Device for generating electrical and / or mechanical energy with an ORC system, and method for operating a working fluid circuit of an ORC system

Abstract

The invention relates to a device (100) for generating electrical and / or mechanical energy with an ORC system, which has a working fluid circuit (10) for a working fluid, wherein the working fluid circuit (10) comprises a working fluid evaporator (11), an expansion machine (19) operated with working fluid vapor from the working fluid evaporator (11), and a condenser (12). A source medium flow is permeable to the working fluid evaporator (11) on a primary side (111) to transfer thermal energy contained in the source medium flow to the working fluid and thereby at least partially evaporate the working fluid. The working fluid vapor is supplied to the expansion machine (19) from the working fluid evaporator (11) at a predetermined degree of saturation. The invention further relates to a method for operating a working fluid circuit (12) with an ORC system.

Description

[0001] The invention relates to a device for generating electrical and / or mechanical energy with an ORC system, which has a working fluid circuit for a working fluid, wherein the working fluid circuit comprises a working fluid evaporator and an expansion machine operated with working fluid vapor from the working fluid evaporator. The invention further relates to a method for operating a working fluid circuit of an ORC system.

[0002] An ORC system (ORC = Organic Rankine Cycle) is a system that uses a thermodynamic cycle to generate mechanical and / or electrical energy from heat. An ORC system uses a working fluid cycle that does not employ water as the working fluid, but typically uses organic media such as butane, toluene, silicone oil, or ammonia, which have a lower evaporation temperature than water. The working fluid in an ORC system is usually pumped in its liquid state from a working fluid reservoir to a working fluid evaporator by a feed pump. There, the liquid working fluid is converted into working fluid vapor by the addition of heat, which then enters an expansion machine, which may, for example, be a steam turbine.In the expansion engine, the working fluid is expanded to a lower pressure, generating mechanical energy, and then condensed in a condenser, from which the liquid working fluid returns to the working fluid reservoir. From there, the working fluid is returned to the working fluid evaporator in the recirculation cycle, where it is reheated and evaporated again. It should be noted that media with a higher evaporation temperature than water can also be used as working fluids in an ORC system. ORC systems can be particularly advantageous for generating electrical and / or mechanical energy from heat when the available temperature difference between a heat source and a heat sink is too small to operate a heat engine, such as a turbine, using water as the working fluid.

[0003] ORC systems can be operated not only with heat from combustion plants. The heat required to operate an ORC system can also be obtained geothermalally or from solar power plants. Furthermore, ORC systems can also be operated with the waste heat from internal combustion engines (e.g., reciprocating engines or gas turbines). When utilizing waste heat from internal combustion engines, it is possible to use heat from the flue gas as well as heat from a coolant circuit designed to cool the internal combustion engine.

[0004] The efficiency of ORC systems generally increases with the temperature at which the evaporated working fluid is expanded in the expansion chamber. Efficient operation of ORC systems is particularly possible when the temperature T is high. E of the working fluid vapor at the inlet of the expansion machine in a range of approximately 150 °C ≤ T E≤ 300 °C. It is known that the efficiency of an ORC system can be increased if the working fluid vapor, after expansion in the expansion machine, is passed through a recuperator in which residual heat from the working fluid vapor is transferred to the liquid working fluid supplied to the working fluid evaporator.

[0005] ORC cycles are currently operated with superheating, meaning the working fluid is heated above its saturation temperature in the evaporator. This operating mode is used to ensure that no liquid components of the working fluid enter the expansion engine, which could damage it and reduce its efficiency. In other words, the superheating provides a control buffer, ensuring that the working fluid is supplied to the expansion engine at 100% saturation. Superheating is currently set by a combined measurement of pressure and temperature values ​​downstream of the evaporator. However, the saturation level cannot yet be measured precisely, which is why a (slight) superheat is set, as this is the only way to guarantee that dry vapor (100% saturation) is always present.In practice, for example, an overheating of approximately 5 K has proven effective. Control parameters that influence the overheating include the fill level of the working fluid circuit and the flow rate through the working fluid evaporator. These can be regulated based on pressure and temperature measurements.

[0006] However, operating the ORC cycle with superheating has disadvantages in terms of efficiency, since evaporation tends to occur at a lower pressure level, which leads to a correspondingly lower pressure ratio across the expansion machine and thus reduces the generable mechanical and / or electrical power.

