EP2805026B1 - Turbine system with three turbines coupled to a central gearbox and method for operating a work machine - Google Patents

Description

The present invention relates generally to the field of turbine technology. The present invention relates in particular to a turbine system which has a plurality of turbines which are connected in series with respect to the flow of a working fluid and which can jointly drive a working machine. The present invention further relates to a turbine system having such a turbine system and a work machine mechanically coupled to the turbine system. In addition, the present invention relates to a method for operating a work machine by means of such a turbine system.

Turbines and in particular steam turbines are often used to convert thermal energy into mechanical energy. When operating known turbine or steam turbine systems, the working fluid or the steam is typically expanded along the direction of flow via a turbine with a turbine shaft. The turbine can be a so-called multi-stage turbine, which has several identical or different arrangements, each consisting of a rotor blade row (rotor blade row) and a stator blade row (guide blade row). The turbine shaft drives a work machine either directly or indirectly via a separate gear.

Alternatively, a turbine system is also known in which two separate turbines, each having a turbine housing, are flowed through in succession by the working fluid. In this case, the two turbines are arranged on one or on two separate transmission shafts. The two turbines drive the working machine via the gear shaft. Due to the usually small number of rows of rotor blades in both turbines, which are typically used for such a turbine system, the thermodynamic efficiency of such a turbine system is comparatively low. Furthermore, the disclosure of FR 633903 A may be helpful in understanding the present invention.

The present invention has for its object to provide an easy to implement turbine system, a turbine system and a method for operating a machine with a good thermodynamic efficiency.

This object is achieved by the subject matter of the independent claims. The invention consequently relates to a turbine system according to claim 1, a turbine system with such a turbine system according to claim 11 and a method for operating a work machine using such a turbine system according to claim 12. Advantageous embodiments, further features and details of the present invention result the dependent claims, the description and the drawings. Features and details that are described in connection with the turbine system apply, of course, also in connection with the turbine system and the method for operating a work machine. The same applies in reverse, so that reference can always be made to one another with regard to the disclosure of the individual aspects of the invention.

According to a first aspect of the invention, a turbine system is described which has (a) a first turbine, (b) a second turbine, (c) a third turbine, (d) a central transmission which is mechanically coupled on the input side to the three turbines and which has a mechanical connection on the output side to which a mechanical energy-absorbing work machine can be connected, (e) a first fluid line for passing on a working fluid from the first turbine to the second turbine, (f) a second fluid line for passing on the working fluid from the second Turbine to the third turbine, (g) a first connection device which is assigned to the first fluid line and which is set up such that a first partial mass flow of the working fluid can be removed from the first fluid line or can be supplied to the first fluid line, and (h) a second connection device which of the second fluid line is assigned and which is set up in such a way that a second partial mass flow of the working fluid can be removed from the second fluid line or can be supplied to the second fluid line. The turbines of the turbine system are connected in series with respect to the flow path of the working fluid, the second turbine being connected downstream of the first turbine and the third turbine being connected downstream of the second turbine.

The turbine system described is based on the knowledge that in a turbine system which has at least three turbines, not all turbines have to be arranged on a common shaft, but can be mechanically coupled to a central transmission. The working fluid, which has done work in the first turbine and then leaves the first turbine, can be transferred to the second turbine by means of the first fluid line. In a corresponding manner, the working fluid, which has done work in the second turbine and then leaves the second turbine, can be transferred to the third turbine by means of the second fluid line.

Compared to a conventional turbine system, in which all turbines are coupled with a common, relatively long shaft, the described turbine system with a central transmission offers the possibility of arranging the individual turbines no longer along an elongated row, but flexibly in a spatially compact construction. The described turbine system can thus be implemented within a comparatively small installation space. Due to the possibility of flexibly choosing the spatial arrangement of the individual turbines, the turbine system described can be adapted in a relatively simple manner to a specification specified by a customer. In addition, the turbine system described can be converted relatively easily if necessary and, for example, can be adapted accordingly in the event of changed operating parameters. In the event of a revision, maintenance or repair, particularly easy accessibility of the individual components of the turbine system described are guaranteed. Furthermore, the turbine system described can be implemented comparatively inexpensively.

Another advantage of the turbine system described in this document is that, compared to known turbine systems in which the individual turbines are coupled to a common, relatively long shaft, several short individual turbine shafts are used. In this way, a particularly high so-called quick start capability can be achieved in an advantageous manner.

