FR3045726A1 - DEVICES AND METHOD FOR EXTRACTING AND VALORIZING THE ENERGY OF RELAXATION OF A GAS UNDER HEAT PRESSURE - Google Patents

Abstract

The device (10) for extracting and recovering the expansion energy of an unheated pressurized gas comprises: - a rotating machine type gas expansion valve (110) comprising a shaft (111) free to rotate to perform a quasi-adiabatic expansion and thereby to produce mechanical energy on the rotating shaft, - a heat exchanger / heat exchanger (115) having an inlet (125) for a vaporized organic fluid, the organic fluid having a boiling point below 40 ° C at ambient pressure; a circuit (140) closed for the organic fluid, called "ORC machine" (for Organic Rankine Cycle), connecting: - the output of the heat exchanger to a pump (155), - the pump to a heat exchanger ( 145) evaporator, the evaporator exchanger to a vaporized organic fluid expander (170) and the organic fluid expander to the condenser / heater heat exchanger, of rotating machine type and performing a quasi-adiabatic relaxation of the organic fluid. and producing mechanical energy on a rotating shaft and - an outlet connection (145) for the expanded gas downstream of the condenser / heater heat exchanger.

Description

TECHNICAL FIELD OF THE INVENTION

The present invention relates to devices and a method for extracting and developing the expansion energy of an unheated pressure gas. It applies in particular to gas expansion stations, including natural gas, CO2 or hydrogen, located between high-pressure networks, and networks, low pressure.

STATE OF THE ART

To relax gas from a high pressure network (for example in the case of a transport network) to a low pressure network (for example in the case of a distribution network), the person skilled in the art now has many solutions.

In some current systems, a rolling valve is implemented. This device creates a high pressure drop, relaxing in a quasi-isothermal manner the gas of a high pressure, for example 22 or 63 bar, at a low pressure, for example 2 or 11 bar, conducive to the distribution to users of gas. The expansion being quasi-isothermal, the expanded gas is output at a temperature approximately equal to the initial temperature.

In this configuration, the exergy of the high pressure state is destroyed and there is no recovery of mechanical energy possible.

In other current systems, a regulator allowing a quasi-adiabatic relaxation is implemented. The use of a regulator, sometimes called an expander, produces mechanical energy in the form of a rotating shaft. The pressure energy is recovered during the quasi-adiabatic expansion which causes a strong cooling of the gas. In the context of a natural gas expansion at 22 bar at a pressure of 2 bar on a conventional machine-type expansion valve with an isentropic efficiency of 85%, the temperature obtained at the end of expansion is of the order of - 100 ° C for a gas initially at 15 ° C. The mechanical energy recovered on the regulator can be used to rotate a shaft, to operate an electric generator and thus produce electricity.

There are various quasi-isentropic expansion devices generating mechanical energy, including volumetric type expansion devices (screw expander, piston) or turbomachine type expansion valves (axial or radial turbine). These devices are rotating machines.

In the context of a quasi-adiabatic relaxation, the cooling obtained during the relaxation can create important problem of formation of ice crystals in the networks and on the pipes. The gas is therefore generally heated subsequently by an air / gas exchanger, for example, in order to bring the expanded gas to a temperature above 0 ° C. In this configuration, electrical energy is produced but the generated cold is evacuated and exergy is also destroyed. As an example of a regulator performing a quasi-adiabatic expansion, there may be mentioned the French patent FR 2438158 which teaches a specific turbine-generator configuration and the management of seals.

It is noted that the management of the cold generated by the expansion of the gas is a major concern. For example, US Patent 8375717 considers the preheating of the gas by an electrical system to maintain the temperature following the expansion (also called expansion) of the gas and prevent the formation of ice crystals. In this configuration, much of the electricity generated is not valued beyond the process.

In the case of quasi-adiabatic expansion valve, the state of the art also describes uses of cold produced for industrial purposes for example, and for the purpose of heating the gas thus relaxed.

It is noted that, from a theoretical point of view, an infinite succession of adiabatic expansion with partial reheating has as its limit an isothermal expansion.

Moreover, with regard to Rankine's organic-cycle machine technology that makes it possible to produce electricity from a difference in temperature between two heat sources, it is extensively explained in the literature for the production of electricity. between a hot source (recovered from a boiler-type process, furnace, geothermal water, or hot fluids from an exothermic process) and a cold source (usually water cooled by ambient air , ambient air or thermal fluid used for low temperature heating or process applications).

