JP2023061517A - engine system - Google Patents

Abstract

To provide an engine system capable of shortening a start time of an engine.SOLUTION: An engine system 1 includes: a main throttle valve 6 controlling a flow rate of air to be supplied to an ammonia engine 2; a main injector 5 supplying ammonia gas to the ammonia engine 2; a reformer 12 generating reformed gas; a reforming throttle valve 14 controlling a flow rate of air to be supplied to the reformer 12; a reforming injector 15 supplying ammonia gas to the reformer 12; a combustor 30 generating combustion gas for heating a reforming catalyst 22 of the reformer 12; a combustion injector 33 supplying ammonia gas to the combustor 30; and a controller 40 controlling the combustion injector 33 so that ammonia gas is supplied to the combustor 30 and the ammonia gas is burned with an air-fuel ratio rich in the combustor 30 at start of the ammonia engine 2.SELECTED DRAWING: Figure 1

Description

The present invention relates to engine systems.

BACKGROUND ART As a conventional engine system, a technique such as that described in Patent Document 1, for example, is known. The engine system described in Patent Document 1 includes an engine body, an intake branch pipe connected to an intake port of each cylinder of the engine body, and an ammonia injection valve that injects ammonia toward each engine intake passage of the engine body. , a hydrogen generator that generates hydrogen from liquid ammonia, and a hydrogen injection valve that injects hydrogen toward each engine intake passage of the engine body. The hydrogen generator consists of a tank in which liquid ammonia is stored, an evaporator that heats and vaporizes the liquid ammonia, and a supply in which part of the gaseous ammonia generated by this evaporator flows toward the ammonia injection valve. A pipe, a decomposer that decomposes gaseous ammonia produced by the evaporator, an inflow pipe through which air supplied to the decomposer flows, and a supply pipe through which hydrogen produced by the decomposer flows toward the hydrogen injection valve. and an electric heater for heating the catalyst of the cracker.

JP 2014-211155 A

However, the above conventional technology has the following problems. That is, the temperature of the catalyst rises by heating the catalyst of the decomposer with the electric heater. Then, when the temperature of the catalyst reaches the reformable temperature (activation temperature), hydrogen is produced by the cracker. Then, ammonia is mixed with hydrogen and combusted in the main body of the engine (engine). Since it takes time for the temperature of the cracker catalyst to reach the activation temperature, it takes a long time for hydrogen to be generated from the cracker. As a result, the engine starting time becomes longer.

SUMMARY OF THE INVENTION An object of the present invention is to provide an engine system capable of shortening the engine starting time.

An engine system according to an aspect of the present invention includes an engine in which fuel is combusted together with hydrogen, an intake passage through which air supplied to the engine flows, and an intake passage disposed in the intake passage to control the flow rate of the air supplied to the engine. A reformer that has a first flow control valve, a first fuel supply valve that supplies fuel to the engine, and a catalyst that decomposes the fuel into hydrogen, and that reforms the fuel to generate a hydrogen-containing reformed gas. an air flow path through which air supplied to the reformer flows; a second flow control valve disposed in the air flow path for controlling the flow rate of the air supplied to the reformer; a second fuel supply valve that supplies a second fuel supply valve, a reformed gas flow path through which the reformed gas produced by the reformer flows toward the engine, and a reformer connected to the reformer to generate combustion gas for heating the catalyst a combustor, an air flow path that connects the combustor, a branch flow path through which air supplied to the combustor flows, a third fuel supply valve that supplies fuel to the combustor, and a third fuel supply valve that supplies fuel to the combustor when the engine is started a start control unit that controls the first flow control valve, the first fuel supply valve, the second flow control valve, the second fuel supply valve, and the third fuel supply valve; Also, the third fuel supply valve is controlled so that the fuel burns in the combustor with a rich air-fuel ratio.

In such an engine system, first, air flows from the air flow path through the branch flow path and is supplied to the combustor, and fuel is supplied to the combustor by the third fuel supply valve. burns. At this time, by controlling the third fuel supply valve so that the fuel burns in the combustor with a rich air-fuel ratio, thermal decomposition of the fuel occurs and hydrogen is produced. Hydrogen produced by the combustor flows through the reformer and the reformate flow path to be supplied to the engine. After that, the catalyst of the reformer is heated by the combustion gas generated in the combustor, and the temperature of the catalyst rises. supplied. Then, when the temperature of the catalyst reaches the reformable temperature (activation temperature), reformed gas containing hydrogen is generated in the reformer, and the reformed gas flows through the reformed gas flow path and is supplied to the engine. Further, fuel and air are supplied to the engine by the first fuel supply valve and the first flow control valve, so that the fuel is mixed with hydrogen and combusted in the engine. By generating hydrogen in the combustor before hydrogen is generated in the reformer in this way, the amount of hydrogen required for starting the engine can be obtained quickly. This shortens the engine start-up time.

