FLUIDIZED BED HEAT EXCHANGER

Abstract

Fluidized bed heat exchanger with a chamber (24), comprising at least one solid particles inlet port (22) at least one solid particles outlet port (30), arranged at a distance to the at least one inlet port (22), means (46) for introducing a fluidizing gas from a bottom area (24b) of said chamber (24) into said chamber (24), wall-like heat transfer means (28) in its lower part, extending in a main flow direction of the solid particles on their way from the inlet port (22) to the outlet port (30), substantially parallel to each other, with a space (C) between adjacent heat transfer means (28), at least one baffle (50,52) in its upper part, extending substantially perpendicular to the heat transfer means (28), downwardly from a chamber ceiling (24c), with its lower end at a distance to the heat transfer means (28) and comprising extensions (E), protruding into the space (C) between adjacent heat transfer means (28), and couplings (B) to mechanically connect the said heat transfer means (28) to said extensions (E).

Claims

1. Fluidized bed heat exchanger with a chamber (24), comprising 1.1 at least one solid particles inlet port (22) 1.2 at least one solid particles outlet port (30), arranged at a distance to the at least one inlet port (22), 1.3 means (46) for introducing a fluidizing gas from a bottom area (24b) of said chamber (24) into said chamber (24), 1.4 wall-like heat transfer means (28) in its lower part, extending 1.4.1 in a main flow direction of the solid particles on their way from the inlet port (22) to the outlet port (30), 1.4.2 substantially parallel to each other, 1.4.3 with a space (C) between adjacent heat transfer means (28), 1.5 at least one baffle (50,52) in its upper part, extending 1.5.1 substantially perpendicular to the heat transfer means (28), 1.5.2 downwardly from a chamber ceiling (24c), 1.5.3 with its lower end at a distance to the heat transfer means (28) and comprising 1.5.4 extensions (E), protruding into the space (C) between adjacent heat transfer means (28), and 1.6 couplings (B) to mechanically connect the said heat transfer means (28) to said extensions (E).

2. Fluidized bed heat exchanger according to claim 1, wherein the at least one baffle (50, 52) has at least one opening (O) to allow pressure adjusting.

3. Fluidized bed heat exchanger according to claim 1, wherein the at least one baffle (50, 52) is designed as a curtain with numerous small, discrete openings.

4. Fluidized bed heat exchanger according to claim 1, wherein the at least one baffle (50, 52) extends between opposite walls (24s) of the chamber (24).

5. Fluidized bed heat exchanger according to claim 1, wherein the at least one baffle (50, 52) is made of pressure pipes (PP) to transport water of 270° C. to 400° C. at 90 bar to 320 bar.

6. Fluidized bed heat exchanger according to claim 1, wherein the pressure pipes (PP) of each baffle (50, 52) are connected to a central feeding line (CFL).

7. Fluidized bed heat exchanger according to claim 1, with multiple baffles (50, 52), arranged parallel to each other at different distances to the inlet port (22).

8. Fluidized bed heat exchanger according to claim 1, wherein the heat transfer means (28) are designed as heat exchange tubes (ET) for conveying a heat transfer medium and arranged in a meandering fashion, thereby providing a vertically oriented wall-like pattern.

9. Fluidized bed heat exchanger according to claim 1, wherein the heat transfer means (28) are designed as heat exchange tubes (ET) to transport steam of 300° C. to 650° C. at 80 bar to 300 bar.

10. Fluidized bed heat exchanger according to claim 1, wherein the heat transfer means (28) are designed as heat exchange tubes (ET) which are connected to a central feeding tube (42, 44).

11. Fluidized bed heat exchanger according to claim 1, wherein the heat transfer means (28) and the baffles (50, 52), including their extensions (E), form a three-dimensional grid-like structure.

12. Fluidized bed heat exchanger according to claim 1, wherein the heat transfer means (28) and the baffles (50, 52) are arranged at about 90 degrees to each other.

13. Fluidized bed heat exchanger according to claim 1 with chamber walls (14w, 24w, 24s) being at least partially water-cooled.

14. Fluidized bed heat exchanger according to claim 13 with said chamber walls (14w, 24w, 24s) are made of pressure tubes, with fins between adjacent pressure tubes.

