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

Abstract

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

Description

[0001] 20.08.2025 u - 1 - Device for generating electrical and / or mechanical energy with an ORC system, and method for operating a working fluid circuit of an ORC system. Description: 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. Furthermore, the invention relates to a method for operating a working fluid circuit of an ORC system. An ORC system (ORC = Organic Rankine Cycle) is understood to be a system that generates mechanical and / or electrical energy from heat using a thermodynamic cycle.In an ORC system, there is a working fluid cycle that does not use water as the working fluid, but typically uses organic media such as butane, toluene, silicone oil, or ammonia, which have a lower evaporation temperature compared to 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 means of a feed pump. There, the liquid working fluid is converted into working fluid vapor by the addition of heat, which then enters an expansion engine, which can be, for example, a steam turbine. In the expansion engine, the working fluid is expanded to a lower pressure while generating mechanical energy and is then condensed in a condenser, from which the liquid working fluid returns to the working fluid reservoir.From this, the working fluid is then fed back into the working fluid evaporator in the working fluid 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 low to operate a heat engine, such as a turbine, using water as the working fluid. ORC systems can be operated not only with heat from combustion plants. The heat required to operate an ORC system can also be obtained from other sources or from solar power plants. Furthermore, ORC systems can also be operated with the waste heat from internal combustion engines (e.g.,...ORC systems are operated by 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 intended for cooling the internal combustion engine. The efficiency of ORC systems generally increases with the temperature at which the vaporized working fluid is expanded in the expansion machine. Efficient operation of ORC systems is particularly possible when the temperature T. E of the working fluid vapor at the inlet of the expansion machine in a range of approx. 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 engine, 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. ORC cycles have so far been operated with superheating, i.e., the working fluid is heated above its saturation temperature in the working fluid 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 corresponding control buffer, ensuring that the working fluid is supplied to the expansion engine at a 100% saturation level.Superheating is currently adjusted by a combined measurement of pressure and temperature values ​​downstream of the working fluid evaporator. However, the degree of saturation cannot yet be measured precisely, which is why a (slight) superheat is set, as this is the only way to ensure that dry steam (100% saturation) is always present. In practice, a superheat of approximately 5 K has proven effective. Control parameters that influence superheating include the fill level of the working fluid circuit and the flow rate through the working fluid evaporator. These can be regulated based on the pressure and temperature measurements.However, operating the ORC cycle with superheating has disadvantages with regard to 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. The object of the invention is therefore to provide a device for generating electrical and / or mechanical energy with an ORC system that exhibits improved mechanical and / or electrical efficiency. This object is achieved 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.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 permeable to the working fluid evaporator on a primary side in order 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.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. 100% saturation means that the entire working fluid is in vapor form, while a saturation of 0% describes a working fluid that is entirely in liquid form. Generally speaking, the source medium flow represents the heat source that feeds the thermodynamic cycle carried out in the working fluid circuit. 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.The expansion machine can comprise a turbine, in particular a steam turbine, or a positive displacement machine. A cooling medium flow can pass through the condenser on a secondary side to transfer at least some of the heat energy contained in the working fluid to a cooling medium contained in the cooling medium flow, thereby at least partially condensing the working fluid. The condenser and / or the working fluid evaporator can each comprise at least one heat exchanger, in particular at least one plate heat exchanger or shell and tube heat exchanger. In particular, the device for generating electrical and / or mechanical energy can comprise a vapor saturation sensor, which is arranged downstream of the working fluid evaporator and upstream of the expansion machine in the working fluid circuit and is configured to detect the degree of saturation of the working fluid vapor.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 a working fluid outlet of the working fluid evaporator and a working fluid inlet of the expansion machine, positioning it closer to the working fluid outlet of the evaporator 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 detecting the degree of saturation directly at the expansion machine with greater accuracy and allowing for correspondingly more precise control.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 and one temperature sensor can be positioned, for example, downstream of the working fluid evaporator. This combination allows for the reliable measurement of saturation levels (100%) via the vapor saturation sensor and also enables 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 example, if excessive overheating is detected, the control system can quickly counteract it to approach the efficiency optimum of overheat-free operation as closely as possible. In some configurations, the steam saturation sensor can be set up 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. Alternatively, the steam saturation sensor can be designed to measure the volumetric void fraction of the working fluid vapor, from which the degree of saturation can be calculated. The volumetric void fraction is defined as the ratio between the space occupied by the vaporous working fluid in a specific control volume and the total volume of the working fluid within the 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. The vapor saturation sensor can be based on an electrical measuring principle, particularly a capacitive and / or resistive measuring principle, an