EP3006682A1 - Device and method for operating a heating distribution station - Google Patents

Abstract

The invention relates to a heat transfer station for transferring heat from a supplier heat network with a first heat-conducting fluid to a customer heat network with a second heat-conducting fluid, wherein the heat transfer station comprises a thermodynamic cycle device with a working medium, in particular an ORC device with an organic working medium, and wherein the Thermodynamic cycle apparatus comprises: a first heat exchanger configured as an evaporator for vaporizing and optionally additional overheating of the working medium while supplying heat from the first fluid, an expansion machine for generating mechanical energy by relaxing the vaporized working medium, a generator coupled to the expansion machine for at least partial conversion the mechanical energy into electrical energy, designed as a capacitor second heat exchanger for condensing the relaxed Arbeitsmedi ums and transferring heat energy from the expanded working fluid to the second fluid, and a feed pump for conveying the condensed working fluid under pressure increase to the evaporator. Furthermore, the invention relates to a corresponding method for transferring heat.

Description

Field of the invention

The invention relates to a heat transfer station for transferring heat from a supplier heat network with a first heat-conducting fluid to a customer heat network with a second heat-conducting fluid. Furthermore, the invention relates to a method for transferring heat from a supplier heat network with a first heat-conducting fluid to a customer heat network with a second heat-conducting fluid.

State of the art

District heating refers to the supply of buildings with heating and hot water. For example, water is well suited as a medium for heat transport, where it is used liquid or in vapor form. The medium is conveyed in heat-insulated pipelines in a continuous circulation. Local heat is a corresponding heat transfer for heating purposes over relatively short distances, but the transition to district heating is fluid.

Heat transfer stations connect such local and district heating networks with heat consumers. The operating temperatures of the district heating networks are based on the consumers with the highest required temperature level. In the city center of Munich, for example, the temperature of the district heating supply is 130 ° C in winter and 80 ° C in summer. The temperature of the return must not exceed 45 ° C. These temperatures are among the parameters that are usually specified in the technical connection conditions of the respective utility company and must be maintained by the operating mode and design of the system. However, the vast majority of consumers require lower flow temperatures for their heating systems. In the case of residential buildings, the required flow temperature of the hot water supply is Usually at about 60-65 ° C, and therefore must be lowered in the prior art, first by mixing colder water, the temperature. In this way, however, a large part of the theoretically usable potential (exergy) of the hot water is wasted, which is disadvantageous. It is therefore transported according to the prior art heat at high temperature levels over long distances and then lowered under Exergievernichtung to a low temperature level.

Description of the invention

The object of the invention is to overcome this disadvantage and to better exploit the potential of district heating.

This object is achieved by a heat transfer station according to claim 1.

The heat transfer station according to the invention for transferring heat from a supplier heat network with a first heat-conducting fluid to a customer heat network with a second heat-conducting fluid comprises a thermodynamic cycle device with a working medium, in particular an ORC device with an organic working medium, the thermodynamic cycle device comprising: an evaporator formed first heat exchanger for preheating, evaporation and optionally additional overheating of the working fluid under heat from the first fluid, an expansion machine for generating mechanical energy by relaxing the vaporized working medium, coupled to the expansion machine generator for at least partially converting the mechanical energy into electrical Energy, designed as a capacitor second heat exchanger for condensing the relaxed working fluid and transfer of heat nergie from the relaxed working fluid to the second fluid, and a feed pump for conveying the condensed working fluid under pressure increase to the evaporator. Optionally, in the condenser prior to condensation, a desuperheating of the working medium take place. Furthermore, optionally in the condenser after condensing, an undercooling of the working medium under the condensation temperature. The first heat-conducting fluid and the second heat-carrying fluid may be the same fluid. Heat is transferred from a network at a first temperature level to a network at a second, lower temperature level at the heat transfer station.

