JP2021173232A - Engine system - Google Patents

Abstract

To provide an engine system in which the oxidative degradation of a catalyst of a reformer caused by lack of fuel can be prevented.SOLUTION: An engine system 1 comprises: an ammonia tank 11 storing ammonia; a reformer 13 which has a reforming catalyst 13b for decomposing the ammonia to hydrogen using heat generated by combusting the ammonia, and creates a reformed gas containing the hydrogen by reforming the ammonia; a reforming injector 16 supplying the ammonia to the reformer 13; a reforming throttle valve 15 adjusting a flow volume of air supplied to the reformer 13; a pressure sensor 27 and a residual amount determination unit 31 detecting a residual amount of the ammonia in the ammonia tank 11; and a valve control unit 33 controlling the reforming throttle valve 15 in such a way that flow volume of air supplied to the reformer 13 is reduced when the residual amount of the ammonia in the ammonia tank 11 is equal to a specified amount or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to an engine system.

As a conventional engine system, for example, the technique described in Patent Document 1 is known. The engine system described in Patent Document 1 includes an engine main body, an engine intake passage and an engine exhaust passage connected to the combustion chamber of the engine main body, a throttle valve arranged inside the engine intake passage, and an engine intake passage. An ammonia injection valve that injects gaseous ammonia toward it, a tank that stores liquid ammonia, an evaporator that heats and vaporizes liquid ammonia, and a decomposer that decomposes gaseous ammonia with a catalyst to generate hydrogen. And the air supply pipe that is connected to the engine intake passage and supplies air to the decomposer, the outflow pipe that is connected to the engine intake passage and the gas containing hydrogen generated by the decomposer flows out, and the gaseous ammonia is evaporated. It is equipped with an ammonia supply pipe that supplies the ammonia injection valve from the vessel.

Japanese Unexamined Patent Publication No. 2014-21115

In the above-mentioned conventional technique, when the ammonia in the tank becomes empty, the engine stops due to running out of fuel. At this time, since the inside of the reformer is easily exposed to the oxidizing atmosphere due to the shortage of ammonia as a fuel, the catalyst of the reformer is deteriorated by oxidation especially at a high temperature.

An object of the present invention is to provide an engine system capable of preventing oxidative deterioration of a catalyst of a reformer due to running out of fuel.

The engine system according to one aspect of the present invention includes an engine, an intake passage through which air supplied to the engine flows, an exhaust passage through which exhaust gas generated from the engine flows, and an ammonia injection valve that injects ammonia toward the engine. , An air flow control valve that is installed in the intake passage and controls the flow rate of air supplied to the engine, an ammonia tank that stores ammonia, and the heat generated by burning ammonia is used to decompose ammonia into hydrogen. Ammonia is supplied to the reformer, an air flow path through which the air supplied to the reformer flows, and a reformer that reforms ammonia to generate a reformed gas containing hydrogen. Ammonia supply unit, air flow rate adjusting unit that is arranged in the air flow path and adjusts the flow rate of air supplied to the reformer, and reforming gas generated by the reformer flows toward the engine. A control unit including a gas flow path, a remaining amount detecting unit that detects the remaining amount of ammonia in the ammonia tank, and a control unit that controls an ammonia injection valve, an air flow rate control valve, an ammonia supply unit, and an air flow rate adjusting unit. Is an air flow rate adjusting unit that reduces the flow rate of air supplied to the reformer when the remaining amount of ammonia in the ammonia tank detected by the remaining amount detection unit is less than or equal to a predetermined specified amount. To control.

