thermal installation

Abstract

The invention relates to a thermal installation (1) equipped with an oxy-combustion boiler comprising: - an oxy-burner (10); - a first condenser (50) for collecting a first fraction of the combustion gases at the exhaust outlet (12), the first condenser (50) being configured to condense the water contained in this first fraction so that said first fraction forms, at the outlet of the first condenser (50), a first enriched fraction comprising mainly carbon dioxide; - a heat exchanger (60) configured to allow heat exchange between the first enriched fraction and an oxidant before its injection into the oxy-burner (10), said heat exchange leading to an increase in the temperature of the oxidant and a decrease in the temperature of the first enriched fraction; - a means for storing the first enriched fraction. Figure 1

Description

Description Title of the invention: Thermal installation FIELD OF THE INVENTION The present invention relates to the field of thermal energy and more particularly to the field of boilers. In particular, the present invention concerns a thermal installation equipped with an energy-optimized oxy-combustion boiler with limited greenhouse gas emissions. TECHNOLOGICAL BACKGROUND OF THE INVENTION A boiler equipped with an oxy-burner (hereinafter "oxy-combustion boiler") generally uses pure oxygen as an oxidant so that the fumes from the combustion are essentially free of nitrogen and / or sulfur compounds. However, for reasons of convenience, the pure oxygen feeding the boiler can be in liquid form, and therefore needs to be heated in order to be injected into the oxy-burner in gaseous form. This last aspect therefore implies an energy input which limits the overall efficiency of the installation equipped with an oxy-combustion boiler. One aim of the present invention is therefore to propose an installation equipped with an oxy-combustion boiler which makes it possible to utilize the cooling provided by liquid oxygen in order to improve the overall efficiency of the installation. Another objective of the present invention is to provide a thermal installation equipped with an oxy-combustion boiler which allows for the efficient recovery of carbon dioxide from combustion. BRIEF DESCRIPTION OF THE INVENTION The goals of the invention are, at least in part, achieved by a thermal installation which includes an oxy-combustion boiler, said boiler comprising an oxy-burner provided with an injection inlet and an exhaust outlet and through which gases, called combustion gases and comprising carbon dioxide and water, are capable of being evacuated. The heating system also includes: - a first condenser intended to collect a first fraction of the combustion gases at the exhaust outlet, the first condenser being configured to condense the water contained in this first fraction so that said first fraction forms, at the outlet of the first condenser, a first enriched fraction comprising mainly carbon dioxide; - a heat exchanger configured to allow heat exchange between the first enriched fraction and an oxidant before its injection into the oxy-burner, said heat exchange leading to an increase in the temperature of the oxidant and a decrease in the temperature of the first enriched fraction; - a means of storing the first enriched fraction in liquid form. According to one implementation method, the heat exchanger is also configured to allow liquefaction of the first enriched fraction. According to one embodiment, said boiler includes recirculation means configured to take a second fraction of the combustion gases and mix them with the oxidizer before or after its injection at the injection inlet. According to one implementation method, vaporization means are configured to vaporize an oxidant, initially present in liquid form, before its injection into the oxy-burner through the injection inlet during a boiler start-up phase. According to one implementation method, a compressor is interposed between the first condenser and the heat exchanger, said compressor is configured to compress the first enriched fraction. According to one embodiment, said installation also includes a second condenser interposed between the compressor and the heat exchanger, said second condenser being configured to condense, at least in part, the water likely to be present in the first enriched fraction. According to one implementation method, said installation includes an oxidant source, said oxidant comprising liquid oxygen. According to one implementation method, the oxidant source is configured to produce liquid oxygen. According to one implementation method, the oxidizer source includes a reservoir. According to one embodiment, the heat exchanger is configured to allow the recovery of the first enriched non-condensed fraction, and to inject this part at the injection inlet. Brief description of the drawings Other features and advantages of the invention will become apparent from the detailed description that follows, with reference to the attached figure in which: |Fig.1] Fig.1] is a schematic representation of a thermal installation conforming to the principles of the present invention. DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal installation equipped with a boiler oxycombustion which allows both the recovery of the cooling provided by liquid oxygen and the recovery of the "hot fumes" resulting from the combustion of a combustible gas in the presence of essentially pure dioxygen as an oxidizer. In particular, the present invention implements heat exchange means for condensing carbon dioxide. Furthermore, the present invention also aims at the purification and / or sequestration and / or storage of carbon dioxide from combustion in the oxy-burner in order to limit its emissions into the atmosphere and where appropriate to valorize it. Thus, the invention relates to a thermal installation equipped with an oxy-combustion boiler which includes an oxy-burner equipped with an injection inlet and an exhaust outlet and through which gases, called combustion gases and comprising carbon dioxide and water, are capable of being evacuated; The installation also includes: - a first condenser intended to collect a first fraction of the combustion gases at the exhaust outlet, the first condenser being configured to condense the water contained in this first fraction so that said first fraction forms, at the outlet of the first condenser, a first enriched fraction comprising mainly carbon dioxide; - a heat exchanger configured to allow heat exchange between the first enriched fraction and an oxidant before its injection into the oxy-burner, said heat exchange leading to an increase in the temperature of the oxidant and a decrease in the temperature of the first enriched fraction; - a means of storing the first enriched fraction in liquid form. In [Fig.1], we can see a schematic diagram of the operating principle of a thermal installation 1 equipped with an oxy-combustion boiler la according to the terms of the present invention. In particular, the oxy-combustion boiler includes an oxy-burner 10. According to the terms of the present invention, an oxy-burner is a burner adapted for the combustion of a fuel in the presence of an oxygen-rich oxidant. In this regard, it will be considered throughout this statement that an oxygen-rich oxidant comprises at least 85% oxygen, advantageously at least 95% oxygen, even more advantageously at least 98% oxygen, for example, above 99%. It is understood that the oxygen contents are given as a volume percentage. The oxy-combustion boiler also includes a heat exchange chamber 20 coupled to the oxy-burner 10, in which the combustion of the combustible in the presence of an oxidizer. In particular, the heat exchange chamber 20 is the site of heat exchange where the thermal energy produced by the oxy-burner 10, during