[0007] The object of the invention is therefore to provide a device for generating electrical and / or mechanical energy with an ORC system that has an improved mechanical or electrical efficiency.

[0008] This problem is solved by a device for generating electrical and / or mechanical energy according to claim 1 and a method for operating a working fluid circuit of an ORC system according to claim 12. Advantageous embodiments and further developments of the invention are specified in the dependent claims.

[0009] A first aspect of the present invention relates to a device for generating electrical and / or mechanical energy with an ORC system, which has a working fluid circuit for a working fluid, wherein the working fluid circuit comprises a working fluid evaporator, an expansion machine operated with working fluid vapor from the working fluid evaporator, and a condenser. A source medium flow is present on a primary side of the working fluid evaporator to transfer thermal energy contained in the source medium flow to the working fluid and thereby at least partially evaporate the working fluid. The working fluid vapor is supplied to the expansion machine from the working fluid evaporator at a predetermined degree of saturation.

[0010] The degree of saturation is defined as the quotient of the mass of working fluid vapor in a given volume and the total mass of the working fluid in that given volume. A 100% degree of saturation means that the entire working fluid is in vapor form, while a saturation level of 0% describes a working fluid that is entirely in liquid form.

[0011] Generally speaking, the source medium flow represents the heat source from which the thermodynamic cycle carried out in the working fluid circuit is fed.

[0012] The working fluid can be, in particular, a so-called dry medium, meaning that the Ts diagram of the working fluid shows a positive slope of the saturated vapor curve. The working fluid can be, in particular, methylcyclohexane, pentane, butane, trans-1-chloro-3,3,3-trifluoropropene (R1233zde), ethylbenzene, or (Z)-1,1,1,4,4,4-hexafluoro-2-butene.

[0013] The expansion machine can include a turbine, in particular a steam turbine, or a positive displacement machine.

[0014] The condenser can be subjected to a flow of cooling medium on a secondary side in order to transfer at least some of the heat energy contained in the working fluid to a cooling medium contained in the cooling medium flow and thereby at least partially condense the working fluid.

[0015] The condenser and / or the working fluid evaporator can each include at least one heat exchanger, in particular at least one plate heat exchanger or shell and tube heat exchanger.

[0016] In particular, the device for generating electrical and / or mechanical energy may include a steam saturation sensor arranged downstream of the working fluid evaporator and upstream of the expansion machine in the working fluid circuit and configured to detect a degree of saturation of the working fluid vapor.

[0017] The vapor saturation sensor can detect the degree of saturation directly or indirectly. Indirect detection means that a measurement taken by the vapor saturation sensor can be converted into a degree of saturation. Although the vapor saturation sensor can, in principle, be located at any position between the working fluid outlet of the vaporizer and the working fluid inlet of the expansion machine, positioning it closer to the working fluid outlet of the vaporizer offers the advantage of enabling timely control intervention if a saturation level below a saturation threshold is detected. Conversely, positioning it closer to the working fluid inlet of the expansion machine offers the advantage of allowing for more accurate detection of the saturation level directly at the expansion machine, enabling correspondingly more precise control.

[0018] In some configurations, the vapor saturation sensor can be used in conjunction with additional sensors in the working fluid circuit to measure the pressure and temperature of the working fluid. At least one pressure sensor and one temperature sensor can be positioned, for example, downstream of the working fluid evaporator. This combination enables the reliable measurement of saturation levels (100%) via the vapor saturation sensor and also the detection of any superheating (via the pressure and temperature sensors). This creates a synergistic effect that further maximizes the efficiency of the thermodynamic cycle within the working fluid circuit. For instance, if excessive superheating is detected, the control system can quickly counteract it to approach the optimum efficiency of superheat-free operation as closely as possible.

[0019] In some versions, the steam saturation sensor can be configured to directly measure the degree of saturation. This means, in particular, that the steam saturation sensor outputs a value corresponding to the degree of saturation, for example, in the form of an analog or digital signal.

[0020] Alternatively, the vapor saturation sensor can be designed to measure a volumetric void fraction of the working fluid vapor, from which the degree of saturation can be calculated.

[0021] The volumetric void fraction is defined as the ratio between the space occupied by a vaporous working fluid in a given control volume and the total volume of the working fluid within that control volume. For saturation levels above 50%, there is an approximately linear relationship between the volumetric void fraction and the saturation level. Corresponding regression parameters can be determined through empirical investigations.

