Combustion device air bar grate used in a fluidized bed reactor and fluidized bed reactor

Abstract

A combustor air bar grid (1) for use in a fluidized bed reactor (12) includes at least two main air collector bars (2) in fluid communication with a source of fluidizing gas, a plurality of primary air bars (3) transverse to the main air collector bars (2) and disposed on the at least two main air collector bars (2) so that the main air collector bars (2) support the primary air bars, the plurality of primary air bars being in fluid communication with at least two of the main air collector bars (2), the main air collector bars (2) and the primary air bars (3) defining ash removal openings in the air bar grid (1), and a plurality of fluidizing nozzles (4) disposed on each of the primary air bars (3) for fluidizing the bed reactor (12). This patent application also includes an independent claim for a fluidized bed reactor.

Description

Technical Field

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[0001] The present invention relates to an improved combustion apparatus air bar grid, and more particularly to a fluidized bed reactor for the combustion of solid materials containing, for example, biomass or the incineration of waste fuels containing non-combustible materials and for the removal of ash or non-combustible materials during combustion or incineration.

Background Art

[0002] Chemical reactions such as combustion or gasification are carried out in a fluidized bed material layer of a fluidized bed reactor, usually a so-called bubble fluidized bed reactor or a circulating fluidized bed reactor. There, a fluidizing gas, such as air, is supplied into the reactor through the fluidized bed material layer mainly comprising sand and fuel so that the bed changes to an easily movable fluid state. However, in a fluidized bed reactor, the materials to be combusted are non-uniform and may agglomerate or incorporate non-combustible materials.

[0003] The present invention relates to an improved combustion apparatus air bar grid, and more particularly to a fluidized bed reactor for the combustion of solid materials containing, for example, biomass or the incineration of waste fuels containing non-combustible materials and for the removal of ash or non-combustible materials during combustion or incineration. Combustion apparatus air bar grids have been designed to allow air to flow upward through the combustion bed of the material and to allow ash and non-combustible materials to be removed from the bottom of the bed. Ash and non-combustible materials as well as the bed material pass through the spaces between the bars. This type of grate may have an air manifold that distributes air to individual bars connected to the manifold. Each air bar has an air nozzle for dispersing the fluidizing air into the bed material

[0004] <00000l5>U.S. Patent No. 4,402,665 discloses an air bar grid used in a fluidized bed reactor. The air bar grid includes a main air collector in fluid communication with a source of pressurized air and a grid of primary air bars perpendicular to the main air collector. Each of the primary air bars has an upper surface and is connected to the main air collector so as to be in fluid communication along its length. Intermediate air bars are disposed parallel to the main air collector and perpendicular to each of the primary air bars. The intermediate air bars and the primary air bars are in the same plane and intersect at right angles to each other.

[0005] U.S. Patent No. 5,743,197 discloses a grate assembly for a fluidized bed boiler having a water-cooled, steam-cooled, or air-cooled diffuser tube grate. The diffusers to be cooled are supported at their ends by tubes that conduct water, steam, or air. The diffusers are installed side by side such that horizontal apertures extending longitudinally between adjacent diffusers remain.

[0006] U.S. Patent No. 5,425,331 discloses a fluidized bed reactor having a hollow separation air bar located at the bottom of a boiler to support a bed of particulate material including fuel and non-combustible solids. The air bar is supported at the bottom of the reactor by a plurality of water-cooled support tubes that continuously transfer heat from the air bar to water flowing through the tubes. The air bar extends perpendicularly to and is in airflow communication with a plenum chamber located outside the hopper and adjacent to the wall. Pressurized air is introduced into the chamber by conventional means.

[0007] Korean Published Patent No. 2009 / 132934A (KR2009 / 132934A) discloses an air distributor system for a waste solid fuel combustion system including a fluidized bed. The air distributor system comprises an air supply pipe, a nozzle, and a cooling water pipe. The air supply pipe is connected to the air distributor in the longitudinal and transverse directions. The air supply pipe is equipped with a nozzle connector having multiple air supply ports. The cooling water pipe is installed outside the air supply pipe and supplies cooling water to prevent thermal corrosion of the air supply pipe.

