METHOD FOR ACCUMULATING AND PRODUCING ENERGY ASSOCIATED WITH OXY-COMBUSTION WITHOUT GREENHOUSE GAS EMISSIONS

Description

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a National Stage Application of PCT International Application No.: PCT/IB2023/056839 filed on Jun. 30, 2023, which claims priority to Italian Application 102022000013873, filed in the Italian Patent Office on Jun. 30, 2022, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

There are multiple technologies for both the storage and the production of electricity.

As for the storage, the best known are: electrochemical (batteries), mechanical (flywheels, compressed air, accumulation of water at high altitude), thermodynamic (liquefied gases: liquid air, referred to as Liquid Air Energy Storage, LAES) technologies.

Instead, as for the production of energy, it can be produced from a fuel by sequestering combustion CO₂, through carbon capture techniques from combustion fumes, or through combustion in a synthetic atmosphere mainly consisting of CO₂ and oxygen, conducting an oxy-combustion, with which the fuel and oxygen are converted into CO₂ and water and then removed from the system.

The oxy-combustion process is configured as an energy production system, possibly to be used to cover network demand peaks, but is not an energy accumulation system per se.

The oxy-combustion process requires the production of oxygen with a purity greater than 90% and this, in turn, entails the compression and purification of large amounts of air, most of which, once the oxygen is extracted, is simply released into the atmosphere.

The process of separating oxygen from air is also expensive, since in order to avoid compressing a much greater amount of air than that required to obtain oxygen therefrom, it requires sophisticated technical expedients which maximize the efficiency thereof.

Typically, oxy-combustion plants are heavily penalized by the operations of extracting oxygen from the air and liquefying combustion CO₂.

To date, the most efficient oxy-combustion cycles with complete CO₂ sequestration are the Allam cycle and the Graz cycle, which have an efficiency, calculated with respect to the lower calorific value of the fuel and the energy invested in the production of the comburent (high purity oxygen), equal to about 52%.

It is also worth noting that the Allam cycle requires to cool the recirculation CO₂ to a temperature not exceeding 16° C., which requires an adequate cold well, not always available in relation to the season, geographical position, and possibly the availability of a body of water.

Although the oxy-combustion cycles do not release combustion CO₂ into the atmosphere, the problem of the permanent storage thereof remains: it is estimated that the spent hydrocarbon wells would not be enough to contain all the CO₂ currently produced in a year.

For this reason, these technologies are not developed, also because they tend to move a problem over time, rather than solving it.

For its part, LAES has a considerable energy expenditure for the production of liquid air, which the inventors estimate at 0.45 kwh/kg, and this strongly limits the amount of recoverable energy: in fact, a demonstrative plant of this type does not exceed an efficiency of 15%.

This is mainly due to the fact that among the fluids available for a condensation/evaporation cycle which does not require to store the gas, the air must reach low temperatures and therefore the amount of energy required for condensation is so high as to enhance the thermodynamic inefficiencies of the process.

Italian patent application IT 2020 0002 3167 (Saipem S.p.A.) describes the combination of an oxy-combustion cycle with LAES energy accumulation technology.

International patent application WO 2021/255578 (Energy Dome S.p.A.) describes a plant for generating and accumulating energy, in which a closed thermodynamic cycle is integrated with oxy-combustion technology.

Patent application US 2019/211715 describes the separation of hydrogen and carbon monoxide from a gaseous fuel, a combustor supplied with carbon monoxide, and a carbon dioxide separation unit, for preparing carbon dioxide in the supercritical state.

SUMMARY OF THE INVENTION

The inventors of the present patent application have surprisingly developed a method which allows storing available excess electricity in the form of liquid gases, in particular carbon monoxide and oxygen, to be then employed in an oxy-combustion cycle with energy production, integrating therebetween the technologies of oxy-combustion, dry carbon dioxide electrolysis, and energy storage in the form of frigories.

OBJECT OF THE INVENTION

In a first object, the present invention describes a method for producing and accumulating energy, producing carbon monoxide and ultra-pure oxygen, as well as for using carbon dioxide.

In a second object, the present invention describes a method for generating power.

The present invention globally describes a method for producing and accumulating energy, producing carbon monoxide and ultra-pure oxygen, as well as for using carbon dioxide and producing liquid carbon dioxide.

In a particular aspect, the method of the invention allows the management of energy peaks and deficiencies (peak shaving).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the thermodynamic aspects of the process of the present invention.

FIG. 2 depicts an embodiment of the accumulation step of the method of the present invention.

FIG. 3 depicts an alternative embodiment of the accumulation step of the method of the present invention.

FIG. 4 depicts an embodiment of the generation step of the method of the present invention.

FIG. 5 depicts an alternative embodiment of the generation step of the method of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

For the purposes of the present invention, the heat exchanges conducted in the exchangers (E1, E2, E3, E4, En) are conducted with external fluids, preferably air, water, etc.

The heat exchangers (indicated by “EXn”) instead involve two flows inside the circuit(s) described in the invention.

In accordance with a first object of the present invention, there is described a method for producing and accumulating energy, producing carbon monoxide and ultra-pure oxygen, as well as for using carbon dioxide.

Said carbon dioxide can be produced, for example, by industrial or refinery processes or even environmental processes, avoiding the release thereof into the atmosphere.

The method of the present invention also allows managing energy peaks and deficiencies (peak shaving).

In particular, the energy accumulation is obtained by storing carbon monoxide and oxygen, at least partially liquefied, and a cooled fluid.

In particular, such a method comprises an accumulation step A) and a generation step B).

For the purposes of the present invention, the accumulation step A) is a step which allows producing a flow of carbon monoxide (CO) and oxygen and possibly a cooled fluid.

In particular, in step A) the production of carbon monoxide (CO) and oxygen is obtained by carbon dioxide electrolysis.

More in particular, such a step A) is conducted using excess electric current available in the network.

The term “available in excess” means an amount of electricity greater than that required.

According to an aspect of the invention, carbon monoxide and oxygen can be accumulated in the form of at least partially liquefied storages.

For the purposes of the present invention and with reference to the method depicted in FIG. 2, step A) comprises the sub-steps of:

• • A1) electrolyzing an appropriately-heated carbon dioxide flow 3 and obtaining an initial carbon monoxide flow c1 and an initial oxygen flow o1,
  • A2) obtaining an at least partially liquefied carbon monoxide flow c17 from the initial carbon monoxide flow c1,
  • A3) obtaining an at least partially liquefied oxygen flow o10 from the initial oxygen flow o1.

As for the electrolysis step A1), this is conducted in an electrolytic cell EL from an appropriately heated carbon dioxide flow 3 obtained from liquid carbon dioxide and possibly also from gaseous carbon dioxide.

