WO1998038121A1

WO1998038121A1 - Assembly for providing a laminar gas flow for fluidization or transport of bulk solids

Info

Publication number: WO1998038121A1
Application number: PCT/FI1998/000148
Authority: WO
Inventors: Jukka Hirvenoja; Erkki Parvio
Original assignee: Imatran Voima Oy; Fortum Power and Heat Oy
Current assignee: Imatran Voima Oy; Fortum Power and Heat Oy
Priority date: 1997-02-26
Filing date: 1998-02-18
Publication date: 1998-09-03
Anticipated expiration: 1999-08-26
Also published as: FI104247B; CN1248955A; RO119143B1; HUP0002180A2; FI104247B1; AU6216698A; FI970815A0; FI970815A7; PL335327A1; EP1053194A1; HUP0002180A3

Abstract

The present invention relates to an assembly for providing a laminar gas flow serving, e.g., to form a fluidized mixture of solids with a gas, said assembly comprising a plenum chamber (3) forming a closed space containing a gas infeed pipe (5) for blowing gas into the plenum chamber and a feeder pipe (1) into which said laminar flow is to be formed and whose one end (2) is adapted into said plenum chamber. The lower end (2) of said feeder tube (1) adapted into said plenum chamber (3) is formed into a diffuser mouth (8) of rotationally symmetrical shape having its inner diameter flared in a horn-like manner so that the inner diameter of the tube end is expanded smoothly toward the rim of its diffuser mouth facing the bottom of said plenum chamber (3), and the bottom (10) of said plenum chamber (3) at the area facing said mouth (8) is adapted at a constant distance from the rim of said mouth (8) over the area facing the perimeter of the mouth.

Description

Assembly for providing a laminar gas flow for fluidiza- tion or transport of bulk solids

The invention relates to an assembly according to the preamble of claim 1 for providing a laminar gas flow serving, e.g., to form a fluidized mixture of solids with a gas. The invention makes it possible to implement a feed apparatus for fluidized solids, suitable for transporting solid fuels and the like by means of a carrier gas flow.

Generally, particular attention is paid to create a laminar pattern of a gas infeed flow in the transport of particulate matter and different fluidized-bed systems. Typically, a laminar flow of gas is assured by making a grate either from a perforated plate, or alternatively, by employing a plurality of nozzles with a required number of small orifice openings, whereby the nozzles are mounted on gas distribution base plate. Such arrangements are conventionally used in fluidized-bed boilers and FBC cracking reactors of oil refineries. Occasionally, laminar flow can be maintained in a vertical tube such as those used in pneumatic conveyors and flash dryers by virtue of a sufficiently long stabilizing passage of the flow, whereby the system may be complemented with a venturi that is placed close to the infeed point of the particulate matter, generally below the infeed point.

The use of a venturi or perforated plate is a safe choice of gas flow design provided that the pressure drop over the venturi restriction can be kept sufficient high. However, pneumatic systems typically also require a large volume rate of the gas flow, whereby a centrifugal fan in the generation of such a flow is an economical device in most aspects, but has a poor static pressure capability. Consequently, devices must be designed capable of distributing the carrier gas into the flow uniformly at a minimized head loss, wherein exact calculations are required and no major variations in gas flow velocity are allowed. All such air distribution arrangements may be collectively- categorized as grates.

The second essential function required from a grate is a capability of suspending the solids above it even if the gas flow would be interrupted for some reason. Hence, perforated plates do not generally appear to offer a practicable solution. While perforated plates can be made to fulfill said requirement, the diameter of the plate openings should be smaller than about twice the mean diameter of the solids particles, whereby the particles are prevented from passing through the openings. In many cases this leads to an impracticably small and easily plugging grate, thereby excluding the use of the perforated plate type of grate.

