Expansion plant and plant for generating electricity from heat

Description

[0001] The invention relates to an expansion plant according to claim 1 for generating electrical energy by means of a thermodynamic cycle process, comprising an expansion device operated by an expanding working medium of the thermodynamic cycle process and a generator driven by the expansion device.

[0002] With such expansion systems, the problem is to determine the generator's rotational speed as precisely as possible, since the frequency of the alternating voltage generated by the generator depends on the generator's rotational speed, and feeding electrical energy into a supply network only makes sense if the frequency of the alternating voltage generated by the generator matches the network frequency.

[0003] This problem is solved according to the invention in an expansion system of the type described above by providing the expansion system with a speed sensor which is coupled to a shaft of the expansion system which rotates proportionally to a rotor of the generator and which is designed as an electrical sensor generator which generates an electrical sensor signal.

[0004] The advantage of the solution according to the invention is that a sensor generator is a simple component that can be coupled to any shaft of the expansion system rotating proportionally to the rotor of the generator in order to generate an electrical voltage as a sensor signal, which allows a conclusion to be drawn about the rotational speed of the rotor of the generator.

[0005] In principle, both current and voltage can be evaluated as electrical sensor signals.

[0006] However, evaluating a current is more complex, as it must flow through a consumer and is therefore no longer proportional to the speed of the generator.

[0007] For this reason, it is particularly advantageous if a voltage signal is generated as the electrical sensor signal, which can be detected by a direct voltage measurement and is essentially proportional to the speed of the generator.

[0008] Such a voltage can be detected in particular without a significant current flow and therefore without additional circuitry.

[0009] The solution according to the invention can be implemented particularly advantageously if the sensor generator is arranged in an overall housing of the expansion system and, in particular, is exposed to the working medium and / or the lubricant in this housing.

[0010] This solution has the major advantage that the sensor generator can be easily integrated into the expansion system and also the advantage that no measures need to be taken to protect the sensor generator from lubricant and / or the working medium of the cycle process during integration.

[0011] Another advantageous solution provides that the sensor generator has a sensor rotor with permanent magnetization, which interacts with a stator having stator windings, wherein, when the sensor rotor rotates, a voltage dependent on the rotational speed of the sensor rotor occurs at the stator windings of the stator, which represents the sensor signal.

[0012] This solution has the particular advantage that, due to the permanent magnetization of the sensor rotor, the voltage occurring in the stator windings is essentially proportional, in particular proportional, to the rotational speed of the sensor rotor, so that the sensor signal allows a simple conclusion to be drawn about the rotational speed of the sensor rotor and thus also about the rotational speed of the rotor of the generator for generating electrical energy.

[0013] Furthermore, it is advantageous if the sensor rotor has a rare earth-based magnetic material to achieve permanent magnetization, since such a magnetic material makes it possible to ensure a high permanent magnetization of the sensor rotor.

[0014] It is particularly advantageous if the sensor generator is designed such that, at a generator speed that results in a frequency of the generated alternating voltage in the range of a mains frequency of a supply network receiving the electrical energy, it generates a voltage in the range between 30 V and 48 V, preferably between 40 V and 48 V.

[0015] This solution has the major advantage that generating the highest possible voltage by the sensor generator in the speed range relevant for evaluating the generator's rotational speed improves the accuracy of the speed measurement, without requiring the use of electrical components suitable for voltages above 48 V, thus enabling the sensor generator and evaluation electronics to be implemented with cost-effective components.

[0016] Regarding the installation of the sensor rotor of the sensor generator, a wide variety of options are conceivable.

[0017] For example, it would be conceivable to couple the sensor rotor to a shaft of the expansion system via a gear mechanism.

[0018] One particularly simple solution involves the sensor rotor of the sensor generator being directly coupled to a shaft end in a rotationally fixed manner and supported by it.

[0019] This greatly simplifies the installation of the sensor generator, as no bearing is required for the sensor rotor; instead, the sensor rotor of the sensor generator is supported via the shaft end.

[0020] One particularly practical solution involves arranging the sensor rotor on a rotor carrier connected to the shaft end.

[0021] In order to mount the rotor carrier in a simple manner, it has proven particularly useful if the rotor carrier is connected to the shaft end by means of a centering screw.

[0022] Furthermore, to improve the precision of the centering of the rotor carrier relative to the shaft end, it has proven advantageous if the rotor carrier is centered relative to the shaft end by means of a centering cone, since such a centering cone offers the possibility of improving the centering of the sensor rotor relative to the shaft end and, in particular, compensating for thread play.

[0023] Furthermore, it has proven advantageous if the shaft end coupled to and supporting the sensor rotor is guided in a centered position by a bearing, so that the shaft end itself does not move with significant centering errors and transmit these to the sensor rotor.

[0024] For this purpose, it is particularly advantageous if the shaft end has a maximum distance from the bearing that guides it centrally, which corresponds to a diameter of the shaft end.

[0025] Precise centering of the sensor rotor relative to the axis around which it rotates is therefore advantageous because it allows for a small gap between the sensor rotor and the stator, which in turn promotes the generation of the most accurate sensor signal possible.

[0026] In connection with the previous description of the possibilities for installing the sensor generator in the expansion system, it was only defined that it should rotate at a speed proportional to the rotor of the generator that produces electrical energy.

[0027] One advantageous solution involves arranging the sensor generator in a complete housing of the expansion system.

[0028] This solution has the advantage that the sensor generator can be easily protected and, moreover, arranged in direct coupling to the shaft driving it, so that no shaft penetration through the overall housing is required.

[0029] Within the overall housing, the sensor generator can then be arranged in different parts of the same housing.