Description

[0072] The invention is now described with reference to the attached drawing, showing—all in a very schematic way—in

[0073] FIG. 1

[0074] A general concept of a fluidized bed apparatus

[0075] FIG. 2

[0076] A cross sectional view of a fluidized bed heat exchanger

[0077] FIG. 3

[0078] A top view on the FBHE 24 of FIG. 2 along line 3-3

[0079] FIG. 4

[0080] A three dimensional view of the arrangement of heat transfer means and baffles in an FBHE

[0081] FIG. 5

[0082] A three dimensional view of a coupling between a baffle extension and adjacent heat transfer tubes of heat transfer means

[0083] In the Figures identical and similar acting construction parts are identified by same numerals.

[0084] FIG. 1 discloses the general concept of a fluidized bed apparatus and its main components according to the present invention.

[0085] It comprises: [0086] A circulating fluidized bed reactor (CFBR) 10. Its lower part comprises a grate-like structure 12 through which air (arrow A1) is blown into a reactor chamber 14 via (not shown) nozzles, thus providing a fluidized bed (denseboard—DB—) above said grate 12, wherein said denseboard comprises a particulate material like coal, wood etc. to be burnt. [0087] The CFBR has two outlet ports 16 at opposite sides of its upper part, allowing a mixture of gas and solid particles exhausted from the CFBR to flow into associated separators 18, namely cyclone separators. The separators serve to separate solid particles from the gas. [0088] Transfer means 20, designed as ducts, extend from the lower end of each separator 18 downwardly and into an inlet port 22 along the ceiling 24c of a fluidized bed heat exchanger (FBHE) 24. [0089] A syphon-like tube construction 26 (U-shaped) extends from the lower end of each separator 18 into reactor chamber 14 and enters into chamber 14 shortly above grate 12 of said CFBR. [0090] The FBHE is equipped with (plate-like) heat transfer means 28 and an outlet port 30 merging into reactor chamber 14 at the same vertical height as tube construction 26.

[0091] This concept belongs to prior art. Insofar details are not further illustrated as known to the skilled person.

[0092] The invention includes one or more of the following features:

[0093] According to FIG. 2 the fluidized bed heat exchanger 24 displays an inlet port 22 at its upper end (in FIG. 2: top left) and an outlet port 30 at its upper end (in FIG. 2: top right), i. e. opposite to each other. Said outlet port 30 provides return means for solid particles which are further transported along a transfer duct into chamber 14. A common wall 14w of chamber 14 and FBHE 24 is also displayed.

[0094] Outlet port 30 comprises multiple flow through openings, arranged in a horizontal row with a distance to each other along a corresponding wall section of said wall 14w.

[0095] Said wall 14w is water-cooled, namely constructed of vertically extending tubes with fins running between adjacent tubes. The tubes are cooled by water fed through said tubes.

[0096] The through holes having the function of discrete outlet ports are shown in FIG. 2 in a slightly inclined orientation, with a lower end towards the fluidized bed heat exchanger 24 and a higher end towards the fluidized bed reactor chamber 14.

[0097] This inclined orientation (sloped outlet port 30) can be provided as part of a 3-dimensional profile (for example as a convexity 14w′) of said wall 14w towards the inner space/chamber of the fluidized bed heat exchanger 24 as shown in dotted lines in FIG. 2 and characterized by numeral 30′.

[0098] FIGS. 2 to 4 display the design and construction of a type of heat transfer means 28 within the fluidized bed heat exchanger 24. In FIG. 2 only one of said heat transfer means is shown. Further heat transfer means of equal design are placed at a distance to each other within FBHE 24 (perpendicular to the plane of projection), as schematically shown in FIG. 4.

[0099] Steam is fed into said means 28 via a central feeding line 42, then flowing through the meandering tube (as shown), representing said means 28, and escaping via a common outlet line 44, allowing to take heat from the particulate material (symbolized by dots P) moving through FBHE 24 between inlet port 22 and outlet port 30.

[0100] It is important that each of said means 28 is designed in a wall-like pattern and extending substantially parallel to the main flow direction of the solid particles on their way to and through the outlet port 30, symbolized in FIG. 2 by arrow S.

[0101] All tubes 28 are connected to the same feeding line 42 and outlet line 44.

[0102] The meandering tubes not only give the heat transfer means 28 a wall-like pattern but as well a grate-like structure to allow the particulate material to pass through as well in another horizontal direction, although to much less extent.