Thus, for example, US patent application US2013160486 discloses an invention for producing electricity in combination with a LNG regasification unit (for "Liquified Natural Gas", translated as liquefied natural gas). This paper refers to the use of Organic Rankine Cycle (ORC) technology for the production of energy from the evaporation of LNG ("Design of Rankine Cycles for power generation from evaporating LNG", Maertens, J. International Journal of Refrigeration, 1986, Vol 9, May).

The systems described above are intended to produce electricity using a cold source from an external process such as regasification of Liquefied Natural Gas above.

Thus, we note that: - the existing systems to extract and valorize the energy of expansion of a gas under unheated pressure or of a cold source thus created do not maximize the whole exergy (that is, that is to say the energy in its best quality, in mechanical or electrical form) available initially and that - the systems which make it possible to recover the energy of pressure in mechanical or electrical energy have the disadvantage of the formation of ice crystals, with a possible deterioration of transport infrastructure and distribution of expanded gas. If there are systems for producing electricity from a cold source, the origin thereof is external to the device used in the systems described.

OBJECT OF THE INVENTION

The present invention aims to remedy all or part of these disadvantages. For this purpose, according to a first aspect, the present invention is directed to a device for extracting and recovering the expansion energy of an unheated pressurized gas, which comprises: a rotary machine type gas expander comprising a rotational free shaft configured to effect a quasi-adiabatic expansion and thereby to produce mechanical energy on the rotating shaft, - a condenser / heater heat exchanger comprising: - an inlet for the expanded gas; an inlet for an organic fluid in vapor form, the organic fluid having a boiling point below 40 ° C. at ambient pressure; an outlet for warmed expanded gas and an outlet for cooled and condensed organic fluid; a closed circuit for the organic fluid, called "ORC" machine (for Organic Rankine Cycle), connecting: output of the heat exchanger to a pump, - the pump to an evaporator exchanger, - the evaporator exchanger to a vaporized organic fluid expander and - the organic fluid expander to the condenser / reheater heat exchanger, the expander of organic fluid being a rotating machine and performing a quasi-adiabatic expansion of the organic fluid, and producing mechanical energy on a rotating shaft and - an outlet connection for the expanded gas downstream of the condenser / heat exchanger heater.

Thanks to these provisions, the cold source of the ORC machine is formed by the expanded gas and the hot source by the ambient air, or an external thermal source. This device thus makes it possible: on the one hand to allow the heating of the expanded gas and to prevent the formation of ice crystals in the expanded gas and, on the other hand, to optimize the production of electric current at the same time during the expansion gas in the expander and via the valuation of the cold generated in an organic fluid circuit internal to the device.

If the scientific and technical literature amply describes the case of systems with expansion of heated pressurized gas, possibly in combined cycle with an additional means of producing energy from the residual heat still available at the end of the first expansion, the present invention does not relate to this topic, because it deals with the relaxation of unheated pressure gas and the recovery of the cold generated during the expansion of the gas (as a cold source of the thermodynamic machine), and not heat residual (as hot source of the thermodynamic machine).

In embodiments, at least one expander is a turbomachine, a shaft of each turbomachine being connected to a generator configured to convert the mechanical energy produced by said expander into electricity.

In embodiments, the shafts of each expander are coupled to a common shaft.

These embodiments make it possible to optimize the mechanical architecture of the regulators.

In embodiments, the flows of gas and / or organic fluid vaporized in the device are partially two-phase gas-liquid, with a vapor head greater than 80% by weight for the gas portion.

These embodiments make it possible to optimize the operation of the thermodynamic cycles.

In embodiments, each expander has an exhaust, each exhaust being connected to a common exchanger.

These embodiments make it possible to optimize the energy performance of the device by reducing the pressure losses on the gas side and to improve the heating of the expanded gas, by reducing the formation of ice.

In embodiments, the device which is the subject of the present invention comprises, downstream of the heated expanded gas outlet of the condenser / heater exchanger, a reheated heat exchanger of the heated gas.

These embodiments make it possible to bring the expanded gas to the distribution specifications, in the case of partial heating only of the expanded gas flow.

