EP3006682B1 - Device and method for operating a heating distribution station - Google Patents

Description

field of invention

The invention relates to a heat transfer station for transferring heat from a supplier heat network with a first heat-carrying fluid to a customer heat network with a second heat-carrying fluid. Furthermore, the invention relates to a method for transferring heat from a supplier heat network with a first heat-carrying fluid to a customer heat network with a second heat-carrying 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, with it being used in liquid or vapor form. The medium is pumped in thermally insulated pipelines in a constant circulation. Local heat refers to a corresponding transfer of heat for heating purposes over comparatively short distances, although 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 depend on the consumers with the highest required temperature level. In downtown Munich, for example, the temperature of the district heating flow is 130 °C in winter and 80 °C in summer. The return temperature must not exceed 45 °C. These temperatures belong to the parameters that are usually specified in the technical connection conditions of the respective utility company and must be adhered to by the operating mode and construction of the system. However, the majority of consumers require lower flow temperatures for their heating systems. In the case of residential buildings, the required flow temperature is the hot water supply usually at about 60 - 65 °C, and therefore, according to the prior art, the temperature must first be lowered by adding colder water. In this way, however, a large part of the theoretically usable potential (exergy) of the hot water is wasted, which is disadvantageous. According to the prior art, heat is thus transported at a high temperature level over long distances and then lowered to a low temperature level with the elimination of exergy.

The document EP 2 538 040 A1 discloses a combined heat and power plant and associated method. The document DE 10 2012 217 929 A1 discloses a combined heat and power plant and a method for operating a combined heat and power plant.

Description of the invention

The object of the invention is to overcome this disadvantage and to make better use of 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-carrying fluid to a customer heat network with a second heat-carrying 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: one as an evaporator trained first heat exchanger for preheating, evaporating and optionally additional superheating of the working medium by supplying heat from the first fluid, an expansion machine for generating mechanical energy by expanding the vaporized working medium, a generator coupled to the expansion machine for at least partially converting the mechanical energy into electrical energy Energy, designed as a condenser second heat exchanger for condensing the expanded working medium and transferring thermal energy from the expanded th working medium to the second Fluid, and a feed pump for delivering the condensed working medium under pressure increase to the evaporator. Optionally, the working medium can be deheated in the condenser before it condenses. Furthermore, the working medium can optionally be supercooled below the condensation temperature in the condenser after the condensation. The first heat-conducting fluid and the second heat-conducting fluid can be the same fluid. In the heat transfer station, heat is transferred from a network with a first temperature level to a network with a second, lower temperature level.

According to the invention, the heat transfer station is designed to use the electrical energy at least partially to operate the customer's heating network, in particular a customer's heating system.

The advantage of the heat transfer station according to the invention is that the said exergy difference between the district heating side and the heat customer side can be used to generate 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 extracted from the district heating network is converted into electrical energy in the thermodynamic cycle. The heat of condensation of the working medium feeds the heating network with low-temperature heat. In this way, the heat supply can be realized in whole or in part via the thermodynamic cycle process. 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 thermal energy is transferred directly to the customer's heating network, thus securing the heat supply against failure of the thermodynamic cycle device.

A 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 for passing a second portion of the second fluid through the third heat exchanger; and means for combining 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 may be provided. The return temperature of the supplier heating network can be kept at a constant level by appropriate control of the cyclic process device. The flow temperature in the customer heating network can be regulated as required. If there is a higher demand for heat, the mass flow to the cycle is reduced.

According to another development, the means for dividing the mass flow of the second fluid can be provided in a flow or in a return of the customer heating network, and they preferably include 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 design of these means.

Another development is 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 cyclic process device is made possible by the development. Heat pump operation offers heat customers the advantage that the installed connected load can be lower.

A further development of the previously mentioned development is that means for diverting the working medium from an inlet of the evaporator to the fourth heat exchanger, in particular in the form of a three-way valve or a solenoid valve; and means are provided for operating the expander as a compressor. In this way, the working medium can be routed to the fourth heat exchanger instead of to the first heat exchanger, in order to absorb heat from the first fluid there when the expansion machine is operated as a compressor.

