Heat pump device for energy-efficiently generating process heat, drying device for drying an article to be dried, and method for operating a heat pump device - Patents.com

Abstract

The present invention relates to a heat pump apparatus for the energy-efficient production of process heat, comprising a circulating process fluid, an evaporator and at least one compressor, the heat pump apparatus comprising a first mixing separator at a second pressure stage, the first mixing separator having a first connection for the inflow of the vapour-form circulating process fluid, a second connection for the inflow of the condensed circulating process fluid and a third connection for the outflow of the vapour-form circulating process fluid, and a second compressor connected downstream of the mixing separator, whereby the outgoing vapour-form circulating process fluid is converted in the second compressor from the second pressure stage to the first pressure stage. The present invention relates to a heat pump device, in which a circulating process fluid that is compressible and condensed in a heat sink for transferring process heat to at least one associated heat exchanger can be directed back into a first mixing separator of a second pressure stage, while the circulating process fluid in vapor form can be introduced into a first compressor mixing separator, the at least one first mixing separator having the fourth connection for the outlet of the condensed circulating process fluid, whereby the condensed circulating process fluid that leaves can be directed back into an evaporator and / or fed into at least one second compressor.Furthermore, the present invention relates to a drying device and a method for operating a heat pump device.

Description

[Technical Field]

[0001] The present invention relates to a heat pump apparatus for energy-efficient generation of process heat, the heat pump apparatus having a heat absorption side, a heat release side, a circulating process fluid, and an evaporator on the heat absorption side, the heat pump apparatus being capable of corresponding a heat exchanger and at least one heat sink on the heat release side and at least one heat source on the heat absorption side, the evaporator being capable of indirectly heating the circulating liquid process fluid with heat supplied from the corresponding heat source and evaporating it at a pressure stage of the evaporator, the heat pump apparatus having at least one first compressor connected downstream of the evaporator, the at least first compressor being capable of compressing the circulating vapor process fluid from the pressure stage of the evaporator to a second pressure stage. Furthermore, the present invention relates to a drying apparatus for drying an article to be dried with a heated process gas stream, and a method for operating a heat pump apparatus.

[0002] In the course of the energy transition and due to the current crisis in natural gas supplies, heat pump processes have become the focus of process heat generation. While heat rejection for heating living spaces occurs at low temperature levels, industrial heating processes often require significantly higher temperatures. For example, industrial drying processes require large heat inputs, some of which can be several MW, at high temperatures well above 100 °C, often exceeding 200 °C, and as a whole are the largest emitters of greenhouse gases in the industrial sector. These high temperatures are conventionally generated by combustion processes of fuels, usually carbon-based, solid, liquid, or gaseous.

[0003] Producing process heat by combustion processes or electrically operated heaters, for example, requires a primary energy use approximately equal to the process heat output to be produced. In other words, for industrial decarbonization, primary energy use for process heat generation can and should be significantly reduced by replacing, to a large extent, the combustion processes previously required to achieve temperatures above 120°C to 200°C with suitable, highly efficient, electrically driven, high-temperature heat pumps.

[0004] In general, a heat pump process for generating process heat is determined by the driving power, the required temperature on the heat absorption side, the achievable temperature on the heat release side, and the resulting coefficient of performance (COP) as the quotient of the heat output with respect to the temperature lift between heat absorption and heat release. h The heat pump can be characterized by the following: Up to now, attempts to develop economical high-temperature heat pumps with heat release above, for example, 200°C have failed because the temperature lift is too small. This is because, based on the thermodynamic relationships in cyclic processes, an increase in the temperature lift results in a decrease in the heating coefficient of performance. Therefore, the operation of previously known cyclic processes requires high heat source temperatures on the heat absorption side, which are themselves expensive heat sources with correspondingly uneconomically high costs or which have to be manufactured rather than being available as waste heat sources.

[0005] The value of process heat is usually rated according to the magnitude of its temperature level. In a heat pump circulation process, the temperature level of the released process heat is typically obtained by compressing the circulating process fluid. The specific driving work for compression corresponds to the specific exergy consumption, i.e., the specific exergy dissipation. The magnitude of the specific exergy dissipation is also related to the minimum applied compression pressure that must be overcome in order for the circulating process fluid to reach the required temperature and be able to transfer the process heat under the maximum sink temperature.

[0006] That is, the higher the highest required sink temperature for transferring process heat, the more specific exergy is dissipated and the more valuable the process heat produced, i.e., the specific exergy dissipation required to produce lower value process heat is less than the specific exergy dissipation required for higher value process heat.

[0007] Heat pump processes are generally divided into circulatory processes in which no phase change of the circulating process gas takes place, and circulatory processes in which the circulating process fluid undergoes a phase change from liquid to gas in an evaporator on the heat absorption side, in which the gas-to-liquid phase change takes place by condensation in a condenser or by transcritical cooling in a gas cooler.

[0008] Known high-temperature heat pumps, which do not always involve a gas cycle and a phase transition of the process gas, such as the rotary heat pump from the Austrian company ecop Technologies GmbH (AT-4531 Neuhofen an der Krems) (www.ecop.at), are based on the left-handed Joule process and can indeed heat sink temperatures of at least 150°C with a relatively high coefficient of performance of about 4. However, they can only achieve a very low temperature lift of about 55 K, and the maximum heat output of each heat pump is limited due to their design. In principle, it is possible to arrange such heat pumps in multiple stages to overcome a higher overall temperature lift, but this leads to a significantly lower coefficient of performance due to the extremely high drive power required for the same heat output, which in turn leads to low economic efficiency and a limit to the absorbed and dissipated heat output due to the design.

[0009] In heat pump circulation processes where a phase change of the circulating process fluid occurs by evaporation, a distinction is made between heat pumps where the circulating process fluid is condensed on the heat rejection side, and transcritical operation heat pumps where the circulating process fluid is rejected in a gas cooler under supercritical pressure, with carbon dioxide (CO2) as the circulating process fluid. The essential difference between both types of circulation processes where a phase change of the circulating process fluid occurs is that transcritical operation heat pumps deliver heat power over an extended temperature range and not at a fixed temperature plateau, as in the case of condensation operation.

[0010] Transcritical CO2 heat pumps have already been constructed recently, for example as described in EP 2 321 589, up to a sink temperature of approximately 120°C. In transcritical heat pumps, the condensation pressure is not reached, since no actual condensation takes place in the condenser. However, for the heat transfer in the gas cooler from the supercritical circulating process fluid to the heat sink to be supplied at high temperature, a correspondingly high compression pressure above the critical point of the circulating process fluid must be achieved by applying mechanical work to compress the heat-rejecting fluid to the corresponding supercritical pressure.

[0011] The advantage of a transcritically operated heat pump with a supercritically operated gas cooler is that the circulating process fluid can only be cooled in the gas cooler to a temperature at most above the inlet temperature of the heat sink and still retains part of its specific heat, which may be sufficient for the process heat supply of a lower value heat sink. This does require mechanical work to exceed the highest sink temperature, but no additional mechanical compression is required for the subsequent supply of a lower value heat sink.

[0012] However, at the same time, this advantage of transcritical operation heat pumps is accompanied by a major drawback. Continuous cooling of the supercritical circulating process fluid by heat transfer in the gas cooler presupposes that each heat sink still transfers sufficient process heat despite this continuous temperature loss of the circulating process fluid. For this to occur, the inlet and outlet temperatures of each heat sink must be sufficiently low. If this is not the case, i.e., if the lowest sink temperature is still too high to cool the supercritical circulating process fluid sufficiently below its critical point, the transcritical process becomes uneconomical or even impossible, since in this case the evaporator on the endothermic low-pressure side of the transcritical circulating process often cannot operate correctly.

[0013] A further major drawback of transcritically operating heat pumps with CO2 as refrigerant, aimed at being able to supply process heat to sink temperatures well above 120°C, is the combination of high compression pressures, in this case well above 120 bar, with high CO2 outlet temperatures, well above 130°C, which necessarily means that the construction of oil-lubricated piston or screw compressors presents previously unresolved technical problems in terms of material strength and the heat resistance of the oil. The mere fact that the compressors must be oil-lubricated, since frictional forces at high pressures are too high for oil-free compression, necessitates effective oil management so that subsequent units, such as gas coolers and evaporators, are not impaired in their effectiveness by oil components contained in the circulating process fluid.

[0014] A further disadvantage of known heat pumps with refrigerants such as CO2, NH3 and hydrocarbons is their limitation in heating on the heat absorption side of the heat source significantly above 30-40° C. Even if such a heat source were technically possible, the technically achievable temperature lift in each case would be very small, and on the heat release side, high temperatures for the transfer of process heat to the heat sink above 200° C would not be attainable.

[0015] In a heat pump circulation process involving condensation of a circulating process fluid, the condensation temperature to be generated for heat transfer must be sufficiently higher than the temperature of the heat sink to be supplied, which has the highest sink temperature. That is, the highest required sink temperature and the selection of the circulating process fluid for its condensation temperature, which depends on the pressure, determine the pressure required in the condenser, i.e., the heat exchanger of the heat sink where the heat dissipation of the heat pump circulation process takes place. In this case, the condensation pressure must usually be achieved by compression of the circulating process fluid by mechanical work, i.e., by dissipation of exergy.

[0016] The current development of novel heat pumps with condensing circulating process fluids has long focused on the search for suitable circulating process fluids to achieve the highest possible condensation temperature at the lowest possible condensation pressure on the heat release side, while simultaneously achieving the highest possible evaporation pressure at the lowest possible evaporation temperature on the heat absorption side.

[0017] However, many of the fluids suitable as circulating process fluids, also called refrigerants, that come as close as possible to these properties usually have very poor environmental compatibility with respect to air pollution, ozone depletion, flammability, or toxicity. Therefore, natural refrigerants such as CO2, NH3, and less harmful but flammable hydrocarbons are increasingly being used. However, it is still recognized that almost all refrigerants that are still actually approved by the EU Commission have large or very large limitations regarding the height of the maximum sink temperature and the temperature lift that can be achieved.

[0018] This includes, for example, industrial heat pumps using the natural refrigerant NH3, which usually operate with condensation of the circulating process fluid and which in the past were already referred to as high-temperature heat pumps when the maximum possible sink temperature was, for example, 80-90°C. This is due to the critical point of NH3 at 132.35°C and 113.53 bar, whereby a temperature of 80-90°C can already be considered to be just below the critical point. That is, NH3 is already supercritical at a temperature of 200°C and cannot be further condensed, and can only be further used in transcritical processes under very high pressure.

[0019] Due to the relatively low critical point of NH3, for example, pressures exceeding 62.55 bar can be overcome for condensation of NH3 at 100°C. Such high pressure levels require high specific compressor work, increasing the operating costs for compression. This in turn makes the oil-lubricated compressor and heat exchanger structures complex and expensive. Furthermore, the specific condensation enthalpy of NH3 is only 715.7 kJ / kg at 100°C, resulting in an uneconomically low heat coefficient of performance. For many industrial processes, a temperature level of 100°C is also insufficient.

[0020] For CO2, the critical point is even lower, i.e., 31.06°C and 73.83 bar, so above 31.06°C CO2 is already outside the two-phase region and cannot be further condensed, and can only be further utilized for heat transfer in transcritical processes above the critical pressure. Due to the high pressure consumed, the same strict limitations as for NH3 apply in terms of design and operation.

