GB2437172A

GB2437172A - Centrifugal separator having linear compensation means

Info

Publication number: GB2437172A
Application number: GB0706990A
Authority: GB
Inventors: Martin Kienboeck; Wilhelm Bruckmann
Original assignee: Balcke Duerr GmbH
Current assignee: Balcke Duerr GmbH
Priority date: 2006-04-12
Filing date: 2007-04-11
Publication date: 2007-10-17
Anticipated expiration: 2027-04-11
Also published as: FR2899824A1; RU2006117009A; UA87289C2; GB0706990D0; CN100574845C; CN101053724A; RU2358791C2; GB2437172B; DE102006017306A1; FR2899824B1; DE102006017306B4

Abstract

The invention relates to a centrifugal separator 1 for separating fluid from a gas flow, especially for separating water from water vapour, comprising a first pipe 2 in which a swirl generator 6 is arranged and a subsequent second pipe 11. The inside diameter D1 of the second pipe 11 at a first end 12, which faces a first end 14 of a subsequent third pipe 13 arranged coaxially thereto, being larger than the outside diameter D2 of the third pipe 13 at its first end 14. The second pipe 11 and the third pipe 13 are enclosed by a jacket 17 at a radial distance by forming a separation chamber 16, which jacket is provided with a drainage 19 for the fluid. Because the centrifugal separator 1 comprises at least one linear compensator 50, the axial length L1, L2, L3 of the centrifugal separator 1 can be varied, so that simple retrofitting is enabled even under cramped conditions. The compensator may take the form of a bellows or a curve in the pipe.

Description

CENTRIFUGAL SEPARATOR FOR SEPARATING OFF A LIQUID

The invention relates to a centnfugal separator for separating fluid from a gas flow, especially for separating water from water vapor, with the features of the preamble of claim 1.

Such centrifugal separators are used for example in steam generation plants with steam connection lines and support the function of a conventional water separator/reheater. Such a conventional water separator is arranged between a high-pressure and low-pressure turbine and is used for drying the steam prior to the entrance into the low-pressure turbine. As a result of modifications in the system technology or the manner of driving a power plant it may occur that the steam supplied to the water separator/reheater no longer corresponds to the orignal configuration, so that additional heating steam is required for evaporating the residual humidity or "wets steam Will flow into the low-pressure turbine. The plant output will decrease and erosion and corrosion problems may occur in the downstream plant components. With an additional centrifugal separator as disdosed for example in DE 10129198 B4 it is possible to achieve a further separation of water in a reliable and economical manner. A further and reliable water separation can also be achieved with high-speed separators of different configurations 5uCh as in EP 0002235 Al or EP 0233332.

Difficulties can occur however when existing plants are to be retrofitted. The available installation space is often very limited, so that additional water separators with an only relatively weak dimensioning can be used. The goal to increase the efficiency of the plant is often not achieved in such a case.

The invention is therefore based on the object of forming a centrifugal separator of the kind mentioned above which even in the case of cramped conditions can be installed in a plant to be retrofitted, with the efficiency of the plant being increased in addition.

This object is achieved by the features of the independent claim. Advantageous embodiments of the invention are mentioned in the subordinate claims.

The centrifugal separator in accordance with the invention for separating fluid from a gas stream, especially for separating water from water vapor, comprises a first pipe in which a swirl generator is arranged and a subsequent second pipe, with the inside diameter of the second pipe at a first end which faces a first end of a subsequent third pipe arranged coaxially thereto being larger than the outside diameter of the third pipe at its first end, with the second pipe and the third pipe being endosed by a jacket at a radial distance by forming a separation chamber, which jacket is provided with a drainage for the fluid. Through the centrifugal separator in accordance with the invention the object is achieved in such a way that it comprises at least one linear compensator. This ensures that the axial length of the centrifugal separator can be varied depending on the available installation space. Retrofitting is thus easily possible, whereby a centrifugal separator can also be provided with sufficient dimensioning, so that an improved efficiency of the plant can be achieved.

Preferably, the linear compensator is a bellows or a bend or any other pipe fitting. This allows flexible adjustment to predetermined spatial conditions. A deflection of the axial direction of the centrifugal separator by 90 or more can be achieved espedally by a knee, so that a large axial length of the centrifugal separator is enabled at low overall size. The arrangement of a linear compensator between the first and second pipe is appropriate. In such a case, the first pipe including the swirl generator can be used as a first module and the second pipe as well as the third pipe including the separation chamber as a second module. The linear compensator is then used as a connecting part between the two modules. Adjustment to the predetermined spatial conditions is thus easily possible by such a modular design. Moreover, modular parts can be dimensioned optimally depending on available overall space.

