The invention relates to so-called Circulating Fluidized Bed Apparatus (CFBA) and its components, in particular
Numerous designs of such apparatus and components have been developed over the past decades.
Nevertheless there is a continuous demand for improvements, especially with respect to energy efficiency (typical capacity range: 50-600 MW—electrical—), effectiveness, simple construction, avoidance of mechanical and thermo-mechanical stresses, compactness (typical data of a reactor chamber are: height: 30-60 m, width: 13-40 m, depth: 15-40 m).
The invention provides the following improvements with respect to a Circulating Fluidized Bed Apparatus, hereinafter also called CFBA, fluidized bed apparatus or apparatus and its components, which may be realized individually or in arbitrary combinations as far those combinations are not explicitly excluded hereinafter or excluded by technical reasons. Accordingly individual construction features may be realized individually and/or in arbitrary combinations. Different embodiments may be realized within one apparatus if proper.
Accordingly features, disclosed in connection with one of the following improvements may also be realized in connection with another improvement.
Improvement A refers to a
Fluidized bed apparatus, comprising a circulating fluidized bed reactor with at least one outlet port at its upper part, wherein said outlet port allows a mixture of gas and solid particles exhausted from the circulating fluidized bed reactor to flow into at least one associated separator for separating solid particles from said gas, means to transfer said separated solid particles into at least one fluidized bed heat exchanger and return means to transport at least part of the solid particles back into the circulating fluidized bed reactor, wherein the circulating fluidized bed reactor, the separator and the fluidized bed heat exchanger are mounted in a suspended manner.
The totally suspended (for example hanging) construction allows to adapt the thermal expansions of the associated construction elements and avoids mechanical forces, thermo-mechanical forces and/or moments between adjacent construction parts.
Different thermal loads within the CFBR and an associated FBHR typically lead to different thermal expansions of both construction elements (parts of the apparatus). Accordingly return means (for the solid particles), for example a solid return duct, extending from the FBHR to the CFBR, typically undergoes considerable thermo-mechanical stresses, which now can be avoided.
This is contrary to prior art devices with a suspended reactor, a heat exchanger mounted to ground and a return duct in between.
Optional features are:
Improvement B refers to a:
Fluidized bed apparatus, comprising a circulating fluidized bed reactor with at least one outlet port at its upper part, wherein said outlet port allows a mixture of gas and solid particles exhausted from the fluidized bed reactor to flow into a number (n) of associated separators for separating solid particles from said gas, a number (n) of means to transfer said separated solid particles from said (n) separators into a number (up to n) of discrete fluidized bed heat exchangers, and return means to transport at least part of said solid particles back from said discrete fluidized bed heat exchangers into the circulating fluidized bed reactor, wherein the number (up to n) of discrete fluidized bed heat exchangers are mechanically connected to provide one common fluidized bed heat exchanger with water cooled intermediate walls between adjacent discrete fluidized bed heat exchangers.
Typically each separator is followed by one heat exchanger (with a syphon like seal in between), while the improvement reduces the number of construction parts insofar as at least two, or three, or all (namely n) heat exchangers are combined into one element. This make the apparatus more compact and more effective. Cooling means (water cooled walls) can be designed as common walls between adjacent sections of a combined heat exchanger.
Optional features are:
Improvement C refers to a:
Fluidized bed heat exchanger (FBHE) with a chamber, comprising at least one solid particles inlet port, at least one solid particles outlet port, arranged at a distance to the at least one inlet port, means for introducing a fluidizing gas from a bottom area of said chamber into said chamber, at least one heat transfer means arranged within said chamber, wherein the heat transfer means 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.
The wall like structure (a flat and compact design of an individual heat transfer means) in combination with its orientation are the main features, allowing to arrange a group (set) of multiple heat transfer means at a distance to each other with channels like “cavities/gaps” in between, extending as well in the flow/transport direction of the solid particles towards the outlet area of the chamber.