[0021] The above-mentioned circulating process fluids exist in gaseous form under standard conditions. Due to their high vapor pressures, e.g., at 0°C (34.85 bar for CO2 and 4.29 bar for NH3), they are extremely well suited for generating process cooling, highlighting their excellent suitability as refrigerants. An advantage of both fluids is their relatively low specific volume: e.g., at an evaporation temperature of 54°C, the specific volume is 57 L / kg for NH3 and 5.6 L / kg for CO2. This allows for relatively small equipment sizes even with high evaporation outputs. In the supercritical range, the specific volume of both fluids is even less than 10-20 L / kg, which is extremely advantageous for the structural size of the heat exchanger. However, even in this case, high supercritical pressures are used, which complicates the equipment design.

[0022] The use of water vapor as a circulating process fluid is already known, especially in power generation technology, for clockwise power processes to generate electricity, whereas electrically driven heat pumps with water vapor as a circulating process fluid for counterclockwise work processes have not been so called until now. However, when so-called water heat pumps are currently mentioned, they usually mean heat pumps in which a water stream is heated at least on the heat release side and possibly also cooled on the heat absorption side, but in which the circulating process fluid is not water but another fluid.

[0023] Compressing water vapor by vapor compression, often used to increase the condensation temperature of water vapor so that it is available for heat transfer at a slightly higher temperature level, as in modern evaporation processes using mechanical vapor compression, is widely known as a type of heat pump, but is not usually constructed in the form of a traditional circulation process. In this case, extremely high calculated heat performance coefficients, sometimes well above 20, are achieved with a low temperature lift of a few Kelvin. However, this is a misleading assessment, since this is not the typical counterclockwise circulation process for heat pumps, which is materially closed. In any case, for higher temperature lifts above 10-20 Kelvin, a multi-stage structure is usually required, which significantly reduces the overall achievable heat performance coefficient.

[0024] Compressors for water vapor are configured in various forms, for example as fluid machines in the form of radial fans for high volume flows at low compression ratios of less than 2 and low end pressures of less than 5 bar, or as turbocompressors for medium compression ratios of up to about 3 and high end pressures of up to about 20 bar, and as displacement machines in the form of rotary piston compressors for high volume flows at medium compression ratios or piston machines for high compression ratios of up to 6 and particularly high end pressures of more than 70 bar.

[0025] For example, the company Spilling Technologies GmbH (Hamburg) (www.spilling.de) describes such piston steam compressors for high outlet pressures of up to 70 bar, which, due to their design, are generally unable to aspirate vacuum steam below 100°C, but can only aspirate steam at significantly higher pressures than atmospheric pressure. Nowadays, these piston steam compressors are limited to steam temperatures of approximately 250°C up to a pressure stage of approximately 40 bar in a given design and are even manufactured without oil lubrication of the pistons. To achieve this, and in order to reduce superheat in the compressor, a defined amount of water is injected into the aspirated steam flow before it enters the cylinder, so that the steam fraction x is reduced before compression. D and simultaneously the liquid ratio (1-x D ) is produced, the liquid fraction of which provides sufficient lubrication for the piston during compression and evaporates due to the temperature increase during polytropic compression, resulting in saturated vapor at the compressor outlet, ideally not significantly superheated.

[0026] The company Piller Blowers & Compressors GmbH (Möhringen, Germany) (www.piller.de) describes a steam compressor in the form of a fan, which is used for steam compression in the vacuum region and is actually built up to an outlet pressure of 5 bar overpressure. To achieve a high temperature lift, it is connected in series in multiple stages. Due to the temperature-dependent material strength of the compressor rotor, at the high peripheral speeds required for compression, the aspirated steam flow is injected with a certain amount of cooling water before entering the compressor rotor.

[0027] Similarly, the company Boldrocchi Group Srl (Biassono, Italy) (www.boldrocchigroup.com) describes steam fans and turbocompressors in the form of ventilators for compression ratios of about 1.2 to 3.0 and end pressures up to 100 bar, and various compressor stages to reach higher temperature lift. Boldrocchi Group also describes over-saturating the steam with injected water before it enters the compressor rotor to reduce superheat in the compressor.

[0028] The advantage of wet vapor compression is the continuous cooling during compression due to the evaporating liquid fraction. Similarly, the compression is carried out at an overall lower temperature than in the case of dry superheated vapor due to the compensated superheat, so that the specific volume during wet vapor compression is smaller than in the case of uncooled compression of dry vapor in the superheated region, which reduces the construction size of the compressor for the same mass flow rate.

[0029] However, the drawback of wet steam compression is that the vapor fraction x D In addition to the mass flow rate of the liquid water that evaporates during compression and is injected before compression (1-x D ) must also be accelerated to high peripheral speeds in the compressor rotor and compressed to the outlet pressure. Furthermore, this water fraction of the wet steam inside the compressor rotor, which evaporates to saturated steam, increases its specific volume by three orders of magnitude and is correspondingly accelerated by the increased volumetric flow rate, which leads to a higher specific drive torque with respect to the mass flow rate.

[0030] A further drawback is that the water fraction of the wet steam enters the compressor rotor as a liquid and impinges on the rotor structure as a liquid, which results in stronger mechanical loading of the surface and increases fluid friction within the compressor rotor.

[0031] Furthermore, the injected water must be treated, or at least descaled, to avoid lime deposits in the compressor.

[0032] In particular in a staged compression arrangement to provide a saturated steam mass flow at the outlet of the final compression stage, each compression stage must compress the saturated steam mass flow leaving the preceding stage and additionally the mass flow of water injected into each stage, which is required for desuperheating.

[0033] The interaction of these drawbacks results in an overall increase in the specific driving power of the compression relative to the saturated steam mass flow supplied.

[0034] A further significant drawback of known vapor compression or steam compressors for providing high-value steam by utilizing low-temperature waste heat at 60-80° C., for example in the form of vacuum steam, is that when the condensed steam transfers its heat of condensation to a heat sink at a high sink temperature, i.e., the liquid vapor condensate still has a significantly higher temperature, which can lead to a new evaporation in a materially closed circulation process from the same low-temperature waste heat source at 60-80° C. Therefore, in known vapor compression, besides the implementation of a materially closed circulation process, which can be called a heat pump circulation process, the required cooling of the condensed circulation process fluid to the temperature of the heat-absorbing low-pressure steam is not performed.

[0035] Furthermore, industrial processes often include multiple heat sinks to which process heat must be supplied, often at different temperature levels. In order to supply a variety of such heat sinks with a common heat pump process during condensing operation, the design must likewise be tailored to supply the most valuable heat sink with the highest required sink temperature.

[0036] A typical example for industrial processes with high process heat demands, in part from several megawatts to high temperatures exceeding 200°C, is a large-scale technical drying process, such as a spray drying process for producing powders. In such spray drying processes, the high flow rate of the consumed process gas, enriched with water vapor, usually generates a large waste heat output, similar in scale to the heat demand for heating the drying process. However, this waste heat is consistently generated at low process temperatures, e.g., 60-80°C.

[0037] If heating with process heat is to be carried out at high sink temperatures, e.g. above 200°C, conventional heat pumps can only achieve a high heating coefficient of performance if a corresponding amount of heat is supplied on the low temperature side to the heat pump circulation process and the technically achievable temperature lift is not lower than the difference between the highest required sink temperature and the lowest available temperature level of the low temperature heat source.

[0038] To upgrade low-temperature waste heat streams from the 60-80°C temperature levels frequently encountered in industry with heat pump technology having an economically useful heat coefficient of performance clearly above 2, ideally above e.g. 3-5, so that they can be utilized as high-value process heat at consistently high temperature levels above 200°C, a temperature lift of at least 120-140 Kelvin would be required. Heat pump technology enabling such a heat pump circulation process has not been available to date.

[0039] German Patent Application No. DE 10 2013 008 080 A1 discloses an apparatus for refrigeration and heat connection, which comprises a refrigeration circuit and a heat pump circuit as two left-handed refrigerant vapor processes thermally connected to one another via a common intermediate-pressure tank, the refrigeration circuit having an evaporator for evaporating a refrigerant and thus generating a refrigeration output, a refrigeration compressor and a throttle valve, and the heat pump circuit having a heat pump compressor for increasing the pressure of the refrigerant vapor, a condenser for liquefying the refrigerant and a heat pump throttle valve for reducing the pressure of the refrigerant to an intermediate pressure level.

[0040] US Patent Application Publication No. 2012 / 0116594 discloses a pump system for thermal management in which a supersonic ejector is used instead of a conventional compressor. In this system, the flow coming from the evaporator is mixed with a part of the flow from the compressor in the ejector and introduced into a separator. The other flow downstream of the compressor is condensed in a condenser and expanded to the intermediate conditions of the separator by an expansion valve. The liquid phase of the separator passes through the expansion valve and expands to the conditions of the evaporator, and at the outlet of the evaporator, vapor is drawn from the ejector.

[0041] EP 2317251 A1 describes a two-stage compression heat pump cycle using NH3 as a heat transfer medium. A condenser is arranged downstream of the oil separator, followed by a first cooling device connected to an intercooler. The liquid phase from the intercooler is guided to the second cooling device and an evaporator, and then returned to the intercooler via a lower-stage compressor. The vapor phase from the intercooler enters a higher-stage compressor connected to the oil separator to separate the oil contained in the gaseous heat transfer medium from the lubricating oil used for the higher-stage compressor. The separated lubricating oil is returned to the gas inlet side of the higher-stage compressor or the lower-stage compressor via a return line.

[0042] Chinese Patent Application Publication No. 113251698 relates to a multi-stage compression heat pump system for recovering waste heat in a power plant, which includes a high-pressure compressor, an intermediate-pressure compressor, and a low-pressure compressor. In the low-pressure stage, an evaporator and a gas-liquid separator are arranged upstream of the low-pressure compressor, which delivers heat to a first intermediate cooler. The outlet of the first intermediate cooler is connected to the intermediate-pressure compressor, which also delivers heat to a second intermediate cooler. From the second intermediate cooler, the outlet passes through the high-pressure compressor into a condenser, and then, via the condenser outlet and an intermediate liquid reservoir, is gradually guided back to each individual pressure stage via a throttle valve.

[0043] The object of the present invention is to improve upon the prior art.

[0044] The object is to provide a heat pump device for energy-efficiently generating process heat, the heat pump device having a heat absorption side, a heat release side, a circulating process fluid, and an evaporator on the heat absorption side, the heat pump device being capable of being associated with at least one heat exchanger and at least one heat sink on the heat release side, and at least one heat source on the heat absorption side, the evaporator being capable of indirectly heating the circulating liquid process fluid with the heat supply from the associated heat source, and evaporating the circulating liquid process fluid at a pressure stage of the evaporator, the heat pump device has at least one first compressor connected downstream of the evaporator, by means of which the vaporous circulating process fluid can be compressed from the evaporator pressure stage to a second pressure stage, and the heat pump device has at least one first mixing separator at the second pressure stage, the at least first mixing separator having a first connection for the inflow of the vaporous circulating process fluid, a second connection for the inflow of the condensed circulating process fluid, a third connection for the outflow of the vaporous circulating process fluid, and a third connection for the outflow of the condensed circulating process fluid. and an optional fourth connection for the outlet of the circulating process fluid of the first pressure stage, downstream of the mixing separator is connected at least one second compressor, whereby the circulating process fluid in vapor form leaving the third connection can be compressed in the at least second compressor from the second pressure stage to the first pressure stage, and by means of at least one associated heat exchanger, process heat can be transferred indirectly from the circulating process fluid in vapor form of the first pressure stage to at least one associated heat sink, and the circulating process fluid condensed in the at least one heat exchanger is and via the second connection, the circulating process fluid in vapor form can be introduced into the mixing separator from the at least first compressor via the first connection, and the at least first mixing separator has a fourth connection for the outlet of the condensed circulating process fluid, whereby the condensed circulating process fluid that flows out can be directly or indirectly led back into the evaporator and / or fed into the at least second compressor.