[0008] U.S. Patent No. 5,368,824 discloses a gas distribution system employing an array of parallel gas inlet pipes and a pair of transverse gas inlet pipes located below the first group of pipes for fluidizing a granular bed in a reaction vessel and for removing non-fluidizable particles that may be introduced into or formed in the bed.

[0009] Soviet Patent No. 1149105 discloses a fluidized bed furnace, which includes a combustion chamber, below which an airbox is located, and inside which an ash hopper is installed. Above the ash hopper is an air supply pipe whose end is connected to the box cavity, and at least one pipe connected to the cavity of the air supply pipe and the cavity of the airbox.

[0010] U.S. Patent Application Publication No. 2003 / 170582A1 discloses a tube grate for a fluidized bed boiler. Air is supplied to the fluidized bed boiler through several tubes. The active region of the grate, where the supply of air and other elements to the tube grate is provided, is regulated by tube-specific control means included in at least some of the tubes of the tube grate. [Overview of the project]

[0011] This invention the purpose The first objective is to improve the collection of ash and non-combustible materials in a fluidized bed reactor. The second objective of the present invention is to enable a more homogeneous flow of fluidizing gas in the bed. Both objectives are based on the combustion apparatus air bar grid described in independent claim 1 and the parallel independent claims. 12 This can be achieved by the fluidized bed reactor described above.

[0012] The dependent claims describe advantageous embodiments of a combustion device air bar grid.

[0013] A combustion device air bar grid used in a fluidized bed reactor comprises at least two main air collector bars that are in fluid communication with a source of pressurized fluidizing gas (such as air), and a plurality of primary air bars that are lateral to the main air collector bars and arranged on at least two of the main air collector bars such that at least two of the main air collector bars support the plurality of primary air bars, and that are in fluid communication with at least two of the main air collector bars. The main air collector bars and primary air bars define the ash removal openings of the air bar grid. The combustion device air bar grid further comprises a plurality of fluidizing nozzles arranged on each of the primary air bars to fluidize the bed reactor.

[0014] Compared to the combustion device air bar grids known from U.S. Patent No. 4,402,665, the structure of this fluidized bed reactor can be simplified by introducing pressurized fluidizing gas into the primary air bars from at least two of the main air collector bars, i.e., from different locations along the main air bars. On the one hand, this makes it possible to have a more uniform pressure distribution of pressurized fluidizing gas along its length within the primary air bars. On the other hand, the main air collector bars also function as support beams for the primary air bars, thereby enabling a grid module design. Furthermore, the supply air ducts also act as support beams, enabling a grid module design.

[0015] Furthermore, compared to known grate bar assemblies from U.S. Patents 5,743,197 and 5,425,331, the structure of this fluidized bed reactor can be simplified by flowing the same medium in the primary air bar through two main air collector bars supporting the primary air bar. Thus, the supply of the medium entering the fluidized bed reactor can be implemented more compactly.

[0016] The pressurized fluidizing gas helps to cool not only the primary air bars but also the main air collector bars, maintaining them within an appropriate temperature range and thus ensuring that the primary air bars and main air collector bars do not soften excessively. By appropriately sizing the main air collector bars and the spacing between adjacent main air collector bars, the weakening of the combustion device air bar grid caused by the softening of the primary air bars can be mitigated. A further advantage is that the main air collector bars are cooled by air, which helps to simplify the mechanical design of the reactor because the structure for water cooling of the main air collector bars can be omitted.

