RS55111B1 - FLUIDIZED LAYER DEVICE - Google Patents

Description

DESCRIPTION OF THE INVENTION

[0001] The invention relates to the so-called Circulating Fluidized Bed Apparatus (CFBA) and its components, primarily

Circulating Fluidized Bed Reactor (CFBR) constructed as a combustor, combustion reactor, boiler, gas generator, steam generator, etc., as shown in - or - in US 6,802,890 B2. In a conventional CFBR, gas (air) is passed through a grid-like permeable bottom reactor area, the grid (grid) supporting a fluidized bed of particulate material, the so-called burn-up charge, which generally comprises a fuel-like material such as coal. This contributes to the fact that the fuel and other components inside the fluidized bed behave like a boiling liquid.

[0002] Blown particulate material/fuel mixture allows to improve combustion process and efficiency.

[0003] The combustion charge is fluidized with air/gas, often injected through nozzles. The fluidized layer includes the so-called dense plate area, above the grid and next to the permeable reactor bottom, while the density of material in the form of particles within the fluidized layer becomes smaller within the upper part of the reactor space, which is also called the free area of the fluidized bed.

[0004] The reactor chamber is often confined with outer tubular walls containing water; made of pipes, through which water flows, where said pipes are either welded directly to each other to give a wall structure or with a fin/rib connection between parallel sections of active pipes.

[0005] Like most of the mentioned fuels such as coal, wood, etc., which contain sulfur and/or harmful substances, it is necessary to purify the gases leaving the reactor chamber in a suitable way.

[0006] A CFBR typically has at least one outlet at its upper end, said outlet allowing mixing of gases and solid particles as they exit the reactor to flow into at least one associated separator.

A separator, for example a cyclone separator, serves to separate solid particles (particles, including ash) from said gas. A typical construction of such a separator is shown in US 4,615,715. Again the outer walls of the separator can be constructed

with hollow spaces to allow the passage of water.

Devices for transferring said separated solid particles into at least one Fluidized Bed Heat Exchanger (FBHE) via a suitable inlet opening of said FBHE. These devices can be

passages/pipes/ducts or similar.

Siphon along the path from the separator to the CFBR and/or FBHE to allow separation

of pressure (area) between the separator and the CFBR.

At least one Fluidized Bed Heat Exchanger (FBHE) which allows the use of heat, provided by the particulate material, to generate electricity, for example to heat and increase the pressure of steam carried as a heat transfer medium via pipes or the like, through said FBHE and further to

turbine or similar.

- The FBHE is equipped with at least one outlet, also called return devices, for at least part of the solid particles on their way out of the FBHE and back into the Circulating Fluidized Bed Reactor (CFBR).

[0007] A large number of constructions of such devices and components have been developed during the past decades.

[0008] However, there is still a need for improvements, especially in terms of energy efficiency (typical range of capacity: 50-600MVV - electrical -), efficiency, simple construction, avoidance of mechanical and thermo-mechanical stresses, compactness (typical data of the reactor chamber are: height: 30-60 m, width: 13-40 m, depth: 15-40 m).

[0009] US 7520249 B2 discloses a CFBR comprising a reactor chamber which is divided into combustion sub-chambers and cooling sub-chambers as well as at least one separator, which receives flue gas from the combustion sub-chamber and separates particles from said flue gas. The CFBR further comprises an outer layer, which accepts particles from such a separator, and conducts the particles back to the combustion sub-chamber.

[0010] US 5299532 relates to a CFBR with multiple heat exchangers for solid particles extracted from the combustion chamber, wherein a plurality of heat exchangers communicate with each other through respective openings through which the solid particles can flow to be mixed.

[0011] The aim of the present invention is to improve the functionality of such a CFBR.

[0012] The invention provides the following improvements with respect to Fluidized Bed Circulating Devices, hereinafter also referred to as CFBA, fluidized bed devices or devices and their components.

[0013] The improvement relates to fluidized bed devices according to claim 1.

[0014] A fully suspended (for example when hanging) structure allows to accommodate the thermal expansion of the connected structural elements and to avoid mechanical pressures, thermo-mechanical pressures and/or moments between adjacent structural parts.

[0015] Different thermal loads within the CFBR and the associated FBHE usually lead to different thermal expansions of both structural elements (device parts). Consequently, return devices (for solid particles), for example the solid return channel, extending from the FBHE to the CFBR, are usually subject to significant thermo-mechanical stress, which can now be avoided.