A further development of the aforementioned further development is that the means for operating the expansion machine as a compressor include: means for directly conducting 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 directly conducting the compressed working medium 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 expander and the condenser and a bypass line with a third valve for establishing a connection between the high pressure kside of the expander and the condenser. This makes preferred configurations of the means available.

According to another development, the heat transfer station can be designed in such a way that the second heat-carrying fluid is conducted completely both through the condenser and through the third heat exchanger. A large mass flow flows through the condenser. This is advantageous for the electrical efficiency of the system.

Another development is that the heat transfer station with a third heat exchanger also includes 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 conducting the first part of the first fluid to the third heat exchanger.

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

The object of the invention is further 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-carrying fluid to a customer heat network with a second heat-carrying fluid by means of a thermodynamic cycle device, in particular an ORC device, the thermal cycle device having a first heat exchanger designed as an evaporator, an expansion machine, one with the expansion machine coupled generator, a second heat exchanger designed as a condenser and a feed pump, the method comprising the following steps: preheating, evaporating and optionally additional overheating of the working medium while supplying heat from the first fluid to the first heat exchanger; Generating mechanical energy by expanding the vaporized working medium with the expander and at least partially converting the mechanical energy into electrical energy with the generator; condensing the expanded working medium and transferring thermal energy from the expanded working medium to the second fluid with the second heat exchanger; and conveying the condensed working medium under pressure increase to the evaporator with the feed pump. Before condensing, the expanded working medium can optionally be deheated. After the condensation, the condensed working medium can optionally be supercooled.

According to the invention, the electrical energy is used at least partially to operate the customer's heating network, in particular a customer's heating system.

The advantages of the method according to the invention 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 directly transferring heat from the first fluid to the second fluid using a third heat exchanger is provided.

A development of the aforementioned development consists in the following further steps being provided: 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 combining 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 includes the step of directly transferring heat from the first fluid to the working medium using a fourth heat exchanger.

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

The developments mentioned can be used individually or, as claimed, can be suitably combined with one another.

Further features and exemplary embodiments as well as advantages of the present invention are explained in more detail below with reference to the drawings. It is understood that the embodiments do not exhaust the scope of the present invention. It is also understood that some or all of the features described below can also be combined with one another in other ways.

drawings

1

shows the use of exergy and the temperature profile in pure heating operation.

2

shows the corresponding use of exergy with an integrated ORC process.

3

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

4

shows a T-Q diagram of the ORC process.

figure 5

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

6

illustrates cavitation avoidance by reducing the mass flow.

7

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

8

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

9

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

10

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

embodiments

First of all, the basic motivation of the invention in relation to the exergy is presented below. Exergy describes the part of the energy that can be completely converted into any other form of energy, such as electrical energy. It is therefore the workable part of the energy. In contrast to this, anergy is the non-workable part of energy, conversion into other forms of energy is not possible here. Even in an idealized process, thermal energy can only be partially 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 Q consists of an exergy component Ė and an anergy component Ä, whereby the exergy component can be calculated using the equation $$\dot{\mathrm{E}}=\left(1-\frac{{\mathrm{T}}_{\mathrm{u}}}{\mathrm{T}}\right)\cdot \dot{\mathrm{Q}}$$

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 1 clarified. The lowering of the temperature can have different reasons. It may be necessary to lower the temperature, for example in order to comply with temperature limits in the heating system. This is ensured, for example, by the heat transfer station. A further reduction in temperature takes place with any heat transfer, be it in the heat transfer station or in the heating system, which heats up a room, for example. When the heat has reduced to ambient temperature, it no longer has the ability to work and is pure anergy.

In contrast, the integration of a thermodynamic cycle into the heating system (see 2 ) the further use of part of the exergy contained in the heat flow in the form of electrical energy. The energy flow, which is converted into electrical energy, is no longer available for heating, but it can be compensated for by slightly increasing the heat supply in the ORC process. Due to the low prices of the energy sources and thus of the thermal energy generated compared to the purchase prices for electrical energy, this is economically interesting, especially in the area of the housing industry/small consumers.

3 shows in a first embodiment of the invention the simplest realization of the power-generating heat transfer station. The reference symbols used here are also retained in the further figures for the other embodiments if the same elements are involved.

