Hydrogen internal combustion engine installation

Abstract

The invention relates to an internal combustion engine installation using partially or totally hydrogen as fuel, said installation comprising an internal combustion engine, said engine being - in fluid connection, upstream, with an intake line (4) supplied with fuel including hydrogen coming from a liquid hydrogen tank (2), - in fluid connection, downstream, with an exhaust line (1) comprising a hydrogen-sensitive selective NOx reduction catalysis device (SCR-1), said installation also comprising a degassing hydrogen capture line (3) for capturing degassing hydrogen from the liquid hydrogen tank, said hydrogen capture line being in fluid connection - with the exhaust line (1) upstream of the hydrogen-sensitive selective NOx reduction catalysis device (SCR-1) - and / or with the intake line (4). Figure 1 to be published

Description

Title of the invention: Hydrogen internal combustion engine installation Technical field

[0001] The present invention relates to the field of pollution control and safety of hydrogen internal combustion engines.

[0002] The transport sector, and in particular land transport, is forced, like other sectors, to reduce its CO2 emissions in order to limit global warming to 2°C by the end of the century. In order to meet this societal challenge, mobility technologies must evolve to aim for CO2 emissions close to zero. Thus, three main families of technologies are envisaged to achieve this objective, each of which can be more or less adapted to a specific application: - The all-electric solution: which combines a traction battery and an electric powertrain. The latter can use one or more electric machines depending on the power required by the application in question. This solution has two major drawbacks: the volume and mass of the batteries are significant, limiting their use to vehicles that do not require high energy requirements; in addition, their recharge time is significant, thus penalizing service continuity. - The fuel cell system, which is a chemical converter that creates electricity from a reaction between hydrogen and air. The electricity thus produced is used by an electric powertrain similar to that of the all-electric vehicle. The advantages of the fuel cell compared to the battery are in the energy storage density, higher with hydrogen, and the speed of filling the hydrogen storage tank. On the other hand, the fuel cell is an expensive solution due to the use of precious metals. The latter also presents increased complexity in transient management.

[0003] To overcome the various drawbacks listed above, a third solution is to use hydrogen as fuel in an internal combustion engine. This approach brings several advantages: - From a user point of view, this approach allows for certain specific applications such as heavy goods vehicles, construction machinery, maritime or river boats to offer interesting characteristics in terms of autonomy, and especially recharge time, which battery systems cannot offer. Only the fuel cell would be able to ensure an identical level of performance, but with a much higher cost. - The hydrogen internal combustion engine is based on mature, reliable and cost-optimized technology, allowing the use of existing industrial tools without major modifications, unlike alternative electric solutions which require disruptive production methods. - The hydrogen internal combustion engine is virtually insensitive to external conditions, such as extreme cold and hot temperatures, altitude, and the presence of dust in the air. It is also insensitive to vibrations. These advantages make it particularly relevant for applications such as construction or mining machinery. - The hydrogen internal combustion engine is much less sensitive than the fuel cell to the quality of the hydrogen used. By quality, we mean the degree of purity of the hydrogen, as well as the low presence of contaminants in it, the possible contaminants being listed in the ISO 14687-2 standard. Examples include argon, CO2 and sulfur compounds. It is therefore possible to use lower quality hydrogen in the hydrogen internal combustion engine, with an advantage in terms of its cost.

[0004] Thus, the hydrogen internal combustion engine makes it possible to respond in the short term to the need to reduce CO2 emissions for different applications. This hydrogen engine can either be designed and manufactured directly from a blank sheet, or by converting gasoline, diesel or gas engines currently in use in order to accelerate the ecological transition with an immediately ready solution. It is to be equipped with one or more cryogenic hydrogen tanks, in order to be able to store a larger quantity of hydrogen in liquefied form in the vehicle.

[0005] It can be used on any means of transport, whether land (light vehicles, utility vehicles, heavy goods vehicles, coaches, buses, so-called “off-road” vehicles such as agricultural and construction machinery, etc.), sea or air. Prior art

[0006] Thermal engines powered by hydrogen via cryogenic tanks have many advantages, the main one being extended autonomy. However, the problem of storing hydrogen in liquid form is based on the need to maintain it at cryogenic temperatures, at very low temperatures (-253°C). However, at constant pressure, when the hydrogen heats up, it gasifies, the liquid transforms into gas and causes a rise in pressure inside the tank. This gas is generated mainly when filling the tank, during long storage periods, but also during engine operation, creating an increase formation of the gaseous atmosphere in the tank, and this is even more so when the outside temperature is high.

[0007] And when the critical capacity of the tank to withstand the increase in pressure is reached, it is then necessary to degas this hydrogen. This degassing phenomenon is called "boil-off" in English.

[0008] However, degassing hydrogen near the tanks has at least two disadvantages: on the one hand, it reduces the autonomy of the vehicles, since it is a dry loss of hydrogen, on the other hand the hydrogen thus released, even if it is not directly a greenhouse gas, is considered an indirect climatic gas, by inducing disturbances on the methane, ozone and water vapor contained in the atmosphere.