[0016] This is in contrast to prior art devices with a suspended reactor, a heat exchanger placed on the ground and a return channel in between.

[0017] Usually, each separator is accompanied by one heat exchanger (with a siphon like a seal in between), while the improvement reduces the number of structural parts, until now at least two, or three, or all (mostly n) heat exchangers are combined into one element. This makes the device much more compact and more efficient. Cooling devices (water-cooled walls) are constructed as common walls between adjacent parts of a connected heat exchanger.

[0018] Additional features are: Separate fluidized bed heat exchangers are placed in a row (in-line)

in order to provide a common fluidized bed heat exchanger, which

allows a very compact construction.

Water-cooled intermediate walls include water-cooled pipes,

primarily metal pipes.

Water-cooled intermediate walls include water-cooled pipes,

where the adjacent pipes are connected with metal rib connectors. Ribbed

fittings and pipes can be welded.

A common fluidized bed heat exchanger hangs from the separator(s). This is an example of indirect hanging/hanging. The separator can hang from the beam/rod, while the FBHE hangs from the separator. This suspended construction reduces installation costs and

space needed.

A common fluidized bed heat exchanger is fixedly attached to the circulating fluidized bed reactor, giving a compact overall design. Again this is an indirect type of suspension. The FBHE is connected to the CFBR, which

itself can be hung from a suitable frame.

Joint fluidized bed heat exchanger and circulating reactor with

fluidized layer have a common wall. Again this makes the installation compact. The common wall is cooled by water.

The common wall has one or more openings that fulfill the function of return devices (exit opening). Therefore, space for a separate return channel or similar can be

avoided.

A fluidized bed heat exchanger has external chamber walls that are

at least partially cooled by water.

The FBHE is constructed without any structural devices that accelerate the solid particles to swirl inside the fluidized bed heat exchanger. Contrary to conventional designs, the FBHE does not provide any separate inlet chamber and/or return chamber through which the solid particles must pass after entering the FBHE and/or after leaving it. Prior homogenization of solid particles is no longer required. The flow of solid particles enters the FBHE and is currently directed through/along the thermal

exchangers.

The circulating fluidized bed reactor, separator(s) and common fluidized bed heat exchanger are suspended from a support structure, which may be a conventional support structure, for example leg-like or a similar structure

gate, frame, etc.. Mounting of hanging can be realized directly or indirectly. Return devices are constructed as couplings without transmitting mechanical forces or moments from said fluidized bed reactor to said fluidized bed heat exchanger or vice versa. This solution provides in-situ

suspended connection between two structural parts and avoids any mechanical stresses. A fluidized bed heat exchanger does not have a high temperature resistant lining. This makes it lighter, and therefore easier to hang.

[0019] Heat transfer devices can be constructed in a wall-like model that expands substantially parallel to the direction of the main flow of solid particles on their way to and through the outlet.

[0020] The wall-like structure (flat and compact construction of the individual heat transfer devices) combined with its orientation are the main features, allowing to form a group (set) of multiple heat transfer devices at a distance from each other with "cavity/gap"-like channels in between, which expand also in the direction of flow/transport of solid particles towards the outlet area of the chamber.

[0021] To the extent that the term "wall-like" does not refer to a cubic construction with a flat surface, but to the total volume that is respective to the heat transfer devices. A pipe, which curves (zigzags) so that the central longitudinal axes of the pipe lie in an imaginary plane, is an example of a wall-like pattern. Pipe sections can be extended in different directions along the two axes of the coordinate system.

[0022] This construction allows solid particles within the fluidized bed to flow between said individual heat transfer devices, mainly within said space (channel) formed between adjacent heat transfer devices, without any obstacles (partitions) but including the option to flow from one side of the channel/space/gap to the adjacent one.

[0023] This is particularly appropriate if separate heat transfer devices are provided using bent tubes/tubes, for example according to one of the following additional features: The wall-like structure comprises a lattice-like structure. This allows solid particles to flow in all directions of the coordinate system, but holding the barrier

free of the main transport direction towards the exit opening.

The heat transfer device is constructed as a heat exchanger in the form of a pipe for transporting the heat transfer medium and placed in a winding shape, thereby

providing a vertically oriented wall-like structure.