optical measuring principle, an acoustic measuring principle, particularly ultrasound, and / or a fluid dynamic measuring principle, particularly based on pressure loss. The vapor saturation sensor makes it possible, in particular, to operate the cycle in the working fluid circuit with exactly 100% saturation and thereby eliminate the need for the control-related buffer in the form of (slight) superheating that is common in the prior art.Since evaporation can occur at a higher pressure by eliminating superheating in the working fluid evaporator, the pressure differential available via the expansion engine increases. This, in turn, increases the power output of the cycle, while the input (heat) energy 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 engine. In a further embodiment, the device can include a working fluid reservoir located downstream of the condenser and designed to collect working fluid condensed in the condenser. This working fluid reservoir can also be referred to as a "hotwell."The working fluid reservoir serves as an intermediate storage tank for liquid working fluid before it is (re)introduced into the thermodynamic cycle carried out in the working fluid circuit. 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. The feed pump is configured to increase the pressure of the working fluid, in particular up to the operating pressure of the working fluid evaporator.Any feed pump suitable to a person skilled in the art in the art within the context of the present invention can be considered, 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 one with variable speed, or a piston pump. The feed pump can include a drive motor, such as an electric motor. According to a preferred embodiment, the device can include a control unit configured to regulate the degree of saturation.The control device is specifically designed to receive saturation level measurements from the steam saturation sensor. Depending on these saturation level measurements, a manipulated variable for controlling the saturation level can be adjusted by the control device to regulate the saturation level to the predetermined level. The control device can, for example, comprise a programmable logic controller (PLC) with at least one signal input and at least one signal output, in which a program for controlling the saturation level can be executed. The manipulated variable for controlling the saturation level 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 manipulated variable comprises a rotational speed of the feed pump.In various embodiments, the predetermined degree of saturation, to which the control device adjusts the actual degree of saturation, can lie between 95% and 100%. Preferably, the predetermined degree of saturation is exactly 100%, as this achieves the 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. The following is a rough estimate of a possible increase in the expansion machine's performance using methylcyclohexane as the working fluid. In a state-of-the-art cycle operated with a 5 K superheat, the working fluid is evaporated in the working fluid evaporator at 240 °C and a pressure of 16.1 bar, and expansion takes place in the expansion machine 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 machine efficiency of 75%, corresponds to a mechanical power output of 121.116 kW. If, however, the working fluid is evaporated at 245 °C in the evaporator, corresponding to a pressure of 17.3 bar, the specific enthalpy difference is 162.26 kJ / kg, which, assuming an exemplary mass flow rate of 1 kg / s and an expansion machine efficiency of 75%, corresponds to a mechanical power output of 121.695 kW. It is therefore evident that the targeted control provided for according to the invention, based on the predetermined degree of saturation, can achieve a significant increase in the turbine's power output and consequently also an increase in the thermal efficiency of the cycle. In the aboveIn a calculation example, the performance increase is approximately 0.5 percentage points. 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. In embodiments, however, the source medium flow can also comprise a liquid fluid, in particular water or an oil or a mixture of water or an oil with another fluid. Alternatively or additionally, the cooling medium flow that flows 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.In principle, 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 heating circuit. The useful heating 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.According to a further embodiment, the device can include a recuperator through which working fluid vapor from the expansion machine flows on a primary recuperator side and liquid working fluid flows on a secondary recuperator side before the liquid working fluid is fed to the working fluid evaporator. 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 varied by the control unit to adjust the saturation level to the predetermined saturation level, which is between 95% and 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. 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.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 from a source medium stream in a working fluid evaporator, absorbing heat, and is fed 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 onto a cooling medium from a cooling medium stream in a condenser, dissipating heat. The degree of saturation of the working fluid vapor can be detected at a position in the working fluid circuit downstream of the working fluid evaporator and upstream of the expansion machine by means of a vapor saturation sensor.Furthermore, a control variable for the degree of saturation can be varied depending on the saturation level measurements provided by the steam saturation sensor in order to adjust the saturation level to the predetermined level. 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 measurements 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 measurements are equal to 100%, the working fluid volume flow rate through the working fluid evaporator can be increased. In 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. 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 degree of saturation 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, while damage to the expansion machine caused by excessive liquid content in the working fluid vapor is effectively prevented. 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. Advantageous embodiments of the invention are illustrated in the drawings and described below. Figure 1 shows 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; Figure 2 shows...Figure 2 shows 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; Figure 3 shows 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 Figure 4 shows 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. The diagram in Figure 3 shows the system diagrams of the ORC system and the ORC system.