Fluidised bed burner control

Claim 2

A fluidized bed burner comprising wall means defining a bed region in which combustible articles are arranged to be fluidized and burnt to give ash particles, a porous distributor defining a base for said bed region, means for supplying a fluidizing gas to and through said distributor to fluidize said combustible and ash particles, means for feeding fresh combustible particles to said bed region, and means for continually withdrawing excess particles, said means comprising at least one overflow take-off, vertically adjustable in relation to the height of said bed region, whereby during operation of said burner vertical adjustment of said level of said take-off causes more or less excess particles to overflow from said bed region so varying the height of said bed region.

Claim 3

A burner according to claim 1 in which said wall means define a cross-sectional area which increases with increasing height of said bed region.

Claim 4

A burner according to claim 2 in which said wall means have the shape of an inverted truncated cone.

Claim 5

A fluidized bed burner comprising wall means defining a bed region in which combustable articles are arranged to be fluidized and burnt to give ash particles, a porous distributor defining a base for said bed region, means for supplying a fluidizing gas to and through said distributor to fluidize said combustible and ash particles, means for feeding fresh combustible particles to said bed region, and means for continually withdrawing excess particles, said means comprising at least one overflow take-off, an upright slot in said wall means, a slidable plate covering said slot and being slidable up and down relatively to said slot, and an outlet nozzle through said plate constituting said overflow take-off, whereby as said sliding plate is raised or lowered relatively to said slot, the level of said take-off is correspondingly raised or lowered to cause more or less excess particles to overflow from said bed region so varying the height of said bed region.

Claim 6

A fluidized bed burner comprising wall means defining a bed region in which combustable articles are arranged to be fluidized and burnt to give ash particles, a porous distributor defining a base for said bed region, means for supplying a fluidizing gas to and through said distributor to fluidize said combustible and ash particles, means for feeding fresh combustible particles to said bed region, and means for continually withdrawing excess particles, said means comprising at least one overflow take-off, an upright slot in said wall means, a slidable plate covering said slot and being slidable up and down relatively to said slot, and an outlet nozzle through said plate constituting said overflow take-off, whereby as said sliding plate is raised or lowered relatively to said slot, the level of said take-off is correspondingly raised or lowered to cause more or less excess particles to overflow from said bed region so varying the height of said bed region.

Claim 7

A burner according to claim 4 further comprising a spaced outer wall means surrounding said wall means and defining therewith a passage for the supply of said fluidizing gas to said distributor, whereby the pressure of said gas in said passage is lighter than the pressure within said wall means and said sliding plate and slot are kept substantially ash-free.

Claim 8

In a fluidized bed burner comprising wall means defining a bed region, a porous distributor defining a base for said bed region, and means for supplying fluidizing gas through said distributor to fluidize particles in said bed region, the improvement comprising providing an overflow take-off from said bed region through said wall means, the level of said overflow take-off being adjustable in relation to the height of said bed region, whereby as the level of said take-off is adjusted, more or less particles are arranged to overflow from said bed until the height of said bed adjusts itself to the new level of said overflow take-off.

Claim 9

In a fluidized bed burner comprising wall means defining a bed region, a porous distributor defining a base for said bed region, and means for supplying fluidizing gas through said distributor to fluidize particles in said bed region, the improvement comprising providing an overflow take-off from said bed region through said wall means, the level of said overflow take-off being adjustable in relation to the height of said bed region, whereby as the level of said take-off is adjusted, more or less particles are arranged to overflow from said bed until the height of said bed adjusts itself to the new level of said overflow take-off.

Claim 10

In a burner according to claim 6, the shaping of said wall means so that the cross-sectional area defined by said wall means increases with increasing height.

Claim 11

A steam boiler including a fluidized bed burner comprising wall means defining a bed region in which combustible articles are arranged to be fluidized and burnt to give ash particles, a porous distributor defining a base for said bed region, means for supplying a fluidizing gas to and through said distributor to fluidize said combustible and ash particles, means for feeding fresh combustible particles to said bed region, and means for continually withdrawing excess particles, said means comprising at least one overflow take-off, vertically adjustable in relation to the height of said bed region, whereby during operation of said burner adjustment of said level of said take-off causes more or less excess particles to overflow from said bed region so varying the height of said bed region, and heat exchange means in which water is converted to steam by heat provided by said burner.