[0045] Therefore, when at least one mixing separator in the second pressure stage is arranged, a high-temperature heat pump is provided that is capable of dissipating process heat in the temperature range of approximately 100°C to 250°C on the heat dissipation side by at least one heat exchanger in the first pressure stage.

[0046] For this purpose, the fourth connection of at least the first mixing separator can be connected directly or indirectly by at least one line to the evaporator and / or to at least the second compressor.

[0047] Particularly advantageously, the heat pump device can be operated with natural or completely environmentally compatible circulating process fluid, particularly preferably water.

[0048] Water is liquid under standard conditions and has the advantage of a high critical pressure of 221.2 bar and a high critical temperature of 374.15°C, which means that in the two-phase region, already at relatively low pressures of e.g. 16 bar and condensation temperatures above 201°C, a high condensation enthalpy of 1,933 kJ / kg is available for heat transfer to the heat sink, whereas in comparison the specific condensation enthalpy of NH3 is only 715.7 kJ / kg at only 100°C and already at 62.55 bar.

[0049] Therefore, there is provided a heat pump device comprising a heat pump circulation process based on a circulation process comprising at least three pressure stages of different pressure levels, said heat pump device comprising: at least one first pressure stage having a pressure of the vaporous circulating process fluid, the first pressure stage corresponding to the maximum condensation pressure of the circulating process fluid on the heat rejection side of the circulating process, whereby the condensation temperature of the circulating process fluid is above the highest required sink temperature of the high-value heat sink to be supplied, such that the condensation temperature of the circulating process fluid is sufficient to transfer heat from the condensed circulating process fluid to the high-value heat sink; at least one second pressure stage having a pressure of the circulating process fluid in vapor form lower than the pressure of the first pressure stage and higher than the vapor pressure of the circulating process fluid in the evaporator, in which at least one mixing separator is arranged; at least one lowest pressure stage having a pressure of the circulating process fluid in vapor form corresponding to the evaporation pressure in the evaporator, which corresponds to the lowest condensation pressure of the circulating process fluid in the circulating process of the heat pump device; Includes.

[0050] The essential idea of ​​the present invention is to reduce the dissipation of specific exergy in the specific compressor work that must be consumed as a whole relative to the specific process heat available at the pressure level with the highest required sink temperature. This is achieved by making the condensation enthalpy of the condensed circulating process fluid available as process heat at the condensation pressure of a first pressure stage for the heat sink with the highest required sink temperature, and by successive enthalpy utilization of the condensed circulating process fluid after the enthalpy contained in the condensed circulating process fluid of this first pressure stage is partially supplied to the vaporous circulating process fluid of at least one second pressure stage in at least one mixing separator in the compression path. When the condensed circulating process fluid of the first pressure stage, having approximately the condensation temperature, passes into at least one mixing separator of the second pressure stage, i.e., a lower pressure stage with a lower condensation temperature, the liquid circulating process fluid is cooled to the condensation temperature of the lower pressure stage, and part of its enthalpy is utilized for the evaporation of part of the liquid circulating process fluid. This evaporated fraction is fed to the already vaporous flow rate of the circulating process fluid in the compression path of this lower pressure stage without compressor work, thereby increasing the condensation enthalpy of the vaporous circulating process fluid available at this pressure stage, while the compressor work consumed up to this pressure stage remains constant, thereby increasing the heat coefficient of performance and improving energy efficiency.

[0051] The following terms are explained: A "heat pump device" is a machine that absorbs thermal energy from a reservoir and / or a lower temperature heat source, in particular while consuming technical work, and transfers it together with the driving energy as useful heat to a system to be heated and / or a heat sink having a higher temperature. A heat pump device is particularly configured to perform a heat pump circulation process in a circulating process fluid with the aim of absorbing heat from an available heat source of a lower temperature and transferring the absorbed heat to at least one highest sink temperature required for the heat sink by increasing its temperature through mechanical work.

[0052] A "heat pump circulation process" is in particular a circulation process in which a closed quantity of substance of a circulation process fluid is evaporated by heat supply, in particular from the reservoir side and / or from the low-pressure heat source side, and then the vaporous circulation process fluid is compressed to a high pressure, in particular by performing mechanical work, or by another process, for example by mixing with a vaporous circulation process fluid at a higher pressure in a mixing separator, or a combination thereof, in which it receives a higher temperature, and then at least cooled or condensed at this high pressure by heat removal on the side of the heat sink, and then brought again to a low pressure before evaporation by at least throttling or heat removal.

[0053] A "circulating process fluid" is a fluid that, under certain physical conditions, exists in liquid, gaseous, or both states simultaneously. When both states exist simultaneously, it is referred to as a two-phase state, and its representation in a phase diagram is within the two-phase region between the boiling and condensation lines. Alternatively, it is a fluid that exists supercritically. Such fluid states are depicted outside the two-phase region, i.e., at pressures above the fluid's critical pressure or temperatures above the fluid's critical temperature. Furthermore, a given amount of liquid or vapor circulating process fluid at any pressure stage can be withdrawn from the circulating process per unit of time for other thermal or material uses. At the same time, the same amount of liquid or vapor circulating process fluid can be supplied to the circulating process at another location per unit of time. This can be, for example, a vapor circulating process fluid used as a heating medium or driving steam for an external process and then supplied to the circulating process in liquid form elsewhere, e.g., as condensed circulating process fluid. Likewise, withdrawal points are possible for withdrawing circulating process fluid, in particular sporadically or continuously, for cleaning purposes, and the cleaned circulating process fluid can be introduced back into the circulating process at another supply point, in order to control and / or regulate the quality of the circulating process fluid inside the heat pump device and its filling level.

[0054] "Process heat" is specifically heat that is rejected to a heat sink using at least one heat exchanger in a first pressure stage or to another heat sink using another heat exchanger in another pressure stage.

[0055] A "heat sink" is, in particular, a reservoir and / or flow section with an inlet and an outlet for a fluid or heat transport medium, the temperature of which must be increased from the inlet temperature at the inlet to the outlet temperature at the outlet, where the target temperature to be achieved for the outlet temperature of the heat sink is the "highest required sink temperature" of the heat sink. The heat sink may also be a heat transport medium that is heated to heat another fluid and / or substance flow, in particular in an external device outside the heat pump device, for example, in a heat exchanger, whereby a heat transport medium is heated, which is then used to heat an external process, its auxiliary medium, or its drying product in another device, for example, a dryer. The heat sink may also be a process gas stream that is heated to dry the wet material in a drying device, whereby the heated process gas transfers heat to the wet material and thus to the drying product, evaporating the moisture contained therein and possibly removing it from the drying product, thereby driving the drying process.

[0056] A "heat source" is, in particular, a reservoir whose heat can be utilized to transfer heat and / or waste heat to a circulating process fluid. The heat source may be a flow section with an inlet and an outlet of a fluid or heat transfer medium, and the temperature of the heat source may be reduced from the highest available temperature, i.e., the lowest available heat source temperature, from the inlet temperature of the inlet to the outlet temperature of the outlet, in which case, in particular, the target temperature for heat transfer in the evaporator is the "lowest possible heat source temperature" of the outlet of the heat source. The heat source may also be a waste heat stream utilized to heat the evaporator of a heat pump device to supply sufficient heat to the circulating process in a lower pressure stage of the circulating process fluid so that sufficient process heat can be provided to at least one heat exchanger. The heat source can also be the process gas stream exiting the dryer after drying the wet material, i.e., waste heat and the heat content of the process gas stream are utilized for heat recovery via the heat source heat exchanger to heat the evaporator of the heat pump device. In this case, the dryer often has high heat loss via the process gas stream, and this process gas stream exiting the dryer after drying the wet material generally reaches the required process heat content of the dryer, but is usually available at a significantly lower temperature level and can therefore be used to heat the evaporator of the heat pump device. The heat source can also be the heat release side of a cooling device used to generate process cooling, e.g., waste heat, whose released heat is used to heat the evaporator of the heat pump device. The heat source can also be the heat release side of a cooling device or heat pump used to generate process cooling, whose released heat is used in the heat source heat exchanger to indirectly heat the evaporator of the heat pump device. In cooling systems that often operate intermittently and are therefore subject to fluctuations in heat release, it is possible to additionally provide as constant a heat supply as possible for heating the evaporator of the heat pump system, particularly for compensation purposes. Such compensation can be achieved in particular in the form of a combination of waste heat from various waste heat streams, for example from the process gas stream, with waste heat from the cooling system or heat pump, or with other waste heat.

[0057] "Waste heat" means a heat source, particularly when the heat is available at such a low temperature level that the heat sink with the highest required sink temperature located below, particularly in the vicinity of the heat source, does not exist or cannot utilize the heat as process heat, or the heat can no longer be utilized as process heat at an economically reasonable cost.

[0058] Abbreviation: COP h The "coefficient of performance-heat" is the quotient of the available process heat per unit time to the amount of mechanical work consumed per unit time, and is a characteristic value that indicates the energy efficiency of generating process heat, especially for heat pump devices.

[0059] A "heat exchanger" is, in particular, a device in which thermal energy, i.e., heat, is transferred from one relatively hot material stream to another relatively cold material stream, the two streams being spatially and materially separated from one another by a heat exchanger wall. Preferably, the heat exchanger is an indirect heat exchanger. The material stream flowing through the heat exchanger may be, for example, a circulating process fluid or the inflow or outflow of a heat sink or heat source fluid or heat transport medium. A heat pump device may have two or more heat exchangers on the heat absorption side and / or the heat release side.

[0060] An "evaporator" is a device or apparatus in which a liquid circulating process fluid changes its state form from liquid to gaseous, especially at a heat source side by indirect heat transfer, thereby causing a "phase transition" from liquid to gaseous, in which case the gaseous state of the circulating process fluid is generally called "vapor" if it is a circulating process in which at least one phase transition occurs between two states, whereas one gaseous state clearly indicates no phase transition. Evaporators are particularly located at the lowest and / or bottom-most pressure stage of a circulating process.

[0061] A "compressor" (also called a compressor) is a device or apparatus for compressing and / or increasing the pressure of a compressible fluid, such as a vapor-phase circulating process fluid, in particular with the purpose of reaching a higher pressure stage in order to increase the condensation temperature of the vapor-phase circulating process fluid. This is also called "upgrading" the heat content of the vapor-phase circulating process fluid for use as "high-value" process heat. Compressors are particularly designed as fluid machines, such as axial fans, radial fans, turbocompressors, or turbines. Compressors can also be designed as displacement machines, such as piston compressors, rotary piston compressors, or screw compressors. The compressor may be a thermal compressor, for example a vacuum vapor injection pump, in which a vaporous circulating process fluid of the second or first pressure stage is used as a motive vapor, and this motive vapor reaches a high velocity in the thermal compressor, thereby drawing in suction vapor in the form of a vaporous circulating process fluid of a lower pressure than the motive vapor, in which case the motive vapor and suction vapor are then mixed to form a mixed vapor having a pressure higher than the suction vapor and a pressure of a pressure stage having a lower pressure than the motive vapor.