[0009] It is already known, in particular from patent application US 2022 / 0397240, a cryogenic tank containing liquefied hydrogen, which is provided with degassing means comprising a degassing valve, these degassing means also comprising a mixing chamber where the hydrogen is mixed with air, then a catalytic device to promote the reaction of the hydrogen with the oxygen in the air and produce water vapor from the hydrogen / air mixture. This is an interesting solution for not releasing, or for releasing less degassed hydrogen into the atmosphere, but it is cumbersome to implement, and it does not resolve the issue of loss of autonomy due to this controlled hydrogen leak that is degassing.

[0010] The invention then aims to remedy these drawbacks. It aims to improve the operation of equipment comprising thermal engines supplied with hydrogen via cryogenic tanks. Summary of the invention

[0011] The invention then firstly relates to an internal combustion engine installation using partially or totally hydrogen as fuel, said installation comprising an internal combustion engine, said engine being - in fluid connection, upstream, with an intake line supplied with fuel including hydrogen coming from at least one liquid hydrogen tank, - in fluid connection, downstream, with an exhaust line comprising at least one hydrogen-sensitive selective NOx reduction catalysis device, Said installation also comprises a degassing hydrogen capture line for capturing the degassing hydrogen from the or at least one of the liquid hydrogen tanks, said hydrogen capture line being in fluid connection with the exhaust line upstream of the hydrogen-sensitive selective NOx reduction catalysis device and / or with the intake line.

[0012] In this text, the term "degassing hydrogen" means hydrogen resulting from the degassing of liquefied hydrogen stored in one or more tanks; it is therefore essentially in gaseous form.

[0013] In this text, the term "liquid hydrogen tank" means a tank capable of storing hydrogen in liquefied form, at a very low temperature therefore, which is why it can also be referred to indifferently as a cryogenic tank.

[0014] In the present text, the terms “upstream” and “downstream” are understood to refer to the general direction of circulation of the gases / fluids concerned, for example hydrogen, intake gases, or exhaust gases.

[0015] The invention therefore sought not to treat the degassing hydrogen from the liquefied hydrogen tank, but to exploit it to the advantage of the overall operation of the engine: this degassing hydrogen is here recovered - either to be returned to the engine intake, which makes it possible not to / to reduce the autonomy of the tank less: the quantity of this degassing hydrogen, as mentioned previously, being variable and depending in particular on the outside temperature, it is very advantageous to recover this degassing hydrogen which can correspond to significant quantities, as fuel for the engine, - either to be returned to the exhaust, in the area where it is useful for a pollution control device, in particular for selective reduction of NOx operating with hydrogen: it thus makes it possible to replace, at least partially, as required, an external supply of hydrogen, - either to be partly returned to the intake and partly to the exhaust, depending on the needs for catalytic reduction of NOx, in particular: depending on the NOx content to be treated in the exhaust gases, the process makes it possible to choose the most optimal distribution, which can go from 100% to the exhaust to 100% to the intake.

[0016] It should be noted that, within the framework of the invention, it may be preferable to choose to send all of the hydrogen to the intake (in particular if the exhaust line is equipped with pollution control means, in particular for treating NOx, operating with elements / components other than hydrogen) or all of the degassing hydrogen to the exhaust, which then simplifies the degassing hydrogen circulation circuit.

[0017] It should also be noted that in the remainder of this text, we speak of a cryogenic tank to equip the installation, for the sake of brevity, but the installation may comprise several tanks, all of which preferably use the improved degassing system according to the invention.

[0018] A preferred example of a NOx catalytic reduction system with this type of device operating with hydrogen, entirely applicable in the context of The present invention is thus described in patent FR 3013381 (corresponding to application US 2016 / 0298514): it describes a technology which uses two catalysts for selective catalytic reduction of NOx: a catalyst sensitive to ammonia and a catalyst sensitive to hydrogen.

[0019] Advantageously according to the invention, the or at least one of the liquid hydrogen tanks can be equipped with a degassing device, comprising in particular at least one degassing valve, said degassing device being in fluid connection with the degassing hydrogen capture line.

[0020] This line is preferably a line dedicated to degassing, and therefore separate from the (main) hydrogen supply line from the tank to the engine intake line.

[0021] Advantageously according to the invention, the installation may comprise at least one device for controlling the distribution of the portion of the hydrogen captured from the capture line which is injected into the exhaust line and of the portion of the hydrogen captured from the capture line which is injected into the intake line, in particular as a function of the hydrogen requirements of the hydrogen-sensitive selective NOx reduction catalysis device.

[0022] This control device may comprise at least one valve on the degassing hydrogen capture line which is controlled by computer / electronic means of the computer or calculator type: by this or these valves, the flow rate of degassing hydrogen which is sent to the intake and / or which is sent to the exhaust will be managed / controlled. In the embodiment where degassing hydrogen is sent only to the intake, or only to the exhaust, this control device makes it possible to control the flow rate of degassing hydrogen supplied respectively to the intake or to the exhaust.