The first pipe can comprise at least one section which is arranged in a conical way, with the swirl generator being arranged in this section. As a result of the conical geometry, the axial speed of the inflowing steam is reduced, so that a lower pressure loss is obtained at the swirl generator and the efficiency of the centrifugal separator can be improved even further. This measure can be carried out * 3 * without influencing the axial overall size, so that retrofitting in the case of little overall space is easily possible.

According to a further embodiment of the invention, the second pipe and the third pipe are arranged at an axial distance from each other. The ratio of the axial distance to the inside diameter of the second pipe at its first end preferably lies in the range of 0.1 to 0.2. This ensures that the water droplets thrown by the swirl generator against the outside wall of the first pipe and the second pipe are reliably introduced into the separation chamber. When the centrifugal separator further comprises a flow straightener which is provided downstream of the first separation chamber, the flow of steam which has been relieved of water can be unswirled prior to exiting from the centrifugal separator.

For increasing the efficiency, an additional separation chamber can be provided after the above separation chamber which comprises a fourth pipe following the third pipe. The fourth pipe is followed by a coaxially arranged fifth pipe, with the fifth pipe being inseited at least partly in the fourth pipe in such a way that an annular gap is given between the fourth pipe and the fifth pipe.

The fourth pipe and the fifth pipe are enclosed at a radial distance by an additional jacket, so that an additional separation chamber is formed which is provided with a fluid discharge for discharging separated water. When the additional separation chamber is provided with a connection, the same can be used for applying a negative pressure in the additional separation chamber. The degree of separation and the efficiency can thus be improved even further. When an additional separation chamber is provided, a flow straightener can be provided downstream, so that an unswirled flow of steam will exit.

An effective measure for further improving the efficiency is to provide the swirl generator within the first pipe with swirl blades which extend from a swirl generator hub towards the inside wall of the first pipe and have a curved shape in their cross section. The curved shape is preferably arranged as a circular arc. The ratio between the radius of the circular arc and the inside diameter of the first pipe at a first end averted from the second pipe lies especially preferably in the range of 0.1 to 0.3. It has been noticed that a very efficient deflection of inflowing drops into the centrifugal separator can be achieved when the opening angle of the circular arc is in the range of 20 to 60 . It is advantageous in this context when the ratio between the inside diameter of the second pipe at the first end and the inside diameter of the first pipe at its first end lies in the range of 1.0 to 1.5.

An increase in the efficiency even in cramped conditions is. further enabled in such a way that the opening angle of the circular arc decreases from the swirl generator hub to the inside wall of the first pipe. As a result, a relatively strong swirling force is exerted on the drops flowing onto the swirl blades relative to the swirl generator hub in order to be conveyed against the inside wall of the first pipe.

Drops which meet the swirl blades relatively close to the inside waH of the first pipe doe not require such strong deflection forces, so that the circular arc can be provided with a smaller opening angle.

This leads in total to a lower pressure loss and an increase in the efficiency of the centrifugal separator. An alternative or additional measure is that the radius of the circular arc increases from the swirl generator hub to the inside wall of the first pipe.

The invention is now explained in closer detail by reference to embodiments shown in the drawings, wherein: Fig. 1 shows a schematic representation of a centrifugal separator with several modules in a longitudinal sectional view; Fig. 2 shows a top view of a swirl blade mounted on a swirl generator hub; Fig. 3 shows a perspective view of a first swirl blade, and Fig. 4 shows a perspective view of a second swirl blade.

Fig. 1 shows a schematic representation of a centrifugal separator 1 with several modules in a longitudinal sectional view. The centrifugal separator 1 comprises a first pipe 2 which comprises a conical section 3. In said section 3, several swirl blades 4 are arranged in a garland-like manner about the hub 5 and are rigidly connected with the hub and the inside wall of the enclosing first pipe 2.

The swirl blades 4 and the hub 5 jointly form a swirl generator 6. Once steam flows from the direction marked with arrow 40 from an upstream high-pressure turbine (not shown) into the first pipe 2 of the centrifugal separator 1, it meets the hub 5 and the swirl blades 4 arranged therein.

Water droplets are guided to the inside wall of the first pipe by means of the swirl blades 4 and can run off there. Hub 5 is provided with a hollow configuration and comprises a hub floor 7 which is sealed on the inflow side. The hub 5 is open on the opposite outflow side 8. A negative pressure forming there can be used in order to facilitate suction in following separator modules, as is explained below in closer detail.