The advantage of the heat transfer station according to the invention is that said exergy difference between the district heating side and the heat customer side can be used for the generation of electrical energy by interposing a cyclic process, for example an Organic Rankine process (ORC process) with an organic working medium, a Stirling cycle, a steam power process, etc. Part of the high-temperature heat withdrawn from the district heating network is converted into electrical energy in the thermodynamic cycle. The condensation heat of the working medium feeds the heating network with low-temperature heat. Thus, the heat supply can be fully or partially realized via the thermodynamic cycle. The main benefit of the invention is the additional provision of electrical energy to the heat customer.

The heat transfer station according to the invention can be further developed such that a third heat exchanger can be provided for the direct transfer of heat from the first fluid to the second fluid. This has the advantage that part of the heat energy is transferred directly to the customer heat network and thus a protection of the heat supply against a failure of the thermodynamic cycle device is achieved.

A further development of the aforementioned development consists in that means for dividing the mass flow of the second fluid into a first part and a second part; Means for passing the first portion of the second fluid through the condenser and directing a second portion of the second fluid through the third heat exchanger; and means for merging the first part of the mass flow of the second fluid after passing through the condenser and the second part of the mass flow of the second fluid may be provided after passing through the third heat exchanger. The return temperature of the supplier heat network can by appropriate control of the cycle device on a constant level. The flow temperature in the customer heat network can be adjusted as required. If there is a higher heat requirement, the mass flow is reduced to the cycle.

According to another embodiment, the means for dividing the mass flow of the second fluid may be provided in a flow or in a return of the customer heat network, and they preferably comprise a three-way valve or a pump in a flow to the third heat exchanger. This corresponds in each case to advantageous examples for the arrangement and for the specific embodiment of these means.

Another development consists in that a fourth heat exchanger is provided for the direct transfer of heat from the first fluid to the working medium. As an alternative to power generation, a heat pump operating mode of the cycle processing device is made possible by the development. Heat pump operation offers the advantage for heat customers that the installed connection power can be lower.

A development of the aforementioned development consists in that means for diverting the working medium from a flow of the evaporator to the fourth heat exchanger, in particular in the form of a three-way valve or a solenoid valve; and means for operating the expansion machine are provided as the compressor. In this way, instead of the first heat exchanger, the working medium can be conducted to the fourth heat exchanger in order to absorb heat from the first fluid as the compressor during operation of the expansion machine.

A development of the aforementioned development is that the means for operating the expansion machine as a compressor include means for directing the working medium from the fourth heat exchanger to a low pressure side of the expansion machine operated as a compressor, in particular a first valve for blocking the connection between the evaporator and the High pressure side of the expansion machine and a bypass line with a second valve for establishing a connection between the fourth heat exchanger and the low pressure side of the expansion machine, and further means for directing the compressed working fluid from a high-pressure side of the expansion machine operated as a compressor to the condenser, in particular a fourth valve for blocking a connection between the low-pressure side of the expansion machine and the condenser and a bypass line with a third valve for establishing a connection between the high-pressure side of the expansion machine and the Capacitor. This provides preferred embodiments of said means.

According to another development, the heat transfer station can be designed such that the second heat-conducting fluid is passed completely through both the condenser and the third heat exchanger. In this case, the condenser flows through a large mass flow. This is advantageous for the electrical efficiency of the system.

Another development consists in that the heat transfer station with a third heat exchanger further comprises means for dividing the mass flow of the first fluid into a first part and a second part, in particular a three-way valve, and means for directing the first part of the first fluid to the third heat exchanger.

The aforementioned development can also be further developed in that a heat accumulator is provided in thermal contact with the second fluid. This allows a flattening of the temperature gradients of the second fluid entering the condenser. If the temperature of the second fluid is greater than the temperature of the heat accumulator, the second fluid is cooled, if it is smaller, it is heated.

The object according to the invention is furthermore achieved by a method according to claim 11.