[0022] The vapor saturation sensor can be based in particular on an electrical measuring principle, especially a capacitive and / or resistive measuring principle, an optical measuring principle, an acoustic measuring principle, especially ultrasound, and / or a fluid dynamic measuring principle, especially on the basis of a pressure loss.

[0023] The steam saturation sensor now makes it possible, in particular, to operate the cycle in the working fluid circuit at exactly 100% saturation, thus eliminating the need for the control buffer in the form of (slight) superheating that is typical in the prior art. Since evaporation in the working fluid evaporator can be carried out at a higher pressure due to the elimination of superheating, the pressure differential available via the expansion machine increases, which in turn increases the power output of the cycle, while the (heat) energy input remains essentially the same. While a slightly larger amount of (electrical) energy may be required to supply the feed pump for pressure increase upstream of the working fluid evaporator, this is more than compensated for by the increased power output of the expansion machine.

[0024] In a further embodiment, the device can include a working fluid reservoir arranged downstream of the condenser and designed to receive working fluid condensed in the condenser. The working fluid reservoir can also be referred to as a "hotwell." The working fluid reservoir serves as an intermediate storage for liquid working fluid before it is (re)introduced into the thermodynamic cycle carried out in the working fluid circuit.

[0025] Furthermore, the device can include a feed pump for conveying liquid working fluid into the working fluid evaporator, in particular wherein the feed pump is arranged downstream of the working fluid reservoir. Alternatively or additionally, a suction side of the feed pump can communicate fluidically with a reservoir for liquid working fluid formed in the working fluid reservoir.

[0026] The feed pump is designed to increase the pressure of the working fluid, in particular up to the operating pressure of the working fluid evaporator. Any working fluid conveying device suitable to a person skilled in the art in the art within the context of the present invention can be considered as the feed pump, provided it is suitable for both the desired pressure increase and the desired working fluid flow rate. For example, the feed pump can be a radially or semi-axially flowing centrifugal pump, particularly a variable-speed pump, or a piston pump. The feed pump can include a drive motor, for example, an electric motor.

[0027] According to a preferred embodiment, the device can include a control unit configured to regulate the degree of saturation. In particular, the control unit is configured to receive saturation degree measurements from the steam saturation sensor, and, depending on the saturation degree measurements, a manipulated variable for regulating the degree of saturation can be varied by the control unit in order to adjust the saturation degree to the predetermined level.

[0028] The control device can, for example, include a programmable logic controller with at least one signal input and at least one signal output, in which a program for controlling the degree of saturation can be executed.

[0029] The control variable for regulating the degree of saturation can, in particular, comprise a working fluid volume flow rate through the working fluid evaporator, especially a time-dependent delivery rate of the feed pump. Preferably, the control variable comprises a speed of the feed pump.

[0030] In various designs, the predetermined saturation level, to which the control device adjusts the actual saturation level, can be between 95% and 100%. Preferably, the predetermined saturation level is exactly 100%, as this achieves optimal efficiency. However, smaller liquid quantities up to 5% are generally acceptable at the working fluid inlet of the expansion machine, especially if the working fluid is a dry medium.

[0031] The following is a rough estimate of a possible increase in the performance of the expansion machine using methylcyclohexane as the working fluid.

[0032] In a state-of-the-art cycle operated with a 5 K superheat, the working fluid is evaporated in the evaporator at 240 °C and a pressure of 16.1 bar, and expanded in the expansion engine at a pressure of 0.2 bar. This results in an enthalpy difference of 161.49 kJ / kg, which, assuming an exemplary mass flow rate of 1 kg / s and an expansion engine efficiency of 75%, corresponds to a mechanical power output of 121.116 kW for the expansion engine.

[0033] If, on the other hand, the working fluid is evaporated at 245 °C, which corresponds to a pressure of 17.3 bar, a specific enthalpy difference of 162.26 kJ / kg results, which, assuming an exemplary mass flow rate of 1 kg / s and taking into account an efficiency of the expansion machine of 75%, corresponds to a mechanical power of the expansion machine of 121.695 kW.

[0034] It is therefore evident that the targeted control provided for according to the invention, based on the predetermined saturation level, can achieve a significant increase in turbine performance and consequently also an increase in the thermal efficiency of the cycle. In the above calculation example, the increase in performance is approximately 0.5 percentage points.

