EP0041005B1 - Method for mechanical energy production from heat using a mixture of fluids as the working fluid - Google Patents

Method for mechanical energy production from heat using a mixture of fluids as the working fluid Download PDF

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Publication number
EP0041005B1
EP0041005B1 EP81400755A EP81400755A EP0041005B1 EP 0041005 B1 EP0041005 B1 EP 0041005B1 EP 81400755 A EP81400755 A EP 81400755A EP 81400755 A EP81400755 A EP 81400755A EP 0041005 B1 EP0041005 B1 EP 0041005B1
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Prior art keywords
mixture
temperature
heat
process according
anyone
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German (de)
French (fr)
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EP0041005A1 (en
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Alexandre Rojey
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IFP Energies Nouvelles IFPEN
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IFP Energies Nouvelles IFPEN
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01KSTEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K25/00Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for
    • F01K25/06Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for using mixtures of different fluids

Definitions

  • Such a fluid vaporizes and condenses at a substantially constant temperature.
  • the fluid mixture of the above patent is a non-azeotropic mixture of trifluoroethanol and water.
  • the present invention is based on the observation that the temperature of the external fluids with which the exchanges take place changes, as a general rule, during the exchange.
  • the mixture is vaporized according to a temperature interval A by taking heat from an external fluid 1 which constitutes the heat source and the temperature of which changes according to a temperature interval A '. It is then relaxed by producing mechanical energy which can be used directly or transformed into electrical energy, then it is condensed according to a temperature interval B by yielding heat to an external fluid Il which constitutes the cooling fluid and whose the temperature changes according to a temperature interval B '.
  • the temperature intervals A and B must be as close as possible to the temperature intervals A 'and B', which corresponds to the best conditions of thermal reversibility.
  • the temperature interval A ' according to which the heat is supplied to the cycle being fixed, the composition of the mixture is chosen so as to obtain a vaporization interval A close to the temperature interval A'.
  • the temperature interval A In the case of a binary mixture, the temperature interval A generally changes as shown in the diagram shown in Figure 1.
  • the vaporization temperatures at the pressure considered are T l and T ll , the vaporization of the mixture begins at the bubble temperature of the liquid T LB and ends at the dew temperature of the vapor T VR .
  • the spraying interval is therefore equal to the difference between the temperatures T LB and T VR and can be adjusted by choosing the appropriate composition.
  • the condensation interval B is generally close to the vaporization interval A. In this case, it is advantageous to adjust the flow rate of the cooling fluid, water or air, used to carry out the condensation so that the interval of temperature B 'is close to the condensation interval B.
  • the mixture is then expanded in the vane motor M1 which drives the alternator AT1.
  • An electrical power of 9 kW is collected at the terminals of the alternator.
  • the mixture comes out of the M1 vane motor at a pressure of 1.6 bars. It is gradually condensed A in the exchanger E102 from where it is collected in the reserve tank B1. Cooling is ensured by water which enters through line 7 at 12 ° C and exits through line 8 at 32 ° C.
  • the liquid mixture is taken up, through line 6, by the pump P1 and recycled to the evaporator E101.
  • the use of a mixture of butane and hexane makes it possible, during the vaporization and condensation stages, to follow the temperature evolution of the external fluids, the mixture of fluids vaporizing according to an evolution increasing temperature parallel to the decreasing evolution of temperature of the external fluid 1 and condensing according to a decreasing evolution of temperature parallel to the increasing evolution of temperature of the external fluid II.
  • These changes in temperature necessitate operating the heat exchanges at the evaporator and at the condenser under conditions as close as possible to the counter-current.
  • a pure counter-current heat exchange mode represents the preferred solution, but for implementation reasons, it is also possible to mount exchange surfaces in a generally counter-current arrangement, each of the exchange surfaces forming part of said arrangement operating under conditions different from the counter current, for example following a heat exchange with cross currents or with a circulation of one of the fluids taking place in U-shaped tubes.
  • the mixtures (M) used can be mixtures of two, three (or more) constituents (separate chemical compounds).
  • the constituents of the mixture can be hydrocarbons, the molecule of which comprises a number of carbon atoms of for example between 3 and 8, such as propane, normal butane and isobutane, normal pentane and isopentane, normal hexane and isohexane, normal heptane and isoheptane, normal octane and isooctane as well as aromatic hydrocarbons such as benzene and toluene and cyclic hydrocarbons such as cyclopentane and cyclohexane.
  • the mixture used can be a mixture of halogenated hydrocarbons of the “Freon” type such as chlorodifluoromethane (R-22), dichlorodifluoromethane (R-12 ), chloropentafluoroethane (R-115), difluoroethane (R-152), trichlorofluoromethane (R-11), dichlorotetrafluoroethane (R-114), dichlorohexafluoropropane (R-216), dichlorofluoromethane (R-21), trichlorotrifluoroethane (R-113).
  • halogenated hydrocarbons of the “Freon” type such as chlorodifluoromethane (R-22), dichlorodifluoromethane (R-12 ), chloropentafluoroethane (R-115), difluoroethane (R-152), trichlorofluoromethane (R-11), dichlorotetrafluor
  • One of the constituents of the mixture can be an azeotrope such as the R-502 azeotrope of R-22 and R-115 (48.8 / 52.2% by weight), the R-500 azeotrope of R-12 and of R-31 (78.0 / 22.0% by weight), the azeotropic R-506 of R-31 and of R-114 (55.1 / 44.9% by weight).
  • an azeotrope such as the R-502 azeotrope of R-22 and R-115 (48.8 / 52.2% by weight), the R-500 azeotrope of R-12 and of R-31 (78.0 / 22.0% by weight), the azeotropic R-506 of R-31 and of R-114 (55.1 / 44.9% by weight).
  • mixtures comprising water and at least one second water-miscible constituent such as mixtures formed of water and ammonia, mixtures formed of water and an amine such as methylamine or ethylamine, mixtures formed of water and an alcohol such as methanol, mixtures formed of water and a ketone such as acetone.
  • the composition of the mixture is chosen so that the vaporization intervals A and condensation B are as close as possible to the temperature intervals A 'and B' according to which evolve external fluids.
  • the difference between the temperature intervals A and A ′ is less than 5 ° C.
  • the pump P11 makes it possible to send a fraction of the liquid mixture via the conduit 12 into the exchanger E103 in which it vaporizes according to a temperature interval A, by exchanging heat with an external fluid which enters through the conduit 13 and leaves by the conduit 14.
  • the mixture leaves vaporized from the exchanger E103 by the conduit 15 and it is sent to the engine stage M2.
  • the pump P10 sends the remaining fraction of the liquid mixture via the pipe 16 into the exchanger E104, in which it vaporizes according to a temperature interval A 2 by exchanging heat with the external fluid which arrives through the pipe 14 and exits through the conduit 17.
  • the mixture leaves vaporized from the exchanger E104 and the steam thus obtained is mixed with the steam coming from the expansion through the stage M2, then expanded at the same time as the steam coming from the stage M2 in the 'motor stage M3 from which it' emerges through conduit 19.
  • the intermediate pressure level is chosen correctly, that is to say the pressure at which the mixture vaporizes in the exchanger E104, the temperature intervals A and A 2 can be consecutive and it is thus possible to follow with the mixture a change in temperature parallel to a change in temperature of the external fluid which supplies heat to the cycle, corresponding to a temperature interval A 'approximately twice as wide as in the case of the operating diagram represented in the Figure 2.
  • the condensed mixture is only partially vaporized in the exchanger E106 by taking heat from the external fluid which arrives via line 20 and leaves via line 21.
  • the liquid and vapor fractions are separated in the separator flask S1.
  • the steam fraction is expanded in the T3 turbine.
  • the liquid phase is sent to the exchanger E107 in which it exchanges heat with the condensed mixture which is sent to the evaporator, then expanded through the expansion valve V1 and mixed with the expanded vapor phase leaving the turbine T3 .
  • the liquid vapor mixture thus obtained is condensed by yielding heat to an external cooling fluid, collected in the reserve tank B3 and recycled by the pump P3 to the evaporator.
  • the operating conditions of a device operating according to the arrangement shown diagrammatically in FIG. 4 are the subject of Example 2.
  • This mixture is sent through line 31 into the exchanger E107 from which it emerges through line 22 at a temperature of 55 ° C. It is then sent to the exchanger E106 in which it partially vaporizes by taking a thermal power of 1,585 kW from a flow of water which arrives via line 20 at a temperature of 90 ° C and exits through line 21 at a temperature of 65 ° C.
  • the liquid-vapor mixture leaves the exchanger E106 through line 23 at a temperature of 85 ° C. and at a pressure of 20 bars. It is collected in the separator tank S1 in which the liquid phase and the vapor phase are separated. The liquid phase contains 52% ammonia by weight. It is evacuated via line 25 and sent to the exchanger E107.
  • the vapor phase is sent via line 24 to the turbine T3 in which it is expanded to a pressure of 8 bars. On the shaft of the turbine T3, a power of 100 kW is collected by means of the electric brake FE1.
  • the expanded vapor is evacuated through the pipe 26.
  • the liquid phase which leaves through the pipe 27 of the exchanger E107 is expanded through the expansion valve V1, from where it comes out through the pipe 28. It is then mixed with the vapor phase arriving through line 26 and the liquid-vapor mixture is sent through line 29 into the air cooler AR1, in which it is fully condensed B and from which it leaves through line 30 at a temperature of 28 ° C.
  • the AR1 air condenser is made up of tubes provided with fins inside which the mixture circulates by condensing, these tubes being arranged in five layers placed transversely to the air circulation but mounted against the current , the mixture thus circulating generally against the current of the cooling air.
  • the condensed mixture is collected in the reserve tank B3 from where it is taken up by the feed pump P3.
  • the operating diagram shown in Figure 4, makes it possible to adapt to variable operating conditions.
  • the pressure levels in the evaporator and in the condenser are reduced, which makes it possible to reduce the capacity of the system, c is the power delivered on the shaft.
  • the operating conditions are generally chosen so that the pressure of the mixture in the evaporator is between 3 and 30 bars and so that the pressure of the mixture in the condenser is between 1 and 10 bars.
  • the temperatures constituting the temperature range A are all greater than 50 ° C and less than 350 ° C and the temperatures constituting the temperature range B are all greater than 20 ° C and less than 80 ° C.
  • the evaporator and the condenser can be, for example, tube and shell exchangers, double-tube exchangers or plate exchangers.
  • a fluid which is a gas for example if air is used as coolant for the condenser, it is generally advantageous to provide the exchange surfaces with fins placed on the side of the gas to improve heat exchange with this gas.
  • a machine can be for example a turbine with one wheel or with several wheels, radial or axial, a screw machine of the same type as the screw compressors but operating in expansion, a vane motor or a reciprocating piston engine.
  • the mechanical power delivered can be very variable and range, for example, from a few kW to several megawatts.
  • the mixture of fluids must not form an azeotrope under the conditions of vaporization. This means that at least two constituents of this mixture do not form an azeotrope between them; however, each of the constituents can individually be an azeotrope.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Engine Equipment That Uses Special Cycles (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)