In particular:

• • in a step A0a), an initial liquid carbon dioxide flow 1 is withdrawn from a liquid carbon dioxide tank TCO2l and heated by heat exchange in a first sector of a first heat exchanger EX1a, thus obtaining a heated carbon dioxide flow 2, and
  • in a step A0b), said heated carbon dioxide flow 2 is further heated by heat exchange in a second heat exchanger EX2, thus obtaining said appropriately heated carbon dioxide flow 3.

According to an aspect of the present invention, a step A0a′) can be conducted, in which a second initial liquid carbon dioxide flow 1″ is pumped in a pump P, thus obtaining a second pumped liquid carbon dioxide flow 2″ which is then heated by heat exchange in the first sector of a first heat exchanger EX1a, thus obtaining a second heated carbon dioxide flow 3″, which can be stored in special storage wells.

According to an aspect of the present invention, a step A0b′) can be conducted, in which an initial gaseous carbon dioxide flow 1′ can be heated in the second heat exchanger EX2, thus obtaining a heated gaseous carbon dioxide flow 2′, to be joined to the suitable flow 3.

According to an aspect of the present invention, the electrolytic cell EL is preferably a solid oxide cell (SOEC).

As described above, two flows are obtained from step A1), namely:

• • a flow, hereinafter referred to as the initial carbon monoxide flow c1, comprising carbon monoxide and carbon dioxide, and
  • a flow, hereinafter referred to as the initial oxygen flow o1, comprising 99.9% pure oxygen.

According to a particular embodiment of the present invention, step A1) can comprise producing power by exploiting the heat produced by Joule effect from the electrolytic cell, as will be described hereinafter.

As for the step A2) of obtaining an at least partially liquefied carbon monoxide flow c13 from the initial carbon monoxide flow c1, this comprises the further sub-steps of:

• • A2a) obtaining a carbon monoxide flow to be purified c6,
  • A2b) obtaining a mainly carbon monoxide and vapor flow c12, a recycled carbon monoxide flow c11, and a recirculation gas flow cr,
  • A2c) obtaining a dehydrated carbon monoxide flow c13,
  • A2d) obtaining an at least partially liquefied carbon monoxide flow c17.

In particular, step A2a) comprises the still further sub-steps of:

• • A2a1) obtaining a first initial carbon monoxide flow portion c2 and a second initial carbon monoxide flow portion c2′,
  • A2a2) cooling said first initial carbon monoxide flow portion c2 in a third heat exchanger EX3a, thus obtaining a first cooled initial carbon monoxide flow portion c3,
  • A2a3) cooling said second initial carbon monoxide flow portion c2′ in another third heat exchanger EX3b, thus obtaining a second cooled initial carbon monoxide flow portion c3′,
  • A2a4) joining said first cooled initial carbon monoxide flow portion c3 and said second cooled initial carbon monoxide flow portion c3′, thus obtaining a joined cooled carbon monoxide flow c4,
  • A2a5) subjecting said joined cooled carbon monoxide flow c4 to compression in a first compressor cC1, thus obtaining a compressed carbon monoxide flow c5, and to cooling in a first exchanger cE1, thus obtaining said carbon monoxide flow to be purified c6.

For the purposes of the present invention, step A2a5) can possibly be repeated if needed until the necessary conditions for the next step A3) are achieved.

Advantageously, step A2a5) allows an easier separation of carbon monoxide from carbon dioxide and improves the heat exchange profile in the carbon monoxide liquefaction process.

In an embodiment of the present invention, the initial carbon monoxide flow c1 is not separated and is sent entirely to a third exchanger EX3.

For the purposes of the present invention, sub-step A2b) comprises the still further sub-steps of:

• • A2b1) subjecting the carbon monoxide flow to be purified c6 to a first purification in a first purification column CL1 and obtaining a partially purified carbon monoxide flow c7, a physical solvent-released carbon monoxide flow c8, and a recycled carbon monoxide flow c11,
  • A2b2) subjecting the partially purified carbon monoxide flow c7 to a second purification in a second purification column CL2, thus obtaining a mainly carbon monoxide and vapor flow c12, a flow to be regenerated m2, and a recirculation gas flow cr.

For the purposes of the present invention, the mainly carbon monoxide and vapor flow c12 has a carbon dioxide concentration less than 500 ppm (mol/mol) and preferably less than 50 ppm (mol/mol).

More in particular, said step A2b1) comprises the following steps:

• • p1) washing with a physical solvent,
  • p2) separation from the physical solvent, thus obtaining a regenerated physical solvent flow s9 and a physical solvent-separated flow c8,
  • p3) compression and cooling, thus obtaining a physical solvent-separated compressed flow c9 and cooled c10,
  • p4) dehydration in a first Dehydration Unit cDU1, thus obtaining the recycled carbon monoxide flow c11.

For the purposes of the present invention, the recycle flow c11 referred to as the “recycled carbon monoxide flow”, comprises both carbon monoxide and carbon dioxide (which is intended for the electrolytic cell) and is joined to the appropriately heated carbon dioxide flow 3 originating the further appropriately heated carbon dioxide flow 3′ to be sent to step A1) described above.

More in particular, said step A2b2) comprises the following steps:

• • p1′) expanding said flow to be regenerated m2 in an expander of the reaction product flow to be regenerated mEK, thus obtaining an expanded flow to be regenerated m3, optionally with the production of power,
  • p2′) heating said expanded reaction product flow to be regenerated m3 in a heat exchanger of the reaction product flow to be regenerated mEX1, thus obtaining an expanded and heated reaction product flow to be regenerated m4, which is sent to a regeneration column CL3,
  • p3′) obtaining a basic aqueous flow m5 from the bottom of said regeneration column CL3 and a carbon dioxide and water flow h1, and obtaining a gaseous flow forming the recirculation gaseous flow cr therefrom.

For the purposes of the present invention, said recirculation gaseous flow cr is joined to the physical solvent-released carbon monoxide flow c8.

A flow can also be obtained from step p3′), which is intended for a reboiler of the third column (vEX1) m8, which must be heated, giving a heated flow exiting from the reboiler m9, which in turn is sent back to the third column CL3.

According to an embodiment of the present invention, such a reboiler vEX1 is inside a Rankine cycle, as described hereinbelow.

For the purposes of the present invention, step A2c) comprises the step of subjecting the mainly carbon monoxide and vapor flow c12 to a dehydration step in a second Dehydration Unit cDU2, thus obtaining a dehydrated carbon monoxide flow c13.

The second Dehydration Unit preferably operates by means of molecular sieves.

For the purposes of the present invention, step A2d) comprises the still further sub-steps of:

• • A2d1) subjecting said dehydrated carbon monoxide flow c13 to a first cooling step, thus obtaining a partially cooled dehydrated carbon monoxide flow c14,
  • A2d2) subjecting said partially cooled dehydrated carbon monoxide flow c14 to a second cooling step, thus obtaining a cooled dehydrated carbon monoxide flow c15,
  • A2d3) subjecting said cooled dehydrated carbon monoxide flow c15 to a third cooling step, thus obtaining a further cooled dehydrated carbon monoxide flow c16,
  • A2d4) expanding said further cooled dehydrated carbon monoxide flow c16 by expansion in a first expander cEK1, possibly with the production of power, thus obtaining an at least partially liquefied carbon monoxide flow c17, which can then be stored in a liquid carbon monoxide tank TCOI.

