Title of Invention

STEAM TURBINE PLANT, AND METHOD OF OPERATING A STEAM TURBINE PLANT

Abstract

A steam turbine plant (2) having a vacuum pumping arrangement (14) which has a jet pump (26) and a liquid ring pump (28) arranged in series one after the other, characterized in that a steam One (48) connected to a seating-steam circuit (50) for a turbine seal (52) and Mended for feeding steam (D), collecting in the plant (2), as motive fluid (T) for the jet pump (26) is connected to the jet pump (26).

Full Text

Description Steam turbine plant, and method of operating a steam turbine plant The invention relates to a steam turbine plant having a vacuum pumping arrangement which has a jet pump and a liquid ring pump arranged in series one after the other. The invention also relates to a method of operating a steam turbine plant, in which a plant component is deaerated by means of a vacuum pumping arrangement which has a jet pump and a liquid ring pump arranged in series one after the other. In a steam turbine plant, for example in the field of power generation, a main turbine plant having a plurality of turbine stages is provided as a rule in order to utilize as effectively as possible the energy content of the steam provided. As a rule, high-capacity steam turbine plants have a high-pressure stage, an intermediate-pressure stage and a low-pressure stage, steam heated in a boiler being fed to the , high-pressure stage and expanding in the direction of the low-pressure stage. At the end, the low-pressure stage has a vacuum in the order of magnitude of between 80 mbar and 18 mbar. The steam discharging from the low-pressure stage is fed to a condenser and is condensed there. The gas quantity collecting during the condensing in the condenser must be drawn off from the latter. Provided for this purpose is a vacuum pumping arrangement, which, on account of the low final pressure at the low-pressure stage, must reach a vacuum of, for example, turbine plant and which is large as a rule, the vacuum pumping arrangement must be designed for drawing off a large gas quantity of a delivery gas from the condenser in order to deaerate the latter. Furthermore, in a steam turbine plant for a large power plant, an auxiliary turbine for a feedwater supply to the boiler is normally provided, this auxiliary turbine having, for example, an output of 20 MW, compared with an output of the main turbine plant of about 1 GW. A condenser, which must be deaerated, is likewise assigned to this auxiliary turbine. As a rule, the respective condenser comprises a tube system, to which the steam to be condensed is admitted from the turbine. The steam is cooled by means of water, which is fed to the condenser via a "water chamber". In order to maintain the operability of the condenser, the water chamber must also be deaerated. On account of the different requirements for the ,deaerating capacity with regard to the condenser for the low-pressure stage, for the auxiliary turbine, and with regard to the water chamber of the condenser, a separate vacuum pumping arrangement is currently provided for each of these three subsystems. For deaerating a condenser of a steam turbine, GB 1 542 483 has disclosed a vacuum pumping arrangement in which a jet pump and a liquid ring pump are provided in series one after the other. The motive fluid provided for the jet pump is air. The vacuum to be achieved is improved by connecting the jet pump upstream of the liquid ring pump. A vacuum of about 50 mbar can typically be achieved with a liquid ring pump. A vacuum of up to In the system consisting of the jet pump and the liquid ring pump there is generally the problem that the liquid ring pump has to be designed for both the quantity of the actual delivery gas to be drawn off plus the quantity of the motive fluid for the jet pump- In this case, the 3 requisite quantity of motive eir for on eir-opereted Jet pump to many times higher then the quantity of delivery gos to be drawn off from the consender. For example, in order to compress a delivery-gos mass flow from a condenser, consisting of a mixture of about 15 kg/h of eir end 35 kg/h of steam, from about 40 mbar to 125 mbar by means of the jot pump, e working-air mass flow of about 200 ktg/h is required. On account of the very high eir proportion, the liquid ring pump is to be designod for dry eir as delivery gas. This reduces the cepactiy of the liquid ring pump, compered with most air so delivary. A liquid ring pump and its operating principle can be seen, for example, from the Siemens brochure "ELMO-L28L1 -luftgekuhit, offrel: die neue Generation von Vakuumpumpen" [ELMO-L2BL1 - air-cooled, oil-free: the new generation of vacuum pumps], Siemens Aktilengeselschaft Germany, 12/98, Order No.: E20001-P7d2-A20d, or from the Internet ct http:\\www.ad.aiemens.de/eimo (status August 2000). The liquid ring pump described has on impeller cliting ecccntricelly in a housing. By the impellor rotetion, on operating medium, as a rule water, forms a water ring revolving with the impellerer in the housing. On account of the eccentric arrangement of the impeller, sectiorml space of different size form between the impeller hub end the water ring revolning with the Impeller, and the medium to be pumped is compressed in these sectiond spaces. Furthermore, tho combination of o jot pump wtth downstream liquid ring pump has been disclosed, for example, by EP 0 88 226 A2, US 4,484,457 A end DE 2913860A1. 