NL7905843A - DEVICE FOR EXTRACTING ENERGY FROM GAS WITH LOW HEATING VALUE. - Google Patents

Description

4 - 1 - if ΙΓ.Ο. 27,956

Gulf Research & Development Company, in PITTSBURGH, Pennsylvania, Yer. St. America

Device for recovering energy from gas with low heating value____

The present invention relates to the recovery of energy from gas with a low heating value and more particularly to a gas turbine system adapted to use such a gas for; i generating energy. ; One method for increasing the production * of heavy crudes of high viscosity from substrate; se formations is the in-situ combustion process. In this method, air is injected at a high pressure through an injection well into the underground formation, which is the heavy; 10 contains oil. The oil in the formation is ignited adjacent to the injection well by any of the known methods, as described, for example, in U.S. Patent No. 5,172.4-72. Injection of air is continued after ignition to burn some of the oil in the formation and increase the pressure in the formation adjacent the injection well, thereby propelling oil in the formation to a production well remote from . the injection well is present. An in-situ combustion process is described in U.S. Patent 2,771,951. 20 "The by burning part of the oil in the forma-;

i I

This release of heat heats the formation and the oil, i: which considerably reduces the viscosity of the oil j. is due to the high temperature, cracking of the oil and; by solution in the oil of low 25 hydrocarbons

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Molecular weight formed during cracking. The reduced viscosity and pressure of the injected gas flows the oil through the underground formation to a production well.

During in-situ combustion processes, the combustion front, burning oil in the formation, does not move radially outward from the injection well at an even speed in all directions. Some of the injected air passes in the form of fingers through zones of high permeability in the formation to a production well and combustion occurs at the interfaces of the fingers. There is usually a breakthrough of combustion products as a combustion gas long before the production of oil by the in-situ process is completed. Volatile constituents in the oil or formed upon cracking the oil are entrained in the injected air or combustion gases and thereby transferred to the production well. All these factors contribute to an unevenness in the composition and heating value of the gas produced.

The streams generated at the production well are separated into liquid petroleum products, which are delivered for storage or to a delivery line and gaseous products. The gaseous products are usually vented to the atmosphere. The gaseous products, hereinafter referred to as LEV gas (low heating value gas), from the in-situ combustion of heavy petroleum contains low concentrations of methane and hydrocarbons with 2 to 6 carbon atoms, as well as nitrogen, carbon dioxide, sulfur compounds, such as hydrogen sulfide, mercaptan and carbonyl sulfide and in some cases a small amount of carbon monoxide. These gaseous products 30 form the low heating fuel capable of providing a substantial portion of the energy required to compress the air for injection into the underground formation at the injection well. The shortage of natural gas makes it important that the energy is fully utilized in the production of an in-situ combustion process 7905843 3. In addition, the tightening of atmospheric pollution laws imposes stricter restrictions on the amount of carbon monoxide, the sulfur compounds, which are commonly present in the gaseous products, and hydrocarbons other than methane, which can be released to the atmosphere. .

US patent 3,116,620 discloses an in-situ single well combustion process in which a void filled with debris is formed in an underground oil slate deposit by means of a nuclear explosion. An in-situ cavity combustion process is then performed to remove oil from the rock, promote the draining of the oil into a reservoir in the bottom of the cavity, and force the oil upward through the well to the surface. The gas generated with the oil in the in-situ combustion of oil slate contains a higher concentration of carbon monoxide than gas obtained by a conventional in-situ combustion process in an oil reservoir. Since gas obtained from oil slate has a high concentration of carbon monoxide and hydrogen compared to the off-gas from the in-situ combustion in petroleum reservoirs, the oil-slate off-gas can in some cases be burned directly in a flame burner a gas turbine, which is used to drive an air compressor.

In a lecture entitled "Power Generation from Shale Oil Process Off-Gas" by "JM McCrank and GK Short held at the IEEE-ASME Joint Power Generation Conference in Buffalo, Η.Γ., Sept. 19-22, 1976, Describes the results of a technical study of the generation of energy from the waste gas from the in-situ combustion of oil-slate Waste gas from the oil-slate is burned according to a flame-type combustion to obtain hot combustion products used to drive a gas turbine As mentioned above, 7905843 4, the high concentration of carbon monoxide in the waste gas from the in-situ retort combustion of oil-slate facilitates flame combustion, but variations in the composition of the waste gas can make maintenance of a stable flame uncertain

A talk entitled "Catalysts for Gas Turbine Combustors-Experimental Test Results" by SM, DeCorso, S. Mumford, R. Carrubba, and R. Heek, delivered at the March 21-25, 1976 meeting of The American Society of Mechanical Engineers described the combustion of a fuel, which is described as a low calorific value gas in a catalytic combustion chamber at a laboratory. The low calorific value gas is further identified as synthetic carbon gas with a heating value of 4693 kJ / m 2. The combustion; was performed by bringing a mixture of the gas and preheated air to a temperature at which the catalytic thermal combustion of the type disclosed in U.S. Patent 3,928,961 occurs.

