DE102017202227A1 - Method for operating a heat pump system, heat pump system and power plant with a heat pump system - Google Patents

Abstract

The invention relates to a method for operating a heat pump system (1), in which a working fluid circulates within a directed working circuit (100) of the heat pump system (1), in which the working fluid is compressed by means of a compressor (20, ..., 25) and a condenser (4) is liquefied, in which a mass flow of the working fluid before the supply line to a first and second evaporator (31, 32) divided (102) and the first and second evaporator (31, 32) is supplied in parallel and wherein the Working fluid at a first evaporation pressure (411) in the first evaporator (31) and at a relation to the first evaporation pressure (411) reduced second evaporation pressure (412) in the second evaporator (32) is evaporated. According to the invention, the first evaporator (31) is thermally coupled to a first heat source (41) having a first heat source temperature and the second evaporator (32) is thermally coupled to a second heat source (42) having a lower second heat source temperature than the first heat source temperature The invention further relates to a heat pump system (1) and a power plant, which comprises a heat pump system according to the invention.

Description

The invention relates to a method for operating a heat pump system, a heat pump system with at least two evaporators and a power plant, in particular a gas-and-steam combined cycle power plant (abbreviated: CCPP) with a heat pump system according to the invention.

In heat pumps is absorbed by the evaporation of a working fluid, which circulates working fluid within the heat pump in a directed working cycle, by the evaporation of the working fluid, thermal energy, that is heat, taken from a heat source and delivered to a heat sink. In this case, the absorbed thermal energy is brought by means of a compressor to an elevated pressure level and then liquefied at an increased compared to an evaporation temperature condensing temperature. The greater the difference in magnitude (temperature swing) between the evaporating and condensing temperature of the working fluid, the lower the efficiency of the heat pump. The efficiency of a heat pump is measured by means of a Coefficient of Performance (COP), which is best given by the reciprocal efficiency of a Carnot process.

For example, if there is an evaporation temperature of 40 ° C and a temperature of 100 K, the coefficient of performance is 4.13. Here, the liquefaction of the working fluid takes place at a liquefaction temperature of 140 ° C.

Consequently, in order to achieve a high efficiency of the heat pump, the evaporation temperature, that is, the temperature at which the evaporation of the working fluid takes place, should be as high as possible. Furthermore, it is advantageous if the transmission of the thermal energy from the heat source to the working fluid takes place with the smallest possible difference between the temperature of the heat source and the evaporation temperature.

In particular, by means of a known heat pump or a known heat pump system, a plurality of different temperature-controlled heat sources can not typically be used efficiently with respect to their heat content. The majority of the heat of such heat sources therefore remains unused in the prior art.

One reason for the said inadequate thermal utilization of heat sources of different temperature is that heat pumps used in the prior art have no temperature slippage in the heat absorption from the heat sources (heat source side). That is, the evaporation of the working fluid of the heat pump is typically isothermal and thus without any significant change in the evaporation temperature.

From the DE 10 2014 213 542 A1 a method according to the preamble of present claim 1 is known.

The present invention has for its object to improve the heat recovery or heat recovery from a plurality of different heat sources.

The object is achieved by a method having the features of independent claim 1, by a heat pump system having the features of independent claim 13 and by a power plant having the features of independent claim 19. In the dependent claims advantageous refinements and developments of the invention are given.

In the method according to the invention for operating a heat pump system, a working fluid circulates within a directed working cycle of the heat pump system. The working fluid is compressed by means of a compressor and liquefied by means of a condenser. According to the invention, a mass flow of the working fluid is split before the feed line to at least a first and second evaporator and fed in parallel to at least the first and second evaporator, wherein the working fluid at a first evaporation pressure in the first evaporator and at a second evaporation pressure in the second evaporator reduced compared to the first evaporation pressure evaporated.

Furthermore, according to the invention, the first evaporator is thermally coupled to a first heat source having a first heat source temperature and the second evaporator is thermally coupled to a second heat source having a lower second heat source temperature than the first heat source temperature.