In the turbine system described, two successive turbines are each coupled to one another by means of a fluid line. Since the turbines are no longer arranged along a row due to the coupling to the central transmission, the fluid lines each have a course which allows a simple supply and / or discharge of working fluid. This means that the described connection devices, which can each be implemented by means of a simple branching such as a T-piece, can be installed in the corresponding fluid line without accessibility or space problems hindering the installation of the corresponding connection device. Partial mass flows of the working fluid of the relevant fluid line can thus be supplied from the outside in a simple manner or can be discharged to the outside from the relevant fluid line.

The turbines described can in particular be turbines which each take energy from the working fluid only because of an expansion of the working fluid and which, in addition to an expansion stage, have no compressor stage.

The working fluid may be any pressurized fluid capable of performing mechanical work as it passes through the turbine. The working fluid can in particular be steam (eg water vapor) be generated by a water vapor generator. The water vapor generator can be a power plant which generates the water vapor primarily for the purpose of use by the turbine system described. However, the water vapor generator can also be a system which primarily generates the water vapor for other processes (e.g. for the purpose of cleaning and / or sterilization) and which only supplies the water vapor to the turbine system described when the water vapor is not just for these processes is used.

The working fluid can also be a simple gas that has been previously compressed to temporarily store energy. The gas compression can be carried out, for example, by a compressor operated with electrical energy in a period in which, for example, a larger quantity of electrical energy is provided by regenerative energy sources than is currently being consumed.

The turbines described can be any type of turbine in which the working fluid drives a rotor. Of course, the structural design of the turbines depends in a known manner on the working fluid used. If steam is used as the working fluid, these are so-called steam turbines. If the working medium is a gas under pressure, then one usually speaks of gas expansion turbines.

According to one exemplary embodiment of the invention, the turbine system further comprises (a) a first control device which is assigned to the first connection device for setting the strength of the first partial mass flow and / or (b) a second control device which is assigned to the second connection device for setting the strength of the second partial mass flow.

The control devices described can each have an actuator which, for example, due to a Narrowing or widening its cross-section can determine the strength or the height of the respective (partial) mass flow, which is fed into the relevant fluid line from the outside via the connecting device in question or is discharged to the outside through the relevant fluid line. Furthermore, the control devices described can each have a suitable sensor, which detects a state variable, such as the pressure of the working fluid in the relevant fluid line, the actuator, for example an adjustable valve or an adjustable throttle, based on the detection value of this state variable, the relevant (part) Mass flow can set so that this state variable remains at least approximately constant even with changing operating conditions. Thus, by skillfully regulating the (partial) mass flows of the working fluid, conditions can be created or maintained for each turbine, which ensure high efficiency for each individual turbine and, of course, for the entire turbine system.

It is pointed out that decoupling or extracting a partial mass flow does not necessarily mean that this partial mass flow is lost for energy generation. This partial mass flow can namely be supplied to the described turbine system again at another point, for example, via another connection device. In a corresponding manner, a (partial) mass flow fed into the turbine system from outside can also have been taken from the main mass flow of the turbine system described elsewhere by means of another connection device. In this context, the use of at least one intermediate storage for the temporary storage of working fluid is also possible.

Expressed vividly, the two control devices, in conjunction with the associated connection devices, offer the possibility of realizing precisely defined intermediate pressure stages, of which the working fluid removed in a simple and controlled manner and / or to which the working fluid can be supplied in a simple and controlled manner. This significantly increases the flexibility of the entire turbine system, particularly when there are load changes.

According to a further exemplary embodiment of the invention, the first turbine and the second turbine are coupled to the central transmission via a common shaft, in particular one of the two turbines on a first side of the central transmission and the other of the two turbines on a second side of the central transmission is arranged. The first side is opposite the second side. This has the advantage that the two turbines mentioned are mechanically coupled to the central transmission by means of a common coupling element and in particular by means of a common pinion, the common coupling element being attached to the common shaft. As a result, only two coupling elements are required on the transmission side, so that the at least three turbines in total can be coupled to the central transmission.

The common shaft can be a one-piece or a multi-piece shaft. In the case of a multi-piece shaft, however, the several pieces of the common shaft should be connected to one another so firmly that the rotors of the two turbines are coupled to one another in a rotationally fixed manner.

