EP2865854A1 - Device and method for reliable starting of ORC systems - Google Patents

Abstract

A thermodynamic cycle apparatus comprising: a working medium; an evaporator (2) for evaporating the working medium; an expansion machine (3) for generating mechanical energy while relaxing the vaporized working medium; a condenser (4) for condensing the working fluid, and a pump (1) for pumping the condensed working fluid to the evaporator, wherein the geometric arrangement of the evaporator is selected such that prior to starting the pump the condensed working fluid flows from the condenser to the evaporator by gravity and the working medium can circulate in a closed circuit over the evaporator and the condenser, whereby in particular a predetermined flow height of the liquid working medium can be provided to the pump. Furthermore, a method for starting the thermodynamic cycle apparatus according to the invention, comprising the following steps: applying heat to the evaporator and evaporating the working medium in the evaporator whereby working medium flows to the condenser; Condensing the working medium in the condenser; Starting the pump when reaching or exceeding a predetermined flow height of the working fluid to the pump.

Description

Field of the invention

The invention relates to a thermodynamic cycle device, in particular an organic Rankine cycle device, comprising: a working medium; an evaporator for evaporating the working medium; an expansion machine for generating mechanical energy while relaxing the vaporized working medium; a condenser for condensing and possibly subcooling the working medium, in particular the working medium expanded in the expansion machine; and a pump for pumping the condensed working fluid to the evaporator during operation of the thermodynamic cycle device. The invention further relates to a method for starting such a thermodynamic cycle device.

State of the art

An ORC system consists of the following main components: A feed pump, which delivers the liquid working fluid to the evaporator under high pressure increase, an evaporator in which the working fluid is evaporated, an expansion machine in which the high pressure steam is expanded, thereby generating mechanical energy which can be converted to electrical energy via a generator and a condenser in which the low-pressure steam from the expansion machine is liquefied. From the condenser, the liquid working medium reaches the feed pump of the system via a possible storage container (feed container) and a suction line.

When starting the working medium should be present in sufficient quantity in the suction line of the pump, or the food container as possible, so that during the entire start the pump has sufficient medium available.

A second condition for the trouble-free pumping of working fluid through the pump is a sufficient flow height of the applied to the pump fluid (working fluid). The flow height (NPSH) is a parameter that is influenced not only by the geodetic flow height but also by the thermodynamic state of the working fluid, which can be explained as follows. If the subcooling (the distance to the boiling point) of the fluid at the inlet of the pump is not sufficiently high, it can lead to a brief evaporation of the fluid at the pump inlet. This phenomenon can cause damage to the pump and partial or complete cessation of the flow. One speaks of cavitation. The distance to the boiling pressure of the fluid at the inlet of the pump is referred to as the flow height. One parameter for quantifying this is the Net Positive Suction Head (NPSH) value. Here, a distinction is made between required, pump-specific (NPSH _r ) and adjacent (NPSH _a ) flow height, wherein the applied NPSH _a value of several system and operation-specific parameters (temperature, pressure due to geodetic flow height, saturation pressure, Inertgaspartialdruck, the inert gas partial pressure additional partial pressure of a non-condensing gas, which may additionally be present in the circulation) is dependent. For safe operation of the pump, the applied NPSH _a value must always be above the required NPSH _r value.

Especially for circulatory systems like an ORC, cavitation is a challenge. Here, liquid condensate must be pumped with little or no distance to the boiling point and consequently a low applied NPSH _a value. Since the required NPSH _r value is determined by the pump design, this can only be influenced to a limited extent and it must be ensured at each operating time, in terms of process technology, that the applied NPSH _a value does not fall below the required value.

Shutting down an ORC system, for example, by eliminating / shutting off the heat source or by emergency shutdown of the system may result in uncontrolled distribution of working fluid in the system (eg in expansion machine, horizontal pipes or liquid bags), with the working fluid not flowing to the food container. This can lead to insufficient working fluid for the feed pump for the entire starting process Available. The start-up process includes filling the evaporator, evaporation of working medium and thereby build up of pressure, starting the expansion machine and the beginning of condensation and thus return flow of working fluid to the feed pump.