In other words, the mass flow of the working fluid is divided before the supply line to the first and second evaporator at least in a first and second partial mass flow, wherein the first partial mass flow to the first and the second partial mass flow directed to the second evaporator.

According to the invention, the evaporation of the working fluid is carried out in two parallel process steps, that is, the evaporation of the working fluid takes place in two with respect to the mass flow of the working fluid connected in parallel evaporators. Here, according to the invention, the first evaporator has a relation to the second evaporator increased evaporation pressure on. Due to the second evaporation pressure, which is lower than the first evaporation pressure, the evaporation of the working fluid by means of the second evaporator takes place at a second evaporation temperature, which is reduced compared to a first evaporation temperature in the first evaporator.

If the first heat source is conducted to the first evaporator, that is to say thermally coupled thereto, and the second heat source is led to the second evaporator, that is to say thermally coupled thereto, then the thermal energy of the heat sources is used in cascade. The heat sources are thus thermally coupled in series with the evaporators, with the temperature of the heat sources (heat source temperature) decreasing in series with the evaporators. It is therefore possible for the respective evaporation temperature, that is to say the temperature at which the evaporation of the working fluid in the first and / or second evaporator takes place, to be adapted to the heat source temperature of the heat source thermally coupled to the respective evaporator.

In other words, according to the invention, each evaporator is thermally coupled to a different heat source. The evaporators are connected in parallel with respect to the working cycle. This results in a multi-stage, at least two-stage evaporation of the working fluid at different pressure levels.

As a result of the multistage, at least two-stage evaporation according to the invention, a temperature sliding on the heat source side of the heat pump system is consequently made possible. As a result, a plurality of different temperature-controlled heat sources (first and second heat source) can be efficiently used thermally with the heat pump system, without reducing the efficiency of the heat pump system. In other words, with the present invention, it becomes possible to efficiently integrate a plurality of heat sources at different temperature levels.

The heat pump system according to the invention comprises at least one compressor, a condenser and at least one first and second evaporator, wherein the heat pump system has a directed working circuit for a circulating working fluid. According to the invention, the working cycle of the heat pump system is designed to divide a mass flow of the working fluid upstream of a supply line of the working fluid to the first and second evaporators and to supply them in parallel to the first and second evaporators, wherein the first evaporator has a first evaporation pressure and the second evaporator has a lower pressure than the first evaporation pressure having second evaporation pressure.

According to the invention, the heat pump installation further comprises at least one first and second heat source, the first heat source having a first heat source temperature and the second heat source having a second heat source temperature lower than the first heat source temperature, and the first heat source thermally with the first evaporator and the second heat source thermally with the second Evaporator is coupled.

By means of the heat pump system according to the invention, a Rankine heat pump process is made possible which has a temperature slide on the heat source side. Furthermore, heat sources at different temperature levels can be efficiently integrated into a heat pump cycle. There are similar and the same advantages to the already mentioned inventive method.

The power plant according to the invention comprises a heat pump system according to the present invention.

There are similar and equivalent advantages to the process of the invention and the heat pump system according to the invention.

Preferably, the heat sources are designed as different temperature-controlled waste heat sources of the power plant.

According to an advantageous embodiment of the invention is used as the first and second heat source in each case a different waste heat of a power plant, in particular a gas and steam combined cycle power plant (combined cycle power plant).

This can advantageously more waste heat of the power plant, which is obtained for example by the operation of the power plant, be recovered. Furthermore, advantageously cooling device can be saved, resulting in lower investment costs. This is particularly advantageous for a gas and steam combined cycle power plant, as it typically has a plurality of different waste heat sources.

In this case, it is particularly preferred if waste heat of a flue gas is used as the first heat source and waste heat of a transformer cooling is used as the second heat source.

This is the case because the said heat sources typically have a high temperature with respect to other waste heat sources.