For the purposes of the present invention, the first cooling step A2d1) is conducted in a first section of a first heat exchanger EX1a.

For the purposes of the present invention, the second cooling step A2d2) is conducted in a second section of a first heat exchanger EX1b.

For the purposes of the present invention, the third cooling step A2d3) is conducted in a third section of a first heat exchanger EX1c.

The heat exchanges of step A2d) are conducted by heat exchange also with a refrigerant circulating in a refrigerant circuit, as will be described hereinafter.

As described above, an initial oxygen flow o1 is also obtained from the electrolysis step A1), from which, in accordance with step A3), an at least partially liquefied oxygen flow o10 is obtained.

For the purposes of the present invention, said step A3) comprises the further sub-steps of:

• • A3a) obtaining a first initial oxygen flow portion o2 and a second initial oxygen flow portion o2′,
  • A3b) cooling said first initial oxygen flow portion o2 in a third heat exchanger EX3a, thus obtaining a first cooled initial oxygen flow portion o3,
  • A3c) cooling said second initial oxygen flow portion o2′ in another third heat exchanger EX3b, thus obtaining a second cooled initial oxygen flow portion o3′,
  • A3d) joining said first cooled initial oxygen flow portion o3 and said second cooled initial oxygen flow portion o3′, thus obtaining a joined cooled oxygen flow o4,
  • A3e) subjecting said joined cooled oxygen flow o4 to compression in an oxygen compressor oC1, thus obtaining a compressed oxygen flow o5 and to cooling in an oxygen exchanger oE, thus obtaining said compressed and cooled oxygen flow o6,
  • A3f) subjecting said compressed and cooled oxygen flow o6 to cooling, thus obtaining an at least partially liquefied oxygen flow o10, which can then be stored in a liquid oxygen tank TO2l.

For the purposes of the present invention, said step A3f) comprises the still further steps of:

• • A3f1) subjecting said compressed and cooled oxygen flow o6 to a first cooling step, thus obtaining an oxygen flow at a further first cooling level o7,
  • A3f2) subjecting said oxygen flow at a further first cooling level o7 to a second cooling step, thus obtaining an oxygen flow at a further second cooling level o8,
  • A3f3) subjecting said oxygen flow at a further second cooling level o8 to a third cooling step, thus obtaining an oxygen flow at a further third cooling level o9,
  • A3f4) expanding said oxygen flow at a further third cooling level o9 to expansion in a first oxygen expander oEK1, possibly with the production of power, thus obtaining an at least partially liquefied oxygen flow o10 stored in a liquid oxygen tank TO2l.

In an embodiment of the present invention, the initial oxygen flow O1 is not separated and is sent entirely to a third exchanger EX3.

For the purposes of the present invention, step A3e) can possibly be repeated if needed until the necessary conditions for the next step A3f) are obtained.

For the purposes of the present invention, the first cooling step A3f1) is conducted in a first section of a first heat exchanger EX1a.

For the purposes of the present invention, the second cooling step A3f2) is conducted in a second section of a first heat exchanger EX1b.

For the purposes of the present invention, the third cooling step A3f3) is conducted in a third section of a first heat exchanger EX1c.

The heat exchanges of steps A3b) and A3c) are also conducted by heat exchange with a refrigerant fluid outside the process, such as air or water.

According to a preferred embodiment, the heat exchanges of steps A3b) and A3c) are conducted by heat exchange with a flow circulating and operating in a Rankine cycle, as will be described hereinafter.

The heat exchanges of step A3f) are also conducted by heat exchange with a refrigerant fluid circulating in a refrigerant fluid cycle, as will be described hereinafter.

According to an aspect of the present invention, said refrigerant fluid can be hydrogen, helium, or nitrogen.

In particular, said refrigerant fluid circuit comprises a first refrigerant fluid flow f1 which is subjected to the steps of:

• • I) cooling, thus obtaining a second refrigerant fluid flow f2,
  • II) further cooling in a first refrigerant fluid exchanger fE1, thus obtaining a third refrigerant fluid flow f3,
  • III) a first heat exchange step with which said third refrigerant fluid flow f3 is cooled, thus obtaining a fourth flow f4,
  • IV) a second heat exchange step with which said fourth refrigerant fluid flow f4 is cooled, thus obtaining a fifth flow f5,
  • V) a third heat exchange step with which said fifth refrigerant fluid flow f5 is cooled, thus obtaining a sixth flow f6,
  • VI) expansion in a first refrigerant fluid expander fEK1, thus obtaining a seventh refrigerant fluid flow f7, possibly with the production of power,
  • VII) a first heat exchange step with which said seventh refrigerant fluid flow f7 is heated, thus obtaining an eighth flow f8,
  • VIII) a second heat exchange step with which said eighth refrigerant fluid flow f8 is heated, thus obtaining a ninth flow f9,
  • IX) a third heat exchange step with which said ninth refrigerant fluid flow f9 is heated, thus obtaining a tenth flow f10,
  • X) compression of said tenth flow f10, thus obtaining an eleventh flow f11 which is cooled in a first refrigerant fluid exchanger fE1, thus obtaining a twelfth flow f12,
  • XI) compression of said twelfth flow f12 by means of a second compression of the refrigerant fluid fC2, thus obtaining the first flow f1.

For the purposes of the present invention, step X) can be repeated one or more times, if needed.

According to an embodiment of the invention, a refrigerant fluid flow portion referred to as a further fourth flow f4′ is obtained from the fourth flow f4, which is expanded in a second refrigerant fluid expander fEK2, thus obtaining a further fifth flow f5′, which is subjected to a heat exchange step VIII*) (similarly to the steps described above), thus obtaining a further sixth flow f6′, which is further heated in a heat exchange step IX*), thus obtaining a further seventh flow f7′, which is then joined to the tenth refrigerant fluid flow f10.

For the purposes of the present invention, cooling step I) is conducted by heat exchange in the second heat exchanger EX2.

For the purposes of the present invention, cooling step III), heating step IX) and heating step IX*) are conducted by heat exchange in the first section of a first heat exchanger EX1a.

For the purposes of the present invention, cooling step IV), step VIII) and step VIII*) are conducted by heat exchange in the second section of a first heat exchanger EX1b.

For the purposes of the present invention, the cooling step V) and the heating step VII) are conducted by heat exchange in the third section of a first heat exchanger EX1c.

As described above, in a particular embodiment of the present invention, step A1) can comprise a step A1′) for producing power by exploiting the heat produced by Joule effect from the electrolytic cell.

