COMBUSTOR AIR BAG GRID FOR USE WITHIN A FLUIDIZED BED REACTOR, AND A FLUIDIZED BED REACTOR

Abstract

A combustor air bar grid for use within a fluidized bed reactor includes at least two main air collector bars in fluid communication with a source of fluidizing gas, a plurality of primary air bars that are transversal to the main air collector bars and arranged on the at least two main air collector bars such that the main air collector bars support them, and in fluid communication to at least two of the main air collector bars. The main air collector bars and the primary air bars define ash removal openings in the air bar grid and a plurality of fluidized nozzles are arranged to each of the primary air bars for fluidizing the bed reactor. A fluidized bed reactor includes such a combustor air bar grid.

Claims

1.-12. (canceled)

13. A combustor air bar grid for use within a fluidized bed reactor, the combustor air bar grid comprising: at least two main air collector bars in fluid communication with a source of fluidizing gas; a plurality of primary air bars that are transverse to the main air collector bars and arranged on the at least two main air collector bars such that the main air collector bars support the plurality of primary air bars, the plurality of primary air bars being in fluid communication with at least two of the main air collector bars, and the main air collector bars and the primary air bars defining ash removal openings in the air bar grid; a plurality of fluidizing nozzles arranged to each of the primary air bars for fluidizing the bed reactor; and a number of ash hoppers arranged beneath the ash removal openings, wherein the main air collector bars are configured to form external air-cooled walls for the ash hoppers that are cooled with the pressurized fluidizing gas.

14. The combustor air bar grid according to claim 13, wherein the main air collector bars are in fluid communication with the primary air bars via fluidizing gas transmitting openings formed in the upper side of each collector bar and in the bottom side of each primary air bar that overlap with each other.

15. The combustor air bar grid according to claim 13, further comprising a number of support beams or support bars arranged to support the main air collector bars, of which vertical support beams or bars are arranged directly below the main air collector bars.

16. The combustor air bar grid according to claim 15, further comprising an essentially horizontal frame structure.

17. The combustor air bar grid according to claim 13, wherein the upper parts of the ash hoppers are laterally aligned with and in mechanical contact with the main air collector bars.

18. The combustor air bar grid according to claim 13, wherein the main air collector bars are connected to boiler pressure parts by using at least one expansion joint.

19. The combustor air bar grid according to claim 13, wherein the at least two main air collector bars and the plurality of the primary air bars are hollow beams of metal, forming conduits for the fluidizing gas.

20. The combustor air bar grid according to claim 13, wherein the main air collector bars and the primary air bars comprise a hollow passageway for the pressurized fluidizing gas.

21. The combustor air bar grid according to claim 13, wherein the combustor air bar grid is constructed as a modular combustor air bar grid comprising a number of modules, such that, in the modules, the main air collector bars have a length allowed for normal rail or road transport, or for an abnormal or an oversize load, between 2.5 and 4 meters.

22. The combustor air bar grid according to claim 21, wherein the main air collector bars comprise segments composed of modules joined together by welding.

23. The combustor air bar grid according to claim 22, wherein each of the modules has a length allowed for normal road transport, or for an abnormal or an oversize load, between 2.50 and 3.50 meters.

24. The combustor air bar grid according to claim 23, wherein the combustor air bar grid comprises openings at the main air collector bars and the primary air bars for joining the hollow passageway in the main air collector bars and the primary air bars.

25. The combustor air bar grid according to claim 24, wherein the openings are arranged at overlapping locations at the primary air bars and the main air collector bars.

26. A fluidized bed reactor comprising a furnace having a combustor air bar grid, the combustor air bar grid comprising: at least two main air collector bars in fluid communication with a source of fluidizing gas; a plurality of primary air bars that are transverse to the main air collector bars and arranged on the at least two main air collector bars such that the main air collector bars support the plurality of primary air bars, the plurality of primary air bars being in fluid communication with at least two of the main air collector bars, and the main air collector bars and the primary air bars defining ash removal openings in the air bar grid; a plurality of fluidizing nozzles arranged to each of the primary air bars for fluidizing the bed reactor; and a number of ash hoppers arranged beneath the ash removal openings, wherein the main air collector bars are configured to form external air-cooled walls for the ash hoppers that are cooled with the pressurized fluidizing gas.