In this method, the mixture of fuel and air 20 near the catalyst surface is at a temperature, where. thermal combustion occurs at a rate higher than the catalytic rate and the catalyst surface is above the instantaneous ignition temperature of the fuel-air mixture. 25

The present invention resides in the system of recovering energy from low heating value gas (LHV gas) as obtained in an in-situ combustion process for petroleum recovery or an in-situ combustion process for the retort treatment of oil slate. EHY gas is mixed with air and heated to a temperature at which combustion of the LHY gas will be initiated upon contact with an oxidation catalyst. The system comprises a gas turbine with an external combustion device, which contains a first and a second stage of a catalytic combustion space 7905843 5 with a heat exchanger between the combustion spaces.

The mixture of air and gas is passed through the heat exchanger before delivery to the first stage catalytic combustion space and is heated there by indirect heat exchange with combustion products discharged from the first stage catalytic combustion space. Means for providing control of the air flow rate for limiting the maximum temperature rise, avoiding excessive temperatures in the external catalytic combustion space by maintaining a sub-stoichiometric air flow in the combustion device.

Fig. 1 is a schematic representation of a system for recovering energy from LEV gas from an in-situ combustion process for petroleum production, the IHV gas being supplied at a pressure high enough to drive a turbine.

Fig. 2 is a schematic representation of a system for use in recovering energy from an LHV gas supplied at a low pressure. 20

Referring to FIG. 1, a bottom oil reservoir 10 containing crude oil, usually of high density and viscosity, is penetrated through a production well 12 and an injection well 14 remote from the production well. Streams obtained from the production well 12 are passed through a conduit 16 to a separator 18, in which the LHV gas obtained is separated from liquids generated by the well 12. The liquids are vented at the lower end of the separator 18 to a delivery line 20 and the LHV gas is vented from the top of the separator into a supply line 22. It will usually be desirable to pass the gas from the separator 18 through a suitable gas cleaner, indicated through 24, to remove solids, catalyst poisons, or other unwanted components 55 before delivery to 7905843. 6 energy recovery system. It is important for the efficient operation of a gas turbine that variations in the mass flow from gas to the turbine are minimized. A flow control device 26 maintains a constant flow rate of the LH7 gas in the system.

Usual hydrocarbon concentrations in the HTV gas range from about 1 to 8% by volume. The hydrocarbons mainly consist of methane; the concentration of hydrocarbons with 2 to 6 carbon atoms is usually less than 2%. The heating value of the LHV gas obtained from an in-situ combustion in oil reservoirs can range from 185 to 2985 kJ / m 2 and will usually range from 1505 to 2595 kJ / m 2, a range in which this method is particularly suitable. With the concentrations of hydrocarbons usually present in LHV gas obtained by in-situ combustion in oil reservoirs, stable combustion of methane and the other low molecular weight hydrocarbons produced in the in-situ production cannot be obtained. in the absence of an oxidation catalyst, but are only obtained in the presence of a catalyst.

LEV gas with a heating value greater than 560 kJ / m2 can be burned in a catalytic combustion device without an external heat source. When other heat sources are available to provide the additional preheating, LHV gas with a heating value of only 185 kJ / m2 can be oxidized in catalytic combustion spaces.

For the most effective use in driving a gas turbine to compress air used in the in-situ combustion process, for example, the gases discharged from the separator 18 should have a pressure of at least 516 kPa. When the gas is at a lower pressure, some of the energy generated by the gas turbine is used to compress the LEE 7905843 7? gas to a pressure high enough to drive a turbine, as described with reference to Fig. 2. The pressure in the production wells of an in-situ combustion process in an oil reservoir can range from slightly above atmospheric pressure to 5516 kPa. The pressure depends, at least in part, on the depth of the formation in which combustion takes place. Pressures higher than 5516 kPa in the production wells can be used, but such high pressures suffer from disadvantages of high cost of compressing the air injected into the underground formation.