[0035] According to a further embodiment, the source medium flow can comprise a fluid, in particular a gaseous fluid, especially an exhaust gas flow from an industrial process and / or an internal combustion engine. The exhaust gas flow can, for example, be a flue gas flow from a combined heat and power plant, for example comprising a piston engine or a gas turbine. The working fluid evaporator can, in particular, be arranged in an exhaust gas stream of the combined heat and power plant.

[0036] However, in some configurations the source medium flow can also include a liquid fluid, in particular water or oil or a mixture of water or oil with another fluid.

[0037] Alternatively or additionally, the cooling medium flow through the condenser on a secondary side can comprise a fluid, in particular a liquid fluid, especially water or a mixture of water with another fluid. However, cooling medium flows comprising a gaseous fluid, such as air or another, particularly non-toxic, gas, are also suitable. Preferably, the cooling medium flow can be part of or coupled into a useful heat circuit. The useful heat circuit can, for example, be a heating circuit. This advantageously ensures that the heat extracted from the working fluid in the condenser and at least partially transferred to the cooling medium of the cooling medium flow is not simply released unproductively into the environment, but can be used energetically in a downstream process.

[0038] According to an additional development, the device can have a recuperator that is permeable on a recuperator primary side by working fluid vapor from the expansion machine and on a recuperator secondary side by liquid working fluid before the liquid working fluid is supplied to the working fluid evaporator.

[0039] Finally, according to a further preferred embodiment, the device can include a vapor saturation sensor arranged downstream of the working fluid evaporator and upstream of the expansion machine in the working fluid circuit and configured to detect the degree of saturation of the working fluid vapor. The vapor saturation sensor is configured for a direct measurement of the degree of saturation or for measuring a volumetric void fraction of the working fluid vapor, from which the degree of saturation can be calculated.The device comprises a control unit configured to regulate the degree of saturation and further configured to receive saturation level measurements from the steam saturation sensor. Depending on these saturation level measurements, a manipulated variable for regulating the degree of saturation can be adjusted by the control unit to maintain the saturation level at a predetermined level of 95% to 100%. This manipulated variable includes a working fluid volume flow rate through the working fluid evaporator, in particular a time-dependent delivery rate of a feed pump.

[0040] The device according to this embodiment allows, in a further improved manner, an optimal efficiency of the thermodynamic cycle carried out in the working fluid circuit to be achieved.

[0041] A second aspect of the present invention relates to a method for operating a working fluid circuit of an ORC plant, in which liquid working fluid is evaporated in a working fluid evaporator by absorbing heat from a source medium stream and is supplied as working fluid vapor with a predetermined degree of saturation to an expansion machine in which the working fluid is expanded, and in which working fluid vapor from the expansion machine is condensed in a condenser by removing heat to a cooling medium of a cooling medium stream.

[0042] The saturation level of the working fluid vapor can be measured at a position in the working fluid circuit downstream of the working fluid evaporator and upstream of the expansion machine using a vapor saturation sensor. Furthermore, a control variable for regulating the saturation level can be varied depending on the saturation level measurements provided by the vapor saturation sensor in order to adjust the saturation level to the predetermined level.

[0043] The control variable for the degree of saturation can include a working fluid volume flow rate through the working fluid evaporator, in particular a time-dependent delivery rate of a feed pump. For example, when saturation level readings are less than 100%, especially less than 95%, the working fluid volume flow rate through the working fluid evaporator can be reduced, and / or when saturation level readings are equal to 100%, the working fluid volume flow rate through the working fluid evaporator can be increased.

[0044] In some embodiments of the method, the steam saturation sensor can directly detect the degree of saturation. In other embodiments, the steam saturation sensor can detect a volumetric void fraction of the working fluid vapor, wherein the volumetric void fraction can be converted into a degree of saturation according to a predetermined calculation rule, in particular wherein the predetermined calculation rule includes at least a piecewise linear relationship between the volumetric void fraction and the degree of saturation.

[0045] Finally, the working fluid vapor can be supplied to the expansion machine essentially without superheating or with a superheat of max. 3 K, in particular max. 2 K, and / or with a predetermined saturation level between 95% and 100%, in particular exactly 100%. By operating the cycle within the working fluid circuit under these parameters, the highest possible efficiency can be achieved, and damage to the expansion machine caused by excessive liquid content in the working fluid vapor is effectively prevented.