[0062] A "compression path" is a series of compression steps of a vaporous circulating process fluid in at least two compressors connected directly or indirectly in series, regardless of the type of construction, for the purpose of compressing the vaporous circulating process fluid from at least one lower pressure stage to at least one higher pressure stage.

[0063] "Superheat" is specifically a state of the vaporous circulating process fluid where the temperature of the vaporous circulating process fluid exceeds the condensation temperature, which is a function of the prevailing pressure and / or pressure stage and is generally simplified as a temperature difference expressed in Kelvin. By contrast, the degree of superheat is properly understood to be the difference in specific enthalpy of the vaporous circulating process fluid from the specific saturated vapor enthalpy at the prevailing pressure, expressed in kJ / kg.

[0064] "Pressure stage" may be understood as a synonym for the total pressure reached at the outlet of the compressor, regardless of the configuration, in particular after compressing the vaporous circulating process fluid, and in particular to clarify in a heat pump device the stepwise compression of the vaporous circulating process fluid, with the corresponding boiling points and condensation temperatures of the circulating process fluid at the pressures of these pressure stages.

[0065] By "first pressure stage" is understood the pressure stage with the highest condensation pressure of the circulating process fluid in the heat pump device required to be able to supply process heat to the heat sink with the highest required sink temperature, for example in the pressure range from about 1 bar for process heat of about 100°C to about 40 bar for process heat of about 250°C.

[0066] "Evaporator pressure stage" may be understood as a pressure stage at which the evaporator of the heat pump device operates to evaporate a liquid circulating process fluid while supplying heat from a heat source, in particular in a pressure range between, for example, about 40 hPa at the lowest heat source temperature of about 30°C and about 1.4 bar at the lowest heat source temperature of about 110°C.

[0067] A "second pressure stage" may in particular be understood as a pressure stage that is lower than the first pressure stage and higher than or equal to the pressure stage of the evaporator, in which in particular at least one mixing separator is arranged.

[0068] A "third pressure stage" may in particular be understood as a pressure stage that is below the second pressure stage and above the evaporator pressure stage. A "fourth pressure stage" may in particular be understood as a pressure stage that is below the third pressure stage and above the evaporator pressure stage. A "fifth, sixth, seventh and optionally further pressure stages" may in particular be understood in the same way. The names of the pressure stages are used in particular to distinguish the respective current pressures and do not represent a definite order.

[0069] A "mixing separator" is a device that is assigned to a particular pressure stage, in particular having a pressure above the pressure stage of the evaporator and / or lower and / or equal to the first pressure stage, and that includes a volume and has at least one connection for the inflow of the vaporous circulating process fluid of the assigned pressure stage, a connection for the inflow of the liquid circulating process fluid of the assigned pressure stage, and a connection for the outflow of the vaporous circulating process fluid. The essential function of the mixing separator is in particular to saturate the flow rate of the superheated vaporous circulating process fluid after compression by mixing with the liquid circulating process fluid. Another function of the mixing separator may also be to depressurize and spontaneously evaporate the liquid circulating process fluid, for example from a higher pressure stage, when the temperature of the liquid circulating process fluid is higher than the associated condensation temperature of the assigned pressure stage of the mixing separator.

[0070] According to the invention, at least the first mixing separator has a fourth connection for the outlet of the condensed circulating process fluid, so that the condensed circulating process fluid that leaves can be led directly or indirectly back into the evaporator and / or fed into at least the second compressor.

[0071] Thereby, at least the first mixing separator may have an outlet connection for the liquid circulating process fluid of the pressure stage assigned to the mixing separator, through which connection exits excess liquid circulating process fluid that is not required or consumed for saturation by the inlet connection for the vaporous circulating process fluid that, if possible, is superheated and flows into the mixing separator, or that does not evaporate by spontaneous evaporation when flowing into the mixing separator, and that leaves the mixing separator at the corresponding condensation temperature of the assigned pressure stage of the mixing separator.

[0072] The liquid circulating process fluid leaving at least the first mixing separator is guided back to the evaporator via a condensate separator. A partial flow of the liquid circulating process fluid can also be fed to the second compressor via a condensate pump and / or a regulating valve. This allows the liquid circulating process fluid leaving at least the first mixing separator to be used to generate wet steam.

[0073] To provide an interface to at least one heat sink, the heat pump device has at least one heat exchanger assigned to the first pressure stage and / or a heat exchanger assigned to the second pressure stage and / or a heat exchanger assigned to a pressure stage below the second pressure stage on the heat dissipation side.

[0074] In another embodiment, the heat pump device may have at least one heat source and / or at least one heat sink.

[0075] To provide an adaptable multi-stage, modular structure and to achieve the division of compression, the heat pump device has a second mixing separator, a third mixing separator, a fourth mixing separator, and / or optionally further mixing separators, each of which is connected upstream of a respective further compressor.

[0076] Thus, two or more mixing separators may be arranged between the evaporator and the first pressure stage, in particular connected in series.

[0077] By using a multi-stage structure and dividing the compression of the vapor-phase circulating process fluid into multiple compression steps into individual pressure stages, i.e., from the lowest pressure of the circulating process in the evaporator pressure stage to the highest required pressure of the first pressure stage built on top of each other, the desired temperature lift can be configured very variably between the lowest available heat source temperature and / or waste heat temperature and the highest required sink temperature. This reduces the required pressure ratio for each compression step, i.e., the quotient of the resulting compression pressure relative to the inlet pressure before compression. This results in significantly less superheat of the compressed circulating process fluid above the condensation temperature when the compression pressure is achieved, conventionally expressed in Kelvin, than in the case of a single-stage compression from the lowest to the highest pressure in the circulating process. Therefore, depending on the choice of circulating process fluid and the location of its critical point and two-phase region, very high end pressures can be achieved, allowing correspondingly high condensation temperatures and enthalpies of condensation for transferring process heat to the heat sink. Thus, particularly with water as the circulating process fluid, condensation conditions are possible up to at least about 250° C., for example, at only 40 bar.

[0078] The variably scalable heat pump device and the widely configurable heat pump device structure allow the range of use to be extended to generate process heat at temperature levels up to 250°C with a temperature lift of approximately 200 Kelvin at a heat coefficient of performance greater than 2.5, while maintaining the use of waste heat at temperatures below 60°C-80°C, and in this case the process heat can also be simultaneously released at multiple temperature levels of different heights, for example, between 100°C and 250°C.

[0079] Such a multi-stage design is advantageous for several reasons. First, it reduces overheating during compression. This is not a thermal advantage, but rather eliminates the need for lubrication of pistons or other sliding surfaces, for example in high-pressure compressors based on the displacement principle, thus allowing for an oil-free and simple construction of the compressor and extending the field of application to hygienic steam.

[0080] On the other hand, it is possible to create a branch in the circulation process that allows the utilization of process heat at different temperature levels, not only for the generation of the highest value process heat for the highest required sink temperature, but also for heat sinks with lower required sink temperatures, by supplying process heat generated at the lower condensation temperature of the circulating process fluid in a second, third, fourth, and / or other pressure stage. This reduces the overall dissipation of specific exergy, since less specific compression work is required for low-value process heat than for high-value process heat. The construction with more than three pressure stages and the separate generation of process heat of different values ​​at different temperature levels generally improves the heat performance coefficient of the heat pump process.

[0081] Thus, liquid circulating process fluid from a lower pressure stage can be introduced upstream of the highest pressure compressor, which then functions as a wet vapor compressor, or downstream of the highest pressure stage, for example if a further mixing separator follows the highest pressure stage, thereby producing nearly saturated vapor of the highest pressure stage. In this case, liquid condensate from any of the relatively low pressure stages (i.e., not just from the lowest stage above the evaporator) can be used to saturate the compressed vapor of the highest pressure stage.

[0082] In a further embodiment of the heat pump device, one mixing separator or two or more mixing separators are connected upstream of a first mixing separator, and the vaporous circulating process fluid of each upstream connected mixing separator can be supplied to the subsequent mixing separator via a compressor connected downstream, and / or the liquid circulating process fluid can be returned from each downstream connected mixing separator having a higher pressure and / or a higher temperature than in the upstream connected mixing separator.

[0083] This provides a heat pump apparatus in which the vaporous circulating process fluid of at least one of the second, third, fourth and / or further pressure stages condenses in at least one heat exchanger of at least a second heat sink to indirectly transfer heat to said heat sink, and in which the circulating process fluid condensed in the heat exchanger of the second or further heat sink of said second, third, fourth and / or further pressure stage flows into a mixing separator of a respective lower pressure stage, i.e., the third, fourth, fifth and / or further pressure stage, having a pressure less than the pressure of the circulating process fluid condensed in the heat exchanger.

[0084] Thus, the heat pump device allows for an extended heat pump circulation process based on a circulation process including at least four pressure stages with different pressure levels, i.e. at least one first pressure stage, at least one second pressure stage, at least one third pressure stage, and at least one lowest pressure stage in the heat pump circulation process at the evaporator pressure, whereby the heat pump device can be easily scaled and variably configured by supplementing the circulation process by further pressure stages, i.e., the fourth, fifth, sixth and / or further pressure stages, with corresponding mixing separators and compressors, in order to adapt the overall achievable temperature lift as required.

[0085] In a heat pump system with staged compression, the vapor-phase circulating process fluid is compressed from the mixing separator of each pressure stage to a higher pressure stage in each compression step, where it is superheated due to the polytropic compression. After compression, the superheat present in the vapor-phase circulating process fluid at the inlet connection for the mixing separator assigned to a subsequent pressure stage is used to evaporate a predetermined proportion of the liquid-phase circulating process fluid that flows in through the inlet connection for the mixing separator of the pressure stage achieved by the upstream compression. This evaporated proportion is supplied to the already vapor-phase flow rate of the circulating process fluid in the compression path of this pressure stage without compressor work. This increases the condensation enthalpy of the vapor-phase circulating process fluid available as process heat overall at this pressure stage, while the compressor work thus far remains constant. This increases the heat coefficient of performance.

[0086] A further advantage of heat pump systems with staged compression is the use of a circulating process fluid to reduce the superheat that occurs due to the compression, since the circulating process fluid has already been treated or at least descaled once for the initial filling of the heat pump system and is reused due to the closed circulation process, so that continuous water consumption by injecting tap water or other lime-containing water and the resulting inevitable lime deposits are completely avoided compared to the prior art.

[0087] A further advantage of heat pump systems with staged compression is that the condensed circulating process fluid is cooled stepwise throughout the circulating process by releasing the pressure in each lower pressure stage, fully utilizing the enthalpy contained in the lower pressure stages, which is added to the vapor mass flow of each lower pressure stage without compressor work in order to additionally evaporate the liquid circulating process fluid as an additional saturated vapor fraction in each case, thereby further increasing the heat coefficient of performance.