When the gas turbine starts up, LH? gas is supplied through line 22 to a preheater 28, in which the gas is heated to such a temperature that when the LEV gas, mixed with air, contacts the catalyst, combustion of the LEV gas will occur. The preheater is heated by a fuel such as natural gas, propane or LPG supplied through line 30. If desired, the combustion air for combustion in the first stage catalytic combustion chamber, described below, can be mixed with LHV gas before the LH? gas is passed through the preheater 28.

The mixture of air and LH? gas fed to the catalytic combustion space should have a temperature of at least 204 ° C and preferably from 316 to 4-27 ° C to initiate combustion. The preheater is only used during start-up. After the catalytic combustion of the first stage has been initiated, the LEV gas is passed around the preheater 28 through bypass line 32 and the valves at the inlet and outlet of the preheater are closed.

In the embodiment, as illustrated in Fig. 1, the LH? gas from the preheater 28 during start-up or from the bypass line 32 thereafter fed to a line 34, in which it is mixed with primary combustion air supplied from a first combustion air line 56. The mixture is supplied to a hot exchanger 58, where it passes in indirect heat exchange with hot combustion products from the first stage catalytic combustion space, as described below 5, to heat the mixture to a temperature above about 204 ° C, preferably 516 to 427 ° C , which initiates combustion upon contact with the catalyst. The heated mixture of LHY gas and air is supplied from heat exchanger 58 through line 40 to the inlet end of the primary catalytic combustion chamber 4-2. In a preferred structure, the catalytic combustion space 42 includes a plurality of spaced-apart permeable discs 44 arranged transversely of the combustion space on which a catalytically active platinum group metal is applied.

The spaces 46 between the disks allow for remixing of the burn products from the disks to prevent hot spots from developing in the catalyst. 20

The disks 44 are preferably of a honeycomb ceramic or other configuration with passages extending from the inlet side to the opposite side of the disks to allow passage of the gases longitudinally through the primary combustion space 42. Catalysts that can be used are described in U.S. Patent Nos. 5-870,455 and 5,565 * 850. The present invention is not limited to the use of a particular catalyst support or a particular catalytic material. 50

Other oxidation catalysts such as cobalt, lanthanum, palladium, rhodium, nickel, iron or other types of supports, such as granules, saddles or rings of refractories, can be used.

The combustion products of the primary catalytic combustion chamber are vented at about 790 58 43 9 871 ° C through line 48 and fed to the heat exchanger 38 for heat transfer with the LHV gas-air mixture fed through line 36. The heat exchanger 38 is preferably a house and shell type heat exchanger, wherein the hot combustion products pass through the tubes and the IHV gas-air mixture passes over the outer wall of the tubes and through the space between such outer walls and the shell of the heat exchanger. In a preferred embodiment of the invention, secondary air from combustion in a secondary catalytic combustion space 54 of unburned combustible material in the combustion products is exhausted from the combustion space 42, supplied through a conduit 50 to conduit 48, in which the air is mixed with the combustion products discharged from the combustion chamber 42 before supplying to the preheater 38. The mixing of the secondary air with the exhaust stream from the first combustion chamber 42 usually lowers the temperature by about 110 ° C.

Hot combustible gas mixed with secondary air 20 is supplied at a temperature from 204 ° C to 427 ° C, preferably from 316 ° C to 427 ° C, from the heat exchanger 38 through line 52 to the supply end of the secondary catalytic combustion chamber 54. The secondary catalytic combustion chamber 54 is preferably similar to the combustion chamber 42. Combustible compounds remaining in the products discharged from the combustion chamber 42 are oxidized in the combustion chamber 54 and discharged from this combustion chamber to a hot gas lodging 56. 30

Combustion of flammable compounds, mainly hydrocarbons, in the IHV gas releases heat, which increases the temperature of the gases in the combustion chamber to a temperature that does not exceed the maximum allowable operating temperature of the catalyst. 35