The start control unit supplies fuel to the combustor and supplies the fuel to the reformer while controlling the third fuel supply valve so that the fuel is burned in the combustor in a rich air-fuel ratio state. Even if the second flow control valve is controlled so that the flow rate of air is equal to or less than the specified value, and then the second flow control valve is controlled so that the flow rate of air supplied to the reformer is greater than the specified value. good.

With such a configuration, while the fuel is burning in the combustor with a rich air-fuel ratio, the flow rate of the air supplied to the reformer is suppressed. increases, the hydrogen produced by the combustor is less likely to be burned in the reformer. Therefore, the hydrogen produced by the combustor is less likely to be consumed, thereby further shortening the start-up time of the engine.

The start control unit supplies fuel to the combustor and controls the third fuel supply valve so that the fuel burns in the combustor with a rich air-fuel ratio, and then stops the supply of fuel to the combustor. The third fuel supply valve may be controlled as follows.

In such a configuration, after the temperature of the catalyst of the reformer is raised to a desired temperature by the combustion gas generated in the combustor, the third fuel supply valve is closed. Wasteful supply of fuel is prevented.

The engine system further includes a third flow control valve disposed in the branch flow path and controlling the flow rate of the air supplied to the reformer, the branch flow path being more dense than the second flow control valve in the air flow path. The start control unit connects the upstream side and the combustor, and controls the third fuel supply valve and the third fuel supply valve so that fuel and air are supplied to the combustor and the fuel burns in the combustor at a rich air-fuel ratio. After controlling the flow control valve, the third fuel supply valve and the third flow control valve may be controlled such that the supply of fuel and air to the combustor is stopped.

With such a configuration, the flow rate of air supplied to the combustor can be finely controlled by the third flow control valve. Therefore, it is possible to easily perform a control operation to make the air-fuel ratio rich in the combustor.

The start control unit determines whether or not a specified time has elapsed since the start of control of the third fuel supply valve so that the fuel is supplied to the combustor and the fuel is burned in the combustor with a rich air-fuel ratio. The third fuel supply valve may be controlled so that the supply of fuel to the combustor is stopped after a specified period of time has elapsed.

With such a configuration, the third fuel supply valve can be closed when the catalyst of the reformer is heated to a desired temperature by the combustion gas generated in the combustor without using a sensor or the like. can.

According to the present invention, it is possible to shorten the engine start-up time.

1 is a schematic configuration diagram showing an engine system according to one embodiment of the present invention; FIG. FIG. 2 is a flow chart showing the procedure of control processing executed by the controller shown in FIG. 1; FIG. 4 is a graph showing an example of the relationship between the air-fuel ratio and the amount of _H2 produced, the amount of NO produced, and the amount of residual _NH3 ; 2 is a timing diagram showing the operation of the engine system shown in FIG. 1; FIG. FIG. 4 is a diagram showing a comparison of the timings at which combustion gas and hydrogen are generated when ammonia gas is burned in a combustor with air-fuel ratios of lean and rich. 4 is a graph showing a comparison of changes over time in the temperature of combustion gas and the rotation speed of an ammonia engine when ammonia gas is burned in a combustor with air-fuel ratios of lean and rich.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing an engine system according to one embodiment of the present invention. In FIG. 1, an engine system 1 of this embodiment is mounted on a vehicle (not shown). The engine system 1 includes an ammonia engine 2 , an intake passage 3 , an exhaust passage 4 , a main injector 5 and a main throttle valve 6 .

The ammonia engine 2 is an engine that uses ammonia gas ( _NH3 gas) as fuel. In the ammonia engine 2 , hydrogen (H ₂ ) is mixed with the ammonia gas as a combustion aid in order to make the flame-retardant ammonia gas combustible. The ammonia engine 2 has a combustion chamber (not shown) in which ammonia gas is combusted together with hydrogen to generate exhaust gas. The ammonia engine 2 is, for example, a 4-cylinder engine.

The intake passage 3 is connected to the combustion chamber of the ammonia engine 2 . The intake passage 3 is a passage through which air supplied to the ammonia engine 2 flows. An air cleaner 7 is provided in the intake passage 3 to remove foreign matter such as dust contained in the air.