In an advantageous embodiment of the invention, at least for one of the heat sources waste heat of a flue gas, transformer cooling, transmission cooling, engine cooling, condenser cooling a housing of a heat recovery steam generator, a gas turbine acoustic hood, a generator cooling and / or a lubricating medium supply is used.

Advantageously, a plurality of waste heat sources of a power plant for recovering thermal energy can thereby be used. This increases the efficiency of the power plant.

According to an advantageous embodiment of the invention, the working fluid is supplied in parallel to the supply line to the first evaporator a first expansion valve and before the supply line to the second evaporator a second expansion valve.

In other words, a relaxation or expansion of the working fluid by means of the first and second expansion valve preferably takes place in parallel. For this purpose, the mass flow of the working fluid before the first and second evaporator and before the first and second expansion valve is divided into a first and second partial mass flow, wherein the first partial mass flow to the first and the second partial mass flow to the second expansion valve is passed. By means of the first and second expansion valve, the working fluid is brought to the first and second evaporation pressure. In other words, by means of the first expansion valve the first evaporation pressure in the first evaporator and by means of the second expansion valve the second evaporation pressure in the second evaporator is set.

According to a preferred embodiment of the invention, a first and a second compressor is used to compress the working fluid, wherein the working fluid discharged from the first evaporator is supplied to the first compressor and the working fluid discharged from the second evaporator to the second compressor.

In other words, the compression of the working fluid, as already the evaporation of the working fluid, preferably in parallel. The mass flow of the working fluid is divided, passed to a first and second expansion valve, then fed to a first and second evaporator and introduced after the first and second evaporator in the respective input of the first and second compressor. Consequently, the expansion, evaporation and compression of the working fluid by means of the two partial mass flows occur in parallel.

It is particularly preferred for the first and the second compressor to use a common motor shaft.

This increases the efficiency of compaction.

According to a particularly preferred embodiment of the invention, a common compressor is used for compression, wherein the discharged from the first and second evaporator working fluid is supplied to the common compressor.

In other words, the compression of the working fluid takes place in one process step, that is, in a common compressor. As a common compressor in this case a compressor is referred to, in which the partial mass flows of the first and the second evaporator are introduced to compress the working fluid. This results in an efficient and preferred compression of the working fluid within the working cycle of the heat pump system.

Preferably, the working fluid discharged from the first evaporator is directed to a first check valve before the supply line to the common compressor, and the working fluid discharged from the second evaporator is led to a second check valve upstream of the supply line to the common compressor.

This advantageously ensures that the various pressure levels in the first and second evaporators do not lead to a (pressure) setback.

Particularly preferred is a common compressor, which is designed as a multi-stage turbocompressor. In this case, the working fluid discharged from the first evaporator is supplied to a first compressor stage of the turbocompressor and the working fluid discharged from the second evaporator to a second compressor stage of the turbocompressor.

The partial mass flows of the working fluid are thus brought together again via the compressor stages of the turbocompressor to a mass flow. As a result, the mass flow of the working fluid inside the turbocompressor increases from the compressor stage to the compressor stage. Advantageously, can be dispensed with a use of mass flow controllers, since the control of the mass flow can be done by means of the compressor stages of the turbocompressor.

According to an expedient embodiment of the invention, a control of a Part mass flow of the discharged from the first and / or second evaporator working fluid before the supply line to the common compressor.

This ensures, in particular when using a common compressor, that the working fluid is sucked out of the first and second evaporator and supplied to the common compressor. The regulation can be done by means of mass flow controllers.

According to an advantageous embodiment of the invention, the discharged from the first and second or the common compressor working fluid is passed to the condenser.

In other words, the liquefaction of the working fluid is advantageously carried out within the working cycle of the heat pump system in a common condenser.