More in particular, said step A1′) comprises heating a fluid by heat exchange with the initial carbon monoxide flow c1 or with a portion thereof c2, c2′ and/or by heat exchange with the initial oxygen flow o1 or with a portion o2,o2′ thereof.

After each heating step, the heated fluid is subjected to expansion with production of power.

For the purposes of the present invention, said step A1′) can be a step inside a Rankine cycle.

In an embodiment of the invention, said Rankine cycle is a water vapor cycle.

In a particular embodiment of the present invention, said Rankine cycle comprises subjecting a first vapor flow v1 to the steps of:

• • R1) heating, thus obtaining a second vapor flow v2,
  • R2) expansion of said second vapor flow in a first expander of the Rankine cycle vEK1 with the production of power, thus obtaining a third vapor flow v3,
  • R3) further heating, thus obtaining a fourth vapor flow v4,
  • R4) further expansion in a second expander of the Rankine cycle, thus obtaining a fifth vapor flow v5,
  • R5) cooling in a first exchanger of the Rankine cycle vE1, thus obtaining a sixth condensed vapor flow v6,
  • R6) pumping in a first pump of the Rankine cycle vP1, thus obtaining a seventh condensed vapor flow v7, which is subjected to step
  • R7) further pumping in a second pump of the Rankine cycle vP2, thus obtaining the first vapor flow v1.

For the purposes of the present invention, from the second expander of the Rankine cycle vEK2, a further fifth vapor flow v5′ is further obtained, which is cooled in a particular exchanger of the Rankine cycle vEX1, giving a further sixth vapor flow v6′ (which is in fact a condensed vapor flow), which is further cooled in a second exchanger of the Rankine cycle vE2, thus obtaining a further seventh condensed vapor flow v7′, which is joined to the seventh flow v7 before being sent to the second pump vP2.

For the purposes of the present invention, step R1) is conducted by heat exchange with the second portion of the initial oxygen flow o2′ and with the second portion of the initial carbon monoxide flow c2′ inside the other third heat exchanger EX3b.

For the purposes of the present invention, step R3) is conducted by heat exchange with the first portion of the initial oxygen flow o2 and with the first portion of the initial carbon dioxide/carbon monoxide mixture flow c2 inside the third heat exchanger EX3a.

As for the particular exchanger of the Rankine cycle vEX1, it is the boiler of the third column (vE1): it heats and partially vaporizes m8, as described above.

A particular embodiment of step A2b1) is described below, with which a partially purified carbon monoxide flow c7, a physical solvent-released carbon monoxide flow c8, and a recycled carbon monoxide flow c11 are obtained.

In particular, inside the first column CL1, an initial physical solvent flow s1 encounters the carbon monoxide flow to be purified c6 in countercurrent, thus obtaining the partially purified carbon monoxide flow c7 from the head of the column CL1.

A physical solvent and carbon dioxide flow s2 is obtained from the bottom of the column CL1, comprising an amount of carbon monoxide, which is expanded in a first physical solvent expander sEK1, possibly with the production of power, thus obtaining an expanded physical solvent, carbon monoxide and carbon dioxide flow s3.

The expanded physical solvent, carbon monoxide and carbon dioxide flow s3 releases the carbon monoxide and part of the carbon dioxide inside the solvent separator sS and the solvent column sC by virtue of a regenerated physical solvent washing flow s12; a separate physical solvent flow s7 (liquid) and a main carbon monoxide flow s4 (gaseous) are thus obtained.

Said main carbon monoxide flow 4 is compressed in a first compressed solvent sC1, thus obtaining a main compressed carbon monoxide flow s5, which is cooled in a first solvent exchanger sE1, thus obtaining a main carbon monoxide return flow to the first column s6.

As for the separate physical solvent flow s7, this is expanded in a second solvent expander sEK2, thus obtaining a separate physical solvent flow s8, which is sent to a first separator S1, from which the physical solvent-released carbon monoxide flow c8 described above and a partially regenerated physical solvent flow s9 are obtained.

Said partially regenerated physical solvent flow is pumped by a first solvent pump sP1, thus obtaining a pumped partially regenerated solvent flow s10, which is heated in a first solvent exchanger sE1, thus obtaining a regenerated physical solvent flow at room temperature, of which a first portion s12 is sent to the solvent column sC as regenerated physical solvent and a second portion s13 is pumped by a second solvent pump sP2, thus obtaining the initial physical solvent flow s1.

For the purposes of the present invention, the physical solvent involved in the purification steps in the first column CL1 can be Selexol, Rectisol, Methanol, etc.

A particular embodiment of step A2b2) is described hereinbelow, with which a mainly carbon monoxide and vapor flow c12, a flow to be regenerated m2 and a gaseous recirculation flow cr are obtained.

In particular, inside the second column CL2, the partially purified carbon monoxide flow (which is in gaseous form) obtained from the head of the first column CL1 encounters a basic (liquid) solution flow m1 in countercurrent.

For the purposes of the present invention, a basic solution can be an aqueous solution of an amine, such as methylethylamine (MEA) or a sodium bicarbonate solution.

A reaction product solution flow m2 is thus obtained from the bottom of the second column CL2, which is expanded in an expander of the reaction product flow to be regenerated mEK, thus obtaining an expanded reaction product solution to be regenerated m3, then heated by heat exchange in a basic solution heat exchanger mEX1, thus obtaining an expanded and heated reaction product flow to be regenerated m4.

Said expanded and heated reaction product flow to be regenerated m4 is sent to the regeneration column CL3, from which a basic bottom flow m5 and a head carbon dioxide and water flow h1 are obtained.

As for the basic bottom flow m5, this is cooled by heat exchange inside the basic solution heat exchanger mEX1, thus obtaining a cooled basic bottom flow m6, which is pumped by a basic bottom flow pump mP obtaining a cooled and pumped basic bottom flow m7 and further cooled in a basic solution exchanger mE, thus obtaining the liquid basic solution m1.

The head carbon dioxide and water flow h1 is cooled in a regeneration column exchanger hE, thus obtaining a carbon dioxide and partially condensed water flow h2, from which, inside a regeneration column separator hS, a bottom liquid flow h3 is obtained.

After possibly refilling the bottom liquid flow h3 with a water flow (make-up water in the figures), this is pumped by a regeneration column pump hP, giving a pumped reflux flow h4 of regeneration column sent to the head of the column CL3.

From the separator head of the regeneration column, instead, a gaseous recirculation flow cr is obtained, which is joined to the physical solvent-released carbon monoxide flow c8, as described above.

According to an alternative embodiment of the present invention depicted in FIG. 3, for example, after having obtained an at least partially liquefied carbon monoxide flow c17 with step A2d4), this is subjected to the further steps described below.

In particular, in a first separator cS1, a first liquid bottom flow c18 and a first gaseous head flow c24 are separated from the at least partially liquefied carbon monoxide flow c17.