The unfavorable distribution of working medium and the associated difficult or even impossible start-up is a known problem, for which there are various solutions according to the prior art. In EP 2 613 025 A1 An ordered distribution of the working medium by a sudden opening of a valve and a "flushing" of system parts with accumulations of liquid working medium is proposed (System and methods for cold startup of rankine cycle devices). However, this requires one or more valves as additional components. In EP 2 345 797 A2 (Fluid feedback pump to improve cold start performance of organic rankine cycle plants) the working fluid is pumped by means of additional pumps to the correct points of the system. Again, additional components in the form of pumps are necessary to guarantee a reliable start of the system.

The prior art further teaches that steam lines are always to be laid falling to the condenser / food tank. This means that the evaporator must be placed at the highest point and at standstill condensate flows through the condenser towards the feed tank. But this is difficult or impossible to realize in the compact design of ORC systems, especially when a maximum height is to be maintained. Even if the evaporator is placed at the highest point, which would result in the automatic collection of the working medium in the condenser / feed tank, the problem of system conditions with insufficient adjacent leading height NPSH _a as described above would not be resolved.

However, a further problem can not be solved by the two listed disclosures from the prior art: When starting up the ORC system, a situation may arise in which the feed pump and possibly also its supply line have a higher temperature than the aspirated working medium from the condenser or as the just in the condenser condensing working medium. The condenser, which serves as a heat sink in the circuit, can be the coldest at standstill In the system, for example when the external condenser is installed outdoors in air at cold outside temperatures and a pump located in a machine housing / building, which is at a temperature that is higher than the outside temperature. Due to the large existing in the condenser heat exchanger surfaces or due to the residence time of the medium in the condenser, the pump can be tempered even temporarily at the same ambient temperatures of the pump and condenser higher than the condenser. Thus, there is an increase in temperature from the condenser to the feed pump and this reduces the applied flow height at the pump inlet (NPSH _a ). As a result, the pump cavitates and no working fluid is delivered. This prevents the system from starting and can cause damage to the pump. Even after a temperature equalization of feed pump, supply line and condenser, especially in compact systems without large height differences and thus geodetic lead height, the then applied flow height NPSH _{a be} lower than the necessary flow height NPSH _r , which in turn has cavitation.

The problem of cavitation in ORC systems is well known and can be found in the disclosure in DE 10 2009 053 390 B3 be dissolved for example by adding inert gas in a food container / condenser.

In summary, the following may be stated as motivation for the present invention. To safely start up an ORC system, there must be sufficient working fluid with a sufficient supply head at the system's feed pump. In an ORC cycle, a maldistribution of liquid working fluid may occur at standstill or in poorly controlled shutdown of the system, preventing startup due to lack of fluid in front of the feed pump. In addition, a detrimental temperature distribution in the working fluid circuit can be adjusted, for example, the working fluid could be warmer in the original area of the feed pump than at the coldest point in the system. By in this state low applied to the pump flow height can lead to cavitation of the pump. This prevents a reliable start of the system. In colder weather, a cold system condition can prevent the system from starting up. For example, it may lead to an increase in the viscosity of the working medium or another medium present in the circuit, such as a lubricant, come, which may affect a delivery of the medium by the feed pump.

Description of the invention

The object of the invention is at least partially overcome the disadvantages described above.

This object is achieved by a device according to claim 1.

The thermodynamic cycle device according to the invention, in particular ORC device, comprises a working medium; an evaporator for evaporation and optionally additional overheating of the working medium; an expansion machine for generating mechanical energy while relaxing the vaporized working medium; a condenser for condensing and optionally additional subcooling of the working medium, in particular of the working medium expanded in the expansion machine; and a pump for pumping the condensed working fluid to the evaporator in operation of the thermodynamic cycle apparatus, wherein the geometric arrangement of the evaporator is selected so that before starting the pump, the condensed working fluid from the condenser to flow by gravity to the evaporator and the working fluid in a closed circuit over the evaporator and the condenser can circulate, whereby in particular at least a predetermined minimum flow height of the liquid working medium can be provided to the pump.