In general, the working cycle of the heat pump system can be designed such that the working fluid discharged from the first evaporator is directed to the first compressor and the working fluid discharged from the second evaporator to the second compressor. Furthermore, the working cycle of the heat pump system can be designed to direct the working fluid discharged from the first and second evaporators to the common compressor, a multi-stage turbocompressor being provided in particular for the common compressor.

Furthermore, the heat pump system may comprise at least one expansion valve and / or at least one mass flow controller for controlling the mass flow and / or for controlling the partial mass flows.

• 1 ein schematisches Schaltbild einer Wärmepumpenanlage mit fünf Verdichtern, fünf Verdampfern und fünf verschiedenen Wärmequellen, wobei die Verdichter und die Verdampfer bezüglich eines Massenstromes eines Arbeitsfluids der Wärmepumpenanlage parallel geschaltet sind;
• 2 ein schematisches Schaltbild einer Wärmepumpenanlage mit einem gemeinsamen Verdichter, fünf Verdampfern und fünf verschiedenen Wärmequellen, wobei die Verdampfer bezüglich eines Massenstromes eines Arbeitsfluids der Wärmepumpenanlage parallel geschaltet sind;
• 3 ein weiteres schematisches Schaltbild einer Wärmepumpenanlage mit einem Turboverdichter, fünf Verdampfern und fünf verschiedenen Wärmequellen, wobei die Verdampfer bezüglich eines Massenstromes des Arbeitsfluids der Wärmepumpenanlage parallel geschaltet sind; und
• 4 ein Druck-Enthalpie-Diagramm einer Ausgestaltung des erfindungsgemäßen Verfahrens.

Further advantages, features and details of the invention will become apparent from the embodiments described below and with reference to the drawings. Showing:

• 1 a schematic diagram of a heat pump system with five compressors, five evaporators and five different heat sources, the compressor and the evaporator are connected in parallel with respect to a mass flow of a working fluid of the heat pump system;
• 2 a schematic diagram of a heat pump system with a common compressor, five evaporators and five different heat sources, the evaporators are connected in parallel with respect to a mass flow of a working fluid of the heat pump system;
• 3 a further schematic diagram of a heat pump system with a turbocompressor, five evaporators and five different heat sources, the evaporators are connected in parallel with respect to a mass flow of the working fluid of the heat pump system; and
• 4 a pressure-enthalpy diagram of an embodiment of the method according to the invention.

Similar, equivalent or equivalent elements may be provided with the same reference numerals in the figures.

All numerical values and / or temperature values given below are exemplary and do not limit the scope of protection of the present invention. Furthermore, the explicitly used number of evaporators, compressors, expansion valves, check valve, heat sources and / or other elements is exemplary and does not limit the scope of the present invention.

In general, relative terms, such as for example after a condenser or generally after or before an element of a heat pump system, with respect to a directed working cycle of the heat pump system to understand. In other words, the working cycle of the heat pump system has a direction with respect to which a method step can take place after or in front of an element.

In 1 schematically is a circuit diagram of a heat pump system 1 shown. The heat pump system 1 includes five evaporators 31 , ..., 35 and five compressors 21 ..., 25th Furthermore, the heat pump system 1 five expansion valves 51 , ..., 55 on. For the liquefaction of a within a directed working cycle 100 the heat pump system 1 circulating working fluid is a liquefier 4 intended. The five compressors 21 , ..., 25 are on a common motor shaft 10 arranged. In other words, the five compressors 21, ..., 25 are operated by means of a motor.

Before the supply of the working fluid to the five evaporators 31, ..., 35, the mass flow is divided into five partial mass flows (indicated by the reference numeral 102 ), with each evaporator 31 , ..., 35 exactly one of the five partial mass flows is supplied.

Each of the five evaporators 31 , ..., 35 of the heat pump system 1 is each thermally coupled to a heat source 41, ..., 45 associated with it. For example, the first heat source 41 is at least partially the waste heat of a flue gas, the second heat source 42 at least partially the waste heat of a transformer cooling, the third heat source 43 at least partially the waste heat of an engine cooling and the fourth heat source 44 at least partially the waste heat of a transmission cooling. The abovementioned waste heat sources are typically present in power plants, in particular combined cycle power plants.