Abstract

Mechanical power is generated by a process comprising (a) progressive vaporization of a mixture of fluids, (b) expansion of the resultant vapor, (c) condensation of the vapor and (d) recycling to step (a) of the liquid phase obtained in step (c). The heat exchanges are effected counter-currently, thus providing parallel evolutions of temperature. The condensation is effected in a temperature interval of from 7 DEG to 30 DEG C.

Description

La nécessité d'économiser l'énergie et d'utiliser de nouvelles sources d'énergie conduit à développer des procédés de production d'énergie mécanique, pouvant être utilisée directement ou transformée en énergie électrique, à partir de sources de chaleur à relativement bas niveau thermique, c'est-à-dire dans une gamme de température pouvant aller par exemple de 50 à 400 °C. De telles sources de chaleur peuvent être de nature diverse : rejets thermiques industriels, chaleur transmise par des capteurs solaires, eau géothermale, etc... A partir de telles sources de chaleur, il est possible de produire de l'énergie mécanique au moyen d'un cycle de Rankine utilisant un fluide de travail qui est vaporisé sous pression en prélevant de la chaleur sur la source de chaleur, détendu en produisant de l'énergie mécanique, par exemple dans une turbine, cette énergie mécanique pouvant être utilisée directement ou transformée en énergie électrique, et condensé au moyen d'un fluide de refroidissement, eau ou air.The need to save energy and use new energy sources leads to the development of processes for the production of mechanical energy, which can be used directly or transformed into electrical energy, from relatively low level heat sources thermal, that is to say in a temperature range which can range, for example, from 50 to 400 ° C. Such sources of heat can be of various nature: industrial thermal discharges, heat transmitted by solar collectors, geothermal water, etc ... From such sources of heat, it is possible to produce mechanical energy by means of '' a Rankine cycle using a working fluid which is vaporized under pressure by taking heat from the heat source, expanded by producing mechanical energy, for example in a turbine, this mechanical energy can be used directly or transformed into electrical energy, and condensed by means of a cooling fluid, water or air.

Pour améliorer le rendement du cycle et éviter d'opérer à très basse pression, il est avantageux de remplacer l'eau, qui est très généralement employée à plus haute température, par un fluide dont la température d'ébullition et la température critique sont beaucoup plus basses, tel que par exemple le butane ou l'ammoniac.To improve the efficiency of the cycle and avoid operating at very low pressure, it is advantageous to replace the water, which is very generally used at higher temperature, with a fluid whose boiling point and critical temperature are many lower, such as, for example, butane or ammonia.