4 Aocording to 6P 008 226, the liqued ring pump is operated with oil as operating medium, which is heated up to a temperature of about 130°C. in order to utilize the energy stared in the off, provision is mede to eveporato water via e heat exchanger end to feed this steam as motive fluid to the Jet pump. A separate supply of motive fluid is therefore not neocessery in this system. However, this system is restricted to oil-operated liquid ring pumps, in which the oil can be heated to temperatures above 100oC. As a rule, the liquid ring pumps are operated with water, which b normally heated up to about 35°C at most, as con be seen from the abovemontioned Siemens brochure. According to DE 20 13 980 A1, air is fed as motive fluid to the jot pump from a separator assigned to the liquid ring pump. In the case, the air extrocted from the separator is dehydrated so that air which is as dry as posseble is fed to the Jet pump. The object of the invention to to permit cost-effective operation of a steam turbine plent in a simple instellation. The object is achieved according to the invention by a steam turbine plant having a vacuum pumping arrangement which has a jet pump ami a liquid ring pump arranged in series one after the other, a steam line for feeding steam, collecting in the plant, as motive fluid for the jet pump being connected to the jet pump. The steam used in this case is in particular excess steam in order not to Impair the efficiency of the steam turbine plant The use of steam as motive fluid has tho decicive advantage that, es a , the quantity of noncondensable motive fluid required is markedly reduced compered with tho motive air normally used. 5 As a result, It is possible to design the liquid ring pump arranged downstream of the Jet pump for markedly smeller mass flows, so that the mass flow to be delivered by the liquid ring pump descreses by about 40 - 90%, since the vaporous mass proportion in the liquid ring pump condenses and does not have te be compressed to atmospheric pressure. The steam line via which steam is fed as motive fluid to the jet pump is expodiently connocted to a selecting-steam circult for a turbine-cheft selecting system. To seal the rotottng turtrine shaft, a fcbyrtnth seal, ttvough which ^seaSng steam" Is drected, te provided as a rute. Alto teovSng ffie turbine seal, thb sea£nfl steam Is also referred to as low-ton=ion ctoam. Thb tow4©nsion steam to a Vcste producT coOecfinfl in tha ctoom turbto plant aid Is tharcforo eq^edaOy ouitcbte for use ta motive fluid under cfrnocphcrtc preccure wKhout bnptirtnci the effideftcy of the tteam tmbino plant In 6dcEtk>nt the feeding of the tow^encton ctecm to the vocuum pumping arrangement cteo has the decisive adventege that the tow-eendon steam - due to the principle of the iqufd ring pump - condenses. The condensing system, normally provided in a steam turbine ptont, tor the low-tenskm steam Is therefore not necessary. As a result, Investment costs can be saved, and in oddffon tho requite Instoflctkm requfremant to roducod corrq>erod wtth conventional ctoom tufWnepScnts. 6 A gas line for admixing air for forming a steam/air mixture as motive fluid for the jet pump is expediently connected to the steam line. This results in especially efficient operation for the jet pump. In particular, an approximately uniform mass flow distribution between air and steam is set for the mixture. In addition, the admixing of air has the advantage that the requisite quantity of motive fluid can be set in a simple manner, in particular when the quantity of low-tension steam is limited, so that this steam quantity alone is not sufficient as motive fluid. In this case, the gas line, with its further end, is expediently connected on the pressure side to the liquid ring pump and in particular to a separator assigned to the liquid ring pump. The air compressed to atmospheric pressure by the liquid ring pump is therefore also used as motive fluid. This has the advantage that a separate compressor for feeding the jet pump is -not required. According to an expedient configuration, the vacuum pumping arrangement is connected to a condenser via a first deaerating line for deaerating said condenser, which is provided for condensing process steam discharging from a steam turbine, in particular from a low-pressure part of a steam turbine. The vacuum pumping arrangement is at the same time preferably connected via a second deaerating line to a second condenser, which is assigned to an auxiliary turbine. Thus preferably both the condenser of the main turbine and that of the auxiliary turbine are deaerated via the same vacuum pumping arrangement. A plurality of vacuum pumping arrangements assigned to the individual condensers are therefore not necessary. 8 As a rule, the condenser, for a cooling liquid, has a water chamber, which, in order to deaerate it, is preferably connected to the vacuum pumping arrangement via a third deaerating line. A uniform, central vacuum pumping system in the form of the vacuum pumping arrangement is therefore provided, and this vacuum pumping system provides a vacuum for a multiplicity of components in the steam turbine plant. As a result, the installation cost and also the maintenance cost with regard to the vacuum pumping system are markedly reduced compared with a multiplicity of decentral vacuum pumping systems. To deaerate the water chamber, the third deaerating line is preferably connected to an additional port of the liquid ring pump. Via this additional port, saturated water-chamber air being emitted from the cooling water is drawn off from the