[0030] For example, it is conceivable to arrange the sensor generator in an expander housing.

[0031] In this case, it is preferably provided that the sensor generator is coupled to a screw shaft.

[0032] One particularly simple and advantageous solution involves arranging the sensor generator in a generator housing.

[0033] In particular, it is advantageous if the sensor generator is coupled to a generator shaft of the generator producing the electrical energy, so that it can directly detect the rotational speed of the generator shaft.

[0034] One particularly advantageous solution involves the sensor rotor of the sensor generator being coupled to and supported by a shaft end of the generator shaft.

[0035] No further details have yet been provided regarding the installation of the stator in the expansion system.

[0036] One advantageous solution involves holding the stator of the sensor generator stationary on an extension of the overall housing of the expansion system.

[0037] In order to arrange the stator of the sensor generator in a way that is as maintenance-friendly and, if necessary, also easy to retrofit, it is preferably provided that the stator of the sensor generator is held on a housing element, in particular a housing element that can be removed from the overall housing.

[0038] This makes maintenance particularly easy and, if necessary, allows for easy retrofitting of the sensor generator.

[0039] In order to easily transmit the sensor signal to a control system for the expansion plant, it is preferably provided that the housing element is equipped with an electrical connection feedthrough, so that the sensor signal can be easily routed out of the overall housing.

[0040] This means that, for example, the stator can be stationary on an extension of a generator housing, or on an extension of an expander housing, or a bearing housing.

[0041] Regarding the design of the expansion device itself, no further details were provided in connection with the previous description of the individual embodiments.

[0042] One advantageous solution provides that the expansion device has at least one expander screw driven by the expanding working medium, by means of which the generator is driven.

[0043] Furthermore, the invention relates to a system for generating electrical energy from heat, in particular from industrial waste heat, comprising an expansion system operated in a thermodynamic cycle, which advantageously has one or more of the features described above.

[0044] In order to operate the generator in the system according to the invention in such a way that the electrical energy it generates is optimally fed into an electrical supply network, a control unit is preferably provided which controls a circuit of the cycle process as well as a mains switch for connecting the generator to an electrical supply network, which is thus able to operate the expansion system and thus the generator in such a way that the electrical energy is optimally fed into the electrical supply network.

[0045] In particular, the control system is designed to detect the voltage generated by the sensor generator, determine a value for the generator's speed from this voltage, and connect the generator to the electrical supply network by closing the mains switch when the generator's speed results in an alternating voltage whose frequency essentially corresponds to a mains frequency of the electrical supply network.

[0046] This ensures that the control system only establishes a connection between the generator and the electrical supply network when optimal feed-in of the generated electrical energy into the supply network is guaranteed.

[0047] Furthermore, it is preferably provided that the control system regulates the cycle of the cyclic process in such a way that, after establishing the connection to the supply network, the generator converts the heat supplied to the thermodynamic cycle into electrical energy with the highest possible efficiency and feeds this energy into the supply network.

[0048] Furthermore, for safety reasons, the control system is designed to monitor the speed of the generator connected to the power grid and, if the frequency of the generated alternating voltage deviates from the grid frequency, to intervene in the circuit to adjust the speed of the generator.

[0049] Another advantageous solution provides that the control system monitors the speed of the generator coupled to the power grid and then, when the difference between the frequency of the alternating voltage generated by the generator and the grid frequency of the power grid exceeds a threshold, disconnects the generator from the electrical power grid by opening the main switch, thus ensuring that in every possible state of the cycle process no disturbing influences occur on the power grid.

[0050] Another advantageous embodiment provides that, when connecting the generator to the power supply network, the control system connects a set of capacitors in parallel to the stator windings of the generator.

[0051] Such a capacitor set makes it possible to achieve optimal power matching with regard to reactive and active power at the connection between the generator and the supply network.

[0052] In particular, the capacitor bank is designed such that its capacitors are each connected in parallel to the stator windings of the generator.

[0053] To slow down the generator's speed when it is disconnected, another advantageous solution involves the control system maintaining the parallel connection of the stator windings with the capacitor bank when the generator is disconnected from the power supply network, and additionally connecting a resistor bank in parallel to it.

[0054] Such a resistor set is designed in particular such that individual resistors of the same are connected in parallel to the stator windings and the capacitors connected in parallel to them, in order to absorb the current generated by the generator in conjunction with the capacitor set and thereby slow down the generator with regard to its speed.

[0055] Furthermore, to ensure that the generator starts up in connection with the start-up of the cycle process in a simple and as easy a manner as possible, another advantageous embodiment of the solution according to the invention provides that the control for starting the generator isolates it from the capacitor bank and the resistor bank, so that the generator can start up independently and without interference from the generator bank and the resistor bank.

[0056] In a further embodiment of a system according to the invention, it is preferably provided that the generator is coupled to the electrical supply network by means of a converter unit.

[0057] Such a converter unit makes it possible to operate the generator in such a way that it generates electrical energy at a generator frequency that does not necessarily have to match the grid frequency of the supply network in order to be able to feed this electrical energy into the supply network at the grid frequency.

[0058] This means that, in particular, the cycle in which the expansion plant is arranged and operated can be used even more optimally for feeding electrical energy into the supply network.

[0059] Furthermore, the converter unit makes it possible to establish the connection between the generator and the supply network essentially without the occurrence of voltage spikes.

[0060] In particular, it is provided that the converter unit converts the electrical energy generated by the generator at a generator frequency into electrical energy at the grid frequency of the supply network and feeds it into the grid.

[0061] Preferably, the converter unit is provided that the electrical energy of the generator is converted into electrical energy for feeding into the supply network when the generator frequency of the electrical energy lies within an operating frequency range of the converter unit, which extends from a minimum frequency to a maximum frequency.