The first liquid bottom flow c18 is expanded by means of an expansion valve cV, giving a first expanded gaseous bottom flow c19, from which a second liquid bottom flow c20, which is stored in a liquid carbon monoxide tank cTCOI, and a second gaseous head flow c21, are separated in a second separator cS2.

The second gaseous head flow c21 is compressed in a third carbon monoxide compressor cC3 to obtain a second compressed gaseous head flow c22, which is cooled in a third carbon monoxide exchanger cE3 to obtain a second compressed and cooled head flow c23, which is joined to the dehydrated carbon monoxide flow c13.

In particular, the compression and cooling described above can be repeated one or more times, if needed.

As for the first gaseous head flow c24, this is subjected to a heating step A2e), comprising the further sub-steps of:

• • A2e1) first heating, thus obtaining a first gaseous head flow at a first heating level c25,
  • A2e2) second heating, thus obtaining a second gaseous head flow at a first heating level c26,
  • A2e3) third heating, thus obtaining a second gaseous head flow at a third heating level c27, which is joined to the second gaseous head flow c21.

For the purposes of the present invention, step A2e1) is conducted in the third section of the first heat exchanger EX1c.

For the purposes of the present invention, step A2e2) is conducted in the second section of the first heat exchanger EX1b.

For the purposes of the present invention, step A2e3) is conducted in the first section of the first heat exchanger EX1a

According to an alternative embodiment of the present invention, after obtaining an at least partially liquefied oxygen flow o10 with step A3f), this is subjected to the further steps described below.

In particular, a first liquid bottom flow o11 and a first gaseous head flow o17 are separated from the at least partially liquefied oxygen flow o10 in a first separator oS1.

The first liquid bottom flow o11 is expanded by means of an expansion valve oV, giving a first expanded gaseous bottom flow o12, from which a second liquid bottom flow o13, which is stored in a liquid oxygen tank cTO2l, and a second gaseous head flow o14, are separated in a second separator oS2.

The second gaseous head flow o14 is compressed in a second oxygen compressor oC2, thus obtaining a second compressed gaseous head flow o15, which is cooled in a second oxygen exchanger oE2, thus obtaining a second compressed and cooled head flow o16, which is joined to the compressed and cooled oxygen flow o6.

In particular, the compression and cooling described above can be repeated one or more times, if needed.

As for the first gaseous head flow o17, this is subjected to a heating step A3g), comprising the further sub-steps of:

• • A3g1) first heating, thus obtaining a first gaseous head flow at a first heating level o18,
  • A3g2) second heating, thus obtaining a first gaseous head flow at a second heating level o19,
  • A3g3) third heating, thus obtaining a first gaseous head flow at a third heating level o20, which is joined to the second gaseous head flow o14.

For the purposes of the present invention, step A3g1) is conducted in the third section of the first heat exchanger EX1c.

For the purposes of the present invention, step A3g2) is conducted in the second section of the first heat exchanger EX1b.

For the purposes of the present invention, step A3g3) is conducted in the first section of the first heat exchanger EX1a.

In particular, the heat exchanges of step A2e) and A3g) are also conducted by heat exchange with a refrigerant fluid circulating in another refrigerant fluid circuit, as will be described hereinafter.

In particular, said other refrigerant fluid circuit comprises another first refrigerant fluid flow f′1 which is subjected to the steps of:

• • I′) cooling, thus obtaining another second refrigerant fluid flow f′2,
  • II′) further cooling in another first refrigerant fluid exchanger fE1, thus obtaining another third refrigerant fluid flow f′3,
  • III′) a first heat exchange step with which said another third refrigerant fluid flow f′3 is cooled, thus obtaining another fourth flow f′4,
  • IV′) a second heat exchange step with which said another fourth refrigerant fluid flow f4 is cooled, thus obtaining another fifth flow f′5,
  • V′) a third heat exchange step with which said another fifth refrigerant fluid flow f′5 is cooled, thus obtaining another sixth flow f′6,
  • VI′) expansion in another first refrigerant fluid expander fEK1, thus obtaining another seventh refrigerant fluid flow f′7, possibly with the production of power,
  • VII′) a first heat exchange step with which said another seventh refrigerant fluid flow f′7 is heated, thus obtaining another eighth flow f′8,
  • VIII′) a second heat exchange step with which said another eighth refrigerant fluid flow f′8 is heated, thus obtaining another ninth flow f′9,
  • IX′) a third heat exchange step with which said another ninth refrigerant fluid flow f′9 is heated, thus obtaining another tenth flow f′10,
  • X′) compression of said another tenth flow f′10, thus obtaining another eleventh flow f′11 which is cooled in another first refrigerant fluid exchanger fE1 obtaining another twelfth flow f12,
  • XI′) compression of said other twelfth flow f′12 by means of another second compressor of the refrigerant fluid f′C2, thus obtaining said another first flow f′1.

For the purposes of the present invention, step X′) can be repeated one or more times, if needed.

According to an embodiment of the invention, another refrigerant fluid flow portion referred to as another further fourth flow f′4′ is obtained from the another fourth flow f′4, which is expanded in another second refrigerant fluid expander EK2, thus obtaining another further fifth flow f′5′, which is subjected to a heat exchange step VIII*′) (similarly to the step described above), thus obtaining another further sixth flow f′6′, which is further heated in a step IX*′) (similarly to the step described above), thus obtaining another further seventh flow f′7′, which is then joined to the another ninth refrigerant fluid flow f′9′.

For the purposes of the present invention, the cooling step I′) is conducted by heat exchange in the second heat exchanger EX2.

For the purposes of the present invention, the cooling step III′), heating step IX′) and heating step IX*′) are conducted by heat exchange in the first section of a first heat exchanger EX1a.

For the purposes of the present invention, the cooling step IV′) and the heating step VIII′) and the heating step VIII*′) are conducted by heat exchange in the second section of a first heat exchanger EX1b.

For the purposes of the present invention, the cooling step V′) and the heating step VII′) are conducted by heat exchange in the third section of a first heat exchanger EX1c.

In accordance with a second object of the present invention, a method for generating power is described.

For the purposes of the present invention, said generation step B) comprises the sub-steps of:

• • B1) obtaining a combustion gas flow e1 from a gaseous oxygen flow to be sent to the combustor a4 and from a gaseous carbon monoxide flow to be sent to the combustor b4,
  • B2) expanding said combustion gas flow e1 in a combustion gas expander eEK1 with power generation, thus obtaining an expanded combustion gas e2,
  • B3) cooling said combustion gas flow e2 to obtain an expanded and cooled combustion gas flow e3,
  • B4) dehydrating said expanded and cooled combustion gas flow e3 and obtaining a dehydrated combustion gas flow e5,
  • B5) separating a first dehydrated combustion gas flow portion e5′ and obtaining a dehydrated and further cooled combustion gas first flow portion e5″, which is sent to a liquid carbon dioxide tank aTCO2l,
  • B6) cooling the remaining portion of said dehydrated combustion gas flow e5, thus obtaining a dehydrated and cooled combustion gas flow e6, which is in liquid form,
  • B7) pumping said condensed combustion gas flow e6 in a combustion gas pump eP, thus obtaining a condensed and pumped combustion gas flow e7,
  • B8) heating said condensed and pumped combustion gas flow e7, thus obtaining a pumped and heated combustion gas e8, which is sent to the combustor for step B1).