[0046] All features, combinations of features and their specific advantages disclosed with respect to the device according to the first aspect of the invention are transferable to the method according to the second aspect of the invention and vice versa.

[0047] Advantageous embodiments of the invention are shown in the drawings and are described below.

[0048] They show: Fig. 1 a system diagram of a device according to the invention for generating electrical and / or mechanical energy with an ORC system according to a first embodiment; Fig. 2 a system diagram of a device according to the invention for generating electrical and / or mechanical energy with an ORC system according to a second embodiment; Fig. 3 a system diagram of a device according to the invention for generating electrical and / or mechanical energy with an ORC system according to a third embodiment and Fig. 4 a TS diagram of a section of the thermodynamic cycle carried out in the working fluid circuit of the ORC system of the device according to the invention and a comparison process according to the prior art.

[0049] The one in Fig. The device 100 shown in Figure 1 for generating electrical and / or mechanical energy comprises an ORC system with a working fluid circuit 10 for a working fluid, in which a working fluid evaporator 11 for evaporating the working fluid, an expansion machine 19, in particular in the form of a steam turbine, and a condenser 12 are arranged. The condenser 12 serves to condense working fluid vapor, in particular saturated working fluid steam, into liquid working fluid.

[0050] The working fluid can be, in particular, a so-called dry medium, meaning that the Ts diagram of the working fluid shows a positive slope of the saturated vapor curve. The working fluid can be, in particular, methylcyclohexane, pentane, butane, or trans-1-chloro-3,3,3-trifluoropropene (R1233zde). Alternatively, the working fluid can be ethylbenzene. However, it is also possible to use butane, toluene, silicone oil, or ammonia as the working fluid in the cycle.

[0051] To generate electrical energy, the expansion machine 19 is coupled to an electrical generator G.

[0052] The thermodynamic cycle carried out in the working fluid circuit 10 begins with the feed pump 15, which compresses liquid working fluid to the operating pressure of the working fluid evaporator 11. The pressure side 152 of the feed pump 15 is fluidically connected to a working fluid inlet 112' of the working fluid evaporator secondary side 112.

[0053] The working fluid evaporator 11 has a working fluid evaporator primary side 111, through which a source medium flows, serving as a heat source for the thermodynamic cycle carried out in the working fluid circuit 10. The working fluid evaporator primary side 111 has a source medium inlet 111' and a source medium outlet 111".

[0054] The working fluid flows on the secondary side 112 of the working fluid evaporator 11, and heat is supplied to it from the source medium stream to vaporize it. The secondary side 112 of the working fluid evaporator has a working fluid inlet 112' and a working fluid outlet 112". Liquid working fluid from the feed pump 15 is fed to the working fluid inlet 112'. The working fluid, vaporized in the working fluid evaporator 11, is directed through the working fluid outlet 112" of the secondary side 112 of the working fluid evaporator to the expansion machine 19.

[0055] The source medium flow can be supplied at the source medium inlet 111' of the working fluid evaporator primary side 111, for example, at a temperature T. Q_V_ein enter the working fluid evaporator 11 at 500 °C and with an output temperature T Q_V_ausThe source medium flow exits the working fluid evaporator 11 at a temperature of 200 °C at the source medium outlet 111" of the primary side 111. The source medium flow comprises, in particular, a gaseous fluid, especially an exhaust gas flow from an industrial process and / or an internal combustion engine.

[0056] In the working fluid circuit 10, a vapor saturation sensor 13 is arranged between the working fluid outlet 112" of the working fluid evaporator secondary side 112 and an inlet of the expansion machine 19. This sensor is designed to detect the degree of saturation of the working fluid vapor. The vapor saturation sensor 13 can detect the degree of saturation directly or indirectly. Indirect detection means that a measured value detected by the vapor saturation sensor can be converted into a degree of saturation. Saturation degree measurements detected by the vapor saturation sensor 13 can be used to control process parameters of the thermodynamic cycle carried out in the working fluid circuit 10.In particular, this makes it possible to provide the working fluid vapor of the expansion machine 19 essentially without overheating and yet to ensure that a sufficiently high degree of saturation, for example 95% to 100%, in particular exactly 100%, is present.

