An efficient heat pump-based heating system with a heat source

Abstract

The present invention relates to a heating system for generating steam comprising a heat pump system and an evaporation system for evaporating a food product, the heat pump system comprising a heat pump, operating with a primary fluid and a secondary fluid, the evaporation system comprising a heat treatment unit, a condenser and an evaporator, the heat treatment unit being configured to receive and transfer heat to a food product, the evaporator being configured to concentrate the food product. A method of concentrating food products in a heating system is also provided.

Description

[0001] Title of Invention

[0002] An efficient heat pump-based heating system with a heat source.

[0003] Technical Field

[0004] The present invention relates to a heating system for generating steam comprising a heat pump system and an evaporation system for evaporating a food product, the heat pump system comprising a heat pump, operating with a primary fluid and a secondary fluid, the evaporation system comprising a heat treatment unit, a condenser and an evaporator, the heat treatment unit being configured to receive and transfer heat to a food product, the evaporator being configured to concentrate the food product.

[0005] A method of concentrating food products in a heating system is also provided.

[0006] Background Art

[0007] Falling film evaporators are used to boil liquid under vacuum to concentrate it. While falling through tubes, the liquid is heated via steam and then boils. In Mechanical Vapor Recompression (MVR) evaporators, vapors of the boiling product are collected, separated, and recompressed in a mechanical compressor powered by electricity in order to be reused as heating steam.

[0008] In a typical situation, before entering the evaporator, the liquid undergoes a heat treatment unit connected to the evaporator. This heat treatment aims at reducing the bacteriological load in the product. In order to do so, the product could be elevated to a certain level of temperature by means of direct heating meaning steam is mixed into the product. This allows fast heating and greatly reduces product contact with surfaces which are potential source of fouling and biofilm formation during critical temperature. As steam is condensing into the product it needs to be “clean”, meaning free of hazardous chemicals and food-grade. Examples of contaminants could be: lubricating oils, Ammonia, Cyclohexylamine, Diethylaminoethanol, Hydrazine, Morpholine, Octadecylamine and Trisodium nitrilotriacetate.

[0009] In order to better control and adjust the behaviour of the evaporator or the thermal balance, some additional steam is often introduced in the system directly into the evaporator.

[0010] Finally, all vapors in excess are condensed in a condenser. The usual media to do so is a water loop connected to a moist air process, such as a cooling tower an evaporative condenser or an air cooler, to be able to exhaust the heat to the atmosphere.

[0011] An MVR evaporator uses electricity to be powered and evaporate water but still uses steam for heat treatment and control thermal balance. This steam is commonly generated in a steam boiler most frequently powered by gas combustion or other fossil fuels. The steam medium is most of the time mandatory to achieve a certain food quality in our applications (e.g. dairy food concentration) and therefore not replaceable by other heating media. Also, part of the problem, as steam ends up mixed with food product, it needs to be free of any potential hazardous chemical and be so called “clean” as mentioned above.

[0012] To battle the current climate crisis, it is desirable to design evaporation lines which are more energy efficient and not reliant on fossil energy carriers. The use of electrical steam boilers would be an easy solution to avoid relying on fossil fuels while maintaining currently available system designs, but it is not so efficient and entails higher operating costs compared to the conventional system. A heat pump system can provide both high efficiency (and potentially low operating costs) and independence from fossil fuels. However, conventional heat pumps work with hazardous chemicals (e.g. refrigerants, lubricant oils) that are not suited for generating food-grade steam in a conventional way. Moreover, they require specially designed systems for ensuring stability of operation.

[0013] The integration of an environmental friendly and energy efficient system may therefore entail some drawbacks especially in cases of food processing. Summary of the Invention

[0014] The present invention provides a heating system for generating clean steam by electricity means and in an efficient way, while recovering waste heat of the evaporator by means of a heat pump.