The conical section 3 is provided upstream with a cylindrical connection element 9 which is used to enable the connection to an existing pipeline in a simple manner. The connedion element is provided for this purpose with the same diameter D as the pipeline to be connected. The conical section 3 is optionally provided downstream with a cylindrical section 10, so that mounting with subsequent cylindrical pipe parts can be performed easily. Said first pipe 2 can be handled as a single module, with the length of the subsequent components of the centrifugal separator not yet being determined.

The first pipe 2 is coupled with a second pipe 11 which comprises a first end 12. Said second pipe 11 which has an inside diameter Dl is followed by a third pipe 13 which is arranged coaxially to the second pipe 11 and which comprises a first end 14. It is appropriate to dimension the distance 15 between the first end 12 of the second pipe 11 and the first end 14 of the third pipe 13 in such a way that it has an amount which corresponds to 0.1 to 0.2 times the inside diameter Dl of the second pipe 11. The inside diameter Dl of the second pipe 11 is larger than the outside diameter D2 of the third pipe 13, so that the water which runs off the inside wall of the first pipe 2 and from there on the inside wall of the second pipe 11 can exit from the annular gap formed by the same and reaches a separation chamber 16.. The separation chamber 16 comprises a jacket 17 WhiCh encloses the second pipe 11 and the third pipe 13. Built-in parts 18 in the separation chamber 16 effectively hold off the steam flow from the collected water which can be removed by means of a water discharge 19 in the region of the floor 20 in the separation chamber 16. The steam thus substantially separated from the water flows into the third pipe 13 and can leave the centrifugal separator 1 at its opposite end.

A linear compensator 50 can be installed in the section IIAU (see Fig. 1) between the first pipe 2 and the second pipe 11. This can be a bellows or pipe-bend (the latter is not shown in Fig. 1), so that the relative position between the first pipe 2 as the first module and the separation chamber 16 as the second module can be adjusted to the on-site space conditions. The first pipe 2 can therefore optionally be coupled in an angular manner or with an axial offset with the separation chamber 16.

In order to increase the efficiency, an additional separation chamber 21 can follow the separation chamber 16, which additional separation chamber comprises a fourth pipe 22 and a fifth pipe 23 arranged coaxially thereto. The fifth pipe 23 is inserted at least partly into the fourth pipe 22 in such a way that an annular gap 24 is given between the fourth pipe 22 and the fifth pipe 23, so that water still present on the inside wall of the fourth pipe and running off there is able to collect and can reach the additional separation chamber 21. The additional separation chamber 21 is formed by the two pipes 22, 23 and a jacket 25 radially endosing the same, with the same comprising a water discharge 27 in the area of the floor 26 in order to enable the removal of the collected water. When the additional separation chamber 21 further comprises a connection 28, a suction line can be connected to the same in order to facilitate the suctioning off of the water from the fourth pipe 22.

The suction line is preferably connected with a return line 29 which is coupled with a hub extension as an extension of hub 5 within the first pipe 2. As a result, a negative pressure present on the outflow side 8 of hub 5 can thus be used in a useful way.

If only one separation chamber 16 is provided, a flow straightener 31 can optionally be connected downstream which causes an unswirling of the steam flow. The flow straightener 31 comprises swirl blades 32 which are fixedly mounted on a hub 33, with the sense of rotation of the swirl blades 32 of the flow straightener 31 being directed in opposition to the sense of rotation of the swirl blades 4 of the swirl generator 6. When a second separation chamber 21 is provided, the flow straightener 31 is provided downstream of said separation chamber 21. The dried steam leaves the flow straightener 31 in the direction of a downstream low-pressure turbine.

As is shown in Fig. 1, the length Li of a centrifugal separator which comprises a first pipe 2 as a first module and a separation chamber 16 as a second module can be varied by means of a linear compensator between the two modules in such a way that even in the case of cramped conditions the space can be utilized in an optimal manner. A linear compensator can also be provided optionally between the separation chamber 16 and the additional separation chamber 21, so that the length 12 of the centrifugal separator can be varied. This applies similarly for the space between a separation chamber 16, 21 and a downstream flow straightener 31, so that a length 13 can be set.