[0023] Preferably, the exhaust line comprises at least one NOx probe, preferably a first NOx probe upstream of said hydrogen-sensitive selective NOx reduction catalysis device and a second NOx probe downstream of said hydrogen-sensitive selective NOx reduction catalysis device.

[0024] With this or these probes, we will be able to determine the quantity of hydrogen necessary for the treatment of NOx, and thus control the flow of degassing hydrogen necessary to send to the exhaust.

[0025] However, it may be that the quantity (flow rate) of available degassing hydrogen is insufficient. In this case, in particular, it may be provided that the exhaust line further comprises at least one hydrogen injector upstream of the hydrogen-sensitive selective NOx reduction catalysis device: the necessary hydrogen content can then be supplemented with an additional supply of hydrogen via this or these injectors.

[0026] As described in the aforementioned patent, the exhaust line according to the invention may also comprise at least one catalysis device for selective reduction of NOx sensitive to ammonia.

[0027] In this configuration, the ammonia-sensitive selective NOx reduction catalysis device may be arranged in the exhaust line upstream or downstream of the hydrogen-sensitive selective NOx reduction catalysis device.

[0028] In the event that it proves necessary, when it is planned to send at least part of the degassing hydrogen to the exhaust, it may be provided that the exhaust line comprises at least one pressure reducing member, to locally reduce the pressure within the exhaust line. (The pressure reducing member is to be understood as a member capable of generating a local pressure reduction), this in order to guarantee a sufficient flow rate of the degassing hydrogen to the exhaust line: it may in fact be useful to create a localized depression at the junction between the exhaust line and the degassing hydrogen collection line. The pressure reducing member may in particular take the form of an orifice plate, a diaphragm plate, a nozzle or a Venturi tube.

[0029] According to a variant of the invention, the installation according to the invention may also comprise a line for capturing the hydrogen present within a casing of said internal combustion engine with a de-oiling system, said line for capturing the hydrogen present within said casing being in fluid connection with the exhaust line upstream of the hydrogen-sensitive selective NOx reduction catalysis device and / or with the intake line. A pressure-reducing member may be provided in the exhaust line, such as one of those mentioned above.

[0030] Thus, by also recovering this residual hydrogen called "blow-by" from the engine casing, a second additional source of hydrogen is obtained, which can, like the degassing hydrogen from the cryogenic tank, be used either to supply the exhaust to a pollution control device such as an RCS which requires a reducing agent in the form of hydrogen, or to supply the engine as fuel to the intake. The autonomy of the installation is further improved, while further reducing the hydrogen content likely to be released into the atmosphere, and, above all, while ensuring the safety of the installation.

[0031] It should be remembered that the so-called SCR (Selective Catalytic Reduction) devices use a technique that has been widely used on diesel vehicles over the last fifteen years. This SCR catalytic device makes it possible to selectively reduce NOx to nitrogen through the action of a reducing agent.

[0032] The invention also relates to a method for controlling a hydrogen internal combustion engine installation as described above, the method implementing the following steps: - hydrogen is captured during degassing of the liquid hydrogen tank(s) in the degassing hydrogen capture line - at least a portion of the degassing hydrogen captured from the capture line is injected into the exhaust line to treat the NOx in association with the hydrogen-sensitive selective NOx reduction catalysis device, and / or - at least a portion of the hydrogen captured from the capture line is injected into the intake line.

[0033] Preferably, the control method according to the invention can also comprise the following steps: - residual hydrogen present in the engine crankcase is also captured in a hydrogen capture line from said crankcase, - at least a portion of the hydrogen captured from the residual hydrogen capture line from the crankcase is injected into the exhaust line to treat the NOx in association with the hydrogen-sensitive selective NOx reduction catalysis device, and / or - at least a portion of the hydrogen captured from the crankcase hydrogen capture line is injected into the intake line.

[0034] The control method thus uses in a similar manner the hydrogen coming from the degassing of the cryogenic tank and the residual hydrogen from the engine crankcase, if the latter is also recovered via a residual hydrogen capture line.

[0035] The control method according to the invention may provide for controlling the distribution of the portion of the hydrogen captured from the degassing hydrogen capture line which is injected into the exhaust line and of the portion of the hydrogen captured from the capture line(s) which is injected into the intake line as a function of the hydrogen requirements of the hydrogen-sensitive selective NOx reduction catalysis device.

[0036] It can also provide differentiated control depending on the moment in the operating cycle of the installation, for example with a return entirely to the intake at the start of the cycle then entirely to the exhaust, for example as soon as the temperature of the exhaust gases has reached a certain threshold.

[0037] The control method according to the invention can be part of the control method of the overall installation, with as input data the necessary quantity of hydrogen to treat the NOx in the catalytic device at the exhaust (via NOx measuring probes for example, one or more temperature sensors or by estimations ...), the available quantity (the flow rate) of degassing hydrogen, and possibly actually the available quantity of residual hydrogen coming from the crankcase if it is also recovered, the quantity of fuel necessary to provide the power required by the engine, and at the output the proportion of recovered hydrogen (from degassing, plus possibly that coming from the engine crankcase) which will supply the intake and / or the exhaust, using an on-board computer, and this from the start of the engine throughout its operating cycle.