Un tel fluide se vaporise et se condense à une température sensiblement constante.Such a fluid vaporizes and condenses at a substantially constant temperature.

On connaît déjà, du DE-A-2 215 868, un procédé de production d'énergie mécanique dans lequel

  • a) on vaporise progressivement un mélange de fluides comprenant au moins deux constituants ne formant pas d'azéotrope entre eux dans les conditions de vaporisation, en prélevant la chaleur de vaporisation au moins en partie sur un fluide extérieur I,
  • b) on détend la phase vapeur ainsi obtenue en produisant de l'énergie mécanique,
  • c) on condense progressivement la vapeur ainsi obtenue en cédant de la chaleur à au moins un fluide extérieur Il et
  • d) on recycle la phase liquide provenant de l'étape (c) à l'étape (a).
DE-A-2 215 868 already discloses a process for producing mechanical energy in which
  • a) progressively vaporizing a mixture of fluids comprising at least two constituents which do not form an azeotrope with one another under the vaporization conditions, by taking the heat of vaporization at least in part from an external fluid I,
  • b) the vapor phase thus obtained is relaxed by producing mechanical energy,
  • c) the vapor thus obtained is gradually condensed by yielding heat to at least one external fluid II and
  • d) the liquid phase from step (c) to step (a) is recycled.

Le mélange de fluides du brevet ci-dessus est un mélange non-azéotropique de trifluoréthanol et d'eau.The fluid mixture of the above patent is a non-azeotropic mixture of trifluoroethanol and water.

Le brevet britannique GB-A-2 016 607 considère que les mélanges non-azéotropiques de fluides sont insatisfaisants pour la mise en oeuvre de cycles de Rankine. Ce brevet propose donc l'emploi d'un mélange azéotropique de 2, 2, 3, 3-tétrafluoropropanol et d'eau.British patent GB-A-2,016,607 considers that non-azeotropic mixtures of fluids are unsatisfactory for the implementation of Rankine cycles. This patent therefore proposes the use of an azeotropic mixture of 2, 2, 3, 3-tetrafluoropropanol and water.

L'emploi, dans une pompe à chaleur, d'un échangeur de chaleur à contre-courant fonctionnant avec un fluide de travail anazéotropique est connu de FR-A-2337855.The use, in a heat pump, of a counter-current heat exchanger operating with an anzeotropic working fluid is known from FR-A-2337855.

La présente invention est basée sur l'observation selon laquelle la température des fluides extérieurs avec lesquels s'effectuent les échanges évolue, en règle générale, au cours de l'échange.The present invention is based on the observation that the temperature of the external fluids with which the exchanges take place changes, as a general rule, during the exchange.

Il a été découvert, et c'est là un des objets de la présente invention, qu'il est avantageux dans ce cas d'utiliser un mélange de fluides qui se vaporise et se condense progressivement en suivant l'évolution de température de chacun des fluides extérieurs avec lesquels s'effectuent les échanges.It has been discovered, and this is one of the objects of the present invention, that it is advantageous in this case to use a mixture of fluids which vaporizes and condenses progressively according to the temperature development of each of the external fluids with which exchanges take place.

Le mélange est vaporisé suivant un intervalle de température A en prélevant de la chaleur sur un fluide extérieur 1 qui constitue la source de chaleur et dont la température évolue suivant un intervalle de température A'. Il est alors détendu en produisant de l'énergie mécanique qui peut être utilisée directement ou transformée en énergie électrique, puis il est condensé suivant un intervalle de température B en cédant de la chaleur à un fluide extérieur Il qui constitue le fluide de refroidissement et dont la température évolue suivant un intervalle de température B'.The mixture is vaporized according to a temperature interval A by taking heat from an external fluid 1 which constitutes the heat source and the temperature of which changes according to a temperature interval A '. It is then relaxed by producing mechanical energy which can be used directly or transformed into electrical energy, then it is condensed according to a temperature interval B by yielding heat to an external fluid Il which constitutes the cooling fluid and whose the temperature changes according to a temperature interval B '.

Pour tirer pleinement parti du procédé selon l'invention, il est nécessaire toutefois d'observer certaines conditions.To take full advantage of the process according to the invention, it is however necessary to observe certain conditions.

Pour que le rendement obtenu soit maximum, les intervalles de température A et B doivent être aussi voisins que possible des intervalles de température A' et B', ce qui correspond aux meilleures conditions de réversibilité thermique. L'intervalle de température A' suivant lequel la chaleur est fournie au cycle étant fixé, la composition du mélange est choisie de manière à obtenir un intervalle de vaporisation A voisin de l'intervalle de température A'. Dans le cas d'un mélange binaire, l'intervalle de température A évolue généralement comme le montre le diagramme représenté sur la Figure 1. Pour une fraction molaire donnée XI du constituant 1 le plus volatil d'un mélange formé des constituants 1 et Il dont les températures de vaporisation à la pression considérée sont Tl et Tll, la vaporisation du mélange débute à la température de bulle du liquide TLB et se termine à la température de rosée de la vapeur TVR. L'intervalle de vaporisation est donc égal à l'écart entre les températures TLB et TVR et peut être ajusté en choisissant la composition appropriée.For the yield obtained to be maximum, the temperature intervals A and B must be as close as possible to the temperature intervals A 'and B', which corresponds to the best conditions of thermal reversibility. The temperature interval A 'according to which the heat is supplied to the cycle being fixed, the composition of the mixture is chosen so as to obtain a vaporization interval A close to the temperature interval A'. In the case of a binary mixture, the temperature interval A generally changes as shown in the diagram shown in Figure 1. For a given molar fraction X I of the most volatile component 1 of a mixture formed of components 1 and II, the vaporization temperatures at the pressure considered are T l and T ll , the vaporization of the mixture begins at the bubble temperature of the liquid T LB and ends at the dew temperature of the vapor T VR . The spraying interval is therefore equal to the difference between the temperatures T LB and T VR and can be adjusted by choosing the appropriate composition.

L'intervalle de condensation B est généralement voisin de l'intervalle de vaporisation A. Il est dans ce cas avantageux de régler le débit du fluide de refroidissement, eau ou air, employé pour effectuer la condensation de manière à ce que l'intervalle de température B' soit voisin de l'intervalle de condensation B.The condensation interval B is generally close to the vaporization interval A. In this case, it is advantageous to adjust the flow rate of the cooling fluid, water or air, used to carry out the condensation so that the interval of temperature B 'is close to the condensation interval B.