In embodiments, the organic fluid is a zeotropic mixture.

These embodiments make it possible to optimize the production of mechanical energy and the heating of the expanded gas

According to a second aspect, the present invention aims at a device for enhancing and optimizing the expansion energy of an unheated pressure gas, which comprises: a first rotary machine type gas expander comprising a free shaft; in rotation configured to perform a quasi-adiabatic expansion and thereby produce mechanical energy on the rotating shaft, - a first heat exchanger condenser / heater comprising: - an inlet for the expanded gas from the first expander; an inlet for a vaporized organic fluid, the organic fluid having a boiling point of less than 40 ° C. at ambient pressure; an outlet for warmed expanded gas and an outlet for cooled and condensed organic fluid; a second expander, of rotating machine type, connected to the expanded gas outlet of the first heat exchanger, comprising a free rotating shaft configured to produce a quasi-adiabatic expansion and thus to produce mechanical energy on the shaft in rotation, - a second heat exchanger condenser / heater including: - an inlet for the expanded gas from the second expander; an inlet for the organic fluid; an outlet for warmed expanded gas and an outlet for cooled and condensed organic fluid; a closed circuit for the organic fluid, called "ORC" machine (for Organic Rankine Cycle), connecting: organic fluid outlet from each heat exchanger to a pump, - each pump to an evaporator exchanger, - the evaporator exchanger to a vaporized organic fluid expander and - the organic fluid expander to the organic fluid inlet of each exchanger heat exchanger of the condenser / heater type, the expander being a rotating machine and performing a quasi-adiabatic expansion of the organic fluid, and producing mechanical energy on a rotating shaft and - an outlet connection for the expanded gas downstream of the second heat exchanger condenser / heater.

The aims, advantages and particular characteristics of the device object of the second aspect of the present invention being similar to those of the device object of the first aspect of the present invention, they are not recalled here.

In addition to these advantages, this second aspect optimizes the heating of the expanded gas.

According to a third aspect, the present invention aims at a method of upgrading and optimizing the expansion energy of an unheated pressure gas, which comprises: a step of quasi-adiabatic expansion and thus producing energy mechanical on a rotating shaft of the gas entered into a pressure reducer, the expander comprising the shaft in rotation, - a heat exchange step comprising: - on the one hand: - an inlet step for the expanded gas; a step of reheating the gas expanded by a vaporized organic fluid and an outlet step of the heated expanded gas and secondly: an inlet step for the vaporized organic fluid, the organic fluid having a temperature of boiling below 40 ° C at ambient pressure; a step of condensation and cooling of the organic fluid during heating of the expanded gas and an output stage for cooled and condensed organic fluid; a closed-circuit circulation step for the organic fluid comprising: a step of moving the organic fluid leaving the heat exchange stage to a pump; a step of displacement of the organic fluid from the pump to an evaporator exchanger; a step of exchange by evaporation of the organic fluid; a step of displacement of the organic fluid from the evaporator exchanger to a vaporized organic fluid expander; a step of relaxing the vaporized organic fluid; a step of displacement of the organic fluid from the expander to serve as an organic fluid during the inlet stage for the fluid of the heat exchange stage and an outlet step for the expanded gas downstream of the heat exchanger stage.

Since the aims, advantages and particular characteristics of the method which are the subject of the present invention being similar to those of the device which is the subject of the present invention, they are not recalled here.

BRIEF DESCRIPTION OF THE FIGURES Other advantages, aims and particular characteristics of the invention will become apparent from the following nonlimiting description of at least one particular embodiment of the device and method that are the subject of the present invention, with reference to the accompanying drawings. , in which: - Figure 1 shows schematically a first particular embodiment of the device object of the present invention, - Figure 2 shows schematically a second particular embodiment of the device object of the present invention, - the FIG. 3 represents, schematically, a first particular temperature-entropy diagram of the thermodynamic cycle implemented by the device which is the subject of the present invention; FIG. 4 schematically represents a second particular temperature-entropy diagram of the thermodynamic cycle set in FIG. implemented by the device which is the subject of the present invention, 5 represents, schematically, a third particular temperature-entropy diagram of the thermodynamic cycle implemented by the device which is the subject of the present invention; FIG. 6 schematically represents a third particular embodiment of the device which is the subject of the present invention, FIG. 7 schematically represents a fourth particular embodiment of the device that is the subject of the present invention and FIG. 8 represents, schematically and in the form of a logic diagram, a particular sequence of steps of the method that is the subject of the present invention. .