[0017] In its simplest form, the main air collector bar is in fluid communication with the primary air bars through overlapping fluidizing gas transfer openings fabricated on the upper side of each collector bar and on the lower side of each primary air bar. Particularly preferable, the fluidizing gas transfer openings are fabricated as cutouts in the opposing surfaces of the main air collector bar and the primary air bar at their intersection, and both bars have a rectangular cross-section. This allows for relatively minimal structural weakening due to the cutouts compared to the deep cutouts in air ducts with a circular cross-section, as known from U.S. Patent No. 4,402,665.

[0018] The combustion device air bar grid may further include several support beams or support bars positioned to support the main air collector bar. In this way, the weight of the floor can be substantially supported by the support beams or support bars, which simplifies the mechanical configuration of the fluidized bed reactor.

[0019] The combustion device air bar grid preferably further comprises several ash hoppers positioned below the ash removal opening formed by the main air collector bar and primary air bars. This allows for the effective collection of ash and non-combustible materials from the floor.

[0020] The upper part of the ash hopper is aligned laterally with and mechanically in contact with the main air collector bar. According to one embodiment of the present invention, the upper part of the ash hopper has an upper section having a rectangular horizontal cross-section, and the two opposing sides of the upper part of the ash hopper are attached to the main air collector bar, for example, by welding the top of the ash hopper funnel to the main air collector bar, so as to be in mechanical contact with the main air collector bar. The main air collector bar thus forms the air-cooled outer wall of the ash hopper.

[0021] Furthermore, the main air collector bar creates a wind box, which can be connected to the boiler pressure components using at least one expansion joint. Thus, the lower part of the ash hopper can be constructed in a conical shape without requiring the use of a cooling plate design. The total weight of the fluidized bed and bottom ash can be transferred from the distribution beams on the main air collector bar and primary air bar (preferably welded plate beams) to the grid support structure.

[0022] Connecting the main air collector bar to the boiler pressure components using at least one expansion joint helps to accommodate thermal expansion.

[0023] The main air collector bar is configured to form an external air-cooled wall for the ash hopper, which is cooled by pressurized fluidizing gas. ru In this way, the pressurized fluidizing gas from the main air collector bar can also be used to remove heat from the ash hopper. This eliminates the need to use air-cooled or water-cooled plates in the ash hopper.

[0024] Preferably, at least two main air collector bars and a plurality of primary air bars are hollow metal beams that form conduits for the fluidizing gas.

[0025] The combustion device air bar grid may be configured as a modular combustion device air bar grid consisting of several modules. Therefore, in the module, the main air collector bar has a length that can be transported by normal railway or road, or a length that allows irregular or extra-large loading, preferably 2.5 to 4 meters, and most preferably 2.50 / 2.55 / 2.60 to 3.50 meters. Such a combustion device air bar grid is easier to transport to the installation site.

[0026] According to another advantageous aspect, the main air collector bar may be composed of segments consisting of joined modules. This makes it possible to configure the modular fluidized bed reactor in a modular manner. In particular, each module may have a length that can be transported by normal road, or a length that allows irregular or extra-large loading, preferably 2.5 to 4 meters, and most preferably 2.50 / 2.55 / 2.60 to 3.50 meters.

[0027] The fluidized bed reactor includes a furnace having a combustion device air bar grid according to the first aspect of the present invention.

Brief Description of the Drawings

[0028] Hereinafter, the combustion device air bar grid and the fluidized bed reactor will be described in more detail with reference to the exemplary embodiments shown in FIGS. 1 to 4.

[0029] [Figure 1] A steam generation device system including a circulating fluidized bed reactor is shown. [Figure 2] It is a side view of the combustion device air bar grid. [Figure 3] It is an end view of the combustion device air bar grid of FIG. 2. [Figure 4] It is a bubble fluidized bed reactor boiler equipped with a combustion device air grid according to the present invention.

[0030] In all the figures, the same reference numerals refer to the same technical features.

Embodiments for Carrying Out the Invention

[0031] Figure 1 shows a steam generation system 10. The structure and operation of the steam generation system 10, including the combustion device air grate 1, ash hopper 6, and support structure, may be identical to the steam generation system 10 disclosed in U.S. Patent No. 5,425,331, which is incorporated herein by reference.