[0038] The invention also relates to any land, sea or air vehicle which includes the installation described above.

[0039] The invention also relates to the installation previously described, but which is equipped with one or more exhaust gas depollution devices, of the NOx treatment type or others, none of which require hydrogen to be operational. In this case, it provides that all the recovered hydrogen (from degassing, and from the engine crankcase if it is also intended to be recovered) can be returned to the intake only.

[0040] Other characteristics and advantages of the installation and the method according to the invention will appear on reading the following description of non-limiting examples of embodiments, with reference to the appended figure described below. List of figures

[0041] [Fig.l] [Fig.l] illustrates in an extremely schematic manner a portion of the hydrogen internal combustion engine installation according to a first embodiment of the invention.

[0042] [Fig.2] [Fig.2] illustrates in an extremely schematic manner a portion of the hydrogen internal combustion engine installation according to a second embodiment of the invention.

[0043] The figures do not respect the scale between the different components represented. The same references from one figure to another represent the same components / fluids. Description of the embodiments

[0044] The present invention relates to a hydrogen internal combustion engine installation. It may be an internal combustion engine directly designed to operate with dihydrogen (more commonly referred to as hydrogen in the remainder of this text) as fuel, or, alternatively, it may be a gasoline, diesel or gas internal combustion engine used with dihydrogen as fuel, this approach being known as "retrofitting".

[0045] By hydrogen internal combustion engine is meant a combustion engine internal combustion engine that can operate partially or totally with hydrogen as fuel. The amount of hydrogen used as fuel in this context of the invention is between 10% and 100% vol. Preferably, the internal combustion engine can operate with mainly hydrogen as fuel. Preferably, the internal combustion engine can operate solely with hydrogen as fuel (with the exception of impurities).

[0046] Conventionally, an installation of a hydrogen internal combustion engine comprises: - at least one cylinder (generally 3 or 4 cylinders) within a crankcase, in which a piston moves, the piston and the cylinder delimiting with a cylinder head a combustion chamber, - an air intake line, with a set of pipes, to supply the combustion chamber with air, - a fuel injection, direct or indirect, to supply the combustion chamber with fuel, and - an exhaust line, with a set of pipes, for the evacuation of burnt gases from the combustion chamber to the atmosphere.

[0047] According to the invention, the hydrogen internal combustion engine installation supplied by a cryogenic tank comprises an exhaust line preferably comprising a hydrogen-sensitive NOx nitrogen oxide reduction catalysis device. The exhaust line comprises a NOx SCR catalyst whose reducing agent is hydrogen, to ensure the post-treatment of the exhaust gases. The SCR post-treatment consists of reducing the nitrogen oxides NO and NO2 (commonly called NOx) on a catalytic device whose formulation generally comprises at least one noble metal impregnated on a support. The state-of-the-art supports generally used are alumina A12O3, cerium oxides CeO2, zirconia ZrO2, tungsten WO3, or titanium TiO2, used alone or in combination, zeolites (ZSM-5, beta, chabazite) and perovskite oxides.Alternatively, formulations using these same supports in combination with non-noble metals such as copper or iron, or with metallic (e.g. PtNi) or non-metallic alloys, also exhibit interesting performance in terms of activity and selectivity. This catalyst promotes the reduction of NOx to nitrogen, by reaction with the reducing agent. In addition, hydrogen is an excellent NOx reducer at temperatures of barely 100°C. For example, hydrogen SCR catalysts with a composition based on Pt / SiO2 or Pt / TiO2-ZrO2 Pd / WO3 / ZrO2 have shown good activity and selectivity from 90°C. Thus, the NOx level in the exhaust line is reduced.

[0048] In addition, the installation comprises a line for capturing the degassing hydrogen from the cryogenic tank to the atmosphere, to evacuate the degassing hydrogen from the tank without release (or minimal release) to the hydrogen atmosphere.

[0049] The degassing hydrogen capture line ("boil-off") according to the invention comprises a pipe or a set of pipes. This capture line is connected to (is in fluid connection with) the exhaust line upstream of the hydrogen-sensitive NOx reduction catalysis means, to inject into the exhaust line at least a portion of the captured degassing hydrogen. Thus, the hydrogen-sensitive RCS catalyst is supplied with reducing agent taken directly from the degassing hydrogen of the cryogenic tank: the invention makes it possible to simultaneously ensure the safety of the cryogenic tank and the depollution of the internal combustion engine. The use of this degassing hydrogen makes it possible to reduce NOx emissions without having to use: - either only hydrogen contained in the vehicle's storage tanks, which would have the effect of reducing its autonomy, - or only to an additional reducing agent, which would require the use of a dedicated tank reducing the volume available on board the vehicle. In addition, most known reducing agents, for example urea, emit CO2 emissions when they decompose in the exhaust line.