[0088] A further advantage of heat pump systems that gradually cool the condensed circulating process fluid in individual pressure stages is that the amount of vaporous circulating process fluid increases significantly along the pressure rise in the compression path during the gradually increasing compression, so that in the evaporator, significantly less liquid circulating process fluid needs to be evaporated than must be provided to heat the heat sink for condensation. As a result, only a significantly smaller mass flow of the vaporous circulating process fluid needs to be transported through the evaporator, and due to the larger specific volume of the vaporous circulating process fluid at lower pressures in the compression path, it can be compressed in succession in compressors that typically have the largest overall size. This allows the overall size of the system to be significantly reduced without any loss of power.

[0089] In order to improve the return conduction of the circulating process fluid condensed in at least one heat exchanger from the first pressure stage and / or the further pressure stages, a condensate separator is connected downstream of each of the at least one heat exchanger and / or a condensate separator downstream of each of the second heat exchanger and / or a condensate separator downstream of each of the further heat exchangers in order to return the condensed circulating process fluid from the first pressure stage into the first mixing separator and / or to return the condensed circulating process fluid from the second or third pressure stage, in particular from the respective lower pressure stage, into the upstream-connected mixing condenser.

[0090] In a further embodiment of the heat pump device, downstream of the fourth connection is arranged a condensate separator for guiding the condensed circulating process fluid of the first mixing separator, of the upstream connected mixing separator and / or for guiding the condensed circulating process fluid back into the upstream connected mixing separator or into the evaporator, respectively.

[0091] In order to generate a mixed vapor of one pressure stage and for this purpose to draw in suction vapor from a lower pressure stage or the pressure stage of the evaporator, the first compressor is configured as a thermal compressor, whereby by means of the thermal compressor the vaporous circulating process fluid of the first pressure stage as motive vapor can be mixed with the vaporous circulating process fluid from the evaporator as suction vapor and supplied as compressed mixed vapor to the first mixing separator or to a first mixing separator connected upstream.

[0092] Therefore, the compressor connected upstream of the mixing separator of each pressure stage is configured as a thermal compressor, so that by means of the thermal compressor the vaporous circulating process fluid of the higher pressure stage as motive vapor can be mixed with the vaporous circulating process fluid of the lower pressure stage as suction vapor and supplied as compressed mixed vapor to the mixing separator of this pressure stage.

[0093] In a thermal compressor, a flow or partial flow of the vaporous circulating process fluid of the first or further pressure stage is used as motive steam, which reaches a high speed in the thermal compressor and thereby, due to the Venturi or Coanda effect, draws in suction steam in the form of vaporous circulating process fluid at a lower pressure than the motive steam, in which case the motive steam and suction steam are then mixed to form a mixed steam having a pressure higher than that of the suction steam and a pressure of the pressure stage having a pressure lower than that of the motive steam.

[0094] In a further embodiment of the heat pump device, a further compressor of the first pressure stage or the second pressure stage or a further pressure stage is arranged upstream of the thermal compressor, so that the compressed vaporous circulating process fluid, in particular the vaporous circulating process fluid leaving the first pressure stage and further compressed to the pressure of the motive vapor pressure stage, can be used as motive vapor.

[0095] To achieve wet vapor compression or dry compression, another mixing separator is connected downstream of the first mixing separator in the second pressure stage, where this other mixing separator is located in the first pressure stage.

[0096] The downstream connected mixing separator of the first pressure stage may or may not have a downstream connected compressor.

[0097] In a further embodiment, the heat pump device comprises an open-loop and / or closed-loop control device for open-loop and / or closed-loop control of the components of the heat pump device and optionally at least one heat source and / or at least one heat sink.

[0098] This allows for open-loop and / or closed-loop control of the heat pump device and its process heat supply with as low a drive power as possible and as high an energy efficiency as possible by closed-loop control of the pressure and temperature of the individual pressure stages using closed-loop control of the compressor and the heating power of the heat source and closed-loop control of the flow rate of the condensed circulating process fluid at the inlet to the individual mixing separators and / or compressors. Thus, partial processes contained in or connected to the heat pump device or even the entire process of the heat pump device can be managed and regulated by at least one open-loop and / or closed-loop control device.

[0099] In order to guide the condensed circulating process fluid in the form of droplets back into each mixing separator, the second connection for the inflow of the condensed circulating process fluid has a spraying device for spraying the circulating process fluid in liquid form flowing into the first mixing separator or into each mixing separator.

[0100] The spraying device may be, for example, a spray nozzle, which sprays the incoming liquid circulating process fluid in the form of droplets into the mixing separator while creating a pressure drop, and a part of the liquid circulating process fluid flowing in at the second connection for the inflow of the liquid circulating process fluid evaporates depending on its temperature, thereby reducing the superheat of the vapor circulating process fluid flowing in from the first connection.

[0101] In another aspect of the invention, the problem is solved by a drying apparatus for drying an article to be dried with a heated process gas flow, the drying apparatus having a heat pump device as described above, whereby the process gas flow can be heated on the heat release side of the heat pump device as a heat sink.

[0102] Thus, process heat at high temperature levels up to 250° C. can be used for heating the process stream of the dryer.

[0103] In an additional aspect of the present invention, the object is to provide a method for operating a heat pump device as described above for the energy-efficient generation of process heat, in particular in the temperature range of 100°C to 250°C, comprising the following steps: - heating the liquid circulating process fluid by indirect heat supply from a heat source and evaporating the liquid circulating process fluid in an evaporator at a pressure stage of the evaporator; compressing the vaporous circulating process fluid to a second pressure stage by a first compressor; - feeding the compressed vaporous circulating process fluid to at least one mixing separator of a second pressure stage; - feeding the vaporous circulating process fluid exiting the at least one mixing separator to at least one second compressor for compressing the vaporous circulating process fluid from the second pressure stage to the first pressure stage; - transferring process heat of the compressed vaporous circulating process fluid of the first pressure stage to at least one heat sink, optionally associated with the process fluid; and optionally directing the condensed circulating process fluid of the first pressure stage back into at least one mixing separator, This is solved by a method comprising:

[0104] Further embodiments of the method use water, alcohol, and / or water-soluble organic substances as the circulating process fluid.

[0105] Preferably, the heat pump device operates using water (chemical formula HO) as the circulating process fluid, which is natural and completely environmentally friendly. Similarly, the heat pump device can also operate with alcohol and / or an aqueous solution of alcohol as the circulating process fluid. Aqueous solutions of water-soluble organic substances and / or one or more organic substances can also be used as the circulating process fluid. Similarly, any combination of water, alcohol, and / or water-soluble organic substances can be used as the circulating process fluid.

[0106] As alcohols, for example, methanol, ethanol, propanol can be used, and as organic substances, esters and / or ethers can be used.

[0107] In a further embodiment of the method, a pressure boost can be carried out by a condensate pump on the stream of condensed circulating process fluid leaving the at least one mixing separator, in particular at a pressure stage higher than the pressure stage of the evaporator, and this stream can then be mixed with a stream of liquid circulating process fluid that has been indirectly heated beforehand in a heat exchanger of the heat source, and the mixed stream can be used for indirect heating of the evaporator, after which the mixed stream in particular is guided back into the evaporator again.

[0108] In a further embodiment of the method, pressure boosting is performed on the stream of condensed circulating process fluid exiting the at least one mixing separator by means of at least one condensate pump, and the stream is then introduced into the vaporous circulating process fluid from the at least one mixing separator to produce circulating process fluid wet vapor, which is then compressed to a first pressure stage in a compressor connected downstream.

[0109] The present invention will now be illustrated by the following examples. [Brief explanation of the drawings]

[0110] [Figure 1] 1 shows a highly schematic diagram of a heat pump device with an evaporator, a first compressor, a second pressure stage mixing separator, a second compressor and a first pressure stage heat exchanger. [Figure 2] 2 shows, in a highly schematic manner, an alternative to the heat pump device shown in FIG. 1 with heating of the evaporator via a circuit through a heat exchanger of the heat source. [Figure 3] 3 shows, in a highly schematic manner, an alternative to the heat pump arrangement shown in FIG. 2, with an additional mixing separator after compression to the first pressure stage. [Figure 4] FIG. 4 is a highly schematic illustration of an alternative to the heat pump apparatus shown in FIG. 3, including a thermal compressor for compressing the vaporous circulating process fluid from the evaporator pressure stage to the second pressure stage, supplied with motive vapor from the first pressure stage. [Figure 5] FIG. 5 is a highly schematic illustration of an alternative to the heat pump apparatus shown in FIG. 4, including a thermal compressor for compressing the vaporous circulating process fluid from the evaporator pressure stage to a second pressure stage, supplied with motive vapor from the motive vapor pressure stage. [Figure 6] 4 shows, in a highly schematic manner, another alternative to the heat pump arrangement shown in FIG. 3, with an additional third pressure stage. [Figure 7]7 shows, in a highly schematic manner, an alternative to the heat pump arrangement shown in FIG. 6, which additionally transfers process heat of the second pressure stage in a heat exchanger of a second heat sink. [Figure 8] 7 shows, highly diagrammatically, another alternative to the heat pump arrangement shown in FIG. 6, with an additional fourth pressure stage. [Figure 9] 10 is a highly schematic illustration of an alternative to the heat pump apparatus shown in FIG. 8, including a thermal compressor for compressing the vaporous circulating process fluid from the evaporator pressure stage to a fourth pressure stage, supplied with motive vapor from the motive vapor pressure stage. [Figure 10] 9 shows, in a highly schematic manner, another alternative to the heat pump arrangement shown in FIG. 8, which additionally transfers process heat of the second pressure stage in a heat exchanger of a second heat sink. [Figure 11] 11 is a highly schematic diagram illustrating another alternative to the heat pump apparatus shown in FIG. 10, transferring process heat from a third pressure stage rather than a second pressure stage in the heat exchanger of the second heat sink. [Figure 12] FIG. 2 is a diagram schematically illustrating a mixing separator of the heat pump device.

[0111] The heat pump apparatus 1 shown in Figure 1 comprises an evaporator 200 with heating via a heat source supply 14 and a discharge 15, a compressor 401 from the pressure stage of the evaporator 200 to a second pressure stage, a mixing separator 400 of the second pressure stage, a compressor 501 from the second pressure stage to the first pressure stage, a heat exchanger 520 as a first heat sink for transferring process heat of the first pressure stage, and an inlet 10 and an outlet 11 of a drying apparatus 5 as a heat sink. The heat pump apparatus 1 comprises an open-loop / closed-loop control unit 2 for open-loop and closed-loop control of the functions and components of the heat pump apparatus 1.

[0112] The second pressure stage mixing separator 400 has an inlet connection 406 for the vaporous circulating process fluid, an inlet connection 407 for the liquid circulating process fluid, a connection 408 for the vaporous circulating process fluid outlet 409, and an outlet connection 409 for the liquid circulating process fluid. The inlet connection 407 for the liquid circulating process fluid is equipped with an injection device for injecting the liquid circulating process fluid into the mixing separator 400 in the form of droplets while creating a pressure drop, so that part of the liquid circulating process fluid entering at connection 407 evaporates depending on its temperature, thereby reducing the superheat of the vaporous circulating process fluid entering at connection 406.

[0113] Under the lowest pressure of the circulation process in the evaporator 200, usually a partial vacuum below atmospheric pressure, and simultaneously the lowest temperature of the circulation process, the liquid circulation process fluid returned from the second pressure stage mixing separator 400 is heated and evaporated by the heat source via the supply 14 and the discharge 15, and then the vapor circulation process fluid as dry vapor is compressed from the evaporator pressure stage to the second pressure stage in the compressor 401, superheated and flows into the second pressure stage mixing separator 400.