Multiple heat transfer devices are placed at a distance from each other,

forming a set/group of heat transfer devices. This gives a package/set of transfer devices

of heat, which includes more than 50% of the volume of the chamber.

Heat transfer devices cover more than about 60% of the height of the chamber.

Heat transfer devices cover more than about 70% of the height of the chamber.

Heat transfer devices range from slightly above the bottom to slightly below the ceiling of the said chamber. The larger the heat transfer devices, the greater the total exchange

heat more efficient.

The horizontally included parts of the winding heat exchanger tube are at least 3 times longer than the vertically included parts of the heat exchanger tube. This emphasizes

the main direction of transport of solid particles.

Adjacent parts of the same heat exchanger tube are extended at a distance of one in

relative to the other, which is from 0.5 to 2 diameters of the heat exchanger tube.

The walls of the chamber are at least partially cooled by water.

Neither structural device encourages solid particles to meander inside the chamber. Those

FBHE passes in the main direction parallel to the wall of the heat exchanger. The FBHE may share a common wall with an adjacent circulating fluidized bed reactor (CFBR) and the particulate return device may extend at least partially within said common wall to make the installation even more compact.

[0024] According to the solution, the fluidized bed heat exchanger comprises at least two heat transfer devices within one chamber, each provided with an inlet opening for the heat transfer medium and an outlet opening for the heat transfer medium, wherein the first heat transfer device is constructed as a superheater, and the second heat transfer device is constructed as a super heater in order to achieve a pressure of the heat transfer medium that is above that in the superheater.

[0025] This construction is best implemented with at least two different groups/sets of heat transfer devices to provide different thermodynamic characteristics within the FBHE and to allow optimizing the heat transfer and efficiency of the FBHE.

[0026] All heat transfer devices (eg different steam transport pipes) of one group can be connected for one central steam transfer line and steam outlet line respectively. Thus the additional installation work is reduced to one additional transfer line and discharge line, in the case of two groups of heat exchangers, allowing different thermodynamic conditions to be achieved inside the chamber.

[0027] This may be complemented by one or more of the following features: The superheater is designed to allow the temperature of the transfer medium to of heat is up to 600°C (while the inlet temperature of the heat transfer medium, na

example steam, usually around 450 - 550°C).

The superheater is designed to allow the pressure of the heat transfer medium

be up to 50 bar (usually in the range of 30 - 40 bar).

The superheater is designed to allow the temperature of the transfer medium

heat up to 600°C (usually with an inlet temperature between 500 and 580°C). The superheater is designed to allow the pressure of the transfer medium

heat up to 190 bar (usually between 160 and 180 bar).

The fluid pressure in the superheater tubes is usually higher by a factor of 3, or higher by a factor of 4 or even higher by a factor of 5

times than the pressure in the superheater pipes.

The superheater and/or superheater are each made of multiple heat transfer tubes,

each placed to have a sinuous appearance and with a distance from each other. Therefore, the superheater and superheater have a 3-dimensional cube-like profile. Each tube can provide a wall-like (plate-like) structure with a grid-like pattern based on the section of the winding tube. Solid particles pass through the channels between the devices

for heat transfer.

Wall chambers can be at least partially cooled by water.

Again this FBHE and associated CFBR circulating fluidized bed reactor

they can have a common wall to reduce costs and make the device compact. This common wall can be cooled by water.

Any other return devices from separators and/or siphons enter the CFBR slightly above its grid, resp. directly into the dense plate (dense part) of the circulating fluidized bed and below the FBHE return devices.

[0028] Another optional solution includes: At least one heat transfer device placed inside said chamber, wherein at least one distribution device is placed in the transfer area between said inlet opening and said chamber and upstream of said heat transfer device to allow dilution of said solid particles.

[0029] This solution refers to the transfer of particulate material to a fluidized bed heat exchanger (FBHE). The FBHE (its inner chamber/space) is usually cubed or cylindrical in shape with a large volume.

[0030] If solid particles, coming from the separator, enter said chamber along a certain inlet opening of limited size, problems may arise in the distribution of said particulate material within the chamber and around/between the heat transfer devices in order to achieve the required heat transfer.

[0031] This solution allows the distribution of solid particles on their way into the chamber over a much larger surface, depending on the shape and size of the distribution device. At the same time, the density of solid particles within the particle stream is reduced, which further increases the efficiency of heat transfer from the hot particles to the heat transfer medium (salt solution, steam or similar).