DESCRIPTION OF EXAMPLES OF EMBODIMENT OF THE INVENTION

This description is given in a nonlimiting manner, each feature of an embodiment being able to be combined with any other feature of any other embodiment in an advantageous manner.

It is already noted that the figures are not to scale.

The term "organic fluid" refers to any working fluid derived from carbon chemistry, and in particular to chemical compounds that are predominantly composed of alkanes, fluorinated alkanes, ethers and / or fluorinated ethers. This organic fluid is composed, for example, of ethane or ethylene. In variants, this organic fluid is a zeotropic mixture. Such a zeotropic mixture allows evaporation at a non-constant temperature and pressure, in order to better heat the pressurized gas and / or to better valorize the cold source generated during expansion of the gas under relaxed pressure.

FIG. 1, which is not to scale, shows a schematic view of an embodiment of the device 10 which is the subject of the present invention. This device 10 for expanding a pressurized gas comprises: - a gas-type regulator 110 of the rotating type, comprising a shaft 111 free in rotation configured to perform a quasi-adiabatic expansion and thereby produce mechanical energy on the rotating shaft, - preferably, a valve 105 for adjusting the gas flow entering the expander 110, - a heat exchanger 115 condenser / heater comprising: - an inlet 120 for the expanded gas; an inlet 125 for a vaporized organic fluid, the organic fluid having a boiling point of less than 40 ° C. at ambient pressure; an outlet 130 for heated expanded gas and an outlet 135 for cooled and condensed organic fluid; a closed circuit 140 for the organic fluid, called "ORC machine" for Organic Rankine Cycle, translated by Organic Rankine Cycle, connecting: the outlet of the heat exchanger to a pump 155, the pump to an evaporator exchanger, the evaporator exchanger to a vaporized organic fluid expander 170 and the organic fluid expander to the condenser heat exchanger heater, the expander being a rotating machine and performing a quasi-adiabatic expansion of the organic fluid, and producing mechanical energy on a rotating shaft and - an outlet connection 145 for the expanded gas downstream of the heat exchanger condenser / heater.

The device 10 may be positioned on a branch of a pipe 190 of gas under pressure.

The expander 110 is, for example, a turbomachine turbine type having a shaft 111 actuating a shaft 185 set in motion during the expansion of the gas in the enclosure of the holder 110.

The gas entering the expander 110 is expanded to a low temperature and then directed to the heat exchanger 115 to be heated. The exchanger 115 is, for example, an exchanger of the organic fluid condenser type. Within this exchanger 115, the organic fluid transfers the latent heat of condensation to the gas entering the exchanger 115. The inlet 120 for the expanded gas is, for example, a pipe connecting the expander 110 to the exchanger 115. This inlet 120 is connected to a first opening of the exchanger 115. The inlet 125 for the organic fluid is, for example, a pipe connecting the expander 170 to the exchanger 115. This inlet 125 is connected to a second opening of the exchanger 115.

The outlet 130 for the expanded and heated gas is, for example, a pipe connecting the heat exchanger 115 to the outlet connection 145 or to a heat exchanger 144 such as that described below. This output 130 is connected to a third opening of the exchanger 115.

The outlet 150 for the organic fluid is, for example, a pipe connecting the exchanger 115 to the pump 155. This outlet 150 is connected to a fourth opening of the exchanger 115.

Thus, as understood, the exchanger 115 comprises: - a expanded gas circuit arriving cold by a pipe 120 and spring heated by a pipe 130 and - a low pressure organic fluid vapor circuit arriving hot by a pipe 125 and springing condensed and cooled by piping 150.

The closed circuit 140 for the organic fluid is formed by: - the pipe 150 connecting the heat exchanger 115 to the pump 155, - a pipe 160 connecting the pump 155 to the exchanger 145 evaporator, - a pipe 185 connecting the exchanger 145 evaporator expander 170 and - the pipe 125 connecting the expander 170 to the exchanger 115.

The expanded and heated gas from exchanger 115 is preferentially heated in a heat exchanger 144 and re-injected into a gas pipe 195 connected to a distribution network, this gas line 195 being connected to the output connection 145.