In pneumatic conveyors and fluidized-bed constructions, a problem frequently arises from the accumulation of coarse aggregate material into the interior of the apparatus necessitating the discharge of the disturbing material from the process. In devices equipped with a horizontal perforated plate or a plurality of gas distribution nozzles mounted on a horizontal base plate, the system is generally provided with discharge openings for the removal of such aggregate fraction of solids. These kinds of grates are firstly problematic due to the large horizontal surface of the grate over which the heavy aggre- gate solids are not easily transported toward the discharge openings and, secondly, due the nozzles on which the aggregate solids tend to adhere. An approach to alleviate these problems has been sought from an increased removal rate of the aggregate material, which leads to a secondary problem of increased loss of useable material. In pneumatic conveyors or other systems having the flow laminarized by means of a venturi, the discharge of aggregate material can be arranged to occur via the throat of the venturi, or alternatively, if the venturi is not used, the aggregate material is still easier to manage by allowing it to drop to the bottom of the tube. Thence, it is relatively simple to perform the removal of coarse aggregate material from the tube bottom. However, a problem may arise herein from the large height required by the system. If the gas infeed is arranged in a conventional manner via a T-joint, whereby the flow first takes place along a horizontal tube into a vertical tube or channel, a free flow length of about 3 times the tube diameter must be provided from the lower edge of the horizontal tube section vertically upward before the particulate matter is introduced into the gas flow. This flow-stabilizing length of the flow channel can readily reach a height as large as several meters and, thus, sometimes make the design unrealizable due to the substantial need for installation space.

Pneumatic conveyors are discussed in, e.g., patent publications GB 2,140,377 and WO 85/01930.

Feed equipment for solid fuels are employed, e.g., in the infeed of solid fuels into dryers, boilers and similar units. In fluidized-bed boilers and dryers, such equipment is used in the feed of the circulating fluidized-bed material. Herein, the fluidizing gas is typically passed, e.g., in fluidized-bed dryers via gas distribution nozzles having a number of small-diameter orifice openings. Simultaneously, the fluidizing medium and the fuel are injected from aside into the fluidized-bed zone formed above the nozzles. By virtue of a sufficiently dense placement of the nozzles, the gas flow pattern can be made satisfactorily uniform which does not, however, prevent the infeed flow of fuel and the fluidizing medium from causing natural variations of material density and flow disturbances in the bed. An alternative method of material infeed is to use a venturi, whereby the solids are fed into a dryer for instance via a venturi infeed tube connected to the lower section of the dryer. However, the -length of such a infeed tube placed under the dryer will become substantial, because of the space occupied by the venturi itself and since the gas flow must be allowed to become laminar prior to its entry into the venturi restriction and also kept laminar at its exit from the restriction in order to assure a nonturbulent flow. Alternatively, the carrier gas can be injected into the feed channel via nozzles mounted on the wall of the channel or via nozzles provided at the ingoing end of the feed channel, in its conical section. Such gas inlet nozzles are particularly employed in arrangements having the lower section of the feed channel equipped with a valve for the removal of large-diameter solids such as rocks or similar impurities. Obviously, this design cannot have gas distribution nozzles or a gas inlet nozzle at the valve location. Conventionally, the gas is passed to the gas inlet nozzle or distribution nozzles via a plenum chamber surrounding the lower end of the infeed section, whereby the plenum chamber serves to distribute the injected gas uniformly.

The greatest handicap of pneumatic feeders is their large need of installation space in the vertical direction. As a long section of the flow channel must be provided both in front and after the solids infeed point in order to achieve stabilization of the gas flow, the length of flow channel/tube must often be made vertically as long as several meters. The gas velocity must stay relatively constant in the channel/tube, because when the flow velocity is essentially higher in the center of the channel/tube with regard to the velocity near its inner wall, the material flow in the vicinity of the wall may become reverse, thus causing feed disturbances and even plugging or pressure pulsations due to the accumulation of the material being fed. Obviously, the vertically elongated structure increases the cost of the construction. High-rise dryers and similar equipment also require large free height at the installation site, or alterna- tively, the equipment must be arranged to pass through the intermediate floor structures of the building, whereby the equipment occupies space in several storeys . Such constructions make layout design difficult and increase the costs of equipment manufacture. High structures need a variety of support structures and their servicing is clumsy. Also the gas injector nozzles of pneumatic feeders are readily plugged thus requiring periodic maintenance during which the equipment is unavailable.

It is an object of the present invention to provide a short assembly capable of forming a laminar gas flow in a feeder tube or similar channel. It is a further object of the invention to achieve a solids feeder apparatus with a lower height than those of prior-art constructions by virtue of providing a gas flow of relatively constant velocity profile in the feeder channel.

The goal of the invention is achieved by adapting a feeder tube into a plenum chamber, advantageously close to the bottom of the plenum chamber, with the ingoing end of the feeder tube made into a rotationally symmetrical infeed tube with a horn-like flared rim so that the inner diameter of the tube end is made smoothly expanding toward the rim of its diffuser mouth facing the bottom of the plenum chamber.

More specifically, the assembly according to the invention is characterized by what is stated in the characterizing part of claim 1.

