Abstract: A method of preventing blockage of circulating bed material in a circulating fluidized bed reactor includes collecting a continuously flowing bed of solid particles in a gas lock in a return leg of a reactor, measuring gas lock bed pressure values within the bed of the particles, generating a gas lock bed height indication signal on the basis of measured gas lock bed pressure values. A definition stage includes defining and storing to a control system a range of normal gas lock bed height indication signals, formed in normal circulation flow conditions, as a function of the reactor load, and defining and storing to the digital control system a reactor load dependent alarm criterion. The method includes comparing a current gas lock bed height indication signal with the reactor load dependent alarm criterion, and decreasing the reactor load if the current indication signal fulfils the reactor load dependent alarm criterion.

Abstract: An arrangement for controlling a flow of solid particles includes a vertical inlet pipe for directing solid particles downwards and having a bottom at a level L0, a first outlet chute and a second outlet chute in particle flow connection with the vertical inlet pipe and a fluidizing device for directing controlled first and second sub flows to the first and second outlet chutes. The arrangement includes a branch in particle flow connection with an opening on a side wall of the vertical inlet pipe for directing the first sub flow of solid particles to the first outlet chute and a horizontally extending intermediate pipe for directing the second sub flow of solid particles to the second outlet chute. The intermediate pipe includes at least one nozzle feeding fluidizing gas to the intermediate pipe and has a first end in particle flow connection with the bottom of the inlet pipe.

Abstract: An arrangement for controlling a flow of solid particles includes a vertical inlet pipe for directing solid particles downwards and having a bottom at a level L0, a first outlet chute and a second outlet chute in particle flow connection with the vertical inlet pipe and a fluidizing device for directing controlled first and second sub flows to the first and second outlet chutes. The arrangement includes a branch in particle flow connection with an opening on a side wall of the vertical inlet pipe for directing the first sub flow of solid particles to the first outlet chute and a horizontally extending intermediate pipe for directing the second sub flow of solid particles to the second outlet chute. The intermediate pipe includes at least one nozzle feeding fluidizing gas to the intermediate pipe and has a first end in particle flow connection with the bottom of the inlet pipe.

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.