The exhaust passage 4 is connected with the combustion chamber of the ammonia engine 2 . The exhaust passage 4 is a passage through which the exhaust gas generated by the ammonia engine 2 flows. In the exhaust passage 4, a three-way catalyst 8 for purifying harmful components contained in the exhaust gas such as carbon monoxide (CO), unburned hydrocarbons (HC) and nitrogen oxides (NOx), and an SCR catalyst 9 for removing NOx contained in the air.

The main injector 5 is an electromagnetic fuel injection valve that injects ammonia gas toward the combustion chamber of the ammonia engine 2 . The main injector 5 constitutes a first fuel supply valve that supplies ammonia gas to the ammonia engine 2 . The main injectors 5 are provided as many as the cylinders of the ammonia engine 2 .

A main throttle valve 6 is arranged in the intake passage 3 . The main throttle valve 6 is an electromagnetic first flow control valve that controls the flow rate of air supplied to the ammonia engine 2 .

The engine system 1 also includes an ammonia cylinder 10, a vaporizer 11, a reformer 12, an air flow path 13, a reforming throttle valve 14, a reforming injector 15, a reformed gas flow path 16, A cooler 17 and a flow control valve 18 are provided.

The ammonia cylinder 10 is a container that stores ammonia in a liquid state. That is, the ammonia cylinder 10 stores liquid ammonia.

The vaporizer 11 vaporizes the liquid ammonia stored in the ammonia cylinder 10 to generate ammonia gas. Ammonia gas generated in the vaporizer 11 flows through the ammonia flow path 19 and is supplied to the main injector 5 , and also flows through the ammonia flow path 20 and is supplied to the reforming injector 15 .

The reformer 12 generates reformed gas containing hydrogen by reforming the ammonia gas using the heat generated by burning the ammonia gas. The reformer 12 has a cylindrical housing 21 and a reforming catalyst 22 housed in the housing 21 . The housing 21 is made of a metal material such as stainless steel having corrosion resistance against ammonia gas.

The reforming catalyst 22 has, for example, a honeycomb structure. The reforming catalyst 22 is a catalyst that burns ammonia gas and decomposes the ammonia gas into hydrogen. The reforming catalyst 22 is, for example, an ATR (Autothermal Reformer) type ammonia reforming catalyst. As the reforming catalyst 22, for example, a cobalt-based catalyst, a rhodium-based catalyst, a ruthenium-based catalyst, a palladium-based catalyst, or the like is used.

The air flow path 13 connects the intake passage 3 and the reformer 12 . One end of the air flow path 13 is branched and connected between the air cleaner 7 and the main throttle valve 6 in the intake passage 3 . The other end of the air flow path 13 is connected to the inlet of the housing 21 of the reformer 12 . The air flow path 13 is a flow path through which air supplied to the reformer 12 flows.

A reforming throttle valve 14 is arranged in the air flow path 13 . The reforming throttle valve 14 is an electromagnetic second flow control valve that controls the flow rate of air supplied to the reformer 12 .

The reforming injector 15 is an electromagnetic fuel injection valve that injects ammonia gas into the air flow path 13 . The reforming injector 15 injects ammonia gas between the reforming throttle valve 14 and the reformer 12 in the air flow path 13 . The reforming injector 15 constitutes a second fuel supply valve that supplies ammonia gas to the reformer 12 . The number of reforming injectors 15 may be plural (here, two) or one.

The reformed gas flow path 16 connects the reformer 12 and the intake passage 3 . One end of the reformed gas flow path 16 is connected to the outlet of the housing 21 of the reformer 12 . The other end of the reformed gas flow path 16 is connected between the main throttle valve 6 and the ammonia engine 2 in the intake passage 3 . The reformed gas flow path 16 is a flow path through which the reformed gas produced by the reformer 12 flows toward the ammonia engine 2 .

The cooler 17 is arranged in the reformed gas flow path 16 . The cooler 17 cools the reformed gas flowing through the reformed gas flow path 16 using, for example, engine cooling water for cooling the ammonia engine 2 .

The flow control valve 18 is arranged downstream of the cooler 17 in the reformed gas flow path 16 . The flow rate adjustment valve 18 is an electromagnetic valve that adjusts the flow rate of the reformed gas supplied to the ammonia engine 2 . An on-off valve (ON/OFF valve) may be used instead of the flow control valve 18 .

The engine system 1 also includes a combustor 30 , a branch flow path 31 , a combustion throttle valve 32 and a combustion injector 33 .

Combustor 30 is connected to reformer 12 . The combustor 30 generates combustion gas for heating the reforming catalyst 22 of the reformer 12 . The combustor 30 is, for example, a tubular flame burner that ignites and burns ammonia gas in a swirling state.