In preferred embodiments, the flows of gas and / or fluid in the device 10 are diphasic gas-liquid, with a vapor content greater than 80% by weight for the gas portion. The exchanger 145 evaporator is, for example, an exchanger with ambient air or an exchanger with another fluid, such hot water or hot oil from an external process such, for example, a system heating boiler type or solar boiler, or by geothermal or by valorization of industrial thermal discharges. In this case, the organic fluids used for the cycle allow the best value of this temperature. By way of illustration, if there are heat sources in the form, for example, of hot water at a temperature of several tens of degrees to be cooled, the use of a fluid such as propane, the temperature of which is boiling at 1 bar is less than 40 ° C but higher than that of ethane, or a mixture of zeotropic fluid using propane improves the electrical efficiency of the assembly.

The pump 155 allows the circulation of the organic fluid in liquid form having a low pressure at the outlet of the heat exchanger 115 and the regulation of the operation of the whole of the organic Rankine cycle machine.

The expander 170 is, for example, a turbomachine provided with a shaft 171 actuating a shaft 185. This expander 170 is, in variants, volumetric type such, for example, a screw expander or a piston expander.

The choice of the type of regulator 170 depends on technical parameters such as the nature, the flow rate and the pressure drop achieved by the expanded gas, as well as the speed of rotation of the desired assembly. The assembly formed by the exchanger 115, the expander 170, the exchanger 145 evaporator and the pump 155 is an organic cycle Rankine machine. This machine corresponds to the different devices positioned along the closed circuit 140.

In preferred embodiments, such as that illustrated in FIG. 1, at least one expander, 170 and / or 110, is a turbomachine, a shaft of each turbomachine being connected to a generator 180 configured to convert the mechanical energy produced by said expander in electricity. The rotation of each shaft can cause the rotation of a single common shaft 185 coupled to the shafts of each expander, 110 and 170. This shaft 185 is coupled to a generator 180 configured to produce electricity through the rotation of each shaft. . The generator 180 is connected in direct coupling, or via the implementation of a gearbox.

In variants, the device 10 comprises a coupling between the gas expander 110 and the expander 170 of heated and vaporized organic fluid. This coupling is achieved by means of: - a common shaft on which at one end is fixed a wheel or several gas expansion turbine wheels and at the other end a wheel or several fluid-free turbine impeller roads, this shaft being placed on two bearings and - a generator disposed on the shaft between the two wheels and between the two bearings.

In embodiments, thermal energy dissipated by the bearings, lubrication systems of the gas expanders and the electric generator, is used to heat the gas under relaxed pressure, this gas has become cold during expansion.

In preferred embodiments, such as that illustrated in Figure 1, the device 10 comprises, downstream of the outlet 130 for heated expanded gas, a heat exchanger 144 heating the expanded heated gas. This heat exchanger 144 is configured to bring the gas to a temperature close to the temperature of the inlet gas 100 of the device 10. FIG. 2 diagrammatically shows a particular embodiment of the device 20 of the present invention. This device 20 for expansion of a pressurized gas comprises: - a first expander 211 of rotating machine type gas, comprising a free rotating shaft configured to perform a quasi-adiabatic expansion and thereby produce mechanical energy on the shaft in rotation, - preferably, a valve 205 for adjusting the gas flow entering the first expander 211, - a first heat exchanger 221 condenser / heater comprising: - an inlet 223 for the expanded gas from the first expander; an inlet 224 for an organic fluid, the organic fluid having a boiling point of less than 40 ° C. at ambient pressure; an outlet 225 for heated expanded gas and an outlet 226 for cooled and condensed organic fluid; a second expander 212 of rotating machine type connected to the expanded gas outlet of the first heat exchanger, comprising a free shaft in rotation; configured to perform a quasi-adiabatic expansion and thereby produce mechanical energy on the rotating shaft, - a second heat exchanger 222 condenser / heater comprising: - an inlet 227 for the expanded gas from the second expander; an inlet 228 for the organic fluid; an outlet 229 for heated expanded gas and an outlet 230 for cooled and condensed organic fluid; a closed circuit 240 for the organic fluid, called "ORC machine" for Organic Rankine Cycle, translated by Organic Rankine Cycle, connecting: the organic fluid outlet of each heat exchanger to a pump 261,262, each pump to an evaporator exchanger 270, the evaporator exchanger to a vaporized organic fluid expander 271 and the vaporized organic fluid expander to the inlet for organic fluid of each condenser / heater heat exchanger; the expander being of rotating machine type and performing a quasi-adiabatic expansion of the organic fluid, and producing mechanical energy on a rotating shaft and - an outlet connection 255 for the expanded gas downstream of the second condenser / heat exchanger heater, - preferably, a heat exchanger 250 gas heater from the outlet 229 of the second exchanger 22, - preferably, a generator 281 connected to the expander, 211 and / or 212, correspondingly to the generatrix 180 described with reference to FIG. 1 and - preferably, a generator 282 connected to the expander 271.In this improved gas expansion device 20, the expansion of the unheated pressure gas is carried out in two stages, with intermediate reheating.

