Dust cyclone with secondary separator, method of amplfication a rotary flow within a vutex finder and use of the dust cyclone and apparatus

Abstract

The present invention relates to a dust cyclone with secondary separation, characterized in that internals for strengthening the vortex flow are provided in the immersion tube.

Description

Technical field of the invention

[0001] The present invention relates to a dust cyclone for secondary or fine particle separation, a method for intensifying a rotational flow within a dip tube of such a dust cyclone, and the use of such a dust cyclone within a system for carrying out a fluidized bed process, which is operated in particular as a fluidized bed gasification, e.g., a high-temperature Winkler gasification (HTW). Furthermore, the invention relates to a system for carrying out a fluidized bed process, which includes such a dust cyclone. Description

[0002] Centrifugal dust collection is low-maintenance compared to other technologies, relatively insensitive to high temperatures, and inexpensive. It represents an important and interesting process step in both air pollution control and product recovery in industrial processes. Examples of particular economic significance include the dust collection of various extracted gas streams in the processing and steel industries, as well as recirculation cyclones (hereinafter also referred to as dust cyclones) in fluidized bed gasification and combustion.

[0003] Cyclones, or dust cyclones, have long been used to separate solid particles from gases. A cyclone essentially consists of a cylindrical upper section and a conical lower section. The dust- or solid-containing gas (also referred to as a gas-solid mixture) enters a rotationally symmetrical separation chamber tangentially, radially, or spirally. In a rotational flow, the gas stream is guided downwards in a spiral pattern to the solids outlet and then rises again in a further internal vortex within the cyclone. Such a vortex pattern is known and is shown for illustrative purposes in Fig. 9 shown. The purified gas flows back out of the cyclone via the dip tube located centrally in the cylindrical upper part.

[0004] As a result of the rotational flow and the resulting centrifugal forces, the heavier solid particles of the gas-solid mixture are forced towards the outer surface. Due to their own weight, as well as the boundary layer flow near the wall, which spirals towards the dust discharge, the dust is carried via the solids discharge into the dust collection container. The radially inward-flowing gas stream exerts a drag force on the particles, which counteracts the centrifugal force. If the centrifugal force is greater than the drag force, a particle moves towards the outer surface of the cyclone or dust cyclone and is separated. Above a certain particle size, the inward-directed drag force outweighs the centrifugal force. This particle size is called the "limit particle size".The limiting particle size is generally 30 to 50 µm, although the exact value within this range depends on factors such as cyclone geometry, flow velocity, particle shape and density, and gas viscosity. If this particle size is not met, the particle is no longer separated from the gas stream but instead flows out of the dip tube. Typically, the separation efficiency of such a centrifugal separator is 95%, for example, in the case of high-temperature gasification (HTW). In other words, approximately 5% of the particles, which usually fall below the limiting particle size, leave the centrifugal separator with the gas stream via the dip tube. This means that as dust fineness increases, the separation efficiency of the centrifugal separator decreases, necessitating further, costly post-separation using filter cartridges or electrostatic precipitators.

[0005] Another disadvantage is that the operating range of centrifugal separators is narrowly limited.

[0006] Observing the flow within the dip tube of a cyclone, one notices strong vortex formation within the tube, which moves the remaining particles in the gas against the tube wall. The central area of ​​the dip tube is almost dust-free.

[0007] In DE 2058674, it is proposed that "it is advantageous to draw off the dust-free central clean gas stream through an additional pipe of smaller diameter arranged inside the immersion tube. This reduces the filter area required for the subsequent cleaning of the remaining particle-laden gas stream. A disadvantage of this approach is that, if the gas is a product gas, handling becomes more complex."

[0008] German patent DE 1245267 proposes using several separate auxiliary gas nozzles within the immersion tube for the subsequent separation of fine particles. However, this approach is cumbersome to implement, and in many cases, the use of an external gas (auxiliary gas) is undesirable.

[0009] German patent DE 2361995 proposes that, in addition to the axial opening, the immersion tube be provided with further gas inlet openings around its circumference. A disadvantage of this approach is that a portion of the particle-laden boundary layer flow would immediately penetrate from the cyclone cover into the lateral openings of the immersion tube; therefore, this measure is considered ineffective.

[0010] In DE 6805593, it is further proposed that the immersion tube have an external stiffening element that is helically shaped. However, this does not allow for the separation of fine dust that is still present in the exiting gas stream.