The rotors of the two turbines can be arranged "on the fly", ie without a bearing on the turbine side in the respective turbine housing. The rotor or the entire turbine is located outside the bearing points of the common shaft. This has the advantage that a suitable mounting of the common shaft only has to be present in or on the central transmission. A suitable bearing can be implemented, for example, by means of two bearings, one of the two bearings on the first side and the other of the two bearings is arranged on the opposite second side of the central transmission.

According to a further exemplary embodiment of the invention, the first turbine and the third turbine are coupled to the central transmission in such a way that the first turbine can be operated with a first rotation frequency and the third turbine with a second rotation frequency, the first rotation frequency being different from the second rotation frequency . By choosing suitable transmission ratios in the coupling between the turbine in question and the central transmission, a specific ratio between the first rotation frequency and the second rotation frequency can be set. By a suitable choice of the gear ratio, each turbine can then be operated in an optimal speed range. A particularly high efficiency of the individual turbines and thus of the entire turbine system can thus be achieved.

Expressed clearly, the shaft speeds of the first turbine and the second turbine can be adapted to the respective turbines and in particular to the pressure levels assigned to the respective turbines. As a result, the described turbine system can be optimized in terms of its efficiency or in terms of its efficiency in a simple manner.

According to a further exemplary embodiment of the invention, at least one of the three turbines is a radial turbine.

Since a radial turbine typically has a shorter design than an axial turbine, the entire turbine system can thus be implemented in a particularly compact design.

Of the majority of the turbines connected in series, in particular that turbine which has the (compressed) Working fluid is supplied first, be designed as a radial turbine. This has the advantage that a radial turbine then represents the first control stage for the entire turbine system, by means of which the total mass flow of working fluid which flows through the entire turbine system is adjusted in a controlled manner. For this purpose, this (first) radial turbine can be equipped with suitable control valves, by means of which the total mass flow of working fluid can be adjusted in a known manner.

According to a further exemplary embodiment of the invention, at least one of the three turbines is an axial turbine.

The axial turbine, in which the working fluid flows in the axial direction through the corresponding turbine housing and thereby drives the rotor or the rotor, can consist of one stage or preferably of several stages, with one stage (a) in each case a row on the rotor or on Rotor-mounted rotating blades and (b) has a series of stationary vanes attached to the housing.

According to a further exemplary embodiment of the invention, the rotor of the axial turbine is coupled to an axial shaft which is mounted on the side of the central transmission and which is arranged in a housing of the axial turbine without bearing. This means that the rotor or the axial shaft of the axial turbine is arranged "on the fly" on one side. Bearing is therefore only provided on the section of the axial shaft, which section lies outside the axial turbine and is assigned to the central transmission. In this case, the bearing on the central transmission can be implemented by means of one or more bearings which are axially offset from one another.

In simple terms, this means that there is a mechanical connection between the axial turbine and the central gearbox without intermediate bearings. The axial shaft is not mounted in the turbine housing but only in or on a housing of the central gear.

In this context, it is pointed out that a "flying" bearing in the turbine housing includes offers the advantage that changes in expansion in the case of fluctuating temperatures, which occur in particular during load changes, do not lead to tensioning of the axial shaft in relation to bearings in the turbine housing.

According to a further exemplary embodiment of the invention, the rotor of the axial turbine has a plurality of turbine stages, each turbine stage arranged around the axial shaft (a) having a row of rotatable rotor blades attached to the rotor and (b) a row of stationary guide vanes attached to the housing. This has the advantage that, compared to an axial turbine with only one turbine stage, a higher degree of efficiency can be achieved.

According to a further exemplary embodiment of the invention, the rotor blades of a row are attached to a rotor blade carrier and the plurality of rotor blade carriers are fixed on the axial shaft by means of a pulling device.

The pulling device can be, for example, a so-called tie rod, which comprises a thread formed on the axial shaft and a nut engaging in the thread. As a result, several rotor blade carriers can be fixed in a rotationally fixed manner on the axial shaft in a particularly simple and nevertheless reliable manner.

According to a further exemplary embodiment of the invention, the turbine system further comprises (a) a fourth turbine which is mechanically coupled to the central transmission, (b) a third fluid line for passing the working fluid from the third turbine to the fourth turbine and (c) one third connection device which is assigned to the third fluid line and which is set up in such a way that a third partial mass flow of the working fluid can be removed from the third fluid line or can be supplied to the third fluid line is. This means that the mechanical connection, which can drive the machine, is now driven by a total of at least four turbines. As a result, the efficiency of the turbine system described can be further improved.