[0032] The term "transition area" includes the end portion of the inlet opening that continues to the FBHE chamber as well as the adjacent portion of the chamber and any area in between.

[0033] Possible alternatives and solutions include a fluidized bed heat exchanger with one or more of the following characteristics: Distribution devices are provided with structural elements that protrude from the inner surface of the said inlet and/or chamber. They can protrude from the wall or

the upper (ceiling) part.

Distribution devices are provided with at least one of the following structural elements: rod, button, prism, grid, grid, pyramid, spiral, saw tooth,

piston, blade, nozzle.

Distribution devices comprise >30, >40 or >50% of the length or width of the chamber in order to

homogenized the flow of the fluidized bed inside the chamber to its best appearance. The distribution devices are placed a little upstream from the inlet, or. along

the upper part of the chamber.

The entrance opening enters the chamber from the upper side (ceiling). This gives solid particles

direction of transport followed by gravity.

The inlet enters through the upper part of the chamber wall (). Then the flow of solid particles is considerable

horizontal before entering the chamber.

[0034] In the case of a common wall between CFBR and FBHE, the following solutions can be applied: The specified return devices are provided within the specified common wall. This it allows to use one wall (section/part) that is common to 2 independent components of the device and therefore reduces material and construction costs.

The integration of return devices allows further reduction in construction work,

material costs and increased efficiency. Material flowing from the FBHE to the reactor

combustion becomes safer and more homogeneous.

Return devices are supplied with at least one free opening in the assembly

of the said common wall, this is very simply and efficiently constructed. Return devices are multiple free holes placed at a certain distance of one

from the other (for example in a horizontal line) within the mentioned common wall. At least one free hole is inclined, with the lower end leading to the fluidized bed heat exchanger and the higher end leading to the fluidized bed reactor. This reduces the risk of particle infiltration from the fluidized medium

of the CFBR layer in FBHE.

The common wall forms a three-dimensional profile directed towards the fluidized bed heat exchanger. This allows to partially or completely integrate

beveled outlet to the common wall area.

The common wall forms a bulge towards the fluidized bed heat exchanger. Again this allows the inclined exit channel/port to be integrated into the split wall and keeps the pressure of said exit material low.

[0035] Said devices for introducing fluidized gas can be provided with a large number of nozzles placed along the bottom of said chamber and different nozzles filled with different gas pressures.

[0036] In other words: Aired bed (permeable bed for air/gas as part of fluidized bed) is divided into parts/zones/areas, where air is applied under different pressure. This allows to provide a tailor-made pressure profile within the FBHE and therefore to optimize heat transfer and particle transfer. A large number of air openings, generally provided with air nozzles, can be connected for a common air distribution channel or funnel.

[0037] Possible solutions include: A large number of nozzles are divided into two or more nozzle sets; each set of nozzles comprises a number of nozzles, where each set of nozzles can be filled with an individual gas under pressure, for example with a different gas pressure. The nozzles of a set of nozzles are placed within a common area. This allows the entire lower area to be divided into two, three or more large sections.

The gas pressure of the nozzle set is adjustable. This allows the gas pressure to be adjusted

according to local requirements.

Each set of nozzles is connected to a corresponding gas channel or space for gas distribution respectively in order to set the required pressure appropriately in

with respect to all nozzles of the lubricator set connected in this way.

A fluidized bed heat exchanger without any structural devices (except the inlet distribution device and the heat transfer device) allows the solid particles to pass through the chamber without further winding, on the contrary: their path through the FBHE is mainly influenced by the air pressure along the bottom grid.

[0038] At least one partition may extend downward from the ceiling of the FBHE chamber, substantially normal to a straight line between the inlet port and the outlet port, with its lower end at a distance from the heat transfer device.

[0039] This at least one baffle does not affect the flow of solid particles within the part of the FBHE equipped with heat transfer devices as placed above said heat transfer device and only serves to divert the incoming flow of solid particles (downward) and to equalize the pressure above the fluidized bed and along the horizontal section of the chamber, preferably, if equipped with opening(s).

[0040] Partitions have the function of separation walls and avoid short circulation of the flow of solid material (directly from the inlet opening to the outlet opening). They encourage the flow of solid particles to penetrate the heat transfer zone between the heat transfer devices (channels previously mentioned).

[0041] The following solutions are optionally included: At least one partition extends between opposite walls of the chamber to improve

described effect.