In this case, for example, the first heat source occurs 41 with a heat source temperature (heat source temperature) of 90 ° C with the first evaporator 31 in thermal contact. At least part of the working fluid evaporates in the first evaporator 31 under a recording of thermal energy from the first heat source 41 , By this release of thermal energy to the working fluid, the temperature of the first heat source decreases 41 , for example at 75 ° C. The second heat source 42 has a heat source temperature of 80 ° C and is thermal with the second evaporator 32 coupled. The third heat source 43 has a heat source temperature of 65 ° C and is thermal with the third evaporator 33 coupled. The fourth heat source 44 has a heat source temperature of 55 ° C and is thermal with the fourth evaporator 34 coupled. Another fifth heat source 45 is with the fifth evaporator 35 thermally coupled. Thus, the heat sources 41 , ..., 45 a different temperature or a different temperature level.

The thermal energy of the heat sources 41 , ..., 45 is theoretically absorbed by the working fluid only by its evaporation (latent heat). In real heat pump system 1 an additional slight increase in the temperature of the working fluid, for example by 5 K (heat transfer rate) can take place.

After cooling the first heat source 41 through the first evaporator 31 has the first heat source 41 a temperature of 75 ° C on.

After cooling the second heat source 42 through the second evaporator 32 has the second heat source 42 a temperature of 65 ° C on. Analogously, the third, fourth and fifth heat source 43 . 44 . 45 according to their respective associated evaporators 33 . 34 . 35 each at a reduced temperature.

The evaporation of the working fluid and thus the heat transfer from the heat sources 41 , ..., 45 on the working fluid of the heat pump system 1 takes place in at least five evaporation steps 411 , ..., 415, wherein the first evaporation step 411 in the first evaporator 31 an evaporation temperature of 70 ° C, the second evaporation step 412 in the second evaporator 32 an evaporation temperature of 60 ° C, the third evaporation step 413 in the third evaporator 33 an evaporation temperature of 50 ° C and the fourth evaporation step 414 in the fourth evaporator 34 has an evaporation temperature of 40 ° C. Due to the multi-stage evaporation at different pressure and temperature levels, the coefficient of performance of the heat pump system 1 , despite the use of different tempered heat sources 41 , ..., 45, increased.

For relaxation or expansion of the working fluid, at least one of the expansion valve is in each case within a partial mass flow 51 , ..., 55 and at least one of the compressors 21 , ..., 25 arranged.

In other words, the mass flow of the working fluid is after the condenser 4 divided into the five partial mass flows 102, wherein a first partial mass flow to the first expansion valve 51 , a second partial mass flow to the second expansion valve 52 , a third partial mass flow to the third expansion valve 53 , a fourth partial mass flow to the fourth expansion valve 54 and finally, a fifth partial mass flow to the fifth expansion valve 55 to be led.

After the expansion valves 51 , ..., 55, the partial mass flows in each case to one of the evaporator 31 , ..., 35 and then each to one of the five compressors 21 , ..., 25 led. After the compression of the working fluid by means of the compressor 21 , ..., 25 the sub-mass flows are combined again into a common mass flow of the working fluid and the condenser 4 passed, whereby the directed working cycle of the working fluid of the heat pump system 1 closes. By means of the condenser 4 becomes that of the working fluid from the heat sources 41 , ..., 45 absorbed thermal energy to one with the condenser 4 thermally coupled heat sink 14 delivered or provided for further use. In other words, the heat sink 14 be designed as a heat consumer.

2 shows a schematic diagram of a heat pump system 1 with five evaporators 21 , ..., 25 and a common compressor 20 , Furthermore, the heat pump system 1 for liquefying the working fluid 4 and thus to deliver the heat to a heat sink 14 a liquefier 4 on.