[0032] The steam generation system 10 includes a fluidized bed reactor 12 (shown as a circulating fluidized bed reactor in Figure 1 and as a bubble fluidized bed reactor in Figure 4), a cyclone separator 14, and a heat recovery area 16.

[0033] The air bar grid 1 is located at the bottom of the fluidized bed reactor 12 and will be described in detail below with reference to the embodiments shown in Figures 2 and 3.

[0034] The cyclone separator 14 receives a mixture of air and combustion gas products from the fluidized bed reactor 12, along with any mixed solid particles. The separator 14 operates to separate the solid from the gas, which is then passed to the heat recovery region 16. The solid from the separator 14 falls into the tapered section 14a of the separator and is reinjected into the lower part of the reactor compartment 12 via the return leg 22. The gas passes through the heat recovery region 16 and exits through the outlet conduit 16a.

[0035] 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 Figure 1) that extend perpendicularly to the front and rear walls to form the housing.

[0036] At least one distributor 27 extending through the front wall 24a, the rear wall 24b, or the side wall for introducing fuel into the fluidized bed may be used to supply fuel into the fluidized bed reactor 12, as shown in Figure 1. Alternatively or additionally, fuel may be supplied by a silo hopper and screw feeder located above the fluidized bed reactor 12, and by a register located above the combustion device air bar grid 1, having an opening formed in the lid for introducing waste fuel such as biomass or municipal solid waste onto the upper surface of the fluidized bed. The waste fuel may include non-combustible materials such as bottles and cans.

[0037] A distributor 28 for introducing bed make-up material onto the top surface of the fluidized bed extends through the front wall 24a. This bed make-up material generally consists of sand and / or limestone or dolomite to absorb sulfur oxides released during the combustion of waste fuel. It is understood that other distributors may be associated with walls 24a, 24b and either or both of the side walls to distribute the bed make-up material onto the bed as needed.

[0038] When the steam generator 10 is in operation, a certain amount of biomass or waste fuel and floor material are introduced through the screw feeder 27 and distributor 28, respectively, and pile up on the upper surface of the air grate 1. Fluidizing gas—preferably air—from an external source is supplied to the plenum chamber 49 in sufficient volume by the fluidizing gas source 9. Preferably, combustion fluidizing air is used as the fluidizing gas. The pressurized fluidizing gas fluidizes the floor material above the combustion device air bar grate 1 in the furnace 26. A burner (not shown) is provided in the plenum chamber 49 to raise the temperature of the fluidizing gas to a temperature sufficient to start combustion of the biomass or waste fuel material placed above the combustion device air bar grate 1. If the biomass or waste fuel has a low calorific value, an auxiliary fuel such as coal may be provided by the distributor 28. Once the biomass or waste fuel inside the reactor 12 has started to burn with the fluidizing gas, ignition by the burner and / or auxiliary fuel is reduced or stopped as needed.

[0039] As combustion progresses, additional waste fuel and floor components are introduced into the fluidized bed reactor 12 through a screw feeder 27 and a distributor 28, respectively. Non-combustible materials, ash, and used floor components are carried downward by gravity and air as the fluidizing gas and combustion products move upward within the fluidized bed reactor 12. The non-combustible solids move downward through the fluidized bed reactor 12 to the upper surface of the combustion device air bar grid 1, pass downward through the openings in the air bar grid 1, and continue to descend within the ash hopper 6 as heat is transferred from the floor material by convection due to the fluidizing gas flowing from the air nozzles or pipes along with the air from the primary air bars, thereby air-cooling the outer wall of the ash hopper 6. The non-combustible solids exit through an opening at the base of the hopper 6 and are removed, for example, by a worm screw. A portion of the non-combustible solid is then sieved to remove any aggregates that may form during the combustion of the non-combustible material and waste fuel, and returned to the fluidized bed in the fluidized bed reactor 12 at a rate necessary to maintain the stock of bed constituent materials.