[0011] Muschelknautz et al. propose in VGB Power Tech 04 / 2014 that the immersion tube of a recirculation cyclone be equipped with a guide vane assembly. This assembly consists of a rotationally symmetrical core with welded-on curved guide vanes. The guide vanes convert the turbulent flow entering the immersion tube into a purely axial flow with minimal loss.

[0012] All the measures proposed here aim to reduce the pressure loss of the centrifugal separator by eliminating the rotational flow in the immersion tube, but without being able to separate the remaining fine particles, i.e., particles below the limiting particle size, which are smaller than 50 µm, preferably smaller than 30 µm, and particularly preferably smaller than 10 µm. With known cyclones, such as those used in fluidized bed gasification, especially in high-temperature water (HTW) gasification, particles smaller than 30 µm cannot be separated by a conventional cyclone. These particles then have to be separated in downstream additional equipment (candle filters, electrostatic precipitators, etc.), which is costly.

[0013] KR 2003 0059857 A discloses a cyclone dust separator having a second separator on the upper side of an outlet hole.

[0014] DE 189 329 C discloses a dust removal device for gases that acts by centrifugal force.

[0015] US 2 754 970 A discloses a fluid separator.

[0016] WO 2020 / 169752 A1 discloses a dip tube for a cyclone separator.

[0017] WO 97 / 46323 A1 discloses a cyclone separator.

[0018] The purpose of the invention is to improve dust removal in the cyclone.

[0019] This improvement is achieved according to the invention by providing internal components in the immersion tube of a cyclone to enhance the vortex flow. Therefore, the invention relates to a dust cyclone according to claim 1. In other words, the internal components in the immersion tube are designed to enhance a vortex flow, or—in yet another way—to increase a tangential component of the vortex flow velocity. The dust cyclone according to the invention essentially consists of a cylindrical upper part and a conical lower part. The dust-laden gas enters a rotationally symmetrical separation chamber tangentially, radially, or spirally. In rotational flow, the gas stream is guided spirally downwards into the conical lower part to the solids bunker or an outlet and rises again in a further internal vortex within the dust cyclone. Such a vortex profile is also shown schematically in Fig. 9The diagram shows the interior of a dust cyclone without internal components in the immersion tube. The gas-solid mixture containing the fine particles is guided through the immersion tube of the dust cyclone, which is centrally located in the cylindrical upper section. The gas-solid mixture then encounters the internal components in the immersion tube to enhance the vortex flow. The immersion tube is typically arranged along a vertical axis that runs centrally with respect to the cylindrical upper section of the dust cyclone. The immersion tube projects into the interior of the cylindrical upper section, is essentially straight, and its internal volume is fluidically connected to a clean gas outlet of the cyclone in the upstream direction, i.e., at an upper end of the cylindrical upper section. The immersion tube can be, for example, cylindrical or conical.

[0020] The internal components of the immersion tube can be designed in various ways. The only important factor is that these components are designed to increase the tangential component of the velocity of the incoming rotary flow of the rising gas-solid mixture containing the fine particles (i.e., without the previously separated coarse particles). In other words, these components are internal resistances within the immersion tube, designed to increase the tangential component of the velocity of the incoming rotary flow or to intensify the incoming vortex flow.

[0021] Here, the term "secondary separation" means, in particular, that in addition to the conventional particle separation described above in the lower conical part of the dust cyclone (i.e., primary separation of particles, i.e., coarse particles that do not fall below the limiting particle size), a separation of fine particles takes place in the cylindrical upper part after passing through the dip tube and its internal components. Secondary separation, as defined, can be carried out if the gas-solid mixture has sufficient tangential momentum. For this reason, axial and / or radial guide elements, i.e., "axial swirlers," are arranged in the dip tube of the cyclone. The role of these guide elements is to increase the tangential component of the velocity of the gas-solid mixture within the dip tube.

[0022] The invention ensures that the vortex flow is not converted into an axial flow, but is intensified within the immersion tube in order to achieve extensive complete separation of fine particles.

[0023] In one embodiment of the invention, the internal components in the immersion tube are designed as tangential or axial guide elements. Specifically, "tangential guide elements" are surface structures on the surface of the inner wall of the immersion tube, designed to enhance the incoming vortex flow, as described above, by increasing the tangential component of the velocity. Specifically, "axial guide elements" are structures arranged centrally in the immersion tube, designed to enhance the incoming vortex flow. Increased fine particle separation can be achieved through the use of tangential or axial guide elements.