The first embodiment of the heat transfer station 1 according to the invention for transferring heat from a supplier heating network 10 with a first heat-carrying fluid to a customer heating network 20 with a second heat-carrying fluid comprises a thermodynamic cycle device 30 with a working medium (e.g. water or steam), in particular one ORC device with an organic working medium, wherein the thermodynamic cycle device 30 comprises: a first heat exchanger designed as an evaporator 31 for evaporating and optionally additional preheating and/or superheating of the working medium while supplying heat from the first fluid, an expansion machine 32 for generating mechanical Energy by expanding the vaporized working medium, a generator 33 coupled to the expansion machine for at least partially converting the mechanical energy into electrical energy, a second heat exchanger designed as a condenser 34 for condensing and optionally prior deheating and/or additional sub-cooling of the expanded working medium and transferring thermal energy from the expanded working medium to the second fluid, and a feed pump 35 for conveying the condensed working medium under pressure increase to the evaporator. The feed pump is driven by a motor 36 . In addition, a pump 21 is provided in the heating circuit of the customer heating network, with which the second fluid (water, for example) is conveyed.

For the sake of clarity, a simplified representation of the district heating network 10, the ORC process 30 and the heating network 20 is chosen. In the evaporator 31, liquid working medium is vaporized with the supply of heat, expanded in the expansion machine 32 (eg 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 the required flow temperature is thereby reached. The expansion machine 32 is coupled to the generator 33 via a shaft, which converts the mechanical energy into electrical energy. This can be fed into a network or used to cover the heating system's own requirements. The circuit is closed by the feed pump 35 increasing the pressure of the working medium to the evaporation pressure and pumping it back into the evaporator 31 . The integration of a thermodynamic cycle process 30 in a heat transfer station 1 thus offers the possibility of a decentralized combined heat and power generation for heat consumers. In the case of larger heat transfer stations, the parallel operation of several systems in a stack is made possible by a modular design. In this way, better part-load behavior and increased flexibility are achieved.

However, the combination of a heat transfer station with a thermodynamic cycle 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, as shown in the ORC process TQ diagram in 4 clarified. The temperature curves of the fluids in the district heating network, in the heating network and in the ORC process are shown there. Q̇ _max,ORC is the maximum amount of heat that the ORC can absorb, Q̇ _{requirement,customer} is the heat requirement of the building. In thermodynamic process engineering, the pinch point (also called pinch point or point of lowest degree) is the point of the smallest temperature difference between two media that transfer heat via one or more heat exchangers.

In addition, in the first embodiment, the heating performance is lower 3 depending on the operation of the ORC 30. In the event of a failure of the thermodynamic process 30, the heat supply to the heating network 20 is no longer possible, since heat is no longer extracted via the condenser 34. Another problem arises from the susceptibility of the working medium feed pump 35 to cavitation. If a large amount of cold water gets into the condenser 34 within a short time, for example when heat is suddenly required, the pressure in the condenser 34 drops. If the boiling pressure falls below the prevailing temperature of the working medium, cavitation occurs, i.e. local formation of vapor bubbles in the condensate in the inlet and inlet to the feed pump 35, which then collapse again. The resulting pressure waves damage the impellers of the feed pump 35, and the vapor produced also leads to the collapse of the volume flow being conveyed, which then leads to the cycle process 30 coming to an immediate standstill.

The patent specification 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, the working medium is subjected to additional pressure by adding a non-condensing gas in the condenser. Since this is synonymous with a higher flow height of the pump, the difference between the actual pressure and the boiling pressure increases in the pump inlet. In return, this reduces the pressure difference across the expansion machine and thus the electrical power output. Since the pressure difference across the expansion machine is relatively low when condensing against water, this solution is disadvantageous for the present application.

However, these disadvantages can be avoided by the further embodiments presented below and preferred combinations thereof.