For the purposes of the present invention, said gaseous oxygen flow to be sent to the combustor a4 is obtained from a liquid oxygen flow a1 withdrawn from a liquid oxygen tank aTO2l, which is subjected to the steps:

• • B0a) of pumping by means of a liquid oxygen pump aP, thus obtaining a pumped liquid oxygen flow a2,
  • B0b) subjecting said pumped oxygen flow a2 to a first heating, thus obtaining a partially heated oxygen flow a3,
  • B0c) subjecting said partially heated oxygen flow a3 to a second heating, thus obtaining a vaporized oxygen flow a4, which is sent to a combustor CC for step B1).

For the purposes of the present invention, said gaseous carbon monoxide flow b4 to be sent to the combustor is obtained from a liquid carbon monoxide flow b1 withdrawn from a carbon monoxide tank aTCOl, which is subjected to the steps of:

• • B0′a) pumping by means of a liquid carbon monoxide pump bP, thus obtaining a pumped liquid carbon monoxide flow b2,
  • B0′b) subjecting said pumped carbon monoxide flow b2 to a first heating, thus obtaining a partially heated carbon monoxide flow b3,
  • B0′c) subjecting said partially heated carbon monoxide flow b3 to a second heating, thus obtaining a vaporized carbon monoxide flow b4, which is sent to the combustor CC for step B1).

In particular, said steps B0b) and B0′b) are conducted by heat exchange inside a first oxygen and carbon monoxide heat exchanger eEX1.

In particular, said steps B0c) and B0′c) are conducted by heat exchange inside a second oxygen and carbon monoxide heat exchanger eEX2.

For the purposes of the present invention, a dehydrated and cooled combustion gas flow portion e6′ is separated from the dehydrated and cooled combustion gas flow e6 obtained from step B6), which is sent to the liquid carbon dioxide tank aTCO2l.

For the purposes of the present invention, step B4) comprises the further sub-steps of: B4a) separating a first water portion eW1 in a combustion gas separator eS, thus obtaining a partially dehydrated combustion gas flow e4,

• • B4b) dehydrating the partially dehydrated combustion gas flow e4 in a combustion gas Dehydration Unit eDU, thus obtaining the dehydrated combustion gas flow e5.

For the purposes of the present invention, the cooling step B5) is conducted by heat exchange inside the first oxygen and carbon monoxide heat exchanger eEX1.

For the purposes of the present invention, steps B3) and B8) described above are conducted by heat exchange inside the second oxygen and carbon monoxide heat exchanger eEX2.

As for step B6), this is conducted in a refrigerant fluid heat exchanger EXfr.

In particular, a first refrigerant fluid flow arf1 is withdrawn from a refrigerant fluid tank aTrf1, which is heated by heat exchange with the dehydrated combustion gas flow e5, thus obtaining a second cooled fluid flow arf2, which is stored in a second refrigerant fluid tank aTrf2.

For the purposes of the present invention, the refrigerant fluid employed in step B6) is a storage refrigerant fluid, which can be glycol or an aqueous glycol solution.

According to a particular embodiment of the present invention, an additional flow F consisting of carbon dioxide and hydrocarbons, for example methane, or consisting of carbon monoxide produced, for example, by the gasification of coal or as a refinery residue, can further be sent to step B1).

According to an alternative embodiment of the present invention, for example shown in FIG. 5, in step B2) the combustion gas flow e1) is expanded in a two-stage expansion machine; thereby, a first expanded combustion flow portion e2 is obtained, which is then subjected to the further steps described above.

From the second expansion stage, a fully expanded combustion gas flow e12 (referred to as the second expanded combustion gas flow) is instead obtained, which is subjected to the further steps of:

• • B9) cooling, thus obtaining a second cooled expanded combustion gas flow e13,
  • B10) cooling in a fourth heat exchanger EX4, thus obtaining a second further-cooled expanded combustion gas flow e14,
  • B11) separating a second water portion eW2, thus obtaining a second dehydrated combustion gas flow e15,
  • B12) compressing said second dehydrated combustion gas flow e15 in a combustion gas compressor, thus obtaining a second compressed combustion gas flow e16,
  • B13) heating the second compressed combustion gas flow e16, thus obtaining a second compressed and heated combustion gas flow e17,
  • B14) further heating the second compressed and heated combustion gas flow e17, thus obtaining a second compressed and further-heated combustion gas flow e18.

For the purposes of the present invention, steps B9) and B13) are both conducted in a third heat exchanger EX3 by heat exchange between the fully expanded combustion gas flow e12 and the second compressed combustion gas flow e16 in countercurrent.

As for step B10), this is instead conducted inside a fourth heat exchanger EX4, described below.

For the purposes of the present invention, from the condensed and pumped combustion gas flow e7 obtained from step B7) a portion e9 (to be referred to as the second condensed and pumped combustion gas flow) is separated, which is subjected to the further steps of:

• • B15) heating, thus obtaining a second condensed and pumped heated combustion gas flow e10,
  • B16) further heating, thus obtaining a second condensed and pumped further-heated combustion gas flow e11.

For the purposes of the present invention, step B15) is conducted in the fourth heat exchanger EX4 by heat exchange with the cooled expanded combustion gas flow e13.

For the purposes of the present invention, step B16) is conducted in the second heat exchanger eEX2.

According to the present embodiment, the three flows represented by:

• • pumped and heated combustion gas flow e8,
  • second further-heated condensed and pumped combustion gas flow e11 and
  • compressed and further-heated combustion gas flow e18
  • are joined in a single flow e19 which is returned to the combustor for step B1).

For the purposes of the present invention, the flows of liquid carbon monoxide b1 and liquid oxygen a1 employed in the generation step (step B)) are obtained from tanks aTCOI, aTO2I in which a flow of liquid carbon monoxide c20 and a flow of liquid oxygen o13 obtained according to the method of the accumulation step A) of the present invention and indicated above by cTCOI and cTO2I, respectively, are stored.

In accordance with another object, the present invention describes a method for producing and accumulating energy, producing carbon monoxide and ultra-pure oxygen, as well as for using carbon dioxide and producing liquid carbon dioxide.

In a particular aspect, the method of the invention allows the management of energy peaks and deficiencies (peak shaving).

Therefore, the present invention globally describes the following points:

Point 1: A method for producing and accumulating energy, producing carbon monoxide and oxygen, and using carbon dioxide, comprising an accumulation step A) and a generation step B), where said accumulation step A) allows producing a carbon monoxide flow (CO) and an oxygen flow and possibly a refrigerated fluid.