The combustor 30 has a cylindrical housing 34 and a spark plug 35 . The housing 34 is connected to the upstream portion of the housing 21 of the reformer 12 via a connecting portion 36 . The housing 34 and the connecting portion 36 are made of the same material as the housing 21 . The connecting portion 36 is provided in the downstream portion of the housing 34 . The ignition plug 35 ignites the ammonia gas inside the housing 34 . The spark plug 35 is arranged at the upstream end of the housing 34 .

The branch channel 31 connects the air channel 13 and the combustor 30 . One end of the branch channel 31 is branched and connected upstream of the reforming throttle valve 14 in the air channel 13 . The other end of branch flow path 31 is connected to an upstream portion of housing 34 of combustor 30 . The branch flow path 31 is a flow path through which air supplied to the combustor 30 flows.

A combustion throttle valve 32 is arranged in the branch flow path 31 . The combustion throttle valve 32 is an electromagnetic third flow control valve that controls the flow rate of air supplied to the combustor 30 .

Combustion injector 33 is connected to ammonia channel 19 via ammonia channel 37 . The ammonia flow path 37 is a flow path through which the ammonia gas generated by the vaporizer 11 flows.

The combustion injector 33 is an electromagnetic fuel injection valve that injects ammonia gas into the branch flow path 31 . The combustion injector 33 injects ammonia gas between the combustion throttle valve 32 and the combustor 30 in the branch flow path 31 . The combustion injector 33 constitutes a third fuel supply valve that supplies ammonia gas to the combustor 30 . The number of combustion injectors 33 may be plural (here, two) or one.

The engine system 1 also includes a controller 40 . The controller 40 includes a CPU, RAM, ROM, input/output interface, and the like. The controller 40 controls the ignition of the main injector 5 , the main throttle valve 6 , the reforming throttle valve 14 , the reforming injector 15 , the flow control valve 18 , the combustion throttle valve 32 , the combustion injector 33 and the combustor 30 when the ammonia engine 2 is started. It constitutes a starting control section that controls the plug 35 .

The controller 40 controls the combustion injector 33 so that ammonia gas is supplied to the combustor 30 and the ammonia gas is combusted in the combustor 30 with a rich air-fuel ratio.

At this time, the controller 40 controls the combustion injector 33 and the combustion throttle valve 32 so that the ammonia gas and air are supplied to the combustor 30 and the ammonia gas is burned in the combustor 30 at a rich air-fuel ratio, After that, the combustion injector 33 and combustion throttle valve 32 are controlled so that the supply of ammonia gas and air to the combustor 30 is stopped.

Further, while the controller 40 controls the combustion injector 33 so that the ammonia gas is supplied to the combustor 30 and the ammonia gas is burned in the combustor 30 with a rich air-fuel ratio, the reformer 12 The reforming throttle valve 14 is controlled so that the flow rate of air supplied to the reformer 12 is equal to or less than a specified value, and then the reforming throttle valve 14 is controlled so that the flow rate of air supplied to the reformer 12 is greater than the specified value. to control.

Specifically, while the controller 40 controls the combustion injector 33 so that the ammonia gas is supplied to the combustor 30 and the ammonia gas is burned in the combustor 30 with a rich air-fuel ratio, The reforming throttle valve 14 is controlled so that the flow rate of the air supplied to the reformer 12 becomes zero, and then the reforming throttle valve 14 is controlled so that air is supplied to the reformer 12 .

FIG. 2 is a flowchart showing the procedure of control processing executed by the controller 40. As shown in FIG. This processing is executed when an ignition switch (not shown) of the vehicle is turned on.

Before this process is executed, the main injector 5, the main throttle valve 6, the reforming throttle valve 14, the reforming injector 15, the flow control valve 18, the combustion throttle valve 32, and the combustion injector 33 are all closed. ing.

In FIG. 2, the controller 40 first controls to open the flow control valve 18 (step S101). The controller 40 also controls the main throttle valve 6 to open (step S102). Air is thereby supplied to the ammonia engine 2 . Further, the controller 40 controls to open the reforming injector 15 (step S103). Thereby, ammonia gas is supplied to the reformer 12 .

Further, the controller 40 controls to open the combustion throttle valve 32 and the combustion injector 33 (step S104). Air and ammonia gas are thereby supplied to the combustor 30 .

