DE102011006066B4 - Water separator and method for separating water from a wet steam flow - Google Patents

Abstract

A water separator (10; 10a) for separating water from a wet steam flow, comprising - a first screen (12-1; 12a-1) having at least a first screen opening (14-1; 14a-1) and a second screen disposed downstream thereof (12-2; 12a-2) having at least a second screen opening (14-2; 14a-2) arranged at an offset from the first screen opening (14-1; 14a-1), and a water discharge device (16, 18) for discharging water incident on the second screen (12-2; 12a-2) adjacent the second screen opening (14-2; 14a-2).

Description

The present invention relates to a water separator and a method for separating water from a wet steam flow, for example a wet steam flow occurring in the region of a steam turbine plant. Furthermore, the invention relates to the use of such a water separator in a steam turbine.

The use of a water separator in a water-steam cycle of a steam turbine plant is for example from the EP 0 848 208 B1 known. In this known application example, the water separator is used for separating water (including impurities dissolved therein) from a wet steam flow between an evaporator and a superheater of the water-steam cycle. The known water separator is formed as a "separator bottle" of cylindrical shape provided with two tangential vapor inlet openings arranged at a shallow angle to the horizontal to produce a downward swirling flow of the incoming wet steam in the separator bottle. The separator thus operates on the principle of a "centrifugal separator".

The operating principle of the known water separator conditionally. special space requirements, for example with regard to its cylindrical shape design and the only within narrow limits variable design and arrangement of steam inlet and steam outlet openings. These particular space requirements may be a disadvantage in certain application environments.

Similar water separators are from the DE 1 912 805 A , of the US 2,857,980 A and the US 4,624,111 A known.

In the DE 1 912 805 A a helical flow is imposed on a vapor flow by means of a swirl paddle wheel and a backdriven wheel in the region of a swirl tube. At the downstream end of this arrangement, an annular gap is provided through which the steam in the water is discharged together with a portion of the steam into a chamber.

In the US 2,857,980 A For the separation of water from a steam flow, a rotating swirl flow is likewise used, through which a water film is formed on an annular sieve plate and water is withdrawn through openings in the sieve plate from the steam flow into a water collection chamber.

In the US 4,624,111 A a radially non-uniform water distribution is generated in a vapor flow in a pipe by means of special internals, in order to separate water in the vicinity of the pipe wall via an annular gap.

It is an object of the present invention to provide a novel type of water separator or a novel method for separating water from a wet steam flow.

• – ein erstes Sieb mit wenigstens einer ersten Sieböffnung und ein in Strömungsrichtung dahinter angeordnetes zweites Sieb mit wenigstens einer zweiten Sieböffnung, die mit einem Versatz zur ersten Sieböffnung angeordnet ist, und
• – eine Wasserabfuhreinrichtung zum Abführen von Wasser, welches benachbart der zweiten Sieböffnung auf das zweite Sieb auftrifft.

The water separator according to the invention comprises:

• A first sieve with at least one first sieve opening and a second sieve arranged behind it in the flow direction with at least one second sieve opening, which is arranged with an offset to the first sieve opening, and
• - A water discharge device for discharging water, which impinges on the second screen adjacent to the second screen opening.

The term "sieve" is used here in a very broad or figurative sense. As will be explained below, the screen is not used in a conventional manner, but has one or (as is common in conventional screens) multiple openings (screen openings). A "screen surface" consists of one or more screen openings and the area adjacent the screen opening or the areas between the plurality of screen openings.

Hereinafter, the water separator, its operation and various embodiments are first explained for the (very simple) case in which the separator has only a "first sieve opening" (of the first sieve) and only a "second sieve opening" (of the second sieve). However, it should already be noted at this point that the first sieve and / or the second sieve can each be provided with a plurality of first and second sieve openings. It will also be explained below that the sieve arrangement provided in the water separator according to the invention can comprise more than two sieves.