water chamber. This has the essential advantage that the quantity of saturated air drawn off from the water chamber is fed separately to the liquid ring pump and is not added to the delivery-gas quantity drawn off from the two condensers. In this case, the additional port is expediently arranged between a suction connection and a pressure connection of the liquid ring pump and is connected to a working or compression space forming during operation. The third deaerating line therefore feeds the saturated air from the water chamber to the liquid ring pump in an intermediate region between the suction connection and the pressure connection. In this region, a sufficient vacuum for deaerating the water chamber is still provided by the liquid ring pump. At the same time, however, the feeding at this point does not lead to an increase, or only leads to an imperceptible increase, in the power requirement of the liquid ring pump. Delivery capacity is provided by the liquid ring pump via the cavitation protection port virtually "for nothing". When the third deaerating line is arranged at the additional port, the liquid ring pump therefore does not need to be of larger dimensions. The use of such an additional port as an additional suction connection is a basic principle here and is generally suitable for all liquid ring pumps and is not restricted to application in a steam turbine plant. A liquid ring pump having such an additional port is also suitable, for example, for deaerating a screen part on papermakinq machines in the paper industry. In general, such a liquid ring pump is suitable for use in the field of papermaking. By suitable placing of the additional port between the suction connection and the pressure connection, and by the selection of the diameter of the additional port, the suction capacity can at the same time be varied within certain limits both with regard to the volumetric quantity and with regard to the vacuum to be achieved. Furthermore, the object is achieved according to the invention by a method of operating a steam turbine plant, in which a plant component is deaerated by means of a vacuum pumping arrangement which has a jet pump and a liquid ring pump arranged in series one after the other, steam collecting in the steam turbine plant, in particular excess steam, being fed as motive fluid to the jet pump. The advantages and preferred configurations recited with regard to the steam turbine plant can accordingly be applied to the method. Advantageous configurations of the method are set down in the subclaims. 9 An exemplary embodiment of the invention is explained in more detail below with reference to the accompanying drawing,in which: Fig. l shows a schematic cutaway representation of a steam turbine plant, and Fig. 2 shows a schematic sectional view through a liquid ring pump. A steam turbine plant 2 according to fig. 1 has a steam turbine 4 which in particular is a low-pressure stage of a, for example, 3-staqe main turbine plant. Such a multistage main turbine plant is used, for example, in power plants for the generation of power with an output within the gigawatt range. On the output side, the steam turbine 4 has a vacuum, which in a low-pressure stage is typically within a range of between 80 mbar and 18 rnbar. Process steam P fed to the steam turbine 4 leaves the latter via output lines 6 and is fed to a first condenser 8. The process steam P is condensed in this condenser 8, the condensate being discharged via a discharge line 10 and fed again as feedwater to a boiler (not shown in any more detail). During the condensing, a gas/steam mixture designated as delivery gas F collects in the first condenser 8 and is drawn off via a first deaerating line 12 by a vacuum pumping arrangement 14. Furthermore, the steam turbine plant 2 has an auxiliary turbine 16 which is designed in a similar manner to the steam turbine 4 but for a markedly lower output. This auxiliary turbine 16 is used in particular for driving a feedwater pump and typically has an output of about 20 MW. In a similar manner to the steam turbine 4, a second condenser 18 is 10 assigned to the auxiliary turbine 16, the process steam P fed to the auxiliary turbine 16 being condensed in this second condenser 18. In a similar manner to the first condenser 8, the condensate is discharged via a discharge line 10. To deaerate the second condenser 18, a second deaerating line 20 is provided, which is likewise connected to the vacuum pumping arrangement 14. Via this second deaerating line 20, a gas/steam mixture is likewise pumped out of the second condenser 18 as delivery gas F. In this case, the first deaerating line 12 opens into the second deaerating line 20. The two condensers 8, 18 preferably have water as cooling medium, which is stored in a water chamber 22 of the respective condenser 8, 18. During operation of the condensers 8, 18, an air cushion forms in the respective water chamber 22. To deaerate at least the water chamber 22 of the first condenser 8, a third deaerating line 24 is provided, which likewise leads to the vacuum pumping arrangement 14. In this case, the saturated air being emitted from the cooling water is drawn off from the water chamber 22 and is designated as water-chamber air WL. The vacuum pumping arrangement 14 comprises a jet pump 26 and a liquid ring pump 28 arranged downstream of the jet pump 26 in the direction of flow. To this end, the second deaerating line 20 is connected to a suction region 27 of the jet pump 26, and the latter is connected