In such an engine system, when ammonia and air are supplied to the reformer and the engine, respectively, the reformer reforms the ammonia to generate a reformed gas containing hydrogen, and the reformed gas is supplied to the engine. Is supplied. Then, in the engine, ammonia burns together with hydrogen in the reformed gas. Since ammonia is consumed during the combustion operation of the engine, the remaining amount of ammonia in the ammonia tank gradually decreases. Therefore, the remaining amount detection unit detects the remaining amount of ammonia in the ammonia tank. At this time, when the remaining amount of ammonia in the ammonia tank is less than or equal to the specified amount, the air flow rate adjusting unit is controlled so that the flow rate of the air supplied to the reformer decreases. Therefore, the inside of the reformer is less likely to be exposed to the oxidizing atmosphere. Further, by reducing the flow rate of the air supplied to the reformer, the promotion of combustion of ammonia in the reformer is suppressed, so that the temperature rise of the reformer is suppressed. As described above, it is possible to prevent the reformer catalyst from being oxidatively deteriorated due to running out of fuel.

The remaining amount detecting unit may have a pressure sensor for detecting the residual pressure of ammonia in the ammonia tank, and may detect the remaining amount of ammonia from the residual pressure of ammonia. In such a configuration, by using the pressure sensor, the remaining amount of ammonia in the ammonia tank can be detected easily and inexpensively.

The engine system further includes a temperature detection unit that detects the temperature of the reformer, and the control unit controls the air flow rate adjusting unit so as to reduce the flow rate of the air supplied to the reformer, and then the temperature detection unit. When the temperature of the reformer detected by is below a predetermined specified temperature, the ammonia injection valve and the air flow control valve are controlled to be closed, and the supply of ammonia and air to the reformer is stopped. The ammonia supply unit and the air flow rate adjusting unit may be controlled. In such a configuration, when the temperature of the reformer becomes equal to or lower than the specified temperature, the supply of ammonia and air to the reformer is stopped, so that the reformer does not generate reformed gas. In addition, the supply of ammonia, air, and reforming gas to the engine is also stopped, so that the engine is stopped.

The engine system is further equipped with a notification unit for notifying that the remaining amount of ammonia in the ammonia tank detected by the remaining amount detection unit is close to empty when the remaining amount of ammonia in the ammonia tank is less than the specified amount. May be good. In such a configuration, the driver of the vehicle knows from the notification unit that the remaining amount of ammonia in the ammonia tank is small, and can move the vehicle to a safe place by manual driving.

According to the present invention, it is possible to prevent oxidative deterioration of the catalyst of the reformer due to running out of fuel.

It is a schematic block diagram which shows the engine system which concerns on one Embodiment of this invention. It is a block diagram which shows the structure of the control system of the engine system shown in FIG. It is a flowchart which shows the detail of the control processing procedure executed by the control unit shown in FIG. It is a graph which compares and shows the relationship between the supply flow rate of ammonia gas and air, and the temperature of a reforming catalyst for each state. It is a schematic block diagram which shows the modification of the engine system shown in FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or equivalent elements are designated by the same reference numerals, and duplicate description will be omitted.

FIG. 1 is a schematic configuration diagram showing an engine system according to an embodiment of the present invention. In FIG. 1, the engine system 1 of the present embodiment is mounted on an engine-type vehicle 10. The engine system 1 includes an ammonia engine 2, an intake passage 3, an exhaust passage 4, a plurality of (four in this case) main injectors 5, and a main throttle valve 6.

The ammonia engine 2 is an engine that uses _{ammonia (NH 3) as fuel.} The ammonia engine 2 is, for example, a 4-cylinder engine and has four combustion chambers 2a. _{Hydrogen (H 2} ) is supplied to the combustion chamber 2a together with ammonia. As a result, hydrogen is mixed with ammonia in the combustion chamber 2a, so that ammonia is easily burned.

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

The exhaust passage 4 is connected to the combustion chamber 2a. The exhaust passage 4 is a passage through which the exhaust gas generated from the combustion chamber 2a flows. An exhaust purification catalyst 8 for removing harmful substances contained in exhaust gas is arranged in the exhaust passage 4.