At least one partition has at least one opening to allow

pressure adjustment/compensation inside the chamber.

At least one compartment is at least partially cooled by water.

At least one partition is constructed as a curtain. The curtain defines a partition with a large number of small openings that allow equalization of pressure, but avoids penetration

solid particles to a large extent.

A large number of baffles are placed at a distance from each other along said line between the inlet opening and the outlet opening.

The heat transfer devices are also constructed as a tubular heat exchanger for the transfer of the heat transfer medium and arranged in a tortuous manner, thereby providing a vertically oriented wall-like model. Individual heat transfer walls extend perpendicular to the partitions.

[0042] The description is now described with reference numerals shown in the drawings, showing

- all in a very schematic way - on

Picture 1

General concept of a fluidized bed device according to the state of the art

Picture 2

Cross section of a fluidized bed heat exchanger

Picture 3

Top view of FBHE 24 Figures 2 along line 3-3

Figure 4

Cross-section of another fluidized bed heat exchanger solution

Figure 5

Cross section of the second fluidized bed heat exchanger solution A with 2 groups of heat exchangers

Figure 6

Top view of FBHE Figures 5 along line 6-6

Figure 7

Top view of another example for the FBHE 24 with modified inlet opening

Figure 8

Cross-section of an FBHE with a multiple set of nozzles in the lower region

Figure 9

General view of a fluidized bed device mounted in a manner that applies suspension

Figure 10

Compact fluidized bed heat exchanger in 3-dimensional view

[0043] In the Figures, identical and similar structural parts are shown with the same reference numbers.

[0044] Figure 1 shows the general concept of a fluidized bed device and its main components according to the present invention.

[0045] It contains: Circulating Fluidized Bed Reactor (CFBR) 10. Its lower part includes a lattice-like structure 12 through which air (arrow A1) was blown into the reactor chamber 14 via (not shown) nozzles, thus providing a fluidized bed (dense plate - DB -) above said lattice 12, wherein said dense plate

contains particulate matter such as coal, wood, etc. which will be set on fire.

The CFBR has two outlet openings 16 on opposite sides of its upper part,

allowing mixing of gas and solids discharged from the CFBR to flow into associated separators 18, generally a cyclone separator. Separators serve to separate worms

particles from the gas.

The transfer devices 20, constructed as channels (passage), extend from the lower end of each separator 18 downward and towards the outlet opening 22 along the ceiling 24c of the thermal

fluidized bed heat exchanger (FBHE) 24.

A siphon-like construction tube 26 (U-shaped) extends from the lower end of each separator 18 toward the reactor chamber 14 and enters the chamber 14 just above the grate 12

the aforementioned CFBR.

The FBHE is equipped with (plate-like) heat transfer devices 28 and an outlet 30 connecting the reactor chamber 14 at the same vertical height as the pipe structure 26 .

[0046] This concept belongs to the state of the art. To that extent, the details are not further illustrated because they are known to the skilled person.

[0047] According to Figure 2, the fluidized bed heat exchanger 24 shows an inlet opening 22 at its upper end (in Figure 2: upper left) and an outlet opening 30 at its upper end (in Figure 2: upper right), resp. opposite to each other. Said outlet 30 provides return devices for solid particles transported along the transfer channel 20 into said FBHE and is provided within the common wall 14w of chamber 14 and FBHE 24.

[0048] The exit opening 30 comprises multiple through openings, placed in a horizontal line with a distance from each other along the corresponding part of the wall of said wall 14w.

[0049] Said wall 14w is water-cooled, generally constructed of vertically placed tubes with ribbed connectors placed between adjacent tubes. The pipes are cooled by water passing through said pipes.

[0050] Through holes that function as separate exit holes are shown in Figure 2 in a slightly slanted orientation, with the lower end toward the fluidized bed heat exchanger 24 and the upper end toward the fluidized bed reactor chamber 14 .

[0051] This oblique orientation (slanted outlet 30) can be placed as part of a 3-dimensional profile (for example as a projection 14w') of said wall 14w towards the inner space/chamber of the fluidized bed heat exchanger 24 as shown by broken lines in Figure 2 and designated by the number 30'.

[0052] Figure 2 further shows the shape and construction of the heat transfer device 28 within the fluidized bed heat exchanger 24. The picture shows only one of the mentioned heat transfer devices. Further heat transfer devices of the same construction are placed at a distance from each other within FBHE 24 (perpendicular to the projection plane).