The method according to the invention transfers heat from a supplier heat network with a first heat-conducting fluid to a customer heat network with a second heat-conducting fluid by means of a thermodynamic cycle device, in particular an ORC device, wherein the thermal cycle device comprises a first designed as an evaporator heat exchanger, an expansion machine, a generator coupled to the expander, a second heat exchanger configured as a condenser and a feed pump, the method comprising the following steps: preheating, evaporation and optionally additional overheating of the working medium while supplying heat from the first fluid to the first heat exchanger; Generating mechanical energy by relaxing the vaporized working medium with the expansion machine and at least partially converting the mechanical energy into electrical energy with the generator; Condensing the relaxed working medium and transferring heat energy from the relaxed working fluid to the second fluid with the second heat transfer fluid; and conveying the condensed working fluid under pressure increase to the evaporator with the feed pump. Before condensation can optionally take place a decompression of the relaxed working medium. After condensing, an optional subcooling of the condensed working medium can take place.

The advantages of the method and its developments correspond to those of the device according to the invention and its developments and are therefore not listed again here.

According to a development of the method according to the invention, the further step of the direct transfer of heat from the first fluid to the second fluid with a third heat exchanger is provided.

A development of the aforementioned development consists in that the following further steps are provided: splitting the mass flow of the second fluid into a first part and a second part; Passing the first portion of the second fluid through the condenser and passing a second portion of the second fluid through the third heat exchanger; and merging the first portion of the mass flow of the second fluid after passing through the condenser and the second portion of the mass flow of the second fluid after passing through the third heat exchanger.

According to another development, the method comprises the step of directly transferring heat from the first fluid to the working medium with a fourth heat exchanger.

Another development is that the second heat-conducting fluid is passed completely through both the condenser and the third heat exchanger.

According to another embodiment, at least partial feeding of the electrical energy into a network; and / or at least partially using the electrical energy for operating the customer heat network, in particular a customer-side heating system.

The cited developments can be used individually or combined as claimed suitable.

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

represents the Exergienutzung and the temperature profile in pure heating operation schematically.

Fig. 2

shows the corresponding exergy use with an integrated ORC process.

Fig. 3

shows a first embodiment of the heat transfer station according to the invention.

Fig. 4

shows a TQ diagram of the ORC process.

Fig. 5

shows a second embodiment of the heat transfer station according to the invention.

Fig. 6

illustrates cavitation avoidance by reducing the mass flow.

Fig. 7

shows a third embodiment of the heat transfer station according to the invention in a first operating mode.

Fig. 8

shows the third embodiment of the heat transfer station according to the invention in a second operating mode.

Fig. 9

shows a fourth embodiment of the heat transfer station according to the invention.

Fig. 10

shows a fifth embodiment of the heat transfer station according to the invention.

embodiments

First, the basic motivation of the invention with respect to the exergy will be presented below. The exergy refers to the part of the energy that can be completely transformed into any other form of energy, such as electrical energy. It is therefore the workable part of the energy. In contrast, anergy is not the workable part of an energy, a conversion into other forms of energy is not possible here. Even in an idealized process, heat energy can only partially be converted into mechanical energy.

errechnet. Hierbei ist T die Temperatur der Wärmequelle und T_U die Temperatur der Umgebung. Bei einem konventionellen Heizsystem wird die im Wärmestrom enthaltene Exergie durch Absenkung der Temperatur vernichtet, wie Fig. 1 verdeutlicht. Die Absenkung der Temperatur kann hierbei unterschiedliche Gründe haben. So kann eine Absenkung der Temperatur notwendig sein, um z.B. Temperaturgrenzen im Heizungssystem einzuhalten, dies gewährleistet beispielsweise die Wärmeübergabestation. Eine weitere Reduktion der Temperatur findet bei jeglicher Wärmeübertragung statt, sei es in der Wärmeübergabestation oder aber in der Heizung, welche z.B. einen Raum erwärmt. Wenn die Wärme sich auf Umgebungstemperatur reduziert hat, dann besitzt sie keine Arbeitsfähigkeit mehr und ist reine Anergie.A heat flow Q̇ consists of an exergy component Ė and an anergy component Ȧ, whereby the exergy component is calculated using the equation $$\dot{\mathrm{e}}=\left(\mathrm{1}-\frac{{\mathrm{T}}_{\mathrm{U}}}{\mathrm{T}}\right)\cdot \dot{\mathrm{Q}}$$

