Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
  • F25B9/002—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant
  • F25B9/008—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant the refrigerant being carbon dioxide
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B45/00—Arrangements for charging or discharging refrigerant
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
  • F25D16/00—Devices using a combination of a cooling mode associated with refrigerating machinery with a cooling mode not associated with refrigerating machinery
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
  • F25D3/00—Devices using other cold materials; Devices using cold-storage bodies
  • F25D3/10—Devices using other cold materials; Devices using cold-storage bodies using liquefied gases, e.g. liquid air
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B2309/00—Gas cycle refrigeration machines
  • F25B2309/06—Compression machines, plants or systems characterised by the refrigerant being carbon dioxide
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B7/00—Compression machines, plants or systems, with cascade operation, i.e. with two or more circuits, the heat from the condenser of one circuit being absorbed by the evaporator of the next circuit

Definitions

• the present invention relates to the field of the production of cold, including mechanical type and cryogenic type, and is particularly interested in applications in the field of food processing, such as freezing and freezing.
• Mechanical refrigerants have long used ammonia (NH 3 ) or HCFCs (hydrochlorofluorocarbons) or HFCs (hydro-fluoro-carbons) as the refrigerant.
• CO 2 can also be used as a two-phase refrigerant fluid in combination with a compression cycle using a refrigerant, for example ammonia.
• the new cascade system generations consist of two distinct compression assemblies: o the high-pressure circuit using as refrigerant ammonia or any other refrigerant suitable for cooling by the ambient environment or a cold source (temperature between 10 and 30 ° C) and the low pressure circuit using carbon dioxide to supply the evaporator producing the useful cold.
• mechanical cold generally means a cold production system using a condensable steam compression cycle, and a “cryogenic cold” system.
• EEMPLICITY KEY (RULE 26) a system producing cold from the phase change of a cryogenic fluid in an open circuit.
• cryogenic uses the frigories released by the phase change of a cryogenic fluid, for example the sublimation of the carbon dioxide or the vaporization of liquid nitrogen.
• This technology works with open circuit ie lost fluids. The amount of investment is thus minimized.
• the cold called “mechanical” uses the frigories released by the expansion of a refrigerant, for example carbon dioxide. This technology works in a closed circuit with a constant fluid load. The amount of investment is higher because it is necessary to provide the compression groups. It is conceivable that moving from a mechanical cold production system to a cryogenic system and vice versa, or mixing the two systems would provide the user with greater flexibility.
• any mechanical assembly requires periods of downtime to ensure their maintenance. It is generally accepted to stop the refrigeration production unit (ie the compressors) and the refrigeration system (the freezer) approximately 4 weeks per year to maintain the compressors and the various freezer components. During this maintenance period, the installation no longer produces.
• the possibility of working momentarily thanks to a cryogenic fluid would have the advantage of:
• cryogenic cold increases the cold production capacity of the mechanical system
• the final "wanted” cooling effect may be due to mechanical cold and cryogenic cold or only due to one of the two systems.
• the system that does not contribute directly to the “wanted” refrigeration effect is used to allow the other system to operate under extended conditions (power, temperature).
• the present invention seeks to provide a device in which, on the contrary, the "consumable" cryogenic fluid is CO 2 and is mixed with the fluid of the mechanical system which supplies the evaporator of the installation using cold to cool a thermal load.
• the latter fluid is also CO 2 whether it is the refrigerant "recycled” or the refrigerant fluid. This additional injection of CO 2 operates before producing cold in the evaporator.
• the proposed solution consists in mixing the fluids coming from an open circuit using CO2 as a cryogenic fluid and a closed circuit using CO2 as a refrigerant or as a refrigerant.
• the present invention relates to a method of refrigeration of one or more heat loads according to which there is a first source of CO 2 from a mechanical cooling system, and where one or more evaporators are fed to from this first source in order to carry out the evaporation of the CO 2 and thus cool said one or more heat loads, and characterized in that there is a second source of CO 2 , constituted by a cryogenic storage of CO2, and in that a supply of CO 2 is made from said second source, so that the flow of fluid supplying the evaporator or evaporators is a liquid CO 2 mixture from said first source and liquid CO 2 from said second source.