The main injector 5 is an electromagnetic type ammonia injection valve for injecting ammonia gas (NH ₃ gas) toward the combustion chamber 2a. The main injector 5 is connected to a vaporizer 12 described later via an ammonia gas flow path 9. The ammonia gas flow path 9 is a flow path through which ammonia gas flows. The main injector 5 is attached to the ammonia engine 2.

The main throttle valve 6 is arranged between the air cleaner 7 and the ammonia engine 2 in the intake passage 3. The main throttle valve 6 is an electromagnetic air flow rate control valve that controls the flow rate of air supplied to the ammonia engine 2.

Further, the engine system 1 includes an ammonia tank 11, a vaporizer 12, a reformer 13, an air flow path 14, a reforming throttle valve 15, a reforming injector 16, an electric heater 17, and a reforming gas. It includes a flow path 18, a reformed gas cooler 19, and a stop valve 20.

The ammonia tank 11 is a tank that stores ammonia in a liquid state. That is, the ammonia tank 11 stores liquid ammonia. The vaporizer 12 vaporizes the liquid ammonia stored in the ammonia tank 11 to generate ammonia gas.

The reformer 13 reforms the ammonia gas to generate a reformed gas containing hydrogen. The reformer 13 has, for example, a carrier 13a having a honeycomb structure and a reforming catalyst 13b applied to the carrier 13a.

The reforming catalyst 13b is a catalyst that decomposes ammonia gas into hydrogen by utilizing the heat generated by burning ammonia gas. The reforming catalyst 13b has a function of burning ammonia gas in addition to a function of decomposing ammonia gas into hydrogen. The reforming catalyst 13b is, for example, an ATR (Autothermal Reformer) type ammonia reforming catalyst. As the reforming catalyst 13b, 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 14 connects the intake passage 3 and the reformer 13. Specifically, one end of the air flow path 14 is branched and connected to a portion of the intake passage 3 between the air cleaner 7 and the main throttle valve 6. The other end of the air flow path 14 is connected to the reformer 13. The air flow path 14 is a flow path through which the air supplied to the reformer 13 flows.

The reforming throttle valve 15 is arranged in the air flow path 14. The reforming throttle valve 15 is an electromagnetic air flow rate adjusting unit that adjusts the flow rate of the air supplied to the reformer 13.

The reforming injector 16 is connected to the vaporizer 12 via an ammonia gas flow path 21. The ammonia gas flow path 21 is a flow path through which the ammonia gas generated by the vaporizer 12 flows. The reforming injector 16 is an electromagnetic fuel injection valve that injects ammonia gas toward the reformer 13. Specifically, the reforming injector 16 injects ammonia gas between the reforming throttle valve 15 and the reformer 13 in the air flow path 14. Therefore, air and ammonia gas flow through the portion of the air flow path 14 between the reforming throttle valve 15 and the reformer 13. The reforming injector 16 constitutes an ammonia supply unit that supplies ammonia gas to the reformer 13.

A pressure reducing valve 23 is provided in the ammonia gas flow path 21. The pressure reducing valve 23 decompresses the ammonia gas supplied to the ammonia engine 2 and the reformer 13 to maintain the pressure of the ammonia gas at a predetermined pressure.

The electric heater 17 heats the ammonia gas supplied to the reformer 13 to raise the temperature of the reformer 13. The electric heater 17 has a heating element 24 arranged in the air flow path 14 and a heater power supply 25 for energizing the heating element 24. The heating element 24 has, for example, a honeycomb structure. The heat of the ammonia gas heated by the electric heater 17 is transferred to the reformer 13, so that the temperature of the reformer 13 rises. The electric heater 17 may raise the temperature of the reformer 13 by directly heating the reformer 13.

The reforming gas flow path 18 connects the reformer 13 and the intake passage 3. Specifically, one end of the reforming gas flow path 18 is connected to the reformer 13. The other end of the reformed gas flow path 18 is branched and connected to a portion of the intake passage 3 between the main throttle valve 6 and the ammonia engine 2. The reformed gas flow path 18 is a flow path through which the reformed gas generated by the reformer 13 flows toward the ammonia engine 2.