Ceci permet en outre, par rapport au fonctionnement avec un corps pur, de réduire le débit d'eau ou d'air de refroidissement et de diminuer la consommation d'énergie liée à la ventilation d'air de refroidissement ou au pompage d'eau de refroidissement. Toutefois, il est nécessaire d'éviter que l'intervalle de température B ne devienne trop important pour éviter une baisse du rendement. Pour cette raison, il importe de limiter l'intervalle de température B à une valeur de 30 °C. D'autre part, cet intervalle doit être d'au moins 7 °C pour que le gain de rendement qu'apporte l'utilisation d'un mélange soit notable. Par conséquent, pour se placer dans des conditions de rendement optimales et bénéficier des avantages qu'apporte l'utilisation d'un mélange, il importe que l'intervalle de température B soit compris entre 7 et 30 °C. Cette condition sera en général également valable pour l'intervalle de température A qui est généralement voisin de l'intervalle de température B, lorsque la vaporisation est opérée en une seule étape.This also makes it possible, compared to operation with a pure body, to reduce the flow of water or cooling air and to reduce the energy consumption linked to cooling air ventilation or to pumping water. cooling. However, it is necessary to avoid that the temperature interval B does not becomes too important to avoid a drop in yield. For this reason, it is important to limit the temperature interval B to a value of 30 ° C. On the other hand, this interval must be at least 7 ° C. so that the gain in yield brought about by the use of a mixture is significant. Consequently, in order to be placed in optimal yield conditions and to benefit from the advantages which the use of a mixture brings, it is important that the temperature range B is between 7 and 30 ° C. This condition will generally also be valid for the temperature interval A which is generally close to the temperature interval B, when the vaporization is carried out in a single step.

La réalisation du procédé peut être décrite en se référant à l'exemple 1.The implementation of the process can be described with reference to Example 1.

Exemple 1Example 1

L'exemple est illustré par la Figure 2. Par le conduit 1 arrive un débit de 5,67 m3/h d'eau à une température de 85 °C. Par le conduit 4, on fait parvenir 1 254 Kg/h d'un mélange de composition suivante (en fractions molaires) :

  • Butane normal : 0,8
  • Hexane normal : 0,2

Ce mélange arrive à 20 °C et commence à se vaporiser à 52 °C en échangeant de la chaleur à contre-courant avec l'eau qui arrive par le conduit 1 dans l'échangeur E101. Après échange, l'eau ressort de l'échangeur E101 par le conduit 2 à une température de 60 °C et le mélange ressort vaporisé de l'échangeur E101 par le conduit 3 à une température de 75 °C et à une pression de 4,1 bars.The example is illustrated in Figure 2. Via line 1 a flow of 5.67 m 3 / h of water arrives at a temperature of 85 ° C. Via line 4, 1254 kg / h of a mixture of the following composition are sent (in molar fractions):
  • Normal butane: 0.8
  • Normal hexane: 0.2

This mixture arrives at 20 ° C and begins to vaporize at 52 ° C by exchanging heat against the current with the water which arrives through line 1 in the exchanger E101. After exchange, the water leaves the exchanger E101 via the line 2 at a temperature of 60 ° C and the mixture leaves vaporized from the exchanger E101 through the line 3 at a temperature of 75 ° C and at a pressure of 4 , 1 bars.

Le mélange est alors détendu dans le moteur à palettes M1 qui entraîne l'alternateur AT1. On recueille aux bornes de l'alternateur une puissance électrique de 9 kW. Le mélange ressort du moteur à palettes M1 à une pression de 1,6 bars. Il est condensé progressivement A dans l'échangeur E102 d'où il est recueilli dans le bac de réserve B1. Le refroidissement est assuré par de l'eau qui entre par le conduit 7 à 12 °C et ressort par le conduit 8 à 32 °C.The mixture is then expanded in the vane motor M1 which drives the alternator AT1. An electrical power of 9 kW is collected at the terminals of the alternator. The mixture comes out of the M1 vane motor at a pressure of 1.6 bars. It is gradually condensed A in the exchanger E102 from where it is collected in the reserve tank B1. Cooling is ensured by water which enters through line 7 at 12 ° C and exits through line 8 at 32 ° C.

Le mélange liquide est repris, à travers le conduit 6, par la pompe P1 et recyclé à l'évaporateur E101.The liquid mixture is taken up, through line 6, by the pump P1 and recycled to the evaporator E101.

Dans cet exemple, l'utilisation d'un mélange de butane et d'hexane, permet, au cours des étapes de vaporisation et de condensation, de suivre l'évolution de température des fluides extérieurs, le mélange de fluides se vaporisant suivant une évolution croissante de température parallèle à l'évolution décroissante de température du fluide extérieur 1 et se condensant suivant une évolution décroissante de température parallèle à l'évolution croissante de température du fluide extérieur II. Ces évolutions de température nécessitent d'opérer les échanges de chaleur à l'évaporateur et au condenseur dans des conditions aussi proches que possible du contre-courant. Un mode d'échange de chaleur à contre-courant pur représente la solution préférée mais pour des raisons de réalisation, il est également possible de monter des surfaces d'échange selon un agencement globalement à contre-courant, chacune des surfaces d'échange faisant partie dudit agencement fonctionnant dans des conditions différentes du contre-courant, par exemple suivant un échange de chaleur à courants croisés ou encore avec une circulation d'un des fluides s'effectuant dans des tubes en U.In this example, the use of a mixture of butane and hexane makes it possible, during the vaporization and condensation stages, to follow the temperature evolution of the external fluids, the mixture of fluids vaporizing according to an evolution increasing temperature parallel to the decreasing evolution of temperature of the external fluid 1 and condensing according to a decreasing evolution of temperature parallel to the increasing evolution of temperature of the external fluid II. These changes in temperature necessitate operating the heat exchanges at the evaporator and at the condenser under conditions as close as possible to the counter-current. A pure counter-current heat exchange mode represents the preferred solution, but for implementation reasons, it is also possible to mount exchange surfaces in a generally counter-current arrangement, each of the exchange surfaces forming part of said arrangement operating under conditions different from the counter current, for example following a heat exchange with cross currents or with a circulation of one of the fluids taking place in U-shaped tubes.