[0053] Steam is introduced into said devices 28 via a central transfer line 42, then flows through a tortuous pipe (as shown), which is mounted on said device 28, and exits via a common outlet line 44, allowing heat to be taken from the particulate material (indicated by dots P) moving through the FBHE 24 between inlet port 22 and outlet port 30.

[0054] It is very important that each said device 28 is constructed according to a wall-like model and continues substantially parallel to the main flow path of the solid particles on their way to and through the outlet opening 30, indicated in Figure 2 by arrow S.

[0055] All pipes 28 are connected to the same transmission line 42 and output line 44.

[0056] The curved tubes not only give the heat transfer devices 28 a wall-like pattern but also a grid-like structure to allow particulate material to pass through the wall in a horizontal direction.

[0057] The horizontal covered areas of said tubes are about three times longer than the vertical covered areas (Figure 2 is not taken into consideration). The boundary horizontal regions are spaced at a distance from each other that is approximately the size of the pipe diameter.

[0058] As shown in Figure 2, the heat transfer devices 28 cover no more than 60% of the chamber height, which is the distance between the chamber bottom 24b and the chamber ceiling 24c. In the solution of each mentioned wall-like heat transfer device 28 extends from slightly above the bottom 24b to slightly below the outlet opening 22 and slightly outside the wall 14w to slightly outside the opposite wall 24w.

[0059] This allows avoiding any structural devices within the FBHE 24 that might otherwise accelerate solid particles to meander within the FBHE. Primarily, the new construction allows to avoid any inlet chamber and/or return chamber for particulate material to be homogenized.

[0060] In the prior art device, a separate inlet chamber EC with a separate wall partition is constructed between the wall 24 w and the adjacent part of the heat transfer device 28 as well as a separate return chamber RC between the wall 14 w and the parts 28. These walls and chambers cause the flow of solid particles to flow down and up, which is now avoided with the new construction without any partition walls.

[0061] The particulate material can move in the direction from the inlet opening 22 to the outlet opening 30 (see arrow S) along the channel/slot C formed between adjacent tubes (heat transfer devices), as can be seen in Figure 3.

[0062] Fluidization of the particulate material within the FBHE 24 is achieved with air nozzles 46 in the lower region 24b. The particulate material is circulated with said cleaning agents within the FBHE 24 in order to optimize heat transfer from the solid particles P to the steam flowing within a pipe such as device 28 .

[0063] The solution of Figure 4 differs from Figure 2, 3 in that the two partitions 50, 52 continue from the ceiling 24c downwards, ending slightly above the heat transfer device 28. These partitions 50, 52 continue substantially perpendicular to the straight line between the inlet opening 22 and the outlet opening 30 (dashed line L).

[0064] Both partitions 50, 52 which are placed between the opposite walls of the FBHE 24 (only one, mainly 24s is shown), represent the walls connecting said walls 14w, 24w. Partitions 50, 52 are placed at a distance from each other.

[0065] Each of said partitions 50, 52 comprises an opening marked with a broken line O to allow pressure adjustment (equalization) within the internal space of the FBHE 24.

[0066] Said partition(s) 50, 52 may also be constructed as a curtain, fulfilling the same function as a continuous plate, mainly to accelerate the flow of particulate material through said channels C (Figure 3) between adjacent heat transfer devices 28 on their way between inlet opening 22 and outlet opening 30.

[0067] In Figure 4, the outlet opening 30 is extended, generally protruding into the circulating fluidized bed reactor 10.

[0068] In the solution according to Figure 5, a large number of heat transfer devices 28 are divided into two groups.

[0069] The first group G1 is made of a number of heat transfer devices 28 as shown in Figures 2, 3 with the exception that the horizontal extension between walls 24w, 14w is much shorter and ends about halfway between said walls 14w, 24w.

[0070] This group G1 of a greater number of heat transfer tubes 28 connected for a common transmission line 42 and a common outlet line 44 is characterized by a transfer 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, fulfilling the function of a so-called superheater.

[0071] Another group G2 of several heat transfer devices 28 is constructed in the same way as group G1 but connected to separate inlet lines 42' and outlet lines 44' for said steam and designed to achieve a temperature of the heat transfer medium between 510°C (inlet temperature) and 565°C (outlet temperature) and an average pressure of 170 bar. This allows the use of group G2 tubes as a so-called super heater.