The reformed gas cooler 19 is arranged in the reformed gas flow path 18. The reformed gas cooler 19 cools the reformed gas supplied to the ammonia engine 2. This prevents the intake system components such as the main throttle valve 6 from being damaged by heat. Further, since the volume expansion of the reformed gas is suppressed, air is sufficiently easily sucked into the combustion chamber 2a of the ammonia engine 2.

The stop valve 20 is arranged between the reformed gas cooler 19 and the intake passage 3 in the reformed gas flow path 18. The stop valve 20 is an electromagnetic on-off valve that opens and closes the reformed gas flow path 18.

Further, the engine system 1 includes a pressure sensor 27, a temperature sensor 28, a display 29, and a control unit 30.

The pressure sensor 27 is a sensor that detects the pressure in the ammonia tank 11. Specifically, the pressure sensor 27 detects the residual pressure of liquid ammonia in the ammonia tank 11.

The temperature sensor 28 is a temperature detection unit that detects the temperature of the reformer 13. The temperature sensor 28 detects, for example, the temperature of the reforming catalyst 13b of the reformer 13.

The display 29 displays the status of each part of the engine system 1. The display 29 displays, for example, the state of each part of the engine system 1 on the screen together with voice.

The control unit 30 is composed of a CPU, RAM, ROM, an input / output interface, and the like. The control unit 30 includes a main injector 5, a main throttle valve 6, a reforming throttle valve 15, a reforming injector 16, a stop valve 20, a heater power supply 25, and an indicator based on the detected values of the pressure sensor 27 and the temperature sensor 28. 29 is controlled.

As shown in FIG. 2, the control unit 30 includes a remaining amount determination unit 31, a display control unit 32, and a valve control unit 33.

The remaining amount determination unit 31 determines whether or not the remaining amount of liquid ammonia in the ammonia tank 11 is equal to or less than the specified amount based on the detection value of the pressure sensor 27, so that the remaining amount of liquid ammonia in the ammonia tank 11 remains. It is determined whether the amount is close to empty, that is, close to running out of fuel. The remaining amount determination unit 31 constitutes a remaining amount detecting unit that detects the remaining amount of liquid ammonia in the ammonia tank 11 in cooperation with the pressure sensor 27.

When the display control unit 32 determines that the remaining amount of liquid ammonia in the ammonia tank 11 is close to empty by the remaining amount determination unit 31, the display control unit 32 indicates that the remaining amount of liquid ammonia is close to empty. The display 29 is controlled so as to notify the notification. The display control unit 32 cooperates with the display unit 29 to empty the remaining amount of liquid ammonia when the remaining amount of liquid ammonia in the ammonia tank 11 detected by the remaining amount determination unit 31 is equal to or less than the specified amount. It constitutes a notification unit that notifies that the state is close to.

The valve control unit 33 constitutes a control unit that controls the main injector 5, the main throttle valve 6, the reforming throttle valve 15, the reforming injector 16, and the stop valve 20.

The valve control unit 33 reduces the flow rate of the air supplied to the reformer 13 when the remaining amount of liquid ammonia in the ammonia tank 11 detected by the remaining amount determination unit 31 is equal to or less than the specified amount. When the temperature of the reformer 13 detected by the temperature sensor 28 after controlling the reforming throttle valve 15 becomes equal to or lower than the specified temperature, the main injector 5, the reforming injector 16, the main throttle valve 6 and the reforming throttle valve 15 are operated. Control to close. When the reforming injector 16 is closed, the supply of ammonia gas to the reformer 13 is stopped. When the reforming throttle valve 15 is closed, the supply of air to the reformer 13 is stopped.