27. The fluidized bed reactor according to claim 26, wherein the main air collector bars are in fluid communication with the primary air bars via fluidizing gas transmitting openings formed in the upper side of each collector bar and in the bottom side of each primary air bar that overlap with each other.

28. The fluidized bed reactor according to claim 26, further comprising a number of support beams or support bars arranged to support the main air collector bars, of which vertical support beams or bars are arranged directly below the main air collector bars.

29. The fluidized bed reactor according to claim 28, further comprising an essentially horizontal frame structure.

30. The fluidized bed reactor according to claim 26, wherein the upper parts of the ash hoppers are laterally aligned with and in mechanical contact with the main air collector bars.

31. The fluidized bed reactor according to claim 26, wherein the main air collector bars are connected to boiler pressure parts by using at least one expansion joint.

32. The fluidized bed reactor according to claim 26, wherein the at least two main air collector bars and the plurality of the primary air bars are hollow beams of metal, forming conduits for the fluidizing gas.

33. The fluidized bed reactor according to claim 26, wherein the main air collector bars and the primary air bars comprise a hollow passageway for the pressurized fluidizing gas.

34. The fluidized bed reactor according to claim 26, wherein the combustor air bar grid is constructed as a modular combustor air bar grid comprising a number of modules, such that, in the modules, the main air collector bars have a length allowed for normal rail or road transport, or for an abnormal or an oversize load, between 2.5 and 4 meters.

35. The fluidized bed reactor according to claim 34, wherein the main air collector bars comprise segments composed of modules joined together by welding.

36. The fluidized bed reactor according to claim 35, wherein each of the modules has a length allowed for normal road transport, or for an abnormal or an oversize load, between 2.50 and 3.50 meters.

37. The fluidized bed reactor according to claim 36, wherein the combustor air bar grid comprises openings at the main air collector bars and the primary air bars for joining the hollow passageway in the main air collector bars and the primary air bars.

38. The fluidized bed reactor according to claim 37, wherein the openings are arranged at overlapping locations at the primary air bars and the main air collector bars.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In the following, the combustor air bar grid and the fluidized bed reactor are explained in more detail with reference to the exemplary embodiments shown in FIGS. 1 to 4, of which:

[0029] FIG. 1 shows a steam generator system comprising a circulating fluidized bed reactor;

[0030] FIG. 2 is a lateral view of a combustor air bar grid;

[0031] FIG. 3 is an end view of the combustor air bar grid of FIG. 2; and

[0032] FIG. 4 is a bubbling fluidized bed reactor boiler with the combustor air grid according to the invention.

[0033] The same reference numerals refer to the same technical features in all figures.

DETAILED DESCRIPTION

[0034] FIG. 1 shows a steam generating system 10. The structure and operation of the steam generating system 10 may be, up to the combustor air grid 1, the ash hoppers 6 and the support structures, identical to the steam generating system 10 disclosed in U.S. Pat. No. 5,425,331, which is hereby incorporated by reference.

[0035] The steam generating system 10 includes a fluidized bed reactor 12 (which in FIG. 1 is illustrated as a circulating fluidized bed reactor and in FIG. 4 as a bubbling fluidized bed reactor), a cyclone separator 14, and a heat recovery area 16.

[0036] An air bar grid 1 is provided in the lower portion of the fluidized bed reactor 12 and will be described in detail below with reference to the embodiments shown in FIGS. 2 and 3.