At this time, the controller 40 controls the combustion throttle valve 32 and the combustion injector 33 so that the ammonia gas is burned in the combustor 30 with a rich air-fuel ratio. The state in which the air-fuel ratio is rich, as shown in FIG. 3, is a state in which the ratio of ammonia gas is greater than the stoichiometric air-fuel ratio (stoichiometric: λ=1.0). The state in which the air-fuel ratio is lean is a state in which the ratio of ammonia gas is less than the stoichiometric air-fuel ratio.

In the graph shown in FIG. 3, the horizontal axis indicates the air-fuel ratio (λ), and the vertical axis indicates the amount of gas. The solid line P indicates the amount of _H2 produced, the dashed line Q indicates the amount of NO produced, and the dashed-dotted line R indicates the amount of unburned _NH3 remaining. On the rich side of the stoichiometric air-fuel ratio, the amount of _H2 produced is greater than the amount of NO produced, and the amount of unburned _NH3 remaining increases rapidly. Note that FIG. 3 shows calculated values when ammonia gas is burned at normal temperature and normal pressure.

Then, the controller 40 turns ON the ignition plug 35 of the combustor 30 (step S105). As a result, the ammonia gas is ignited and burned in the combustor 30 to generate combustion gas, and the reforming catalyst 22 of the reformer 12 is heated by the combustion gas.

After that, the controller 40 determines whether or not a specified time has passed since the control to open the combustion throttle valve 32 and the combustion injector 33 in step S104 (step S106). The prescribed time is, for example, the time required for the reforming catalyst 22 of the reformer 12 to reach a combustible temperature, and is set in advance through experiments or the like. The combustible temperature is the temperature at which the reforming catalyst 22 can burn the ammonia gas.

When the controller 40 determines that the specified time has elapsed, the controller 40 turns off the ignition plug 35 of the combustor 30 (step S107). As a result, the combustion gas is stopped from being generated in the combustor 30 .

The controller 40 then controls the combustion throttle valve 32 and the combustion injector 33 to close (step S108). This stops the supply of air and ammonia gas to the combustor 30 .

Further, the controller 40 controls to open the reforming throttle valve 14 (step S109). Air is thereby supplied to the reformer 12 . Then, the controller 40 controls to open the main injector 5 (step S110). Thereby, ammonia gas is supplied to the ammonia engine 2 .

In the engine system 1 as described above, when an ignition switch (not shown) of the vehicle is turned on, the flow control valve 18 opens to a specified degree of opening (see FIG. 4(a)).

Air is supplied to the ammonia engine 2 by opening the main throttle valve 6 to a specified degree of opening (see FIG. 4(b)). Further, the ammonia gas is supplied to the reformer 12 by opening the reforming injector 15 so that the reforming injector 15 injects a prescribed value of ammonia gas (see FIG. 4(h)).

Further, the combustion throttle valve 32 is opened to a specified opening degree (see FIG. 4D), and the combustion injector 33 is opened so that a specified value of ammonia gas is injected from the combustion injector 33 (FIG. 4). (e)), air and ammonia gas are supplied to the combustor 30 . At this time, the combustion throttle valve 32 and the combustion injector 33 are opened so that the air-fuel ratio in the combustor 30 becomes rich.

Further, when the ignition plug 35 of the combustor 30 is turned on (see FIG. 4(f)), the ammonia gas is ignited and burned. Specifically, as shown in the following formula, ammonia and oxygen in the air chemically react to generate high-temperature combustion gas (exothermic reaction).
_NH3 +3/ _4O2- >1/ _2N2 +3/ _2H2O ...(A)

Combustion gas is supplied from combustor 30 to reformer 12 through connection 36 . Then, the reforming catalyst 22 of the reformer 12 is heated by the heat of the combustion gas, and the temperature of the reforming catalyst 22 rises. Then, when the specified time T elapses after the combustion throttle valve 32 and the combustion injector 33 are opened, the temperature of the reforming catalyst 22 reaches the combustible temperature.

When the temperature of the reforming catalyst 22 reaches the combustible temperature, the spark plug 35 is turned off (see FIG. 4(f)). Also, the combustion throttle valve 32 and the combustion injector 33 are closed (see FIGS. 4D and 4E), thereby stopping the supply of air and ammonia gas to the combustor 30 . Thereby, the combustion of the ammonia gas in the combustor 30 ends.