[0057] As the working fluid vapor passes through the expansion machine 19, it expands and is then directed into the condenser 12. Here, heat is extracted from the working fluid vapor flowing on a primary side 122 of the condenser, leading to at least partial condensation of the working fluid. A cooling medium flows on a secondary side 121 of the condenser, absorbing the heat from the working fluid. The cooling medium flow is fed to the secondary side 121 of the condenser at a cooling medium inlet 121' and discharged at a cooling medium outlet 121". The cooling medium flow can be part of a useful heat circuit, in particular a heating circuit, for example, a district heating network or a building heating system. The cooling medium can be supplied at 60 °C (useful heat circuit return) at the cooling medium inlet 121' of the secondary side 121 of the condenser. This corresponds to the inlet temperature T. KM_K_einof the cooling medium into the condenser 12. The cooling medium can enter the condenser 12 at the cooling medium outlet 121" of the condenser secondary side 121 with an output temperature T. KM_K_aus leave, for example, 80 °C.

[0058] The working fluid condensed on the primary side 122 of the capacitor is then fed in liquid form to the suction side 151 of the feed pump 15, so that the cycle can begin again.

[0059] In Fig. Figure 2 shows a device 100 according to the invention for generating electrical and / or mechanical energy according to a second embodiment. Since the device 100 according to the second embodiment largely corresponds to the device 100 according to the first embodiment, only the differences will be discussed.

[0060] The pressure side 152 of the feed pump 15 is fluidically connected to a working fluid inlet 162' of a recuperator secondary side 162 of a recuperator 16. The function of the recuperator 16 will be explained later. After passing through the recuperator 16, the working fluid leaves the recuperator 16 at a working fluid outlet 162" of the recuperator secondary side 162.

[0061] As the working fluid vapor passes through the expansion machine 19, it expands and enters a working fluid inlet 161' onto a recuperator primary side 161 of the recuperator 16. In the recuperator 16, heat is transferred from the working fluid vapor on the recuperator primary side 161 to liquid working fluid on the recuperator secondary side 162. This preheats the liquid working fluid before it flows into the working fluid evaporator 11, thus increasing the mechanical and / or electrical efficiency of the device 100.

[0062] After the recuperator 16, the working fluid, which is still at least partially present in the form of working fluid vapor, flows from a working fluid outlet 161" of the recuperator primary side 161 into the condenser 12.

[0063] The working fluid condensed on the primary side 122 of the condenser is then fed in liquid form to a working fluid reservoir 14, which may be located below the condenser 12, particularly with respect to gravity. The working fluid condensate is fed to the working fluid reservoir 14, in particular via a working fluid inlet 141, and discharged from the working fluid reservoir 14 via a working fluid outlet 142. The working fluid reservoir 14 serves, in effect, as an intermediate storage tank for liquid working fluid before it is reintroduced into the thermodynamic cycle. The working fluid outlet 142 of the working fluid reservoir 14 is fluidically connected to a suction side 151 of the feed pump 15.

[0064] In Fig. Figure 3 shows a device 100 according to the invention for generating electrical and / or mechanical energy according to a third embodiment. Since the device 100 according to the third embodiment largely corresponds to the device 100 according to the second embodiment, only the differences will be discussed.

[0065] The device 100 has a control unit 17, which is configured to regulate the degree of saturation. The control unit 17 receives saturation degree measurements from the steam saturation sensor 13 via a signal input 172. Depending on the saturation degree measurements, the control unit 17 can vary a manipulated variable to regulate the degree of saturation in order to adjust the saturation degree to the predetermined saturation level.

[0066] The manipulated variable is output via a signal output 171, which is operationally connected to the feed pump 15. The manipulated variable can, in particular, comprise a working fluid volume flow rate through the working fluid evaporator 11, especially a time-dependent delivery rate of the feed pump 15. Preferably, the manipulated variable comprises a rotational speed of the feed pump 15.

[0067] The control device 17 can, for example, comprise a programmable logic controller (PLC) in which a program for controlling the saturation level can be executed. In particular, the control device 17 can include at least one microprocessor.

[0068] In various embodiments, the predetermined saturation level, to which the control device adjusts the actual saturation level, can be between 95% and 100%. Preferably, the predetermined saturation level is exactly 100%, as this achieves the optimal efficiency.

[0069] In Fig. Figure 4 shows a TS diagram of a section of the thermodynamic cycle carried out in the working fluid circuit 10 of the device 100 according to the invention and a comparison process according to the prior art. The working fluid is methylcyclohexane. The cycle is not shown in its entirety, but only the isobaric heat input (in the evaporator) and the expansion in the turbine. In the diagram, the x-axis represents entropy (unit kJ / kg·K) and the y-axis represents temperature (unit °C).