[0015] In a first aspect of the invention, this and further objects are achieved with a heating system of the kind mentioned in the introduction, which is furthermore characterized in that the evaporation system comprises at least one heat source for the heat pump, the heat source being a stream connected to or at an outlet of the evaporator; wherein the heat treatment unit is configured to transfer heat to the food product by means of direct heating via steam injection, wherein the steam injected is clean from hazardous chemicals and / or food grade; and wherein the heating system comprises a source circuit and a sink circuit, the source circuit being connected to the condenser, the sink circuit being connected to the heat pump, such that heat is transferred from the condenser to the sink circuit via the source circuit and the heat pump.

[0016] A main aspect of the invention is therefore to provide a system for guaranteeing generation of food-grade steam with a heat pump potentially working with hazardous chemicals.

[0017] The system may thus ensure independence from fossil fuels, high energy efficiency, generation of food-grade steam suitable for injection in liquid food and a stable operation of an evaporation line equipped with heat treatment at all stages of operation of said lines (e.g. production, start-up, cleaning-in- place (CIP)).

[0018] The system according to the invention may thus allow a full evaporator running only on electricity with potentially very low or even zero CO2 emissions and which may be more efficient than a simple electrical steam generator thanks to the recovery of waste heat. This system is especially suitable for the food industry, e.g. for the preparation of food products or food ingredients such as infant formula, skimmed milk, whole milk, whey proteins, lactose, coffee, juice to name a few, where the steam needs to be free of hazardous chemicals so it can be mixed with the food product. The food products or food ingredients need to undergo heat treatment most often in such systems. The food ingredient may be used in other industries, too, such as pharmaceutical.

[0019] The solution may also allow for continuous operation, even when the evaporator is in idle / start-up / CIP state thanks to, e.g., the buffer tank setup. Therefore, the production is not negatively affected compared to conventional systems relying on fossil-fuel fired boilers.

[0020] A stream is to be understood as a flow, preferably continuous, of a fluid, i.e. liquid, air or gas.

[0021] The heat pump may be replaced by a similar component in the system such as a chiller or a refrigerator.

[0022] In the heating system of the invention, the evaporation system comprises a heat treatment unit, the heat treatment unit being configured to receive and transfer heat to a food product. In general, a heat treatment unit comprises equipment that supplies heat to the food product, either directly via steam injection or indirectly, in order to elevate the temperature of the product, thus reducing the bacteria load.

[0023] Further, in the heating system of the invention, the evaporation system comprises an evaporator, the evaporator being configured to concentrate the food product. In general, a food evaporator is apparatus composed of one or several heat exchangers where the food product is heated and brought to its boiling point. Water is boiled out of the product thus concentrating it.

[0024] It will be understood that the reference to a conduit between the heat treatment unit and the evaporator and a conduit between the evaporator and the condenser means that there is a connection between the components. This may in some embodiments be a direct connection. However, in alternative embodiments the connection may be such that additional components are present in-between and the conduit thus goes via the additional component(s).

[0025] In a preferred embodiment, a standard dairy evaporation system is used, so that clean low-pressure steam can be generated and recompressed from the heat source of the evaporator, in a stable way, for all states of the evaporator. The condenser is configured to condense and remove vapor. The heat source of the heat pump connected at the outlet of the evaporator may be a source of waste heat.

[0026] In a preferred embodiment of the invention, the food product entering into the heat treatment unit is in a liquid state.

[0027] The heat treatment unit is configured to transfer heat to the food product by means of direct heating via steam injection, wherein the steam injected is clean from hazardous chemicals and / or food grade. The clean steam may be ensured by a separate water loop connected to the heat pump.

[0028] In an embodiment, the heating system further comprises one or more flash vessel or boiler configured to generate steam, the steam exiting the flash vessel or boiler being directed to the evaporator and / or to the heat treatment unit.

[0029] In an embodiment, the secondary fluid of the heat pump comprises water and / or the primary fluid of the heat pump comprises H2O, NH3, HFO (i.e. hydrofluoro-olefins), CO2 and / or hydrocarbon. Mixtures of the refrigerants or synthetic refrigerants may also be comprised in the primary fluid of the heat pump.