It is advantageous that a sufficient for trouble-free starting of the pump flow height when starting the thermodynamic cycle device is provided. The closed circuit (which at standstill shut-off devices, which could prevent the circulation are not closed) is constructed in such a way that the circulating fluid flows by gravitational forces without additional drive to the evaporator. When starting the system from standstill, the evaporator is charged with heat, making it the warmest component in the system. The working medium contained therein is vaporized and possibly also overheated and the resulting vapor heats all system components lying above the evaporator. If liquid medium has accumulated in other parts of the system (eg expansion machine, horizontal pipes or liquid sacks), it will be vaporized by heating and then condensed at the coldest point of the system. The coldest point in the system is normally the capacitor. If this is not the case at standstill, the condenser can be set as the coldest point by controlling the heat sink (eg starting the cooling on the condenser). From the condenser, the working fluid flows as a template to the feed pump. The geometric arrangement is chosen (height difference) so that the condensate can flow by gravity to the evaporator (density difference between vapor and liquid). It creates a natural circulation, which sets an independent order of the liquid working medium. This means that liquid working fluid is collected in the low-lying part of the system (eg in front of the pump), and that before starting the pump there is sufficient working fluid with sufficient flow height in front of the pump.

According to a development of the device according to the invention, the evaporator can be located in the geometric arrangement in a lower height than the capacitor. A relative to the condenser deep-lying evaporator and possibly also lower-lying pipes represent a possibility that the fluid in the circulation flows by gravitational forces without additional drive to the evaporator.

Another development is that the closed circuit between the condenser and evaporator also includes the non-started pump and / or wherein the closed circuit between evaporator and condenser also includes the expansion machine. In this way, when working fluid-permeable designs of the pump, the working fluid in the circuit can also flow through the pump without it being started.

According to another development, the pump may be located at a lower level than the evaporator. Thus, the lead height can be further increased.

Another development is that the thermodynamic cycle apparatus may further include a bypass valve for bypassing the expander in the circuit.

According to another development, the thermodynamic cycle apparatus may further comprise a food container for collecting the condensed working medium, wherein the food container in a closed circuit between the condenser and evaporator, in particular between the condenser and the pump is arranged.

Another development consists in that at least one sensor for measuring the flow height of the working medium upstream of the pump, in particular a sensor for measuring the pressure of the working medium and / or a sensor for measuring the temperature of the working medium can be provided.

According to another development, the thermodynamic cycle apparatus may further comprise a bypass valve for bypassing the pump in the circuit.

According to another development, the thermodynamic cycle apparatus may further comprise a recuperator for transferring heat energy from the expanded working medium to the working medium pumped between the pump and the evaporator during operation of the thermodynamic cycle apparatus, the recuperator being disposed between the expander and the condenser; and a bypass valve for bypassing the recuperator in the circuit, wherein the bypass valve for bypassing the recuperator in particular also the bypass valve for bypassing the pump can be.

When a recuperator is used and, for example, the piping between pump and evaporator passes over the recuperator to preheat the working medium pumped during operation (normal operation) of the thermodynamic cycle apparatus with heat from the expanded, vaporized working medium after the expander and before the condenser to the According to the invention starting the cycle device, a bypass valve for bridging the recuperator be provided because otherwise can be done by the recuperator, which is higher than the evaporator, no natural circulation.

The above object is further achieved by a method according to claim 10.

The method according to the invention for starting a thermodynamic cycle apparatus according to the invention or one of its developments comprises the following steps: applying heat to the evaporator and evaporating the working medium in the evaporator, optionally additionally also overheating the working medium in the evaporator, whereby working medium flows to the condenser; Condensing the working medium in the condenser; Starting the pump when reaching or exceeding a predetermined flow height of the working fluid to the pump.