The heating operation is 2 after in the second embodiment figure 5 independent of the operation of the cyclic process. A variable part of the heat is absorbed by the cyclic process, while the rest is transferred directly into the heating network 20 via a third heat exchanger 40 . As an alternative to the 3-way valve 22, another pump in the heating network flow to the third heat exchanger 40 can be used to split the mass flow. The pumps can also be arranged both in the flow and in the return of the heating network 20. If the cyclic process fails, the entire amount of heat can be supplied via the third heat exchanger 40 . An emergency operation functionality is thus given with adequate dimensioning of the third heat exchanger 40 . The return temperature of the district heating network can be kept at a constant level or below a required maximum temperature by appropriate control of the cycle process. In ORC mode, the temperature is slightly higher than when the ORC is switched off. The flow temperature in the heating network 20 can be regulated as required. If there is a higher demand for heat, the mass flow in the cyclic process is reduced. With constant input and output temperatures of the working medium, there is less heat input to the ORC. Due to the constant mass flow in the district heating network 10, this in turn means that the outlet temperature on the side of the district heating network 10 increases. As a result, there is a greater temperature difference 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 both in heating water networks in which the district heating network and heating water network are separate from one another and in networks in which there is only one common network. The third heat exchanger 40 is no longer required for integration into a mixed network, since a partial flow of the district heating water can be routed directly into the heating network.

This second embodiment also has improved functionality to prevent cavitation damage. Here, the mass flow of the heating water through the condenser 34 can be reduced via the 3-way valve 22 . As 6 shows, this increases the temperature spread of the water mass flow. The condensation temperature of the working medium is determined by the inlet temperature of the water, the temperature difference at the pinch point, and the mass flow and thus the temperature spread of the water. If the water-side inlet temperature increases, 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 transfer surface remains constant, but the temperature difference between the working medium and the water increases, the working medium is supercooled to a greater extent. Greater subcooling has the same effect as greater head in the feed pump flow, since the difference between the actual pressure and the evaporating pressure at the pump inlet increases.

With the large temperature difference between district heating flow (e.g. 120 °C) and return (e.g. 45 °C), the heat transfer in the evaporator 34 quickly reaches its limits. Due to the pinch point between the working medium and the fluid at the entrance to the first heat exchanger (evaporator), cooling of the district heating return and thus the supply of heat is only possible to a limited extent.

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

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

As an alternative to power generation, according to the third embodiment 3 7 a heat pump operating mode of the ORC enables. For this purpose, the expander 32 is operated as a compressor 32 in that the valve 54 is closed and the valve 53 is opened, so that the fluid flows into the expansion machine 32 on the low-pressure side. Furthermore, the valve 55 is closed. The compressed working medium flows through the open valve 52 into the condenser 34 where it gives off heat to the heating network 20 . The throttle 56 causes the pressure to drop, which is accompanied by a reduction in the boiling temperature. By means of the third heat exchanger 40, part of the thermal energy is transferred to the heating network 20 and the return temperature is thus reduced to a range suitable for the heat pump. The working medium can then be routed via the 3-way valve 51 to the fourth heat exchanger 50, where it can be evaporated. This further cools the district heating return.

Heat pump operation offers heat customers the advantage that the installed connected load can be lower. This is due to the fact that the nominal connected load is defined by a fixed spread between district heating flow and return as well as the area of the heat exchanger. Due to the additional cooling of the return with a constant heat transfer surface and constant mass flow, the actual heat supply in heat pump operation is greater than the nominal connected load. For operators of geothermal heating plants, for example, there is the advantage that more energy can be extracted from the regenerative heat source. Due to the higher yield of thermal energy low return temperatures, part of the provision of peak load energy can also be replaced.

In ORC operation according to 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 blocks access to the fourth heat exchanger 50 and allows access to the first heat exchanger 31.

The valves 52, 53, 54, 55 allow the expansion machine 32 to be bypassed, which means that the pressure losses are reduced and the heat can be provided to the heating network 20 via natural circulation. Alternatively, the third heat exchanger 40 can enable the bypass. In heat pump operation, low district heating return temperatures can be achieved. The heating network flow temperature is limited by the maximum condensation temperature plus the temperature of the heat exchanger. With minor modifications, it can be used in both separate and mixed heating circuits. The cavitation avoidance 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 difference between district heating flow and return, the heat transfer in the evaporator quickly reaches its limits. Due to the pinch point between the working medium and the fluid in the district heating line, the cooling of the district heating return and thus the heat supply to the ORC is only possible to a limited extent.