[0062] This means that with this solution, the converter unit is only used when the generator frequency is within the operating range, and thus the converter unit only converts the electrical energy generated by the generator when it is in the operating frequency range, which is chosen so that a meaningful and effective conversion of the electrical energy generated by the generator into the electrical energy at grid frequency is possible.

[0063] Preferably, the minimum frequency is in the range of 30 to 40 Hz and the maximum frequency is in the range of 60 to 80 Hz.

[0064] In order to operate the generator stably, it is preferably provided that the generator frequency can be preset using the converter unit, meaning that the generator is kept at a specific generator frequency, which ensures sensible and efficient operation of the converter unit without the risk of the generator being operated unstably with regard to its generator frequency and thus the generator frequency varying due to operating fluctuations in the cycle process.

[0065] Furthermore, it is particularly advantageous if the generator frequency can be adapted to the power released by the cycle process at the generator through the interaction of the control unit with the converter unit.

[0066] This means that the control system makes it possible to maintain the generator frequency at a stable value, particularly within the operating frequency range.

[0067] For safety reasons, it is also provided that the control system disconnects the generator from the converter unit if the generator frequency is outside the operating range.

[0068] Another advantageous solution provides that the converter unit has a DC intermediate circuit and a second converter powered by this for generating electrical energy at the mains frequency.

[0069] In principle, the DC intermediate circuit could be supplied by the generator via a rectifier unit.

[0070] However, it is particularly advantageous if the converter unit has a first converter that can be connected to the generator to supply the DC link, since with such a first converter it is possible, on the one hand, to efficiently convert the electrical energy generated at the generator frequency into the DC link, and on the other hand, to keep the generator at the generator frequency, if necessary by temporarily feeding electrical energy into the generator in order to keep it at a defined generator frequency.

[0071] Further features and advantages of the invention are the subject of the following description and the graphic representation of some exemplary embodiments.

[0072] The drawing shows: Fig. 1 a schematic representation of a cycle process of a waste heat recovery plant with an expansion plant; Fig. 2 a longitudinal section through a first embodiment of an expansion plant according to the invention; Fig. 3 a section along line 3-3 through the first embodiment of the expansion plant according to the invention; Fig. 4 an enlarged sectional view of a region A in Fig. 2 ; Fig. 5 a section similar Fig. 3 by a second embodiment of an expansion system according to the invention; Fig. 6 a section similar to Fig. 3 by a third embodiment of an expansion system according to the invention; Fig. 7 an enlarged section similar to Fig. 4 by a fourth embodiment of an expansion position according to the invention; Fig. 8 an enlarged view of a rotor carrier according to the fourth embodiment of the expansion system according to the invention; Fig. 9 a flowchart illustrating the commissioning of the in Fig. 1 Fig. 10 shows the expansion system in connection with the cycle process 10 in which the expansion system is integrated; Fig. 10 shows a partial schematic representation of a fifth embodiment of a system according to the invention with an expansion system; and Fig. 11 shows a similar schematic representation. Fig. 1 a sixth embodiment of a system according to the invention with an expansion system.

[0073] A plant for generating electrical energy from heat, in particular for generating electrical energy from waste heat, comprises a Fig. 1 depicted cycle process, in particular a cycle process operating with a Rankine cycle, in which a working medium guided in a circuit 10 is compressed by a compressor 12, which is driven by a motor 14.

[0074] In a subsequent heat exchanger 16, the working medium is evaporated by supplying heat from a heat stream 18.

[0075] For example, heat is supplied by the heat flow 18 via a hot water circuit 20, which also flows through the heat exchanger 16 and in which a hot water pump 22 is arranged to circulate the hot water in the hot water circuit 20, which in turn is driven by a motor 24.

[0076] The working medium evaporated by the supply of the heat flow 18 in the heat exchanger 16 is supplied to an expansion plant 30 arranged downstream of the heat exchanger 16 in the circuit 10, which includes an expansion device 32 that drives a generator 34 for electricity generation.

[0077] After passing through the expansion device 32, the working medium is fed into the circuit 10 to a heat exchanger 36, in which the working medium condenses, whereby a heat flow 38 is removed through the heat exchanger 36.

[0078] For this purpose, a cold water circuit 40 is provided in particular, which also passes through the heat exchanger 36, wherein a cold water pump 42 is arranged in the cold water circuit 40, which is driven by a motor 44.

[0079] In particular, the compressor 12 performs an isentropic, preferably an ideal isentropic, compression of a liquid saturated condensate of the working medium produced by the heat exchanger 36, and in the heat exchanger 16 an essentially isobaric evaporation of the subcooled system takes place until the vapor saturated state is reached, in which the working medium is then supplied to the expansion system 30, whereby mechanical work is generated in the expansion device 32 by expansion, by which the generator 34 is driven.

[0080] In the heat exchanger 36, an isobaric, in particular a complete isobaric, condensation of the working medium takes place by removing the heat flow 38, so that a liquid saturated condensate can then be supplied to the compressor 12.

[0081] Organic working media such as R245fa, R1224yd(z), R1336mzz(Z), R1336mzz(E), R1233zd, R1234ze, R1234yf, R134a, R513a, R245fa and mixtures thereof or similar media are used.

[0082] Preferably, such a cycle process serves to utilize industrial waste heat, which is generated, for example, in the range between 85°C and 700°C, whereby this waste heat can be optimally converted into electrical energy by the cycle process described above.

[0083] In the Fig. 2 bis 4 A first embodiment of an expansion system 30 used in the circuit 10 described above is shown.

