FR3137160A1 - INSTALLATION FOR TREATING A GASEOUS HYDROGEN FLOW BY STAGED CATALITIC COMBUSTION - Google Patents

Abstract

INSTALLATION FOR TREATING A GAS FLOW OF HYDROGEN BY STAGED CATALITIC COMBUSTION Installation (14) for treating a gas flow (16) comprising successive stages (26, 28, 30) adapted to burn hydrogen from the gas flow, each of stages (26, 28, 30) comprising: - a source (38, 40, 42) of a gaseous oxidant flow, - a catalytic burner (50, 52, 54) adapted to admit an inlet flow (56, 58, 60), the oxidant flow, and to produce a flow of smoke (62, 64, 66), - an exchanger (68, 70, 72) to cool the flow of smoke and obtain an outlet flow (74, 76, 78). The inlet flow of a first stage comprises the gas flow to be treated, the inlet flow of each of the other stages comprising the outlet flow of the previous stage. In all stages, except the last, the catalytic burner burns only a fraction of the hydrogen present in the inlet flow, the outlet flow still including hydrogen. The installation produces at least one flow of water (18) from the outlet flow of at least one of the stages. Figure for abstract: Figure 2

Description

INSTALLATION FOR TREATING A GASEOUS HYDROGEN FLOW BY STAGED CATALITIC COMBUSTION

The present invention relates to an installation adapted to eliminate by combustion a gas stream to be treated comprising at least 75% hydrogen by volume.

The invention also relates to a naval platform, in particular an underwater vehicle, comprising such an installation.

The invention also relates to a treatment method implementing such an installation.

The gas flow to be treated is, for example, pure hydrogen from the operation of a fuel cell on board a naval platform, or produced by a chemical reaction.

By “elimination”, we mean the transformation, preferably total, of hydrogen into one or more products that can be stored in the naval platform or released into its environment.

Currently, to achieve this elimination of hydrogen, it is known to use a catalytic burner supplied with ventilation air. Such a solution is used to treat releases of diluted hydrogen from batteries or a propulsion system, in order to maintain a hydrogen concentration below the lower explosive limit in the naval platform. However, this solution is not suitable for treating a gas with a high hydrogen content. There is a risk of reaching a high temperature in the burner catalyst, which can cause damage to the equipment, a fire or an explosion in the event of a hydrogen concentration higher than the lower explosive limit at the burner inlet. This technology is therefore not sufficiently safe to be used in a naval platform such as an underwater vehicle.

To achieve this elimination, it would be possible to use a fuel cell and produce electricity from the hydrogen to be eliminated and oxygen. This solution may seem interesting from the point of view of space requirements, but it must be navalized and adapted to reduce risks in order to allow its approval. However, the approval constraints are higher for such equipment than for a fuel cell used for propulsion. Such a solution is therefore not currently considered sufficiently reliable in the particularly restrictive environment of an underwater vehicle, including in exceptional environmental situations and after an impact.

To achieve the elimination of hydrogen, a mechanical compressor similar to those used to treat carbon dioxide emissions could be used. However, this type of compressor cannot be used as is with hydrogen. The external sealing of this type of material is often weak. Furthermore, the reliability of this type of component does not appear sufficient to ensure safe operation. In addition, this technology does not appear appropriate from the point of view of acoustic and vibration discretion. It could also pose a congestion problem.

There are also metal hydride compressors for removing hydrogen on a laboratory scale. However, the level of maturity of this technology still remains low and does not allow its deployment on a naval platform to be considered reliably.

An aim of the invention is therefore to provide an installation adapted to treat a gaseous flow rich in hydrogen, overcoming all or part of the above drawbacks, that is to say presenting sufficient guarantees in terms of reliability, discretion, size. reduced and safety.