[0024] In further embodiments of the invention, the internal components are designed as vortex generators or turbulators to enhance the vortex flow within the immersion tube. Increased fine particle separation can also be achieved through the use of vortex generators or turbulators. The turbulators are alternatively referred to as "axial swirlers," a term familiar to those skilled in the art.

[0025] The separation of fine particles is also aided by the fact that the immersion tube can be provided with slots around its circumference, particularly around the circumference of the immersion tube outlet, as is also provided for in one embodiment of the invention. Such slots are preferably arranged upstream of the internal components. Within this description, the term "upstream" or "upstream direction" refers to the upward flow direction of the gas (or gas-solid mixture) at the immersion tube outlet, as, for example, in Fig. 1 with reference 3 or in Fig. 9 shown by the inner vortex. The downward flow towards the conical solids outlet in the lower part of the cyclone, as shown in Fig. 1 with reference 4 or in Fig. 9The element shown is disregarded for this definition. Alternatively or additionally, a deflector can be arranged upstream of the internals. The deflector allows the fine particles of the gas-solid mixture, whose vortex flow or tangential velocity component has been intensified by the internals, to be extracted or separated from the immersion tube by centrifugal forces. Additionally or alternatively, a deflector for the fine particles can be provided at the upper end of the immersion tube, i.e., in the upstream direction. This deflector typically has a cylindrical collar, e.g., in the form of a tube, that engages the immersion tube, leaving an annular gap. This arrangement of the deflector is located upstream of the internal(s) to intensify the tangential velocity component.In this case, the annular gap is defined by the wall surface of the interior of the dip tube and the outer wall surface of the deflector collar. In other words, the collar has a smaller outer diameter than the inner diameter of the dip tube and projects into the dip tube. The dip tube can then be surrounded by an annular space, which may be part of the deflector and is fluidically connected to the interior of the dip tube via the annular gap. The annular space is defined by the outer wall surface of the collar, the outer wall surface of the dip tube, and other wall surfaces that form an annular space closed to the outside—except for a solids outlet and the annular gap.When the fine particles are guided through the dip tube after flow intensification by the internal components, they can be directed into the annular space via the annular gap defined by the deflector element and its collar, where they are separated. The annular space may have an outlet from which the fine particles can be extracted. Furthermore, the collar of the deflector element is designed such that it, together with the dip tube, defines an outlet channel in the upstream direction. In other words, the gas, completely or partially purified of the fine particles—i.e., the clean gas—can ultimately leave the dust cyclone via this outlet channel.Thus, one embodiment according to the invention relates to the dust cyclone according to the first aspect of the invention, characterized in that a deflecting element is arranged at an upper end of the immersion tube in the upstream direction of the gas flow and upstream of the internals, which is designed to separate dust particles from the upward vortex and the deflecting element simultaneously defines an opening which is designed to discharge a clean gas, i.e. a gas after complete or partial separation of the fine particles, from the dust cyclone or the end of the immersion tube.

[0026] A flow straightener is preferably arranged on an inner wall of the collar of the deflecting element. This flow straightener is designed to reduce the rotational flow of the clean gas and its pressure loss. The flow straightener can, for example, have star-shaped and / or cross-shaped structures, as known from US 6,679,930 B1. Flow straighteners are generally known to those skilled in the art. This contributes to efficient process control. The flow straightener is particularly well-positioned upstream of the internal components.

[0027] The dust cyclone according to the invention can be arranged vertically, at an angle or horizontally with respect to the earth's surface for operation within a system.

[0028] In particular, the dust cyclone according to the invention can be used in a fluidized bed process, especially in a fluidized bed gasification process, e.g. in an HTW process.

[0029] In one embodiment, the deflecting element has a collar whose inner surface cylindrically surrounds the opening of the clean gas outlet and engages with or spans the dip tube, thus defining an annular gap between the dip tube and the collar. The collar is therefore designed as a cylindrical element, e.g., a tube. As described above, the collar is positioned upstream of the internal components. In this way, the fine particles, as part of the gas-solid mixture, which are in an enhanced upward flow through the dip tube as previously described, can exit the dip tube through this annular gap, while the clean gas can leave the dust cyclone through the opening defined by the deflecting element. Preferably, an inner surface of the collar is designed upstream of the particle separation point.A rectifier is arranged within the annular gap, designed to reduce the rotational flow of a clean gas and any pressure loss. The rectifier is thus also located upstream of the internal components in the upper part of the dust cyclone.