The functioning of the sieve arrangement according to the invention comprising a first sieve and a second sieve (and optionally further sieving) differs considerably from the conventional mode of operation of an arrangement of two (or more) sieves arranged one behind the other:
The conventional operation of a single screen is to trap those particles which, due to their dimensions, do not pass through the screen openings as they pass through the screen. Such an operation fails in the present application ("sifting out of water droplets") in that first, the water droplets in the steam flow due to their shape variability would simply "squeezed" through the screen openings and, secondly, that the screen openings would have to be very small to provide some water droplet retention function, which would disadvantageously result in very high flow resistance.

In contrast, the function of the vapor sieve assembly according to the invention, which consists of at least two sieves with mutually offset sieve openings, is based on the fact that the vapor is subjected to a flow deflection after flowing through the first vapor opening of the first (upstream) sieve in order to the transversely arranged second sieve opening of the second (downstream) sieve to arrive. Decisive here is that in this curved course of the vapor flow between the two sieves, the water droplets contained in the steam due to their inertia tend to flow through a less curved flow path and thus in a region of the second sieve adjacent to (or at a distance to) the second sieve opening (or in a region between second screen openings) impinge. However, these areas (eg, massive screen surfaces) may be provided with suitable drain structures to remove the impacted water droplets, thus avoiding their vapor flow driven entrainment to the screen openings of the second screen.

Of course, the water separator according to the invention also requires a certain amount of space. In contrast to the known "separation bottles", however, more advantageous designs can be selected for many applications. In particular, according to the invention, a water separator can advantageously be designed such that the directions of the steam inlet (at the first screen openings) and the steam outlet (eg at the second screen openings) are identical, wherein advantageously a very short construction length of the water separator is possible , In the simplest case, this length is defined by the sum of the "screen thicknesses" of the first and second screens plus the "screen spacing" between the two screens. If the sieve arrangement also has a third sieve (and possibly also a fourth sieve, etc.), the overall length of the water separator increases accordingly.

A further advantage of the water separator or active principle according to the invention is the "scalability" of the construction to a predetermined cross-sectional area of the relevant wet steam flow. Since each sieve used can have one or more sieve openings and the arrangement of several sieve openings on each sieve can be largely arbitrary, the construction according to the invention can be adapted in a simple manner to any cross-sectional areas and cross-sectional shapes of the relevant wet steam flow.

In one embodiment, the water discharge device comprises at least one water drainage channel extending in the interior of the second wire and at least one opening in this water drainage channel at a baffle surface of the second wire adjacent to the second wire opening.

In a further development, the water discharge device further comprises means for actively discharging water located in the water drainage channel (eg by using a "suction" by means of a water pump).

The first sieve can be used, for example, as a sieve plate, e.g. B. flat screen plate, be formed. At the first sieve, no components of the water discharge device are required, so that the first sieve can advantageously be provided with a very small thickness. In a particularly simple embodiment, it is a metal plate (eg of steel) which is provided with a first sieve opening or with a plurality of first sieve openings. A plurality of first screen openings is preferably provided in a regular arrangement on a one-dimensional or two-dimensional grid (in a mathematical sense).

The second sieve (and possibly further sieves) can also be designed as a sieve plate (eg made of metal, with one or more second sieve openings). As a component of the water drainage device, at least one water drainage channel can be formed inside this filter plate.

If the second sieve is provided with a plurality of second sieve openings, which are also preferably arranged according to a regular arrangement on a (mathematical) grid, then said water drainage channel in the second sieve can constitute a water collection channel which is used for merging and jointly discharging water which passes into the water drainage channel via several branches, whereby these branches are supplied via corresponding junctions at the areas between the second screen openings with water fractions (separated from the wet steam flow).

In one embodiment, the water separator further comprises a third sieve downstream of the second sieve and having at least one third sieve opening offset from the second sieve opening, the water discharge device further discharging water adjacent the third sieve opening to the third Sieve impinges, is formed.