• a method of refrigerating one or more heat loads in which there is a first source of CO 2 from a mechanical cooling system, and where one or more evaporators are supplied from this first source to evaporation of the CO 2 therefrom and thereby cooling said one or more heat loads characterized in that a second source of CO 2 , constituted by a cryogenic storage of CO 2 , is available, and in that the a supply of CO 2 is made from said second source, so that the flow of fluid supplying the evaporator or evaporators is a mixture of liquid CO 2 from said first source and liquid CO 2 from said second source; source.
• the mechanical cooling system proceeds with the steps of:
• an amount of CO 2 substantially equivalent to that corresponding to said CO 2 supply is fed to the outside according to one or each combination in the following ways: i) the fluid or a part of the fluid obtained at the outlet of the evaporator (s) is directed towards said storage tank and from this tank is made the extraction and evacuation of said CO 2 flow to be discharged to the outside; j) the part of the fluid obtained at the outlet of the evaporator (s) is separated and discharged to the outside, the remainder being directed towards either said storage tank or towards said compression step; said supply of CO 2 from said second source is carried out in said storage tank where it is mixed with CO 2 originating from said evaporator or said expansion step.
• an amount of CO 2 substantially equivalent to that corresponding to said CO 2 supply is exhausted to the outside, one or each combined in the following ways: i) the fluid or a portion of the fluid obtained at the outlet of the evaporator (s) is directed towards a storage tank and is made from this reservoir the extraction and evacuation of said CO 2 flow to be discharged to the outside; j) the part of the fluid obtained at the outlet of the evaporator (s) is separated and evacuated to the outside, the remainder being directed towards either said storage tank or to a condensation stage by a a cold source produced by a vapor compression system and the liquid thus condensed is then stored in the storage tank; and one proceeds to said supply of CO 2 from said second source into the storage tank where it is mixed with CO 2 from the evaporator (s) or said condensation step.
• the amount of CO 2 present in the circuit is between two predetermined operating limits.
• the important point is to ensure that the amount of CO 2 present in the circuit does not increase to infinity without control (because of the contribution of CO2 of cryogenic origin) , which would be unimaginable, on the contrary the amount of CO 2 present in the circuit remains substantially constant or at least remains between two acceptable and predetermined operating limits. It is therefore necessary to evacuate towards the outside of the circuit a quantity of CO2 substantially equivalent to that which has been admitted into the circuit and which was of cryogenic origin.
• the whole of the fluid obtained at the outlet of the evaporator (s) (from the installation using cold to cool a heat load) can be sent to a non-cryogenic storage tank (tank from which the evaporators are fed), and realizes the reservoir extraction and evacuation of the flow to be discharged to the outside;
• the useful cold is produced by the evaporation of a CO 2 flow rate, resulting from the mixing of a flow rate from a cryogenic storage of CO 2 and a CO 2 flow rate obtained by a mechanical system. .
• the "global" CO 2 flow produces useful refrigeration in an evaporator located at the facility using cold to cool a load.
• the total flow of CO 2 is separated into two flow rates, one substantially equal to the flow rate that came from the cryogenic storage, the other equal to the flow rate that came from the mechanical cold.
• the regulation of the mixed cryogenic CO 2 flow rate and of the separated CO2 flow rate is carried out respectively by the opening of a supply valve from the storage and by the opening of the CO extraction valve. 2 .
• These valves are controlled for example:
• the flow rate which corresponds substantially to that which came from the cryogenic storage is evacuated directly into the atmosphere or indirectly through an oil separation phase if necessary.
• the coupling of the two circuits can be achieved in different ways, and in particular: 1. In the case where the CO? of the mechanical system is the fluid friqoriqangeange:
• the mixture of the two CO 2 flows can be achieved:
• the mixture of the two CO 2 flows can be achieved:
• the coupling of the two circuits must be regulated so that the amount of CO 2 present in the closed circuit remains substantially constant or at least between two acceptable operating limits.
• the mixed cryogenic CO 2 flow rate regulation and the separated CO 2 flow rate are achieved, for example, by the opening of a supply valve from the storage and by the opening of the CO 2 extraction valve.
• These valves can be ordered for example either:
• FIG. 1 is a schematic representation of an example of a mechanical cold system (two sets of compression);
• FIG. 2 is a schematic representation of a cryogenic cold system
• FIG. 3 is a schematic representation of an installation suitable for the implementation of the invention.