on the output side to a suction connection 30 of the liquid ring pump 28. The delivery gas F from the two condensers 8, 18 is thus first of all precompressed by the jet pump 26. To this end, the jet pump 26 is operated with a motive fluid T which is fed externally and mixes with the delivery gas F. The pressure in the first condenser and in the second condenser 18 is typically within a range which corresponds approximately to the output pressure 11 of the steam turbine 4 and of the auxiliary turbine 16, respectively. There is therefore a vacuum within a range of between 80 and 18 mbar in both condensers 8, 18. Consequently the delivery gas F likewise has this vacuum. It is compressed approximately by the factor 3 in the jet pump 26 and then further up to ambient pressure in the liquid ring pump and is expelled via a pressure connection 34. Furthermore, the liquid ring pump 28, between the suction connection 30 and the pressure connection 34, has an additional port 35, to which the third deaerating line 24 is connected. In this case, the additional port 35 is arranged between an intake slot 70 and a pressure slot 72 (cf. fig. 2) in "control disks" (not shown here) of the liquid ring pump 28. Due to the operating principle of the liquid ring pump 28, the pump mixture of delivery gas F and motive fluid T fed via the suction connection 30 mixes with the operating medium of ., the liquid ring pump 20. In this case, the operating medium is water W. The latter together with condensate possibly collecting from the pump mixture is separated from air L in a separator 38. The water W is fed again to the liquid ring pump 28 via a heat exchanger 40. The air L is fed as motive fluid T to the jet pump 26 via a gas line 42, in which a valve 44 is connected. Excess air L is given off to the environment from the vacuum pumping arrangement 14 via an exhaust-air line 46. It is essential that, in addition to the air L, steam D is also fed as motive fluid T to the jet pump 26 via a steam line 48. A further valve 44 is connected in the steam line 48. In this case, the steam line 48 is connected to a sealing-steam circuit 50 in which sealing steam S is directed through a number of turbine seals 52. The turbine seals 52 in this case are assigned to the steam turbine 4 and to the auxiliary turbine 16 and are designed as labyrinth seals in order to 12 seal off a rotating shaft of the turbines 4, 16 from the environment. After flowing through the turbine seals 52, the sealing steam is also referred to as low-tension steam. This steam D is fed as motive fluid T to the jet pump 26. The motive fluid T is therefore a steam/air mixture, it being possible for the respective proportions of the steam D and of the air L to be set via the two valves 44. An equal distribution between steam D and air L is preferably set. If an adequate steam quantity is available, steam D may also be used exclusively as motive fluid T. Since the low-tension steam is excess steam collecting in the steam turbine plant 2, the overall efficiency of the steam turbine plant 2 is not impaired by use of the low-tension steam as motive fluid T. In addition to the use of the low-tension steam, other types of steam collecting in the steam turbine plant are also suitable. For example, the steam collecting in the sealing-steam system for control purposes and normally discarded in one of the condensers 8, 18 is suitable. The operating principle of a liquid ring pump 28, which has an impeller 64 mounted eccentrically in the housing 62 of the liquid ring pump 28, can be seen with reference to the schematic representation of a cross section through the liquid ring pump 28 according to fig. 2. During operation, the water W forms a liquid ring 66 which revolves with the impeller 64, so that sectional spaces 68 of different volume form between the individual spokes of the impeller 64 and the liquid ring 66. An intake slot via which the medium to be drawn in is drawn in via the suction connection 30 is provided in the housing 62 at the end face at the position identified by reference numeral 70. Due to the eccentric arrangement, the medium to be pumped is compressed in the course of the revolution of the impeller 64 and is expelled via a pressure '13 slot to the pressure connection 34 at the position identified by reference numeral 72. The additional port 35 is arranged between the intake slot 70 and the pressure slot 72 in the housing 62 and is connected to the working space, which is formed by the individual sectional spaces 68. Depending on the position of the additional port 35, the suction capacity, prevailing at this position, of the liquid ring pump 28 varies with regard to both the prevailing vacuum and the delivery quantity. In addition, the suction capacity can be varied by selection of the diameter of the additional port 35. Although the vacuum at the additional port 35 is above the vacuum applied at the suction connection 30, it is sufficiently low in order to permit deaeration of the water chamber 22. The volumetric suction capacity for deaerating the water chamber 22 is also sufficiently high. Since the third deaerating line 24 is not connected to the suction connection 30, the liquid ring pump 28 is not additionally loaded by the additionally fed gas mixture G or is only barely subjected to additional loading by the latter. Slightly greater dimensioning, possibly necessary due to the connection of the third deaerating line 24, of the liquid ring pump 28 is in any case more favorable compared with a separate pumping system for the deaeration of the water chamber 22. A steam turbine plant of such a design with a uniform, central vacuum pumping arrangement 14 has essentially the following advantages: 1. On account of the use of steam D and air L as motive fluid T for the jet pump 26 - compared with the use exclusively of air L as motive fluid T - the liquid ring pump 28 can be -14 designed to be markedly smaller, since the steam D condenses in the liquid ring pump, and only the air proportion has to be compressed to atmospheric pressure. 