It is pointed out that more than four turbines can be coupled directly or indirectly to the central transmission. A fluid line, which is provided with a connection device, is preferably provided between two turbines which are adjacent from the point of view of the flow direction of the working medium, so that a corresponding partial mass flow of the working fluid can be removed from the relevant fluid line or can be supplied to the relevant fluid line. A control device is further preferably assigned to the connection device in question, so that the strength of the partial mass flow in question can be set precisely and operation which is optimal with respect to the efficiency of the turbine system can be ensured.

According to a further aspect of the invention, a turbine system is described which has (a) a turbine system of the type described above and (b) a work machine which is coupled to the mechanical connection of the central transmission.

The turbine system described is based on the knowledge that the above-mentioned Turbine system can be mechanically coupled to a working machine, so that energy contained in the working fluid can be removed from the working fluid and transferred to the working machine in a mechanical manner.

A rotor of the working machine can be mechanically coupled to the mechanical connection of the central transmission using a coupling or a flange.

The working machine can in particular be an electrical generator, which can be used to generate electricity. However, the working machine can also be a mechanical machine which uses the mechanical energy that is supplied to it by the turbine system described in a suitable manner for performing mechanical activities. The work machine can be, for example, a pump, a compressor, a fan and / or a press.

According to a further aspect of the invention, a method for operating a work machine is described. The described method comprises (a) providing a working fluid containing an energy, (b) supplying the working fluid to a turbine system of the type described above, the turbine system drawing at least part of the energy of the working fluid and at least part of the extracted energy in converts mechanical work, and (c) operating the work machine with the converted mechanical work.

The method described is also based on the knowledge that when using the above-mentioned Turbine system the machine can be operated in an efficient manner. In accordance with generally recognized basic principles of thermodynamics, the energy is extracted from the working fluid and converted into mechanical energy, which is then transferred to the working machine by means of a purely mechanical coupling.

In this context, the term “energy-containing working fluid” can be understood in particular to mean that the working fluid has been subjected to energy thermodynamically, so that the working fluid has, in particular, a high temperature and / or a high pressure. If the working fluid is a vapor, for example water vapor, then the hot and / or high-pressure water vapor additionally contains an evaporation energy which occurs when the vapor condenses leads to the release of condensation energy, which can then also be converted into mechanical work.

It is pointed out that embodiments of the invention have been described with reference to different subject matter of the invention. In particular, some embodiments of the invention are described with device claims and other embodiments of the invention with method claims. However, upon reading this application it will be immediately apparent to the person skilled in the art that, unless explicitly stated otherwise, in addition to a combination of features that belong to a type of subject matter of the invention, any combination of features that belong to different types of Objects of the invention belong.

Figur 1

zeigt in einer schematischen Darstellung eine Turbinenanlage mit vier Dampfturbinen, welche über ein gemeinsames Getriebe eine Arbeitsmaschine antreiben.

Figur 2

zeigt in einer perspektivischen Darstelllung eine Turbinenanlage mit drei Dampfturbinen, welche gemeinsam einen elektrischen Generator antreiben.

Figur 3

zeigt ein Turbinensystem mit einer Radialturbine und zwei Axialturbinen, welche über ein gemeinsames Getriebe eine Arbeitsmaschine antreiben können.

Figur 4

zeigt ein Turbinensystem mit einer Radialturbine und drei Axialturbinen, welche über ein gemeinsames Getriebe eine Arbeitsmaschine antreiben können.

Further advantages and features of the present invention result from the following exemplary description of currently preferred embodiments.

Figure 1

shows a schematic representation of a turbine system with four steam turbines which drive a work machine via a common gear.

Figure 2

shows a perspective view of a turbine system with three steam turbines, which together drive an electric generator.

Figure 3

shows a turbine system with a radial turbine and two axial turbines, which can drive a work machine via a common gear.

Figure 4

shows a turbine system with a radial turbine and three axial turbines, which can drive a work machine via a common gear.

It is pointed out that features or components of different embodiments which are identical or at least functionally the same with the corresponding features or components of the embodiment are provided with the same reference symbols or with other reference symbols which are only in their first digit of the reference number distinguish a (functionally) corresponding feature or a (functionally) corresponding component. In order to avoid unnecessary repetitions, features or components that have already been explained on the basis of a previously described embodiment are no longer explained in detail later.