To this end, the subject of the invention is an installation adapted to treat a gas flow to be treated comprising at least 75% hydrogen by volume, the installation comprising a plurality of successive stages adapted to burn hydrogen from the flow gas to be treated, each of the stages comprising:

- a source of a gaseous oxidant flow comprising at least 21% oxygen by volume,

- a catalytic burner adapted to admit an inlet flow comprising hydrogen, to admit the oxidizer flow, and to produce a smoke flow, and

- an exchanger for cooling the flue gas flow by heat exchange with a refrigerant fluid and obtaining an outlet flow,

the inlet flow of a first stage of said plurality comprising the gas flow to be treated, the inlet flow of each of the other stages of said plurality respectively comprising the outlet flow of a previous stage of said plurality,

the installation being configured so that, in the stages of said plurality except the last stage, the catalytic burner burns only a fraction of the hydrogen present in the inlet flow, the outlet flow still comprising hydrogen,

the installation being further adapted to produce at least one flow of water from the outlet flow of at least one of the stages of said plurality.

According to particular embodiments, the installation comprises one or more of the following characteristics, taken in isolation or in all technically possible combinations:

- said plurality of floors consists of two or three floors;

- the installation comprises a regulation system configured to regulate, in each of the stages of said plurality, a flow rate of the oxidizer flow so that a temperature of the smoke flow is lower than a maximum temperature of between 800°C and 900°C;

- the regulation system is further configured to regulate, in each of the stages of said plurality, a flow rate of the refrigerant fluid so that a temperature of the outlet flow is greater than a minimum temperature of between 100°C and 150°C °C;

- the regulation system is further configured to regulate, in the last stage of said plurality, a flow rate of the oxidizer flow so that the smoke flow of the last stage of said plurality comprises less than 1.0% of hydrogen by volume;

- the installation further comprises: a source of a gas flow comprising at least 98% nitrogen by volume, the catalytic burner of the first stage of said plurality being adapted to admit the gas flow to dilute the smoke flow of said catalytic burner; and a separator adapted to admit the output flow of the last stage of said plurality, and to produce the water flow and a gas flow comprising at least 90% nitrogen by volume, the catalytic burner of the first stage of said plurality being adapted to admit said gas flow;

- the refrigerant fluid includes sea water or fresh water; And

- the installation comprises a pipe system adapted to admit the refrigerant fluid and pass the refrigerant fluid successively through the exchanger of each of the stages of said plurality in an inverse succession relative to a succession defined by the smoke flows.

The invention also relates to a naval platform, in particular an underwater vehicle, comprising at least one installation as described above.

The invention also relates to a process for treating a gas flow to be treated comprising at least 75% hydrogen by volume, the process using an installation and comprising the following steps:

- hydrogen combustion of the gas flow to be treated in the stages of said plurality,

- in each of the stages of said plurality, except the last stage of said plurality, admission of the inlet flow and the oxidizer flow into the catalytic burner and production of the smoke flow, the catalytic burner burning only a fraction of the hydrogen present in the input stream, the output stream still comprising hydrogen,

- in the last stage of said plurality, admission of the inlet flow and the oxidizer flow into the catalytic burner and production of the smoke flow,

- in each of the stages of said plurality, cooling of the flue gas flow in the exchanger by heat exchange with the refrigerant fluid and obtaining the outlet flow,

- production of the water flow from the outlet flow of at least one of the stages of said plurality.

The invention will be better understood on reading the description which follows, given solely by way of example and made with reference to the appended drawings, in which:

there is a schematic view of a naval platform according to the invention,

there is a schematic view of an installation according to the invention, included in the naval platform shown on the , And

there is a schematic view of an installation according to the invention, constituting a variant of the installation shown in Figures 1 and 2.

In reference to the , we describe a naval platform 10 according to the invention.

The naval platform 10 is preferably an underwater vehicle.

Alternatively, the naval platform 10 is a surface vessel.

In use, the naval platform 10 is surrounded by sea water 12.

The naval platform 10 comprises an installation 14 according to the invention.

According to a variant not shown, the naval platform 10 comprises several installations similar to the installation 14.

The installation 14 is adapted to treat a gas flow to be treated 16, comprising at least 75% hydrogen by volume, and to produce at least one water flow 18.

In the example, the installation 14 is also adapted to admit a refrigerating fluid 20, advantageously consisting of a sample of sea water 12, and to reject an effluent 22 consisting of the refrigerating fluid 20 after its use in the 'facility.

As visible on the , the gas flow to be treated 16 comes from a source 24, for example:

- a fuel cell advantageously belonging to the propulsion system (not shown) of the naval platform 10, or

- a storage of hydrogenated fuel, advantageously intended for supplying the propulsion system, and likely to produce a release of hydrogen.