calculated. Here, T is the temperature of the heat source and T _{U is} the temperature of the environment. In a conventional heating system, the exergy contained in the heat flow is destroyed by lowering the temperature, such as Fig. 1 clarified. The lowering of the temperature can have different reasons. So can one Lowering the temperature may be necessary, for example to comply with temperature limits in the heating system, this ensures, for example, the heat transfer station. A further reduction of the temperature takes place with any heat transfer, be it in the heat transfer station or in the heater, which, for example, heats a room. When the heat has reduced to ambient temperature, it no longer has working capacity and is pure anergy.

In contrast, the integration of a thermodynamic cycle into the heating system (see Fig. 2 ) the reuse of part of the exergy contained in the heat flow in the form of electrical energy. Although the energy flow, which is converted into electrical energy, is no longer available for heating, it can be compensated for by a slight increase in the heat input into the ORC process. Due to low prices of the energy sources and thus the generated thermal energy compared to the reference prices for electrical energy, this is economically interesting, especially in the field of housing / small consumers.

Fig. 3 shows in a first embodiment of the invention, the simplest realization of the power-generating heat transfer station. The reference numbers used herein are also retained in the other figures for the other embodiments, if they are the same elements.

The first embodiment of the heat transfer station 1 according to the invention for transferring heat from a supplier heat network 10 with a first heat-conducting fluid to a customer heat network 20 with a second heat-conducting fluid comprises a thermodynamic cycle device 30 with a working medium (for example water or steam), in particular an ORC device with an organic working fluid, wherein the thermodynamic cycle device 30 comprises: a first heat exchanger configured as an evaporator 31 for evaporation and optionally additional preheating and / or overheating of the working medium with the supply of heat from the first fluid, an expansion machine 32 for generating mechanical energy by relaxing the evaporated working medium, one with the expansion machine coupled generator 33 for at least partially converting the mechanical energy into electrical energy, a second heat exchanger configured as a condenser 34 for condensing and optionally pre-dicing and / or additional subcooling of the expanded working medium and transferring heat energy from the expanded working medium to the second fluid, and a Feed pump 35 for conveying the condensed working fluid under pressure increase to the evaporator. The feed pump is operated by a motor 36. In addition, a pump 21 is provided in the heating circuit of the customer heat network, with the second fluid (for example, water) is promoted.

For the sake of clarity, a simplified representation of the district heating network 10, the ORC process 30 and the heating network 20 is selected. In the evaporator 31, liquid working medium is evaporated with heat input, expanded in the expansion machine 32 (e.g., screw expander, turbine), and liquefied at a lower pressure level. During the liquefaction in the condenser 34 heat is released from the working fluid to the heating water network and thereby reaches the required flow temperature. Via a shaft, the expansion machine 32 is coupled to the generator 33, which converts the mechanical energy into electrical energy. This can both be fed into a network, as well as used to cover the domestic needs of the heating system. The circuit is closed by the feed pump 35 increases the pressure of the working medium to the evaporation pressure and promotes it again in the evaporator 31. The integration of a thermodynamic cycle 30 in a heat transfer station 1 thus offers the possibility of a decentralized cogeneration in heat consumers. In the case of larger heat transfer stations, a modular design enables the parallel operation of multiple plants in one stack. In this way, a better partial load behavior and increased flexibility can be achieved.

The combination of a heat transfer station with a thermodynamic cycle, however, involves the problem that the ORC can only use part of the temperature gradient between district heating supply and return. This is due to the fact that the pinch point between the temperature of the heat source and the temperature of the working medium limits the heat absorption, like the TQ diagram of the ORC process in Fig. 4 clarified. Shown here are the temperature profiles of the fluids in the district heating network, in the heating network, as well as in the ORC process. Here, Q̇ _{max, ORC is} the maximum amount of heat that the ORC can absorb, with Q̇ _{requirement, customer} is the heat demand of the building. Pinch point (also called Zwickpunkt or point of least graveness) is called in the thermodynamic process engineering the point of the smallest temperature difference between two media, which transfer heat via one or more heat exchangers.