It is also pointed out that the embodiments described below represent only a limited selection of possible embodiment variants of the invention. In particular, it is possible to combine the features of individual embodiments in a suitable manner, so that a multitude of different embodiments can be regarded as obvious for the person skilled in the art with the embodiment variants explicitly shown here.

Figure 1 shows a schematic representation of a turbine system 100 according to an embodiment of the invention. The turbine system 100 has a turbine system 110 which drives a work machine 120. The work machine 120 can in particular be an electrical generator that can be used to generate electricity. However, the work machine 120 can also be any mechanical machine that uses the mechanical energy that is supplied to it by the turbine system 110 in a suitable manner for performing mechanical activities, for example for pumping, compressing, and / or for pressing processes.

Turbine system 110 has four steam turbines, a first steam turbine 151, a second steam turbine 152, a third steam turbine 153 and a fourth steam turbine 154. How out Figure 1 as can be seen, these steam turbines 151, 152, 153 and 154 are connected in series with respect to the general flow direction of a working fluid. The working fluid, which is water vapor according to the exemplary embodiment shown here, flows into a fluid inlet 116, strongly overheated by a water vapor generator. A corresponding one Inlet mass flow 116a of water vapor then flows into the first steam turbine 151, in which the water vapor performs mechanical work in a known manner and thereby in Figure 1 drives not shown rotor of the first steam turbine 151.

The water vapor emerging from the first steam turbine 151, which still contains a considerable amount of energy which was not converted into mechanical work by the comparatively short first steam turbine 151, then flows via a first fluid line 161 into the second steam turbine 152, in which also in the energy contained in the water vapor is converted into mechanical work.

The first fluid line 161 has a first connection device 171, which according to the exemplary embodiment shown here is a simple branch, for example a so-called T-piece. A first partial mass flow 171a of working fluid can be coupled out of the entire mass flow to a first fluid connection 176 via the connection device 171, or an additional mass flow of working fluid can be fed from the first fluid connection 176 into the first fluid line. In this way, the energy which is supplied to the second steam turbine 152 can be adjusted and the power of the entire turbine system 110 can thus be adapted.

The first connection device 171 or the first fluid line 161 is assigned a first control device 171b, which has a pressure sensor (not shown) with which the pressure of the working fluid in the fluid line 161 is detected. By means of an adjustable valve, also not shown, the (partial) mass flow can be adjusted based on the detected pressure in such a way that the pressure remains at least approximately constant even under changing operating conditions. Thus, by skillfully regulating the (partial) mass flows of the working fluid, the steam turbine 152 can be operated in an optimal operating mode. To this In this way, a high degree of efficiency can be guaranteed for the steam turbine 152 and thus of course also for the entire turbine system 110.

The water vapor emerging from the second steam turbine 152, which still contains a considerable amount of energy which has not yet been used, then flows into the third steam turbine 153 via a second fluid line 162. Just as with the first fluid line 161, the a (second) connection device 172 designed as a T-piece and a (second) control device 172b are arranged in the second fluid line 162, so that a second partial mass flow 172 is likewise transferred in a controlled manner to a second fluid connection 177 or from the second fluid connection 177 into the second fluid line 162 can be fed.

In a corresponding manner, the third steam turbine 153 and the fourth steam turbine 154 connected downstream of the third steam turbine 153 are connected to one another via a third fluid line 163. Furthermore, in the third fluid line there is a third connection device 173, via which a third partial mass flow 173a of water vapor can be branched off from the third fluid line 163 and fed to a third fluid connection 178 and / or via which additional water vapor from the third fluid connection 178 into the third fluid line 163 can be fed. A third control device 173b ensures that the corresponding removal or supply of water vapor takes place in a controlled manner.

It is pointed out that the pressure sensor of the respective control device 171b, 172b, 173b is preferably arranged upstream in the respective fluid line 161, 162, 163 in relation to the branching of the respective connection device 171, 172, 173. Furthermore, the adjustable valve of the respective control device 171b, 172b, 173b is in relation to the branching of the respective connection device 171, 172, 173 is preferably arranged downstream in the respective fluid line 161, 162, 163. In particular, the adjustable valve can be arranged directly in front of or on the housing of the next turbine.

At a fluid outlet 118, an outlet mass flow 118a of water vapor emerges which has flowed through all the turbines 151, 152, 153 and 154 or which has been fed into the turbine system 110 via one of the fluid connections 176, 177 or 178. The escaping water vapor can then be fed to a heater (not shown) in a known manner. This heater can in turn be coupled to the fluid inlet 116, so that a closed circuit of working fluid or water vapor can be implemented.