Insofar the term “wall like” does not refer to a cubic design with flat surfaces but the overall volume which the respective heat transfer means take. A tube, meandering (zig-zag) such that the central longitunal axis of the tube lies in one imaginary plane is an example for a wall-like pattern. Tube sections may extend in different directions along two axis of the coordinate system.
This design allows the solid particles within the fluidized bed to flow between said individual heat transfer means, namely within said spaces (channels) formed between adjacent heat transfer means, without any obstacles (baffles) but including the option to flow from one of said channels/spaces/gaps into an adjacent one.
This is true especially if the discrete heat transfer means are provided be bended tubes/pipes, for example according to one of the following optional features:
Improvement D refers to a:
Fluidized bed heat exchanger with one chamber, comprising at least one solid particles inlet port, at least one solid particles outlet port, arranged at a distance to the at least one inlet port, means for introducing a fluidizing gas from a bottom area of said chamber into said chamber, at least two heat transfer means within said one chamber, each being provided with a heat transfer medium inlet port and a heat transfer medium outlet port, wherein a first heat transfer means is designed as a reheater and second heat transfer means is designed as a superheater to achieve a heat transfer medium pressure above that of the reheater.
This design is best realized with at least two distinct groups/sets of heat transfer means to provide different thermodynamic features within the FBHE and to allow to optimize the heat transfer and efficiency of the FBHE.
All heat transfer means (for example distinct steam tubes) of one group may be linked to one central steam feeding line and steam outlet line respectively. Insofar the extra work for installation is reduced to one further feeding and extracting line, in case of two groups of heat exchangers, while allowing to achieve different thermodynamic conditions within the chamber.
This can be complete by one or more of the following features:
Improvement E refers to a:
Fluidized bed apparatus, comprising a circulating fluidized bed reactor of a vertical axial length L in its functional position, with at least one outlet port at its upper part, wherein said outlet port allows a mixture of gas and solid particles exhausted from the fluidized bed reactor to flow into at least one associated separator for separating solid particles from said gas, means to transfer said separated solid particles into at least one fluidized bed heat exchanger and return means to transport at least part of said the solid particles back into the fluidized bed reactor, wherein the return means are designed such that their lowermost point enters into the fluidized bed reactor at a minimum height of 0.1 L, calculated from the lowermost end of said axial length (L) of the fluidized bed reactor in its functional position.
In other words: This design gives an optimized return position for the solid particles back into the CFBR.
The minimum distance between the bottom area of the CFBR and the place, where the solid particles enter the CFBR, guarantees that the solid particles may freely enter the combustion chamber (the fluidized bed) and avoids any backflow from the fluidized bed, especially from the denseboard (=high pressure zone) of the fluidized bed, being the lowermost section of the fluidized bed, right above the aerated/pressurized bottom. FBHE does not require any complex sealing systems along the return means/outlet port.
The length L of the CFBR is defined as the distance between the upper surface of the aerated bottom (grate-/nozzle area) and the inner surface of the chamber ceiling.
Optional features are:
Yet another improvement (F) relates to a:
Fluidized bed heat exchanger with a chamber, comprising at least one solid particles inlet port, at least one solid particles outlet port, arranged at a distance to the at least one inlet port, means for introducing a fluidizing gas from a bottom area of said chamber into said chamber, at least one heat transfer means, arranged within said chamber, wherein at least one distribution means being arranged in a transition region between said inlet port and said chamber and upstream of said heat transfer means to allow dilution of said solid particles.
This improvement relates to feeding of the particulate material into the fluidized bed heat exchanger (FBHE). The FBHE (its inner chamber/space) typically has a cubic or cylindrical shape of high volume.
If the solid particles, coming from the separator, enter said chamber along a discrete inlet port of limited size, problems may arise in distributing the said particulate material within the chamber and around/between the heat transfer means to achieve the required heat transfer.