2. The low-tension steam collecting in the sealing-steam circuit 50 is preferably completely directed via the vacuum pumping arrangement 14. In this case, it is not absolutely necessary for the entire quantity of the low-tension steam to be used as motive fluid T for the jet pump 26. By the feeding of the low-tension steam to the liquid ring pump 28 having the associated separator 38, the low-tension steam is condensed, so that a separate condensing system is not required for the low-tension steam. 3. For all the plant components which have to be connected to a vacuum system, the vacuum pumping arrangement 14 is provided as a central vacuum system. This makes possible a simple and cost-effective installation. In particular, it is not necessary to install a plurality of decentral vacuum pumping systems. 4. Due to the connection of the third deaerating line 24 to the additional port 35, a suction capacity provided virtually "for nothing" by the liquid ring pump 28 is utilized without the liquid ring pump 28 having to be of larger dimensions due to the connection of this third deaerating line 24. - 15 WE CLAIM 1. A steam turbine plant (2) having a vacuum pumping arrangement (14) which has a Jet pump (26) and a liquid ring pump (28) arranged in series one after the other, characterized in (hat a steam line (48) connected to a seating-steam circuit (50) for a turbine seal (52) and inended for reeding steam (D), collecting in the plant (2), as motive fluid (T) for the Jet pump (26) Is connected to the Jot pump (26). 2. The plant (2) as claimed in claim 1, characterized in that a gas line (42) for admixing air (L) for forming a steam/air mixture as motive fluid (T) Is connected to the steam line (48). 3. The plant (2) as claimed in claim 2, characterized in that the gas line (42) is also connected on the pressure side to the liquid ring pump (28) and In particular to a separator (38) assigned to the liquid ring pump (28). 4. The plant (2) as claimed in one of the preceding claims, characterized In that the vacuum pumping arrangement (14) is connected to a first condenser (8) via a first deserating line (12) for deaerating said first condenser (8), which is provided for condensing process steam (P) discharging from a steam turbine (4), in particular from a tow-pressure part of a steam turbine (4). 6. The plant (2) as claimed in one of the preceding claims, characterized tn that the vacuum pumping arrangement (14) is connected via a second deaerating ine (20) to a second condenser (18), which is assigned to an auxiary turbine (16). 16 6. ' The plant (2) as claimed in claim 4 or 5, characterized in that the condenser {8, 18), for a cooling liquid, has a water chamber (22), which, in order to deaerate it, is connected to the vacuum pumping arrangement (14) via a third deaerating line (24). 7. The plant (2) as claimed in claim 6, characterized in that the liquid ring pump (28) has an additional port (35), to which the third deaerating line (24) is connected. 8. The plant (2) as claimed in claim 7, characterized in that the additional port (35) is arranged between a suction connection (30) and a pressure connection (34) in the housing (62) of the liquid ring pump (28) and is connected to a working space (68) forming during operation. 9. A method of operating a steam turbine plant (2), in which a plant component (8, 18, 22) is deaerated by means of a vacuum pumping arrangement (14) which has a jet pump (26) and a liquid ring pump (28) arranged in series one after the other, characterized in that steam (D) collecting in the steam turbine plant (2) as sealing steam (S, D) for a turbine seal (52) is fed as motive fluid (T) to the jet pump (26). 10. The method as claimed in claim 9, characterized in that the motive fluid (T) used is a steam/air mixture (D, L). 11. The method as claimed in claim 10, characterized in that approximately an identical ratio of steam (D) and air (L) is set for the mixture (D, L). - 17- -18- 12. The method as claimed in one of claims 9 to 11, characterized in that the sealing steam (S, D) is condensed in the vacuum pumping arrangement (14). 13. The method as claimed in one of claims 9 to 12, characterized in that a condenser (8, 18) of a steam turbine (4, 16) is deaerated. 14. The method as claimed in claim 13, characterized in that a water chamber (22) of the condenser (8, 18) is deaerated. 15. The method as claimed in claim 14, characterized in that, to deaerate the water chamber (22), the saturated water- chamber air (WL) collecting therein is drawn off via an additional port (35) in the liquid ring pump (28). A steam turbine plant (2) having a vacuum pumping arrangement (14) which has a jet pump (26) and a liquid ring pump (28) arranged in series one after the other, characterized in that a steam One (48) connected to a seating-steam circuit (50) for a turbine seal (52) and Mended for feeding steam (D), collecting in the plant (2), as motive fluid (T) for the jet pump (26) is connected to the jet pump (26).