[0070] The state-of-the-art process includes the following steps: from: Temperature increase sensible heat in the working fluid evaporator 11 bf: Heat input latent heat (enthalpy of vaporization) in the working fluid evaporator 11 fg: Overheating in the working fluid evaporator 11 gh: Relaxation in expansion machine 19

[0071] The working fluid is supplied to the working fluid evaporator 11 at a pressure of approximately 16 bar, with the pressure being generated by the feed pump 15. The compression step is not shown in the diagram.

[0072] The process, which is carried out in the working fluid circuit 10 of the ORC system of the device 100 according to the invention, comprises the steps ade: AC: Temperature increase sensible heat in the working fluid evaporator 11 cd: Heat input latent heat (enthalpy of vaporization) in the working fluid evaporator 11 de: Relaxation in expansion machine 19

[0073] The working fluid is supplied to the working fluid evaporator 11 at a pressure of approximately 17 bar, with the pressure being generated by the feed pump 15. The compression step is not shown in the diagram.

[0074] The final temperature after the working fluid evaporator 11 is 245 °C in both the prior art process and the process carried out in the working fluid circuit 10 of the ORC system of the device 100 according to the invention. However, in the prior art process, saturated steam is first generated at 240 °C, which is then superheated by 5 K. The process carried out in the working fluid circuit 10 of the ORC system of the device 100 according to the invention does not involve superheating and evaporates at a higher pressure (approximately 17 bar).Due to the different positions of points e (process of the working medium circuit of the device according to the invention) and h (process according to the prior art), which describe the state of the working medium after expansion in the expansion machine, it is evident that the process carried out in the working medium circuit 10 of the ORC system of the device 100 according to the invention generates a higher performance than the process according to the prior art. Reference symbol list 100 Device for generating electrical and / or mechanical energy 10 Work equipment cycle 11 Work fluid evaporators 111 Working fluid evaporator primary side 111' Source medium inlet 111" Source medium outlet 112 Working fluid evaporator secondary side 112' Equipment Inlet 112" Tool outlet 12 Capacitor 121 Capacitor secondary side 121' Cooling medium inlet 121" cooling medium outlet 122 Capacitor primary side 13 Steam saturation sensor 14 tool containers 141 Work equipment entry 142 Equipment outlet 15 Feed pump 151 Suction side 152 printed page 16 Recuperator 161 Recuperator primary side 161' Equipment Inlet 161" Tool outlet 162 Recuperator secondary side 162' Equipment Inlet 162" Tool outlet 17 Control unit 171 Signal output 172 Signal input 19 Expansion machine G Generator T Q_V_ein Inlet temperature of source medium flow into working fluid evaporator T Q_V_aus Output temperature of source medium flow from working fluid evaporator T KM_K_einInlet temperature of cooling medium to condenser T KM_K_aus Output temperature of cooling medium from condenser

