Method for heating a heat exchange medium in a fluidized bed boiler, a fluidized bed boiler, and a loopseal heat exchanger

Abstract

A method for heating a heat exchange medium in a fluidized bed boiler (), the method comprising burning first fuel () in a first furnace () of the fluidized bed boiler () to produce first flue gas (); recovering heat from the first flue gas () to a heat exchange medium using a first heat exchanger (); conveying the heat exchange medium from the first heat exchanger () to a second heat exchanger (), of which at least a part is arranged in contact with a fluidized bed of the fluidized bed boiler (); burning second fuel () in a second furnace () of the fluidized bed boiler () to produce second flue gas (); conveying the heat exchange medium from the second heat exchanger () to a third heat exchanger (); and recovering heat from the second flue gas () to the heat exchange medium using the third heat exchanger (). A fluidized bed boiler () for performing the method. A loopseal heat exchanger () that is, when installed in a loopseal of a circulating fluidized bed boiler, configured to burn second fuel () in a second furnace () of the loopseal heat exchanger () to produce second flue gas (); convey the heat exchange medium from the second heat exchanger () to a third heat exchanger (); and recover heat from the second flue gas () to the heat exchange medium using the third heat exchanger ().