FIG. 3 is a flowchart showing details of the control processing procedure executed by the control unit 30. This process is executed in the ammonia engine 2 during steady operation in which the ammonia gas burns together with the hydrogen in the reformed gas. During steady operation, the main injector 5, the main throttle valve 6, the reforming throttle valve 15, the reforming injector 16, and the stop valve 20 are in the open state.

In FIG. 3, the control unit 30 first acquires the detected value of the pressure sensor 27 (procedure S101). Subsequently, the control unit 30 determines whether or not the remaining amount of liquid ammonia in the ammonia tank 11 is equal to or less than a predetermined predetermined amount based on the detected value of the pressure sensor 27 (procedure S102).

When the remaining amount of liquid ammonia in the ammonia tank 11 becomes low, the residual pressure of the liquid ammonia in the ammonia tank 11 decreases. Therefore, the relationship between the remaining amount of liquid ammonia in the ammonia tank 11 and the residual pressure of liquid ammonia is obtained in advance by an experiment or the like and stored in a memory as map data.

Then, the control unit 30 determines whether or not the residual pressure of the liquid ammonia in the ammonia tank 11 is equal to or less than a predetermined predetermined pressure, and determines that the residual pressure of the liquid ammonia in the ammonia tank 11 is equal to or less than the predetermined pressure. When it is determined, it is determined that the remaining amount of liquid ammonia in the ammonia tank 11 is equal to or less than the specified amount. When the control unit 30 determines that the remaining amount of liquid ammonia in the ammonia tank 11 is not equal to or less than the specified amount, the control unit 30 executes the procedure S101 again.

When the control unit 30 determines that the remaining amount of liquid ammonia in the ammonia tank 11 is equal to or less than the specified amount, the display 29 indicates that the remaining amount of liquid ammonia in the ammonia tank 11 is almost empty. The display 29 is controlled so as to display (procedure S103). At this time, the display 29 may display a guide such as "automatic cool-down-> stop" in addition to the screen display that immediately indicates that the remaining amount of liquid ammonia is almost empty.

Then, the control unit 30 controls the reforming throttle valve 15 so that the opening degree of the reforming throttle valve 15 becomes small (procedure S104). As a result, the flow rate of the air supplied to the reformer 13 is reduced. At this time, the air supply flow rate is set so that the temperature of the reformer 13 _{is lower than the lower limit temperature TL} (see FIG. 4) in the oxidative deterioration temperature range in which the oxidative deterioration of the reforming catalyst 13b occurs. Further, the air supply flow rate is set to be smaller than, for example, the supply flow rate of ammonia gas (see FIG. 4).

Subsequently, the control unit 30 acquires the detected value of the temperature sensor 28 (procedure S105). Then, the control unit 30 determines whether or not the temperature of the reformer 13 is equal to or lower than a predetermined predetermined temperature based on the detected value of the temperature sensor 28 (procedure S106). The specified temperature is, for example, a temperature lower than the oxidative deterioration temperature range. When the control unit 30 determines that the temperature of the reformer 13 is not equal to or lower than the specified temperature, the control unit 30 executes the procedure S105 again.

When the control unit 30 determines that the temperature of the reformer 13 is equal to or lower than the specified temperature, the control unit 30 controls to close the main injector 5 and the reforming injector 16 (procedure S107). As a result, the supply of ammonia gas to the ammonia engine 2 and the reformer 13 is stopped.

Subsequently, the control unit 30 controls to close the reforming throttle valve 15 and the stop valve 20 (procedure S108). As a result, the supply of air to the reformer 13 is stopped. Subsequently, the control unit 30 controls to close the main throttle valve 6 (procedure S109). As a result, the supply of air to the ammonia engine 2 is stopped. Steps S108 and S109 are executed immediately after, for example, step S107. In addition, steps S107 to S109 may be executed at the same time.

Here, the remaining amount determination unit 31 executes the procedures S101 and S102. The display control unit 32 executes the procedure S103. The valve control unit 33 executes steps S104 to S109.