The inventive method has the advantages that have already been described in connection with the device according to the invention.

The method according to the invention can be further developed in that the pump is started after reaching or exceeding a measured flow height or after a predetermined time after the start of the pressurization of the evaporator with heat.

According to another development, the method may comprise the following further steps: setting the condensation temperature to a first temperature value; and adjusting the condensation temperature to a second temperature value after the condensed working fluid having the first temperature value reaches the pump; wherein the second temperature value is greater than the first temperature value. The coldest point in the system is normally the capacitor. If this is not the case at standstill, the capacitor can in this way, for example via a Control of the heat sink to be set as the coldest point (eg start of the cooling on the condenser).

According to another embodiment, the setting of the condensation temperature to a second temperature value by reducing the speed of a condenser fan and / or by lowering a cooling water mass flow or the air mass flow and / or by increasing the temperature of the cooling water mass flow or the air mass flow through the capacitor. Alternatively or additionally, further measures, such as e.g. Closing blinds or flaps of the condenser will increase the condensation temperature.

Another development is that the further steps of opening the expansion machine bypass valve prior to or simultaneously with applying heat to the evaporator or opening the expander bypass valve a predetermined first period of time after applying the evaporator with heat or after reaching a predetermined first pressure the expansion machine; and closing the expansion machine bypass valve after or coincidentally with the start of the pump or closing of the expansion machine bypass valve may be provided a predetermined second time period prior to starting the pump or upon reaching a predetermined second pressure at the expansion machine.

According to another embodiment, the following further steps may be provided: opening the pump bypass valve and / or recuperator bypass valve before, during or a predetermined third period of time after applying heat to the evaporator; and closing the pump bypass valve and / or recuperator bypass valve after, or during, a predetermined fourth period of time prior to starting the pump.

The said developments can be used individually or combined with each other.

Further features and exemplary embodiments and advantages of the present invention will be explained in more detail with reference to the drawings. It is understood that the embodiments do not exhaust the scope of the present invention. It is further understood that some or all of the features described below may be combined with each other in other ways.

drawings

FIG. 1

shows the height arrangement in a thermodynamic cycle device, in particular in an ORC system, according to the present invention.

FIG. 2

shows an embodiment with combinable advantageous developments of the thermodynamic cycle device according to FIG. 1 ,

FIG. 3

shows another embodiment of the thermodynamic cycle device according to the invention.

embodiments

FIG. 1 shows a thermodynamic cycle device, in particular an ORC system and the height-ordered arrangement of the main components. The system comprises a feed pump 1, which conveys the liquid working medium under high pressure increase to an evaporator 2, in which the working medium is evaporated, an expansion machine 3, in which the high-pressure steam is expanded while mechanical energy is generated. This can be converted, for example via a generator G into electrical energy. From the condenser 4, in which the low-pressure steam from the expansion machine 3 is liquefied, the liquid working medium passes through a possible (optional) Reservoir (food container) and a suction line back to the feed pump 1 of the system.

In the following, a description of the startup process is given and the problem solution is explained by the arrangement described.

Automatic order of the liquid working medium: The system should start from standstill. Heat is first applied to the evaporator (if the heat is not applied to the evaporator uncontrolled, for example by continuous flow with a heat transfer medium, this must be switched on). Steam forms in the evaporator, which heats the system components, vaporizes liquid working medium in other parts of the system (for example in an expansion machine, horizontal pipes or liquid bags) and flows together with them to the condenser where it liquefies after some time. It thus happens a fluid displacement from the evaporator to the condenser. This leads to an increase in the fluid level on the condenser side, which in turn leads to a pressure gradient from the cold condenser side to the hot evaporator side. The described connection (without closed shut-off devices) generates a flow which causes medium from the condenser to flow to the evaporator via the pump. The track must be designed so that the flow is adjusted solely by gravity. For this, the pressure losses of the installed components or opening pressures of installed valves must be taken into account.