[0072] As shown in Figure 5, the pipes of the group G2 are placed near the outlet 30 and next to the wall 14w, while the pipes of the group G1 are placed next to the wall 24w with a distance between the groups G1 and G2.

[0073] Figure 6 shows a top view of Figure 5 along line 6-6 of Figure 5.

[0074] Fluidized bed heat exchanger 24 according to SI. 7 shows a different construction around the inlet opening 22, which expands towards the inner space of the chamber 24, wherein said widened part 22w is further inclined towards the lower area 24b of the FBHE 24 to provide a distribution device that allows the entry of the stream of solid particles to expand, essentially to fill the entire width of said inner space of the chamber 24, the width being defined by the distance of said wall 24s.

[0075] This distribution device (part 22s) is placed in the transfer region defined by the end part of the inlet opening 22 and the adjacent part of the chamber 24, which extends upstream of said heat transfer device 28 and extends over about 2/3 of the width of the chamber.

[0076] Ribs 22r emerge from the surface of said distributor 22s and are arranged according to a star-like pattern.

[0077] Again, all walls 14w, 24w and 24s of the above FBHE are made of water-cooled tubes with finned joints between adjacent tubes, marked in the right part of Figure 7.

[0078] Figure 8 shows the FBHE 24 characterized with a modified bottom 24b.

[0079] A large number of air nozzles 46 are mounted inside the bottom 24b. Each nozzle includes an outer end 46o projecting downwardly from the outer surface of the bottom 24b and an inner end 46i projecting into the cavity of the FHBE 24 equipped with groups G1, G2 of heat exchanger tubes 28.

[0080] The nozzles 46 are composed of five nozzle sets N1, N2, N3, N4 and N5, one behind the other in a row, between the walls 24w and 14w. All of the nozzles 46 of the nozzle set are typically connected to a corresponding common gas channel 48. If air passes along one of these channels, all of the corresponding nozzles 46 will be activated to allow air to enter the FBHE 24.

[0081] The arrangement of separate sets of nozzles N1 ...N5 with separate channels 48 makes it possible to set different air pressures in different channels and therefore to inject air into the fluidized bed of solid particles within the FBHE at different pressures in different areas in order to optimize the homogenization of particles within the fluidized bed.

[0082] A similar construction can be used to improve the seal 26 in the form of a siphon between the separator 18 and the FBHE 24 or the reactor 10 respectively.

[0083] A mixture of gas and solid particles such as ash exits the separator 18

they enter the inner pipe of the siphon 26 in the shape of the letter U in the downward direction,

then it is fluidized with a construction in the form of a fluidized layer in the lower area

26b said inner tubes through nozzles 27,

turns about 90 degrees,

flows along the intermediate chamber part 26i, where fluidization continues, then passes into the outer tube of the U-shaped siphon 26, where fluidization continues through

nozzles 27 on the lower part of said outer tube, before

flows along the second part of the U-shaped pipe and enters the CFBR 10 through the corresponding return

lines.

[0084] Similar to the solution of Figure 8, the plurality of air nozzles 27 is divided into three sets of nozzles SN1, SN2 and SN3, each with a certain number of nozzles 27, and each connected to the corresponding air channel D1, D2 and D3, conveying air to the corresponding nozzles 27 under the same or different pressure.

[0085] Similar to Figure 8, the air ducts D1..D3 have a funnel shape at their upper ends.

[0086] Figure 9 represents fluidized bed devices where its main components, mainly the CFBR 10, the FBHE 24 as well as the corresponding separators 18 are connected to a central supporting structure by means of suspension, mainly the frame 60. The frame 60 has the shape of an inverted U with its legs 601 fixed inside the substrate GR.

[0087] While the CFBR 10 and the separator 18 are each directly attached to the base 60b of the structure in the form of a frame 60 (places 62), the FBHE 24 is connected in the form of attachment to the separator 18.

[0088] The mechanical stability of the FBHE 24 is further achieved by said common, water-cooled CFBR 10 wall 14w.

[0089] Due to the suspended structure, thermal expansion and contraction takes place in all components in the same direction and mostly avoids mechanical as well as thermomechanical stresses between adjacent structural parts.

[0090] In order to make the construction resistant to wear, the fluidized bed heat exchanger does not have a lining resistant to high temperature; all walls are water-cooled metal walls.