The improvement allows to distribute the solid particles on their way into the chamber over a much larger area, depending on the shape and size of the distribution means. At the same time the density of the solids within the particle stream is reduced, which further increases the heat transfer efficiency from the hot particles into the heat transfer medium (a brine, steam or the like).
The term “transition region” includes the end section of the inlet port adjacent to the chamber of the FBHE as well the adjacent section of the chamber and any area in between.
Possible alternatives and embodiments include a fluidized bed heat exchanger with one or more of the following features:
Improvement G refers to a design with a common wall between the CFBR and FBHE, namely a
Fluidized bed apparatus comprising a circulating fluidized bed reactor with at least one outlet port at its upper part, wherein said outlet port allows a mixture of gas and solid particles exhausted from the fluidized bed reactor to flow into at least one associated separator for separating solid particles from said gas, means to transfer said separated solid particles into at least one fluidized bed heat exchanger as well as return means to transport at least part of said solid particles back into the circulating fluidized bed reactor, wherein the said circulating fluidized bed reactor and said fluidized bed heat exchanger have at least one common wall and said return means are provided within said common wall.
This allows to use one wall (section) commonly for 2 independent components of the apparatus and thus to reduce the material and construction costs.
The integration of the return means allows further reductions in construction work, material costs and increases the efficiency. The material flow from the FBHE into the combustion reactor becomes more reliable and more homogeneous.
Optional feature to this improvement include:
A further improvement H relates to a:
Fluidized bed heat exchanger with a chamber, comprising at least one solid particles inlet port, at least one solid particles outlet port, arranged at a distance to the at least one inlet port, means for introducing a fluidizing gas from a bottom area of said chamber into said chamber, at least one heat transfer means, arranged within said chamber, wherein said means for introducing the fluidizing gas are provided by a multiplicity of nozzles arranged along the bottom area of said chamber and different nozzles being charged with different gas pressure.
In other words:
The aerated bottom (the air/gas permeable bottom as part of the fluidized bed) is divided into sections/zones/areas, where air is applied under different pressure. This allows to provide a custom-made pressure profile within the FBHE and thus to optimize the heat transfer and particle transport. A multiplicity of air openings, mostly provided by air nozzles, can be linked to a common air feeding duct or funnel.
Possible embodiments include:
A similar design may be used for a syphon arranged between separator and CFBR according to the following improvement I:
Fluidized bed syphon with a U-shaped chamber, comprising a vertically oriented solid particles entrance port, a vertically oriented solid particles exit port, arranged at a distance to the entrance port, and a horizontally oriented intermediate section in fluidic connection with said entrance port and said exit port, means for introducing a fluidizing gas from a bottom area of said chamber into said chamber, wherein said means for introducing the fluidizing gas are provided by a multiplicity of nozzles, arranged along the bottom area of said chamber and different nozzles being charged with different gas pressure.
The overall design of said syphon, serving as a gas seal between components of the fluidized bed apparatus connected upstream and downstream of said syphon, is similar to that of the fluidized bed heat exchanger as disclosed above. The main difference is, that the syphon does not necessarily comprise any heat transfer means.
To provide a bottom area of the syphon as a fluidized bed and the partition of said fluidized bed into discrete sections allows to adapt the air/gas volume and pressure individually for each of said sections.
One possible arrangement is: A first nozzle set blows air in a counterflow to the solid particles into the entrance port, a second nozzle set provides nozzles which blow air/gas into the mostly horizontally oriented stream of solid particles along the intermediate section while a third nozzle set blows air into the solid particles leaving the syphon via the exit port, wherein air/gas and solid particles have the same transport direction along this exit section.
Optional features for this type of syphon are:
Improvement K relates to a:
Fluidized bed heat exchanger with a chamber, comprising at least one solid particles inlet port, at least one solid particles outlet port, arranged at a distance to the at least one inlet port, means for introducing a fluidizing gas from a bottom area of said chamber into said chamber, at least one heat transfer means, arranged within said chamber, at least one baffle which extends downwardly from a chamber ceiling, substantially perpendicular to a straight line between inlet port and outlet port, with its lower end at a distance to the heat transfer means.