In this variant of the device 10, the device 20 has several intermediate stages of quasi-adiabatic expansion unheated pressure gas. As can be understood, the number of stages can be greater than two by adding an additional expander and an additional condenser / heater heat exchanger connected or not to the closed circuit 240 in a manner similar to the second exchanger 222.

In embodiments, the regulators 211 and 212, unheated pressure gas are mechanically coupled to the same shaft and the same generator 281, possibly by the implementation of a gearbox.

In embodiments, at least one of the regulators, 211 and / or 212, of unheated pressurized gas are turbine engines of the radial or axial turbine type.

In variants, at least one of the holders, 211 and / or 212, of unheated pressure gas is a volumetric expander, such as a screw or piston expander.

In embodiments, the organic fluid expander 271 is mechanically coupled with at least one expander, 211 and / or 212, on the same shaft and the generatrices 281 and 282 are merged.

In variants, the closed circuit 240 of organic fluid comprises several organic fluid expander such as the expander 271, each said expander being connected to an exchanger, 221 or 222.

FIG. 3 shows a temperature-entropy diagram of the thermodynamic cycle of the device 10 with respect to the organic fluid, according to a particular mode of implementation, using ethane as an organic fluid and natural gas as pressurized gas. unheated. The ordinate is in degrees Kelvin.

In this particular mode of implementation, the gas is first expanded by 2200 kPa; 288 K, ie 15 ° C, at 200 kPa by almost adiabatic expansion, that is to say with an isentropic yield of 85%. At the output of the gas regulator, the natural gas is thus at a temperature of 176 K, ie -97 ° C.

The gas then enters the exchanger 115 and is heated by the condensation of the organic fluid vapor. The natural gas is thus warmed by 176 K to a temperature of 218 K, ie -55 ° C.

This heating is represented in FIG. 3 by a line segment 305.

Furthermore, in the exchanger 115 of organic fluid, the organic fluid is condensed at a temperature of 225 K, ie -48 ° C, and a pressure of about 457 kPa. It is pumped at a pressure of about 1500 kPa, then vaporized at a temperature of 255 K, or -18 ° C, and overheated a few degrees. It is then relaxed to approximately 457 kPa.

This cycle is represented in FIG. 3 by a circuit of the fluid 310.

The organic fluid is vaporized by a hot source, which in a particular embodiment of the invention is ambient air. This is cooled from 293 K, ie 20 ° C, to 273 K or 0 ° C.

This cooling is represented in FIG. 3 by a line segment 315.

FIG. 4 shows a temperature-entropy diagram of the thermodynamic cycle of the device 10 in a case where the working fluid used is a mixture of fluids, called zeotropic, instead of a pure body. This zeotropic mixture vaporizes and condenses at a non-constant pressure and temperature. This characteristic of the mixtures makes it possible to better valorise the cold source and the hot source. Ideally, the vaporization curve of the zeotropic mixture T = f (S), where T is the temperature in K and S the entropy in kJ / kg / K, is a line of slope as close as possible to the slope made by the source. cold represented by a line segment 405. A zeotropic mixture is for example a mixture of ethane 85% by weight and methane 15%.