[0091] The hanging structure allows the integration of the siphon 26 with its return channel 26r without the transmission of mechanical forces or moments between the corresponding structural parts.

[0092] According to Figure 9, the lowest possible point LP1 of the outlet opening 30 of the fluidized bed heat exchanger 24 enters the fluidized bed circulating reactor 10 at a height that is >0.15L, calculated from the lowest end of the axial length L of the CFBR 10. The lowest end is defined by the grid 12 of the fluidized bed. A minimum distance of >0.1L, better than >0.2L, allows to place the return devices 30 outside the so-called dense plate DB and avoid the risk of any backflow of solid particles from the fluidized bed inside the reactor 10 into the associated structural elements such as the FBHE 24. This feature can be combined with inclined outlets 30 as described in Fig. 2 or inclined return channels 26r.

[0093] The lowest point of the return channel 26r of the siphon 26 enters the CFBR at the height of the dense plate DB, close to the grid 12 and below the outlet opening 30.

[0094] This positioning of the two outlet/return devices 30,26r relative to each other is a very important combined feature valid for various applications.

[0095] In the case of devices consisting of more than one separator 18, for example 3 separators, Figure 10 shows a solution with three respective fluidized bed heat exchangers 24.1, 24.2, 24.3 mechanically connected to provide one common fluidized bed heat exchanger 24 of a suitable, suitable size, with central walls 24i. Again: all three wall partitions 14w of the same heat exchanger 24 are part of the reactor wall 14, resp. water-cooled common wall with integrated outlet openings 30.

[0096] The walls 14i, 14w are made of metal tubes, welded to each other and connected to a fluid source to flow cooling water through said tubes.

Claims (9)

1. Fluidized bed devices, comprising a circulating fluidized bed reactor (10) with at least one outlet opening (16) on its upper part, wherein said outlet opening (16) allows the storage of gas and solid particles exiting the fluidized bed reactor (10) to flow into a plurality (n) of connected separators (18) for separating solid particles from said gas, a plurality (n) of devices (20) for transferring said separated solid particles from said (n) separators (18) into a number (up to n) of isolated fluidized bed heat exchangers (24.1, 24.2, 24.3), and return devices to transfer at least a portion of said solid particles back from said isolated fluidized bed heat exchangers (24) to a circulating fluidized bed reactor (10), wherein each insulated fluidized bed heat exchanger contains chamber, containing at least one solid particle inlet, at least one solid particle outlet, spaced from at least one inlet, devices for injecting fluidized gas from the bottom of said chamber into said chamber, a plurality of heat transfer devices placed within said chamber, wherein the individual heat transfer device is constructed in a wall-like structure and the set of multiple heat transfer devices are spaced apart with channels in between, wherein the heat transfer devices and channels continue substantially parallel to the main flow of solid particles in their path as well as through the exit opening, a number (up to n) of separated fluidized bed heat exchangers (24.1. 24.2, 24.3) are mechanically connected to provide one common fluidized bed heat exchanger (24) with an intermediate wall (24i) that is cooled by water between adjacent separated heat exchangers (24.1, 24.2, 24.3) with a fluidized bed, the circulating fluidized bed reactor (10), said (n) separator(s) (18) and the common fluidized bed heat exchanger (24) are arranged to hang. 2. Fluidized bed devices according to claim 1, wherein the separate fluidized bed heat exchangers (24.1, 24.2, 24.3) are placed in line to provide a common fluidized bed heat exchanger (24). 3. Fluidized bed devices according to claim 1, wherein the water-cooled intermediate walls (24i) contain water-cooled pipes. 4. Fluidized bed devices according to claim 1, wherein the water-cooled interstitial walls (24i) comprise water-cooled tubes, where adjacent tubes are connected by metal rib connectors. 5. Fluidized bed devices according to claim 1, wherein the common fluidized bed heat exchanger (24) is suspended from the separator(s) (18). 6. Fluidized bed devices according to claim 1, wherein the common fluidized bed heat exchanger (24) and the circulating fluidized bed reactor (10) have a common wall (14w). 7. Fluidized bed devices according to claim 6, wherein the common wall (14w) is cooled by water. 8. Fluidized bed devices according to claim 6, wherein the common wall (14w) has one or more openings (30) that fulfill the function of return devices. 9. Fluidized bed devices according to claim 1, wherein the common heat exchanger (24) has chamber walls (14w) that are at least partially cooled by water.