Preferred catalysts which are currently commercially available have a maximum operating temperature of about 871 ° C. The catalysts can be used at higher temperatures, but higher temperatures will shorten the life of the catalyst. The control of the temperature in the catalytic combustion chamber 42 is accomplished by limiting the amount of air supplied to the combustion chamber to an amount which, when fully consumed in combustion, will limit the temperature rise to the desired range. Combustion in the combustion space 42 is always with an amount of air less than the stoichiometric equivalent of the flammable components in the LHV gas. Combustion control in the LHV gas by controlling the amount of air supplied to the combustion spaces to an amount lower than the stoichiometric equivalent of the flammable components in the LHV gas makes the maximum temperature independent of the heating value of the LHV gas. Variations in the heating value of the gas cannot cause excessive catalyst temperatures. The avoidance of excessive temperatures by maintaining an air flow rate to the catalytic combustion chambers, which limit the maximum temperature rise beyond the heating value of the LHV gas, is described in U.S. Patent Application 791,850 (1977). The temperature restrictions in the secondary combustion space 54 are the same as in the primary combustion space 42. The maximum temperature rise in the combustion space 54 is limited by limiting the amount of air supplied through line 50 to an amount that will be completely den consumed by combustion of flammable components, which will raise the temperature to the desired maximum; consequently, a sudden increase in the heating value of the LHV gas will not result in excessive temperatures. Preferably, about half of the 55 total combustion air is supplied to each of the combustion rooms.

Hot gas is supplied through line 56 to the inlet side of a gas turbine, as generally indicated by reference number 59, in which the gas is expanded to drive the turbine and rotate a drive shaft to provide energy. When the hot gas in line 56 is at a temperature above the maximum operating temperature of the turbine, the gas is cooled to the desired temperature by dilution air supplied through line 57 • Pray in the absence of the catalyst, dilution air will not burn combustibles in the cause hot gas. In the embodiment of the invention illustrated in Figure 1, the gas turbine 59 includes two sections, a first section 58 and a second section 60. Expanded gas from section 58 is supplied to the inlet of the second section 60 where further expansion before it. waste gas is vented to atmosphere through a conduit 62.

Section 58 of the turbine drives shaft 65 to rotate an air compressor 66. Compressed air from compressor 66 is exhausted to a line 68, from which compressed air is supplied to lines 56, 50, and 57. A different portion of the compressed air from compressor 66 is drawn air supplied through a conduit 70 to an air compressor 72 driven by a second section of the gas turbine to provide air for the in-situ combustion process.

Air exhausted from the air compressor 72 is supplied through a conduit 74 to an air compressor 76 for compression to an appropriate pressure for injection in formation 10 for the in-situ combustion process.

In the operation of the device illustrated in Fig. 1, LHV gas discharged from the flow control device 26 is supplied during start-up through line 80 to a start-up turbine 82. The start-up turbine 55 82 is connected by shaft 84- to a suitable coupling. 86 790 58 43 12 to the air compressor 66. LHV gas vented from the start-up turbine 82 is vented to the atmosphere.

A portion of the LHV gas stream is supplied through line 22 to the preheater 28, where the gas is heated by indirect heat transfer with hot combustion products from the combustion of a fuel 30.

Air from compressor 66 is supplied through line 36 for mixing with the LHV gas from preheater 28 and the mixture is passed through heat exchanger 38.

At the start of the start-up, no heating of the LHV gas-air mixture takes place in the heat exchanger.

The hot LHV gas-air mixture flows into the primary combustion chamber 42, where the mixture first heats the catalyst to reaction temperature and then burns in a catalytic oxidation. 15

Hot combustion products vented from the catalytic combustion chamber 42 are mixed with secondary air supplied through line 50 and passed through heat exchanger 38 in indirect heat exchange with the LHV gas-air mixture, to be supplied to the primary catalytic combustion chamber 42. The secondary air mixture and partially burned LHV gas, discharged from the heat exchanger 38, is supplied through line 52 to the secondary catalytic combustion chamber 54, where additional combustion takes place. The combustion products discharged from the secondary combustion space 54 usually have a temperature of about 871 ° C. This hot mixture is passed through line 56 into gas turbine 58. It is usually desirable to operate the gas turbine at a temperature of 760 ° C to 813 ° C. 30

Cooling of the hot gases in line 56 is accomplished by mixing these gases with dilution air supplied through line 57.

After combustion has been initiated into the primary combustion space 42, the flow of LHV gas to the preheater 28 is interrupted and LHV gas is passed through conduit 32 through bypass line 32. The flow rate of LHV gas is gradually increased to load the turbine 58. When the gas turbine 58 takes over the load from the compressor 66, coupling 86 is interrupted to separate the start-up turbine 82 from the compressor 66 and the valve in line 80 is closed to stop the flow of LHV gas to the start-up turbine 82.

The variations in the composition of LHV gas generated from time to time in an in-situ combustion process may result in a drop in the heating value of the gas to such a level that the temperature of the products discharged from the secondary combustion space 54- is lower than the desired temperature.