[0030] The heating system comprises a source circuit and / or a sink circuit, the source circuit being connected to the condenser, the sink circuit being connected to the heat pump, such that heat is transferred from the condenser to the sink circuit via the source circuit and the heat pump. Preferably, the source circuit and / or sink circuit operate with water as the operating medium.

[0031] The heat pump may preferably be an ammonia heat pump. The ammonia heat pump may cool a water circuit or source circuit that recovers waste heat from vapor at the evaporator condenser. Doing so, it heats up a water loop or sink circuit, that heats a separate “clean” secondary circuit or secondary loop. This hot water may subsequently be sent to low-pressure vessels where part of it vaporizes, turning to steam. That steam may either be sent to the evaporator as heating medium or recompressed and sent to the heat treatment section where it is mixed with the food product to heat it.

[0032] In an embodiment, the heating system further comprises a buffer tank, the buffer tank being connected to the secondary loop, the sink circuit and / or source circuit. On the hot water circuit, a tank may be placed to buffer evaporator and heat treatment small variations. On the cold water circuit, one or two tanks may be placed to generate a stock of hot water over time. That stock is available when the heat available (source) and the heat needed (sink) don’t match, i.e. transitory phases, start up, CIP of evaporator. An electrical booster or heater may be added to this stock to keep it warm when the evaporator stops. The electrical booster may be in connection with the buffer tank.

[0033] The heating system may thus provide the interdependency of heat sinks (heat demand) and heat sources (waste heat available) thanks to the buffer tank system and / or electrical booster.

[0034] In another embodiment, the heat pump system further comprises a heat exchanger connected to the heat pump, wherein the heat exchanger transfers heat from the sink circuit to a secondary loop, the secondary loop being connected to the heat treatment unit and / or evaporator, preferably via a flash vessel or boiler.

[0035] In an embodiment, the heat pump system further comprises a control device for controlling the operating medium connecting the secondary loop with the sink circuit, such that the secondary loop has a higher or lower pressure than the sink circuit. The control may be also performed based on pressure, temperature and / or flow. Preferably, the secondary loop may have a higher pressure than the sink circuit to allow steam being clean of or free of hazardous chemicals and food grade.

[0036] In an embodiment, the heating system further comprises one or more mechanical compressor(s) connected to the heat treatment unit, wherein the compressor is configured to compress steam and increase its temperature and pressure, such that the high temperature steam exiting the compressor is fed into the heat treatment unit. The mechanical compressor(s) may be positioned prior to the heat treatment unit, such that they compress steam and produce high-temperature steam before it is entered into the heat treatment unit and mixed with the food product.

[0037] In a further embodiment, wherein the heating system further comprises a heat rejection system, such as a cooling tower, and / or a heat exchanger, the heat rejection system and / or the heat exchanger being connected to the source circuit, the heat rejection system if or when present being configured to remove heat from the source circuit. In an embodiment, both a heat rejection system and a heat exchanger in the source circuit may be installed, while in another embodiment one of the heat rejection system or the heat exchanger may be installed.

[0038] The heat rejection system may be: an open type cooling tower, a close type cooling tower, cold water from various sources such as river water, well water; process water, “waste” water (condensates), an air cooler and / or a chiller.

[0039] In an embodiment, the heating system further comprises a heat exchanger being connected in parallel or in series with the condenser, the heat exchanger being further connected to the evaporator, such that the heat exchanger is configured to extract heat from the condensate of the food product exiting the evaporator.

[0040] In an embodiment, the secondary fluid is water, and wherein the heat pump system further comprises a make-up water unit connected to the heat pump and / or to the secondary loop, the make-up water unit being configured to compensate for water evaporated during steam generation in the flash vessel, in the boiler, or in the heat pump.

[0041] In an embodiment, the heating system further comprises an extraction pump connected to the flash vessel or boiler and a control device, the control device controlling the extraction pump, such that the extraction pump adjusts the flow, temperature and / or pressure of the operating medium.