[0084] The expansion device 32 is designed, for example, as a screw expander, which in one embodiment is designed as a single-screw expander, or which in the embodiment shown in the exemplary embodiment has, for example, two interlocking expander screws 52 and 54, which in turn are arranged in screw bores 53, 55 in an expander housing 62 by means of screw shafts 56 and 58 projecting on both sides beyond these and are rotatably mounted about axes of rotation 64 and 66 parallel to each other, wherein, for example, two bearing sets 72 and 74 are provided for the screw shaft 56 and two bearing sets 76 and 78 are provided for the screw shaft 58.

[0085] In this case, for example, the bearing sets 72 and 76 are arranged on the high-pressure side of the expander screws 52 and 54, and the bearing sets 74 and 78 are arranged on the low-pressure side of the expander screws 52 and 54.

[0086] The expansion device 32 is coupled to the generator 34 in such a way that one of the screw shafts, for example the screw shaft 56, is guided into the generator 34 and forms a generator shaft 98, which carries a rotor 82, which in this case is also rotatably mounted about the axis of rotation 64.

[0087] Furthermore, the rotor 82 is surrounded by a stator 84, which is fixedly arranged in a generator housing designated as a whole by 86, wherein this generator housing 86 preferably connects directly to the expander housing 62, for example even being integrally connected to it.

[0088] The generator housing 86 is preferably closed on a side opposite the expander housing 62 by a housing element 88, for example designed as a removable housing cover.

[0089] To improve the running characteristics of the rotor 82, the housing element 88 is provided with a bearing support 92, which extends from the housing element 88, for example as a cylindrical extension 94, towards a shaft end 96 of the generator shaft 98, which is designed in particular as a one-piece extension of the screw shaft 56, and supports the shaft end 96 concentrically to the axis of rotation 64 by means of a bearing 102, in particular in addition to the bearing sets 72 and 74, in order to ensure the smoothest and most precise running possible of the rotor 82 rotating about the axis of rotation 64.

[0090] During the Fig. 2 and 3In the expansion device 32 shown as an example, the pressurized heated working medium coming from the heat exchanger 16 enters an inlet 112 of an overall housing 110 of the expansion system 30 comprising the expander housing 62 and the generator housing 86, then flows through the expansion device 32, in particular the chambers formed with the expander housing 32 by the expander screws 52 and 54, and then, after expansion, enters the generator housing 86, so that the rotor 82 and the stator 84 in the generator housing 86 are cooled by the expanded working medium, and leaves the generator housing 86 through an outlet 114 ( Fig. 2 ).

[0091] Preferably, the outlet 114 is arranged on the generator housing 86 on one side of the generator 34 opposite the expansion device 32.

[0092] To precisely detect the rotational speed of the generator 34, in the first embodiment of the expansion system 30 a speed sensor 120 is assigned to the shaft end 96 of the generator shaft 98, which is preferably arranged in the cylindrical extension 94 of the housing element 88 and faces the shaft end 96, so that the speed sensor 120 is able to detect the rotational speed of the shaft end 96.

[0093] Preferably, the speed sensor 120 is designed as an electrical sensor generator 122, the sensor rotor 124 of which is provided with permanent magnetization, preferably with a magnetization with high field strength, which can be produced, for example, by using rare earth magnets, such as in particular NdFeB or SmCo, which ensure a high permanent field strength.

[0094] For example, the sensor rotor 124 is designed to be multi-pole, in particular four-pole or six-pole.

[0095] Furthermore, the speed sensor 120 comprises a stator 126 surrounding the sensor rotor 124, which carries the stator windings and is itself held coaxially to the axis of rotation 64 and rotationally fixed in the cylindrical extension 94 of the generator housing 86 by a centering element 128.

[0096] It is particularly advantageous for the speed sensor 120 if the sensor rotor 124 is directly coupled to and supported by the shaft end 96.

[0097] In order to guide the sensor rotor 124 of the sensor generator 122 as precisely as possible centered to the axis of rotation 64, the shaft end 96 is located as close as possible to the bearing 102 that guides it centered, in particular at a distance from the bearing 102 that is smaller than a diameter of the shaft end 96.

[0098] For this purpose, a rotor carrier 132 is provided, which carries the sensor rotor 124 and is centered relative to the generator shaft 98 by means of a centering screw 134, which engages with a threaded section 136 in an end thread 138 in the shaft end 96, and is coupled to it in a rotationally fixed manner.

[0099] In order to additionally enable sufficient lubrication of the bearing 102 via a lubricant channel 142 passing through the generator shaft 98, the centering screw 134 is provided with a lubricant channel 144 running coaxially to the lubricant channel 142 and with lubricant channels 146 running radially to the lubricant channel 144, which also extend through the rotor carrier 132 and have outlet openings 148 that allow the lubricant to exit on a side of the shaft end 96 facing away from the rotor 82 near the bearing 102 into the space enclosed by the cylindrical extension 94 and accommodating the speed sensor 120, from which the lubrication of the bearing 102 takes place.

[0100] It follows that the speed sensor 120 is designed to operate reliably and without interference both in a lubricant environment and, if necessary, in the working medium of the circuit 10 carried along by the lubricant.

[0101] In the first illustrated embodiment according to Fig. 4 The stator windings of the stator 126 are contacted via a connecting bushing 152, which is located, for example, in an opening 154 of the housing element 88 and closes it, so that two contacts 156 and 158 located outside the generator housing 86 are available for connecting the stator windings of the stator 126 of the speed sensor 120, which are connected via the connecting bushing 152 to lines 162 and 164 leading to the stator 126 and in particular its stator windings.