The installation 14 comprises a plurality of successive stages 26, 28, 30 adapted to burn the hydrogen from the gas flow to be treated 16. The installation 14 advantageously comprises a regulation system 32, and a source 34 of a gas flow. gas 36 comprising at least 98% nitrogen by volume. The installation 14 advantageously includes a separator 38 adapted to evacuate the water flow 18, and includes a recycling loop 40.

As a variant (not shown), the installation 14 includes for example several separators adapted to evacuate several streams of water resulting from combustion in several of the stages 26, 28, 30, or even in all the stages.

According to still other variants (not shown), the installation 14 comprises a separator adapted to evacuate a flow of water resulting from the combustion in one of the stages 26, 28 (that is to say not in the top floor 30).

The installation 14 advantageously comprises a system of pipes 41 to admit the refrigerant fluid 20 and reject the effluent 22.

As will be seen, stages 26, 28, 30 are adapted to carry out staged combustion of hydrogen, and are successive from the point of view of the fumes. Floor 26 is therefore a first floor. Floor 28 is a second floor. Floor 30 is a third and last floor in the example shown on the .

Each of the stages 26, 28, 30 comprises a source 38, 40, 42 of a gaseous oxidant flow 44, 46, 48 comprising between 21% and 100% oxygen by volume. Each of the stages 26, 28, 30 comprises a catalytic burner 50, 52, 54 adapted to admit an inlet flow 56, 58, 60 comprising hydrogen, to admit the oxidant flow 44, 46, 48, and to produce a flow of smoke 62, 64, 66. Each of the stages also includes an exchanger 68, 70, 72 to cool the flow of smoke 62, 64, 66 by heat exchange with the refrigerant fluid 20 and obtain an outlet flow 74 , 76, 78.

The inlet flow 56 of the first stage 26 is constituted in the example by the gas flow to be treated 16.

The input flows 58, 60 of the other stages 28, 30 are for example constituted respectively by the output flows 74, 76 of the previous stages 26, 28.

According to a particular embodiment, not shown, the sources 38, 40, 42 are one and the same source.

According to a particular embodiment, a refrigerant circuit can be dedicated to each stage and not common to the entire installation.

According to a particular embodiment, the refrigerant circuit can supply stage 68, then stage 70 and stage 72 in that order.

The catalytic burners 50, 52, 54 are for example made up of tubes containing supported or mass catalysts, containing elements known for their capacity to carry out the hydrogen oxidation reaction. Advantageously, these elements can be metals from the supported platinum family and rare earths.

According to a particular embodiment, the catalyst consisting of the same elements is coated directly on the channels of the exchangers 68, 70, 72. In this case, the catalytic burners 50, 52, 54 and the exchangers 68, 70, 72 respectively form a only equipment.

The installation 14 is configured so that, in all stages except the last stage 30, that is to say in stages 26 and 28, the catalytic burners 50, 52 burn only a fraction of the hydrogen present in the inlet streams 56, 58, the outlet streams 62, 64 still comprising hydrogen. In other words, the catalytic burners 50, 52, that is to say all except the last, are intended to achieve partial combustion of the hydrogen present in the inlet flows 56, 58. This is obtained by the fact that the quantity of oxygen provided by the oxidant flows 44, 46 is deliberately insufficient for all the hydrogen present in the inlet flows 56, 58 to be burned.

In the example, the catalytic burner 50 of the first stage 26 is further adapted to admit the gas flow 36 rich in nitrogen to dilute the smoke flow 62, and/or a gas flow 57 coming from the separator 38.

Advantageously, in the catalytic burner 54 of the last stage 30, the combustion of the hydrogen present in the inlet flow 60 is complete, the quantity of oxygen present in the oxidant flow 48 being sufficient for this, and advantageously just sufficient for that. In other words, oxygen is found for example in the stoichiometric proportion in the oxidizer flow 48.

The regulation system 32 is advantageously configured to regulate, in each of the stages 26, 28, 30, the flow rate of the oxidant flow 44, 46, 48 so that the temperature of the smoke flow 62, 64, 66 is lower at a maximum temperature between 800°C and 900°C.

Preferably, the installation 14 is configured so that, in each stage, the oxidant is completely consumed.