Creation of flow height and system start: The orderly distribution of liquid medium (as described above) and collecting a sufficient amount of working fluid in front of the pump does not guarantee that the medium with sufficient flow height (NPSH _a ) is applied to the pump to start the Allow pump. In order to produce a sufficient lead height, the following procedure can be followed. By cooling the capacitor (by a heat sink such as ambient air or cooling water), the condensation temperature and consequently the pressure in the condenser is first reduced. Low temperature condensate flows out of the condenser into the feed box (if present) and into the supply line to the pump. After some time, the fluid reaches the pump with the resulting low condensation temperature due to natural circulation. Now, for example by controlling the heat sink, the temperature in the condenser increases, which also increases the pressure in the condenser. This can be done for example by lowering the speed of a condenser fan and / or by lowering a cooling water mass flow or the air mass flow and / or by increasing the temperature of the cooling water mass flow or the air mass flow through the condenser. Due to the colder, applied to the pump fluid, and the increased pressure in the condenser, the applied flow height increases at the pump. After exceeding a limit value of the flow height (NPSH _a > NPSH _r ) or after a certain, experience-based time, the pump can be started to start the regular start-up process of the ORC system.

The prior art, by contrast, teaches (as stated above) that steam lines should always be laid down to the condenser / food tank.

The device after FIG. 2 includes to improve in FIG. 1 arrangement shown additional components. These and their function will be described below.

Component 5 denotes a bypass valve on the expansion machine 3. This bypass valve 5 via the expansion machine allows e.g. in volumetric expansion engines, a sufficient amount of vapor generated in the evaporator can flow to the condenser 4. The bypass valve can also serve as an emergency shut-off valve, which allows rapid release of the high-pressure steam in front of the expansion machine in case of danger. The bypass valve may e.g. be executed as a normally open solenoid valve. In the case of starting with the described arrangement of the components, the valve remains open and thus allows the natural circulation of the working medium. The valve is required for the described function if the amount of working fluid via a stationary (or rotating) expansion machine is not sufficient for the intended natural circulation of the fluid.

The component 6 denotes a food container. The food container may be required to provide sufficient working fluid to the feed pump in each operating condition. It buffers the total working medium and thus prevents the standstill of the plant in case of loss of working fluid, unequal distribution of working fluid, different vapor densities and thus steam masses during operation and standstill or inaccurate filling of the system. In conjunction with the use of inert gas to the container to another function. It increases the gas volume in the system. This means that the flow height can be kept relatively constant over all operating states (see also the disclosure in DE 10 2009 053 390 B3 ). When using inert gas to prevent cavitation, another advantage results from the described arrangement in natural circulation. A constant circulation of working medium, which is caused solely by the temperature difference and the resulting pressure difference between evaporator and condenser and is independent of the operation of the feed pump, ensures that the circulating inert gas automatically accumulates in the condenser and food tank. As in DE 10 2009 053 390 B3 described, increases the inert gas, which is present in the food container, due to its concentration-dependent partial pressure, the flow height to the pump. Since the inert gas is distributed by diffusion in the entire system during standstill and thus the partial pressure in the food container decreases, without a concentration of the inert gas in the food container by, for example, the described natural circulation a cavitation-free start of the pump from standstill can not always be guaranteed. This must be compensated by a larger inert gas and / or a larger food container with a larger volume of steam, so that the system can be safely approached from standstill. The necessary amount of inert gas can be reduced by the described method, resulting in an increasing pressure difference at the expansion machine and a higher generated power (increase in system efficiency).

The component 7 denotes sensors for measuring the applied flow height (NPSH _a ). By a possible attachment of sensors (here eg pressure P and temperature T), the flow height (NPSH _a ) can be determined. This can serve as a start criterion for the start of the pump in the described start-up of the system.