[0050] According to one embodiment of the invention, the degassing hydrogen capture line can be further connected to the intake line of the internal combustion engine. In this way, a portion of the degassing hydrogen can be recycled / used as fuel at the intake of the internal combustion engine. Thus, the efficiency of the engine can be improved.

[0051] For this embodiment, the degassing hydrogen capture line may comprise at least one controlled valve for controlling a flow of hydrogen injected into the exhaust line and / or a flow of hydrogen recycled to the intake of the internal combustion engine. For example, the capture line may comprise two controlled valves, one upstream of the connection to the exhaust line and the other upstream of the connection to the intake line. In this example, the valves may be controlled simultaneously, so that when one of them opens, the second closes. This control mode makes it possible to divert between 0 and 100% of the flow of degassing hydrogen to the exhaust line in order to use the appropriate quantity of degassing hydrogen as a reducing agent for the RCS catalysis reaction, depending on the total quantity of NOx to be treated.Alternatively, the collection line may comprise a single valve, for example a three-way valve, with one inlet and two outlets.

[0052] According to one aspect of the invention, the exhaust line may further comprise a hydrogen injector, this hydrogen injector being arranged upstream of the hydrogen-sensitive selective NOx reduction catalysis means. Thus, it is possible to increase the quantity of hydrogen in the exhaust line if the quantity coming from the degassing hydrogen capture line is insufficient for effective NOx catalysis. The hydrogen injected by this injector can come from the fuel tank.

[0053] According to one aspect of the invention, the exhaust line may comprise at least one NOx sensor. Thus, the quantity of NOx can be measured within the exhaust line. Alternatively to the NOx sensor, the quantity of NOx within the exhaust line can be estimated by logical and / or computer means (for example a computer of the internal combustion engine). This quantity of NOx can be used in particular for controlling the hydrogen internal combustion engine installation.

[0054] Where appropriate, the opening of at least one valve of the degassing hydrogen capture line may depend on the quantity of NOx to be treated in the exhaust line, or the quantity of hydrogen injected by the injector may depend on the quantity of NOx in the exhaust line and the quantity of hydrogen injected by the capture line. Indeed, the RCS catalysis can be adapted according to the quantity of NOx to be treated by adjusting the quantity of hydrogen injected into the exhaust line. If the quantity of degassing hydrogen is greater than the quantity required to carry out the NOx reduction reaction, then the corresponding excess portion of the degassing hydrogen can be recycled to the intake of the heat engine, so that the hydrogen contained therein is burned in the combustion chamber, and produces work.Conversely, if the quantity of degassing hydrogen is less than the quantity required to carry out the NOx reduction reaction, an additional supply of hydrogen can possibly be made additionally in the exhaust line, upstream of the RCS catalyst, for example by using an injector.

[0055] According to a variant of this configuration, the exhaust line may comprise a NOx probe upstream of the hydrogen-sensitive selective NOx reduction catalysis means and a NOx probe downstream of the hydrogen-sensitive selective NOX reduction catalysis means. Thus, these measurements make it possible to know the efficiency of the RCS catalyst, and to adjust the quantity of hydrogen to be injected into the exhaust line.

[0056] According to one option, the exhaust line may include a temperature sensor placed in the exhaust line, in particular at the inlet of the exhaust line to know at any time the temperature of the exhaust gases circulating in this line. Alternatively, it may be provided to use logical and / or in formats that allow the temperature of the exhaust gases circulating in the line to be estimated at any time.

[0057] According to one embodiment of the invention, the exhaust line may further comprise a selective NOx reduction catalysis means sensitive to ammonia. In other words, the exhaust line comprises a NOx SCR catalyst whose reducing agent is ammonia. In this way, the exhaust line comprises two SCR catalysts: one sensitive to hydrogen and one sensitive to ammonia. This ammonia-sensitive SCR device contains a catalyst. In state-of-the-art industrial applications, the most common SCR catalyst formulations are based on iron- or copper-exchanged zeolites, or based on vanadium oxide V2O5. To introduce gaseous ammonia into the exhaust gas treatment system, it is known to produce it directly in the pipe carrying these gases to the RCS system by vaporizing an aqueous solution of a precursor of this reducing agent such as, for example, urea.Urea, injected at an average exhaust temperature generally of 150 to 400°C, releases ammonia through successive thermolysis and hydrolysis reactions. Other ammonia precursor compounds can be used under similar conditions. An ammonia injector is usually used to introduce the aqueous urea solution into the pipe carrying the exhaust gases to the SCR catalyst, upstream of it. A mixer or blender, installed between this injector and the SCR catalyst, can be used to improve the vaporization of the aqueous urea solution spray into the exhaust gas flow. This ammonia can be injected into the exhaust line upstream of the ammonia-sensitive SCR catalyst. Ammonia can be obtained indirectly by decomposition of a precursor injected in liquid form, generally urea in aqueous solution at 32.5%m better known under the commercial name "AdBlue™" or "DEF™".