Point 2: The method according to the preceding point, where said step A) comprises the sub-steps of:

• • A1) electrolyzing an appropriately-heated carbon dioxide flow 3 and obtaining an initial carbon monoxide flow c1 and an initial oxygen flow o1,
  • A2) obtaining an at least partially liquefied carbon monoxide flow c17 from the initial carbon monoxide flow c1,
  • A3) obtaining an at least partially liquefied oxygen flow o10 from the initial oxygen flow o1.

Point 3: The method according to the preceding point, where said step A2) comprises the further sub-steps of:

• • A2a) obtaining a carbon monoxide flow to be purified c6,
  • A2b) obtaining a mainly carbon monoxide and vapor flow c12, a recycled carbon monoxide flow c11, and a recirculation gas flow cr,
  • A2c) obtaining a dehydrated carbon monoxide flow c13,
  • A2d) obtaining an at least partially liquefied carbon monoxide flow c17.

Point 4: The method according to the preceding point, where said step A2a) comprises the further sub-steps of:

• • A2a1) obtaining a first initial carbon monoxide flow portion c2 and a second initial carbon monoxide flow portion c2′,
  • A2a2) cooling said first initial carbon monoxide flow portion c2 in a third heat exchanger EX3a, thus obtaining a first cooled initial carbon monoxide flow portion c3,
  • A2a3) cooling said second initial carbon monoxide flow portion c2′ in another third heat exchanger EX3b, thus obtaining a second cooled initial carbon monoxide flow portion c3′,
  • A2a4) joining said first cooled initial carbon monoxide flow portion c3 and said second cooled initial carbon monoxide flow portion c3′, thus obtaining a joined cooled carbon monoxide flow c4,
  • A2a5) subjecting said joined cooled carbon monoxide flow c4 to compression in a first compressor cC1, thus obtaining a compressed carbon monoxide flow c5, and to cooling in a first exchanger cE1, thus obtaining said carbon monoxide flow to be purified c6.

Point 5: The method according to the preceding point, where the heat exchanges of steps A2a2) and A2a3) are conducted by heat exchange with a flow circulating and operating in a Rankine cycle.

Point 6: The method according to the preceding point, where said sub-step A2b) comprises the still further sub-steps of:

• • A2b1) subjecting the carbon monoxide flow to be purified c6 to a first purification in a first purification column CL1 and obtaining a partially purified carbon monoxide flow c7, a physical solvent-released carbon monoxide flow c8, and a recycled carbon monoxide flow c11,
  • A2b2) subjecting the partially purified carbon monoxide flow c7 to a second purification in a second purification column CL2, thus obtaining a mainly carbon monoxide and vapor flow c12, a flow to be regenerated m2, and a recirculation gas flow cr.

Point 7: The method according to the preceding point, where said sub-step A2b1) comprises the following steps:

• • p1) washing with a physical solvent,
  • p2) separation from the physical solvent, thus obtaining a regenerated physical solvent flow s9 and a physical solvent-separated flow c8,
  • p3) compression and cooling, thus obtaining a physical solvent-separated compressed flow c9 and cooled c10,
  • p4) dehydration in a first Dehydration Unit cDU1, thus obtaining the recycled carbon monoxide flow c11.

Point 8: The method according to the preceding point, where said recycled carbon monoxide flow c11 is joined to the appropriately-heated carbon monoxide flow 3, originating the further appropriately-heated carbon monoxide flow 3′ to be sent to step A1).

Point 9: The method according to point 6, where said step A2b2) comprises the following steps:

• • p1′) expanding said flow to be regenerated m2 in an expander of the reaction product flow to be regenerated mEK, thus obtaining an expanded flow to be regenerated m3, optionally with the production of power,
  • p2′) heating said expanded reaction product flow to be regenerated m3 in a heat exchanger of the reaction product flow to be regenerated mEX1, thus obtaining an expanded and heated reaction product flow to be regenerated m4, which is sent to a regeneration column CL3,
  • p3′) obtaining a basic aqueous flow m5 from the bottom of said regeneration column CL3 and a carbon dioxide and water flow h1 from the head, and obtaining a gaseous flow forming the recirculation gaseous flow cr therefrom.

Point 10: The method according to the preceding point, where said recirculation gas flow cr is joined to the physical solvent-released carbon monoxide flow c8.

Point 11: The method according to point 9, where a flow can also be obtained from said step p3′), which is intended for a reboiler of the third column (vEX1) m8, which is heated, giving rise to a heated flow exiting from the reboiler m9, which in turn is sent back to the regeneration column CL3.

Point 12: The method according to point 3, where said step A2d) comprises the still further sub-steps of:

• • A2d1) subjecting said dehydrated carbon monoxide flow c13 to a first cooling step, thus obtaining a partially cooled dehydrated carbon monoxide flow c14,
  • A2d2) subjecting said partially cooled dehydrated carbon monoxide flow c14 to a second cooling step, thus obtaining a cooled dehydrated carbon monoxide flow c15,
  • A2d3) subjecting said cooled dehydrated carbon monoxide flow c15 to a third cooling step, thus obtaining a further cooled dehydrated carbon monoxide flow c16,
  • A2d4) expanding said further cooled dehydrated carbon monoxide flow c16 by expansion in a first expander cEK1, possibly with the production of power, thus obtaining an at least partially liquefied carbon monoxide flow c17, which can then be stored in a liquid carbon monoxide tank TCOI.

Point 13: The method according to point 3, where the heat exchanges of step A2d) are conducted by heat exchange also with a refrigerant circulating in a refrigerant circuit.

Point 14: The method according to point 2, where said step A3) comprises the further sub-steps of:

• • A3a) obtaining a first initial oxygen flow portion o2 and a second initial oxygen flow portion o2′,
  • A3b) cooling said first initial oxygen flow portion o2 in a third heat exchanger EX3a, thus obtaining a first cooled initial oxygen flow portion o3,
  • A3c) cooling said second initial oxygen flow portion o2′ in another third heat exchanger EX3b, thus obtaining a second cooled initial oxygen flow portion o3′,
  • A3d) joining said first cooled initial oxygen flow portion o3 and said second cooled initial oxygen flow portion o3′, thus obtaining a joined cooled oxygen flow o4,
  • A3e) subjecting said joined cooled oxygen flow o4 to compression in an oxygen compressor oC1, thus obtaining a compressed oxygen flow o5 and to cooling in an oxygen exchanger oE1, thus obtaining said compressed and cooled oxygen flow o6,
  • A3f) subjecting said compressed and cooled oxygen flow o6 to cooling, thus obtaining an at least partially liquefied oxygen flow o10, which can then be stored in a liquid oxygen tank TO2l.

Point 15: The method according to the preceding point, where the heat exchanges of steps A3b) and A3c) are conducted by heat exchange with a flow circulating and operating in a Rankine cycle.