Air is supplied to the reformer 12 by opening the reforming throttle valve 14 to a specified degree of opening (see FIG. 4(g)). As a result, the reforming catalyst 22 burns the ammonia gas, causing the exothermic reaction of the formula (A), and the self-heat of the reforming catalyst 22 further increases the temperature of the reforming catalyst 22 . When the temperature of the reforming catalyst 22 reaches the activation temperature (reforming temperature), the reforming catalyst 22 reforms the ammonia gas. Specifically, a cracking reaction of ammonia occurs (endothermic reaction) and a reformed gas containing hydrogen is generated as shown in the following formula.
_NH3 →3/ _2H2 +1/ _2N2 (B)

The reformed gas flows through the reformed gas flow path 16 and the intake passage 3 and is supplied to the ammonia engine 2 . Further, ammonia gas is supplied to the ammonia engine 2 by opening the valve of the main injector 5 so that the main injector 5 injects a specified value of ammonia gas (see FIG. 4(c)). Then, in the ammonia engine 2, the ammonia gas is combusted together with the hydrogen in the reformed gas. This completes the starting operation of the ammonia engine 2, and shifts to a steady state.

Here, when ammonia gas is burned in the combustor 30 with a lean air-fuel ratio (see FIG. 3), combustion gas is generated as shown in FIG. is less likely to occur, hydrogen is less likely to be generated. Therefore, hydrogen is not produced until the temperature of the reforming catalyst 22 of the reformer 12 reaches the activation temperature.

Therefore, at time t1 after the temperature of the reforming catalyst 22 reaches the activation temperature, the reformer 12 starts producing hydrogen. The hydrogen produced by the reformer 12 flows through the reformed gas flow path 16 and the intake passage 3 and is supplied to the ammonia engine 2 . Then, at the subsequent time t2, the amount of hydrogen required for starting the ammonia engine 2 is reached.

On the other hand, when ammonia gas is burned in the combustor 30 with a rich air-fuel ratio (see FIG. 3), as shown in FIG. Hydrogen is produced by pyrolysis of the gas. Hydrogen produced by the combustor 30 flows through the reformer 12 , the reformed gas flow path 16 and the intake passage 3 and is supplied to the ammonia engine 2 .

After that, the combustion of the ammonia gas is completed in the combustor 30, but at time t1 after the temperature of the reforming catalyst 22 reaches the activation temperature, the reformer 12 starts producing hydrogen. The hydrogen produced by the reformer 12 flows through the reformed gas flow path 16 and the intake passage 3 and is supplied to the ammonia engine 2 . At time t*, which is earlier than time t2, the amount of hydrogen required for starting the ammonia engine 2 is reached.

After hydrogen is generated by the combustor 30 in this way, hydrogen is generated by the reformer 12, so that the amount of hydrogen necessary for starting the ammonia engine 2 can be obtained quickly. This shortens the starting time of the ammonia engine 2 (see time t2→t* in FIG. 5).

FIG. 6 is a graph showing a comparison of changes over time in the temperature of the combustion gas and the rotation speed of the ammonia engine 2 when the ammonia gas is burned in the combustor 30 at lean and rich air-fuel ratios.

FIG. 6A shows experimental data when ammonia gas is burned in the combustor 30 at a lean air-fuel ratio (λ=1.13). In FIG. 6( a ), the dashed line Ma indicates the temperature of the combustion gas, and the solid line Na indicates the rotation speed of the ammonia engine 2 . Time ta is the time when the first combustion (initial explosion) occurred in the ammonia engine 2 .

FIG. 6B shows experimental data when ammonia gas is burned in the combustor 30 at a rich air-fuel ratio (λ=0.84). In FIG. 6(b), the dashed line Mb indicates the temperature of the combustion gas, and the solid line Nb indicates the rotation speed of the ammonia engine 2. As shown in FIG. Time tb is the time when the first combustion (initial explosion) occurred in the ammonia engine 2 .

As can be seen from FIG. 6, when the ammonia gas is burned in the combustor 30 with a rich air-fuel ratio, compared to the case where the ammonia gas is burned in the combustor 30 with a lean air-fuel ratio, The initial explosion timing of the ammonia engine 2 is advanced by (ta-tb) seconds.

As described above, according to the present embodiment, first, air flows from the air flow path 13 through the branch flow path 31 and is supplied to the combustor 30, and ammonia gas is supplied to the combustor 30 by the combustion injector 33. , the ammonia gas is burned in the combustor 30 . At this time, by controlling the combustion injector 33 so that the ammonia gas is burned in the combustor 30 with a rich air-fuel ratio, the ammonia gas is thermally decomposed to generate hydrogen. Hydrogen generated by the combustor 30 flows through the reformer 12 and the reformed gas flow path 16 and is supplied to the ammonia engine 2 . After that, the reforming catalyst 22 of the reformer 12 is heated by the combustion gas generated in the combustor 30, and the temperature of the reforming catalyst 22 rises. Ammonia gas and air are supplied to the qualityr 12 . Then, when the temperature of the reforming catalyst 22 reaches the reformable temperature (activation temperature), reformed gas containing hydrogen is generated in the reformer 12, and the reformed gas flows through the reformed gas passage 16 to produce ammonia. It is supplied to the engine 2. Further, ammonia gas and air are supplied to the ammonia engine 2 by the main injector 5 and the main throttle valve 6 , and the ammonia gas is mixed with hydrogen and combusted in the ammonia engine 2 . By generating hydrogen in the combustor 30 before hydrogen is generated in the reformer 12 in this manner, the amount of hydrogen required for starting the ammonia engine 2 can be obtained quickly. Thereby, the starting time of the ammonia engine 2 is shortened.