[0058] According to one embodiment, the SCR catalyst using hydrogen as a reducing agent can be mounted upstream of the SCR catalyst using ammonia as a reducing agent. This architecture makes it possible to optimize NOx depollution for low exhaust temperatures, typically below 150°C, thanks to the hydrogen-sensitive SCR catalyst mounted in a position close to the outlet of the combustion chamber. Indeed, this type of SCR catalyst is particularly suitable for temperatures between 80 and 150°C.

[0059] When the operating conditions of the heat engine evolve towards higher temperature levels, the hydrogen-sensitive RCS catalyst will gradually become less effective, unlike the ammonia-sensitive RCS catalyst which will become increasingly effective. This exhaust line architecture therefore presents an obvious advantage, by making it possible to aim for pollution control NOx over a wider exhaust temperature range compared to using a single SCR catalyst formulation.

[0060] Alternatively, the SCR catalyst using ammonia as a reducing agent can be mounted upstream of the SCR catalyst using hydrogen as a reducing agent. This architecture is particularly advantageous for treating nitrogen oxides when the exhaust gas temperature is high, typically above 150°C. Since the SCR catalyst using hydrogen as a reducing agent is more suitable for low exhaust temperatures, it is positioned in a position remote from the combustion chamber, downstream of the SCR catalyst using ammonia as a reducing agent. Thus, the thermal losses experienced by the SCR catalyst using ammonia as a reducing agent and by the intermediate exhaust line between the two SCR catalysts lead to a reduced exhaust gas temperature at the inlet of the hydrogen-sensitive SCR catalyst, the level of which will depend on the intensity of these thermal losses.For example, a very distant position of the hydrogen-sensitive SCR catalyst from the ammonia-sensitive SCR catalyst will result in significant heat losses, and therefore reduce the exhaust gas temperature at the hydrogen-sensitive SCR catalyst.

[0061] According to one embodiment option, the exhaust line may comprise other post-treatment devices, such as a particulate filter. Thus, the pollutant emissions from the hydrogen internal combustion engine installation are reduced. Such a particulate filter generally takes the form of a filter with porous walls responsible for continuously filtering particles, including the finest, typically less than 50 nm. This particulate filter may be positioned either upstream of the hydrogen-sensitive RCS catalyst, or downstream thereof, or even be integrated into it in order to simultaneously carry out the filtration of particles and the NOx reduction reaction. This is then referred to as an RCS filter, or FRCS.

[0062] The hydrogen internal combustion engine installation according to the invention is particularly suitable for an on-board application, for example within a vehicle: heavy goods vehicle, ship, construction equipment, hovercraft, etc.

[0063] The control method according to the invention may have the following steps - degassing hydrogen is captured from the or at least one of the cryogenic tanks of the internal combustion engine, by means of the hydrogen capture line; and - at least part of the captured degassing hydrogen is injected into the exhaust line to treat the NOx in association with the hydrogen-sensitive selective reduction catalysis means and / or into the intake line as fuel.

[0064] The control method may further comprise at least one of the following steps (in particular depending on the embodiment variant of the internal combustion engine installation): - at least part of the captured hydrogen is injected into the intake line, for the recycling of part of the captured degassing hydrogen, - the quantity of NOx in the exhaust line is measured or estimated, in order to adapt the control to the quantity of NOx in the exhaust line, this measurement or estimation being able to be carried out at several points in the exhaust line, preferably upstream or downstream of each means of selective NOx reduction catalysis, - the temperature of the exhaust gases is measured or estimated, to adapt the control to the quantity of NOx in the exhaust line, - the quantity of hydrogen injected into the exhaust line is determined / controlled, where appropriate depending on the quantity of NOx in the exhaust line estimated or measured, for efficient operation of the RCS catalyst, - NOx is treated in the exhaust line with a selective reduction catalysis means sensitive to ammonia, and ammonia is injected into the exhaust line, for a significant reduction of NOx over a wide temperature range, - degassing hydrogen is injected into the exhaust line to ensure a sufficient quantity of hydrogen for the RCS catalysis, supplementing if necessary with additional hydrogen.

[0065] For example, the control method may implement the following steps: - if the quantity of hydrogen degassed from the cryogenic tank is greater than the quantity required to carry out the NOx reduction reaction, then the excess part is recycled to the intake of the heat engine, so that the hydrogen contained in them is burned in the combustion chamber, and produces work, and - on the contrary, if the quantity of degassing hydrogen is less than the quantity required to carry out the NOx reduction reaction, a supplementary supply of hydrogen may be injected additionally into the exhaust line, upstream of the RCS catalyst, for example by using an additional hydrogen injector and / or by using hydrogen from the recycling of crankcase gases (so-called "blow-by" gas).