The component 8 designates a bypass valve around the feed pump. This valve 8 for bypassing the feed pump can be used in the described case to to ensure a sufficient flow of liquid working fluid from the condenser to the evaporator. This is necessary, for example, if the feed pump, due to its construction / design (eg positive displacement pump) at standstill, is impermeable to the medium. Another reason could be the large height difference to be overcome in the pump (eg in vertical multistage centrifugal pumps), which prevents natural flow. The bypass valve can be made switchable or adjustable. In addition, it can be designed as a spring-loaded valve with adjustable or fixed opening and closing pressures. The valve thus opens only at a certain applied pressure difference between the suction and pressure side of the pump and remains closed during operation of the system or the valve is open to a certain pressure difference between the pressure and suction side and automatically closes when operating from this certain pressure difference between pressure and suction side. The pressure difference to open the valve must be so small that a natural circulation is possible. In addition, the valve can serve as a safety valve in case of danger. Due to the rapid opening of the valve in case of danger, medium can flow from the evaporator in the direction of the condenser. This prevents excessive pressure increase in the evaporator by further evaporation of working fluid. In order to prevent backflow of working fluid from the evaporator to the pump at certain operating points, for example, to protect the pump from hot working fluid, also a check valve (not shown in the drawing) can be used downstream of the pump.

In FIG. 3 an embodiment of the thermodynamic cycle device is shown with a recuperator 9. The recuperator 9 serves to transfer heat energy from the expanded working medium to the working medium pumped between the pump 1 and the evaporator 2 during operation of the thermodynamic cycle apparatus, the recuperator 9 being arranged between the expansion machine 3 and the condenser 4. Furthermore, a bypass valve 8 is provided for bridging the recuperator 9 in the circuit, wherein the bypass valve 8 for bypassing the recuperator 9 here also the bypass valve 8 to bypass the pump 1 is simultaneously. When the pipeline between pump 1 and evaporator 2 runs over the recuperator 9 to the working medium pumped therein in the normal operation of the thermodynamic cycle apparatus with heat from the expanded vaporized working medium between the expansion machine 3 and To preheat the condenser 4, the bypass valve 8 must be open for bridging the recuperator 9 for starting the cycle device according to the invention, because otherwise no natural circulation of the working medium can take place through the recuperator 9, which is arranged higher than the evaporator 2.

In summary, the method according to the invention and the device according to the invention (height arrangement) ensure that the ORC can be started reliably and quickly. The method requires in the simple arrangement no sensors or actuators (eg valves) for safe start. Due to the automatic distribution of the working medium in the system, the total amount of working medium in the system can be reduced in comparison to systems arranged differently (eg with an elevated evaporator and low-lying condenser or expansion machine), as due to the drive-free arrangement of liquid working medium always sufficient fluid in the suction line the pump is present. The automatic heating of the system by the natural circulation with heat supply ensures a preheating of the components. In cold weather, this can speed up system start-up and extend the life of the components. The safe, cavitation-free start-up of the system prevents possible damage to the pump, which can occur due to (partial) cavitation on the pump. By the method, a sufficient flow height for the feed pump can be ensured during the starting process. Thus, other methods, which would otherwise be necessary for generating a lead-in height, can be omitted, or their effect on the efficiency of the system can be reduced. Since other methods (eg condensate supercooling or inert gas addition) have a performance-reducing effect, the method described leads to an increase in the overall efficiency of the ORC system. By the method described, the amount of working fluid can be saved. Experience shows that the startability of ORC systems can otherwise only be guaranteed by using large quantities of working medium. The working medium with prices of 20-80 € / kg has a significant impact on the profitability of ORC systems. Lower levels of content can also extend mandatory maintenance intervals and reduce maintenance (F-Gas Regulation), which can lead to significant cost reductions during operation. To be considered is, however, that the heat input into the system not self-locking - can be stopped - such as by an overhead evaporator. Although this may be a disadvantage eg for maintenance activities, it may be necessary to prevent the heat input via other, additional measures.

The illustrated embodiments are merely exemplary and the full scope of the present invention is defined by the claims.