[0042] According to a second aspect of the invention, a method of concentrating food products in a heating system is provided, the heating system comprising an evaporation system and a heat pump system, the heat pump system comprising a heat pump operating with a primary fluid and a secondary fluid, the evaporation system comprising a heat treatment unit, a condenser and an evaporator, the method comprising the steps of

[0043] - directing the food product into the heat treatment unit, the heat treatment unit transferring heat to the food product, - concentrating the food product in the evaporator,

[0044] - connecting the heat pump such that at least one heat source is a stream at an outlet of the evaporator.

[0045] The heating system of the second aspect of the invention is a heating system according to any embodiment of the first aspect of the invention.

[0046] Brief Description of Drawings

[0047] In the following description, embodiments of the invention will be described with reference to the schematic drawings, in which:

[0048] Fig. 1 shows a schematic view of a heating system in an embodiment of the present invention;

[0049] Fig. 2 shows a schematic view of a heating system in another embodiment of the invention;

[0050] Fig. 3 shows a schematic view of a heating system in yet another embodiment of the invention;

[0051] Fig. 4 shows a schematic view of a heating system in another embodiment of the invention;

[0052] Fig. 5 shows a schematic view of a heating system in yet another embodiment of the invention;

[0053] Fig. 6 shows a schematic view of a heating system in an alternative embodiment;

[0054] Fig. 7 shows a schematic view of a heating system in an embodiment; and

[0055] Fig. 8 shows a schematic view of a heating system in another embodiment.

[0056] Detailed description

[0057] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness.

[0058] Fig. 1 shows a schematic view of the main components of a heating system 1 comprising a heat pump system 2 and an evaporation system 4 for evaporating a food product. The heat pump system 2 comprises a heat pump 3, operating with a primary fluid and a secondary fluid. In this case, the primary fluid of the heat pump 3 comprises ammonia. The evaporation system 4 comprises a heat treatment unit 30, a condenser 6 and an evaporator 5. The heat treatment unit is configured to receive and transfer heat to a food product, the evaporator being configured to concentrate the food product inserted via inlet 13. The evaporation system 4 comprises at least one heat source 16 for the heat pump connected to an outlet of the evaporator 5. In this case, the heat source 16 is heat in the condenser 6. The food product entering into the heat treatment unit 30 is in a liquid state. The dashed lines represent the vapor phase. The heat treatment unit 30 is configured to transfer heat to the food product by means of direct heating via steam injection, wherein the steam injected is clean from hazardous chemicals and / or food grade.

[0059] The heat pump 3 transfers the waste heat from the evaporator’s condenser 6 via a cold loop or source circuit 17 to a hot water loop or sink circuit 18. The sink circuit 18 heats a separated secondary loop 20 via a heat exchanger 8. The water in the secondary loop 20 then flows into low-pressure vessels 7a, 7b, undergoing vaporization and generating clean steam. Having this separated secondary loop guarantees that the water that will vaporize and transform to steam remains free of any pollutant (or heat pump working fluid, lubricant oil etc.) in case of leakage from the heat pump. This is ensured by controlling that the “clean” secondary loop 20 is at higher pressure than the sink circuit 18 in this embodiment. Steam from low-pressure vessel 7a is then compressed with mechanical compressors 31 a, 31 b to achieve higher temperature steam and sent to the heat treatment unit 30. Steam from low- pressure vessel 7b directly feeds the evaporator 5.

[0060] To compensate for evaporator process perturbation, a hot buffer tank 12 is added in the clean secondary loop 20. A make-up water inlet 35 is present in the clean secondary loop 20 to compensate for the water evaporated during steam generation in the flash vessels 7a, 7b.

[0061] To thermodynamically balance the whole system, especially for startup phase and non-production phases such as cleaning-in-place steps where the system can be in either excess or deficit of energy, one hot buffer tank 12a and one cold buffer tank 12b are added in the source circuit 17, shown in Figs 2-8. These tanks can store warm water so that, with time, an energy stock is created when there is a surplus of energy in the system and is available when there is a deficit in a particular phase.