To maintain the most efficient operation of the gas turbine, samples of LEV gas are taken from line 22 and passed through a hydrocarbon analyzer 88 to determine the heating value of the LHV gas. Hydrocarbon analysis devices are commercially readily available devices. The analyzer 88 20 outputs a signal which is supplied to the control valve 90 in an auxiliary fuel line 92. When the heating value of the LEV gas drops to a level, the temperature of products discharged from the second combustion space is less than desired, valve 99 provides auxiliary fuel through line 92. The air supplied through lines 36 and 50 is sufficient to allow suitable combustion to raise the temperature to the desired level, but is not sufficient to produce excessive temperatures if the heating value of the LHV gas suddenly increased. If the temperature in line 56 should drop below the desired temperature, a signal generated by temperature response means can be used to control the valve in line 50 to increase the secondary air.

790 58 43 -. 14

The apparatus illustrated in Fig. 3 is for LHV gas initially supplied at a low pressure, as will usually be generated in the in-situ combustion of oil slate. Since the LEV gas is at a pressure that is too low to efficiently drive a turbine, it is necessary to compress the LHV gas to a higher pressure, which will allow efficient operation of the gas turbine. In general, an initial LHV gas pressure of at least 516 kPa is required for the efficient use of a gas turbine. For this purpose, an LHV gas compressor 100 is mounted on the same axis as compressor 66. A primary start-up device 102, which may be a diesel engine, electric motor, etc., is adapted to connect the LHV gas compressor 100 through an axis 104 to float. A clutch 106 allows the release of the starter motor 102, after the gas turbine 58 is brought up to speed, to drive the LHV gas compressor 100 and the compressor 66.

The apparatus illustrated in FIG. 2 is similar to that in FIG. 1 in the arrangement of the air compressor 20 66, external catalytic combustion chambers 42 and 54, heat exchanger 38 and gas turbine 59. Since it is necessary to compress the LHV gas, as well as the * compressing air for the combustion of the LHV gas, the amount of air compressed by compressor 66 may be suitable for combustion of the LHV gas only.

There will then be no air draw from compressor 66 to the suction side of a compressor driven by section 69. For example, section 60 may power an electric generator, which is indicated by reference number 108. 30

The gas turbine described here allows the recovery of energy from gaseous fuels with a heating value too low for the conventional gas turbine, in which flame combustion is used for the combustion of the fuel. The catalytic combustion device provides a stable combustion of 7905843.

fuels with heating values well below the heating value of gases that will provide a stable flame and are particularly valuable in the useful use of low heating fuels in which the main combustible component is methane, a fuel which is difficult to burn. The two-stage catalytic combustion chamber with an interstage heat exchanger provides a self-contained unit, which will increase the IHV gas-air mixture to catalytic oxidation temperatures without the use of an external heat source and avoids excessive catalyst temperatures . The device is particularly valuable for the useful use of gases from in-situ combustion processes for oil production.

7905843

Claims (16)