[0102] Because the sensor generator 122 forming the speed sensor 120 has a sensor rotor 124 with permanent magnetization, the speed sensor 120 generates as a sensor signal a voltage proportional to the speed of the generator shaft 98, in particular strictly proportional.

[0103] Preferably, the sensor generator 122 with its sensor rotor 124 and stator 126 is designed such that, when the generator 34 generates an alternating voltage with a frequency corresponding to the mains frequency of an electrical supply network 210 supplied by the generator 34, for example at 50 Hz or 60 Hz as a sensor signal, it generates an electrical voltage below 48 V, but preferably in the range between 30 and 48 V, or even better in the range between 40 and 48 V, in order to be able to measure the rotational speed of the generator shaft 98 in the range of the relevant mains frequency as precisely as possible, i.e. by means of a sensor signal with the highest possible voltage, while at the same time avoiding the use of high-voltage components that would have to be used at voltages above 48 V.

[0104] One particularly advantageous embodiment provides that the sensor generator 122 is a standard generator with a permanent magnetized rotor.

[0105] In particular, the voltage generated by the sensor generator 122 can be either an AC voltage or a DC voltage, each of which can be measured directly, i.e. without electrical conversion.

[0106] The solution according to the invention is particularly suitable for use in existing expansion systems 30, if these are constructed in such a way that the housing element 88 of the generator housing 86 has the bearing support 92, in particular designed as a cylindrical extension 94, so that the sensor generator 122 can be subsequently installed in the cylindrical extension by simply removing the housing element 88 into the extension 94.

[0107] Preferably, in the illustrated embodiment, the generator 34 can be connected to a supply network 210 for supplying a large number of consumers by means of a mains switch 206, wherein the supply network is designed for the transmission of an alternating current with a defined stable frequency.

[0108] The voltage is measured by the in Fig. 1 The control unit 200 shown is connected to a measuring input 202 provided for this purpose, which is connected to the speed sensor 120, in particular to the electrical contacts 156 and 158, via a corresponding line.

[0109] The control unit 200 also controls the mains switch 206 via an output 204, which connects an electrical output of the generator 34 to the electrical supply network designated as a whole by 210, so that the generator 34 can feed the generated electrical energy into it.

[0110] Furthermore, the control unit 200 is preferably designed to control the motor 14 of the compressor 12 via an output 212, the motor 24 of the hot water pump 22 via an output 214 and the motor 44 of the cold water pump 42 via an output 216.

[0111] Additionally, it is provided that the control unit 200 controls a switching valve 222 in a bypass line 224 to the expansion device 32 via an output 218.

[0112] In addition, the control unit 200 conveniently has an input 232, via which the state of the electrical supply network 210, in particular with regard to its frequency and voltage, is detected.

[0113] In a second embodiment of the expansion system 30' according to the invention ( Fig. 5 ) those elements which are identical to those of the first embodiment are provided with the same reference numerals, so that with regard to their description reference is made to the explanations of the first embodiment.

[0114] In contrast to the first embodiment, as in Fig. 5 The speed sensor 120', designed as an electric generator 122, is arranged on the side of the bearing set 72 opposite the expander screw 52 on the screw shaft 56, wherein the sensor rotor 124 is coupled to and supported by a shaft end 172, while the stator 126 is stationary in a projection 174 of a bearing housing 176.

[0115] Furthermore, the sensor generator 122 functions in the same way as in the first embodiment and is connected to the control unit 200 in the same way as in the first embodiment.

[0116] In a third embodiment of the expansion system according to the invention 30" ( Fig. 6 ) those elements which are identical to those of the first embodiment are provided with the same reference numerals, so that with regard to their description reference is made to the explanations of the first embodiment.

[0117] In contrast to the first embodiment, as in Fig. 6 The speed sensor 120", designed as an electric generator 122, is arranged on the side of the bearing set 76 opposite the expander screw 54 on the screw shaft 58, wherein the sensor rotor 124 is coupled to and supported by a shaft end 182 of the screw shaft 58, while the stator 126 is stationary in a projection 184 of the bearing housing 176.

[0118] Since the expander screw 54 interacts with the expander screw 52 driving the generator 34, its rotational speed is proportional to the rotational speed of the generator 34, so that the voltage generated by the sensor generator 122 also represents a sensor signal representative of the rotational speed of the generator 34.

[0119] Furthermore, the sensor generator 122 functions in the same way as in the first embodiment and is connected to the control unit 200 in the same way as in the first embodiment.

[0120] In a fourth embodiment of the solution according to the invention, illustrated in Fig. 7 and Fig. 8 , the bearing of the sensor rotor 124 of the sensor generator 122, which operates as a speed sensor 120, is improved and simplified.

[0121] Furthermore, in the fourth embodiment, those parts that are identical to those of the first embodiment are provided with the same reference numerals, so that full reference can be made to the preceding descriptions of the first embodiment.

[0122] In the fourth embodiment, the rotor carrier 132 and the centering screw 134 are combined into a single rotor carrier 192, which can be screwed into the shaft end 96. This rotor carrier directly supports the sensor rotor 124 and, following the threaded section 136, has a centering cone 194 which interacts with a centering cone 286 in the shaft end 96, thus providing additional centering of the rotor carrier 192 relative to the axis of rotation 64 in order to achieve improved centering of the rotor 124. Fig. 7 , 8 ).

[0123] In particular, the combination of the rotor carrier 132 and the centering screw 134 eliminates any play that may occur between them.

[0124] Furthermore, the rotor carrier 192 also includes the lubricant channel 142 running parallel to the axis of rotation 64 and the two lubricant channels 146 running radially to it, with the outlet openings 148, which are arranged in the same way as in the first embodiment ( Fig. 7 , 8 ).