Further, in the present embodiment, while the ammonia gas is supplied to the combustor 30 and the combustion injector 33 is controlled so that the ammonia gas is burned in the combustor 30 with a rich air-fuel ratio, the reformer The reforming throttle valve 14 is controlled so that the flow rate of the air supplied to the reformer 12 is equal to or less than a specified value, and then the reforming throttle valve is controlled so that the flow rate of air supplied to the reformer 12 is greater than the specified value. 14 is controlled. In this case, while the ammonia gas is combusted in the combustor 30 with a rich air-fuel ratio, the flow rate of the air supplied to the reformer 12 is suppressed. Even if the temperature of the reforming catalyst 22 rises, the hydrogen produced by the combustor 30 is less likely to be burned in the reformer 12 . Therefore, the hydrogen generated by the combustor 30 is less likely to be consumed, so the starting time of the ammonia engine 2 is further shortened.

Further, in the present embodiment, after the ammonia gas is supplied to the combustor 30 and the combustion injector 33 is controlled so that the ammonia gas is burned in the combustor 30 with a rich air-fuel ratio, the ammonia gas is supplied to the combustor 30. The combustion injector 33 is controlled so that the supply of ammonia gas is stopped. In this case, after the reforming catalyst 22 of the reformer 12 is heated to a desired temperature by the combustion gas generated in the combustor 30, the combustion injector 33 is closed. wasteful supply of ammonia gas to the

Further, in the present embodiment, the combustion injector 33 and the combustion throttle valve 32 are controlled so that the ammonia gas and air are supplied to the combustor 30 and the ammonia gas is burned in the combustor 30 with a rich air-fuel ratio. After that, the combustion injector 33 and the combustion throttle valve 32 are controlled so that the supply of ammonia gas and air to the combustor 30 is stopped. In this case, the flow rate of air supplied to the combustor 30 can be finely controlled by the combustion throttle valve 32 . Therefore, the control operation for making the air-fuel ratio rich in the combustor 30 can be easily performed.

Further, in the present embodiment, the ammonia gas is supplied to the combustor 30 and the control of the combustion injector 33 is started so that the ammonia gas is burned in the combustor 30 at a rich air-fuel ratio. The combustion injector 33 is controlled so as to stop the supply of fuel to the combustor 30 when a prescribed time has elapsed. In this case, the combustion injector 33 is closed when the temperature of the reforming catalyst 22 of the reformer 12 is raised to a desired temperature by the combustion gas generated in the combustor 30 without using a sensor or the like. be able to.

In addition, this invention is not limited to the said embodiment. For example, in the above embodiment, while the ammonia gas is burned in the combustor 30 with a rich air-fuel ratio, the flow rate of the air supplied to the reformer 12 is zero, and then the air is supplied to the reformer 12. However, it is not particularly limited to such a form. A small amount of air may be supplied to the reformer 12 while the ammonia gas is combusted in the combustor 30 with a rich air-fuel ratio, and then the flow rate of the air supplied to the reformer 12 may be increased.

Further, in the above-described embodiment, when the reformed gas containing hydrogen is generated by the reformer 12 after the specified time has passed since the combustion throttle valve 32 and the combustion injector 33 are controlled to open, the main injector Ammonia gas is supplied to the ammonia engine 2 by opening the valve 5, but it is not particularly limited to such a form. For example, the main injector 5 may be opened when hydrogen is produced by the combustor 30 .

Further, in the above embodiment, the combustion throttle valve 32 and the combustion injector 33 are closed when the specified time has passed since the control was performed to open the combustion throttle valve 32 and the combustion injector 33. is not limited to any form. After the combustion throttle valve 32 and the combustion injector 33 are controlled to open, when the temperature sensor or the like detects that the temperature of the reformer 12 has reached a specified temperature (for example, a combustible temperature), the combustion throttle valve is opened. 32 and combustion injectors 33 may be closed.