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 conducting the first part of the first fluid to the third heat exchanger 40 are provided. There is also a heat accumulator 60 in thermal contact with the second fluid. If the cyclic process fails, the entire amount of heat can be supplied via the third heat exchanger 40 . An emergency operation functionality is thus given with adequate dimensioning of the third heat exchanger 40 . In ORC operation, the district heating return temperature is slightly higher than in the second embodiment 2. The flow temperature in the heating network can be regulated as required. If (e.g. at peak load) there is an increased/increased demand for heat, the mass flow to the cycle process is reduced, as a result more heat is transferred at a higher temperature level to the heating network 20 via the third heat exchanger 40 . The heating network flow temperature is the same as in the second embodiment 2. With minor modifications, it can be used with both separate and mixed heating circuits. A heat accumulator 60 (latent heat accumulator or a sensitive heat accumulator) is connected in front of the condenser 34 as a thermal buffer in the return of the heating network 20 . This allows the temperature gradients of the heating water entering the condenser 34 to be flattened out. With the large temperature difference between district heating flow and return, the heat transfer in the evaporator quickly reaches its limits. Due to the pinch point between the working medium and the fluid in the district heating line, the cooling of the district heating return and thus the heat supply is only possible to a limited extent.

In the fifth embodiment 5 after 10 the condenser 34 of the ORC on the side of the heating network 20 is always flowed through with the coldest temperature and with a large mass flow, since the second heat-carrying fluid is passed completely both through the condenser 34 and through the third heat exchanger 40. This is advantageous for the electrical efficiency of the system, as a larger mass flow results in a lower temperature difference in the heating water return. With a constant pinch point, a lower back pressure to the expansion machine is set (see Fig. 11), which leads to a higher electrical output. If the cyclic process fails, the entire amount of heat can be supplied via the third heat exchanger 40 . An emergency operation functionality is thus given with adequate dimensioning of the third heat exchanger 40 . Due to the heating of the heating network return in the condenser 34, the district heating return cannot be cooled as much by the third heat exchanger 40 as in the second embodiment. Depending on the mode of operation, this results in an increase in the district heating return temperature in ORC operation, for example by around 10 to 15 K. The flow temperature in the heating network 20 can be regulated as desired. If there is a need for heat, the mass flow in the cyclic process is reduced, which means that more heat at a higher temperature level is transferred directly to the heating network via the third heat exchanger 40 transfer. With minor modifications, it can be used in both separate and mixed heating circuits. Cavitation avoidance: As in the fourth embodiment 4, a latent heat store or a sensitive heat store can be connected upstream of the condenser 34 as a thermal buffer in the return flow of the heating network. This enables the temperature gradients of the heating water entering the condenser to be flattened. 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. The advantages are better utilization of the exergy used (large additional benefit with little additional heat output, see 2 ); less destruction of exergy when heat is transferred to heat consumers; decentralized combined heat and power at the end user (electricity-generating heating system); Use of different temperature variants and network types (mixed and separate circuits); great flexibility in terms of performance and operation, adaptable to a growing heating network (can be designed as a stack); and increase the efficiency and power rating of the overall system. A disadvantage is a slightly lower maximum heat supply for the heat customer 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 an emergency function, the entire connected load can still be made available by bypassing the ORC, ie by switching it off, and by adequately dimensioning the third heat exchanger 40 .

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

Claims (15)

1. A heat transfer station (2, 3, 4, 5) for transferring heat from a supplier's heat network (10) including a first heat carrying fluid to a customer's heat network (20) including a second heat carrying fluid, comprising:

   a thermodynamic cyclic process device (30) including a working medium, in particular an ORC device including an organic working medium, the thermodynamic cyclic process device comprising:

   a first heat exchanger (31) configured as an evaporator (31) for preheating, evaporating and optionally additionally superheating the working medium while supplying heat from the first fluid,

   an expansion engine (32) for generating mechanical energy by expanding the vaporized working medium,

   a generator (33) coupled to the expansion engine for at least partially converting the mechanical energy into electric energy,

   a second heat exchanger (34) configured as a condenser (34) for condensing and optionally additionally deheating and/or optionally additionally supercooling the expanded working medium and transferring heat energy from the expanded working medium to the second fluid, and

   a feed pump (35) for feeding the condensed working medium to the evaporator while increasing the pressure;