[0125] The commissioning of the above-described embodiments of the expansion systems 30 according to the invention is carried out by the control system 200, for example, according to the instructions in Fig. 9 depicted process.

[0126] In a first step S1, the status of the supply network 210 is continuously checked, in particular with regard to the voltage and frequency in the electrical supply network, recorded at input 232.

[0127] In step S2, the entire components of the circuit 10 and the expansion system 30 are subsequently checked, that is to say in particular the expansion system 30 with the generator 34 and the speed sensor 120.

[0128] In a third step S3, the motor 44 of the cold water pump is switched on to put the cold water circuit 40 into operation and thus ensure the condensation of the working medium in the heat exchanger 36.

[0129] In a further step S4, the switching valve 222 is closed to commission the bypass line 24 for the expansion system 30, so that a significant part of the working medium heated in the heat exchanger 16 does not flow through the expansion system 30, in particular not through the expansion device 32, but through the bypass line 224.

[0130] For example, the proportion of the working medium that flows through the expansion device 32 is less than 10% of the total heated working medium exiting the heat exchanger 16.

[0131] In a further step S5, the motor 24 of the hot water pump 22 is switched on to put the hot water circuit 20 into operation and thus heat the heat exchanger 16 so that evaporation occurs in this working medium.

[0132] Then, in step S6, the motor 14 is switched on to operate the compressor 12, whereby the compressor 12 initially operates at low power to warm up the entire system.

[0133] In the following step S7, the speed of generator 34 is then recorded using the speed sensor 120 in order to determine how quickly generator 34, which in this case operates without load and is driven only by a smaller proportion of the working medium, accelerates.

[0134] In the following step S8, a certain amount of time is waited and the entire system is further warmed up.

[0135] In the following step S9, the switching valve 222 is opened to interrupt the bypass line 224.

[0136] After the bypass line 224 is interrupted, the speed of the generator 34 increases relatively quickly, which is monitored by the speed sensor 120 and after detecting a speed of the generator 34 at which it generates an alternating voltage with a frequency that deviates only slightly from the frequency of the electrical supply network 210 in step S10, the control unit 200 closes the mains switch 206 in step S11, so that the generator 24 now runs under load on the supply network 210 and its speed is stabilized by the supply network 210 itself, so that in the subsequent step S12 the speed of the generator 24 is only monitored as a precaution by means of the speed sensor 120 and the control unit 200.

[0137] Should the speed of generator 34 result in an alternating voltage with a frequency that deviates from the mains frequency by more than a predetermined setpoint, the control unit 200 intervenes in the circuit 10, for example by means of the switching valve 222 activating the bypass line 224 to reduce the speed of generator 34 again or, if necessary, to disconnect generator 34 from the supply network 210 by opening the mains switch 206.

[0138] In a fifth embodiment of a plant according to the invention for generating electrical energy from heat, comprising an expansion plant according to one of the preceding embodiments, those elements that are identical to the preceding elements are provided with the same reference numerals, so that full reference can be made to the descriptions of these elements.

[0139] In contrast to the preceding embodiments, a capacitor set 242 can be connected to the generator 34, which has, for example, capacitors 244, 246, 248 arranged in a delta connection, which can be connected in parallel to individual stator windings 254, 256 and 258 of the generator, with a connecting switch 260 being provided for this purpose, which can be controlled via an output 262 of the control unit 200'.

[0140] In addition, a resistor set 272 can be added to the capacitor set 242, whereby individual resistors 274, 276 and 278 of the resistor set 272 can each be connected in parallel to the capacitors 244, 246, 248.

[0141] For this purpose, a resistance connection switch 280 is provided, which is connected to an output 282 of the control unit 200' and can therefore be controlled by the control unit 200'.

[0142] The fifth embodiment now works such that - as described in connection with the first embodiment - the generator 34 can be switched on with the mains switch 206 when it supplies alternating voltage with a frequency that corresponds to the mains frequency of the supply network 210.

[0143] In addition to connecting the generator 34 to the supply network 210 by means of the mains switch 206, the capacitor set 242 can also be connected in parallel to the stator windings 254, 256 and 258 by means of the connecting switch 260, whereby the capacitor set 242 with its capacitors 244, 246 and 248 serves to make a power adjustment with regard to reactive and active power.

[0144] The control unit 200' then closes the connecting switch 260 when the mains switch 206 is also closed and thus the generator 34 supplies electrical energy to the supply network 210.

[0145] However, if the mains switch 206 is opened, the connecting switch 260 will initially remain closed.

[0146] Additionally, the resistor connection switch 280 is closed by the control unit 200', so that the individual resistors 274, 276 and 278 are now connected in parallel to the capacitors 244, 246 and 248.

[0147] This results in a voltage still being present at the stator windings 254, 256 and 258, and thus, as the rotor 82 of the generator 34 continues to rotate, the rotor 82 is slowed down, since the electrical energy still generated by the generator 34 is converted into heat in the resistors 274, 276 and 278, thus resulting in a slowing down of the rotor 82 of the generator 34.

[0148] As soon as the rotor 82 of the generator 34 comes to a standstill, the resistance connection switch 280 is opened by the control 200' and also the connection switch 260 is opened by the control 200', so that the capacitor set 242 is no longer connected in parallel to the stator windings 254, 256 and 258 of the generator 34.

[0149] When the generator 34 is restarted, the control unit 200' detects the rotational movement of the rotor 82 via the speed sensor 120, whereby - as described above, for example - the speed of the rotor 82 increases by commissioning the circuit 10 and thus also the frequency of the alternating voltage generated by the generator 34 increases.