[0037] The cyclone separator 14 receives a mixture of air and the gaseous products of combustion from the fluidized bed reactor 12 along with solid particles entrained thereby. The separator 14 operates to separate the solids from the gases, and the latter are passed to the heat recovery area 16. The solids from the separator 14 fall down into a tapering section 14a of the separator where they are reinjected, via a return leg 22, to the lower portion of the reactor section 12. The gases, after passing through the heat recovery area 16, exit via an outlet conduit 16a.

[0038] The fluidized bed reactor 12 includes a front wall 24a, a spaced, parallel rear wall 24b, and two spaced, parallel side walls (not shown in FIG. 1), which extend perpendicular to the front and rear walls to form an enclosure.

[0039] At least one distributor 27 extending through the front wall 24a, back wall 24b, or side walls, for introducing fuel into the fluidized bed can be used to feed fuel into the fluidized bed reactor 12, as shown in FIG. 1. Alternatively, or in addition, feeding of the fuel can be carried out with a silo-hopper and a screw-feeder that are disposed above the fluidized bed reactor 12 and register with an opening formed in its roof for introducing biomass or waste fuels, such as municipal refuse, onto the upper surface of a fluidized bed disposed above the combustor air bar grid 1. The waste fuel may contain non-combustible material, such as bottles and cans.

[0040] A distributor 28 extends through the front wall 24a for introducing bed make-up material onto the upper surface of the fluidized bed. This make-up material consists, in general, of sand and/or limestone, or dolomite, for adsorbing the sulphur oxides released during the combustion of the waste fuel. It is understood that other distributors can be associated with the walls 24a, 24b and any or both of the side walls, for distributing bed make-up material onto the bed, as needed.

[0041] In the operation of the steam generator 10, a quantity of biomass or waste fuel and bed make-up material are introduced through the screw feeder 27 and the distributor 28, respectively, and build up on the upper surface of the air grid 1. Fluidizing gas preferably, air from an external source is supplied to the plenum chamber 49 at a sufficient volume by a fluidizing gas source 9. Preferably, combustion fluidized air is used as the fluidizing gas. The pressurized fluidizing gas causes the bed make-up material above the combustor air bar grid 1 to become fluidized in the furnace 26. Burners (not shown) are disposed in the plenum chamber 49 to raise the temperature of the fluidizing gas to a temperature sufficient to commence the burning of the biomass or waste fuel material disposed above the combustor air bar grid 1. Auxiliary fuel, such as coal, may be provided by the distributor 28 in the event that the biomass or waste fuel has a low calorie content. Once the biomass or waste fuel inside the reactor 12 starts burning with the fluidizing gas, ignition by the burners and/or the auxiliary fuel is reduced or ceased as needed.

[0042] As the combustion progresses, additional waste fuel and bed make-up material are introduced through the screw feeder 27 and the distributor 28, respectively, to the fluidized bed reactor 12. The non-combustible material, ash and spent bed make-up material, are gravitationally and pneumatically transported downwardly as the fluidizing gas and the products of combustion move upwardly within the fluidized bed reactor 12. The incombustible solids move downwardly through the fluidized bed reactor 12 to the upper surface of the combustor air bar grid 1, pass downwardly through the combustor air bar grid 1 through the openings in the air bar grid 1, and continue to descend within the ash hoppers 6 as heat is transferred by convection from the bed material by fluidizing gas streaming from air nozzles or pipes with air from the primary air bars, thus, air cooling the external walls of the ash hoppers 6. The incombustible solids exit the hoppers 6 though an opening in the base of the hopper and are removed by a worm screw, for example. A portion of the incombustible solids are subsequently screened to remove the non-combustible material and any agglomerations that can form during the combustion of the waste fuel and returned to the fluidized bed within the fluidized bed reactor 12 at a rate required to maintain the inventory of the bed make-up material.

[0043] The combustor air bar grid 1 comprises a number of (generally, at least two, but three, four, five, . . . , are possible) main air collector bars 2 in fluid communication with a source 9 of pressurized fluidizing gas. In this manner, the distribution of the fluidizing gas can be made more uniform.