As already mentioned, the water separator can also comprise more than three sieves arranged one behind the other. To form the water removal device, the second, third, etc. sieve each with suitable water drainage channels in the interior of this z. B. can be provided as a flat screen plates form-shaped screens over which the impacted water can be dissipated. In the very first, ie the furthest upstream screen such a drain construction is unnecessary. Rather, it is essential that the second sieve in the direction of flow and, if appropriate, further sieves following in the steam sieve arrangement are each equipped with a suitable drain construction and each sieve opening of a "subsequent sieve" is arranged with an offset to the or each of the sieve openings of the "preceding sieve" is.

With regard to the arrangement of a plurality of sieve opening in respective sieves is to be noted that these Sieböffnungsanordnungen z. B. may be provided identically for a first sieve and a third sieve. Likewise, the Sieböffnungsanordnungen a second screen and a fourth screen may be provided identically, according to the principle of the invention, the screen openings of the second screen with an offset with respect to the screen openings of the first screen and the screen openings of the third screen with an offset with respect to the screen openings of the second screen provided are. It is essential that in each space between two immediately adjacent screens, a curved flow of vapor is forced (to allow collection and removal of water droplets at the respective downstream screen).

• – Führen der Nassdampfströmung durch ein erstes Sieb mit wenigstens einer ersten Sieböffnung und ein in Strömungsrichtung dahinter angeordnetes zweites Sieb mit wenigstens einer zweiten Sieböffnung, die mit einem Versatz zur ersten Sieböffnung angeordnet ist, und
• – Abführen von Wasser, welches benachbart der zweiten Sieböffnung auf das zweite Sieb auftrifft.

The method according to the invention for separating water from a wet steam flow comprises the steps:

• Passing the wet steam flow through a first sieve having at least one first sieve opening and a second sieve arranged behind it in the flow direction with at least one second sieve opening which is arranged with an offset to the first sieve opening, and
• - discharging water, which impinges on the second sieve adjacent to the second sieve opening.

According to a particularly interesting embodiment of this method or use of the water separator according to the invention, a separation of water from a wet steam flow is provided, which occurs within a turbine housing of a steam turbine.

A steam turbine of the type of interest here may include a turbine housing having a turbine shaft rotatably mounted therein about a turbine axis, along the turbine shaft having a plurality of steam-flow stage groups each formed of a shaft-fixed blade structure and a stationary stator vane structure cooperating therewith in that a pressure and temperature-reducing expansion of the water vapor takes place in each of the step groups through which water vapor flows successively.

Such steam turbines are known from the prior art and can be used for example in nuclear power, geothermal, solar thermal, biomass or other power plants advantageous for the production of electrical energy.

Only by way of example on the DE 197 01 020 A1 referenced in which a steam turbine of the generic type is described. This known steam turbine comprises a turbine housing with a turbine shaft ("turbine runner") rotatably mounted therein around a turbine axis, wherein a plurality of steam-flow stage groups are provided along the turbine shaft each formed of a shaft-fixed blade structure and a housing-fixed vane structure meshing therewith. In turbine operation, a pressure and temperature-reducing expansion of the water vapor takes place in the successively flowed through by steam vapor stage groups to use energy from the water vapor for rotary drive of the turbine shaft.

To achieve a high efficiency of the energy conversion, it is known to be advantageous if a very extensive expansion of the water vapor takes place in the turbine, in which there is the greatest possible temperature difference between supplied and discharged water vapor. When falling below the tau line (or saturated steam curve), condensation of water in the steam flow path still occurs within the turbine housing. The result is blade erosion (eg so-called "droplet impact erosion") and erosion corrosion, in particular in turbine regions further downstream in the course of the flow, eg, B. in "low pressure areas".

At the time of the DE 197 01 020 A1 known steam turbine this problem is solved by a so-called "reheating". In this case, at least one point in the steam flow already partially expanded water vapor is not released directly to a subsequent stage group, but first passed away from the turbine to a separately installed steam turbine heater to be returned to the turbine after suitable heating back.

This known from the prior art solution with at least one operated outside the turbine steamer requires a high investment outlay and an additional energy input (eg., Fuel energy).