[0150] During this phase, the stator windings 254, 256 and 258 are not connected to the capacitor set 242.

[0151] Only when the generator 34 is connected to the supply network 210 by the control unit 200' via the mains switch 206, is the capacitor set 242 connected again via the connecting switch 260 in order to carry out the power adjustment as already mentioned above.

[0152] However, the resistor connection switch 280 remains open, and thus the resistor set 272 remains disconnected from the capacitor set 242, until the mains switch 206 is opened again. Only then is the resistor connection switch 280 connected to the capacitor set 242, which causes the previously described braking effect of the rotor 82 of the generator 34.

[0153] In a sixth embodiment of a system according to the invention with an expansion system, illustrated in Fig. 11 The electrical energy generated by the generator 34 is supplied to a converter unit 300 via the mains switch 206. This unit comprises a first converter 302, which supplies the alternating current, in particular the three-phase alternating current generated by the generator 34, to a DC intermediate circuit 304 of the converter unit 300 in the form of direct current.

[0154] This DC intermediate circuit 304 is in turn connected to a second converter 306 of the converter unit 300, which in turn converts the DC current of the DC intermediate circuit 304 and supplies it to an AC output circuit 308 with the mains frequency corresponding to the supply network 210.

[0155] In the AC output circuit 308, a first inductor set 312 and a second inductor set 314 are provided, and a capacitor set 316 is provided between the two inductor sets 312 and 314, so that with the inductor sets 312 and 314 and the capacitor set 316 an optimal adaptation of the alternating current generated by the second converter 306 to the supply network 210 is possible.

[0156] The AC output circuit 308 can also be connected to the supply network 210 via an output switch 322.

[0157] In this sixth embodiment, the control unit 200" is designed such that it connects the generator 34 to the first converter 302 by means of the mains switch 206 only when the generator 34 is rotating at a minimum speed that is detected by the speed sensor 120.

[0158] For example, the minimum speed of generator 34 is dimensioned such that the generated alternating current has a generator frequency that corresponds approximately to a minimum frequency in the range of 20 Hz to 30 Hz.

[0159] From this minimum frequency, an operating frequency range for the first converter 302 is reached, so that direct current is then fed into the DC link 304 from the first converter 302.

[0160] In this operating frequency range, the second converter 306 is therefore also able to generate an alternating current in the alternating current output circuit 308, which has a frequency that corresponds to the mains frequency of the supply network 210.

[0161] The control unit 200" is thus able to control the first converter 302 via an output 342 in such a way that, from the moment the minimum frequency of the alternating current is reached, the first converter 302 operates in such a way that its converter frequency is a few Hz, for example 1 to 3 Hz, lower than the generator frequency, in order to extract energy from the generator 34 by braking it and thereby feed the electrical energy generated by the generator 34 into the DC intermediate circuit 304.

[0162] In contrast, the second converter 306 is always operated in such a way that it generates an alternating current with exactly the mains frequency of the supply network 210 and feeds it into the alternating current output circuit 308.

[0163] The control unit 200' is thus able to operate the generator 34 in a speed range that results in an alternating current which can vary in the operating range between the aforementioned minimum frequency and a maximum frequency, which is, for example, between 60 and 80 Hz, since there is always the possibility of feeding the generated alternating current into the DC intermediate circuit 304 via the first converter 302.

[0164] The control unit 200" will in particular operate the cycle process in such a way that the generator 34 provides the most optimal energy yield possible for feeding into the supply network 210.

[0165] Should problems occur in the supply network 210, the control unit 202' is able to disconnect the second converter 306 from the network by means of the output switch 322 and thus prevent damage to it.

[0166] Likewise, the control unit 200" is able to disconnect the first converter 302 from the generator 34 if its rotational speed leads to generator frequencies of the generated alternating current that are outside the operating range, which extends from the minimum frequency to the maximum frequency.

[0167] The sixth embodiment of the system according to the invention can be operated in a modification of the first embodiment such that steps S1 to S7 are carried out in accordance with Fig. 9 in the same manner by the controller 200" as described in connection with the controller 200.

[0168] However, after a much shorter operating time according to step S8, step S9 can be executed and in step S10, the electrical energy generated at the generator frequency corresponding to the operating frequency range can be fed into the supply network 210 according to step S10.

[0169] Subsequently, the control unit 200" gradually increases the generator frequency within the operating frequency range in order to have the possibility of feeding even more electrical power from generator 34 into the supply network 210.

[0170] In this process, the control unit 200" will, on the one hand, optimize the processes in the cycle so that as much electrical energy as possible is generated at the generator 34 and can be fed into the supply network 210, whereby the first converter 302 is always adjusted to the generator frequency based on the sensor signals of the speed sensor 120, provided that this is within the operating frequency range.

[0171] However, it is also possible to increase the generator frequency only up to a defined frequency, for example the operating frequency corresponding to the mains frequency, using the 200" control unit, and then to maintain it at this frequency.

Claims

1. An expansion installation (30) for obtaining electrical energy from heat by means of a thermodynamic circulation procedure, comprising an expansion device (32), which is operated by an expanding working medium of the thermodynamic circulation procedure, and a generator (34) driven by the expansion device (32), wherein the expansion installation (30) is provided with a rotational speed sensor (120), characterized in that the rotational speed sensor (120) is coupled to a shaft (98, 56, 58) of the expansion installation (30) that rotates proportionally to a rotor (82) of the generator (34), and which takes the form of an electrical sensor generator (122) that generates an electrical sensor signal in that as a sensor signal the electrical sensor generator (122) generates an electrical voltage, and in that the sensor generator (122) is arranged in an overall casing of the expansion installation (30) and is exposed therein to an organic working medium and lubricant.