This at least one baffle does not influence the flow of the solid particles within the part of the FBHE equipped with the heat transfer means as it is arranged above said heat transfer means and only serves to redirect the incoming solid particle stream (downwardly) and to equalize the pressure above the fluidized bed and along the horizontal cross section of the chamber, in particular, if provided with opening(s).
The baffles have the function of separation walls and avoid short circuits of the solid material flow (directly from the inlet port to the outlet port). They urge the solid particle stream to penetrate into the heat transfer zone between the heat transfer means (the channels mentioned above). The baffle construction may interact with improvement H.
The following embodiments are optionally included:
The invention is now described with reference to the attached drawing, showing—all in a very schematic way—in
A general concept of a fluidized bed apparatus according to prior art
A cross sectional view of a fluidized bed heat exchanger
A top view on the FBHE 24 of
A cross sectional view of another embodiment of a fluidized bed heat exchanger
A cross sectional view of further embodiment of a fluidized bed heat exchanger A with 2 groups of heat exchangers
A top view on the FBHE of
A top view on a further example for a FBHE 24 with an amended inlet port
A cross sectional view of an FBHE with multiple nozzles sets in the bottom area
A cross sectional view of a syphon with multiple nozzles sets in the bottom area
An general view of a fluidized bed apparatus mounted in a suspended manner
A compact fluidized bed heat exchanger in a 3-dimensional view
In the Figures identical an similar acting construction parts are identified by same numerals.
It comprises:
This concept belongs to prior art. Insofar details are not further illustrated as known to the skilled person.
The invention includes one or more of the following features:
According to
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.
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.
The through holes having the function of discrete outlet ports are shown in
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
Steam is fed into said means 28 via a central feeding line 42, then flowing through the meandering tube (as shown), providing 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.
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
All tubes 28 are connected to the same feeding line 42 and outlet line 44.
The meandering tubes not only give the heat transfer means 28 a wall-like pattern but as well a grid-like structure to allow the particulate material to pass through as well in a horizontal direction.
The horizontally extending sections of said tubes are about three times longer than the vertically extending sections (
As shown in
This allows to avoid any structural means within FBHE 24 which could otherwise urge the solid particles to meander within FBHE. In particular the new design allows to avoid any entrance chamber and/or return chamber for the particulate material to homogenize.
In prior art devices a separate entrance chamber EC with a discrete partition wall is constructed between wall 24w and adjacent part of heat transfer means 28 as well as a separate return chamber RC 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.
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
Fluidization of the particulate material within FBHE 24 is achieved by 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 onto the steam flowing within tube like heat transfer means 28.
The embodiment of
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.
Each of said baffles 50, 52 comprise one opening symbolized by dotted line O to allow pressure adjustment (equalization) within the inner space of FBHE 24.
The said baffle(s) 50, 52 may as well be designed like a curtain, fulfilling the same function as a continuous board, namely to urge the particulate material to flow through said channels C (
In
In the embodiment according to
A first group G1 is made of a number of heat transfer means 28 as shown in
This group G1 of multiple heat transfer tubes 28 connected to a common feeding line 42 and a common outlet line 44 is characterized by a feeding temperature of 480° C. and an outlet temperature of 560° C. of the heat transfer medium (steam) and an average steam pressure of 32 bar, thus fulfilling the function of a so called reheater.
The second group G2 of several heat transfer means 28 is constructed the same way as group G1 but connected so separate inlet lines 42′ and outlet lines 44′ for said steam and designed to achieve a heat transfer medium temperature of between 510° C. (inlet temperature) and 565° C. (outlet temperature) as well as an average 170 bar pressure. This allows to use the tubes of group G2 as a so called superheater.