[0030] In one embodiment, an outer surface of the dust cyclone can be surrounded by a shell cyclone, i.e., a casing in the form of a larger cyclone, thereby defining a cyclone outer space. This outer space is configured to guide separated fine particles through it. In other words, the dust cyclone is surrounded by another cyclone whose inner diameter is larger than the outer diameter of the dust cyclone. The dust cyclone is thus completely enclosed by the shell cyclone. In particular, the resulting outer cyclone can have fluidic communication between the annular space described above and the dust outlet at the bottom of the cyclone. This allows fine particles separated by the dip tube and the deflector to be guided through the outer cyclone to the dust outlet at the bottom of the dust cyclone. Normally, only coarse particles, i.e.,Particles that meet at least the limit particle size are separated. In this embodiment, the outer cyclone and the external space defined by it can also guide the finest particles to this outlet. Advantageously, no additional return lines to the fluidized bed of a carburetor are required. Thus, such a shell cyclone is beneficial to process economy and process costs can be reduced. For example, if the dust cyclone is used in a fluidized bed process, essentially all particles can be returned to the fluidized bed in this way. Additionally or alternatively, the cyclone's outer space can be designed so that the separated fine particles can be discharged via an external outlet located between the upper end of the upper part and the lower end of the lower part of the dust cyclone.

[0031] The following aspects of the invention include the features and advantages of the dust cyclone described above according to the first aspect of the invention.

[0032] According to a second aspect, the present invention relates to a method for increasing the rotational flow within the immersion tube comprising the step of guiding a gas-solid mixture through a dust cyclone according to the first aspect of the present invention.

[0033] According to a third aspect, the present invention relates to the use of the dust cyclone according to the first aspect of the present invention in a plant for carrying out fluidized bed gasification, in particular an HTW process, or its use in a fluidized bed gasification process, in particular an HTW process. In this case, the inlet of the dust cyclone is arranged downstream of the fluidized bed gasifier, in particular the HTW gasifier, and is directly connected to the outlet of the fluidized bed gasifier, in particular the HTW gasifier.

[0034] According to a fourth aspect, the present invention relates to a plant for carrying out fluidized bed gasification, in particular an HTW process, wherein the plant comprises a dust cyclone according to the first aspect of the invention. Drawings

[0035] Further advantages, details and features of the invention will also become apparent from the following description and from the drawings; these show in Fig. 1 a simplified sectional drawing through a dust cyclone according to the invention; Figs. 2-4 Immersion tubes with internal components according to the invention for vortex formation; Fig. 5 an embodiment of a dip tube according to the invention for arrangement in a dust cyclone according to the invention; Fig. 6 a first variant of the dust cyclone according to the invention with a mantle cyclone; Fig. 7 a second variant of the dust cyclone according to the invention with a shell cyclone with an associated sectional drawing AA and BB; Fig. 8 a third variant of the dust cyclone according to the invention with a mantle cyclone; as well as Fig. 9 A diagram illustrating the course of a vortex flow within a dust cyclone in front of the dip tube.

[0036] The in Fig. 1In the dust cyclone generally designated (1), the gas / solid mixture is introduced via an inlet ( 2 ) is supplied. After dust separation, the purified gas leaves the cyclone ( 1 ) via the outlet ( 3 The dust outlet is symbolically marked with an arrow ( 4 ) designated.

[0037] In the cylindrical upper part of the cyclone ( 1 ) is a dip tube ( 5 ) arranged centrally, at the upper end of which a deflecting element ( 6 ) is provided, with its collar ( 7 ) releasing an annular gap into the immersion tube ( 5 ) intervenes.

[0038] Fine particles, which are carried upwards in the area of ​​the inner wall of the immersion tube due to a vortex flow, are deflected via the deflecting element ( 6 ) into a dip tube ( 5 ) surrounding annular space ( 8 ) is conveyed and from there via an outlet ( 9 ).

[0039] The immersion tube is used to generate and intensify the vortex flow ( 5 ) with a built-in element ( 10 ) equipped. In Fig. 2 schematically, this is a tangential guide element ( 11 ) indicated. Fig. 3 indicates an axial guide element ( 12 ) on, while Fig. 4 a turbulator as a guiding element ( 13 ) shows. The flow patterns of the vortex flow are indicated by corresponding arrows inside the respective immersion tubes (5).