There is therefore a need for a steam turbine of the type described above to reduce the problems associated with condensing out water in the steam flow profile in order to be able to dispense in this way, in particular, with costly reheating.

According to the present invention, therefore, an embodiment of the steam turbine is proposed in which at least one of the stage groups for discharging wet steam is designed with a water content of more than 5%, wherein in the steam flow path behind this stage group a water separator of the type already described above is arranged over in which the water vapor after reduction of the water content to less than 3%, in particular less than 2%, is delivered to a subsequent of the step groups.

In such a steam turbine, at least one of the stage groups is designed to dispense wet steam having a water content of more than 5%, preferably in the range of 5 to 15%. The relevant stage group thus advantageously allows a high efficiency of energy conversion. To avoid the problems otherwise to be expected, a water separator is arranged in the steam flow path behind this step group, via which the water vapor is discharged to a subsequent one of the step groups after reduction of the water content to less than 3%, preferably less than 2%, or even about 0% ,

The steam turbine according to the invention can be used in particular for generating electrical energy by means of an electric generator driven therefrom.

One in the steam flow first stage group, for example, as part of a "high-pressure stage" of the steam turbine or a turbine containing this steam turbine plant, live steam with a pressure of z. B. more than 100 bar and a temperature of z. B. more than 400 ° C are supplied. At the end of the last stage group in the steam flow pattern, the expanded steam can reach a pressure of, for. B. less than 1 bar (ie vacuum) and a temperature of z. B. less than 50 ° C.

In an advantageous embodiment of the turbine, no intermediate superheating in the steam flow path is provided in order to avoid the associated plant-related expenditure.

The steam turbine may comprise two, three, four or even more stage groups, it being possible for at least one water separator with the function explained above to be arranged behind one or more stage groups in the steam flow profile.

In a preferred embodiment, the water separator is housed completely within the turbine housing.

The (at least one) water separator in this case has a "steam sieve arrangement" of the type already described above for trapping water droplets. The vapor sieve assembly, preferably housed within the turbine housing, may be radially sealed from the turbine housing and / or from the turbine shaft to avoid a flow of wet steam past the vapor sifter assembly during turbine operation.

In another embodiment, the water separator is partially disposed outside of the turbine housing. In this case, however, all parts of the water separator located outside of the turbine housing are preferably structurally combined with the turbine housing, ie, for example. B. housed in flanged, welded or integrally molded as housing casings with the housing body piping or formed from such piping. All parts of the Wassersepartors are preferably housed within a (imaginary) cylindrical space whose axial length corresponds to the axial extent of the turbine shaft within the turbine housing and whose radial diameter is smaller than 4 times, preferably smaller than 3 times, the maximum diameter a turbine housing body (turbine housing without Wassersepartorkomponenten).

In the partial embodiment of the water separator outside the turbine housing the Dampfsiebanordnung can be installed outside of the turbine housing and connected to at least one steam supply line and at least one vapor return line to the interior of the turbine housing.

In any event, the steam sieve assembly comprises a plurality of sieves (one behind the other) with the sieve opening (s) of each sieve being offset from the sieve opening (s) of a sieve immediately upstream in the steam sieve assembly.

According to one embodiment it is provided that water separated from the wet steam leads out of the turbine and others Place a water-steam cycle is fed back. In this cycle, in the known manner, in the steam flow path at the end of the turbine led out exhaust steam z. B. first to a condenser and from there on to a steamer to be supplied by the steamer heater with high pressure and high temperature provided live steam, especially at the beginning of the steam flow curve of the turbine (at a "live steam").

In a preferred embodiment, a plurality of water separators of the said function are provided, each of which is arranged between two steam groups in the steam flow course of the successive stages groups.

The invention will be further described by means of embodiments with reference to the accompanying drawings. They show:

1 a sectional view of a water separator according to the invention to illustrate the operation,

2 a sectional view of a water separator according to another embodiment, and

3 a sectional view for illustrating an embodiment of a steam turbine according to the invention.

1 illustrates a water separator 10 for separating water from a wet steam flow, as may occur, for example, in the region of a water-steam cycle of a steam turbine plant.