[0040] The combustion device air bar grid 1 is equipped with several (generally at least two, but three, four, five, ...) main air collector bars 2 that are in fluid communication with a pressurized fluidizing gas source 9. This allows for a more uniform distribution of the fluidizing gas.

[0041] The combustion device air bar grid further comprises a plurality of primary air bars 3, which are lateral to the main air collector bar 2 and are arranged on at least two of the main air collector bars 2 such that the main air collector bar 2 supports the primary air bars, and which are in fluid communication with at least two of the main air collector bars 2; and a plurality of fluidizing nozzles 4, which are arranged on each of the primary air bars 3 to fluidize the fluidized bed reactor 12. The fluidizing nozzles 4 may be arranged on a central air conduit 4B located above each of the primary air bars 3, or they may be arranged directly on the primary air bars 3.

[0042] The main air collector bar 2 is in fluid communication with the primary air bar 3 through an opening between the collector bar 2 and the primary air bar 3. The opening is preferably created before the primary air bar 3 is installed on the main air collector bar 2, such that the opening is already formed (for example, by cutting or laser cutting) at the location where the primary air bar 3 and the main air collector bar 2 overlap.

[0043] The main air collector bar 2 creates a wind box, which is connected to the boiler pressure component using at least one telescopic joint.

[0044] The combustion device air bar grid 1 may further include several support beams or support bars 5 arranged to support the main air collector bar 2, thereby forming a frame structure, and the support bars 5 are preferably arranged within this frame structure as vertical columns directly below the main air collector bar, and optionally together with a substantially horizontal frame structure 5c.

[0045] The total weight of the fluidized bed and bottom ash can be transferred from the primary air bar to the grid support structure via the main air collector beam (which can be implemented as a welded plate beam).

[0046] The combustion device air bar grid 1 comprises several ash hoppers 6 positioned below the ash removal opening defined by the main air collector bar 2 and the primary air bar 3. Preferably, the ash hoppers 6 are aligned laterally with and in mechanical contact with the main air collector bar 2.

[0047] As the used floor material descends through the plenum, heat is continuously transferred from the floor material to the reactor walls (front wall 24a, rear wall 24b, and side walls) and to the water flowing through the pipes that form the walls of the ash hopper 6. The main air collector bar 2 forms the air-cooled outer wall of the ash hopper 6. Thus, the ash hopper 6 does not necessarily need to be water-cooled. Therefore, the lower part of the ash hopper 6 may be manufactured in a conical shape and without employing a cooling plate design.

[0048] In that case, preferably, the main air collector bar 2 is configured to air-cool the ash hopper 6 with pressurized fluidized gas from the main air collector bar 2, most preferably via an air nozzle or pipe.

[0049] At least two main air collector bars 2 and a plurality of primary air bars 3 are preferably metal beams and form conduits for the fluidizing gas.

[0050] The combustion device air bar grid 1 may be configured as a modular combustion device air bar grid consisting of several modules 7, and in each module 7, the main air collector bar 2 has a length that allows for normal road transport or an irregular or oversized load, preferably 2.5 to 4 meters, most preferably 2.50 / 2.55 / 2.60 to 3.50 meters, although the maximum permissible dimensions are currently varying from country to country.

[0051] Alternatively, or in addition to the above, the main air collector bar 2 may consist of segments made up of joined modules 7. Each module 7 may have a length suitable for normal road transport or for irregular or oversized loads, preferably 2.5 to 4 meters, most preferably 2.50 / 2.55 / 2.60 to 3.50 meters.

[0052] Figure 1 shows a steam generator system 10 having a circulating fluidized bed reactor as the fluidized bed reactor 12, and Figures 2 and 3 illustrate the combustion device air bar grid 1 located within the circulating fluidized bed reactor. Alternatively, the combustion device air bar grid 1 may be located within a bubble fluidized bed reactor, as shown in Figure 4.