[0040] Fig. 5 shows a specific embodiment of a dip tube (5) according to the invention, as it is used in a cyclone (1) according to the invention. Fig. 1A gas-solid mixture of gas and fine particles (15) enters the dip tube (5) and passes through internal components (10a), which increase the tangential component of the velocity of the gas-solid mixture, or of the mixture of gas and fine particles (16). Downstream of the internal components is the collar (7) of the deflecting element (6) (not fully shown), which, as described above, engages in the dip tube (5). Due to the rotational flow, fine particles, indicated by the arrows (16), are separated at the annular gap between the inner wall of the dip tube and the outer wall of the collar (7) of the deflecting element (6) (not fully shown). Pure gas remains. At the lower end of the collar (7) of the deflecting element (6) are rectifiers (14) designed to reduce the rotational flow of the pure gas and the pressure drop.After the clean gas has passed through the rectifiers (14), it leaves the dust cyclone (1) via the outlet (3).

[0041] Figs. 6-8 Figures 1a-1c show special variants of the dust cyclone according to the invention. These variants (1a-1c) contain components that have already been explained for the previous figures and therefore do not require further explanation here. The large arrow in Figs. 6-8 shows the flow direction of the gas-solid mixture containing coarse particles (23) and fine particles (16) after entering the respective cyclone (sa outer vortex in Fig. 9 ). Fine particles (16) and coarse particles (23), which have at least the limiting particle size, are also shown. Figs. 6-8It is also shown that the fine particles (16) in the upper part of variants (1a-1c) are separated due to the intensification of the vortex flow by the axial guide element (12) and the deflecting element (6). Coarse particles (23), on the other hand, are separated by the downward flow in the conical lower part of the respective cyclone. Fig. 6 Figure 1a shows a first variant of the dust cyclone (1) according to the invention. Here, a dust cyclone (1), such as in [reference to figure], is used. Fig. 1The dust cyclone (1) is surrounded by a shell cyclone (21), wherein the inner diameter of the shell cyclone (21) is larger at the respective points than the outer diameter of the dust cyclone (1). This defines a cyclone outer space (25) between the shell cyclone (21) and the dust cyclone (1), which cyclically surrounds the dust cyclone (1) and into which the separated fine particles (16) are introduced during separation. Here, the cyclone outer space (25) is in fluidic communication with the solids outlet (4) on the conical lower part of the dust cyclone according to the first variant (1a). Furthermore, the cyclone outer space (25) is in fluidic communication with the annular space (8) into which the fine particles (16) are separated. Thus, the separated fine particles (16) can also be discharged via the dust outlet (4). An alternative and second variant (1b) of the dust cyclone according to the invention is shown in Fig. 7shown. The second variant (1b) differs from the first variant (1b) in that the collar (7) of the deflection element (6) does not engage in the immersion tube (5), but spans the immersion tube (5) to define an annular gap. Fig. 8 Figure 1c shows a third variant in which the outer cyclone chamber (25) is not fluidically connected to the dust outlet (4) on the conical lower part. However, in the dust cyclone according to the third variant (1c), there is a first and second outer outlet (27a, 27b) from the outer cyclone chamber (25), which can serve both as a solids outlet for the fine particles (16) and as a gas outlet. The path of the fine particles or the secondary gas is indicated by dashed lines.

[0042] By incorporating internal components within the immersion tube and removing particles at its circumference, the vortex flow is not transformed into an axial flow; rather, the vortex flow within the immersion tube is intensified to achieve comprehensive and complete separation, even of the finest particles. This measure also expands the operating range of the cyclones.

[0043] As mentioned at the outset, the separation of fine particles using the dust cyclone according to the invention largely eliminates the need for filter cartridges or electrostatic precipitators, which are otherwise required downstream of a dust cyclone for fine particle separation, particularly in the case of a fluidized bed gasification process, e.g., an HTW process. This eliminates the need for additional process components, resulting in significant cost savings.

[0044] Fig. 1Figure 1 shows a centrifugal separator with a device for increasing the vortex flow within the dip tube (vortex generator). The dip tube can be either cylindrical or conical; the only important aspects are increasing the rotational flow within the dip tube and removing the separated fine particles via slots around the circumference of the dip tube outlet.