As shown in
The fluidized bed heat exchanger 24 according to
This distributor means (section 22s) are arranged in a transition region defined by end section of inlet port 22 and the adjacent section of chamber 24, extending upstream of said heat transfer means 28 and extending over about ⅔ of the chamber width.
Ribs 22r protrude from the surface of said distributor 22s and are arranged in a star-like pattern.
Again all walls 14w, 24w and 24s of said FBHE are made of water-cooled tubes with fins between adjacent tubes, symbolized in the right part of
Numerous air nozzles 46 are mounted within bottom 24b. Each nozzle comprises an outer end 46o, protruding downwardly from the outer surface of bottom 24b and an inner end 46i, protruding into the hollow space of FHBE 24 equipped with groups G1, G2 of heat exchange tubes 28.
The nozzles 46 are assembled into five nozzle sets N1, N2, N3, N4 and N5, one behind the other in a row between walls 24w and 14w. All nozzles 46 of a nozzle set are commonly connected to a respective common gas channel 48. If air is fed along one of these channels all corresponding nozzles 46 will be activated to allow air to enter into FBHE 24.
The arrangements of discrete nozzle sets N1 . . . N5 with discrete channels 48 make it possible to set different air pressure in different channels and accordingly to introduce air into the fluidized bed of solid particles within FBHE under different pressure at different areas to optimize homogenisation of the particles within the fluidized bed.
A similar design may be used to improve the syphon-type seal 26 between separator 18 and FBHE 24 or reactor 10 respectively, as illustrated in
A mixture of gas and solid particles like ash coming from separator 18
Similar to the embodiment of
Similar to
While the CFBR 10 and the separator 18 are each directly suspended from base 60b of frame structure 60 (by posts 62), the FBHE 24 is mounted in a suspended manner from separator 18.
Mechanical stability of FBHE 24 is further achieved by said common, water-cooled wall 14w with CFBR 10.
Because of the hanging structure thermal expansion and constriction take place at all components in the same direction and avoids mechanical as well as thermo-mechanical tensions between adjacent construction parts at most.
To make the construction wear resistant, the fluidized bed heat exchanger has no refractory lining; all walls are water cooled metal walls.
The hanging structure allows an integration of a syphon 26 with its return duct 26r without transferring mechanical forces or moments between the respective construction parts.
According to
The lowermost point of return duct 26r of syphon 26 enters the CFBR at a height of the denseboard DB, close to grate 12 and below outlet port 30.
This positioning of the two outlet ports/return means 30,26r to each other is an important combined feature valid for various applications.
In case of an apparatus comprising more than one separator 18, for example 3 separators,
Walls 14i, 14w are made of metal tubes, welded to each other and connected with a fluid source to feed cooling water through said tubes.
Number | Date | Country | Kind |
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13197376 | Dec 2013 | EP | regional |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2014/071693 | 10/9/2014 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
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WO2015/090665 | 6/25/2015 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
4469050 | Korenberg | Sep 1984 | A |
4674560 | Marcellin | Jun 1987 | A |
4716856 | Beisswenger | Jan 1988 | A |
4869207 | Engstrom | Sep 1989 | A |
5014652 | Hyldgaard | May 1991 | A |
5040492 | Dietz | Aug 1991 | A |
5269263 | Garcia-Mallol | Dec 1993 | A |
5316736 | Vidal | May 1994 | A |
5365889 | Tang | Nov 1994 | A |
5634516 | Myohanen | Jun 1997 | A |
5772969 | Hyppanen | Jun 1998 | A |
7562641 | Murakami | Jul 2009 | B2 |
8069824 | Higgins | Dec 2011 | B2 |
Number | Date | Country |
---|---|---|
0332360 | Sep 1989 | EP |
0495296 | Jul 1992 | EP |
9706889 | Feb 1997 | WO |
Entry |
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International Search Report for PCT/EP2014/071693 dated Jan. 23, 2015. |
Number | Date | Country | |
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20170016616 A1 | Jan 2017 | US |