fuel combustion, is at least partially transferred to a fluid. This fluid, for example water, flows from an inlet, called the cold inlet, to an outlet, called the hot outlet. The oxy-burner 10 includes an inlet called the injection inlet 11, while the heat exchange chamber includes an outlet, called the exhaust outlet 12. More specifically, the injection inlet 11 is an inlet through which the oxidant is intended to be injected preferentially in gaseous form, while the exhaust outlet is an outlet through which the combustion gases are likely to be evacuated. In particular, the combustion gases result from the combustion of a fuel, also injected into the oxy-burner 10. In this regard, the fuel may include natural gas (gas consisting essentially of methane), and be injected at a second injection inlet 13 of the oxy-burner 10. The thermal installation may also include a 30-liter liquid oxygen reserve. Specifically, this 30-liter reserve may include an oxygen storage tank and / or a station configured for the production and storage of oxygen. The thermal installation | may also include means for vaporizing 40 dioxygen. In particular, these vaporization means 40 are configured to take liquid dioxygen from the reservoir 30, and after vaporization, distribute the gaseous dioxygen at the injection inlet 11. In other words, the vaporization means 30 are intercalated between the reservoir 30 and the injection inlet 11. Vaporization means 40 are advantageously implemented during a start-up phase of the oxy-combustion boiler. The present invention also provides for a recirculation of the combustion gases (products of the combustion of the oxidant and the fuel), towards a heat exchanger in which the liquid oxidant is heated by heat exchange. Thus, the thermal installation includes a first condenser 50. In particular, the first condenser 50 is intended to take a first fraction of the combustion gases at the exhaust outlet and to condense the water contained in this first fraction so that said first fraction forms, at the outlet of the first condenser 50, a first enriched fraction comprising mainly carbon dioxide. By "composed mainly of carbon dioxide", we mean a content, in volume percentage, greater than 80%, advantageously greater than 90%, even more advantageously greater than 95%. Generally, a condenser operates with a cooling circuit, notably through heat exchange with a heat transfer fluid. During this heat exchange, the temperature of the first gas fraction decreases to a temperature lower than the condensation temperature of water, causing the water to condense into liquid water and thus depleting the first fraction of water. The heat transfer fluid may include water, but the invention is not limited to this aspect alone. The temperature of the first fraction exiting the oxy-combustion boiler can be between 100°C and 200°C. At the outlet of the first condenser 50, the temperature of the first enriched fraction can be between 20°C and 50°C, and for example be equal to 25°C. Thermal installation 1 also includes a heat exchanger 60. The heat exchanger 60 is specifically configured to allow heat exchange between the first enriched fraction and the oxidant before its injection into the oxy-burner 10. In particular, the heat exchanger 60 includes means for the circulation of an inlet to an outlet of the oxidant, and other means for the circulation of another inlet to another outlet of the first enriched fraction. More specifically, the oxidant enters through the inlet of the heat exchanger at a given temperature, and possibly in liquid form, and exits through the outlet, at a higher temperature and in gaseous form. Similarly, the first enriched fraction enters the heat exchanger at a given temperature, for example equal to 40 °C, and exits, through the other outlet, at a lower temperature, for example below -20 °C. Particularly advantageously, the first enriched fraction can exit through the other outlet in condensed form, in other words, liquid. In this respect, the heat exchanger 60 may include a temperature swing absorber (or "temperature swing absorber" in Anglo-Saxon terminology) which allows the first enriched fraction to be dewatered. Advantageously, the temperature swing absorber is located upstream of the other inlet of the heat exchanger (the other inlet being the inlet through which the first enriched fraction enters the heat exchanger). In this respect, the heat exchanger 60 can be combined with a chiller 70, thus giving the assembly formed by the heat exchanger 60 and the chiller a liquefier function. Specifically, this assembly can be configured to allow the storage of carbon dioxide, in liquid form, at a temperature below -17°C and at a pressure below 22 bar. This arrangement is particularly advantageous as it allows the first enriched fraction (i.e., carbon dioxide) to be liquefied, thus paving the way for its storage and, if necessary, its transport. According to this arrangement, the oxidant, in condensed form, at the inlet of the heat exchanger provides some of the cooling energy required for the cooling, and where applicable, the liquefaction of the first enriched fraction. This latter aspect allows for a chiller unit with moderate power output. More specifically, the chiller unit considered within the framework of the present invention may have a lower power output than a chiller unit for a heat exchanger lacking heat exchange means with the oxidant. In addition, the thermal installation | is advantageously equipped with a storage means 80 allowing the first enriched fraction to be stored in liquid form. The heat exchanger 60 can also be configured to recover some of the uncondensed gases for injection at the injection inlet 11. These uncondensed gases may contain oxygen not used during fuel combustion. Their recovery thus reduces the oxygen consumption required for the operation of the oxy-burner 10. The thermal installation | may also include a compressor 90 interposed between the first condenser 50 and the heat exchanger 60, said compressor 90 is configured to compress the first enriched fraction before it is injected into the heat exchanger 60. In particular, the 90 compressor is configured to compress the first enriched fraction in a pressure range between 20 bar and 30 bar, for example to a pressure of 27 bar. Advantageously, the thermal installation also includes a second condenser 100 interposed between the compressor 90 and the heat exchanger 60, said second condenser 100 being configured to condense, at least partially, the water that may be present in the first enriched fraction. This second condenser increases the proportion of carbon dioxide in said first enriched fraction, and consequently facilitates its liquefaction in the heat exchanger 60. Finally, the thermal installation 1 may include recirculation means configured to take a second fraction of the combustion gases and mix them with the oxidizer before or after its injection at the injection inlet 11. The second fraction may in particular represent at least 50%, advantageously at least 60%, even more advantageously at least 70% of the combustion gases. This last aspect helps to limit the flame temperature in the oxy-burner and thus avoiding damage to the materials forming it. Thermal installation 1 limits the electricity consumption associated with the carbon dioxide compression and cooling stages. Furthermore, the oxy-combustion boiler described herein also limits carbon dioxide emissions and stores it in liquid form, advantageously at a purity level that allows for its use in industry. Finally, the water discharged by the first condenser and the second condenser can be advantageously utilized. Of course, the invention is not limited to the embodiments described and alternative embodiments can be made without departing from the scope of the invention as defined by the claims.