The term "wet steam" denotes in the usual way a mixture of water vapor (in the gaseous phase) and water (in the liquid phase).

The flow through the water separator 10 takes place in 1 from left to right (flow direction). Flow paths of the vapor are symbolized by arrows, the dashed arrows symbolizing the flow paths of the water vapor portion and the solid arrows symbolizing the flow paths of the water portion (condensate in the form of water droplets).

The water separator 10 includes a first sieve 12-1 with a first sieve opening 14-1 and a downstream in the flow direction at a distance d arranged second sieve 12-2 with a second screen opening 14-2 with an offset a to the first sieve opening 14-1 is arranged. As it is in the left part of 1 is shown, occurs at the first screen opening 14-1 initially wet steam containing a "dry" vapor content and a water content (condensate) in the screen assembly of the water separator 10 one. Behind this sieve opening 14-1 of the first sieve 12-1 there is a deflection of the vapor flow in the transverse direction (with a component orthogonal to the flow direction), since the second sieve opening 14-2 of the subsequent second screen 12-2 with the offset a with respect to the sieve opening 14-1 of the first sieve 12-1 is arranged.

In this flow guide, the water droplets forming the water portion of the acceleration or deflection of the steam flow in the space between the sieves 12-1 and 12-2 not or not to the extent that the dry vapor content is deflected. The velocity vectors of steam and water droplets differ in magnitude and direction.

While the vapor portion (dashed arrows) the openings 14-1 and 14-2 Flows through "easily", meets a significant proportion of water droplets (solid arrows) on an acting as a baffle surface portion of the second screen 12-2 and will be there at a junction 16 caught in a water drainage channel 18 leads.

The adjacent to the sieve opening 14-2 planned junction 16 forms together with the water drainage channel 18 a water drainage means for removing water adjacent to the sieve opening 14-2 on the second sieve 12-2 hits, so to speak, the opening 14-2 "Misses".

In 1 symbolizes the length of the drawn arrows the amount of velocity vectors. It can be seen that the water droplets (solid arrows) tend to be more straightforward and at a rather constant speed through the sieve opening 14-1 flow through and continue on the baffle or the junction 16 of the following screen 12-2 whereas the speed of the vapor fraction is in the area of the sieve openings 14-1 and 14-2 each accelerated and behind these screen openings each slowed down a bit.

The equipment of the baffle of the second sieve 12-2 with the described drain construction 16 . 18 avoids entrainment of the water impacted on the baffle through the second screen opening 14-2 ,

In one embodiment, it is provided that the screen openings are respectively elongated, namely orthogonal to the flow direction and orthogonal to the "deflection direction" (The deflection direction is z. in 1 vertical). This design of the screen openings is z. B. in particular for in 1 illustrated case, in which the first sieve 12-1 and the second sieve 12-2 in each case only a single sieve opening 14-1 respectively. 14-2 exhibit. However, such an elongate shape can also be provided for the case of several screen openings of the first and / or second screen.

In the following description of further embodiments, the same reference numerals are used for equivalent components, each supplemented by a small letter to distinguish the embodiment. In this case, essentially only the differences from the embodiment (s) already described are discussed and, moreover, reference is hereby explicitly made to the description of previous exemplary embodiments.

2 is a schematic sectional view of a Dampfsiebanordnung a water separator 10a , in the example shown, of three screen plates arranged one behind the other 12a-1 . 12a-2 and 12a-3 is formed.

With this arrangement, the above with respect to 1 already described method for separating water from a wet steam flow to a certain extent twice in succession, namely first by means of the screen plates 12a-1 and 12a-2 , and then again by means of the sieve plates 12a-2 and 12a-3 ,

Another difference to the simple arrangement according to 1 is that each of the sieve plates 12a-1 to 12a-3 with a regular arrangement of a plurality of screen openings 14a-1 . 14a-2 respectively. 14a-3 is provided.