In the above embodiment, the combustion throttle valve 32 and the combustion injector 33 are closed after the combustion throttle valve 32 and the combustion injector 33 are opened so that the ammonia gas is burned in the combustor 30 with a rich air-fuel ratio. Although it is valved, it is not specifically limited to such a form. For example, even after reformed gas is generated by the reformer 12, the combustion throttle valve 32 and the combustion injector 33 may remain open.

Further, in the above embodiment, the combustion throttle valve 32 is arranged in the branch flow path 31 connecting the air flow path 13 and the combustor 30, but such a combustion throttle valve 32 may be omitted.

Further, in the above embodiment, the reformer 12 has the reforming catalyst 22 having both the function of burning the ammonia gas and the function of decomposing the ammonia gas into hydrogen. Not limited. The reformer 12 may separately have a combustion catalyst for burning the ammonia gas and a reforming catalyst for decomposing the ammonia gas into hydrogen.

In the above embodiment, the combustor 30 is a tubular flame burner that ignites the ammonia gas in a swirling state. It is not limited to burners.

Further, in the above embodiment, ammonia gas is used as fuel, but the present invention is also applicable to engine systems that use hydrocarbons or the like as fuel.

REFERENCE SIGNS LIST 1 engine system 2 ammonia engine (engine) 3 intake passage 5 main injector (first fuel supply valve) 6 main throttle valve (first flow control valve) 12 reformer 13 Air flow path 14 Reforming throttle valve (second flow control valve) 15 Reforming injector (second fuel supply valve) 16 Reformed gas flow path 22 Reforming catalyst (catalyst) 30 Combustor 31 Branch channel 32 Combustion throttle valve (third flow control valve) 33 Combustion injector (third fuel supply valve) 40 Controller (starting control section).

Claims (5)

an engine in which the fuel is combusted with hydrogen;
an intake passage through which air supplied to the engine flows;
a first flow control valve disposed in the intake passage for controlling the flow rate of air supplied to the engine;
a first fuel supply valve that supplies the fuel to the engine;
a reformer having a catalyst for decomposing the fuel into the hydrogen and reforming the fuel to generate a reformed gas containing the hydrogen;
an air flow path through which air supplied to the reformer flows;
a second flow control valve disposed in the air flow path and controlling the flow rate of the air supplied to the reformer;
a second fuel supply valve that supplies the fuel to the reformer;
a reformed gas flow path through which the reformed gas generated by the reformer flows toward the engine;
a combustor connected to the reformer and generating combustion gas for heating the catalyst;
a branch flow path connecting the air flow path and the combustor and through which air supplied to the combustor flows;
a third fuel supply valve that supplies the fuel to the combustor;
A starting control unit that controls the first flow control valve, the first fuel supply valve, the second flow control valve, the second fuel supply valve, and the third fuel supply valve when the engine is started,
The engine system according to claim 1, wherein the starting control section controls the third fuel supply valve so that the fuel is supplied to the combustor and the fuel is burned in the combustor at a rich air-fuel ratio. While the start control unit controls the third fuel supply valve so that the fuel is supplied to the combustor and the fuel is burned in the combustor in a state where the air-fuel ratio is rich, The second flow control valve is controlled so that the flow rate of air supplied to the reformer is equal to or less than a specified value, and then the flow rate of air supplied to the reformer is made greater than the specified value. 2. The engine system according to claim 1, wherein the second flow control valve is controlled by The start control unit controls the third fuel supply valve so that the fuel is supplied to the combustor and the fuel is burned in the combustor with the air-fuel ratio being rich, and then the combustor 3. The engine system according to claim 1, wherein said third fuel supply valve is controlled so as to stop the supply of said fuel to said engine. further comprising a third flow control valve disposed in the branch flow path and controlling the flow rate of the air supplied to the reformer;
The branch flow path connects the upstream side of the second flow control valve in the air flow path and the combustor,
The start control unit controls the third fuel supply valve and the third flow rate so that the fuel and the air are supplied to the combustor and the fuel is burned in the combustor at a rich air-fuel ratio. 4. The engine system according to claim 3, wherein after controlling the control valves, the third fuel supply valve and the third flow control valve are controlled such that the supply of the fuel and the air to the combustor is stopped. The start-up control unit specifies after starting control of the third fuel supply valve so that the fuel is supplied to the combustor and the fuel is burned in the combustor in a state where the air-fuel ratio is rich. 5. An engine according to claim 3 or 4, wherein it is determined whether or not time has passed, and when said specified time has passed, said third fuel supply valve is controlled so as to stop the supply of said fuel to said combustor. system.

Images