In addition, the heating power in the first embodiment is after Fig. 3 depending on the operation of the ORC 30. In case of failure of the thermodynamic process 30, the heat supply of the heating network 20 is no longer possible because no heat is decoupled via the capacitor 34. Another problem arises from the susceptibility of the working medium feed pump 35 to cavitation. Arrives within a short time a large amount of cold water in the condenser 34, for example, suddenly occurring heat demand, the pressure in the condenser 34 drops. If this falls below the prevailing temperature of the working medium boiling pressure below, it comes to cavitation, ie the local emergence of vapor bubbles in the condensate in the inlet and inlet to the feed pump 35, which then coincide again. Due to the associated pressure waves damage to the wheels of the feed pump 35, in addition, the resulting steam leads to the collapse of the funded volume flow, which then leads to the immediate stoppage of the cycle 30.

The patent DE 10 2009 053 390 B3 "Thermodynamic machine and method for its operation" describes a device and a method for avoiding cavitation in a thermodynamic cycle, which is particularly advantageous when using air condensers. In this case, an additional pressure is impressed on the working medium by adding a non-condensing gas in the condenser. Since this is equivalent to a larger flow height of the pump, increases in the pump inlet, the distance of the actual pressure to the boiling pressure. In return, this reduces the pressure difference across the expander and thus the electrical output Power. Since in condensation against water, the pressure difference across the expansion machine is relatively low, this solution is disadvantageous for the present application.

However, these disadvantages can be avoided by the further embodiments shown below as well as preferred combinations thereof.

The heating operation is in the second embodiment 2 after Fig. 5 regardless of the operation of the cycle. A variable part of the heat is absorbed by the cycle, while the rest is transmitted via a third heat exchanger 40 directly into the heating network 20. As an alternative to the 3-way valve 22, a further pump in the heating network flow to the third heat exchanger 40 can be used to divide the mass flow. The pumps can continue to be arranged both in the forward and in the return of the heating network 20. In case of failure of the cycle, the entire amount of heat can be supplied via the third heat exchanger 40. An emergency operation is thus given sufficient dimensioning of the third heat exchanger 40. The return temperature of the district heating network can be maintained by appropriate control of the cycle at a constant level or below a required maximum temperature. In ORC mode, the temperature is slightly higher than when the ORC is off. The flow temperature in the heating network 20 is arbitrarily adjustable. If there is a higher heat requirement, the mass flow is reduced in the cycle. At constant inlet and outlet temperatures of the working medium, this results in a lower heat input to the ORC. This in turn means due to the constant mass flow in the district heating network 10, that the output temperature increases on the side of the district heating network 10. As a result, a greater temperature difference is present across the third heat exchanger 40, as a result of which the amount of heat transferred directly to the heating network 20 is increased. The system can be integrated into heating water networks, where the district heating network and the heating water network are separated from each other, as well as in networks in which there is only one common network. For integration into a mixed network, the third heat exchanger 40 is no longer needed because you can direct a partial flow of district heating water directly into the heating network.

This second embodiment also has improved functionality for avoiding cavitation damage. Here, the mass flow of the heating water through the condenser 34 via the 3-way valve 22 can be reduced. As Fig. 6 shows, thereby increases the temperature spread of the mass flow of water. The condensation temperature of the working fluid is impressed by the inlet temperature of the water, the temperature difference in the pinch point, and the mass flow and thus the temperature spread of the water. If the water-side inlet temperature rises, the condensation pressure of the working medium also increases. If the mass flow of the water decreases, the outlet temperature of the water increases. Since the heat exchanger surface remains constant, but the temperature difference between the working fluid and water increases, the working fluid is more supercooled. A larger subcooling effect in the feed pump flow as a larger flow height, since the distance of the actual pressure increases to the evaporation pressure at the pump inlet.

