Circulating fluidized bed boiler

A boiler comprising:

• a combustion chamber having an exterior surface, means for circulating water about the exterior surface of said combustion chamber, tubes located within said means for circulating water, means for feeding combustion gases from said combustion chamber through said tubes located within said means for circulating water, a bed for receiving particulate material, said bed being enclosed within said combustion chamber and having first and second opposite ends, said bed also having a base which is inclined upwardly from said first end thereof to said second end thereof, means for feeding air to said bed to effect fluidisation of said material and circulation of said material by movement thereof from said first end to said second end in an upper region of the bed and from said second end to said first end in a lower region of the bed, and deflection means located over the bed material adjacent said first end to limit expansion of the bed adjacent said first end.