FIG. 5 shows a temperature-entropy diagram of the thermodynamic cycle of the device 10 in the case of the use of a heat source external to the device 10, such as a source of heat in the form of hot water or hot oil that can vaporize the organic fluid at a higher temperature than the ambient temperature. Under certain conditions, the industrial sites where the device 10 object of the present invention can be installed, may have industrial heat discharges in the form of hot water or hot air. Under these conditions, this hot source can be used to increase the efficiency of the overall plant and to cool the industrial thermal effluent. A more suitable organic fluid, having a boiling point for a pressure of 1 bar, more important in particular can be envisaged.

FIG. 6 diagrammatically shows a particular embodiment of a shaft 60 on which are combined on the same shaft 605 a turbine 610 that relaxes the unheated pressurized gas, a turbine 615 that relaxes the heated working fluid, and The two turbines, 610 and 615, are in cantilevered configuration so that the two bearings, 620 and 625, are located on the same side with respect to the turbine wheel. This shaft 60 further comprises a sealing device 630 allowing the organic fluid on the side of the turbine 615 for organic fluid not to be in contact with the gas under expanded pressure. Generator 635 can bathe in the expanded gas stream.

FIG. 7 diagrammatically shows a particular embodiment of an installation 70 for which integration is more important. The pressure reducers are combined on one and the same mechanical shaft as described with reference to FIG. 6. The outlets 705 and 710, the low pressure of each expander of the gas expander and the organic fluid expander, are connected directly to the same exchanger 715. which can be located above or next to the regulator block 720 having both regulators.

Thus, in the embodiment described with reference to FIG. 7, the unheated pressurized gas arrives in the gas holder via a connection 7625 and then encounters a fixed part or stator 730, then a moving part assembly before the gas holder. enter the exchanger 715 which heats this gas until the gas exits the exchanger 715 through an outlet 735.

On the other side, the heated and pressurized organic fluid vapor enters the device described with reference to FIG. 7 by an inlet connection at 740 and in a relaxed spring at the outlet 710 and enters directly into the exchanger 715, to come out condensed by an outlet 745.

FIG. 8 shows a succession of particular steps of the method 80 which is the subject of the present invention. This method 80 for extracting and recovering the expansion energy of an unheated pressure gas comprises: a step 810 of quasi-adiabatic expansion and thus producing mechanical energy on a rotating shaft of the gas entered in a pressure reducer, the pressure regulator comprising the rotating shaft; a heat exchange step 815 comprising: on the one hand: an inlet step 820 for the expanded gas; a step 825 for reheating the gas expanded by a vaporized organic fluid and a step 830 for exiting the heated expanded gas, and secondly for an inlet stage 855 for the vaporized organic fluid, the organic fluid having a boiling point below 40 ° C at ambient pressure; a step 850 for condensing and cooling the organic fluid during the heating of the expanded gas and an exit step 845 for cooled and condensed organic fluid; a closed circuit circulating step 890 for the organic fluid comprising: a step 860 displacement of the organic fluid at the output of the heat exchange step to a pump; a step 865 of displacement of the organic fluid from the pump to an evaporator exchanger; a step 870 of exchange by evaporation of the organic fluid; a step 875 of displacement of the organic fluid from the evaporator exchanger to a vaporized organic fluid expander; a step 880 of relaxing the vaporized organic fluid; a step 885 for displacing the organic fluid from the expander to serve as an organic fluid during the inlet step for the fluid of the heat exchange stage and, preferably, a step 835 for heating the exhaust gas of the exchange step 815 and an exit step 840 for the expanded gas downstream of the heat exchanger stage.

This method 80 is implemented, for example, by the device 10 described with reference to FIG.

Claims (8)