[0114] From the mixing separator 400, the vaporous circulating process fluid leaves as dry vapor of the second pressure stage, which before compression in the compressor 501 is over-saturated via the condensate pump 250 with injected condensate and thus liquid circulating process fluid, thereby converting it into wet vapor with a proportion of liquid circulating process fluid, whereby during subsequent compression in the compressor 501 to the first pressure stage, this liquid proportion evaporates, and from the compressor 501 leaves the dry saturated vaporous circulating process fluid of the first pressure stage. In the heat sink heat exchanger 520, process heat at the condensate temperature of the first pressure stage is transferred from the vaporous circulating process fluid to the heat sink with inlet 10 and outlet 11, where the circulating process fluid condenses. The liquid circulating process fluid exits heat exchanger 520 at approximately the condensation temperature through condensate separator 522 in the first pressure stage and is introduced into mixing separator 400 of the second pressure stage, where it is expanded and cooled to the condensation temperature of the second pressure stage. In this case, a portion of the liquid circulating process fluid exiting heat exchanger 520 evaporates to form vapor circulating process fluid in the second pressure stage. Another liquid portion of the circulating process fluid exiting heat exchanger 520 evaporates depending on the degree of superheat of the vapor circulating process fluid entering mixing separator 400 from compressor 401. The remaining liquid portion of the circulating process fluid exiting heat exchanger 520 and introduced into mixing separator 400 is considered excess liquid circulating process fluid and exits mixing separator 400 at the pressure and condensation temperature of the second pressure stage, before being introduced back into evaporator 200.

[0115] In the alternative shown in Figure 2, the heat pump device 1 includes an indirect heating of the evaporator 200 via circulation through the heat exchanger 220 of the heat source (14, 15), and unlike the one shown in Figure 1, the flow rate of condensed circulating process fluid from the mixing separator 400 of the second pressure stage is introduced into the flow rate of liquid circulating process fluid previously heated indirectly in the heat exchanger 220 of the heat source, and the mixture of both flows is used to indirectly heat the evaporator 200. To overcome the pressure difference at the outlet from the second pressure stage to the circulation with the circulation pump 222, a condensate pump 201 is used.

[0116] Furthermore, the heat pump apparatus 1 shown in FIG. 2 differs from that shown in FIG. 1 in that the condensed circulating process fluid from the second pressure stage is introduced from the second pressure stage mixing separator 400 into the vaporous circulating process fluid of the second pressure stage to produce circulating process fluid wet vapor, which is then compressed to the first pressure stage in the compressor 501. In this case, the condensate pump 201 pumps an amount of condensed circulating process fluid exiting the mixing condenser 400 of the pressure stage next higher than the pressure stage of the evaporator 200. At the same time, the condensate pump 201 provides sufficient injection pressure for the liquid circulating process fluid of the second pressure stage before compression 501 to the first pressure stage. In other respects, the heat pump apparatus 1 shown in FIG. 2 operates in the same manner as described above.

[0117] The alternative heat pump device 1 shown in Figure 3 differs from that shown in Figure 2 in that the vaporous circulating process fluid after compression 501 from the second pressure stage to the first pressure stage and the condensed circulating process fluid of the second pressure stage are simultaneously introduced into the mixing separator 500 of the first pressure stage, thereby reducing superheating of the vaporous circulating process fluid during compression without prior injection of liquid circulating process fluid, and providing saturated vapor of the first pressure stage at the outlet 508 from the mixing separator 500.

[0118] In a minimum configuration of the heat pump device 1, which includes at least three pressure stages according to Figure 1, 2 or 3 and preferably uses water as the circulating process fluid, the evaporator 200 can be operated at an evaporation temperature of, for example, 54°C, using waste heat having a temperature of, for example, 60-80°C, which corresponds to an evaporation pressure of the circulating process fluid of 150 hPa. This evaporation pressure defines the operating conditions on the heat absorption side of the circulating process and corresponds to the lowest condensation pressure of the circulating process fluid within the circulating process, which condensation pressure also corresponds to the lowest pressure stage of the heat pump device 1.

[0119] Starting from this lowest pressure stage in the evaporator 200, the vaporous circulating process fluid, e.g., water, is compressed to a second pressure stage in at least one compressor 401. The pressure of the second pressure stage depends on the achievable compression ratio of the selected compressor 401, which may be, for example, in the range of 1.2 to 6.0. Depending on the compressor configuration, different intensities of heating of the vaporous circulating process fluid occur during compression.

[0120] Starting from an evaporation pressure of 150 hPa of the circulating process fluid in evaporator 200 and a compression ratio of, for example, 3.0 in compressor 401, the pressure in the second pressure stage would be calculated to be around 450 hPa. For the circulating process fluid, water, the boiling point and condensation temperature corresponding to 450 hPa in the second pressure stage is 78.7°C.

[0121] If we compare these two pressure stages (150 hPa; 54.0 °C) and (450 hPa; 78.7 °C) with an isentropic compression from the evaporator pressure stage (150 hPa; 54.0 °C) to a second pressure stage with 450 hPa, for example, where n = K = 1.333, which corresponds to a compression ratio of 3.0, then the temperature after isentropic compression is T V2 = 157.4 °C, which is the corresponding condensation temperature of the second pressure stage, T D2 =78.7℃, T V2 -T D2 =157.4℃-78.7℃=78.7K indicating overheating.

[0122] This positive temperature difference of 78.7 K results in pressure stage p V2 The steam is compressed to a pressure of 10 ... D2 The corresponding boiling point T D2 This allows heat transfer to the liquid circulating process fluid equivalent to

[0123] This situation is utilized to transfer the superheat enthalpy resulting from compression into one pressure stage for evaporation of the liquid circulating process fluid in the same pressure stage, thus generating a higher proportion of vaporous circulating process fluid in this pressure stage, without the need to compress this additional vaporous proportion into this pressure stage by adjusting for mechanical work, i.e., by consuming exergy.

[0124] This is achieved by the vaporous circulating process fluid compressed to the second pressure stage in the compressor 401 flowing into the second pressure stage mixing separator 400 through the vaporous circulating process fluid inlet connection 406, where it is brought into direct contact with the liquid circulating process fluid of the second pressure stage present in the second pressure stage mixing separator 400.

[0125] Inside the second pressure stage mixing separator 400, a quasi-steady equilibrium is formed due to the direct contact of the vaporous circulating process fluid with the liquid circulating process fluid and the rapid heat and mass transfer processes due to the simultaneous condensation of the vaporous circulating process fluid and evaporation of the liquid circulating process fluid, and this quasi-steady equilibrium is assisted, for example, by the cyclone effect, which allows the vaporous circulating process fluid to be separated from the liquid circulating process fluid and simultaneously discharged separately from the second pressure stage mixing separator 400 at mutually separated connections 408, 409, in particular at least the vaporous circulating process fluid at connection 408 and the liquid circulating process fluid at least at connection 409.

[0126] The vaporous circulating process fluid exiting the at least one connection 408 of the second pressure stage mixing separator 400 is then compressed in at least one compressor 501 from the second pressure stage to the first pressure stage, and this first pressure stage vaporous circulating process fluid flows through the heat release side of the heat pump device 1, indirectly transferring process heat to at least one heat sink (10, 11) in a heat exchanger 520 and condensing therein.

[0127] Thus, the transfer of process heat in the heat pump apparatus 1 is achieved by condensing the vaporous circulating process fluid at at least the condensation pressure and corresponding condensation temperature of the first pressure stage, which depends on the achievable compression ratio of the selected compressor 501, which may be, for example, in the range of 1.2 to 6.0.

[0128] Starting from a second pressure stage pressure of 450 hPa and a compression ratio of, for example, 4.0 in compressor 501, the pressure in the second pressure stage is in this case around 1,800 hPa. Thus, for water, the circulating process fluid, the boiling point and condensation temperature corresponding to 1,800 hPa in the second pressure stage is 116.9°C.

[0129] During the transfer of process heat on the heat dissipation side of the heat pump device 1, the vaporous circulating process fluid of the first pressure stage condenses at 116.9°C in at least one heat exchanger 520 of the heat sink (10, 11), and the condensed circulating process fluid of the first pressure stage leaves the heat exchanger 520 at a temperature not substantially below the corresponding condensation temperature of the first pressure stage and flows into the mixing separator 400 of the second pressure stage at at least one connection 407, in which case the corresponding boiling point and condensation temperature of the second pressure stage, which is about 78.7°C, is significantly below the corresponding boiling point and condensation temperature of the first pressure stage, which is about 116.9°C.

[0130] Such temperature differences can cause spontaneous evaporation of a further proportion of the liquid circulating process fluid when the condensed circulating process fluid from the first pressure stage enters the mixing separator 400 of the second pressure stage, which, as described above, is at a pressure lower than that of the first pressure stage by the inverse of the compression ratio of the compressor 501.

[0131] In the case of such spontaneous evaporation, the excess enthalpy of the incoming liquid circulating process fluid at a relatively high temperature can be utilized as evaporation enthalpy until cooling to the corresponding boiling point and condensation temperature of the second pressure stage. With the stated temperature difference of 116.9°C - 78.7°C = 38.2 K and an assumed specific heat capacity of the liquid circulating process fluid of 4.186 kJ / kg·K, a specific evaporation enthalpy of approximately 2,313 kJ / kg is required for isobaric evaporation at the second pressure stage pressure of 450 hPa. With respect to the mass flow rate of the liquid circulating process fluid from the condensed circulating process fluid of the first pressure stage entering the mixing separator 400 of the second pressure stage through the inlet connection 407, the ratio of the specific enthalpies gives a mass ratio of additional evaporated circulating process fluid of (4.186 kJ / kg·K·38.2 K) / (2,313 kJ / kg)=0.069 kg / kg, without the need to compress this additional vaporous fraction in the second pressure stage, for example by adding mechanical work in a previous compression in compressor 401.

[0132] The proportion of the liquid circulating process fluid that enters the mixing separator 400 of the second pressure stage at connection 407 and that is not evaporated to reduce superheat or by spontaneous evaporation is referred to as the surplus proportion of the liquid circulating process fluid of the second pressure stage, and leaves the mixing separator 400 at connection 409, from which at least a portion is further sent directly or indirectly into the evaporator 200.

[0133] The following describes the heat pump device 1 shown in FIGS. 1 to 3 with respect to the above-mentioned minimum configuration, with the heating coefficient of performance COP achievable when the circulating process fluid is water. h and the energy efficiency that can be achieved thereby.

[0134] The specific enthalpy of condensation corresponding to the first pressure stage (1,800 hPa; 116.9° C.) is 2,213 kJ / kg, which is an indication of the process heat that can be transferred to the heat sink (10, 11) on the heat release side of the heat pump device 1 at a corresponding condensation temperature of 116.9° C. Process heat transfer at a power of 1 MW therefore requires a mass flow rate of 1,628 kg / h of circulating process fluid of the first pressure stage, which condenses in the heat exchanger 520 and subsequently flows into the mixing separator 400 of the second pressure stage at connection 407 as liquid circulating process fluid at approximately 116.9° C.