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 vapor, into liquid working fluid. The working fluid can in particular be a so-called dry medium, which means that the Ts diagram of the working fluid has a positive slope of the saturated vapor curve. The working fluid can in particular be 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 working fluid circuit. To generate electrical energy, the expansion machine 19 is coupled to an electric generator G. 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. 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 primary side of the working fluid evaporator 111 has a source medium inlet 111' and a source medium outlet 111''.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 evaporate 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'. Working fluid evaporated in the working fluid evaporator 11 is conveyed through the working fluid outlet 112'' of the secondary side 112 of the working fluid evaporator to the expansion machine 19. The source medium stream can be supplied at the source medium inlet 111' of the primary side 111 of the working fluid evaporator, for example, at a temperature T. Q_V_ein enters the working fluid evaporator 11 at 500 °C and has an initial temperature T Q_V_ausThe working fluid vapor 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 stream from an industrial process and / or an internal combustion engine. A vapor saturation sensor 13 is arranged in the working fluid circuit 10 between the working fluid outlet 112'' of the secondary side 112 of the working fluid evaporator 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, with indirect detection meaning that a measured quantity detected by the vapor saturation sensor can be converted into a degree of saturation.Saturation values ​​recorded by the steam 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 supply the working fluid steam to the expansion machine 19 essentially without superheating, while still ensuring a sufficiently high degree of saturation, for example 95% to 100%, and especially exactly 100%. As it passes through the expansion machine 19, the working fluid steam is expanded and then directed into the condenser 12. Here, heat is extracted from the working fluid steam 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 condenser secondary side 121 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 condenser secondary side 121. This corresponds to the inlet temperature T. KM_K_ein of 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 outlet temperature T. KM_K_ausfrom, for example, 80 °C. 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. 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. 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 material leaves the recuperator 16 at a working material outlet 162'' of the recuperator secondary side 162.As the working fluid vapor passes through the expansion machine 19, it expands and enters the recuperator 16 via a working fluid inlet 161'. In the recuperator 16, heat is transferred from the working fluid vapor on the recuperator primary side 161 to the liquid working fluid on the recuperator secondary side 162. This preheats the liquid working fluid before it flows into the working fluid evaporator 11, increasing the mechanical and / or electrical efficiency of the device 100. After the recuperator 16, the working fluid, which is still at least partially in the form of working fluid vapor, flows from a working fluid outlet 161'' of the recuperator primary side 161 into the condenser 12.The working fluid condensed on the primary side 122 of the capacitor is subsequently fed in liquid form to a working fluid reservoir 14, which may be arranged below the capacitor 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 a sense, as an intermediate storage tank for liquid working fluid before it is fed back 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. 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. 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, a manipulated variable for regulating the degree of saturation can be varied by the control unit 17 in order to adjust the saturation degree to the predetermined saturation level. The manipulated variable is output via a signal output 171, which is operationally connected to the feed pump 15. The control variable can in particular include a working fluid volume flow through the working fluid evaporator 11, especially a time-related delivery rate of the feed pump 15.Preferably, the manipulated variable comprises the rotational speed of the feed pump 15. The control device 17 can, for example, comprise a programmable logic controller (PLC) in which a program for controlling the degree of saturation can be executed. In particular, the control device 17 can include at least one microprocessor. In embodiments, the predetermined degree of saturation, to which the control device adjusts the actual degree of saturation, can be between 95% and 100%. Preferably, the predetermined degree of saturation is exactly 100%, since this achieves the optimal efficiency. 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 fully depicted here, but only the isobaric heat input (in the evaporator) and the expansion in the turbine. Entropy (unit kJ / kg∙K) is plotted on the x-axis and temperature (unit °C) on the y-axis. The state-of-the-art process comprises the following steps: abfgh: 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: superheating in the working fluid evaporator 11; gh: expansion in the expansion engine 19. The working fluid is fed into the working fluid evaporator 11 at a pressure of approximately 16 bar, which is generated by the feed pump 15. The compression step is not shown in the diagram.The process carried out in the working fluid circuit 10 of the ORC system of the device 100 according to the invention comprises the steps acd-e: ac: temperature increase of sensible heat in the working fluid evaporator 11; cd: heat input of latent heat (enthalpy of vaporization) in the working fluid evaporator 11; de: expansion in the expansion machine 19. The working fluid is supplied to the working fluid evaporator 11 at a pressure of approximately 17 bar, the pressure being generated by the feed pump 15. The compression step is not shown in the diagram. 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. In the state-of-the-art process, however, 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 fluid circuit of the device according to the invention) and h (process according to the prior art), which describe the state of the working fluid after expansion in the expansion machine, it is evident that the process carried out in the working fluid circuit 10 of the ORC system of the device 100 according to the invention generates a higher output than the process according to the prior art.