Point 16: The method according to the preceding point, where the heat exchanges of step A3f) are conducted by heat exchange also with a refrigerant fluid circulating in a refrigerant fluid cycle.

Point 17: The method according to the preceding step, where said refrigerant fluid is hydrogen, helium, or nitrogen.

Point 18: The method according to point 9, where said gaseous recirculation flow cr is joined to the physical solvent-released carbon monoxide flow c8.

Point 19: The method according to any one of the preceding points, where said step A) is conducted by using excess electric current available in the network.

Point 20: The method according to any one of the preceding points, where said generating step B) comprises the sub-steps of:

• • B1) obtaining a combustion gas flow e1 from a gaseous oxygen flow a4 sent to the combustor and from a gaseous carbon monoxide flow b4 sent to the combustor,
  • B2) expanding said combustion gas flow e1 in a combustion gas expander eEK1 with power generation, thus obtaining an expanded combustion gas e2,
  • B3) cooling said combustion gas flow e2 to obtain an expanded and cooled combustion gas flow e3,
  • B4) dehydrating said expanded and cooled combustion gas flow e3 and obtaining a dehydrated combustion gas flow e5,
  • B5) separating a first dehydrated combustion gas flow portion e5′ and obtaining a dehydrated and further cooled combustion gas first flow portion e5″, which is sent to a liquid carbon dioxide tank aTCO2l,
  • B6) cooling the remaining portion of said dehydrated combustion gas flow e5, thus obtaining a dehydrated and cooled combustion gas flow e6, which is in liquid form,
  • B7) pumping said condensed combustion gas flow e6 in a combustion gas pump eP, thus obtaining a condensed and pumped combustion gas flow e7,
  • B8) heating said condensed and pumped combustion gas flow e7, thus obtaining a pumped and heated combustion gas e8, which is sent to the combustor for step B1).

Point 21: The method according to the preceding point, where in said step B6) a portion of the dehydrated and cooled combustion gas flow e6′ is separated, which is sent to the liquid carbon dioxide tank aTCO2l.

Point 22: The method according to point 20 or 21, where step B4) comprises the further sub-steps of:

• • B4a) separating a first water portion eW1 in a combustion gas separator eS1, thus obtaining a partially dehydrated combustion gas flow e4,
  • B4b) dehydrating the partially dehydrated combustion gas flow e4 in a combustion gas Dehydration Unit eDU, thus obtaining the dehydrated combustion gas flow e5.

Point 23: The method according to the preceding point, where said cooling step B5) is conducted by heat exchange inside the first oxygen and carbon monoxide heat exchanger eEX1.

Point 24: The method according to any one of points 20 to 23, where said steps B3) and B8) are conducted by heat exchange inside the second oxygen and carbon monoxide heat exchanger eEX2.

Point 25: The method according to the preceding point, where said step B6) is conducted in a refrigerant fluid heat exchanger EXfr.

Point 26: The method according to any one of points 20 to 25, where in step B1) an additional flow F consisting of carbon dioxide and hydrocarbons can further be sent.

Point 27: The method according to any one of points 20 to 26, where in step B2) the combustion gas flow e1) is expanded in one or two expansion stages, thus obtaining a first expanded combustion gas flow portion e2 and possibly also a fully expanded combustion gas flow e12, which is subjected to the further steps of:

• • B9) cooling, thus obtaining a second cooled expanded combustion gas flow e13,
  • B10) cooling, thus obtaining a second further-cooled expanded combustion gas flow e14,
  • B11) separating a second water portion eW2, thus obtaining a second dehydrated combustion gas flow e15,
  • B12) compressing said second dehydrated combustion gas flow e15 in a combustion gas compressor eC, thus obtaining a second compressed combustion gas flow e16,
  • B13) heating the second compressed combustion gas flow e16, thus obtaining a second compressed and heated combustion gas flow e17,
  • B14) further heating the second compressed and heated combustion gas flow e17, thus obtaining a second compressed and further-heated combustion gas flow e18.

Point 28: The method according to the preceding point, where said steps B9) and B13) are conducted in a third heat exchanger EX3 by heat exchange between the fully expanded combustion gas flow e12 and the second compressed combustion gas flow e16 in countercurrent.

Point 29: The method according to point 27 or 28, where said step B10) is conducted inside a fourth heat exchanger EX4.

Point 30: The method according to point 20, where a portion e9 is separated from the condensed and pumped combustion gas flow e7 obtained from step B7), which is subjected to the further steps of:

• • B15) heating, thus obtaining a second condensed and pumped heated combustion gas flow e10,
  • B16) further heating, thus obtaining a second condensed and pumped further-heated combustion gas flow e11.

Point 31: The method according to the preceding point, where said step B15) is conducted in the fourth heat exchanger EX4 by heat exchange with the cooled expanded combustion gas flow e13.

Point 32: The method according to the preceding point, where said step B16) is conducted in the second heat exchanger eEX2.

Point 33: The method according to any one of the preceding points 20 to 32, where the three flows represented by:

• • pumped and heated combustion gas flow e8,
  • second further-heated condensed and pumped combustion gas flow e11 and
  • compressed and further-heated combustion gas flow e18
  • are joined in a single flow e19 which is returned to the combustor for step B1).

From the above description, the advantages offered by the present invention will be immediately apparent to those skilled in the art.

In particular, the method described solves most of the known technical problems inherent in oxy-combustion processes, such as the need to provide amounts of high-purity oxygen, for example by means of ASU technologies.

Moreover, the oxy-combustion cycle described combines a Brayton cycle and a Rankine cycle using carbon dioxide as a driving fluid, possibly in the presence of small amounts of water (<20% mol/mol), more efficient by virtue of the possibility to operate at higher temperatures.

For example, FIG. 1 shows a thermodynamic cycle comprising a Rankine cycle and a Brayton cycle, where the relative contributions are optimized to introduce heat at the highest temperature compatible with the technological constraints of the machines and reject heat at the lowest temperature compatible with the availability of a thermal well.

The system also operates with great efficiency by virtue of the high energy density of liquid carbon monoxide and oxygen.

The method of the present invention globally allows the so-called peak shaving, because it allows stabilizing the electrical network by absorbing available excess electricity and storing it in the form of liquid gases, in particular carbon monoxide and oxygen, to be subjected to oxy-combustion to produce energy in periods of shortage, while accumulating liquid carbon dioxide.

Note that the carbon monoxide obtained also is a useful chemical intermediate, which can thus be marketed.

Last but not least, the method of the invention actually is a system for using carbon dioxide, produced by industrial or refinery processes or even environmental processes, which is thus subtracted and/or not released into the atmosphere.

Therefore, the method can allow the exploitation of deposits which have a high carbon dioxide content.

For the avoidance of doubt, the method removes carbon dioxide and produces no more.

In the embodiment which does not include vapor and condensates, it is particularly suitable for off-shore applications.