[0066] Furthermore, for the embodiment for which the installation comprises a hydrogen-sensitive RCS catalyst and an ammonia-sensitive RCS catalyst, the method may comprise the following steps: - for an exhaust gas temperature below 150°C, the NOx in the exhaust line is treated using the hydrogen-sensitive RCS catalyst, - for an exhaust gas temperature above 150°C, the NOx in the exhaust line is treated using the ammonia-sensitive RCS catalyst.

[0067] [Fig.l] illustrates, schematically and in a non-limiting manner, a portion of installation (exhaust) of a hydrogen internal combustion engine according to a first embodiment of the invention.

[0068] The hydrogen internal combustion engine installation comprises an internal combustion engine (not shown). The internal combustion engine is supplied with air and fuel. The exhaust gases from the internal combustion engine are discharged through the exhaust line 1.

[0069] The hydrogen internal combustion engine comprises a supply of gaseous hydrogen (not shown) from a tank 2 for storing liquefied hydrogen, called cryogenic. This supply of hydrogen can be carried out directly in the combustion chamber of the engine or in the intake line 4. To extract the liquid hydrogen from the tank, it is known to equip the cryogenic tank with a hydrogen extraction line and to associate one or more heat exchangers therewith, in particular. For an example with two tanks, reference may be made to patent application US 2023 / 0375134.

[0070] In addition, the internal combustion engine installation comprises a line 3 for capturing degassing hydrogen (“boil-off”) from the ceiling 2' of the tank 2. The degassing hydrogen is distributed either in the exhaust line 1 (line 3') or in the intake line 4 (line 3”), respectively by means of a three-way valve VL. The exhaust line 1 comprises a hydrogen-sensitive selective NOx reduction catalysis device SCR-1. The capture line 3' injects, under the control of a pilot-controlled valve V2, the degassing hydrogen into the exhaust line 1 at a junction point 5 upstream of the hydrogen-sensitive selective NOx reduction catalysis device SCR-1. In addition, the exhaust line 1 comprises a hydrogen injector 6. The hydrogen injection 6 can be connected (not shown) to the hydrogen tank 2 allowing the hydrogen supply to the internal combustion engine.

[0071] The hydrogen internal combustion engine installation further comprises several sensors, including here three NOx probes arranged on the exhaust line 1. A first probe S1 is provided upstream of the hydrogen-sensitive selective NOx reduction catalysis device SCR-1 in order to determine the quantity of NOx to be treated, a second NOx probe S2 is provided downstream of the hydrogen-sensitive selective NOx reduction catalysis device SCR-1 in order to determine the NOx conversion efficiency in this device, and a third NOx probe S3 is provided downstream of the second ammonia-operated selective NOx reduction catalysis device SCR-2, in order to determine the efficiency of the latter, and the overall effectiveness of both SCR-1 and SCR-2 devices.

[0072] [Fig. 2] illustrates, schematically and in a non-limiting manner, a portion of a hydrogen internal combustion engine installation according to a second embodiment of the invention. The elements / fluids / components identical to the first embodiment of [Fig. 1] are not described again.

[0073] Compared to the first embodiment of [Fig.l], the installation provides an additional collection line 7 for residual hydrogen present within the casing 8 of the internal combustion engine (“blow-by”), and the exhaust line 1 is equipped with an optional pressure reducing member arranged at the junction point 10 between this additional collection line 7 and the exhaust line 1.

[0074] This additional capture line 7 is provided to evacuate the residual hydrogen within the crankcase 8. This capture line 7 comprises a set of pipes, and a de-oiling system 9 to separate the hydrogen from the oil coming from the crankcase. Such a de-oiling system can in particular be carried out, in a known manner by passive mechanical systems (not shown) of the baffle type, or by active systems (not shown), more efficient, based for example on the centrifugation of the oil (for example cyclone de-oilers or centrifugal separators), or a combination of passive and active systems.

[0075] This additional collection line 7 can also optionally include a gas pump.

[0076] As in the case of the degassing hydrogen capture line 3, the crankcase hydrogen capture line 7, downstream of the deoiling system 9 (an oil centrifuge for example), is equipped with a three-way valve V3 similar to the valve VI and making it possible to send this hydrogen upstream of the SCR-1 device (line 7' equipped with a controlled valve V4) and / or towards the inlet 4 (line 7”).

[0077] A first optional non-return valve C1 has also been provided on the capture line 3 of the “boil-off” hydrogen 3 between the tank 2 and the valve VI (which can naturally also be present in the first embodiment), and a second optional non-return valve C2 on the capture line 7 of the “blow-by” hydrogen between the casing 8 and the de-oiling system 9.

[0078] An optional pressure sensor S4 is also provided in the cryogenic tank 2 (again, which can also be present in the first embodiment), and a hydrogen sensor S4 at the engine casing 8.

[0079] In this second embodiment, we see that the hydrogen consumption of the installation is further optimized (that of the engine and / or that of the pollution control devices operating in the presence of a reducer), by being able to reuse both the degassing hydrogen from the tanks and the residual hydrogen from the crankcase: we also gain flexibility, depending on the availability of “blow-by”, “boil-off” and the needs of the hydrogen-sensitive catalytic device.