The invention offers significant benefits, The invention makes it possible to achieve laminarization of the gas flow over a very short length of the feeder tube, whereby the infeed point of the carrier gas need not be outdistanced far from the solids infeed point of the feeder tube. Hence, the equipment situated above the solids infeed point can be placed at an essentially lower height than in prior-art equipment, which simplifies the layout planning of, e.g., dryers in boiler plants. As compared with the height of conventional feed equipment, the arrangement according to invention results in a feeder with a height several meters shorter than that of conventional feeder constructions. As opposed to the above-described prior-art constructions, the gas velocity in the feeder channel, in vicinity of the channel entrance end, is highest close to the channel wall. This is due to acceleration of the flow at the edge of the flared entrance opening of the channel. However, the velocity differential herein is small and disappears over a short distance. The faster flow in the vicinity of the channel wall gives the benefit that no slow-moving boundary layer will be formed close to the wall in which layer the material being fed could fall downward. Result- ingly, the portion of particulates escaping entrainment with the carrier gas flow is reduced.

A single, large-diameter gas infeed pipe will not become plugged as readily as small-diameter openings, and the gap between the feeder channel entrance opening and the bottom of the plenum chamber is anyhow easily cleaned. Hence, the need for servicing is reduced and the operating reliability is improved. Heavier or larger-diameter solids, which may enter along with the flow of material being fed and then fall downward with the gas flow, can be removed via the large-diameter gas infeed opening. At the gas infeed opening, directly thereunder, can be arranged a group of series-connected gate valves on which the aggregate impurities accumulate and via which the aggregate material can be removed simply by opening the gate valves in a succession. Such operation of the lock gates and accumulation of impurities thereon do not cause any disturbance to the function of the feeder equipment. In equipment designed according to the invention, the velocities of the carrier gas and the material being conveyed, as well as the pressure drop in the feeder section, remain small. Consequently, conventional compressors and high-pressure pumps can be replaced by fans as prime movers of the carrier gas flow.

Besides for conveying materials, the invention may be employed for laminar flow transport of gas to a desired point. In such an application, the assembly according to the invention can replace a gas distribution nozzle field comprised by a plurality of small injectors nozzles, whereby the implementation of the structure becomes more cost-effective.

The invention is suitable for the transport and feed of all such materials that cannot be conveyed fluidized in a carrier gas flow. The embodiment is realized without any type of ejector flow, simply by passing the entire gas flow directly from a fan into the feeder channel.

In the following, the invention is described in greater detail by making reference to the appended drawings in which

Figure 1 is a schematic diagram of a feeder construction according to the invention;

Figure 2 is a schematic diagram of an embodiment of the invention; and

Figure 3 is a schematic diagram of a second embodiment of the invention. Referring to the diagrams, the uniform distribution according to the invention of a gas flow is implemented by virtue of a plenum chamber 3 that forms a closed space and a suitably shaped lower end 2 of the feeder tube 1. The lower end 2 of the feeder tube is formed into a rota- tionally symmetrical, flared mouth 8, which is surrounded by the plenum chamber. The radius of curvature of the mouth 8 may be selected relatively freely, provided that the cross-sectional diameter of the mouth is made to flare smoothly so as to form a horn-like section at the lower end 2 of the feed tube. The internal surface of the mouth 8 must be made smoothly curved, flaring toward the bottom of the plenum chamber in order to assure that the gas flow follows the internal surface of the tube mouth 8. The lower end 2 of the feeder tube and the mouth 8 thereof is surrounded by a plenum chamber 3 , whose bottom 10 is adapted in the vicinity of the rim 11 of the mouth 8. The distance between the mouth rim 11 and the plenum chamber bottom 10 determines the gas velocity in this gap and thus serves to assure uniform distribution of the gas flow entering the feeder tube 1 from the plenum chamber 3 into which the gas is introduced via the gas infeed pipe 5. While the distance between the mouth rim 11 and the plenum chamber wall may obviously have different design values, it is essential that the mouth rim-to-chamber bottom gap is equally wide over the entire rim of the mouth 8. At the rim of the mouth 8, the bottom of the plenum chamber 3 can be provided with a gate opening, but then the flat area of the bottom must cover an area which surrounds the opening so as to extend from an area remote to the maximum diameter of the mouth 8 radially inward to at least the point facing the internal edge of the mouth rim 11 in order to form the above-described gap serving to distribute the gas in a smooth laminar flow in cooper- ation with the shape of the mouth 8 into the feeder tube 1. The feeder tube 1 rises upward from the plenum chamber 3 with a slightly conically expanding cross section. -Immediately above the plenum chamber 3 is adapted a solids infeed nozzle 4, such as the fluidized material infeed nozzle of a flash dryer, for instance. As known in the art, the term flash dryer refers to a dryer type based on blowing the material to be dried upward in a long tube or channel, whereby drying takes place rapidly during the short residence time of the material in the channel under the effect of the heat introduced therein. The solids can be fed into the infeed nozzle 4 by means of feeder device, or alternatively, the material may flow under gravity therein from a container or collector system located higher above. However, the solids flow velocity must be kept sufficiently low to prevent the solids from reaching the opposite wall of the feeder tube 1, but rather entering as a spray to mix the solids freely with the carrier gas flow rising from below. This type of feeder is particularly well suited for the feed of fluidized bed material of a flash dryer, whereby the feeder tube 1 is connected to the dryer and the solids infeed nozzle to some section of the circulating sand circuit of a fluidized-bed boiler, e.g., to the return circuit nozzle of the cyclone or the fluidized-bed zone of the boiler. In such a connection, the energy used in the drying process, or at least a portion thereof, is introduced into the dryer as the heat content of the circulating fluidized solids. The carrier gas may be steam, air or circulating gas, and thus, at least a portion of the drying energy can be introduced into the dryer as the heat of the carrier gas used for transporting the material being dried.