The regulation system 32 is further advantageously configured to regulate, in each of the stages 26, 28, 30, the flow rate of the refrigerant fluid 20 so that the temperature of the outlet flow 74, 76, 78 is greater than a temperature minimum between 100°C and 150°C.

The regulation system 32 is for example also configured to regulate, in the last stage, that is to say the stage 30, the flow rate of the oxidant flow 48 so that the smoke flow 66 comprises less than 1.0% hydrogen by volume, and advantageously less than 0.1% hydrogen by volume, and even more advantageously less than 1 ppm hydrogen by volume.

The separator 38 is adapted to admit the outlet flow 78 of the last stage 30 and to produce the water flow 18 and a gas flow 80 comprising at least 90% nitrogen by volume. The separator 38 is for example of the float trap type.

Alternatively, the separator 38 is for example a separator tank equipped with level measurements controlling purge valves.

Advantageously, the gas flow 80 comprises at least 99% nitrogen and water by volume, the combustion carried out in the catalytic burner 54 being complete or almost complete.

The recycling loop 40 comprises for example a recirculator 82 adapted to recirculate the gas flow 80, and a heater 84, advantageously electric for heating the gas flow 80 and preheating the installation 14 during the start-up phase.

The gas flow 80 is for example admitted into the catalytic burner 50 via the recycling loop 40 in the form of the gas flow 57, with or without the addition of the gas flow 36.

Advantageously, the installation 14 comprises a purge system (not shown), for example located on the gas flow 80, and adapted to carry out a purge in the edge, particularly in the event of overpressure. This purge system is for example controlled by the regulation system 32 and a pressure measurement in the installation 14.

The pipe system 41 is for example adapted to admit the refrigerant fluid 20 and pass it successively through the exchangers 72, 70, 68 of the stages 30, 28, 26 in an inverse succession with respect to the succession defined by the smoke flows 62, 64, 66.

The operation of the installation 14 will now be described, which also illustrates a method according to the invention.

The hydrogen contained in the gas flow to be treated 16 is burned progressively in stages 26, 28, 30.

In each of the stages, except the last stage 30, that is to say in each of the stages 26, 28, the inlet flow 56, 58 and the oxidant flow 44, 46 are admitted into the catalytic burners 50, 52 which produce the smoke flows 62, 64. The catalytic burners 50, 52 burn only a fraction of the hydrogen present in the inlet flows 56,58, so that the outlet flows 74, 76 still include some 'hydrogen.

In the last stage 30, the inlet flow 60 and the oxidant flow 48 are admitted into the catalytic burner 50 which produces the smoke flow 66 advantageously devoid of hydrogen.

In each of the stages 26, 28, 30, the smoke flow 62, 64, 66 is cooled in the exchanger 68, 70, 72 by heat exchange with the refrigerant fluid 20 to obtain the outlet flows 74, 76, 78 .

In the example, the inlet flow 56 of the first stage 26 is the gas flow to be treated 16. The outlet flow 74 of the first stage 26 becomes the inlet flow 58 of the second stage 28. The outlet flow 76 of the second stage 28 becomes the input flow 60 of the third and last stage 30.

The water flow 18 is produced from the outlet flow 78 of the last stage 30, in the example by the separator 38.

Advantageously, the regulation system 32 regulates the installation 14 so that the temperature of the smoke flows 62, 64, 66 does not exceed the maximum temperature between 800°C and 900°C, and advantageously so that the oxygen content at any point in the loop complies with the values ensuring the safety of the installation. To do this, the regulation system 32 adjusts the flow rate of the oxidant flows 44, 46, 48, and the flow rate of the gas flow 80.

For each of the catalytic burners 50, 52, 54, the temperature of the fumes and/or the oxygen content downstream thereof can be lowered by reducing the flow rate of the oxidant flow 44, 46, 48, respectively, or by increasing the flow rate of the gas flow 80, that is to say by increasing the dilution of the smoke flows 62, 64, 66.

The regulation system 32 advantageously regulates the temperature of the outlet streams 74, 76, 78 at temperatures higher than the minimum temperature between 100°C and 150°C. To increase this temperature, the regulation system 32 reduces the flow of the refrigerant fluid 20 in the pipes. Conversely, to reduce this temperature, the regulation system 32 increases the flow of refrigerant fluid 20 in the pipes.