[0062] On the other hand, a heat rejection system which is a cooling tower 10 is connected to the source circuit via a heat exchanger 9 in this embodiment to remove heat when the system is in surplus of energy. When the system is stopped or idle for too long, meaning there is no waste heat to recover to generate steam, an electrical heater 21 can keep or heat the buffer tank 11 so that energy is available to initiate the system.

[0063] In the heating system shown in Fig. 1 , heat pump compressors, steam compressors and pumps are also included. These can be controlled in several possible ways. Some of the automation possibilities are listed below with reference to Figure 1 :

[0064] • The temperature of the steam going into the heat treatment unit 30 can be adjusted by acting on the compressor’s speed 31a, 31 b. The compressors’ speed would increase if a higher temperature at point A is needed (within the heat treatment section, e.g. product temperature). Other possibilities are to control them based on temperature or pressure at point B and / or C. These compressors could be controlled with same speed or with different speed.

[0065] • The flows of the steam going into the heat treatment unit 30 or to the evaporator 5 are controlled by adjusting flows in the flash vessels 7a, 7b by acting on pumps 27, 29 respectively. The pumps speed up if the flow needs to be increased.

[0066] • The extraction pumps 26, 28 can be controlled by setting a wished level of water in the flash vessels 7a, 7b. The extraction pumps 26, 28 speed up if the level increases. • The temperature in the clean secondary loop 20 is adjusted indirectly by the heat pump 3 through the heat exchanger 8 and flow of sink circuit 18. Several strategies could be implemented, for example: o The heat pump 3 can regulate for producing a fixed water temperature at point I, while the pump 25 can regulate the flow to ensure a temperature at point H. o The heat pump can regulate for producing a fixed water temperature at point H, while the pump 25 can regulate the flow to ensure a temperature at point I. o The heat pump can regulate for producing a fixed water temperature at point H, while the pump 25 can regulate the flow to ensure a temperature at point J. o The heat pump can regulate for producing a fixed water temperature at point H, while the pump 25 can work at fixed flow.

[0067] • The outlet temperature on the source side (point K) of the heat pump can be controlled by means of the pump 24. The pump increases flow if the temperature decreases. This pump can also work at fixed flow and the heat pump compressors can regulate for keeping a fixed temperature in point K.

[0068] • Pump 23 can be controlled for obtaining a setpoint steam temperature at point P. The pump increases speed if the temperature increases. Alternatively, it can control the temperature at point 0.

[0069] • The electrical heater 21 can be controlled by keeping a fixed temperature in point L or alternatively in point M (inside the tank 11 ).

[0070] • The energy absorbed by the external sink (e.g. cooling tower 10) can be controlled by means of the pump 22 that can regulate for ensuring a setpoint temperature at point N. The pump increases speed if the temperature in point N decreases.

[0071] A method of concentrating a food product in a heating system 1 is also shown in Fig. 1. The method comprises the step of directing the food product into the heat treatment unit 30 via the inlet 13. The heat treatment unit transfers heat to the food product via direct heating, i.e. steam injection. The food product is then concentrated in the evaporator 5, and a heat source 16 for the heat pump 3 is connected to an outlet of the evaporator 5. The heat source 16 may be heat extracted from the condenser 6 or heat from the condensate 15 exiting the evaporator 5.

[0072] Turning to Fig. 2, this embodiment shows a configuration of integration of additional sinks 32 and sources 33 in the proposed invention. Heat from additional sources 33 other than the vapor present in the condenser 6 of the evaporator may be integrated in various parts of the system, such as storing additional heat in a heat storage tank either in the source (cold) side or in the sink (hot) side of the heat pump 3, or by providing additional steam to the system. Such heat sources might be waste heat streams from other processes in the plant, or high value heat generated by e.g. electricity or fossil fuels. Example of additional sinks may be any processes in the plant, e.g. preheaters of concentration systems, pasteurizers etc. The presence of additional sources 33 increases the complexity of the system compared to the embodiment shown in Fig. 1 , as it includes an additional dependency to a process external to the evaporator. At the same time, it may provide potential advantages in terms of increased stability of the system and potentially in reducing or avoiding the heat storing capacity present in embodiment 1 .