With the large temperature spread between district heat flow (e.g., 120 ° C) and reflux (e.g., 45 ° C), heat transfer in evaporator 34 quickly reaches its limits. Due to the pinch point between working fluid and fluid at the inlet to the first heat exchanger (evaporator), the cooling of the district heating return and thus the heat is limited.

Furthermore, this second embodiment allows 2 different modes of operation. A first mode of operation is for heating and power production. With average heat demand, the cycle runs parallel to the heat supply and part of the heat demand is covered by the heat of condensation. A small portion of the heat from the heating network 20 is converted via the expansion machine 32 and the generator 33 into electrical energy. A second operating mode serves as a pure heating operation. For this purpose, the cycle 30 is switched off and the entire heat required via the third heat exchanger 40 is supplied to the heating network 20 at very high heat demand. This mode of operation is similar to that of a conventional transfer station.

In the case of sensitive heat sources (eg geothermal heating plant), the return temperature is an important parameter in order to get as much heat as possible from the source and to increase the efficiency of the system. The third embodiment 3 according to Fig. 7 represents a further development of the second embodiment 2, by the correspondingly low temperatures in the district heating return can be achieved.

As an alternative to power generation is by the third embodiment 3 after Fig. 7 a heat pump operating mode of the ORC allows. For this purpose, the expander 32 is operated as a compressor 32 by the valve 54 is closed and the valve 53 is opened, so that the fluid flows on the low-pressure side in the expansion machine 32. Furthermore, the valve 55 is closed. Through the open valve 52, the compressed working fluid flows into the condenser 34, where it gives off heat to the heating network 20. Through the throttle 56, a pressure reduction takes place, which is associated with a reduction in the boiling temperature. By means of the third heat exchanger 40, a part of the heat energy is transmitted to the heating network 20 and so lowered the return temperature to a suitable area for the heat pump. Subsequently, the working medium can be passed via the 3-way valve 51 to the fourth heat exchanger 50, where it can be evaporated. This will continue to cool the district heating return.

Heat pump operation offers the advantage for heat customers that the installed connection power can be lower. This is due to the fact that the rated connection power is defined by a fixed spread between district heating flow and return and the area of the heat exchanger. Due to the additional cooling of the return line with a constant heat exchanger surface and constant mass flow, the actual heat input in heat pump operation is greater than the rated connection power. For operators of, for example, geothermal heating plants has the advantage that the regenerative heat source so more energy can be withdrawn. In addition, the higher thermal energy yield at low return temperatures can replace part of the peak load energy supply.

In ORC mode according to Fig. 8 This third embodiment 3 behaves analogously to the second embodiment 2. Here, the valves 54 and 55 are open, the 3-way valve 51 obstructs access to the fourth heat exchanger 50 and allows access to the first heat exchanger 31.

Through the valves 52, 53, 54, 55, a bypass of the expansion machine 32 is possible, thus the pressure drops and the heat supply to the heating network 20 can be realized via a natural circulation. Alternatively, the third heat exchanger 40 allow the bypass. In heat pump operation, low district heating return temperatures can be achieved. A limitation of the heating network flow temperature consists of the maximum condensation temperature plus the heat transfer coefficient. The use is possible with minor modifications in both separate and mixed heating circuits. The Kavitationsvermeidung is given here as for the second embodiment. The temperature spread of the evaporator is the same as in the second embodiment. With the large temperature spread between district heating supply and return, the heat transfer in the evaporator quickly reaches its limits. Due to the pinch point between working medium and fluid in the district heating pipe, the cooling of the district heating return and thus the heat supply to the ORC is limited.