In order to increase the efficiency of a centrifugal separator 1, the swirl blades can have a shape which is curved in its cross section. This is preferably a circular arc, as is shown in Fig. 2. Fig. 2 shows a top view of a hub 5 of a swirl generator 6 and a swirl blade 4 (other swirl blades 4 that are present are not shown). The circular arc has a radius R which is preferably 0.1 to 0.3 times the amount of the diameter D of the connecting element 3 of the first pipe 2. The opening angle a of the swirl blade 4 lies preferably in the range of 200 to 60 . Water droplets which meet the swirl blade 4 from the direction of flow marked with arrow 40 are deflected by the curved shape in the direction towards the inside wall of the enclosing first pipe 2. Even higher efficiencies can be achieved when the swirl -7 * blades have an opening angle a which decreases from the swirl generator hub 5 in the direction towards the inside waH of the first pipe 2 (see Fig. 3). The angle decreases from cxl to a2. Another or further possibility is that the radius of the circular arc of a swirl blade 4 increases from the swirl generator hub 5 to the inside wall of the first pipe 2. Other configurations are also advantageous (see Fig. 4) in which a swirl blade 4 is shown with a constant opening angle cxl equal a2:. In the latter case the swirl blade 4 has the geometry of a conical section.

Claims

CLAIMS: 1. A centrifugal separator for separating fluid from a gas

flow, especially for separating water from water vapor, comprising a first pipe in which a swirl generator is arranged and a subsequent second pipe1 with the inside diameter of the second pipe at a first end which faces a first end of a subsequent third pipe arranged coaxially thereto being larger than the outside diameter of the third pipe at its first end, with the second pipe and the third pipe being enclosed by a jacket at a radial distance by forming a separation chambet which jacket is provided with a drainage for the fluid, characterized in that the centrifugal separator comprises at least one linear compensator in order to thus vary the axial length of the centrifugal separator.

2. A centrifugal separator according to daim 1, characterized in that the linear compensator is a bellows or a bend.

3. A centrifugal separator according to claim 2, characterized in that the linear compensator is arranged between the first pipe and the second pipe.

4. A centrifugal separator according to one of the claims 1 to 3, characterized in that the first pipe comprises at least one section which is arranged in a conical way1 with the swirl generator being arranged in this section.

5. A centrifugal separator according to one of the claims 1 to 4, characterized in that the second pipe and the third pipe are arranged at an axial distance from each other.

6. A centrifugal separator according to claim 5, characterized in that the ratio of the axial distance to the inside diameter of the second pipe at its first end lies in the range of 0.1 to 0.2.

7. A centrifugal separator according to one of the claims 1 to 6, characterized in that a flow straightener is provided which is provided downstream of the separation chamber. * 9

* 8. A centrifugal separator according to one of the claims 1 to 6, characterized in that a fourth pipe follows the third pipe, with a fifth pipe arranged coaxiaffy thereto following the fourth pipe and the fifth pipe being inserted at least partly into the fourth pipe in such a way that an annular gap is obtained between the fourth pipe and the fifth pipe, with the fourth pipe and the fifth pipe being enclosed at a radial distance from an additional jacket, so that an additional separation chamber is formed having a discharge for the fluid.

9. A centrifugal separator according to claim 8, characterized in that the additional separation chamber comprises a connection for applying a negative pressure in the additional separation chamber.

10. A centrifugal separator according to one of the daims 8 or 9, charactetized in that a flow straightener is provided which is provided downstream of the additional separation chamber.

11. A centrifugal separator according to one of the claims 1 to 10, characterized in that the swirl generator comprises swirl blades within the first pipe,extending from a swirl generator hub to the inside wall of the first pipe and having a curved shape in the cross section.

12. A centrifugal separator according to daim 11, characterized in that the curved shape is arranged as a circular arc.

13. A centrifugal separator according to claim 12, characterized in that the ratio between the radius of the circular arc and the inside diameter of the first pipe at a first end averted from the second pipe lies in the range of 0.1 to 0.3.

14. A centrifugal separator according to claim 12 or 13, characterized in that the opening angle of the circular arc lies in the range of 20 to 60 .

15. A centrifugal separator according to one of the daims 1 to 10, characterized in that the ratio between the inside diameter of the second pipe at the first end and the inside diameter of the first pipe at its first end lies in the range of 1.0 to 1.5.

16. A centrifugal separator according to one of the claims 1 to 10, characterized in that the opening angle of the circular arc decreases from the swirl generator hub to the inside wall of the first pipe.

17. A centrifugal separator according to one of the claims 12 to 16, characterized in that the radius of the circular arc increases from the swirl generator hub to the inside wail of the first pipe.