[0002] Reference numeral list 100 Device for generating electrical and / or mechanical energy 10 Working fluid circuit 11 Working fluid evaporator 111 Working fluid evaporator primary side 111' Source medium inlet 111'' Source medium outlet 112 Working fluid evaporator secondary side 112' Working fluid inlet 112'' Working fluid outlet 12 Condenser 121 Condenser secondary side 121' Cooling medium inlet 121'' Cooling medium outlet 122 Condenser primary side 13 Vapor saturation sensor 14 Working fluid reservoir 141 Working fluid inlet 142 Working fluid outlet 15 Feed pump 151 Suction side 152 Pressure side 16 Recuperator 161 Recuperator primary side 161' Working fluid inlet 161'' Working fluid outlet 162 Recuperator secondary side 162' Working medium inlet 162'' Working medium 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_ausOutput temperature of source medium flow from working fluid evaporator T KM_K_ein Inlet temperature of cooling medium in condenser T KM_K_aus Output temperature of cooling medium from condenser

Claims

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), 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 is supplied to the expansion machine (19) 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 the 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 configured 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 any 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, an optical measuring principle, an acoustic measuring principle, in particular ultrasound, and / or a fluid dynamic measuring principle, in particular based on a pressure drop.

6. Device (100) according to any one of the preceding claims, comprising a working fluid collection container (14) which is arranged downstream of the condenser (12) and is configured to collect working fluid condensed in the condenser (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 tank (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 tank (14).

8. Device (100) according to one of claims 2 to 7, comprising a control device (17) configured for controlling the degree of saturation and further configured to receive saturation degree measurements from the vapor saturation sensor (13), wherein, depending on the saturation degree measurements, a manipulated variable for controlling the degree of saturation by the control device (17) can be varied in order to adjust the degree of saturation to the desired level.

9. Device (100) according to claim 8, wherein the manipulated variable comprises a working fluid volume flow rate through the working fluid evaporator (11), in particular wherein the manipulated variable comprises a time-related delivery rate of the feed pump (15).

10. Device (100) according to any one of the preceding claims, wherein the predetermined saturation level 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 configured 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 manipulated 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 from a source medium stream in a working fluid evaporator (11) by absorbing heat 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 onto a cooling medium of a cooling medium stream in a condenser (12) by removing heat. 13.The method of claim 12, wherein the saturation level of the working fluid vapor is detected by a vapor saturation sensor (13) at a position in the working fluid circuit (10) downstream of the working fluid evaporator (11) and upstream of the expansion machine (19), and wherein a control variable for regulating the saturation level is varied depending on the saturation level measurements provided by the vapor saturation sensor (13) in order to adjust the saturation level to the predetermined saturation level. 14.Method according to claim 13, - wherein the control variable for regulating the degree of saturation comprises a working fluid volume flow rate 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 wherein, when saturation degree measured values ​​are less than 100%, in particular less than 95%, the working fluid volume flow rate through the working fluid evaporator (11) is reduced and / or when saturation degree measured values ​​are equal to 100%, the working fluid volume flow rate through the working fluid evaporator (11) is increased.

15. A method according to claim 13 or 14, wherein the vapor saturation sensor (13) directly detects the degree of saturation.

16. A 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 method, in particular wherein the predetermined calculation method comprises an at least sectionally linear relationship between the volumetric void fraction and the degree of saturation.

17. A 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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