• FIG. 4 is a schematic representation of a second installation that is suitable for implementing the invention (mixing of the fluids coming from the open circuit using CO 2 as a cryogenic fluid and of the closed circuit also using CO 2 as a refrigerant fluid; -carrier).
• FIG. 5 is a schematic representation of a third installation suitable for the implementation of the invention.
• FIG. 6 is a schematic representation of a 4th installation suitable for the implementation of the invention.
• a thermal load for example a freezer
• the thermal load can be spread over several uses each having an evaporator (2) where the CO 2 produces a cooling effect by evaporation.
• the CO 2 heat exchanger / evaporator delivering the cold to the thermal load by evaporation of CO 2 and via an intermediate fluid (usually air), the evaporation of CO 2 typically takes place between 5, 2 bar and 26.5 bar and preferably between 5.5 bar and 10 bar.
• - In 3 a storage tank for CO 2 in the liquid phase; its operating pressure is that of the CO 2 evaporator, with the pressure drops close to it.
• - In 4 a CO 2 circulation pump for feeding the evaporator or evaporators.
• circuit breaker valves circuit breaker valves.
• a low-temperature vapor compression system using CO 2 as a refrigerant (the CO 2 vapors are compressed by the compressor 9 and are condensed in an evapo-condenser exchanger 10, at a temperature typically between -2O 0 C and -1O 0 C.
• the liquid obtained undergoes a loss of pressure in an expansion member 11 where a fraction of CO 2 vaporizes allowing cooling of the flow of CO 2 between -56 0 C and -1O 0 C
• the CO 2 obtained is accumulated in the tank 3 at the low pressure of the circuit.
• a high-temperature vapor compression system using a refrigerant such as ammonia (NH3), or HFC R404, R410, or any other fluid adapted to condense CO 2 by vaporizing (between -30 ° C); C and -5 0 C preferably) and condensing at the high pressure of the circuit between 15 0 C and 45 0 C preferably.
• a refrigerant such as ammonia (NH3), or HFC R404, R410, or any other fluid adapted to condense CO 2 by vaporizing (between -30 ° C); C and -5 0 C preferably) and condensing at the high pressure of the circuit between 15 0 C and 45 0 C preferably.
• a heat exchanger to condense the CO 2 by heat transfer to the high temperature circuit (the CO 2 condensing between -28 0 C and -10 0 C preferably).
• the thermal load to be cooled (1) is cooled by a cascade vapor compression cycle with CO2 at low temperature as the refrigerant.
• the advantage of a cascade is to achieve a high energy efficiency when the total temperature difference between the low temperature evaporator and the high temperature condenser is high.
• the evaporation temperature of the CO 2 is adjusted for the use of the required cooling between -56 ° C. and -1 ° C.
• the heat exchange between the CO 2 condenser and the evaporation of the high pressure circuit takes place at an optimized temperature depending on the refrigerant of the high temperature circuit and the total temperature difference and is generally between -28 0 C and -5 0 C.
• the CO 2 in the low temperature circuit circulates in closed circuit.
• cryogenic CO 2 storage tank at a pressure typically between 15 and 30 bar preferably.
• At 21 a valve regulating the flow of liquid CO 2 .
• At 22 an expansion member passing the CO 2 from the storage pressure to the operating pressure in the evaporator ie typically between 5.2 bar and 26.5 bar and preferably between 5.5 bar and 10 bar. bar.
• the CO 2 tank is used to supply one or more evaporators for cooling the thermal load or charges.
• the flow rate (s) are regulated according to a temperature or a pressure.
• the CO 2 evaporates in an evaporator or several between -56 0 C and -1O 0 C.
• the vaporized CO 2 is released into the atmosphere via an extraction duct.
• Fig. 3 is a schematic representation of one embodiment of the present invention.
• the heat load or charges are cooled by the evaporation of CO2 in one or more evaporators 2.
• the liquid CO 2 feeding the evaporator (s) is supplied by a cascade system 31 with vapor compression comparable to that described in the of FIG. 1, and by a cryogenic storage of CO 2 32.
• the two liquid CO 2 supply means are connected to the accumulation tank 3 of the low temperature circuit of the cascade system where the two CO 2 streams are mixed together. .
• the CO 2 resulting from the condensation of the low temperature circuit is expanded in the member 11 and accumulates in the tank 3.