[0103] The horizontally extending sections of said tubes are about ten times longer than the vertically extending sections (FIG. 2 is not drawn to scale). Adjacent horizontal sections extent to a distance to each other being about the tube diameter.

[0104] As shown in FIGS. 2,4 the heat transfer means 28 extent about more than 60% of the chamber height, being the distance between a chamber bottom 24b and a chamber sealing 24c. In the embodiment each of said wall-like heat transfer means 28 extends from slightly above bottom 24b (or more precisely: from slightly above air nozzles 46, arranged in said bottom 24b, see FIG. 2) to slightly below inlet port 22 and from slightly off wall 14w to slightly off opposite wall 24w.

[0105] In prior art devices a separate entrance chamber with a discrete partition wall is constructed between wall 24w and an adjacent part of heat transfer means 28 as well as a separate return chamber between wall 14w and parts 28. These walls and chambers caused the stream of solid particles to flow up and down which is now avoided with the new design without any partition walls, which make the construction simpler, cheaper and more effective.

[0106] The particulate material may take a direct way from the inlet port 22 to the outlet port 30 (see arrow S) along the channels/gaps C formed between adjacent tubes (heat transfer means), as may be seen in FIG. 3.

[0107] Fluidization of the particulate material within FBHE 24 is achieved by said air nozzles 46 in the bottom area 24b. The particulate material is circulated by said purging means within FBHE 24 in order to optimize heat transfer from the hot solid particles P into the steam flowing within tube like heat transfer means 28 at a temperature of typically 300-625° C. and a pressure of between 80 and 300 bar.

[0108] Back to FIG. 2: The embodiment displayed further includes two baffles 50, 52, which extent from ceiling 24c downwardly, ending shortly above heat transfer means 28. These baffles 50, 52 extend substantially perpendicular to a straight line between inlet port 22 and outlet port 30 (dotted line L), i.e. perpendicular to the wall like heat transfer means 28.

[0109] Both baffles 50, 52 extend between opposite walls of FBHE 24 (only one, namely 24s is shown), being the walls bridging said walls 14w, 24w. The baffles 50, 52 are arranged at a distance to each other.

[0110] Each of said baffles 50, 52 comprise one opening O (see FIG. 4) to allow pressure adjustment (equalization) within the inner space of FBHE 24.

[0111] The said baffle(s) 50, 52 are further designed like a curtain, made of pipes, through which water of 270-374° C. at 90-320 bar is fed.

[0112] The baffles 50,52 urge the particulate material, flowing into chamber 10 via inlet port 22, to move downwardly (see arrow S) at baffle 50 and then to flow through said channels C (FIGS. 3,4) between adjacent heat transfer means 28 on their way between inlet port 22 and outlet port 30.

[0113] FIG. 4 shown the meandering wall like structure of heat transfer means (tubes) 28, again only schematically for better illustration. In view of the size of an industrial FBHE and the amount of solid material passing there through the skilled person will design the exact number, size and arrangement of heat transfer means 28, baffles 50,52, air nozzles 46 etc. in accordance with the specific demand.

[0114] FIG. 4,5 further display pipe-like extensions E, extending from the respective baffle 50,52 downwardly and into the spaces C between adjacent heat transfer means 28. The extensions E are in fluid communication with a central feeding line CFL to which pressure pipes PP are connected, which define the corresponding baffle 50,52. Each baffle 50,52 is made of one or more of such pressure pipes PP, arranged similarly as the heat exchange tubes ET of heat transfer means 28 to allow water of 270-400° C. and 90-320 bar pressure passing there through.

[0115] These extension pipes E are equipped with couplings B, shaped as brackets, as may be seen from FIG. 5. Each bracket/coupling B has a beam-like design with 3 openings through which 2 corresponding tube sections of a heat exchange tube ET and one section of a corresponding pipe extension E extend. For fitting, the said brackets B are made of steel half shelves, laid around the corresponding pipe/tube and then closed by a screw, bolt, clamp or the like.

[0116] It may be seen from FIG. 5 that the diameter of each pipe extension E is about 20% of the distance (width of channel C) between adjacent all like heat transfer means 28.

[0117] At the same time these extensions E and brackets B allow the mechanically integral and crosswise arrangement of heat transfer means 28 and baffles 50,52 within chamber 24.