2. The expansion installation as claimed in claim 1, characterized in that the sensor generator (122) has a permanently magnetized sensor rotor (124) that cooperates with a stator (126) having stator windings, wherein, during rotation of the sensor rotor (124), there is produced at the stator windings of the stator (126) a voltage that is dependent on the speed of the sensor rotor (124) and represents the sensor signal.

3. The expansion installation as claimed in one of the preceding claims, characterized in that, for the purpose of achieving the permanent magnetization, the sensor rotor (124) has a magnet material comprising rare earth elements.

4. The expansion installation as claimed in one of the preceding claims, characterized in that the sensor generator (122) is configured such that, at a speed of rotation of the generator (34) that corresponds to a frequency of the generated AC voltage lying in the range of a grid frequency of a grid, it generates a voltage in the range between 30 V and 48 V, preferably between 40 V and 48 V.

5. The expansion installation as claimed in one of the preceding claims, characterized in that the sensor rotor (124) of the sensor generator (122) is coupled directly and non-rotatably to a shaft end (96, 172, 182) and is carried by it.

6. The expansion installation as claimed in one of the preceding claims, characterized in that the sensor rotor (124) of the sensor generator (122) is arranged on a rotor carrier (162, 192) that is connected to the shaft end (96, 172, 182), in that in particular the rotor carrier (162, 192) is connected to the shaft end (96) by means of a centering screw (134), in that in particular the rotor carrier (192) is centered in relation to the shaft end (96) by means of a centering cone (194).

7. The expansion installation as claimed in one of the preceding claims, characterized in that the shaft end (96, 172, 182) that is coupled to and carries the sensor rotor (124) of the sensor generator (122) is guided in centered manner by a bearing (102, 72, 76), in that in particular the shaft end (96, 172, 182) is at a spacing from the bearing (102, 72, 76) that guides it in centered manner at most by an amount that corresponds to a diameter of the shaft end (96, 172, 182).

8. The expansion installation as claimed in one of the preceding claims, characterized in that the sensor generator (122) is arranged in an overall casing (110) of the expansion installation (30), in that in particular the sensor generator (122) is arranged in an expander casing (62), in that in particular the sensor generator (122) is coupled to a screw shaft (56, 58).

9. The expansion installation as claimed in one of the preceding claims, characterized in that the sensor generator (122) is arranged in a generator casing (86), in that in particular the sensor generator (122) is coupled to a generator shaft (98), in that in particular the sensor rotor (124) of the sensor generator (122) is coupled to a shaft end (96) of the generator shaft and carried by it.

10. The expansion installation as claimed in one of the preceding claims, characterized in that the stator (136) of the sensor generator (120) is held on a casing element (88), in particular a casing element (88) that is demountable from the overall casing (110), in that in particular the casing element (88) is provided with an electrical terminal feedthrough (152).

11. The expansion installation as claimed in one of the preceding claims, characterized in that the stator (126) of the sensor generator (122) is held stationary on a projection (94, 174, 184) of an overall casing (110) of the expansion installation (30).

12. The expansion installation as claimed in one of the preceding claims, characterized in that the expansion device (32) has at least one expander screw (52, 54), which is driven by the expanding working medium and drives the generator (34).

13. An installation for obtaining electrical energy from heat, in particular from waste heat, comprising an expansion installation (30) that is operated in a thermodynamic circulation procedure, characterized in that the expansion installation (30) takes a form as claimed in one of claims 1 to 12, in that in particular this installation has a controller (200), which controls a circuit (10) of the circulation procedure and a power switch (206) for connecting the generator (34) to an electrical grid (210), in that in particular the controller (200) detects the voltage generated by the sensor generator (122), determines therefrom a value of the speed of rotation of the generator (34) and, by closing the power switch (206), connects the generator (34) to the electrical grid (210) when the speed of rotation of the generator (34) gives an AC voltage of which the frequency corresponds to a grid frequency of the electrical grid (210).

14. The installation as claimed in claim 13, characterized in that the controller (200) monitors the speed of rotation of the generator (34) that is coupled to the grid (210) and, if the frequency of the generated AC voltage deviates from the grid frequency, intervenes in the circuit (10) in controlling manner, adapting the speed of the generator (34), in that in particular the controller (200) monitors the speed of rotation of the generator (34) that is coupled to the grid (210) and, if the difference between the frequency of the AC voltage generated by the generator (34) and the grid frequency of the grid (210) exceeds a threshold, isolates the generator (34) from the electrical grid (210) by opening the power switch (206).

15. The installation as claimed in claim 13 or 14, characterized in that the generator (34) is coupled to the electrical grid (210) by means of a converter unit (300), in that in particular the converter unit (300) converts the electrical energy that is generated by the generator (34) at a generator frequency into electrical energy having the grid frequency of the grid (210), and feeds it to the grid (210), in that in particular the converter unit (300) converts the electrical energy of the generator (34) into electrical energy for feeding to the grid (210) if the generator frequency lies in an operating frequency range that extends from a minimum frequency to a high frequency, in that in particular the converter unit (300) is configured to predetermine the generator frequency of the generator (34), in that in particular, as a result of cooperation between the controller (200") and the converter unit (300), the generator frequency is adaptable to the output released by the circulation procedure at the generator (34), in that in particular the controller (200) uncouples the generator (34) from the converter unit (300) if the generator frequency lies outside the operating frequency range, in that in particular the converter unit (300) has a DC link circuit (304) for generating electrical energy at the grid frequency, in that in particular the converter unit (300) has a first converter (302), which is connectable to the generator (34), for feeding the DC link circuit (304).