In one embodiment, it is provided that the screen openings 14a-1 . 14a-2 respectively. 14a-3 are elongated orthogonal to the flow direction and orthogonal to the "deflection direction", in particular in the arrangement of the screen openings 14a-1 . 14a-2 respectively. 14a-3 on a respective one-dimensional (mathematical) grid. Deviating from this, the sieve openings 14a-1 . 14a-2 respectively. 14a-3 however, for example B. also have an at least approximately circular shape, in particular in the arrangement of the screen openings 14a-1 . 14a-2 respectively. 14a-3 on a respective two-dimensional (mathematical) grid.

The flow through the water separator 14a takes place in the figure again from left to right. At the screen openings 14a-1 Wet steam containing a portion of water vapor (dashed arrows) and a proportion of water (solid arrows). Behind these screen openings 14a-1 the first screen plate 12a-1 there is a deflection of the steam flow in several different transverse directions (each with a component orthogonal to the flow direction), towards the screen openings 14a-2 the following (second) screen plate 12a-2 , Every sieve opening 14a-2 the second screen plate 12a-2 is with an offset to the screen openings 14a-1 the first screen plate 12a-1 arranged to force the mentioned deflection (here: splitting of the flow in several transverse directions).

For the sake of simplicity of illustration, is in 2 the drainage structure of the second screen plate 12a-2 (and the third screen plate 12a-3 ) not shown. Such a device for removing water, which in areas between the second screen openings 14a-2 (or in areas between the screen openings 14a-3 the third screen plate 12a-3 ) could, for example, be formed as already described with reference to FIG 1 has been described. Corresponding drainage structures (such as the mentioned water drainage channel) are in the example according to 2 both in the second screen plate 12a-2 as well as in the driette screen plate 12a-3 provided.

In a preferred embodiment, the screen plates are at the respective baffles 12a-2 and 12a-3 , ie in areas between the screen openings 14a-2 and in areas between the screen openings 14a-3 , Junctions provided at those points where the water preferably impinges. This impinging water can pass through these junctions in one or more drainage channels, which are inside the sieve plates 12a-2 and 12a-3 are formed.

Through these channels a certain "suction" can be realized by a difference of those pressures that prevail on the one hand at the junctions and on the other hand at the outputs of the channels. The channels can be on the output side z. B. in a common water collection channel, which in turn is connected to the input of a water pump to "suck off" the trapped water "active" or deduce.

Hereinafter, with reference to 3 an example of an advantageous use of a steam separator of the types described above explained.

3 shows a steam turbine 30b comprising an approximately cylindrical turbine housing 32b with one rotatable about a turbine axis 34b stored turbine shaft 36b ,

Along the turbine shaft 36b are several stages of steam flow through by steam 38b-1 . 38b-2 . 38b 3- and 38b-4 provided in the illustrated embodiment in the figure to be flowed through successively from left to right.

At a live steam inlet (not shown), live steam at high pressure and high temperature is introduced into the turbine 30b introduced and after the flow through the stage groups 38b-1 to 38b-4 at low pressure and low temperature via a steam outlet (not shown) back out of the turbine 30b led out. In a manner known per se, this exhaust steam can then be recycled via a condenser and a steam generator as live steam for the turbine 30b be used.

Each of the step groups 38b-1 to 38b-4 is from a rotationally fixed with the turbine shaft 36b connected blade structure and a cooperating and stationary to the turbine housing 32b formed Leitschaufelstruktur formed.

Typically, a blade structure in this case consists of a series of axially spaced blade rings with radially from the turbine shaft 36b protruding blades 40b and a vane structure consists of a series of axially spaced apart vane rings with a plurality of stator vanes radially inwardly projecting from stationary vane carriers 42b , so that in the steam flow path of a step group alternately blades and vanes are flowed around by water vapor.

In the successively flowed through by water vapor stage groups 38b-1 to 38b-4 takes place in each case a pressure and temperature-reducing expansion of the water vapor.