Claims

[1] Device (100) for generating electrical and / or mechanical energy with an ORC system comprising a working fluid circuit (10) for a working fluid, wherein the working fluid circuit (10) comprises a working fluid evaporator (11) as well as an expansion machine (19) operated with working fluid vapor from the working fluid evaporator (11) and a condenser (12), wherein the working fluid evaporator (11) is permeable on a working fluid evaporator primary side (111) by a source medium flow in order to transfer heat energy contained in the source medium flow to the working fluid and thereby at least partially evaporate the working fluid, wherein the working fluid vapor of the expansion machine (19) is supplied from the working fluid evaporator (11) with a predetermined degree of saturation. [2] Device (100) according to claim 1, comprising a vapor saturation sensor (13) arranged downstream of the working fluid evaporator (11) and upstream of the expansion machine (19) in the working fluid circuit (10) and configured to detect a degree of saturation of the working fluid vapor. [3] Device (100) according to claim 2, wherein the vapor saturation sensor (13) is configured to directly measure the degree of saturation. [4] Device (100) according to claim 2, wherein the vapor saturation sensor (13) is designed to measure a volumetric void fraction of the working fluid vapor, and wherein the degree of saturation can be calculated from the volumetric void fraction. [5] Device (100) according to one of claims 2 to 4, wherein the vapor saturation sensor (13) is based on an electrical measuring principle, in particular a capacitive and / or resistive measuring principle, optical measuring principle, acoustic measuring principle, in particular ultrasound, and / or fluid dynamic measuring principle, in particular on the basis of a pressure loss. [6] Device (100) according to one of the preceding claims, comprising a working fluid collection container (14) arranged downstream of the capacitor (12) and designed to receive working fluid condensed in the capacitor (12). [7] Device (100) according to one of the preceding claims, comprising a feed pump (15) for conveying liquid working fluid into the working fluid evaporator (11), in particular wherein the feed pump (15) is arranged downstream of the working fluid collection container (14) and / or a suction side (151) of the feed pump (15) communicates fluidically with a reservoir for liquid working fluid formed in the working fluid container (14). [8] Device (100) according to one of claims 2 to 7, comprising a control device (17) which is configured to control the degree of saturation and which is further configured to receive saturation degree measurement values ​​from the steam saturation sensor (13), wherein, depending on the saturation degree measurement values, a control variable for controlling the degree of saturation can be varied by the control device (17) in order to adjust the degree of saturation to the predetermined degree of saturation. [9] Device (100) according to claim 8, wherein the control variable comprises a working fluid volume flow through the working fluid evaporator (11), in particular wherein the control variable comprises a time-related delivery rate of the feed pump (15). [10] Device (100) according to one of the preceding claims, wherein the predetermined degree of saturation is between 95% and 100%. [11] Device (100) according to claim 1, comprising a vapor saturation sensor (13) arranged downstream of the working fluid evaporator (11) and upstream of the expansion machine (19) in the working fluid circuit (10) and configured to detect a degree of saturation of the working fluid vapor, wherein the vapor saturation sensor (13) is configured for a direct measurement of the degree of saturation or is designed for measuring a volumetric void fraction of the working fluid vapor, and wherein the degree of saturation can be calculated from the volumetric void fraction, and comprising a control device (17) configured to control the degree of saturation and further configured to receive saturation degree measurements from the steam saturation sensor (13), wherein, depending on the saturation degree measurements, a control variable for controlling the degree of saturation can be varied by the control device (17) in order to adjust the degree of saturation to the predetermined degree of saturation, wherein the manipulated variable comprises a working fluid volume flow through the working fluid evaporator (11), in particular wherein the manipulated variable comprises a time-related delivery rate of a feed pump (15), wherein the predetermined degree of saturation is between 95% and 100%. [12] Method for operating a working fluid circuit (10) of an ORC plant, in which liquid working fluid is evaporated in a working fluid evaporator (11) by absorbing heat from a source medium stream and is supplied as working fluid vapor with a predetermined degree of saturation to an expansion machine (19) in which the working fluid is expanded, and in which working fluid vapor from the expansion machine (19) is condensed in a condenser (12) by removing heat to a cooling medium of a cooling medium stream. [13] Method according to claim 12, - wherein a degree of saturation of the working fluid vapor is detected at a position in the working fluid circuit (10) downstream of the working fluid evaporator (11) and upstream of the expansion machine (19) using a vapor saturation sensor (13), - and wherein a control variable for regulating the degree of saturation is varied depending on the degree of saturation measured values ​​provided by the steam saturation sensor (13) in order to adjust the degree of saturation to the predetermined degree of saturation. [14] Method according to claim 13, - wherein the control variable for regulating the degree of saturation comprises a working fluid volume flow through the working fluid evaporator (11), in particular wherein the control variable comprises a time-related delivery rate of a feed pump (15), - in particular, where the working fluid volume flow through the working fluid evaporator (11) is reduced when saturation level measurements are less than 100%, especially less than 95%, and / or where saturation level measurements are equal to 100%, the working fluid volume flow through the working fluid evaporator (11) is increased. [15] Method according to claim 13 or 14, wherein the vapor saturation sensor (13) directly detects the degree of saturation. [16] Method according to claim 13 or 14, wherein the vapor saturation sensor (13) detects a volumetric void fraction of the working fluid vapor, and wherein the volumetric void fraction is converted into a degree of saturation according to a predetermined calculation rule, in particular wherein the predetermined calculation rule comprises an at least section-by-section linear relationship between the volumetric void fraction and the degree of saturation. [17] Method according to any one of claims 12 to 16, wherein the working fluid vapor is supplied to the expansion machine (19) substantially without superheating or with a superheat of max. 3 K, in particular max. 2 K, and / or with a predetermined degree of saturation between 95% and 100%.

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