[0135] To supply 1,628 kg / h of vaporous circulating process fluid of the first pressure stage, compression by compressor 501 from the second pressure stage (450 hPa; 78.7 °C) to the first pressure stage (1,800 hPa; 116.9 °C) is necessary. In principle, a distinction can be made between dry compression and wet vapor compression. In wet vapor compression according to FIG. 1 or FIG. 2, the outgoing mass flow already corresponds to the required supply mass flow of 1,628 kg / h of vaporous circulating process fluid of the first pressure stage, since so much liquid circulating process fluid is sprayed at the inlet of compressor 501 that the superheat generated during compression is reduced. In the case of dry compression, the compression superheat must be reduced in the subsequent first pressure stage mixing separator 500 according to FIG. 3 by injecting approximately 138 kg / h of liquid circulating process fluid from the second pressure stage mixing separator 400 into the first pressure stage mixing separator 500 and evaporating it based on the superheat of the dry-compressed vapor in compressor 501. This means that this 138 kg / h of liquid circulating process fluid does not need to be compressed in the first pressure stage by applying mechanical work in compressor 501. This means that the mass flow rate through compressor 501 only needs to be 1,628 kg / h - 138 kg / h = 1,490 kg / h. The power consumption of compressor 501 is approximately 131.6 kW.

[0136] This mass flow of 1,490 kg / h to be compressed in compressor 501 leaves connection 408 of mixing separator 400 of the second pressure stage. 1,628 kg / h of liquid circulating process fluid of the first pressure stage, condensed in heat exchanger 520, enters mixing separator 400 via connection 407, of which approximately 0.069 kg / h evaporates by spontaneous evaporation, i.e., approximately 112 kg / h of vapor circulating process fluid of the second pressure stage is generated by spontaneous evaporation. Of the approximately 1,516 kg / h of liquid circulating process fluid remaining in mixing separator 400, approximately 87 kg / h is required to reduce superheat due to compression to the second pressure stage, so the mass flow of vapor circulating process fluid in compressor 401 must be 1,490 kg / h - 112 kg / h - 87 kg / h = 1,291 kg / h. The power consumption of the compressor 401 is about 81.5 kW.

[0137] These 1,291 kg / h of vaporous circulating process fluid to be compressed in compressor 401 leave evaporator 200, where they are previously evaporated by indirect heating at the pressure stage of evaporator 200 (150 hPa; 54.0°C) with a power of approximately 848 kW. This heating power is made up of approximately 34 kW of heat recovery from connection 409 for the exit of the liquid circulating process fluid leaving mixer separator 400 and approximately 811 kW of waste heat from heat sources (14, 15).

[0138] In an alternative embodiment of the heat pump device 1 in a minimal structure with only a few main components according to Fig. 3, for the compression of the circulating process fluid in vapor form in the compressors (401, 501) and for the various pumps (201, 222, 251) for the circulating process fluid in liquid form, an overall power consumption of approximately 131.6 kW + 81.5 kW + 1.9 kW = 215 kW is consumed to provide 1,000 kW of process heat. Therefore, for a temperature lift of 116.9 °C - 60 °C = 56.9 K, the heating coefficient of performance COP h =4.65.

[0139] The compression by the corresponding compressors 301, 311, 401, 501, 601 in each alternative of the heat pump device 1 according to the present invention shown in Figures 1 to 11 generally indicates that the compression of the vaporous circulating process fluid by the corresponding compressors 301, 311, 401, 501, 601 is carried out by the performance of mechanical work with a compressor of a fluid mechanical configuration, for example an axial fan, radial fan, turbo compressor or turbine, or the compression of the vaporous circulating process fluid is carried out by the performance of mechanical work with a compressor of a displacement mechanical configuration, for example a piston compressor, rotary piston compressor or screw compressor.

[0140] An alternative to the heat pump device 1 shown in Figure 4 differs from Figure 3 in that the compression of the vaporous circulating process fluid by the compressor 401 is performed by a thermal compressor, for example a vacuum vapor injection pump, in which the vaporous circulating process fluid of a first pressure stage is used as the motive vapor, which reaches a high speed by thermal compression and thereby draws in, based on the Venturi effect or Coanda effect, suction vapor in the form of vaporous circulating process fluid at a lower pressure than the motive vapor, in which case the motive vapor and suction vapor are then mixed to form a mixed vapor at a second pressure stage having a higher pressure than the suction vapor but a lower pressure than the motive vapor.

[0141] 5 illustrates an alternative to the heat pump apparatus 1 shown in FIG. 4 , in which the vapor-phase circulating process fluid of the first pressure stage is further compressed in compressor 601, and the compressed vapor-phase circulating process fluid is used as motive vapor. This motive vapor reaches a high velocity when thermally compressed, and thereby draws in suction vapor in the form of vapor-phase circulating process fluid at a lower pressure than the motive vapor due to the Venturi or Coanda effect. In this case, the motive vapor and suction vapor are then mixed to form a mixed vapor having a pressure of the second pressure stage, which is higher than the suction vapor and lower than the motive vapor. Additionally, FIG. 5 illustrates introducing the condensed circulating process fluid of the second pressure stage from the second pressure stage mixing separator 400 into the vapor-phase circulating process fluid of the first pressure stage to generate circulating process fluid wet vapor, which is then compressed to the motive vapor pressure stage in compressor 601. At the same time, condensate pump 260 provides sufficient injection pressure for the liquid circulating process fluid in a second pressure stage before compression by compressor 601 to the motive vapor pressure stage.

[0142] The alternative to the heat pump system 1 shown in FIG. 6 differs from that shown in FIG. 3 in that it adds another third pressure stage including a mixing separator 300 and a compressor 301, in which the liquid circulating process fluid is introduced from the mixing separator (400, 500) of the second or first pressure stage into another mixing separator (300, 400) of the second pressure stage, the pressure and temperature of which are lower than those of the introduced liquid circulating process fluid. In this case, the condensate pump 201 pumps the amount of condensed circulating process fluid flowing out of the mixing condenser 300 of the next higher pressure stage than the pressure stage of the evaporator 200, unlike those shown in FIGS. 1 to 5. At the same time, compression from the lower pressure stage to the second pressure stage can be performed by the compressor 301 in the form of a fluid machine or displacement machine, or by a compressor in the form of a thermal compressor, similar to those shown in FIGS. 4 or 5.

[0143] In a further alternative of the heat pump device 1, the coefficient of performance can be improved by increasing the number of pressure stages, for example to at least four pressure stages as shown in Figure 6, for the same temperature lift. For example, instead of the first pressure stage (1,800 hPa; 116.9°C), the second pressure stage (450 hPa; 78.7°C), and the pressure stage of the evaporator 200 (150 hPa; 54.0°C) as shown in Figures 1 to 3, the stage difference can be reduced, for example, to the first pressure stage (1,800 hPa; 116.9°C), the second pressure stage (450 hPa; 78.7°C), the third pressure stage (225 hPa; 62.6°C), and the pressure stage of the evaporator 200 (150 hPa; 54.0°C). In this case, the heating coefficient of performance COP h = 4.71 because overall more exergy is recovered from the condensed circulating process fluid in more stages due to the reduced pressure difference between the pressure stages.

[0144] In a further alternative of the heat pump device 1, the number of pressure stages remains the same, for example as in the example according to Fig. 6, but the temperature lift can be increased by increasing the compression ratio of the individual compressors (301, 401, 501). For example, if the first pressure stage (4,044 hPa; 144.0°C), the second pressure stage (674 hPa; 88.9°C), the third pressure stage (225 hPa; 62.6°C) and the pressure stage of the evaporator 200 (150 hPa; 54.0°C) are adjusted, the heating coefficient of performance COP can be increased with a temperature lift of 114.0°C - 60°C = 84.0 K. h =3.44 is obtained.

[0145] In a further alternative to the heat pump device 1, for the same temperature lift and the same number of pressure stages, e.g., at least four pressure stages as in Figure 6, the coefficient of performance can be improved by splitting the transfer of process heat to a first heat sink and a second heat sink with different sink temperatures as in Figure 7. If all process heat is transferred to one combined sink temperature as in Figure 6, for example, the heating coefficient of performance COP h=3.44 can be achieved.

[0146] If a further alternative to the heat pump device 1 according to FIG. 7 is to split the process heat, for example, so that half is transferred to the first pressure stage and the other half to the second pressure stage by the heat exchangers 420, 520, then it is possible to reduce the maximum temperature lift of 84.0 K without having to reduce the COP h A heating coefficient of performance of 4.35 can be achieved.

[0147] The alternative heat pump device 1 shown in Figure 8 differs from that shown in Figure 6 in that another pressure stage having a mixing separator 310, a compressor 311 and a condensate separator 312 is added as a third pressure stage, thereby turning the third pressure stage of Figure 6 into a fourth pressure stage, in which the liquid circulating process fluid is introduced from the mixing separator 400 of the second pressure stage into the mixing separator 310 assigned to the third pressure stage, and the pressure and temperature of this third pressure stage are lower than the pressure and temperature of the liquid circulating process fluid introduced into the upper pressure stage.

[0148] The alternative to the heat pump device 1 shown in FIG. 9 differs from that shown in FIG. 8 in that the compression from the pressure stage of the evaporator 200 to the fourth pressure stage in the compressor 301 can also be carried out in a thermal compressor configuration similar to that shown in FIG. 4 or FIG. 5, which also advantageously applies to the compression steps between the other pressure stages.

[0149] 1 to 9, it is clear that the heat pump system 1 according to the present invention can be fundamentally variably configured with respect to the number of pressure stages, including the components and devices required for each pressure stage, and with respect to the choice of compressor configuration. For example, as shown in FIG. 9, the vapor circulating process fluid can be taken from the mixing separator 400 of the second pressure stage and compressed as motive vapor in the compressor 601 to compress the vapor circulating process fluid of any lower pressure stage, or, as shown in FIG. 9, the vapor circulating process fluid can be compressed as motive vapor by the compressor 601 starting from the second pressure stage by operating a vapor injection vacuum pump that compresses the vapor from the evaporator 200 to the fourth pressure stage.

[0150] In an alternative to the heat pump device 1 shown in Figure 10, unlike that shown in Figure 8, the vaporous circulating process fluid of the second pressure stage is condensed in at least one heat exchanger 420 of a heat sink having at least one inlet 12 and at least one outlet 13, thereby indirectly transferring heat to this heat sink, and in this case the circulating process fluid condensed in the heat exchanger 420 of the heat sink at the second pressure stage flows through at least one connection 317 into the mixing separator 310 of the third pressure stage, which has a pressure lower than the pressure of the circulating process fluid condensed in the heat exchanger 420.

[0151] In an alternative to the heat pump device 1 shown in Figure 11, unlike that shown in Figure 10, the vaporous circulating process fluid of the third pressure stage is condensed in at least one heat exchanger 420 of a heat sink having at least one inlet 12 and at least one outlet 13, thereby indirectly transferring heat to this heat sink, and in this case the circulating process fluid condensed in the heat exchanger of the heat sink at the third pressure stage flows through at least one connection 307 into the mixing separator 300 of the fourth pressure stage, which has a pressure lower than the pressure of the circulating process fluid condensed in the heat exchanger 420.

[0152] 10 and 11 show that at least one second temperature level, which is equal to the condensation temperature of the second or third pressure stage, in at least one heat exchanger 420 of a heat sink with at least one inlet 12 and at least one outlet 13 is provided for further process heat transfer to at least one further heat sink, so that the transfer of process heat at the at least one second temperature level already makes it possible to supply process heat up to a temperature close to the condensation temperature of the second or third pressure stage, so that only mechanical work is consumed for compression up to the second or third pressure stage.