As already under 1 at least a part of the thermal energy of the heat sources is described 41 , ..., 45 by means of five parallel evaporators 31 , ..., 35 by the at least partial evaporation of the working fluid within the five evaporators 31 , ..., 35 on the working fluid transfer. For every heat source 41 , ..., 45 is one of the evaporators 31 , ..., 35 provided.

In contrast to 1 will be in the in 2 illustrated embodiment, a common compressor 20 used for the compression of the working fluid. Here are the five of the evaporators 31 , ..., 35 outgoing partial mass flows of the working fluid to the common compressor 20 passed or already before the common compressor 20 again merged into a common mass flow of the working fluid, which to the common compressor 20 is directed.

To avoid (pressure) setbacks, due to different pressure levels in the individual evaporators 31, ..., 35, flow through the individual partial mass flows each have a check valve 61 ..., 65th Furthermore, a regulation of the partial mass flows by means of at least four mass flow controllers 71, ..., 74 expedient. The mass flow controllers guarantee this 71 , ..., 74, that the working fluid from each of the five evaporators 31 , ..., 35 sucked off and to the common compressor 20 is directed.

3 shows a particularly preferred embodiment of the present invention, in which a heat pump system 1 a common compressor 20 includes, which as a turbocompressor 20 is trained.

As already under 1 and or 2 described, the evaporation takes place within the heat pump system 1 circulating working fluid in several parallel evaporation steps 411 , ..., 415, with the individual evaporation steps 411 , ..., 415 each by means of an evaporator 31 , ..., 35. The individual evaporators 31 , ..., 35 are therefore as already in 1 and or 2 shown connected in parallel with respect to the mass flow of the working fluid. To avoid (pressure) setbacks are in turn within the individual partial mass flows check valve 61 , ..., 65. The expansion or expansion of the working fluid is in turn carried out by means of a plurality of expansion valves 51, ..., 55. The breakdown 102 the mass flow of the working fluid in the partial mass flows takes place as already in 1 and or 2 illustrated and explained after the condenser 4 ,

The individual partial mass flows are each in a compressor stage 201 , ..., 205 of the multi-stage turbocompressor 20 directed. Here, the line of the partial mass flows to the individual compressor stages 201 , ..., 205 after the evaporators 31, ..., 35 and after the check valves 61 ..., 65th For example, one from the first evaporator 31 outgoing first partial mass flow to the first check valve 61 and then to the first compressor stage 201 the turbo compressor 20 guided. A second partial mass flow, starting from the second evaporator 32 , becomes the second check valve 62 and then to the second compressor stage 202 the turbo compressor 20 directed. Here are the individual compressor stages 201, ..., 205 of the compressor 20 arranged on a common motor shaft 10.

In 4 an exemplary pressure-enthalpy diagram of an embodiment of the method according to the invention is shown.

This shows the ordinate 114 the respective prevailing pressure p of the working fluid within the working cycle of the heat pump system 1 at. At the abscissa 116 the specific enthalpy h of the working fluid associated with the pressure p is plotted.

A phase boundary in the pressure-enthalpy diagram is a boiling line 124 and a dew line 126 certainly. The evaporation of the working fluid takes place in the illustrated idealized manner along isotherms 112 , where the isotherms 112 between the boiling line 124 and the dew line 126 approximately parallel to the abscissa 116 run. Further, the diagram in FIG 4 a plurality of isentropes 110 ,

Starting from the condenser 4 the heat pump system 1 First, an isothermal liquefaction takes place 230 of the working fluid under a release of thermal energy to a heat sink 14. This causes a condition 2 of the working fluid in a state 3 above. The state is a point of the working fluid in the pressure-enthalpy diagram. In the illustrated embodiment, the liquefaction takes place 230 at a liquefaction temperature of 130 ° C.