Under the opening located below the feeder tube mouth, the plenum chamber bottom 10 is provided with an impurities discharge pipe 9 , which is closed by a gate valve 6. While the inner diameter of the discharge pipe must be at least equal to the inner diameter of the opening made to the plenum chamber bottom 10, the pipe diameter may be made slightly larger conically expanding in the downward direction. The diameter of the plenum chamber bottom opening may not be made larger than the maximum diameter of the feeder tube mouth 8. The gate valve 6 is driven by an actuator 7. Since all dryers, boilers and similar equipment are conventionally operated pressurized above the ambient pressure, the discharge pipe 9 must be provided with a pressure lock, e.g., a dual valve to permit removal of accumulated scrap material from the discharge pipe under pressure. Transferred materials and particularly solid fuels may contain appreciably high amounts of impurities such as sand and small rocks. Further, the fluidizing solids medium of a circulating fluidized dryer may contain coked soot aggregates and similar particulates formed during heating. If these impurities are heavier than the particulate material being fed, the impurities will fall via the diffuser mouth 8 of the feeder tube 1 into the discharge pipe 9, wherefrom they can be removed periodically via the gate valve 6. In this embodiment, the impurities are prevented from filling the plenum chamber 3 and thus plugging the gap between the rim 11 of the feeder tube mouth and the bottom of the plenum chamber. The plenum chamber bottom

10 is easy to clean with a rod or similar scraping device equipped with a manual control or automatic actuator, thus avoiding operating disturbances due to accumulation of soot or other debris. The cleaning operation can be carried out without affecting the function of the apparatus or disconnecting the infeed of material.

In the operation of the apparatus, the carrier gas is blown into the plenum chamber 3 , where the gas flows uniformly about the mouth 8 of the feeder tube, and as the gas flows into the tube over the curved rim of the mouth, the gas velocity increases slightly, whereby a substantially constant velocity profile is attained in the feeder tube 1 with the largest velocity occurring close to the wall of the feeder tube 1. The solids infeed pipe 4 can be placed close to the lower end of the feeder tube 1, because the carrier gas flow is laminar almost immediately after its entrance into the mouth 8 of the feeder tube. Hence, the minimum height of the feeder equipment is determined by the height of the plenum chamber 3 plus the dimensions of the infeed nozzle 4 of the material being fed. In practice, however, the material infeed nozzle is preferably adapted at a distance above the plenum chamber 3 , thus preventing the turbulent inflow of the material being fed from reaching the curved area of the feeder tube mouth 8, and thereby, possibly escaping the feeder tube 1.