[0153] For the transfer of the remaining process heat up to a temperature close to the condensation temperature of the first pressure stage, then only the difference in mechanical work for the compression already reached from the second or third pressure stage to this first pressure stage is still consumed, but the specific process heat and specific mechanical work required for compression are clearly smaller. By such staging in the provision of process heat, the specific exergy consumption in relation to the process heat transferred as a whole can advantageously be further reduced, which further improves the overall heating coefficient of performance.

[0154] In a non-illustrated alternative of the heat pump device 1, a further division into at least seven pressure stages is made, namely a first pressure stage (15,550 hPa; 200.0°C), a second pressure stage (3,390 hPa; 142.6°C), a third pressure stage (1,300 hPa; 107.0°C), a fourth pressure stage (441 hPa; 78.2°C), a fifth pressure stage (260 hPa; 65.8°C), a sixth pressure stage (180 hPa; 57.7°C) and a pressure stage of the evaporator 200 (150 hPa; 54.0°C), in which case there is already a temperature lift of 200.0°C - 60°C = 140.0 K, resulting in at least a coefficient of performance COP h= 2.48 is achievable. Again, the coefficient of performance can be improved by splitting the transfer of process heat, with the same temperature lift and number of pressure stages. For example, if the split is made so that half of the process heat is provided in the first pressure stage (15,550 hPa; 200.0°C) and the other half in the third pressure stage (1,300 hPa; 107.0°C), this will increase the heating coefficient of performance by about +40%, exceeding COPh = 3.40.

[0155] For the provision of process heat, by definition, an electrical power consumption as high as the product of the process heat and the inverse of the heating coefficient of performance is required. This means that to provide process heat at a temperature level of, for example, 200°C by the heat pump device 1, an electrical power consumption of just less than 0.3 kWel / kW of process heat is required, which corresponds to a reduction of more than 70% of the primary energy used by the heat pump device 1 and a 100% reduction of fossil fuel-based process heat generation.

[0156] The heat pump device 1 is highly energy efficient and is flexible, modularly expandable and adaptable to a wide variety of requirements regarding required sink temperature and / or other parameters. [Explanation of symbols]

[0157] 1. Heat pump equipment 2 Open-loop and closed-loop control units 5 Drying equipment 10 Inlet of first heat sink 11 Outlet of first heat sink 12 Inlet of second heat sink 13 Outlet of second heat sink 14 Heat source supply section 15 Heat source exhaust section 200 Evaporator 201 Condensate Pump 202 Regulating valve 220 Heat Source Heat Exchanger 222 Circulation Pump 250 Condensate pump for injection upstream of compressor 251 Condensate pump for injection upstream of the mixing separator 252 Regulating valve 260 Condensate pump for injection upstream of driven vapor compressor 300 Third pressure stage mix separator 301 Third pressure stage compressor 306 Connection for the inflow of circulating process fluid in vapor form 307 Connection for the inlet of condensed circulating process fluid 308 Connection for the outflow of vaporous circulating process fluid 309 Connection for outlet of condensed circulating process fluid 310 Mixing separator with different pressure stages 311 Compressor to different pressure stages 312 Condensate separator for separate pressure stage 316 Connection for the inflow of circulating process fluid in vapor form 317 Connection for the inlet of condensed circulating process fluid 318 Connection for the outflow of vaporous circulating process fluid 319 Connection for outlet of condensed circulating process fluid 320 Third pressure stage heat sink heat exchanger 322 Third pressure stage heat exchanger condensate separator 400 Second pressure stage mix separator 401 Compressor to pressure of second pressure stage 402 Second pressure stage condensate separator 406 Connection for the inflow of circulating process fluid in vapor form 407 Connection for the inlet of condensed circulating process fluid 408 Connection for the outflow of vaporous circulating process fluid 409 Connection for outlet of condensed circulating process fluid 420 Second pressure stage heat sink heat exchanger 422 Second pressure stage heat exchanger condensate separator 500 First pressure stage mix separator 501 Compressor to pressure of first pressure stage 502 First pressure stage condensate separator 506 Connection for the inflow of circulating process fluid in vapor form 507 Connection for the inlet of condensed circulating process fluid 508 Connection for the outflow of vaporous circulating process fluid 509 Connection for outlet of condensed circulating process fluid 520 First Pressure Stage Heat Sink Heat Exchanger 522 First pressure stage heat exchanger condensate separator 601 Compressors for generating motive steam

Claims

1. A heat pump device (1) for energy-efficient generation of process heat, comprising: The heat pump device (1) has a heat absorption side, a heat release side, a circulating process fluid, and an evaporator (200) on the heat absorption side; The heat pump device (1) can be arranged with at least one heat exchanger (520) and at least one heat sink (10, 11) on the heat release side, and at least one heat source (14, 15) on the heat absorption side; The evaporator (200) allows the liquid circulating process fluid to be indirectly heated by heat supplied from the corresponding heat sources (14, 15) and evaporated at a pressure stage in the evaporator (200), The heat pump device (1) has at least one first compressor (401) connected downstream of the evaporator (200), and the at least one compressor (401) is capable of compressing a vapor-state circulating process fluid from a pressure stage of the evaporator (200) to a second pressure stage, the heat pump device (1) comprises at least one first mixing separator (400) at the second pressure stage, the at least one first mixing separator (400) having a first connection (406) for the inflow of a circulating process fluid in vapor form, a second connection (407) for the inflow of a condensed circulating process fluid, a third connection (408) for the outflow of the circulating process fluid in vapor form and an optional fourth connection (409) for the outflow of the condensed circulating process fluid, downstream of the mixing separator (400) is connected at least one second compressor (501), so that the vaporous circulating process fluid leaving the third connection (408) can be compressed in the at least one second compressor (501) from the second pressure stage to the first pressure stage, and by means of the at least one heat exchanger (520) associated therewith, process heat can be transferred indirectly from the vaporous circulating process fluid of the first pressure stage to the at least one heat sink (10, 11) associated therewith, The circulating process fluid condensed in the at least one heat exchanger (520) can be returned via the second connection (407) into the at least one first mixing separator (400) of the second pressure stage, while at the same time vaporous circulating process fluid can be introduced into the mixing separator (400) from the at least one first compressor (401) via the first connection (406), in a heat pump device (1), At least one of the first mixing separators (400) has a fourth connection (409) for the outlet of condensed circulating process fluid, whereby the condensed circulating process fluid that flows out can be guided directly or indirectly back into the evaporator (200) and / or can be supplied into at least one of the second compressors (501).

2. The heat pump device (1) according to claim 1, wherein the heat pump device (1) has at least one heat exchanger (520) assigned to the first pressure stage and / or a heat exchanger (420) assigned to the second pressure stage and / or a heat exchanger (320) assigned to a pressure stage lower than the second pressure stage on the heat release side.

3. 3. The heat pump device (1) according to claim 1 or 2, wherein the heat pump device (1) comprises the at least one heat source (14, 15) and / or the at least one heat sink (10, 11).

4. 3. The heat pump device (1) according to claim 1 or 2, wherein the heat pump device (1) comprises a second mixing separator, a third mixing separator, a fourth mixing separator and / or optionally further mixing separators (300, 310), each of which has a further compressor (301, 311) connected upstream thereof.

5. 5. The heat pump device (1) according to claim 4, wherein one or more mixing separators (300, 310) are connected upstream of the first mixing separator (400), and the vapor-phase circulating process fluid of each of the upstream-connected mixing separators (300, 310) can be supplied to the subsequent mixing separator (310, 400) via a compressor (311, 401) connected downstream, and / or the liquid-phase circulating process fluid can be returned from each of the downstream-connected mixing separators (310, 400) having a higher pressure and / or a higher temperature than in the upstream-connected mixing separator (300, 310).

6. 3. The heat pump device (1) according to claim 1 or 2, wherein a condensate separator (522) is connected downstream of each of the at least one heat exchanger (520) and / or a condensate separator (422) is connected downstream of each of the second heat exchanger (420) and / or a condensate separator (322) is connected downstream of each of the further heat exchangers (320) for guiding condensed circulating process fluid from the first pressure stage back into the first mixing separator (400) and / or for guiding condensed circulating process fluid from the second or third pressure stage back into the upstream connected mixing condenser (300, 310).

7. 3. The heat pump device (1) according to claim 1 or 2, wherein downstream of the fourth connection (409) there is arranged a condensate separator (312, 402, 502) for guiding the condensed circulating process fluid into the upstream connected mixing separator (300, 310, 400) or back into the evaporator (200) for the outflow of the condensed circulating process fluid of the first mixing separator, of an upstream connected mixing separator and / or of each of the mixing separators (300, 310, 400, 500), respectively.

8. 3. The heat pump device (1) according to claim 1 or 2, wherein another mixing separator (500) is connected downstream of the first mixing separator (400) of the second pressure stage, and the other mixing separator (500) is arranged in the first pressure stage.

9. 3. The heat pump device (1) according to claim 1 or 2, comprising an open-loop and / or closed-loop control device (2) for open-loop and / or closed-loop control of components of the heat pump device (1) and optionally the at least one heat source (14, 15) and / or the at least one heat sink (10, 11).

10. 3. The heat pump device (1) according to claim 1 or 2, wherein the second connection (407) for the inflow of condensed circulating process fluid comprises a spraying device for spraying the liquid circulating process fluid flowing into the or each mixing separator.

11. 1. A drying apparatus for drying an article to be dried using a heated process gas flow, the drying apparatus comprising a heat pump device (1) according to claim 1 or 2, whereby the process gas flow can be heated on the heat release side of the heat pump device (1) as a heat sink (10, 11).

12. A method for operating a heat pump device (1) for energy-efficient generation of process heat, in particular in the temperature range of 100°C to 250°C, using a heat pump device (1) according to claim 1, comprising the following steps: heating a liquid circulating process fluid by indirect heat supply from a heat source (14, 15) and evaporating said liquid circulating process fluid in an evaporator (200) at a pressure stage of said evaporator (200); compressing the circulating process fluid in vapor form to a second pressure stage by a first compressor (301, 401); feeding the compressed vaporous circulating process fluid to at least one mixing separator (400) of a second pressure stage; feeding the vaporous circulating process fluid exiting the at least one mixing separator (400) to at least one second compressor (501) for compressing the vaporous circulating process fluid from the second pressure stage to the first pressure stage; transferring process heat of the compressed vaporous circulating process fluid of the first pressure stage to at least one associated heat sink (10, 11); and optionally directing the condensed circulating process fluid of the first pressure stage back to the at least one mixing separator (400); A method comprising:

13. 13. The method according to claim 12, wherein water, alcohol and / or water-soluble organic substances are used as circulating process fluids.

14. 14. The method according to claim 12 or 13, wherein the condensed circulating process fluid stream leaving the mixing separator (300, 400) is pressurized by a condensate pump (201), and then mixed with a liquid circulating process fluid stream previously indirectly heated in a heat exchanger (220) of a heat source (14, 15), and the mixed stream is used for indirect heating of the evaporator (200).

15. 14. The method according to claim 12 or 13, wherein pressure boosting is performed on the flow of condensed circulating process fluid leaving the at least one mixing separator (300, 400) by means of at least one condensate pump (201), and then said flow is introduced into the vaporous circulating process fluid from the at least one mixing separator (400) to produce circulating process fluid wet vapor, which is then compressed to a first pressure stage in the compressor (501) connected downstream.

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