Claim 12

A steam boiler including a fluidized bed burner comprising wall means defining a bed region in which combustible articles are arranged to be fluidized and burnt to give ash particles, a porous distributor defining a base for said bed region, means for supplying a fluidizing gas to and through said distributor to fluidize said combustible and ash particles, means for feeding fresh combustible particles to said bed region, and means for continually withdrawing excess particles, said means comprising at least one overflow take-off, vertically adjustable in relation to the height of said bed region, whereby during operation of said burner adjustment of said level of said take-off causes more or less excess particles to overflow from said bed region so varying the height of said bed region, and heat exchange means in which water is converted to steam by heat provided by said burner.

Claim 13

A steam boiler according to claim 8 in which said wall means define a cross-sectional area which increases with increasing height of said bed region.

Claim 14

A steam boiler including a fluidized bed burner comprising wall means defining a bed region in which combustible articles are arranged to be fluidized and burnt to give ash particles, a porous distributor defining a base for said bed region, means for supplying a fluidizing gas to and through said distributor to fluidize said combustible and ash particles, means for feeding fresh combustible particles to said bed region, and means for continually withdrawing excess particles, said means comprising at least one overflow take-off, adjustable in relation to the height of said bed region, whereby during operation of said burner adjustment of said level of said take-off causes more or less excess particles to overflow from said bed region so varying the height of said bed region, and heat exchange tubes which are positioned so as to be a least partially immersed in said bed region, said tubes being either steam raising, superheating or reheating tubes, whereby adjustment of the level of said take-off will, when the boiler is in operation, vary the amount of tube surface within, said bed region.

Claim 15

A steam boiler including a fluidized bed burner comprising wall means defining a bed region in which combustible articles are arranged to be fluidized and burnt to give ash particles, a porous distributor defining a base for said bed region, means for supplying a fluidizing gas to and through said distributor to fluidize said combustible and ash particles, means for feeding fresh combustible particles to said bed region, and means for continually withdrawing excess particles, said means comprising at least one overflow take-off, adjustable in relation to the height of said bed region, whereby during operation of said burner adjustment of said level of said take-off causes more or less excess particles to overflow from said bed region so varying the height of said bed region, and heat exchange tubes which are positioned so as to be a least partially immersed in said bed region, said tubes being either steam raising, superheating or reheating tubes, whereby adjustment of the level of said take-off will, when the boiler is in operation, vary the amount of tube surface within, said bed region.

Claim 16

A steam boiler including a fluidized bed burner comprising wall means defining a bed region in which combustable articles are arranged to be fluidized and burnt to give ash particles, a porous distributor defining a base for said bed region, means for supplying a fluidizing gas to and through said distributor to fluidize said combustible and ash particles, means for feeding fresh combustible particles to said bed region, and means for continually withdrawing excess particles, said means comprising at least one overflow take-off, adjustable in relation to the height of said bed region, whereby during operation of said burner, adjustment of said level of said take-off causes more or less excess particles to overflow from said bed region so varying the height of said bed region, and heat exchange means in which water is converted to steam by heat provided by said burner, said heat exchange means comprising at least one bank of tubes at least partially positioned within said bed region and at least another bank of tubes positioned so as to be heated by convection by the passage of gases from said bed region over it, whereby the adjustment of the level of said take-off will vary the heat pick-up of said heat bank positioned in said bed region relative to that of said tube bank heated by convection.

Claim 17

A steam boiler including a fluidized bed burner comprising wall means defining a bed region in which combustable articles are arranged to be fluidized and burnt to give ash particles, a porous distributor defining a base for said bed region, means for supplying a fluidizing gas to and through said distributor to fluidize said combustible and ash particles, means for feeding fresh combustible particles to said bed region, and means for continually withdrawing excess particles, said means comprising at least one overflow take-off, adjustable in relation to the height of said bed region, whereby during operation of said burner, adjustment of said level of said take-off causes more or less excess particles to overflow from said bed region so varying the height of said bed region, and heat exchange means in which water is converted to steam by heat provided by said burner, said heat exchange means comprising at least one bank of tubes at least partially positioned within said bed region and at least another bank of tubes positioned so as to be heated by convection by the passage of gases from said bed region over it, whereby the adjustment of the level of said take-off will vary the heat pick-up of said heat bank positioned in said bed region relative to that of said tube bank heated by convection.