1. Device (10) for extracting and developing the expansion energy of an unheated pressurized gas, characterized in that it comprises: - a pressure regulator (110) of rotating machine type gas, comprising a freely rotating shaft (111) configured to effect a quasi-adiabatic expansion and thereby to produce mechanical energy on the rotating shaft, - a heat exchanger / heat exchanger (115) comprising: - an inlet (120) for relaxed gas; an inlet (125) for a vaporized organic fluid, the organic fluid having a boiling point below 40 ° C. at ambient pressure; an outlet (130) for heated expanded gas and an outlet (135) for cooled and condensed organic fluid; a closed circuit (140) for the organic fluid, called "ORC machine" (for Organic Rankine Cycle, translated by Cycle); Organic Rankine), connecting: - the output of the heat exchanger to a pump (155), - the pump to an evaporator exchanger (145), - the evaporator exchanger to a vaporized organic fluid expander (170) and the organic fluid expander at the condenser / heater heat exchanger, the expander being a rotating machine and performing a quasi-adiabatic expansion of the organic fluid, and producing mechanical energy on a rotating shaft and a connection ( 145) for the expanded gas downstream of the condenser / heater heat exchanger. 2. Device (10) according to claim 1, wherein at least one expander (110, 170) is a turbomachine, a shaft (111, 171) of each turbomachine being connected to a generator (180) configured to convert the energy mechanical produced by said expander in electricity. 3. Device (10) according to claim 2, wherein the shafts (111, 171) of each turbomachine are coupled to a common shaft (185). 4. Device (10) according to one of claims 1 to 3, wherein the flows of gas and / or fluid in the device are partially two-phase gas-liquid, with a vapor head greater than 80% by weight for the gas part. 5. Device (10) according to one of claims 1 to 4, which comprises, downstream of the outlet (130) for heated expanded gas of the exchanger (115) condenser / heater, a heat exchanger (144) gas heater relaxed warmed. 6. Device (10) according to one of claims 1 to 5, wherein the organic fluid is a zeotropic mixture. 7. Device (20) for enhancing and optimizing the expansion energy of a gas under unheated pressure, characterized in that it comprises: a first expander (211) of rotating machine type gas, comprising a rotational free shaft configured to perform a quasi-adiabatic expansion and thereby to produce mechanical energy on the rotating shaft, - a first condenser / heater heat exchanger (221) comprising: - an inlet (223) for the relaxed gas from the first regulator; an inlet (224) for a vaporized organic fluid, the organic fluid having a boiling point below 40 ° C. at ambient pressure; an outlet (225) for heated expanded gas and an outlet (226) for cooled and condensed organic fluid; a second expander (212) of rotating machine type connected to the expanded gas outlet of the first heat exchanger; comprising a rotational free shaft configured to effect a quasi-adiabatic expansion and thereby to produce mechanical energy on the rotating shaft, - a second heat exchanger / heat exchanger (222) comprising: - an inlet (227) for the expanded gas from the second expander; an inlet (228) for the organic fluid; an outlet (229) for warmed expanded gas and an outlet (230) for cooled and condensed organic fluid; a closed organic fluid circuit (240) called an ORC machine (for Organic Rankine Cycle). Organic Rankine), connecting: - the organic fluid outlet of each heat exchanger to a pump (261, 262), - each pump to an exchanger (270) evaporator, - the evaporator exchanger to an expander (271) of vaporized organic fluid and - the organic fluid expander at the inlet for organic fluid of each condenser / heater heat exchanger, the expander being a rotating machine and performing a quasi-adiabatic expansion of the organic fluid, and producing mechanical energy on a rotating shaft and - an outlet connection (255) for the expanded gas downstream of the second heat exchanger / heat exchanger. 8. Process (80) for extracting and recovering the expansion energy of an unheated pressure gas, characterized in that it comprises: a step (810) of quasi-adiabatic expansion and thus producing the mechanical energy on a rotating shaft of the gas entering an expansion valve, the expander comprising the rotating shaft, - a heat exchange step (815) comprising: on the one hand: a step (820) inlet for expanded gas; a step (825) for heating the gas expanded by a vaporized organic fluid and a step (830) for leaving the heated expanded gas, and secondly: an inlet step (855) for the vaporized organic fluid. the organic fluid having a boiling point below 40 ° C at ambient pressure; a step (850) for condensing and cooling the organic fluid during the heating of the expanded gas and a cooled and condensed organic fluid outlet step (845); a closed-circuit circulation step (890) for the fluid; organic composition comprising: a step (860) of displacement of the organic fluid at the outlet of the heat exchange stage to a pump; a step (865) of displacement of the organic fluid from the pump to an evaporator exchanger; a step (870) of exchange by evaporation of the organic fluid; a step (875) of displacement of the organic fluid from the evaporator exchanger to a vaporized organic fluid expander; a step (880) of relaxing the vaporized organic fluid; a step (885) of displacement of the organic fluid from the expander to serve as an organic fluid during the inlet step for the fluid of the heat exchange stage and - a step (840) of exit for the expanded gas downstream of the heat exchanger stage.