Claims (15)

Thermodynamic cycle device, in particular an organic Rankine cycle device, comprising: a working medium; an evaporator for evaporation and optionally additional overheating of the working medium; an expansion machine for generating mechanical energy while relaxing the vaporized working medium; a condenser for condensing and optionally additional subcooling of the working medium, in particular of the working medium expanded in the expansion machine; and a pump for pumping the condensed working fluid to the evaporator during operation of the thermodynamic cycle apparatus; wherein the geometric arrangement of the evaporator is selected so that before starting the pump, the condensed working fluid from the condenser flow by gravity to the evaporator and the working fluid can circulate in a closed circuit through the evaporator and the condenser, whereby in particular at least a predetermined minimum flow height the liquid working medium can be provided to the pump. Thermodynamic cycle apparatus according to claim 1, wherein the evaporator is located in the geometric arrangement at a lower level than the condenser. Thermodynamic cycle device according to claim 1 or 2, wherein the closed circuit between the condenser and the evaporator also comprises the non-started pump and / or wherein the closed circuit between evaporator and condenser also comprises the expansion machine. A thermodynamic cycle apparatus according to any one of claims 1 to 3, wherein the pump is at a lower elevation than the evaporator. Thermodynamic cycle apparatus according to one of claims 1 to 4, further comprising a bypass valve for bypassing the expansion machine in the circuit. Thermodynamic cycle device according to one of claims 1 to 5, further comprising a food container for collecting the condensed working medium, wherein the food container in a closed circuit between the condenser and evaporator, in particular between the condenser and the pump is arranged. Thermodynamic cycle device according to one of claims 1 to 6, further comprising: at least one sensor for measuring the flow height of the working medium in front of the pump, in particular a sensor for measuring the pressure of the working medium and / or a sensor for measuring the temperature of the working medium. Thermodynamic cycle device according to one of claims 1 to 7, further comprising a bypass valve for bypassing the pump in the circuit. Thermodynamic cycle device according to one of claims 1 to 8, further comprising: a recuperator for transferring heat energy from the expanded working fluid to the working fluid pumped between the pump and the evaporator during operation of the thermodynamic cycle apparatus, the recuperator disposed between the expander and the condenser; and a bypass valve for bypassing the recuperator in the circuit, wherein in combination with claim 8, the bypass valve is provided for bridging the recuperator in particular as a bypass valve for bypassing the pump. Method for starting a thermodynamic cycle device according to one of claims 1 to 9, the method comprising the following steps: Applying heat to the evaporator and evaporating the working medium in the evaporator, optionally additionally also overheating the working medium in the evaporator, whereby working medium flows to the condenser; Condensing the working medium in the condenser; Starting the pump when reaching or exceeding a predetermined flow height of the working fluid to the pump. The method of claim 10, wherein the starting of the pump after reaching or exceeding a measured flow height takes place or takes place after a predetermined time after the start of the charging of the evaporator with heat. Method according to claim 10 or 11, with the further steps: Setting the condensation temperature to a first temperature value; and Setting the condensation temperature to a second temperature value after the condensed working fluid having the first temperature value reaches the pump; wherein the second temperature value is greater than the first temperature value. The method of claim 12, wherein adjusting the condensation temperature to a second temperature value by lowering the speed of a condenser fan and / or by lowering a cooling water mass flow or the air mass flow and / or by an increase in temperature of the cooling water mass flow or the air mass flow through the capacitor. Method according to one of claims 10 to 13, with the further steps: Opening the expansion machine bypass valve prior to, or concurrent with, charging the evaporator with heat or opening the expander bypass valve a predetermined first time period after applying heat to the evaporator or after reaching a predetermined first pressure on the expander; and Closing the expander bypass valve after or coincidentally with the start of the pump or closing the expander bypass valve a predetermined second time period before starting the pump or after reaching a predetermined second pressure on the expander machine. Method according to one of claims 10 to 14, with the further steps: Opening the pump bypass valve and / or recuperator bypass valve before, during or a predetermined third period of time after applying heat to the evaporator; and Closing the pump bypass valve and / or recuperator bypass valve after, during or a predetermined fourth time period prior to starting the pump.

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