This is followed by a reduction 340 of pressure (relaxation 340 ), for example by means of expansion or expansion of the working fluid. The state 3 goes into a plurality of states 4 above. The expansion or relaxation 340 of the working fluid can, as already to the 1 to 3 explained in parallel.

The evaporation of the working fluid takes place in parallel evaporation steps 411 , ..., 415 by means of a plurality of parallel connected evaporators 31 ..., 35th In this case, the evaporation steps take place 411 , ..., 415 approximately or ideally isothermal. The conditions 4 of the working fluid thus go over the evaporations 411 , ..., 415 in a plurality of states 1 above. Furthermore, more than the five illustrated evaporation steps 411 , ..., 415.

Subsequently, a compression takes place 120 that is, an increase in the pressure of the working fluid affecting the conditions 1 the working fluid to the state 2 returns. This will make the directed work cycle 100 closed the working fluid. The compression 120 of the working fluid can in turn by means of parallel compressor 21 , ..., 25 or by means of a common compressor 20 respectively.

In particular, all working fluids known from the prior art can be used as working fluids of the heat pump system. Furthermore, working fluids containing at least one of 1,1,1,2,2,4,5,5,5-nonafluoro-4- (trifluoromethyl) -3-pentanones (trade name Novec ™ 649), perfluoromethylbutanone, 1-chloro 3,3,3-trifluoro-1-propenes, cis-1,1,1,4,4,4-hexafluoro-2-butenes and / or cyclopentane, are advantageous. In particular, working fluids comprising at least one fluoroketone are advantageous.

An advantage of the said working fluids is the technical handling. They are characterized by good environmental compatibility and by their safety properties, such as no flammability or a very low global warming potential. In general, the substances perfluoromethyl butanone are assigned to the substance group of the fluoroketones, while cyclopentane is assigned to the substance group of the cycloalkanes.

According to the invention, a method for a heat pump system is proposed in which a Rankine heat pump process is made possible by a parallel connection of at least two evaporators, which enables efficient heat absorption from a plurality of different temperature controlled heat sources by means of a temperature track. This makes it possible to use a plurality of different heat sources, in particular a plurality of different waste heat sources, as efficiently as possible. The thermal energy withdrawn by the heat pump system from the heat sources may be at least partially provided for further use by the heat pump system.

Furthermore, a heat pump system according to the invention is proposed, which allows the execution or implementation of the method according to the invention. A power plant according to the invention comprises a heat pump system according to the invention. By means of the heat pump system, the thermal energy of a plurality of different waste heat sources of the power plant can be at least partially recovered and provided. As a result, the efficiency of the power plant, in particular a combined cycle power plant, improved.

Although the invention has been further illustrated and described in detail by the preferred embodiments, the invention is not limited by the disclosed examples, or other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102014213542 A1 [0007]

Claims (20)