[0073] Additional heat sinks may be integrated at different points as well, such as at the heat storage tank in the cold side of the heat pump, or in the hot side of the heat pump. This gives the opportunity of operating the system in a centralized heat pump system while maintaining all the advantages of the proposed system dedicated to the evaporator unit.

[0074] The embodiment of Fig. 3 shows an alternative configuration for extracting heat from the condensate 15 of the evaporator 5: instead of flashing such condensate in the condenser 6, it is here used in series to the condenser 6 to boost the temperature of the water. An additional heat exchanger 9 is thus included in the system, connected to the evaporator 5 and condenser 6. This may be beneficial for the heating system in terms of increased efficiency. However, heat exchanger 9 may be absent from the system. Furthermore, two heat sources 16 are included in the system: one heat source being the heat in the condenser 6 and another heat source being the heat of the condensate.

[0075] Fig. 4 shows an alternative configuration for extracting heat from the condensate of the evaporator: instead of flashing such condensate in the condenser, it is used in parallel to the condenser 6 to boost the temperature of the water. The additional heat exchanger 9 is connected with the evaporator 5 and the heat exchanger 9. This embodiment may be beneficial for reducing the size of the condenser 6 and increasing the heat recovered from the condensate (hence the overall efficiency) in the full evaporator system 4. Similarly, two heat sources 16 for the heat pump 3 are included in this system.

[0076] In Fig. 5, a different way of creating clean steam is shown in the system: instead of using flash tanks, boilers 7a, 7b are used. This allows to change the placement of the hydraulic separation and potentially increase the efficiency of the overall system.

[0077] Fig. 6 presents the use of a single flash tank 7a instead of multiple ones. This may allow lower CAPEX and potentially higher efficiency, but it may require a more complex control system. Similarly, also the boiler version shown in Fig. 5 can work with a single boiler.

[0078] An alternative way of automatically generating clean steam is also shown in Fig. 7. This is valid in the case in which the heat pump 3 is working with water as primary fluid and oil free compressors. In this case, the heat pump 3 may work in an open-cycle configuration, reducing the complexity of the system and its CAPEX and increasing the energy efficiency.

[0079] Lastly, Fig. 8 shows an alternative balancing sink 36 integrated in the source circuit 17, where no cooling tower or heat exchanger 9 is present. This shows that a cooling tower is not necessary per se, but it is important to have some means for rejecting extra heat. Having a heat exchanger in between is not necessary, and extra sinks can be integrated in many different ways as shown in Fig. 2. List of reference numerals