Claims

Claims

1. Thermal installation (1) which comprises an oxycombustion boiler (1a), said boiler comprising an oxy-burner (10) provided with an injection inlet (11) and an evacuation outlet (12) and through which gases, called combustion gases and comprising carbon dioxide and water, are capable of being evacuated; the thermal installation further comprises: - a first condenser (50) intended to collect a first fraction of the combustion gases at the evacuation outlet (12), the first condenser (50) being configured to condense the water contained in this first fraction so that said first fraction forms, at the outlet of the first condenser (50), a first enriched fraction comprising mainly carbon dioxide;- a heat exchanger (60) configured to allow a heat exchange between the first enriched fraction and an oxidant before its injection into the oxy-burner (10), said heat exchange leading to an increase in the temperature of the oxidant and a decrease in the temperature of the first enriched fraction; - a means allowing the storage of the first enriched fraction in liquid form; the heat exchanger (60) is configured to allow the recovery of the non-condensed first enriched fraction part, and to inject this part at the injection inlet (11).;

2. Thermal installation (1) according to claim 1, in which the heat exchanger (60) is also configured to allow liquefaction of the first enriched fraction.

3. Installation according to claim 1 or 2, in which said boiler comprises recirculation means configured to take a second fraction of the combustion gases and mix them with the oxidant before or after its injection at the injection inlet (H).

4. Installation according to one of claims 1 to 3, in which vaporization means (40) are configured to vaporize an oxidizer, initially present in liquid form, before its injection into the oxy-burner (10) via the injection inlet (11) during a start-up phase of the boiler.

5. Installation according to one of claims 1 to 4, in which a com- presser (90) is interposed between the first condenser (50) and the heat exchanger (60), said compressor (90) is configured to compress the first enriched fraction.

6. Installation according to claim 5, in which said installation also comprises a second condenser (100) interposed between the compressor (90) and the heat exchanger (60), said second condenser (100) being configured to condense, at least in part, the water likely to be present in the first enriched fraction.

7. Installation according to one of claims 1 to 7, in which said installation comprises a source of oxidant, said oxidant comprising liquid oxygen.

8. Installation according to claim 7, in which the source of oxidant is configured to produce liquid oxygen.

9. Installation according to claim 7, in which the source of oxidant comprises a reservoir (30).

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