Les mélanges (M) utilisés peuvent être des mélanges de deux, trois (ou davantage) constituants (composés chimiques distincts). Les constituants du mélange peuvent être des hydrocarbures dont la molécule comprend un nombre d'atomes de carbone compris par exemple entre 3 et 8, tels que le propane, le butane normal et l'isobutane, le pentane normal et l'isopentane, l'hexane normal et l'isohexane, l'heptane normal et l'isoheptane, l'octane normal et l'isooctane ainsi que des hydrocarbures aromatiques tels que le benzène et le toluène et des hydrocarbures cycliques tels que le cyclopentane et le cyclohexane. Lorsque l'on désire que le mélange ne soit pas inflammable ou ne soit que difficilement inflammable, le mélange utilisé peut être un mélange d'hydrocarbures halogénés du type « Fréon tels que le chlorodifluorométhane (R-22), le dichlorodifluorométhane (R-12), le chloro- pentafluoroéthane (R-115), le difluoroéthane (R-152), le trichlorofluorométhane (R-11), le dichlo- rotétrafluoroéthane (R-114), le dichlorohexafluo- ropropane (R-216), le dichlorofluorométhane (R-21), le trichlorotrifluoroéthane (R-113). L'un des constituants du mélange peut être un azéotrope tel que le R-502 azéotrope de R-22 et de R-115 (48,8/52,2 % en poids), le R-500 azéotrope de R-12 et de R-31 (78,0/22,0 % en poids), le R-506 azéotrope de R-31 et de R-114 (55,1/44,9 % en poids).The mixtures (M) used can be mixtures of two, three (or more) constituents (separate chemical compounds). The constituents of the mixture can be hydrocarbons, the molecule of which comprises a number of carbon atoms of for example between 3 and 8, such as propane, normal butane and isobutane, normal pentane and isopentane, normal hexane and isohexane, normal heptane and isoheptane, normal octane and isooctane as well as aromatic hydrocarbons such as benzene and toluene and cyclic hydrocarbons such as cyclopentane and cyclohexane. When it is desired that the mixture is not flammable or is only hardly flammable, the mixture used can be a mixture of halogenated hydrocarbons of the “Freon” type such as chlorodifluoromethane (R-22), dichlorodifluoromethane (R-12 ), chloropentafluoroethane (R-115), difluoroethane (R-152), trichlorofluoromethane (R-11), dichlorotetrafluoroethane (R-114), dichlorohexafluoropropane (R-216), dichlorofluoromethane (R-21), trichlorotrifluoroethane (R-113). One of the constituents of the mixture can be an azeotrope such as the R-502 azeotrope of R-22 and R-115 (48.8 / 52.2% by weight), the R-500 azeotrope of R-12 and of R-31 (78.0 / 22.0% by weight), the azeotropic R-506 of R-31 and of R-114 (55.1 / 44.9% by weight).

D'autres types de mélanges sont des mélanges comprenant de l'eau et au moins un second constituant miscible avec l'eau tels que les mélanges formés d'eau et d'ammoniac, les mélanges formés d'eau et d'une amine telle que la méthylamine ou l'éthylamine, les mélanges formés d'eau et d'un alcool tel que le méthanol, les mélanges formés d'eau et d'une cétone telle que l'acétone.Other types of mixtures are mixtures comprising water and at least one second water-miscible constituent such as mixtures formed of water and ammonia, mixtures formed of water and an amine such as methylamine or ethylamine, mixtures formed of water and an alcohol such as methanol, mixtures formed of water and a ketone such as acetone.

Lorsque le procédé fonctionne selon le schéma représenté sur la Figure 2, la composition du mélange est choisie de manière à ce que les intervalles de vaporisation A et de condensation B soient les plus voisins possible des intervalles de températures A' et B' selon lesquels évoluent les fluides extérieurs. Pour obtenir un gain maximum sur le rendement, il est préférable que l'écart entre les intervalles de température A et A' soit inférieur à 5 °C.When the process operates according to the diagram shown in Figure 2, the composition of the mixture is chosen so that the vaporization intervals A and condensation B are as close as possible to the temperature intervals A 'and B' according to which evolve external fluids. To obtain a maximum gain in yield, it is preferable that the difference between the temperature intervals A and A ′ is less than 5 ° C.

Il a été découvert également que dans le cas où un mélange est utilisé comme fluide de travail d'autres perfectionnements peuvent être envisagés lorsqu'en un point du circuit le mélange est scindé en deux fractions, qui sont remélangées en un autre point du circuit, l'une desdites fractions parcourant l'ensemble des différentes étapes du cycle et l'autre de ces fractions ne parcourant qu'une partie des étapes de ce cycle.It has also been discovered that in the case where a mixture is used as working fluid, other improvements can be envisaged. gés when at a point of the circuit the mixture is split into two fractions, which are remixed in another point of the circuit, one of said fractions crossing all the different stages of the cycle and the other of these fractions crossing only 'part of the stages of this cycle.

Si la chaleur récupérée à l'évaporateur est disponible dans un intervalle de température relativement large et que le mélange est choisi pour se vaporiser suivant un intervalle de température voisin, opérer selon le schéma de fonctionnement représenté sur la Figure 2 conduit à fonctionner avec un large intervalle de température B, ce qui ne correspond pas aux conditions les plus favorables au rendement. On peut dans ce cas opérer selon le schéma de fonctionnement représenté sur la Figure 3. Le mélange est condensé dans l'échangeur E105 en étant refroidi par un fluide extérieur qui entre par le conduit 9 et ressort par le conduit 10. Le mélange condensé ressort de l'échangeur E105 par le conduit 11 et il est envoyé dans le bac de réserve B2. La pompe P11 permet d'envoyer une fraction du mélange liquide par le conduit 12 dans l'échangeur E103 dans lequel il se vaporise suivant un intervalle de température A, en échangeant de la chaleur avec un fluide extérieur qui entre par le conduit 13 et ressort par le conduit 14. Le mélange ressort vaporisé de l'échangeur E103 par le conduit 15 et il est envoyé dans l'étage moteur M2. La pompe P10 envoie la fraction restante du mélange liquide par le conduit 16 dans l'échangeur E104, dans lequel il se vaporise suivant un intervalle de température A2 en échangeant de la chaleur avec le fluide extérieur qui arrive par le conduit 14 et ressort par le conduit 17. Le mélange ressort vaporisé de l'échangeur E104 et la vapeur ainsi obtenue est mélangée avec la vapeur provenant de la détente à travers l'étage M2, puis détendue en même temps que la vapeur provenant de l'étage M2 dans l'étage moteur M3 d'où elle' ressort par le conduit 19.If the heat recovered on the evaporator is available in a relatively wide temperature range and the mixture is chosen to vaporize according to a neighboring temperature range, operate according to the operating diagram shown in Figure 2 leads to operating with a wide temperature interval B, which does not correspond to the conditions most favorable to the yield. In this case, it is possible to operate according to the operating diagram represented in FIG. 3. The mixture is condensed in the exchanger E105 while being cooled by an external fluid which enters via the conduit 9 and leaves through the conduit 10. The condensed mixture emerges of the exchanger E105 via the conduit 11 and it is sent to the reserve tank B2. The pump P11 makes it possible to send a fraction of the liquid mixture via the conduit 12 into the exchanger E103 in which it vaporizes according to a temperature interval A, by exchanging heat with an external fluid which enters through the conduit 13 and leaves by the conduit 14. The mixture leaves vaporized from the exchanger E103 by the conduit 15 and it is sent to the engine stage M2. The pump P10 sends the remaining fraction of the liquid mixture via the pipe 16 into the exchanger E104, in which it vaporizes according to a temperature interval A 2 by exchanging heat with the external fluid which arrives through the pipe 14 and exits through the conduit 17. The mixture leaves vaporized from the exchanger E104 and the steam thus obtained is mixed with the steam coming from the expansion through the stage M2, then expanded at the same time as the steam coming from the stage M2 in the 'motor stage M3 from which it' emerges through conduit 19.