1. Apparatus for recovering energy from LHV gas discharged from an in-situ combustion process, characterized by a gas turbine, an air compressor driven by the gas turbine, an external combustion device for burning the LHY gas, the combustion device having a catalytic combustion space of the first stage and a catalytic combustion chamber of the second stage, a heat exchanger. "between the first stage catalytic combustion chamber 10 and the second stage catalytic combustion chamber, for combustion products discharged from the first stage catalytic combustion chamber" by feeding the heat exchanger to the second stage catalytic combustion chamber, an LHV gas line 15 to the heat exchanger for delivering the LHV gas from the in-situ combustion process to the heat exchanger, which heat exchanger is constructed and arranged to pass the LHV gas in indirect heat exchange with the combustion products of the first stage catalytic combustion chamber , a conduit from the heat exchanger to the inlet of the first stage catalytic combustion chamber, which conduit communicates through the heat exchanger with the LHV gas conduit for the delivery of LHV gas to the catalytic combustion chamber of the first stage, a conduit for hot gases from the discharge of the second stage catalytic combustion chamber to the gas turbine for delivering hot combustion products to the gas turbine and an air line from the air compressor, 50 connected for supplying compressed air to the LHV gas before entering the catalytic combustion chamber of the first stage and gas delivered to the second stage catalytic combustion chamber. 35 An apparatus according to claim 1, characterized in that the air line from the air compressor comprises a first line to the LHV gas line for supplying compressed, primary combustion air to the LIV gas before the LHV gas is delivered to the heat exchanger. 5 3. Device according to claim 2, characterized in that the air conduit from the air compressor comprises a second conduit arranged to deliver air to the products of combustion discharged from the catalytic combustion chamber of the first stage, prior to on entry of these combustion products into the heat exchanger. 4. Device according to claim 1, characterized in that the heat exchanger is a tube and body exchanger, constructed and arranged to pass the combustion products through the tubes and to transfer the LHV gas between the external surface of the tubes and the body. lead. Device according to claim 1, characterized by a cool air conduit opening in the hot gas conduit 20, a signaling means responsive to the temperature of the hot gas in the hot conduit and a flow control device in the cooling air supply conduit responsive to a signal from the signaling device in the hot gas conduit for controlling the flow rate of the cooling air to maintain the temperature of gas delivered to the turbine below a predetermined maximum. 6. Apparatus according to claim 5j, characterized in that the refrigerant gas pipe extends from the compressor outlet to the hot gas pipe. 7. Device according to claim 5, characterized by the flow control device in the cooling air line, constructed and arranged such that the flow of cooling air is increased in response to 7905843 '' 18 hot gas temperatures higher than a predetermined temperature, an auxiliary fuel line connected to auxiliary fuel to be delivered to the external combustion device, a device for recording the heating value of the LEV gas and a flow control device in the auxiliary fuel line responsive to the heating value of the LEV gas, adapted to allow flow of auxiliary fuel , when the heating value of the LEV gas falls below a predetermined minimum. 10 8. Device according to claim 7? characterized in that an opening of. the auxiliary fuel line is present in the LEV gas line. 9. Device according to claim 6, characterized by a second air compressor driven by the gas turbine, an air line from the compressor outlet adapted to deprive air from the second air compressor in excess of the amount discharged from the compressor to the catalytic combustion spaces and to the hot gas pipe. 20 10. Device according to claim 9, characterized in that the gas turbine comprises two sections, each of these sections driving a separate shaft, the air compressor being driven by one shaft and the second air compressor being driven by the other shaft. 11. Device according to claim 3 - characterized by hot-gas signaling devices responsive to temperature and a flow control device in the second air conduit responding to the hot-gas signaling device responsive to the temperature, adjusted to increase the air strip in the second line. 12. Device according to claim 1, characterized by the catalytic combustion spaces, comprising a tubular space, a plurality of longitudinally spaced disks of a ceramic catalyst support extending transversely across the space, passages extending through the discs from one side to the opposite side to allow longitudinal flow through the catalytic combustion chambers and an oxidation catalyst deposited on the discs · 13. Device according to claim 7, characterized in that the oxidation catalyst is platinum. 14. Device according to claim 1, characterized by an LHV gas compressor driven by the gas turbine and an LHV gas pipe, comprising a pipe from the source of the LHV gas to the LHV gas compressor inlet and a pipe from the LHV gas compressor outlet to the heat exchanger. 15 Gas turbine system for recovering energy from LHV gas, characterized by a catalytic combustion device for burning the LHV gas to generate a hot gas for driving the gas turbine, which combustion device has a primary catalytic combustion space and a secondary catalytic combustion space, which primary and secondary combustion spaces contain a solid oxidation catalyst, which is assembled and arranged such that intimate contact with and a low pressure drop in the gas takes place with the gas passing through the combustion spaces, a heat exchanger between the primary and secondary combustion spaces, a conduit from the primary combustion space to the heat exchanger and from the heat exchanger to the secondary combustion space, assembled and arranged to deliver gas discharged from the primary combustion space to the heat exchanger and from the heat exchanger to the se secondary combustion space, a first LHV gas line for delivering LHV gas to the heat exchanger 35 for indirect heat exchange with the gas, which is discharged from the primary combustion space, a second LIV gas line for delivering LHV gas from the heat exchanger at the inlet of the primary combustion chamber, an air line, assembled and arranged to deliver air to the LÏÏV gas, before the LÏÏV 5 gas enters the primary combustion chamber and discharged to the gas to the primary combustion chamber, before this gas enters the secondary combustion space and contains a hot gas conduit from the discharge of the second combustion space to the gas turbine. 10 Device according to claim 1, characterized by a LÏÏV gas compressor driven by the gas turbine and the LÏÏV gas pipe to the heat exchanger, which comprises a pipe from the in-situ combustion process to the inlet of the LÏÏV gas compressor 15 and a pipe from the outlet of the LHV gas compressor to the heat exchanger. ******** 7905843