Optionally, according to a variant not shown, an additional exchanger is inserted between the exchanger 72 and the separator 38 to cool the outlet flow 78.

According to yet another variant, not only the refrigerant fluid 20 is passed through the exchanger 72, but another refrigerant fluid (not shown), so as to increase the refrigeration capacity in the last stage 30.

According to yet another variant, already described above, the exchangers 68, 70, 72 are made independent of each other, so as to be able to admit different refrigerant flows in each of these exchangers, and to adjust the refrigeration capacity of each of the stages, in particular by adapting the flow of refrigerant passing through each of the exchangers.

The compressor 82 circulates the gas flow 80 in the recycling loop 40. The source 34 makes it possible to make a supplement of inert gas via the gas flow 36 admitted into the catalytic burner 50.

Advantageously, when the installation 14 is started, it is placed under non-pressurized nitrogen thanks to the gas flow 36 and the recirculation loop 40. The heater 84 heats the gas flow 80 in order to bring the catalytic burners 50, 52, 54 at a starting temperature of the catalytic combustion of hydrogen.

In normal operation, oxygen is introduced sub-stoichiometrically into all stages except the last stage 30. In these stages, the oxidation reaction occurs, leading to the transformation of part of the hydrogen present in the input flow 56, 58 in water vapor and leads to a release of heat. The oxygen is advantageously completely consumed by these reactions. The flow of oxygen supplied via the oxidant flows 44, 46 is for example controlled from the temperature of the smoke flows 62, 64 or by the flow of hydrogen at the inlet of each of the stages, calculated from the measurements of the flow rates of the gas flow 36 and the gas flow 80 and the hydrogen content at the inlet of each of the stages. At the outlet of each of the stages, the oxygen content is preferably measured and this measurement is used by the regulation system 32 to adjust the quantity of oxidizer sent to each of the stages.

The temperature of the smoke streams 62, 64, 66 being kept lower than the maximum temperature, this avoids degradation of the catalysts present in the catalytic burners 50, 52, 54.

At the outlet of each of the stages 26, 28, 30, the exchangers 68, 70, 72 supplied by the refrigerant fluid 20 make it possible to lower the temperature of the outlet flows 74, 76, 78 to a temperature higher than the minimum temperature, this which prevents water condensation in these flows.

Alternatively, at the outlet of the exchanger 72, an additional exchanger (not shown) makes it possible to further cool the flow 78. The regulation system 32 adjusts the refrigerant flow rate of this additional exchanger in order to allow the separator 38 to produce the flow of water 18.

In the example, the catalytic combustion and cooling operations are repeated three times. At the exit of the last stage, that is to say stage 30 in the example, there is advantageously no more hydrogen nor oxygen in the smoke flow 66. The water produced by the successive combustions is completely or partially separated from the gases in the separator 38. The gas flow 80 is advantageously made up of nitrogen and water, and circulates via the recirculation loop 40 in order to dilute the reagents in each of the catalytic burners 50, 52, 54.

Advantageously, the installation 14, apart from the compressor 82 and the heater 84, can be manufactured in a single part by additive manufacturing.

Thanks to the characteristics described above, the installation 14 makes it possible to eliminate hydrogen from the gas flow to be treated 16 in a reliable, discreet and safe manner, with a reduced footprint. The lack of oxygen, particularly in stages 26 and 28, makes it possible to avoid the explosion of the mixture by ensuring a hydrogen content higher than the upper explosive limit.

The reaction temperature of the gases, that is to say in particular the temperature of the smoke flows 62, 64, 66, is limited by staging the reaction in order to minimize the quantity of energy released in each of the stages. This staging is carried out by introducing the oxidizer as a limiting reagent at each stage.

Advantageously, the reactive mixture seen by the catalytic burners 50, 52, 54 is diluted using the recirculation loop 40.

The reaction temperature is also limited by the refrigeration carried out at the outlet of the catalytic burners 50, 52, 54.

After the last stage 30, the hydrogen and oxygen possibly recirculating in the recirculation loop 40 and are only present in trace form, in quantities less than 1 ppm by volume respectively. A system for measuring these constituents in the recirculation loop advantageously makes it possible to control their contents to ensure the safety of the installation.

