boiler plant includes a second combustion gas preheater, a steam extraction line attached in flow connection with the second combustion gas preheater and with the superheating path in a location upstream of the last superheater for conveying steam from the superheating path to the second combustion gas preheater.

Abstract: A method of recovering heat from bottom ash that is discharged from a combustion process in a furnace. Fuel and combustion air are fed into a furnace for combusting the fuel in order to generate heat energy to produce at least one of steam and hot water in a boiler arrangement, in which flue gases and bottom ash are generated. The bottom ash is discharged from the furnace. Heat is recovered from the flue gases. Heat is also recovered to a bottom ash cooling circuit from the bottom ash discharged from the furnace in order to utilize the recovered heat for preheating the combustion air in a heat exchanger. The heat exchanger is arranged in a combustion air heating circuit. Heat is exchanged from the bottom ash cooling circuit to the combustion air heating circuit.

Abstract: A method of recovering heat from bottom ash that is discharged from a combustion process in a furnace. Fuel and combustion air are fed into a furnace for combusting the fuel in order to generate heat energy to produce steam or hot water in a boiler arrangement, in which flue gases and bottom ash are formed. The bottom ash is discharged from the furnace. Heat is recovered from the flue gases, and heat is recovered to a bottom ash cooling water circuit from the bottom ash discharged from the furnace in order to utilize the recovered heat for preheating the combustion air in a heat exchanger.