• the CO 2 of the cryogenic storage is regulated in flow by the valve 21 and is expanded by the member 22 at the pressure of the tank 3.
• the circulation pump 4 is used to supply the evaporator (s) cooling the thermal load (s).
• the pump must be sized to circulate a flow equal to the sum of the CO2 flow rates provided by the cryogenic storage 32 and the low temperature compression circuit 7.
• the same is true for the evaporator or evaporators 2 which are dimensioned at the same time. help from the sum of CO 2 flows.
• the additional cooling power is supplied by the flow of CO2.
• CO 2 from cryogenic storage 32 The quantity of CO 2 injected into the tank 3 must be evacuated after evaporation of the liquid by means of an extraction circuit 33.
• the CO 2 flow rate provided by the storage 32 can provide from 0 to 100% of the cooling capacity related to the heat load or charges.
• the CO 2 coming from the storage will make it possible to supplement the cooling capacity of the compression system during peak production so as not to oversize the latter.
• the CO 2 of the cryogenic storage can ensure 100% of the refrigeration requirements, which prevents the production stoppage.
• the operating pressures and temperatures of the compression cascade system and the cryogenic storage are for example comparable to those already indicated with reference to FIGS. 1 and 2 above.
• FIG. 4 illustrates another example of implementation of the invention.
• the heat load or charges are cooled by one or two evaporators using CO 2 .
• the liquid CO 2 is provided, on the one hand, by the liquefaction of all or part of the CO 2 vapors from the evaporator (s) 2, condensation produced in the exchanger 41, and on the other hand by the CO 2 from cryogenic storage.
• the CO 2 flowing through the evaporator (s) and the condenser 41 is called a "coolant" fluid.
• a cold production system 40 (compression system using CO 2 or other refrigerants in cascade or not) allows the liquefaction of CO 2 from or evaporators 2.
• the liquefaction of CO 2 can take place in a exchanger separate storage tank 3 (as is the case of this Figure 4) or in this tank via an exchanger (as is the case in the context of Figure 6).
• CO 2 of the cryogenic storage is similar to that of FIG. 3.
• a reserve 3 allows the mixing of the two streams of CO 2 and two extraction lines 42 make it possible to extract a quantity of CO 2 equal to that coming from the cryogenic storage and to evacuate it to the outside ambient air.
• This extraction is carried out downstream of the evaporator 2 (on the line returning to the tank 3) and / or directly on the tank 3. This second case forces the condenser 41 not to completely condense the flow of CO 2 .
• the compression system producing the cooling effect to totally or partially cool the heat load is consisting of the compressor 56, a condenser 57, a high pressure tank 58, an expansion member 54 and one (or more) evaporators 50.
• the refrigerant is CO2.
• the cryogenic storage of CO2 51 is connected to the storage tank 58 via a pipe equipped with a flow control valve 52 and an expansion device 53.
• the CO 2 mixes with that of the system in the reservoir 58.
• the device operates in the modes previously described, the CO 2 of the cryogenic storage being able to provide from 0 to 100% of the refrigerating needs but preferably is used to supplement the cooling capacity of the compression system during peak production or shutdown of this system. latest.
• the CO 2 coming from the cryogenic storage is vaporized partially by the expansion in the member 53.
• the vapor is evacuated from the reservoir 58 by an extraction line 59.
• the liquid CO 2 accumulated in the reservoir 58 is expanded in the expansion 54 and is evaporated in the evaporator 50.
• an extraction (55) CO 2 vapor is installed to reject the CO 2 introduced by the cryogenic storage.
• the extractions 55 and 59 are adjusted so that the amount of CO 2 extracted is equal to that of the CO 2 introduced by the cryogenic storage.
• the condenser 57 is cooled by a compression system forming a cascade as explained for Figure 3 and not re-detailed here.

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• 2005
  • 2005-06-02 FR FR0551475A patent/FR2886719B1/fr not_active Expired - Fee Related
• 2006
  • 2006-05-18 WO PCT/FR2006/050460 patent/WO2006129034A2/fr active Application Filing
  • 2006-05-18 US US11/915,934 patent/US20090193817A1/en not_active Abandoned
  • 2006-05-18 EP EP06794443A patent/EP1902263A2/de not_active Withdrawn

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