In Fig. 2 is shown a fluidized-bed boiler in which a portion of the fluidizing gas entering the fluidized-bed zone is fed using the assembly according to the inven- tion. The bottom of the boiler 16 is provided with a gas distribution nozzle base plate 18 having thereunder adapted a plenum chamber 17, wherefrom the fluidizing gas is fed to gas distribution nozzles 13 which provide the upward flow suspending the fluidized bed in the boiler 16. Into the plenum chamber 17, the gas fed via the feeder channel 5 from a fan 15. The center of the distribution nozzle base plate 18 is equipped with an assembly according to the invention having the upper end of the feeder tube 1 adapted to exit above the nozzle plate 18. The plenum chamber 3 is placed in the actual plenum chamber 17 of the boiler and the gas flow required for fluidization is generated by means of a fan 15, passed therefrom into the plenum chamber 17 and further via adjustable control vanes 24 into the actual boiler plenum chamber. The gas infeed of the distribution nozzles 13 is separated by means of the vanes 24 from the gas circuit of the gas infeed pipe 1, thus permitting the varying agitation of the fluidized bed through adjusting different gas flow rates per unit surface area. Under the mouth 8 of the feeder tube 1 is adapted a discharge pipe 9 via which' mpurity solids can be removed and further transferred away by means of a screw conveyor 12. The fuel is fed into the boiler 16 from a container 20, while the secondary air is passed via a duct 14 from a fan 19. The convective heat-transfer section 21 of the boiler 16 with heat exchangers 22 may be implemented in a conven- tional manner. From the convective heat-transfer section 21, the flue gases are passed into a stack 23 or the emission-control equipment. A fluidized-bed dryer can be realized in a similar fashion, whereby the design of the dryer chamber corresponds to that of the boiler firebox. Then, the gas distribution nozzle base plate and the assembly according to the invention may be arranged as described above.

In Fig. 3 is shown a construction having the distribution of the carrier gas into the large-diameter tube 1 enhanced by using two diffuser parts 8, 25 adapted in series so that, underneath the diffuser section 8 formed to the lower end of the tube, is mounted a separate diffuser 25 of a smaller size. Over the separate diffuser 25 is adapted a flat, annular baffle plate 26, which forms a gas infeed gap with the diffuser mouth 8 of the lower end of the feeder tube in the same fashion as the plenum chamber bottom 10 forms with the mouth rim 11 of the lower diffuser. The annular baffle must have an outer diameter extending at least over the area covered by the rim 11 of the upper diffuser 8, and the shape of the baffle is advantageously rotationally symmetrical.

In Fig. 4 is shown an FCC cracking reactor used in the oil refining industry. The gas is fed into the reaction space of this embodiment via an assembly according to the invention. The gas may be an inert gas whose only function is to agitate the contents of the reactor, or alternatively, the gas serves to control the reactor temperature or may participate the reactions of the process. An- equivalent unit can also be employed, e.g., as a polyethylene polymerization reactor, whereby the gas fed into the reactor is steam.

In addition to those described above, the present invention may have alternative embodiments. While the assembly according to the invention operates optimally in a vertical position, it can provide a laminar gas flow into a feeder tube in any position. While mixing a particulate material into a carrier gas flow causes limitations in the permissible range of operating positions, it is plausible that the assembly will function satisfactorily both in a position slightly tilted from the vertical as well as in a fully horizonal position. In positions different from the vertical, any reference to the bottom of the plenum chamber must be understood so as to concern the surface which faces the diffuser mouth 8.

Obviously, the dimensioning of the apparatus is dependent on the type of material being fed and the volume rates of the material. Gas flow velocity at the curved diffuser mouth and in the vicinity of the feeder tube wall can be affected by altering the radius of curvature of the mouth section. Herein, it is essential that the profile of the mouth section has no discontinuities and is smoothly curved, thus allowing the flow to pass maximally smoothly over the curved section, whereby the laminar flow will also extend into the feeder tube proper. As the carrier gas flow velocity must be adjusted to a correct value in the feeder tube, the design of the apparatus may require alterations for use with different materials. A simple design rule is to make the flow area across the gap of cylindrical cross section, which is formed between the plenum chamber bottom or equivalent baffle plate, to be equal to the cross-sectional flow area of the entrance section of the feeder tube mouth. While the curved part of the diffuser mouth should be made as shallow as possible, the flow will refuse to follow a curved surface of a too abrupt curvature, whereby the curved rim begins to act as a sharp corner. As the radius of curvature of the mouth section must be made larger for feeder tubes of larger diameter, it is obvious that the height of the assembly will become larger for equipment of large tube diameter.

An experimental system constructed according to the following design rules were found particularly functional:

- distance of mouth rim from plenum chamber bottom 65 mm

- plenum chamber height 400 mm

- inner diameter of mouth entrance section 390 mm

- radius of curvature of mouth section 100 mm

The experimental system was intended to serve a flash dryer .