A condition de choisir convenablement le niveau de pression intermédiaire, c'est-à-dire la pression à laquelle le mélange se vaporise dans l'échangeur E104, les intervalles de température A, et A2 peuvent être consecutifs et il est ainsi possible de suivre avec le mélange une évolution de température parallèle à une évolution de température du fluide extérieur qui fournit de la chaleur au cycle, correspondant à un intervalle de température A' environ deux fois plus large que dans le cas du schéma de fonctionnement représenté sur la Figure 2.Provided that the intermediate pressure level is chosen correctly, that is to say the pressure at which the mixture vaporizes in the exchanger E104, the temperature intervals A and A 2 can be consecutive and it is thus possible to follow with the mixture a change in temperature parallel to a change in temperature of the external fluid which supplies heat to the cycle, corresponding to a temperature interval A 'approximately twice as wide as in the case of the operating diagram represented in the Figure 2.

Il a été également découvert que dans de nombreux cas il est particulièrement avantageux d'opérer selon l'agencement schématisé sur la figure 4. Le mélange condensé n'est vaporisé que partiellement dans l'échangeur E106 en prélevant de la chaleur sur le fluide extérieur qui arrive par le conduit 20 et repart par le conduit 21. A la sortie de l'échangeur E106 les fractions liquide et vapeur sont séparées dans le ballon séparateur S1. La fraction vapeur est détendue dans la turbine T3. La phase liquide est envoyée dans l'échangeur E107 dans lequel elle échange de la chaleur avec le mélange condensé qui est envoyé à l'évaporateur, puis détendue à travers la vanne de détente V1 et mélangée avec la phase vapeur détendue sortant de la turbine T3. Le mélange liquide vapeur ainsi obtenu est condensé en cédant de la chaleur à un fluide extérieur de refroidissement, recueilli dans le bac de réserve B3 et recyclé par la pompe P3 à l'évaporateur. Les conditions de fonctionnement d'un dispositif opérant selon l'agencement schématisé sur la Figure 4 font l'objet de l'exemple 2.It has also been discovered that in many cases it is particularly advantageous to operate according to the arrangement shown diagrammatically in FIG. 4. The condensed mixture is only partially vaporized in the exchanger E106 by taking heat from the external fluid which arrives via line 20 and leaves via line 21. On leaving the exchanger E106, the liquid and vapor fractions are separated in the separator flask S1. The steam fraction is expanded in the T3 turbine. The liquid phase is sent to the exchanger E107 in which it exchanges heat with the condensed mixture which is sent to the evaporator, then expanded through the expansion valve V1 and mixed with the expanded vapor phase leaving the turbine T3 . The liquid vapor mixture thus obtained is condensed by yielding heat to an external cooling fluid, collected in the reserve tank B3 and recycled by the pump P3 to the evaporator. The operating conditions of a device operating according to the arrangement shown diagrammatically in FIG. 4 are the subject of Example 2.

Exemple 2Example 2

L'exemple est illustré par la Figure 4. Par la pompe P3, on fait circuler un débit de 3 956 Kg/h d'un mélange d'eau et d'ammoniac de composition suivante (en fractions poids) :

Figure imgb0001
Figure imgb0002
The example is illustrated in Figure 4. By pump P3, a flow rate of 3,956 Kg / h is circulated of a mixture of water and ammonia of the following composition (in weight fractions):
Figure imgb0001
Figure imgb0002

Ce mélange est envoyé par le conduit 31 dans l'échangeur E107 d'où il ressort par le conduit 22 à la température de 55 °C. Il est alors envoyé dans l'échangeur E106 dans lequel il se vaporise partiellement en prélevant une puissance thermique de 1 585 kW sur un débit d'eau qui arrive par le conduit 20 à une température de 90 °C et ressort par le conduit 21 à une température de 65 °C. Le mélange liquide-vapeur ressort de l'échangeur E106 par le conduit 23 à la température de 85 °C et à la pression de 20 bars. Il est recueilli dans le bac séparateur S1 dans lequel la phase liquide et la phase vapeur sont séparées. La phase liquide contient 52 % d'ammoniac en poids. Elle est évacuée par le conduit 25 et envoyée à l'échangeur E107.This mixture is sent through line 31 into the exchanger E107 from which it emerges through line 22 at a temperature of 55 ° C. It is then sent to the exchanger E106 in which it partially vaporizes by taking a thermal power of 1,585 kW from a flow of water which arrives via line 20 at a temperature of 90 ° C and exits through line 21 at a temperature of 65 ° C. The liquid-vapor mixture leaves the exchanger E106 through line 23 at a temperature of 85 ° C. and at a pressure of 20 bars. It is collected in the separator tank S1 in which the liquid phase and the vapor phase are separated. The liquid phase contains 52% ammonia by weight. It is evacuated via line 25 and sent to the exchanger E107.

La phase vapeur est envoyée par la conduite 24 dans la turbine T3 dans laquelle elle est détendue jusqu'à une pression de 8 bars. Sur l'arbre de la turbine T3 on recueille au moyen du frein électrique FE1 une puissance de 100 kW. La vapeur détendue est évacuée par le conduit 26. La phase liquide qui ressort par le conduit 27 de l'échangeur E107 est détendue à travers la vanne de détente V1, d'où elle ressort par le conduit 28. Elle est alors mélangée avec la phase vapeur arrivant par le conduit 26 et le mélange liquide-vapeur est envoyé par le conduit 29 dans l'aéroré- frigérant AR1, dans lequel il est entièrement condensé B et d'où il ressort par le conduit 30 à la température de 28 °C.-L'aérocondenseur AR1 est formé de tubes munis d'ailettes à l'intérieur desquels le mélange circule en se condensant, ces tubes étant disposés en cinq nappes placées transversalement par rapport à la circulation d'air mais montées à contre-courant, le mélange circulant ainsi globalement à contre-courant de l'air de refroidissement. Le mélange condensé est recueilli dans le bac de réserve B3 d'où il est repris par la pompe d'alimentation P3.The vapor phase is sent via line 24 to the turbine T3 in which it is expanded to a pressure of 8 bars. On the shaft of the turbine T3, a power of 100 kW is collected by means of the electric brake FE1. The expanded vapor is evacuated through the pipe 26. The liquid phase which leaves through the pipe 27 of the exchanger E107 is expanded through the expansion valve V1, from where it comes out through the pipe 28. It is then mixed with the vapor phase arriving through line 26 and the liquid-vapor mixture is sent through line 29 into the air cooler AR1, in which it is fully condensed B and from which it leaves through line 30 at a temperature of 28 ° C. - The AR1 air condenser is made up of tubes provided with fins inside which the mixture circulates by condensing, these tubes being arranged in five layers placed transversely to the air circulation but mounted against the current , the mixture thus circulating generally against the current of the cooling air. The condensed mixture is collected in the reserve tank B3 from where it is taken up by the feed pump P3.