Fig. 9 shows a fourth embodiment 4 of the heat transfer station according to the invention. In this fourth embodiment 4, means for dividing the mass flow of the first fluid into a first part and a second part in the form of a three-way valve, and means for directing the first part of the first fluid to the third heat exchanger 40 are provided. Furthermore, there is a heat accumulator 60 in thermal contact with the second fluid. In case of failure of the cycle, the entire amount of heat can be supplied via the third heat exchanger 40. An emergency operation functionality is thus given with sufficient dimensioning of the third heat exchanger 40. In ORC mode, the district heating return temperature is slightly higher than in the second embodiment 2. The flow temperature in the heating network can be adjusted as required. If (eg at peak load) there is an increased / increased heat demand, the mass flow is reduced to the cycle, thereby more heat at a higher temperature level via the third heat exchanger 40 is transmitted to the heating network 20. The heating network flow temperature is the same as in the second embodiment 2. The insert is with minor modifications both in separate and in mixed heating circuits possible. In the return of the heating network 20 is a thermal storage 60 (latent heat storage or a sensitive heat storage) are connected in front of the capacitor 34 as a thermal buffer. This allows a flattening of the temperature gradient of the entering into the condenser 34 heating water. With the large temperature spread between district heating supply and return, the heat transfer in the evaporator quickly reaches its limits. Due to the pinch point between working medium and fluid in the district heating pipe, the cooling of the district heating return and thus the heat supply is limited.

In the fifth embodiment 5 after Fig. 10 the condenser 34 of the ORC is always flowed through on the side of the heating network 20 with the coldest temperature and with a large mass flow, since the second heat-conducting fluid is passed completely through both the condenser 34 and the third heat exchanger 40. This is advantageous for the electrical efficiency of the system, since at a larger mass flow, a lower temperature difference in HeizwasserRücklauf sets. At a constant pinch point, a lower counterpressure to the expansion machine thus sets in (see FIG. 11), which leads to a higher electrical output. In case of failure of the cycle, the entire amount of heat can be supplied via the third heat exchanger 40. An emergency operation is thus given sufficient dimensioning of the third heat exchanger 40. Due to the heating of the heating network return in the condenser 34, the district heating return flow through the third heat exchanger 40 can not be cooled as far as in the second embodiment. This results in ORC operation, depending on the mode of operation, an increase in the district heating return temperature, for example, about 10 to 15 K. The flow temperature in the heating network 20 is arbitrarily adjustable. If there is heat demand, the mass flow is reduced in the cycle, thereby more heat is transferred at a higher temperature level via the third heat exchanger 40 directly to the heating network. The use is possible with minor modifications in both separate and mixed heating circuits. Cavitation avoidance: As in the fourth embodiment 4, a latent heat accumulator or a sensitive heat accumulator upstream of the condenser 34 can be connected in the return flow of the heating network as a thermal buffer. This allows a flattening of the temperature gradient of the in the condenser entering heating water. Temperature spread in the evaporator of the fifth embodiment 5 corresponds to that of the second embodiment 2.

In summary, the heat transfer station according to the invention has the following advantages and disadvantages. Advantages are a better utilization of the exergy used (with little additional heat output great additional benefits, see Fig. 2 ); less destruction of exergy when heat is transferred to heat consumers; Decentralized combined heat and power generation at the end user (electricity generating heating system); Use of different temperature variants and network types (mixed and separate circles); great flexibility in performance and operation, adaptable to growing heat network (can be run as a stack); and to increase the efficiency and the power factor of the overall system. A disadvantage is a slightly lower maximum heat supply for the heat customer to call and in the embodiments 1, 2, 4, 5, a slight to moderate increase in the temperature of the district heating return. In the embodiments with emergency function can be provided by a bypass of the ORC, so its shutdown, and a sufficient dimensioning of the third heat exchanger 40, the total connected load nevertheless.

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

Claims (15)