How out Figure 1 As can be seen, the rotors of the steam turbines 151 and 152 are connected to one another via a common shaft 131a. This means that the rotation frequency of the steam turbines 151 and 152 is the same. Alternatively, a gear (not shown) could also be connected between the two rotors of the steam turbines 151 and 152, so that a first rotational frequency of the rotor of the first steam turbine 151 and a second rotational frequency of the rotor of the second steam turbine 152 are in a fixed relationship to one another. In a corresponding manner, the two rotors of the steam turbines 153 and 154 are connected to one another via a common shaft 132a or, if appropriate, mechanically coupled to one another via an additional gear.

A central component of the turbine system 110 described here is a central gear 130, which has a gear 134 and two pinions. A first pinion 131 of the two pinions is attached to the shaft 131a. The second pinion 132 is attached to the shaft 132a. Both pinions 131 and 132 are in engagement with the gear 134. The central gear 130 also has a central drive shaft 136, which connects the gear 134 and the engine 120 to one another.

Figure 2 shows a perspective view of a turbine system 200 according to another embodiment of the invention. The turbine system 200 has a base plate 202 on which at least the main components of the turbine system 200 are attached or mounted. The turbine system 200 has (a) a first steam turbine 251 designed as a radial turbine, (b) a second turbine 252 designed as an axial turbine and (c) a third steam turbine 253 also designed as an axial turbine 253. All turbines 251, 252 and 253 or the rotors of these turbines 251, 252 and 253 are coupled to one another via a central gear 230. The central transmission 230 is mechanically coupled on the output side via a drive shaft 236 to a work machine 220 designed as an electrical generator.

An inlet mass flow 216a of working fluid is supplied to the first steam turbine 251. The strength of this inlet mass flow 216a, which is regulated by means of a plurality of control valves 251a, thus essentially determines the output of the entire turbine system 200. Working fluid emerging from the first steam turbine 251 is fed to the second steam turbine 252 via a first fluid line 261. Working fluid emerging from the second steam turbine 252 is supplied to the third steam turbine 253 via a second fluid line 262.

In order to regulate the mass flow of working fluid between two steam turbines 251 and 252 or 252 and 253 that are adjacent with respect to the flow direction of the working fluid, a first connection device 271 is located in the first fluid line 261 together with an in Figure 2 First control device, not shown, so that a first partial mass flow 271a can be coupled out of the first fluid line 261 or, alternatively, a mass flow, not shown, can be fed into the first fluid line 261. In a corresponding manner, a second connection device 272 is located in the second fluid line 262 together with one in Figure 2 Second control device, not shown, so that a second partial mass flow 272a can be coupled out of the second fluid line 262 or, alternatively, a mass flow, not shown, can be fed into the second fluid line 262.

An outlet mass flow 218a of working fluid which has flowed through all the turbines 251, 252 and 253 or which has been fed into the turbine system 200 via one of the connection devices 271 or 272 is then fed to a heater (not shown). This heater can in turn provide the inlet mass flow 216a, so that a closed circuit of working fluid or water vapor can be implemented.

Figure 3 shows a turbine system 310 with a first steam turbine 351 designed as a radial turbine, with a second steam turbine 352 designed as an axial turbine and with a third steam turbine 353 also designed as an axial turbine. The first steam turbine 351 and the second steam turbine 352 are connected to one another via a first fluid line (not shown) . The first steam turbine 351 has a first housing 351a, the second steam turbine 352 has a second housing 352a and the third steam turbine 353 has a third housing 353a.

As in the exemplary embodiments shown above, the first fluid line is also assigned a first connection device, also not shown, and a first control device, also not shown. The second steam turbine 352 and the third steam turbine 353 are connected to one another via a second fluid line, not shown, to which a second connection device, also not shown, and a second control device, also not shown, are assigned.

The three steam turbines are mechanically coupled to one another by means of a central transmission 330. With the transmission 330 there are both a first pinion 331 and a second pinion 332 in engagement with a gear 334. A ratio between (a) a first number of teeth of the first pinion 331, which is arranged on a shaft 331a, which the rotors of the two steam turbines 351 and 352, and (b) a second number of teeth of the second pinion 332, which is arranged on a shaft 332a of the rotor of the third steam turbine 353, the ratio between the rotation frequency of the rotors of the first and the second steam turbine 351 and 352 and the rotation frequency of the rotor of the third steam turbine 353. According to the exemplary embodiment shown here, the first pinion 331 has more teeth than the second pinion 332, so that the rotation frequency of the rotors of the first and the second steam turbine 351 and 352 is greater than the rotation frequency of the rotor of the third steam turbine 353.

