Air nozzle arrangement in a fluidized bed boiler, grate for a fluidized bed boiler, and a fluidized bed boiler

Patent metadata

Field	Value
Publication number	US-9976739-B2
Application number	US-201314442378-A
Country	US
Kind code	B2
Filing date	Nov 7, 2013
Priority date	Nov 13, 2012
Publication date	May 22, 2018
Grant date	May 22, 2018

Abstract

An air nozzle arrangement for a fluidized bed boiler, comprising an air feed pipe and an air nozzle which limit an air feed duct configured to supply air to the furnace of the fluidized bed boiler. The air nozzle arrangement comprises a surface configured to guide coarse material along said surface. At least part of said surface is thermally insulated from the air nozzle and/or the air feed pipe. Furthermore, at least part of said surface is configured to protect at least part of said air nozzle and/or air feed pipe. Thus, the temperature of said surface is configured to be high when the fluidized bed boiler is in operation, whereby the solidification of molten material of the fluidized bed in the air nozzle arrangement is reduced.

First claim

The invention claimed is:

1. A fluidized bed boiler comprising:
a furnace and an air nozzle arrangement, the air nozzle arrangement comprising:
several air nozzles spaced from each other in a longitudinal direction of the air nozzle arrangement;
an air feed pipe that is connected to one of the air nozzles and that, with the air nozzle, limits an air feed duct;
the air feed duct being configured to supply air to a furnace of the fluidized bed boiler; and
a surface, wherein at least part of said surface is configured to protect at least part of at least one of, the air nozzle, and the air feed pipe,
and
wherein at least part of said surface is thermally insulated from at least one of , the air nozzle, and the air feed pipe;
wherein at least one air nozzle is configured to supply air to a furnace of the fluidized bed boiler in a direction which forms an angle not larger than 80 degrees to a horizontal plane and forms an angle of at least 10 degrees to the longitudinal direction;
wherein at least 50% of the surface is arranged at an angle of at least 10 degrees to the horizontal plane, whereby
the surface is configured to guide coarse material along said surface in such a way that liquid metal carried along with solids of the furnace does not solidify when it hits the surface, and the solids are guided along the surface downwards and to one side according to the shape of the surface, wherein the temperature of said surface is configured to be high when the fluidized bed boiler is in operation, whereby the solidification of molten material of the fluidized bed at the air nozzle arrangement is reduced, and
the air flow produced by the air nozzle is configured to guide coarse material towards an ash removal zone of a grate or a coarse material outlet of the fluidized bed boiler; wherein the air nozzle arrangement is configured to supply combustion air to the furnace of the fluidized bed boiler.

2. The fluidized bed boiler of claim 1 wherein the temperature of said surface is configured to be higher than the temperature of one of the air nozzles when the fluidized bed boiler is in operation.

3. The fluidized bed boiler according to claim 1 comprising a plate comprising said surface, wherein said plate is replaceable, alone or together with other parts.

4. The fluidized bed boiler of claim 1 wherein said surface is configured to protect at least two air nozzles.

5. The fluidized bed boiler of claim 1 wherein at least part of the surface is arranged at least partly above said air nozzle.

6. The fluidized bed boiler according to claim 1 comprising a grate beam, the grate beam comprising:
the air nozzle arrangement;
an air beam, the air beam being configured to supply air to at least said air feed duct;
the air beam comprising walls and at least one heat exchanger pipe;
the heat exchanger pipe being provided in or on one of said walls; and
wherein the one of said walls being arranged in contact with coarse material when the fluidized bed boiler is in operation, wherein the heat exchanger pipe is configured to cool the air beam and to recover heat from coarse material.

7. The fluidized bed boiler according to claim 6 , wherein the grate beam has a profile form extending in the longitudinal direction,
said air nozzles are arranged on a first upper side of said grate beam, the first upper side defining a height direction of the grate beam, the height direction extending from a second lower side of the grate beam, opposite to the first upper side, to the first upper side of the grate beam,
the grate beam having a height in said height direction, and
the grate beam having a width in a direction perpendicular to said height direction and perpendicular to said longitudinal direction,
the height being greater than the width.