In reference to the , we describe an installation 114 constituting a variant of the installation 14 shown in Figures 1 and 2. The installation 114 is similar to the installation 14. Similar elements bear the same numerical references and will not be described again. Only the differences will be described in detail below.

Facility 114 does not include floor 30 of Facility 14, but only floors 26 and 28.

Stage 28 is therefore the last stage of installation 114. The outlet flow 76 is admitted into the separator 38.

Stage 28 of installation 114 has all the properties of stage 30 of installation 14. In particular, the catalytic burner 52 achieves advantageously complete combustion of the hydrogen still present in the inlet flow 58.

The exchangers 68, 70 are independent of each other. The exchanger 68 receives a refrigerant fluid 22A, for example seawater, and rejects an effluent 22. The exchanger 70 receives the refrigerant fluid 20, for example seawater, and rejects an effluent 22A.

The exchangers 68, 70 can therefore be adjusted independently of each other so as to adapt the refrigeration capacity of each of the stages, which are not linked by the same refrigerant flow rate.

Installation 114 operates in a similar manner to installation 14 and has substantially the same advantages.

Example :

The following example concerns the variant described above, with two stages 26, 28. The gas flow to be treated 16 is pure hydrogen and has a flow rate of 0.6470 kg/h.

The oxidant flows 46, 48 consist of pure oxygen and have a flow rate of 2.600 kg/h and 2.535 kg/h respectively.

Upstream of the catalytic burner 50 of the first stage 26, the mixture of the gas flow to be treated 16, the oxidant flow 44 and the recirculated gas flow 80 is at a pressure of 1,400 bar and a temperature of 43.4°C. Its flow rate is 93.21 kg/h. In this mixture, the volume fraction of hydrogen is 0.08, that of oxygen 0.02, that of nitrogen 0.88, and that of water 0.03.

The smoke flow 62 has a temperature of 402.3°C. Its mole fraction of hydrogen is 0.04 and that of oxygen is 0.0000.

The smoke flow 64 has a temperature of 537.5°C.
Its mole fraction of nitrogen is 0.86 and its mole fraction of water is 0.14. In this flow, the mole fraction of hydrogen and oxygen is 0.0000.

Water flow 18 has a temperature of 40.0°C and a flow rate of 5.782 kg/h. Its mole fraction in water is 1.0000.

The gas flow 80, or recycled gas 57, is at a pressure of 1.4 bar, a temperature of 40.0°C and its flow rate is 89.96 kg/h. Its mole fraction of nitrogen is 0.95 and its mole fraction of water is 0.05. Its mole fraction of hydrogen and oxygen is 0.00.

The total oxygen consumption is 5.14 kg/h.

Claims (10)