The gear 334 is arranged on a central drive shaft 336, which is mounted in a housing of the central transmission 330 by means of two bearings 338. In Figure 3 is provided at the right end of the central drive shaft 336 a mechanical connection 337 designed as a flange, to which one in Figure 3 Drive machine, not shown, can be connected.

How out Figure 3 As can be seen, the two axial turbines 352 and 353 each have a multi-stage configuration of one guide vane and possibly one rotor vane. A rotor blade 381a and a guide blade 381b are assigned to a first stage 381 of the multi-stage axial turbine 353. A rotor blade 382a and a guide blade 382b are assigned to a second stage 382 of the multi-stage axial turbine 353. A rotor blade 383a and a guide blade 383b are assigned to a third stage 383 of the multi-stage axial turbine 353.

The rotor blades 381a, 382a and 383a are arranged on an axial shaft 385 of the steam turbine 353. The axial shaft 385 is non-rotatably connected to the shaft 332a.

According to the embodiment shown here, adjacent rotor blades, i.e. the rotor blades 381a and 382a as well as the rotor blades 382a and 383a are arranged on the axial shaft 385 in a rotationally fixed manner by means of an axial front toothing. A tie rod connection, which is realized by means of a nut 386 in connection with an external thread formed on the axial shaft 385, ensures that the rotor blades 381a, 381b and 381c are firmly locked on the axial shaft 385.

At this point it is pointed out that for reasons of clarity in Figure 3 the different stages 381, 382 and 383 and the respectively associated components are identified only in the steam turbine 353 by reference numerals.

How out Figure 3 can also be seen, the rotors of the two axial turbines 352 and 353 are overhung. This means that the rotors of the two steam turbines 352 and 353 are not mounted in the respective turbine housing 352a or 353a but only (by means of the shaft 332a) on the housing of the central transmission 330. For this purpose, a bearing 332b is provided on the left and right on the housing of the central transmission 330. No bearing elements are present in the turbine housing 352a or 353a in accordance with a "flying arrangement" of the respective rotor.

It is pointed out that, according to the exemplary embodiment shown here, the bearings 332b are radial bearings. An axial bearing is realized here by means of the second pinion 332, which, as in FIG Figure 3 can be seen, each has a shoulder on the left and right, the two shoulders engaging with the gear 334 in the axial direction. In this way, one generated during the operation of the steam turbine 353 Axial thrust to the left over the two shoulders of the pinion 332 and the gear 334 transmitted to the bearing 338 and taken up by this.

Figure 4 shows a turbine system 410 which differs from that shown in FIG Figure 3 Turbine system 310 shown only differs in that a fourth steam turbine 454, which is designed as an axial turbine and has a housing 454a, is additionally arranged on the shaft 332a. In this exemplary embodiment, the central drive shaft 336 is thus driven by a total of four steam turbines, the fourth steam turbine 454 being connected downstream of the third steam turbine 353 by means of a third fluid line (not shown). Correspondingly, the third fluid line is assigned a second connection device, not shown, and a second control device, also not shown, for regulating the amount of working fluid withdrawn from the third fluid line and / or for regulating the amount of additional working fluid fed into the third fluid line.

Claims (12)