[0080] 1 Heating system

[0081] 2 Heat pump system

[0082] 3 Heat pump

[0083] 4 Evaporation system

[0084] 5 Evaporator

[0085] 6 Condenser

[0086] 7a Flash vessel I boiler

[0087] 7b Flash vessel I boiler

[0088] 8 Heat exchanger

[0089] 9 Heat exchanger

[0090] 10 Cooling tower

[0091] 11 Buffer tank

[0092] 12a Hot buffer tank

[0093] 12b Cold buffer tank

[0094] 13 Product inlet

[0095] 14 Product outlet

[0096] 15 Condensate outlet

[0097] 16 Heat source

[0098] 17 Source circuit

[0099] 18 Sink circuit

[0100] 19 Primary loop

[0101] 20 Secondary loop

[0102] 21 Electrical heater

[0103] 22 Pump

[0104] 23 Pump

[0105] 24 Pump

[0106] 25 Pump

[0107] 26 Extraction pump

[0108] 27 Extraction pump

[0109] 28 Extraction pump

[0110] 29 Extraction pump

[0111] 30 Heat treatment unit

[0112] 31a Steam compressor

[0113] 31 b Steam compressor

[0114] 32 Additional sink

[0115] 33 Additional source

[0116] 34 Heat exchanger

[0117] 35 Make-up water inlet

[0118] 36 Balancing sink

Claims

C L A I M S1 . A heating system for generating steam comprising a heat pump system and an evaporation system for evaporating a food product, the heat pump system comprising a heat pump, operating with a primary fluid and a secondary fluid, and at least one compressor, the evaporation system comprising a heat treatment unit, a condenser and an evaporator, the heat treatment unit being configured to receive and transfer heat to a food product, the evaporator being configured to concentrate the food product, there being a first conduit between the heat treatment unit and the evaporator and a second conduit between the evaporator and the condenser, wherein the evaporation system comprises at least one heat source for the heat pump being a stream connected to an outlet of the evaporator; wherein the heat treatment unit is configured to transfer heat to the food product by means of direct heating via steam injection, wherein the steam injected is clean from hazardous chemicals and / or food grade; and wherein the heating system comprises a source circuit and / or a sink circuit, the source circuit being connected to the condenser, the sink circuit being connected to the heat pump, such that heat is transferred from the condenser to the sink circuit via the source circuit and the heat pump.

2. A heating system according to claim 1 , wherein the food product entering into the heat treatment unit is in a liquid state.

3. A heating system according to claim 1 or 2, wherein the heating system further comprises one or more flash vessel or boiler configured to generate steam, the steam exiting the flash vessel or boiler being directed to the evaporator and / or to the heat treatment unit.

4. A heating system according to any of claims 1 to 3, wherein the secondary fluid of the heat pump comprises water and / or the primary fluid of the heat pump comprises H2O, NH3, HFO, CO2 and / or hydrocarbon.

5. A heating system according to claim 1 , wherein the source circuit and / or sink circuit operate with water as an operating medium.

6. A heating system according to claim 5, wherein the heat pumpsystem further comprises a heat exchanger connected to the heat pump, wherein the heat exchanger transfers heat from the sink circuit to a secondary loop, the secondary loop being connected to the heat treatment unit and / or evaporator, preferably via a flash vessel or boiler.

7. A heating system according to claim 6, wherein the heat pump system further comprises a control device for controlling the operating medium connecting the secondary loop with the sink circuit, such that the secondary loop has a higher pressure than the sink circuit.

8. A heating system according to any preceding claim, wherein the heating system further comprises a mechanical compressor connected to the heat treatment unit, wherein the compressor is configured to compress steam and increase its temperature and pressure, such that the high temperature steam exiting the compressor is fed into the heat treatment unit.

9. A heating system according to any preceding claim, wherein the heating system further comprises a buffer tank, the buffer tank being connected to the secondary loop, the sink circuit and / or source circuit.

10. A heating system according to any preceding claim, wherein the heating system further comprises a heat rejection system, such as a cooling tower, and / or a heat exchanger, the heat rejection system and / or the heat exchanger being connected to the source circuit, the heat rejection system, if present, being configured to remove heat from the source circuit.

11. A heating system according to any preceding claim, wherein the heating system further comprises a heat exchanger being connected in parallel or in series with the condenser, the heat exchanger being further connected to the evaporator, such that the heat exchanger is configured to extract heat from the condensate of the food product exiting the evaporator.

12. A heating system according to claim 4, wherein the secondary fluid is water, and wherein the heat pump system further comprises a make-up water unit connected to the heat pump and / or to the secondary loop, the make-up water unit being configured to compensate for water evaporated during steam generation in the flash vessel, in the boiler, or in the heat pump.

13. A heating system according to claim 3, wherein the heating systemfurther comprises an extraction pump connected to the flash vessel or boiler and a control device, the control device controlling the extraction pump, such that the extraction pump adjusts the flow, temperature and / or pressure of an operating medium.

14. A method of concentrating food products in a heating system, the heating system being a heating system according to any of claims 1 to 13, the heating system comprising an evaporation system and a heat pump system, the heat pump system comprising a heat pump operating with a primary fluid and a secondary fluid, the evaporation system comprising a heat treatment unit, a condenser and an evaporator, the method comprising the steps of:- directing the food product into the heat treatment unit, the heat treatment unit transferring heat to the food product,- concentrating the food product in the evaporator,- connecting the heat pump so that at least one heat source is a stream at an outlet of the evaporator.

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