Steam boilers

Claim 2

A fluidized bed burner steam boiler comprising a fluidized bed of ash and combustible particles, means for fluidizing said particles and causing combustion of said combustible particles, immersed within said bed a number of banks of substantially upright tubes of the type chosen from evaporating tubes and steam heating tubes, an upper and a lower header for each of said banks of tubes, said tubes of each bank extending between said upper and lower headers, said banks being juxtaposed within said bed so that said tubes are substantially evenly distributed over the cross-sectional area of said bed, and an air distribution plate defining the base of said fluidized bed, and in which said lower headers are positioned below said air distribution plate, said upright tubes extending through said distribution plate.

Claim 3

A steam boiler according to claim 1 in which said distribution plate comprises a plate, circular cut-outs in said plate through which said upright tubes extend, annular passages being defined between said tubes and said cut-outs for the passage of fluidizing air to said bed, and annular plates fixed to said tubes and covering said annular passages whereby said fluidizing air passing through said passages is distributed and ash is prevented from falling back into said passages when the supply of fluidizing air is stopped.

Claim 4

A fluidized bed burner steam boiler comprising a cylindrical vessel, a distribution plate extending across said cylindrical vessel and defining with said vessel a region in which ash and combustible particles can be fluidized, means for supplying fluidizing air, said air being arranged to pass upwardly through said distribution plate to fluidize said particles, a number of outlet headers positioned above said bed, said headers when viewed in plan being arranged so as to radiate outwardly from the axis of said cylindrical vessel, a number of inlet headers positioned below said outlet heads and also arranged so that, when viewed in plan, they radiate outwardly from said axis of said cylindrical vessel, banks of substantially upright tubes extends between said inlet and outlet headers, said tubes being of a type chosen from evaporating tubes and steam heating tubes, said banks of tubes being of truncated sector shape, when viewed in plan and being arranged so that said tubes are distributed substantially evenly over the cross-sectional area of said bed, a central upright open-topped tube extending up within said bed centrally of said banks of tubes, said open-topped tube constituting an outlet into which excess particles are arranged to overflow when said bed is fluidized so as to maintain a constant bed height, and means for supplying fluid chosen from steam and water to said tubes for heating.

Claim 5

A fluidized bed burner steam boiler comprising a cylindrical vessel, a distribution plate extending across said cylindrical vessel and defining with said vessel a region in which ash and combustible particles can be fluidized, means for supplying fluidizing air, said air being arranged to pass upwardly through said distribution plate to fluidize said particles, a number of outlet headers positioned above said bed, said headers when viewed in plan being arranged so as to radiate outwardly from the axis of said cylindrical vessel, a number of inlet headers positioned below said outlet heads and also arranged so that, when viewed in plan, they radiate outwardly from said axis of said cylindrical vessel, banks of substantially upright tubes extends between said inlet and outlet headers, said tubes being of a type chosen from evaporating tubes and steam heating tubes, said banks of tubes being of truncated sector shape, when viewed in plan and being arranged so that said tubes are distributed substantially evenly over the cross-sectional area of said bed, a central upright open-topped tube extending up within said bed centrally of said banks of tubes, said open-topped tube constituting an outlet into which excess particles are arranged to overflow when said bed is fluidized so as to maintain a constant bed height, and means for supplying fluid chosen from steam and water to said tubes for heating.

Claim 6

A steam boiler according to claim 3 in which said lower headers are positioned below said distribution plate, said upright tubes extending through said distribution plate.