Le schéma de fonctionnement, représenté sur la Figure 4, permet de s'adapter à des conditions de fonctionnement variables. En particulier, en modifiant le débit acheminé par la pompe P3 à travers le conduit 31, il est possible de modifier les niveaux de pression à l'évaporateur et au condenseur. En particulier en augmentant le débit de la pompe P3, pour des températures de sortie à l'évaporateur et au condenseur fixées, on diminue les niveaux de pression à l'évaporateur et au condenseur, ce qui permet de réduire la capacité du système, c'est-à-dire la puissance délivrée sur l'arbre.The operating diagram, shown in Figure 4, makes it possible to adapt to variable operating conditions. In particular, by modifying the flow rate conveyed by the pump P3 through the conduit 31, it is possible to modify the pressure levels at the evaporator and at the condenser. In particular by increasing the flow rate of the pump P3, for fixed outlet temperatures to the evaporator and to the condenser, the pressure levels in the evaporator and in the condenser are reduced, which makes it possible to reduce the capacity of the system, c is the power delivered on the shaft.

De manière générale le mode de fonctionnement schématisé sur la figure 4 élargit considérablement les possibilités offertes par l'utilisation des mélanges dans les cycles moteurs.In general, the operating mode shown diagrammatically in FIG. 4 considerably widens the possibilities offered by the use of the mixtures in the engine cycles.

Il permet d'utiliser des mélanges de constituants dont les températures d'ébullition sont très différents, tels que l'eau et l'ammoniac, dans des applications où les intervalles de température dans l'évaporateur et le condenseur sont restreints, par exemple de l'ordre de 10 à 15°, puisque dans l'évaporateur on ne réalise qu'une vaporisation partielle, ce qui permet d'opérer avec un intervalle de température aussi réduit qu'on le souhaite.It makes it possible to use mixtures of constituents whose boiling temperatures are very different, such as water and ammonia, in applications where the temperature intervals in the evaporator and the condenser are restricted, for example of on the order of 10 to 15 °, since in the evaporator only partial vaporization is carried out, which makes it possible to operate with a temperature interval as reduced as desired.

D'autre part, comme celà a déjà été indiqué ci-dessus, il est possible dans un tel système d'ajuster les niveaux de pression en jouant sur la concentration de la solution qui circule. Il est possible ainsi de se placer dans les conditions optimales permettant de réaliser un débit volumique réduit et donc une machine de détente peu volumineuse sans mettre en jeu des pressions excessives qui conduiraient à des investissements trop importants.On the other hand, as already indicated above, it is possible in such a system to adjust the pressure levels by varying the concentration of the solution which circulates. It is thus possible to place oneself in the optimal conditions making it possible to achieve a reduced volume flow rate and therefore a low volume expansion machine without bringing into play excessive pressures which would lead to excessively large investments.

Quel que soit le schéma de fonctionnement, les conditions de fonctionnement sont choisies en général de manière à ce que la pression du mélange dans l'évaporateur soit comprise entre 3 et 30 bars et de manière à ce que la pression du mélange dans le condenseur soit comprise entre 1 et 10 bars. Les températures constituant l'intervalle de température A sont toutes supérieures à 50 °C et inférieures à 350 °C et les températures constituant l'intervalle de température B sont toutes supérieures à 20 °C et inférieures à 80 °C.Whatever the operating diagram, the operating conditions are generally chosen so that the pressure of the mixture in the evaporator is between 3 and 30 bars and so that the pressure of the mixture in the condenser is between 1 and 10 bars. The temperatures constituting the temperature range A are all greater than 50 ° C and less than 350 ° C and the temperatures constituting the temperature range B are all greater than 20 ° C and less than 80 ° C.

Les schémas de fonctionnement donnés à titre d'exemples ne sont pas limitatifs et en particulier tous les perfectionnements connus de l'homme de l'art dans le cas des cycles de Rankine utilisant un corps pur comme fluide de travail peuvent être envisagés dans le cas des mélanges. Par exemple lorsque le moteur dans lequel s'effectue la détente de la phase vapeur comporte plusieurs étages, il est possible de préchauffer le mélange liquide envoyé à l'évaporateur par un échange de chaleur avec une fraction vapeur prélevée entre deux étages du moteur, la condensation de cette fraction vapeur permettant de préchauffer le mélange liquide.The operating diagrams given by way of example are not limiting and in particular all the improvements known to those skilled in the art in the case of Rankine cycles using a pure body as working fluid can be envisaged in the case mixtures. For example, when the engine in which the expansion of the vapor phase takes place comprises several stages, it is possible to preheat the liquid mixture sent to the evaporator by heat exchange with a vapor fraction withdrawn between two stages of the engine, the condensation of this vapor fraction allowing the liquid mixture to preheat.

Il est également possible d'effectuer différentes variantes et combinaisons à partir des schémas de base qui ont été décrits. Par exemple, il est possible d'effectuer une vaporisation en deux ou plusieurs étapes à des niveaux de pression différents pour élargir l'intervalle de prélèvement de la chaleur, la vaporisation effectuée au cours de chacune desdites étapes de vaporisation n'étant que partielle et la phase liquide restant à l'issue desdites étapes de vaporisation étant recyclée à l'étape de condensation selon l'agencement qui a été décrit dans l'exemple 2 dans le cas d'une seule étape de vaporisation.It is also possible to make different variants and combinations from the basic diagrams which have been described. For example, it is possible to carry out a vaporization in two or more stages at different pressure levels in order to widen the heat removal interval, the vaporization carried out during each of said vaporization stages being only partial and the liquid phase remaining at the end of said vaporization stages being recycled to the condensation stage according to the arrangement which was described in Example 2 in the case of a single vaporization stage.

D'autre part, différents types d'équipements connus de l'homme de l'art peuvent être utilisés dans le procédé selon l'invention.On the other hand, different types of equipment known to those skilled in the art can be used in the method according to the invention.

L'évaporateur et le condenseur peuvent être par exemple des échangeurs à tubes et calandre, des échangeurs à double-tube ou des échangeurs à plaques. Lorsque l'échange de chaleur s'effectue avec un fluide qui est un gaz, par exemple si l'air est utilisé comme fluide de refroidissement au condenseur, il est généralement avantageux de munir les surfaces d'échange d'ailettes placées du côté du gaz pour améliorer l'échange thermique avec ce gaz.The evaporator and the condenser can be, for example, tube and shell exchangers, double-tube exchangers or plate exchangers. When the heat exchange takes place with a fluid which is a gas, for example if air is used as coolant for the condenser, it is generally advantageous to provide the exchange surfaces with fins placed on the side of the gas to improve heat exchange with this gas.