Method for operating a heat pump system (1), in which a working fluid circulates within a directed working circuit (100) of the heat pump system (1), in which the working fluid is compressed by means of a compressor (20, ..., 25) and conveyed by means of a condenser (4 ) is liquefied, wherein a mass flow of the working fluid before the supply line to a first and second evaporator (31, 32) divided (102) and the first and second evaporator (31, 32) is supplied in parallel and in which the working fluid at a first Evaporating pressure (411) in the first evaporator (31) and at a second evaporation pressure (412) reduced in relation to the first evaporation pressure (411) is evaporated in the second evaporator (32), characterized in that the first evaporator (31) thermally with a first heat source (41) having a first heat source temperature and the second evaporator (32) thermally with a second heat source (42), one opposite the first Wärmequel lentemperatur lower second heat source temperature, is coupled. Method according to Claim 1 in which a respective waste heat of a power plant, in particular a gas-and-steam combined cycle power plant, is used as first and second heat source (41, 42). Method according to Claim 2 in which a waste heat of a flue gas is used as the first heat source (41) and waste heat from a transformer cooling is used as the second heat source (42). Method according to Claim 2 or 3 in which at least one of the heat sources (41, 42) waste heat of a flue gas, transformer cooling, transmission cooling, engine cooling, condenser cooling a housing of a heat recovery steam generator, a gas turbine acoustic hood, a generator cooling and / or a lubricating medium supply is used. Method according to one of the preceding claims, in which the working fluid is supplied in parallel to a first expansion valve (51) before being fed to the first evaporator (31) and to a second expansion valve (52) before being fed to the second evaporator (32). Method according to one of the preceding claims, in which a first and a second compressor (21, 22) are used for compression (120), wherein the working fluid discharged from the first evaporator (31) is from the first compressor (21) and from the second Evaporator (32) discharged working fluid to the second compressor (22) is supplied. Method according to Claim 6 in which a common motor shaft (10) is used for the first and second compressors (21, 22). Method according to one of Claims 1 to 5 in which a common compressor (20) is used for compression (120), wherein the working fluid discharged from the first and second evaporators (31, 32) is supplied to the common compressor (20). Method according to Claim 8 in which the working fluid discharged from the first evaporator (31) before the supply line to the common compressor (20) to a first check valve (61) and the second evaporator (32) discharged working fluid before the supply line to the common compressor (20) a second check valve (62) is passed. Method according to Claim 8 or 9 in which a multi-stage turbocompressor (20) is used as the common compressor (20), the working fluid discharged from the first evaporator (31) from a first compressor stage (201) of the turbocompressor (20) and that from the second evaporator (32) Working fluid of a second compressor stage (202) of the turbocompressor (20) is supplied. Method according to one of Claims 8 to 10 in which a regulation of a partial mass flow (71, 72) of the working fluid discharged from the first and / or second evaporator (31, 32) takes place before the supply to the common compressor (20). Method according to one of Claims 6 to 11 in which the working fluid discharged from the first and second or common compressors (21, 22, 20) is directed to the condenser (4). Heat pump system (1) comprising at least one compressor (20, ..., 25), a condenser (4) and at least one first and second evaporator (31, ..., 25), wherein the heat pump system (1) a directed Working cycle (100) for a circulating working fluid, wherein the working circuit (100) is adapted to divide a mass flow of the working fluid before a supply of the working fluid to the first and second evaporators (31, 32) (102) and parallel to the first and second evaporators ( 31, 32), wherein the first evaporator (31) has a first evaporation pressure (411) and the second evaporator (32) has a lower second evaporation pressure (412) than the first evaporation pressure (411), characterized in that the heat pump system (1 ) comprises at least a first and second heat source (41, 42), wherein the first heat source (41) has a first heat source temperature and the second heat source (42) one opposite the first Heat source temperature lower second Heat source temperature, and the first heat source (41) is thermally coupled to the first evaporator (31) and the second heat source (42) thermally coupled to the second evaporator (32). Heat pump system (1) according to Claim 13 , with a first and second compressor (21, 22), wherein the working circuit (100) of the heat pump system (1) is designed for the first evaporator (31) discharged working fluid to the first compressor (21) and from the second evaporator ( 32) discharged working fluid to the second compressor (22). Heat pump system (1) according to Claim 14 , characterized in that the first and second compressors (31, 32) have a common motor shaft (10). Heat pump system (1) according to Claim 13 , with a common compressor (20), wherein the working circuit (100) of the heat pump system (1) is adapted to direct the working fluid discharged from the first and second evaporators (31, 32) to the common compressor (20). Heat pump system (1) according to Claim 16 , characterized in that the common compressor (20) is designed as a multi-stage turbocompressor (20). Heat pump system (1) according to one of Claims 13 to 17 , with at least one expansion valve (51, ..., 55) and / or at least one mass flow controller (71, ..., 74). Power plant, in particular gas and steam combined cycle power plant, characterized in that this is a heat pump system (1) according to one of Claims 13 to 18 includes. Power plant according to Claim 19 , characterized in that the heat sources are designed as differently tempered waste heat sources of the power plant.

Images