[0045] Of course, the examples described can be modified and supplemented in many ways without abandoning the basic idea of ​​the invention. Thus, the invention also relates to the method for intensifying the rotational flow within the immersion tube using the measures described above or similar ones. Experiments

[0046] Separation tests were conducted using a Plexiglas cyclone. The setup was designed such that dust, consisting of particles, was added to the gas flow at the cyclone inlet. The aim was to investigate whether the dust could be separated from the gas within the cyclone. A fine filter was installed downstream of the cyclone, i.e., at its clean gas outlet. This type of setup corresponds to a previously known cyclone from the art. The particles consisted of cement with particle sizes between 1 and 100 µm. These particles are comparable to solid particles that are introduced into a recirculation cyclone from the HTW gasifier in an HTW gasification process.

[0047] Initially, tests were conducted with a dip tube without internal components as a comparative test; i.e., in accordance with the state of the art. In these tests, particle residues were still found behind the cyclone in the fine filter.

[0048] The same experimental setup was carried out with a dust cyclone according to the invention, with the difference that in the dust cyclone according to the invention, internal components according to the invention were arranged inside the immersion tube, which are designed to increase the tangential component of the velocity of the gas-solid mixture. In these separation tests with a dust cyclone according to the invention with internal components according to Fig. 3 No dust was visible in the fine filter behind the cyclone within the immersion tube. This means that the separation efficiency of the dust cyclone according to the invention is higher than that of a cyclone known in the prior art without the described internal components. The separated dust could be found in an annular space surrounding the immersion tube.

[0049] Furthermore, without being bound to any particular theory, it can be assumed based on the experiments above that the significant increase in gas velocity in the rotating flow within the immersion tube by the internals results in the additional separation of fine particles, which fall below the limiting particle size during normal separation in a known cyclone.

Claims

1. Dust cyclone with secondary separation, characterized in that fittings (10, 11, 12, 13) for intensifying the swirling flow are provided in the immersion pipe (5), wherein a deflection element (6) is arranged at an upper end of the immersion pipe (5) in an upstream direction of a gas flow and upstream of the fittings, the deflection element (6) being configured to separate fine particles and at the same time defining an opening which is configured to discharge clean gas from the dust cyclone after separation of the fine particles, and wherein the deflection element (6) has a collar (7) whose inner surface cylindrically surrounds the opening and penetrates into the immersion pipe (5) or bridges over the immersion pipe (5), such that an annular gap is defined by the immersion pipe (5) and the collar (7).

2. Dust cyclone according to claim 1, characterized in that the fittings in the immersion pipe (5) are formed as tangential guide elements (11).

3. Dust cyclone according to claim 1, characterized in that the fittings in the immersion pipe (5) are formed as axial guide elements (12).

4. Dust cyclone according to any one of the preceding claims, characterized in that the fittings in the immersion pipe (5) are formed as turbulators (13) or vortex generators.

5. Dust cyclone according to claims 3 and 4, characterized in that the immersion pipe (5) is provided with slots (7) on its circumference for discharging the separated fine dust.

6. Dust cyclone according to claim 1, wherein a straightener (14) is arranged on an inner surface of the collar (7), the straightener (14) being configured to reduce the rotational flow of a clean gas and a pressure loss.

7. Dust cyclone according to any one of claims 1 to 6, wherein an outer surface of the dust cyclone is surrounded by a jacket cyclone (21), thereby defining a cyclone outer space (25), and the cyclone outer space (25) is configured to conduct separated fine particles (16) therethrough.

8. Dust cyclone according to claim 7, wherein the cyclone outer space (25) is configured • to conduct separated fine particles from a cylindrical upper part of the dust cyclone to a dust outlet (4) at a conical lower part of the dust cyclone; and / or • wherein the cyclone outer space (25) is configured to discharge separated fine particles (16) from an outer outlet (27a, 27b), the outer outlet (27a, 27b) being arranged between the cylindrical upper part and the conical lower part of the dust cyclone.

9. Method for intensifying the rotational flow within the immersion pipe, comprising the step of conducting a gas-solid mixture containing fine particles through a dust cyclone according to any one of claims 1 to 8.

10. Use of the dust cyclone (1, 1a, 1b, 1c) according to any one of claims 1 to 8 in a plant for carrying out fluidized bed gasification.

11. Plant for carrying out fluidized bed gasification, wherein the plant comprises a dust cyclone according to any one of claims 1 to 8.

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