[0053] Those skilled in the art will see that, with technological advancements, the basic concept of the present invention can be implemented in many ways. Therefore, the present invention and its embodiments are not limited to the examples described above and may vary within the scope of the claims and their legal equivalents.

Claims

1. A combustor air bar grid (1) for use in a fluidized bed reactor (12), comprising: at least two main air collector bars (2) in fluid communication with a source of fluidizing gas; a plurality of primary air bars (3) transverse to the main air collector bars (2), disposed on the at least two main air collector bars (2) such that the main air collector bars (2) support the primary air bars, and in fluid communication with at least two of the main air collector bars (2), the main air collector bars (2) and the primary air bars (3) defining ash removal openings in the air bar grid (1); a plurality of fluidization nozzles (4) disposed in each of the primary air bars (3) for fluidizing the bed reactor (12); A combustion device air bar grid (1) comprising:

2. 2. The combustion device air bar grid (1) of claim 1, wherein the main air collector bars (2) are in fluid communication with the primary air bars (3) through overlapping fluidization gas transfer openings made on the upper side of each collector bar (2) and on the lower side of each primary air bar (3).

3. 3. The combustion device air bar grid (1) according to claim 1 or 2, further comprising several support beams or bars (5, 5c) arranged to support the main air collector bar (2), among which vertical support beams or bars (5) are arranged directly below the main air collector bar (2), optionally together with a substantially horizontal framework (5c).

4. Combustor air bar grate (1) according to any one of claims 1 to 3, further comprising several ash hoppers (6) arranged below the ash removal opening.

5. 5. The combustor air bar grate (1) according to claim 4, wherein the upper part of the ash hopper (6) is laterally aligned with and in mechanical contact with the main air collector bar (2).

6. 6. Combustor air bar grid (1) according to claim 4 or 5, wherein the main air collector bar (2) is connected to the boiler pressure part by using at least one expansion joint.

7. 7. The combustion device air bar grid (1) according to claim 6, wherein the main air collector bar (2) is configured to form an external air-cooled wall for the ash hopper (6) that is cooled by the pressurized fluidizing gas.

8. 8. The combustion device air bar grid (1) according to any one of claims 1 to 7, wherein the at least two main air collector bars (2) and the plurality of primary air bars (3) are hollow metal beams and form conduits for the fluidizing gas.

9. 10. A combustor air bar grid (1) configured as a modular combustor air bar grid consisting of several modules (7) formed by combustor air bar grids according to any one of claims 1 to 8, whereby in each module (7) the main air collector bars (2) have a length that allows for normal rail or road transport or a length that allows for irregular or oversized loads, preferably between 2.5 and 4 meters, most preferably between 2.50 / 2.55 / 2.60 and 3.50 meters.

10. 10. Combustor air bar grid (1) according to claim 9, wherein the main air collector bar (2) is made up of segments made up of modules (7) joined together preferably by welding.

11. 11. Combustion device air bar grating (1) according to claim 9 or 10, wherein the modules (7) each have a length that allows for normal road transport or a length that allows for irregular or oversized loads, preferably between 2.5 and 4 metres, most preferably between 2.50 / 2.55 / 2.60 and 3.50 metres.

12. 12. The combustion device air bar grid (1) according to any one of claims 1 to 11, wherein the main air collector bar (2) and the primary air bar (3) comprise hollow passages for the pressurized fluidizing gas.

13. 13. The combustion device air bar grid (1) according to claim 12, wherein the combustion device air bar grid (1) has openings for connecting the hollow passages of the main air collector bar (2) and the primary air bar (3) to the main air collector bar (2) and the primary air bar (3), and the openings are arranged at overlapping locations of the primary air bar (3) and the main air collector bar (2).

14. A fluidized bed reactor (12) comprising a furnace (26a) having a combustor air bar grate (1) according to any one of claims 1 to 13.

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