1. A turbine system (110, 310, 410), comprising
   a first turbine (151, 251, 351),
   a second turbine (152, 252, 352),
   a third turbine (153, 253, 353),
   a central gearbox (130, 230, 330), which is mechanically coupled on the input side to the three turbines (151, 251, 351; 152, 252, 352; 153, 253, 353) and which comprises a mechanical connector (337) on the output side, to which a work machine (120, 220) which absorbs mechanical energy can be attached,
   a first fluid line (161, 261) for forwarding a work fluid from the first turbine (151, 251, 351) to the second turbine (152, 252, 352),
   a second fluid line (162, 262) for forwarding the work fluid from the second turbine (152, 252, 352) to the third turbine (153, 253, 353),
   a first connection device (171, 271), which is assigned to the first fluid line (161, 261) and which is set up in such a way that a first partial mass flow (171a) of the work fluid can be drawn from the first fluid line (161, 261) or can be supplied to the first fluid line (161, 261), and
   a second connection device (172, 272), which is assigned to the second fluid line (162, 262) and which is set up in such a way that a second partial mass flow (172a) of the work fluid can be drawn from the second fluid line (162, 262) or can be supplied to the second fluid line (162, 262),
   wherein the three turbines (151, 251, 351; 152, 252, 352; 153, 253, 353) are connected in series with regard to a flow path of the work fluid, wherein the second turbine (152, 252, 352) is connected downstream of the first turbine (151, 251, 351) and the third turbine (153, 253, 353) is connected downstream of the second turbine (152, 252, 352).
2. The turbine system (110, 310, 410) according to the preceding claim, further comprising a first control device (171b), which is assigned to the first connection device (171), for adjusting the strength of the first partial mass flow (171a) and/or
   a second control device (172b), which is assigned to the second connection device (172, 272), for adjusting the strength of the second partial mass flow (172a).
3. The turbine system (110, 310, 410) according to any one of the preceding claims, wherein
   the first turbine (151, 251, 351) and the second turbine (152, 252, 352) are coupled to the central gearbox (130, 230, 330) via a common shaft (131a, 331a), wherein in particular one of the two turbines (151, 251, 351; 152, 252, 352) is arranged on a first side of the central gearbox (130, 230, 330) and the other of the two turbines (151, 251, 351; 152, 252, 352) is arranged on a second side of the central gearbox (130, 230, 330), wherein the first side is opposite the second side.
4. The turbine system (110, 310, 410) according to any one of the preceding claims,
   wherein the first turbine (151, 251, 351) and the third turbine (153, 253, 353) are coupled to the central gearbox (130, 230, 330) in such a way that the first turbine (151, 251, 351) can be operated at a first rotation frequency and the third turbine (153, 253, 353) can be operated at a second rotation frequency, wherein the first rotation frequency is different from the second rotation frequency.
5. The turbine system (110, 310, 410) according to any one of the preceding claims, wherein
   at least one of the three turbines (151, 251, 351; 152, 252, 352; 153, 253, 353) is a radial turbine.
6. The turbine system (110, 310, 410) according to any one of the preceding claims, wherein
   at least one of the three turbines (151, 251, 351; 152, 252, 352; 153, 253, 353) is an axial turbine.
7. The turbine system (110, 310, 410) according to the preceding claim, wherein the rotor of the axial turbine (353) is coupled to an axial shaft (385), which is mounted on the side of the central gearbox (330) and which is arranged in a bearing-free manner in a housing (353a) of the axial turbine (353).
8. The turbine system (110, 310, 410) according to the preceding claim, wherein
   the rotor of the axial turbine (353) comprises a plurality of turbine stages (381, 382, 383), wherein each turbine stage (381, 382, 383) comprises, arranged around the axial shaft (385),

   (a) a series of rotatable rotor blades (381a, 382a, 383a) attached to the rotor and

   (b) a series of stationary stator blades (381a, 381b) attached to the housing (353a).
9. The turbine system (110, 310, 410) according to the preceding claim, wherein
   the rotor blades (381a, 382a, 383a) of one series are attached to one rotor-blade support and wherein
   the plurality of rotor-blade supports are fixed on the axial shaft (385) by means of a tensioning device (386).
10. The turbine system (110, 410) according to any one of the preceding claims, further comprising
    a fourth turbine (154, 454), which is mechanically coupled to the central gearbox (130, 330),
    a third fluid line (163) for forwarding the work fluid from the third turbine (153, 353) to the fourth turbine (154, 454) and
    a third connection device (173), which is assigned to the third fluid line (163) and which is set up in such a way that a third partial mass flow (173a) of the work fluid can be drawn from the third fluid line (163) or can be supplied to the third fluid line (163).
11. A turbine installation (100, 200) comprising
    a turbine system (110, 310, 410) according to any one of the preceding claims, and
    a work machine (120, 220), which is coupled to the mechanical connector of the central gearbox (130, 230).
12. A method for operating a work machine (120, 220), the method comprising provision of a work fluid containing an energy,
    supplying of the work fluid to a turbine system (110, 310) according to any one of the preceding Claims 1 to 10 , wherein the turbine system (110, 310) draws at least part of the energy of the work fluid and converts at least part of the drawn energy into mechanical work, and
    operation of the work machine (120, 220) with the converted mechanical work.

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