A special feature of the steam turbine 30b is that the step groups 38b-1 . 38b-2 and 38b-3 for dispensing wet steam having a water content of, for example, about 5 to 15% (and accordingly a water vapor content of about 85 to 95%) are designed, wherein in the respective further steam flow course behind these stage groups 38b-1 . 38b-2 . 38b-3 one water separator each 10b-1 . 10b-2 respectively. 10b-3 is arranged, by means of which the wet steam at these points each (liquid) water is withdrawn. By means of the respective water separator, the steam is thus mixed with a reduced proportion of water (and correspondingly increased water vapor content) to the steam flow in each case following (in 38b-2 . 38b-3 and 38b-4 ) of the step groups 38b-1 to 38b-4 issued.

In the illustrated embodiment, the steam turbine 30b designed and operated such that the water content of the upstream of each of the water separators 10b-1 . 10b-2 respectively. 10b-3 The wet steam of about 10% after passing through this water separator on the downstream side is reduced to a much smaller value. Preferably, a reduction by at least a factor of 3, more preferably by at least a factor of 5. In an extreme case, the proportion of water is practically reduced to 0%, so "dry steam" generated.

Each of the water separators 10b-1 to 10b-3 According to the illustrated embodiment, the water vapor dries more or less, so that downstream of it especially the energetically high-quality water vapor for further expansion in the turbine 30b is continued.

That of the water separators 10b-1 to 10b-3 withdrawn water can, for example, from the turbine 30b led out and recycled (not shown), about to reuse this in the water-steam cycle of a power plant concerned.

Advantageously, the illustrated construction allows the turbine 30b a waiver of complex external devices for so-called reheating, as used in the prior art to avoid too high a water content, especially in low-pressure side turbine areas. If in the illustrated turbine 30b Nevertheless, a reheat is provided, so the facilities used for this purpose can be advantageously designed less expensive.

It is understood that the concrete number and arrangement or Durchströmungsreihenfolge the stage groups 38b-1 to 38b-4 and the water separators 10b-1 to 10b-3 are merely exemplary and can be modified. Optionally, depending on the design of the individual stage groups, thus z. B. water separators may also be arranged only behind some or those groups of steps in which a release of wet steam is to be expected. This is usually the case in conventional turbine designs only in so-called medium-pressure stages and especially low-pressure stages, or in so-called "saturated steam processes".

In some steam turbine designs, such stages are often structurally separated from one another and connected to one another via steam lines. In this case, the example in 3 shown steam turbine 30b Accordingly, only represent such a medium-pressure level or low-pressure stage (an overall larger steam turbine plant).

The water separators 10b-1 to 10b-3 are completely within the turbine housing in the example shown 32b accommodated. In this case, only water discharge lines through the turbine housing 32b passed out (not shown). Each of the water separators 10b-1 to 10b-3 includes a vapor sieve assembly for trapping water droplets from the vapor stream, for example, as above with respect to FIG 1 and 2 already described.

In order to avoid a steam flow "past the water separators", these are in the radial direction on the one hand opposite the turbine housing 32b and, on the other hand, opposite the turbine shaft 36b sealed.

In summary, with the steam turbine 30b Advantageously realized an "internal Dampfnässeseparation", by means of which, in particular when using lower live steam pressures and temperatures inadmissible high Abdampffeuchten in the expansion, and as a result blade erosion and similar problems can be avoided. Any protective measures on the turbine components, such. As hardening of the blades or heating of the vanes, are unnecessary or can be provided with less effort.

For the water separators may differ from the embodiment according to 3 Also, a partial arrangement of components of these water separators are selected outside of an actual turbine housing.

For example, a water separator can be connected to the turbine housing via a relatively short pipe arrangement (principle: pipe removal).

Also, a water separator may be coupled to the turbine housing via a conduit connection formed by a housing casting (eg, "bleed port").

Alternatively to the installation of the water separator within the steam-flowed interior of the turbine housing (see. 3 ) is therefore also an installation on flanged or welded pipes or in housing attachments or integrally connected to the turbine housing facilities possible.

When using one or more water separators in a steam turbine of the above-described and exemplified in 3 The kind of water that has been trapped can be taken out of the respective turbine housing and z. B. be supplied again elsewhere in the water-steam cycle.