A heat transfer station for transferring heat from a supplier heat network with a first heat-conducting fluid to a customer heat network with a second heat-conducting fluid, comprising: a thermodynamic cycle device with a working medium, in particular an ORC device with an organic working medium, the thermodynamic cycle device comprising: a first heat exchanger designed as an evaporator for preheating, evaporating and optionally additionally overheating the working medium while supplying heat from the first fluid, an expansion machine for generating mechanical energy by relaxing the vaporized working medium, a generator coupled to the expander for at least partially converting the mechanical energy into electrical energy, a second heat exchanger designed as a condenser for condensing and optionally additional de-icing and / or optionally additional subcooling of the expanded working medium and transferring heat energy from the expanded working medium to the second fluid, and a feed pump for conveying the condensed working fluid under pressure increase to the evaporator. Heat transfer station according to claim 1, further comprising: a third heat exchanger for directly transferring heat from the first fluid to the second fluid. Heat transfer station according to claim 2, further comprising: Means for dividing the mass flow of the second fluid into a first part and a second part; Means for passing the first portion of the second fluid through the condenser and directing a second portion of the second fluid through the third heat exchanger; and Means for merging the first part of the mass flow of the second fluid after passing through the condenser and the second part of the mass flow of the second fluid after passing through the third heat exchanger. Heat transfer station according to claim 3, wherein the means for dividing the mass flow of the second fluid are provided in a supply line or in a return of the customer heat network and preferably comprise a three-way valve, a solenoid valve or a pump in a flow to the third heat exchanger. Heat transfer station according to one of claims 1 to 4, further comprising: a fourth heat exchanger for directly transferring heat from the first fluid to the working fluid. Heat transfer station according to claim 5, further comprising: Means for diverting the working fluid from a flow of the evaporator to the fourth heat exchanger, in particular in the form of a three-way valve or a solenoid valve; and Means for operating the expansion machine as a compressor. Heat transfer station according to claim 6, wherein the means for operating the expansion machine as a compressor include: Means for directing the working medium from the fourth heat exchanger to a low pressure side of the compressor operated expansion machine, in particular a first valve for blocking the connection between the evaporator and the high pressure side of the expansion machine and a bypass line with a second valve for establishing a connection between the fourth heat exchanger and the Low pressure side of the expansion machine, and Means for directly directing the compressed working fluid from a high-pressure side of the compressor-operated expansion machine to the condenser, in particular a fourth valve for blocking communication between the low-pressure side of the expansion machine and the condenser and a bypass line with a third valve for establishing communication between the high-pressure side of the expansion machine and the capacitor. Heat transfer station according to claim 2, wherein the heat transfer station is formed such that the second heat-conducting fluid is passed completely through both the condenser and the third heat exchanger. Heat transfer station according to claim 2 or 8, further comprising: Means for dividing the mass flow of the first fluid into a first part and a second part, in particular a three-way valve, and Means for directing the first portion of the first fluid to the third heat exchanger. The heat transfer station of claim 9, further comprising: a heat storage in thermal contact with the second fluid. A method for transferring heat from a supplier heat network with a first heat-conducting fluid to a customer heat network with a second heat-conducting fluid by means of a thermodynamic cycle device, in particular an ORC device, wherein the thermal cycle device comprises a first heat exchanger designed as an evaporator, an expansion machine, with the expansion machine coupled generator, a second heat exchanger configured as a condenser and a feed pump, and wherein the method comprises the following steps: Preheating, evaporation and optionally additional overheating of the working fluid with the supply of heat from the first fluid with the first heat exchanger; Generating mechanical energy by relaxing the vaporized working medium with the expansion machine and at least partially converting the mechanical energy into electrical energy with the generator; Condensing and optionally additional deheating and / or optionally additional subcooling of the relaxed working medium and transferring heat energy from the expanded working medium to the second fluid with the second heat exchanger; and Conveying the condensed working fluid with pressure increase to the evaporator with the feed pump. The method of claim 11, further comprising the step: directly transferring heat from the first fluid to the second fluid with a third heat exchanger. The method of claim 12, further comprising the steps of: Dividing the mass flow of the second fluid into a first part and a second part; Passing the first portion of the second fluid through the condenser and passing a second portion of the second fluid through the third heat exchanger; and Merging the first part of the mass flow of the second fluid after passing through the condenser and the second part of the mass flow of the second fluid after passing through the third heat exchanger. Method according to one of claims 11 to 13, with the further step: directly transferring heat from the first fluid to the working fluid with a fourth heat exchanger. The method of claim 12, wherein the second heat-carrying fluid is passed completely through both the condenser and the third heat exchanger.

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