La détente de la phase vapeur générée dans l'évaporateur, qui permet de produire de l'énergie mécanique, peut s'effectuer dans toutes les machines connues pour cet échange : une telle machine peut être par exemple une turbine à une roue ou à plusieurs roues, radiale ou axiale, une machine à vis du même type que les compresseurs à vis mais fonctionnant en détente, un moteur à palettes ou un moteur alternatif à pistons.The expansion of the vapor phase generated in the evaporator, which makes it possible to produce mechanical energy, can be carried out in all the machines known for this exchange: such a machine can be for example a turbine with one wheel or with several wheels, radial or axial, a screw machine of the same type as the screw compressors but operating in expansion, a vane motor or a reciprocating piston engine.

La puissance mécanique délivrée peut être très variable et aller par exemple de quelques kW à plusieurs Mégawatts.The mechanical power delivered can be very variable and range, for example, from a few kW to several megawatts.

Dans les revendications qui suivent, il est indiqué que le mélange de fluides ne doit pas former d'azéotrope dans les conditions de la vaporisation. Ceci signifie qu'au moins deux constituants de ce mélange ne forment pas d'azéotrope entre eux ; cependant chacun des constituants peut à titre individuel être un azéotrope.In the claims which follow, it is indicated that the mixture of fluids must not form an azeotrope under the conditions of vaporization. This means that at least two constituents of this mixture do not form an azeotrope between them; however, each of the constituents can individually be an azeotrope.

Claims (12)

1. A process for producing mechanical power comprising
a) progressively vaporizing a fluid mixture (M) comprising at least two constituents which do not form an azeotrope in the vaporization conditions, by recovering vaporization heat at least partly from an external fluid I,
b) expanding the resultant vapor phase to produce mechanical power,
c) progressively condensing the resultant vapor phase while delivering heat to at least one external fluid II and
d) recycling to step (a) the liquid phase from step (c),

characterized in that the heat exchanges effected with the external fluids and II in the steps (a) and (c) respectively are operated counter-currently, the fluids mixture (M) being vaporized in step (a) according to an increasing temperature evolution (A) parallel to the decreasing temperature evolution (A') of the external fluid I and being condensed in step (c) according to a decreasing temperature evolution (B) parallel to the increasing temperature evolution (B') of the external fluid II, the width of the temperature interval B being at least 7 °C and at most 30 °C.
2. A process according to claim 1, wherein the fluids mixture is separated into two fractions at a point of the circuit and the resultant fractions are re-mixed at another point of the circuit, the first of these separated fractions being circulated through all the steps (a), (b) and (c) and the second of these fractions being not subjected to at least one of the steps through which circulates the first one of these fractions.
3. A process according to claim 1 or 2 wherein the difference between the temperature of the mixture working in interval A and the temperature of the fluid I working in interval A' is at each time lower than 5 °C.
4. A process according to anyone of claims 1 to 3 wherein the mixture (M) is vaporized in at least two steps effected at distinct pressure levels, a first fraction of the mixture being vaporized at the highest pressure level by receiving heat in a first temperature interval, the resultant vapor phase being supplied to the inlet of the working machine where the expanding takes place, said working machine comprising a number of stages (M2. M3) at least equal to the number of vaporization stages, the remaining fraction being vaporized in at least one step effected at a pressure level lower than the pressure level of the first step by recovering heat in a temperature interval which is at least in part below the first temperature interval, the resultant vapor fraction(s) being fed to the sucessive stages (M3) of the working machine where the expansion takes place, at points corresponding to the pressure levels of the vapor, the vapor mixture obtained after expansion being condensed and the liquid phase obtained after condensation being recycled to the vaporization steps.
5. A process according to anyone of claims 1 to 4 wherein the mixture (M) is partially vaporized in the evaporator E 106 by receiving heat from an external fluid, the resultant vapor phase and liquid phase being separated, the vapor phase being expanded with mechanical power production, the liquid phase being supplied to an exchanger E 107 where it exchanges heat with the condensed mixture (M) which is fed to the evaporator, the liquid phase being thereafter expanded and admixed with the expanded vapor phase, the resultant liquid-vapor mixture being condensed with heat release to an external fluid, the resultant condensed mixture (M) being recycled to the evaporator.
6. A process according to anyone of claims 1 to 5 wherein the mixture is a hydrocarbons mixture whose number of carbon atoms is from 3 to 8.
7. A process according to anyone of claims 1 to 5 wherein the mixture is a mixture of halogenated hydrocarbons.
8. A process according to anyone of claims 1 to 5 wherein the mixture is a mixture of water with at least one constituent miscible with water, selected from alcohols, ketones and amines.
9. A process according to anyone of claims 1 to 5 wherein the mixture is a mixture of water with ammonia.
10. A process according to anyone of claims 1 to 9 wherein the temperature interval A is comprised in the temperature range from 50 to 350 °C and the temperature interval B is comprised in the temperature range from 20 to 80 °C.
11. A process according to anyone of claims 1 to 10 wherein the pressure of the mixture in the evaporator is selected between 3 and 30 bars and the pressure of the mixture in the condenser is selected between 1 and 10 bars.
12. A process according to anyone of claims 1 to 11 wherein the mechanical power produced by expanding the vapor phase mixture is converted to electric power.
EP81400755A 1980-05-23 1981-05-12 Method for mechanical energy production from heat using a mixture of fluids as the working fluid Expired EP0041005B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT81400755T ATE14778T1 (en) 1980-05-23 1981-05-12 PROCESS FOR MECHANICAL ENERGY GENERATION FROM HEAT USING MULTI-SUBSTANCE MIXTURES AS WORK EQUIPMENT.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8011649A FR2483009A1 (en) 1980-05-23 1980-05-23 PROCESS FOR PRODUCING MECHANICAL ENERGY FROM HEAT USING A MIXTURE OF FLUIDS AS A WORKING AGENT
FR8011649 1980-05-23

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EP0041005A1 EP0041005A1 (en) 1981-12-02
EP0041005B1 true EP0041005B1 (en) 1985-08-07

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US (1) US4422297A (en)
EP (1) EP0041005B1 (en)
JP (1) JPS5728819A (en)
AT (1) ATE14778T1 (en)
DE (1) DE3171684D1 (en)
FR (1) FR2483009A1 (en)

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Also Published As

Publication number Publication date
US4422297A (en) 1983-12-27
FR2483009B1 (en) 1982-07-23
FR2483009A1 (en) 1981-11-27
DE3171684D1 (en) 1985-09-12
ATE14778T1 (en) 1985-08-15
JPS5728819A (en) 1982-02-16
EP0041005A1 (en) 1981-12-02

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