Claims

Claims :

1. An assembly for forming a laminar gas flow for transporting granulated solids particulate matter, said assembly comprising

- a plenum chamber (3) forming a closed space containing a gas infeed pipe (5) for blowing gas into the plenum chamber, and

- a feeder pipe (1) into which said laminar flow is to be formed and whose one end (2) is adapted into said plenum chamber,

c h a r a c t e r i z e d in that

- said lower end (2) of said feeder tube (1) adapted into said plenum chamber (3) is formed into a mouth (8) of rotationally symmetrical shape having its inner diameter flared in a horn-like manner so that the inner diameter of the tube end is expanded smoothly toward the rim of its mouth facing the bottom of said plenum chamber (3) , and

- the bottom (10) of said plenum chamber (3) at the area facing said mouth (8) is adapted at a constant distance from the rim of said mouth (8) over the area facing the perimeter of the mouth and the bottom is adapted to cover an area which extends from an area remote to the outermost rim (11) of said mouth (8) radially inward to at least the point facing said rim (11) .

2. An assembly as defined in claim 1, c h a r a c t e r i z e d by an infeed nozzle (4) mounted on the feeder tube (1) , at a section of said tube (l) extending outward from said plenum chamber, said nozzle serving for the infeed of solids into said feeder tube and the -mixing of said solids into the carrier gas flowing in said feeder tube {l).

3. An assembly as defined in claim 1 or 2 , c h a r a c t e r i z e d by a discharge pipe (9) with a pressure lock, adapted to the bottom (10) of said plenum chamber (3) , under said diffuser mouth (8) , the inner diameter of said discharge pipe being at least equal to the inner diameter of the opening made to the bottom of said plenum chamber (3) .

4. An assembly as defined in any foregoing claim, c h a r a c t e r i z e d in that said discharge pipe

(9) is closed with a pressure lock comprising two series- connected valves (6) .

5. An assembly as defined in claim 1 for use in a fluidized-bed combustion boiler (16), said boiler comprising

- a boiler chamber containing a fluidized bed,

- a gas distribution nozzle base plate (18) adapted on the boiler chamber bottom with a plurality of gas distribution nozzles (13) mounted thereon serving to inject gas into said boiler (16) so as to suspend the fluidized bed therein, and

- a plenum chamber (17) located below said distribution nozzle base plate (18) for feeding gas into said distribution nozzles (13) that suspend the fluidized bed in said boiler chamber

(16), c h a r a c t e r i z e d in that

- said plenum chamber (3) is adapted into the actual plenum chamber (17) of the boiler, and

- said feeder tube (1) is mounted on said gas distribution nozzle base plate (18) so that the upper end of the tube extends above said distribution nozzle base plate (18) .

6. An assembly as defined in claim 1 for use in a fluidized-bed dryer, said dryer comprising

- a dryer chamber containing a fluidized bed,

- a gas distribution nozzle base plate adapted on the bottom of said dryer chamber bottom with a plurality of distribution nozzles mounted said base plate serving to inject gas into said dryer so as to suspend the fluidized bed therein, and

- a plenum chamber located below said gas distribution nozzle base plate for feeding gas into said distribution nozzles that suspend the fluidized bed in said dryer chamber,

c h a r a c t e r i z e d in that

- said plenum chamber is adapted into the actual plenum chamber of the dryer, and

7. An assembly as defined in claim 2 for use as the feeder device of a flash dryer, c h a r a c t e r i z e d in that said feeder tube (1) acts as the lower end of the dryer tube of said dryer and the solids infeed nozzle (4) is connected to the circulating bed material circuit of a fluidized-bed boiler at such a point as the bed material separating unit, e.g., a cyclone, or directly to the fluidized-bed zone of the boiler.

8. An assembly as defined in claim 7, c h a r a c t e r i z e d in that at least a portion of the heat energy used in the drying process is introduced into the dryer as the heat of the carrier gas blown into said plenum chamber (3) .

9. An assembly as defined in any of foregoing claims, c h a r a c t e r i z e d by a separate diffuser (25) of smaller size adapted underneath the diffuser mouth section (8) formed to the lower end of the feeder tube (1) , said separate diffuser comprising a diffuser element proper and a flat, annular baffle plate (26) , adapted at a distance below the overlying diffuser mouth of the feeder tube.

10. An assembly as defined in claim 1, c h a r a c t e r i z e d in that said assembly is adapted to perform as the gas inlet nozzle of a chemical reactor.