Installation (14; 114) adapted to treat a gas flow to be treated (16) comprising at least 75% hydrogen by volume, the installation (14; 114) comprising a plurality of stages (26, 28, 30; 26 , 28) successive adapted to burn hydrogen from the gas flow to be treated (16), each of the stages (26, 28, 30; 26, 28) comprising:
- a source (38, 40, 42; 38, 40) of a gaseous oxidant flow (44, 46, 48; 44, 46) comprising at least 21% oxygen by volume,
- a catalytic burner (50, 52, 54; 50, 52) adapted to admit an inlet flow (56, 58, 60; 56, 58) comprising hydrogen, to admit the oxidant flow (44, 46 , 48; 44, 46), and to produce a flow of smoke (62, 64, 66; 62, 64), and
- an exchanger (68, 70, 72; 68, 70) for cooling the flue gas flow (62, 64, 66; 62, 64) by heat exchange with a refrigerant fluid (20) and obtaining an outlet flow (74 , 76, 78; 74, 76),
the inlet flow (56) of a first stage (26) of said plurality comprising the gas flow to be treated (16), the inlet flow (58, 60; 58) of each of the other stages (28, 30 ; 28) of said plurality respectively comprising the output stream (74, 76; 74) of a previous stage of said plurality,
the installation (14; 114) being configured so that, in the stages (26, 28, 30; 26, 28) of said plurality except the last stage (30), the catalytic burner (56, 58; 56) burns only a fraction of the hydrogen present in the inlet flow (56, 58, 60; 56, 58), the outlet flow (74, 76; 74) still comprising hydrogen,
the installation (14; 114) being further adapted to produce at least one flow of water (18) from the outlet flow (74, 76, 78; 74, 76) of at least one of the stages (26, 28, 30; 26, 28) of said plurality. Installation (14; 114) according to claim 1, in which said plurality of stages (26, 28, 30; 26, 28) consists of two or three stages. Installation (14; 114) according to claim 1 or 2, comprising a regulation system (32) configured to regulate, in each of the stages (26, 28, 30; 26, 28) of said plurality, a flow rate of the oxidant flow (44, 46, 48; 44, 46) so that a temperature of the smoke flow (62, 64, 66; 62, 64) is lower than a maximum temperature of between 800°C and 900°C. Installation (14; 114) according to claim 3, in which the regulation system (32) is further configured to regulate, in each of the stages (26, 28, 30; 26, 28) of said plurality, a flow rate of the fluid refrigerant (20) so that a temperature of the outlet flow (74, 76, 78; 74, 76) is greater than a minimum temperature of between 100°C and 150°C. Installation (14; 114) according to claim 3 or 4, in which the regulation system (32) is further configured to regulate, in the last stage (30; 28) of said plurality, a flow rate of the oxidant flow (48 ; 46) so that the flow of fumes (66; 64) from the last stage (30; 28) of said plurality includes less than 1.0% hydrogen by volume. Installation (14; 114) according to any one of claims 1 to 5, further comprising:
- a source (34) of a gas flow (36) comprising at least 98% nitrogen by volume, the catalytic burner (50) of the first stage (26) of said plurality being adapted to admit the gas flow (36 ) to dilute the flow of smoke (62) from said catalytic burner (50), and
- a separator (38) adapted to admit the outlet flow (78; 76) of the last stage (30; 28) of said plurality, and to produce the water flow (18) and a gas flow (80) comprising at less 90% nitrogen by volume, the catalytic burner (50) of the first stage (26) of said plurality being adapted to admit said gas flow (57). Installation (14; 114) according to any one of claims 1 to 6, in which the refrigerant fluid (20) comprises sea water (12) or fresh water. Installation (14; 114) according to any one of claims 1 to 7, comprising a system of pipes (41) adapted to admit the refrigerant fluid (20) and pass the refrigerant fluid (20) successively into the exchanger (68). , 70, 72; 68, 70) of each of the stages (26, 28, 30; 26, 28) of said plurality in an inverse succession with respect to a succession defined by the smoke flows (62, 64, 66; 62 , 64). Naval platform (10), in particular underwater vehicle, comprising at least one installation (14; 114) according to any one of claims 1 to 8. Method for treating a gas flow to be treated (16) comprising at least 75% hydrogen by volume, the method implementing an installation (14; 114) according to any one of claims 1 to 8 and comprising the steps following:
- hydrogen combustion of the gas flow to be treated (16) in the stages (26, 28, 30; 26, 28) of said plurality,
- in each of the stages (26, 28, 30; 26, 28) of said plurality, except the last stage (30; 28) of said plurality, admission of the input flow (56, 58, 60; 56, 58) and the oxidant flow (44, 46, 48; 44, 46) in the catalytic burner (50, 52, 54; 50, 52) and production of the smoke flow (62, 64, 66; 62, 64), the catalytic burner (50, 52, 54; 50, 52) burning only a fraction of the hydrogen present in the inlet flow (56, 58, 60; 56, 58), the outlet flow (74, 76, 78 ; 74, 76) still comprising hydrogen,
- in the last stage (30; 28) of said plurality, admission of the inlet flow (60; 58) and the oxidant flow (48; 46) into the catalytic burner (54; 52) and production of the smoke flow (62; 64),
- in each of the stages (26, 28, 30; 26, 28) of said plurality, cooling of the smoke flow (62, 64, 66; 62, 64) in the exchanger (68, 70, 72; 68, 70 ) by heat exchange with the refrigerant fluid (20) and obtaining the outlet flow (74, 76, 78; 74, 76),
- production of the water flow (18) from the outlet flow (74, 76, 78; 74, 76) of at least one of the stages of said plurality.