[0044] The combustor air bar grid further comprises a plurality of primary air bars 3 that are transverse to the main air collector bars 2 and arranged on the at least two main air collector bars 2 such that the main air collector bars 2 support them, and in fluid communication to at least two of the main air collector bars 2, and a plurality of fluidizing nozzles 4 arranged to each of the primary air bars 3 for fluidizing the fluidized bed reactor 12. The fluidizing nozzles 4 may be arranged on central air conduits 4B located on each of the primary air bars 3, or directly on primary air bars 3.

[0045] The main air collector bars 2 are in fluid communication with the primary air bars 3 via openings between the collector bars 2 and the primary air bars 3. The openings are preferably manufactured before installing the primary air bars 3 on the main air collector bars 2 such that the openings have been made (such as by cutting or laser cutting) at overlapping locations at the primary air bars 3 and the main air collector bars 2.

[0046] The main air collector bars 2 create a wind box that is connected with boiler pressure parts using at least one expansion joint.

[0047] The combustor air bar grid 1 may further comprise a number of support beams or support bars 5 arranged to support the main air collector bars 2 such that the support beam or support bars 5 form a frame structure, in which, preferably, the support bars 5 are arranged as vertical pillars directly under the main air collector bars, optionally, with an essentially horizontal frame structure 5c.

[0048] The whole weight of fluidized bed and bottom ash may be transferred from the primary air bars via the main air collector beams (that can be realized as welded plate beams) to the grid supporting structure.

[0049] The combustor air bar grid 1 comprises a number of ash hoppers 6 arranged beneath the ash removal openings defined by the main air collector bars 2 and primary air bars 3. Preferably, the ash hoppers 6 are laterally aligned with and in mechanical contact with the main air collector bars 2.

[0050] During the descent of the spent bed material through the plenum, heat is continuously transferred from the bed material to the water flowing through the tubes forming the reactor walls (front wall 24a, rear wall 24b, and side walls), and the ash hopper 6 walls. The main air collector bars 2 form air-cooled external walls for the ash hoppers 6. Thus, the ash hoppers 6 do not necessarily need to be water-cooled. The lower part of the ash hoppers 6 may thus be made conical and without employing the cooled plate design.

[0051] Then, preferably, the main air collector bars 2 are configured to air cool the ash hoppers 6 with the pressurized fluidizing gas from the main air collector bars 2, most preferably, via air nozzles or pipes.

[0052] The at least two main air collector bars 2 and the primary air bars 3 are preferably beams of metal, forming conduits for the fluidizing gas.

[0053] The combustor air bar grid 1 may be constructed as a modular combustor air bar grid consisting of a number of modules 7, such that in the modules 7 the main air collector bars 2 have a length allowed for normal road transport or for an abnormal or oversize load, preferably, between 2.5 and 4 meters, most preferably between 2.50/2.55/2.60 and 3.50 meters, the maximum allowed dimensions currently varying in each country.

[0054] Alternatively, or, in addition to this, the main air collector bars 2 may consist of segments composed of modules 7 joined together. The modules 7 each may have a length allowed for normal road transport or for an abnormal or oversize load, preferably, between 2.5 and 4 metres meters, most preferably between 2.5/2.55/2.60 and 3.5 meters.

[0055] FIG. 1 shows a steam generator system 10 that has a circulating fluidized bed reactor as its fluidized bed reactor 12, and FIGS. 2 and 3 illustrate the combustor air bar grid 1 located within the circulating fluidized bed reactor. Alternatively, the combustor air bar grid 1 can be located within a bubbling fluidized bed reactor as shown in FIG. 4.

[0056] It is obvious to the skilled person that, along with the technical progress, the basic idea of the invention can be implemented in many ways. The invention and its embodiments are thus not limited to the examples described above, but they may vary within the contents of patent claims and their legal equivalents.

[0057] While the invention has been described herein by way of examples in connection with what are at present considered to be the most preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various combinations or modifications of its features and several other applications included within the scope of the invention as defined in the appended claims.