Documents:

00456-kolnp-2003 abstract.pdf

00456-kolnp-2003 claims.pdf

00456-kolnp-2003 correspondence.pdf

00456-kolnp-2003 description (complete).pdf

00456-kolnp-2003 drawings.pdf

00456-kolnp-2003 form-1.pdf

00456-kolnp-2003 form-18.pdf

00456-kolnp-2003 form-2.pdf

00456-kolnp-2003 form-26.pdf

00456-kolnp-2003 form-3.pdf

00456-kolnp-2003 form-5.pdf

00456-kolnp-2003 letters patent.pdf

00456-kolnp-2003 priority document others.pdf

00456-kolnp-2003 priority document.pdf

456-KOLNP-2003-(11-01-2012)-CORRESPONDENCE.pdf

456-KOLNP-2003-(11-01-2012)-OTHERS.pdf

456-KOLNP-2003-(12-04-2012)-CORRESPONDENCE.pdf

456-KOLNP-2003-CORRESPONDENCE 1.3.pdf

456-KOLNP-2003-CORRESPONDENCE-1.1.pdf

456-KOLNP-2003-CORRESPONDENCE-1.2.pdf

456-KOLNP-2003-FORM 13.pdf

456-KOLNP-2003-FORM 27-1.1.pdf

456-KOLNP-2003-FORM 27.pdf

456-KOLNP-2003-FORM-27.pdf

456-KOLNP-2003-OTHERS.pdf