[0080] The invention also improves the safety of the installation, both at the level of the cryogenic tank and the engine casing.

[0081] Note that the sensors mentioned (NOx, hydrogen, temperature, pressure, etc.), particularly in view of the figures, are optional, can be moved on the installation, or even supplemented by other sensors and can in particular be, in whole or in part, replaced by estimates.

[0082] It should be noted that the valve system and their proposed control can be adapted / modified, in a manner known in the field, and that the relative positioning of the degassing hydrogen inlet and the hydrogen inlet from the crankcase can also be modified, when its recycling is provided, both in the exhaust line and in the intake line, if applicable.

Claims

Claims

1. Internal combustion engine installation using partially or totally hydrogen as fuel, said installation comprising an internal combustion engine, said engine being - in fluid connection, upstream, with an intake line (4) supplied with fuel including hydrogen coming from at least one tank (2) of liquid hydrogen, - in fluid connection, downstream, with an exhaust line (1) comprising at least one hydrogen-sensitive selective NOx reduction catalysis device (SCR-1), characterized in that said installation also comprises a degassing hydrogen capture line (3) for capturing the degassing hydrogen from the or at least one of the liquid hydrogen tanks, said hydrogen capture line being in fluid connection - with the exhaust line (1) upstream of the hydrogen-sensitive selective NOx reduction catalysis device (SCR-1) - and / or with the intake line (4).

2. Installation according to the preceding claim, characterized in that the or at least one of the liquid hydrogen tanks (2) is equipped with a degassing device, comprising in particular at least one degassing valve, said degassing device being in fluid connection with the degassing hydrogen collection line (3).

3. Installation according to one of the preceding claims, characterized in that it comprises at least one device for controlling the distribution of the portion of the hydrogen captured from the capture line which is injected into the exhaust line and of the portion of the hydrogen captured from the capture line which is injected into the intake line as a function of the hydrogen requirements of the hydrogen-sensitive selective NOx reduction catalysis device.

4. Installation according to the preceding claim, characterized in that the control device comprises at least one valve (VI, V2) on the degassing hydrogen capture line (3) which is controlled by computer / electronic means of the computer or calculator type.

5. Installation according to one of the preceding claims, characterized in that the exhaust line (1) comprises at least one NOx probe, preferably a first NOx probe (SI) upstream of said selective NOx reduction catalysis device sensitive to hydrogen and a second NOx probe (S2) downstream of said hydrogen-sensitive selective NOx reduction catalysis device.

6. Installation according to one of the preceding claims, characterized in that said exhaust line further comprises at least one hydrogen injector (6) upstream of the hydrogen-sensitive selective NOx reduction catalysis device (SCR-1).

7. Installation according to one of the preceding claims, characterized in that the exhaust line (1) comprises at least one selective NOx reduction catalysis device sensitive to ammonia (SCR-2).

8. Installation according to the preceding claim, characterized in that the ammonia-sensitive selective NOx reduction catalysis device (SCR-2) is arranged in the exhaust line upstream or downstream of the hydrogen-sensitive selective NOx reduction catalysis device (SCR-1).

9. Installation according to one of the preceding claims, characterized in that it comprises a line (7) for capturing the hydrogen present within a casing (8) of said internal combustion engine with a de-oiling system (9), said line (8) for capturing the hydrogen present within said casing being in fluid connection with the exhaust line (1) upstream of the hydrogen-sensitive selective NOx reduction catalysis device (SCR-1) and / or with the intake line (4).

10. Method for controlling a hydrogen internal combustion engine installation according to one of the preceding claims, characterized in that it implements the following steps: - hydrogen is captured during the degassing of the liquid hydrogen tank(s) (2) in the hydrogen capture line (3) - at least a portion of the degassing hydrogen captured from the degassing hydrogen capture line (3) is injected into the exhaust line (1) to treat the NOx in association with the hydrogen-sensitive selective NOx reduction catalysis device (SCR-1), and / or - at least a portion of the hydrogen captured from the capture line (3) is injected into the intake line (4).

11. Control method according to the preceding claim, characterized in that - residual hydrogen present in the crankcase is also captured engine (8) in a hydrogen capture line (7) from said crankcase - at least a portion of the residual hydrogen captured from the hydrogen capture line (7) from the crankcase (8) is injected into the exhaust line (1) to treat the NOx in association with the hydrogen-sensitive selective NOx reduction catalysis device (SCR-1), and / or - at least a portion of the hydrogen captured from the hydrogen capture line (7) from the crankcase (8) is injected into the intake line (4).

12. Control method according to claim 10 or 11, characterized in that the distribution of the portion of the hydrogen captured from the degassing hydrogen capture line (3) which is injected into the exhaust line (1) and the portion of the hydrogen captured from the capture line which is injected into the intake line (4) is controlled according to the hydrogen requirements of the hydrogen-sensitive selective NOx reduction catalysis device (SCR-1).

13. Land, sea or air vehicle characterized in that it comprises the installation according to one of claims 1 to 9.

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