   characterized in that

   the heat transfer station (2, 3, 4, 5) is configured to use the electric energy at least partially for operating the customer's heating network, in particular a heating system on the customer's side.
2. The heat transfer station according to claim 1, further comprising:
   a third heat exchanger (40) for directly transferring heat from the first fluid to the second fluid.
3. The heat transfer station according to claim 2, further comprising:

   means (22) for dividing the mass flow of the second fluid into a first portion and a second portion;

   means for passing the first portion of the second fluid through the condenser and for passing a second portion of the second fluid through the third heat exchanger; and

   means for combining 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.
4. The heat transfer station according to claim 3, wherein the means for dividing the mass flow of the second fluid are provided in a feed line or in a return line of the customer's heat network and preferably comprise a three-way valve, a solenoid valve or a pump in a feed line to the third heat exchanger.
5. The heat transfer station according to any one of claims 1 to 4, further comprising:
   a fourth heat exchanger (50) for directly transferring heat from the first fluid to the working medium.
6. The heat transfer station according to claim 5, further comprising:

   means (51) for diverting the working medium from a feed line of the evaporator to the fourth heat exchanger, in particular in the form of a three-way valve or a solenoid valve;

   and

   means (52, 53, 54, 55) for operating the expansion engine as a compressor.
7. The heat transfer station according to claim 6, wherein the means for operating the expansion engine as a compressor comprise:

   means (53, 54) for directly leading the working medium from the fourth heat exchanger (50) to a low-pressure side of the expansion engine (32) operated as a compressor, in particular a first valve (54) for blocking the connection between the evaporator and the high-pressure side of the expansion engine and a bypass line including a second valve (53) for establishing a connection between the fourth heat exchanger (50) and the low-pressure side of the expansion engine (32), and

   means (52, 55) for directly leading the compressed working medium from a high-pressure side of the expansion engine (32) operated as a compressor to the condenser (34), in particular a fourth valve (55) for blocking a connection between the low-pressure side of the expansion engine (32) and the condenser (34), and a bypass line including a third valve (52) for establishing a connection between the high-pressure side of the expansion engine (32) and the condenser (34).
8. The heat transfer station according to claim 2, wherein the heat transfer station is configured such that the second heat carrying fluid is passed entirely through both the condenser and the third heat exchanger.
9. The heat transfer station according to claims 2 or 8, further comprising:

   means (41) for dividing the mass flow of the first fluid into a first portion and a second portion, in particular a three-way valve, and

   means for leading the first portion of the first fluid to the third heat exchanger.
10. The heat transfer station according to claim 9, further comprising:
    a heat accumulator (60) in thermal contact with the second fluid.
11. A method for transferring heat from a supplier's heat network including a first heat-carrying fluid to a customer's heat network including a second heat-carrying fluid by means of a thermodynamic cycle device, in particular an ORC device, wherein the thermal cycle device comprises a first heat exchanger configured as an evaporator, an expansion engine, a generator coupled to the expansion engine, a second heat exchanger configured as a condenser, and a feed pump, and wherein the method comprises the following steps:

    preheating, evaporating and optionally additionally superheating the working fluid while supplying heat from the first fluid using the first heat exchanger;

    generating mechanical energy by expanding the vaporized working medium using the expansion engine and at least partially converting the mechanical energy into electric energy using the generator;

    condensing and optionally additionally deheating and/or optionally additionally supercooling the expanded working fluid and transferring heat energy from the expanded working fluid to the second fluid using the second heat exchanger; and

    feeding the condensed working medium to the evaporator while increasing the pressure using the feed pump;

    characterized by

    at least partially using the electrical energy to operate the customer's heating network, in particular a customer's heating system.
12. The method according to claim 11, comprising the further step of:
    directly transferring heat from the first fluid to the second fluid using a third heat exchanger.
13. The method according to claim 12, comprising the further steps of:

    dividing the mass flow of the second fluid into a first portion and a second portion;

    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

    combining 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.
14. The method according to any one of claims 11 to 13, comprising the further step of:
    directly transferring heat from the first fluid to the working medium using a fourth heat exchanger.
15. The method according to claim 12, wherein the second heat carrying fluid is passed entirely through both the condenser and the third heat exchanger.

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