Claims (9)

Water separator ( 10 ; 10a ) for separating water from a wet steam flow, comprising - a first sieve ( 12-1 ; 12a-1 ) with at least one first sieve opening ( 14-1 ; 14a-1 ) and a downstream in the flow direction arranged second sieve ( 12-2 ; 12a-2 ) with at least one second screen opening ( 14-2 ; 14a-2 ) with an offset to the first sieve opening ( 14-1 ; 14a-1 ), and - a water discharge device ( 16 . 18 ) for removing water, which adjacent to the second sieve opening ( 14-2 ; 14a-2 ) on the second sieve ( 12-2 ; 12a-2 ). Water separator ( 10 ; 10a ) according to claim 1, wherein the water discharge device ( 16 . 18 ) at least one inside the second screen ( 12-2 ; 12a-2 ) running water drainage channel ( 18 ) and at least one junction ( 16 ) in this water drainage channel ( 18 ) on a baffle surface of the second screen ( 12-2 ; 12a-2 ) adjacent to the second screen opening ( 14-2 ; 14a-2 ). Water separator ( 10 ; 10a ) according to claim 2, wherein the water discharge device ( 16 . 18 ) further means for actively discharging in the water drainage channel ( 18 ) water. Water separator ( 10 ; 10a ) according to one of the preceding claims, wherein the second sieve ( 12-2 ; 12a-2 ) as a screen plate with at least one running inside the screen plate water drainage channel ( 18 ) is trained. Water separator ( 10a ) according to one of the preceding claims, further comprising a flow direction behind the second sieve ( 12a-2 ) arranged third sieve ( 12a-3 ) with at least one third sieve opening ( 14a-3 ) with an offset to the second sieve opening ( 14a-2 ), wherein the water discharge device further for discharging water, which adjacent to the third sieve opening ( 14a-3 ) on the third sieve ( 12a-3 ), is formed. A method for separating water from a wet steam flow, comprising - passing the wet steam flow through a first screen ( 12-1 ; 12a-1 ) with at least one first sieve opening ( 14-1 ; 14a-1 ) and a downstream in the flow direction arranged second sieve ( 12-2 ; 12a-2 ) with at least one second screen opening ( 14-2 ; 14a-2 ) with an offset to the first sieve opening ( 14-1 ; 14a-1 ), and - discharging water adjacent to the second screen opening ( 14-1 ; 14a-1 ) on the second sieve ( 12-2 ; 12a-2 ). Use of a water separator ( 10b-1 to 10b-3 ) according to one of claims 1 to 5 and / or a method according to claim 6 for separating water from a wet steam flow, which within a turbine housing ( 32b ) of a steam turbine ( 30b ) occurs. Steam turbine ( 30b ), comprising a turbine housing ( 32b ) with a rotatable about a turbine axis ( 34b ) stored turbine shaft ( 36b ), whereby along the turbine shaft ( 36b ) a plurality of steam flow-through stage groups ( 38b-1 to 38b-4 ), each consisting of a shaft-fixed blade structure ( 40b ) and a cooperating housing-fixed vane structure ( 42b ) are formed, so that in each of the succession of steam flow-through stage groups, a pressure and temperature- reducing expansion of the steam takes place, characterized in that at least one ( 38b-1 to 38b-3 ) of the stage groups ( 38b-1 to 38b-4 ) is designed for the delivery of wet steam with a water content of more than 5%, wherein in the steam flow path behind this stage group ( 38b-1 to 38b-3 ) a water separator ( 10b-1 to 10b-3 ) according to any one of claims 1 to 5, above which the vapor after reduction of the water content to less than 3%, in particular less than 2%, to a subsequent ( 38b-2 to 38b-4 ) of the stage groups ( 38b-1 to 38b-4 ) is delivered. Steam turbine ( 30b ) according to claim 8, wherein the water separator ( 10b-1 to 10b-3 ) completely within the turbine housing ( 32b ) is housed.

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