8. The fluidized bed boiler according to claim 6 , comprising:
a grate;
a first air nozzle arrangement with several air nozzles spaced from each other in the longitudinal direction; and
a second air nozzle arrangement with several air nozzles spaced from each other in the longitudinal direction of the second air nozzle arrangement, in which grate the second air nozzle arrangement is spaced from the first air nozzle arrangement in a cross direction transverse to the longitudinal direction, wherein at least one of an ash removal zone and a coarse material outlet is left between the first and second air nozzle arrangements, for removing coarse material from the fluidized bed boiler.

9. The fluidized bed boiler according to claim 8 , wherein
said at least one of an ash removal zone and a coarse material outlet, is limited by a wall, one direction of the wall forming an angle not larger than 5 degrees to a vertical direction, or
at least 5 degrees to the horizontal direction.

10. A fluidized bed boiler according to claim 1 , comprising
a grate comprising several grate beams, the grate beams comprising air beams,
said air beams having a profile form extending in the longitudinal direction,
said air nozzles being arranged on a first upper side forming at least a part of the profile the first upper side of said air beam defining a height direction of the air beam, the height direction extending from a second lower side of the air beam, opposite to the first upper side, to the first upper side of the air beam,

a width direction is defined perpendicular to said height direction and perpendicular to said longitudinal direction of the air beam, in which grate the grate beams are spaced from each other in said width direction, wherein an ash removal zone is left between at least two of the several grate beams;
wherein the fluidized bed boiler further comprising:
a duct or a funnel for collecting coarse material; in which fluidized bed boiler at least part of the coarse material in the fluidized bed is configured to flow along said surface of the air nozzle arrangement of the fluidized bed boiler, via said ash removal zone to said duct or funnel for collecting ash;
wherein at least part of said air nozzle or said air feed pipe is protected with said surface, at least part of said surface is thermally insulated from at least one of said air nozzle and said air feed pipe, wherein the solidification of molten solids on said surface is reduced, and a heat exchanger pipe of said grate beam is configured to cool the grate beam and to recover heat from the coarse material passing through said ash removal zone.

11. A method for removing coarse material from a fluidized bed boiler, the fluidized bed boiler comprising:
a furnace,
several air nozzles spaced from each other in a longitudinal direction,
an air feed pipe,
a grate, and
an ash removal zone or a coarse material outlet;
the method comprising:
supplying combustion air by an air nozzle to the furnace of the fluidized bed boiler;
removing coarse material from the fluidized bed boiler via the ash removal zone or the coarse material outlet;

protecting at least part of at least one of the air nozzle and the air feed pipe by a surface, of which at least part is thermally insulated from at least one of the air nozzle and the air feed pipe,
guiding the coarse material along the surface of which at least 50% is arranged at an angle of at least 10 degrees to a horizontal plane, toward said ash removal zone or coarse material outlet in such a way that liquid metal carried along with the solids of the furnace does not solidify when it hits the surface, and the solids are guided along the surface downwards and to one side according to the shape of the surface and supplying air by the air nozzle to the furnace of the fluidized bed boiler in a direction towards said ash removal zone or coarse material outlet.

Assignees

• Valmet Technologies Oy

Inventors

• Kainu Vesa
• Leppälä Jukka-Pekka

Classifications

• F23H3/02

  internally cooled · CPC title

• F23C10/24

  Devices for removal of material from the bed (devices for controlling the level of the bed or the amount of material in the bed F23C10/30) · CPC title

• F23C2900/10007

  Spouted fluidized bed combustors · CPC title

• F23C10/20 Primary

  Inlets for fluidisation air, e.g. grids; Bottoms · CPC title

• F23L1/02

  by discharging the air below the fire · CPC title