In the above, when the engine system 1 is started, the heating element 24 of the electric heater 17 generates heat. Then, when the reforming injector 16 opens, ammonia gas is injected from the reforming injector 16 and the ammonia gas is supplied to the reformer 13. At this time, the ammonia gas is heated by the heat of the heating element 24, and the heat of the warmed ammonia gas is transferred to the reformer 13, so that the temperature of the reformer 13 rises. Then, when the reforming throttle valve 15 is opened, air is supplied to the reformer 13. At this time, the supply flow rate of ammonia gas is larger than the supply flow rate of air (see FIG. 4).

Next, when the main throttle valve 6 and the main injector 5 are opened, air is supplied to the combustion chamber 2a of the ammonia engine 2, and ammonia gas is injected from the main injector 5 to the combustion chamber 2a of the ammonia engine 2. Ammonia gas is supplied.

When the temperature of the reformer 13 reaches the combustible temperature, the ammonia gas is burned by the reforming catalyst 13b of the reformer 13, and the temperature of the reformer 13 is further raised by the combustion heat. Specifically, as shown in the following formula, a combustion reaction of ammonia occurs due to a chemical reaction (oxidation reaction) between a part of ammonia and oxygen in the air.
NH ₃ + 3/4O ₂ → 1 / 2N ₂ + 3 / 2H ₂ O + Q

Then, when the temperature of the reformer 13 reaches the reformable temperature, the reforming catalyst 13b of the reformer 13 starts reforming the ammonia gas, and a reforming gas containing hydrogen is generated. Specifically, as shown in the following formula, a reforming reaction occurs in which ammonia is decomposed into hydrogen and nitrogen by the heat of combustion of ammonia, and a reforming gas containing hydrogen and nitrogen is generated.
NH ₃ → 3 / 2H ₂ + 1 / 2N ₂ −Q

The reformed gas flows through the reformed gas flow path 18 and is supplied to the combustion chamber 2a of the ammonia engine 2. As a result, the ammonia gas burns together with the hydrogen in the reformed gas in the combustion chamber 2a. As described above, the engine system 1 is in steady operation after the warming up of the reformer 13 is completed.

During such steady operation, ammonia gas is consumed, so that the remaining amount of liquid ammonia in the ammonia tank 11 gradually decreases. Then, when the remaining amount of liquid ammonia in the ammonia tank 11 is close to empty, the display 29 displays that the remaining amount of liquid ammonia in the ammonia tank 11 is close to empty. Then, the driver of the vehicle 10 sees the screen display of the display 29 and knows that the remaining amount of liquid ammonia in the ammonia tank 11 is almost empty, and manually drives the vehicle 10 to a safe place. Can be moved.

Further, when the remaining amount of liquid ammonia in the ammonia tank 11 is close to empty, the flow rate of the air supplied to the reformer 13 decreases. Therefore, as will be described later, the temperature rise of the reforming catalyst 13b of the reformer 13 is suppressed. However, since air continues to be supplied to the reformer 13, the reforming operation by the reformer 13 is continued.

After that, when the temperature of the reformer 13 becomes equal to or lower than the specified temperature, the main injector 5 and the reforming injector 16 are closed, so that the supply of ammonia gas to the ammonia engine 2 and the reformer 13 is stopped and the main When the throttle valve 6 and the reforming throttle valve 15 are closed, the supply of air to the ammonia engine 2 and the reformer 13 is stopped. As a result, the ammonia engine 2 coasts several times and then completely stops.

Here, in the normal state where the remaining amount of liquid ammonia in the ammonia tank 11 is sufficient, the flow rates of the ammonia gas and air supplied to the reformer 13 are constant as shown in FIG. 4A. Is. In FIG. 4, the solid line P indicates the flow rate of ammonia gas supplied to the reformer 13, and the broken line Q indicates the flow rate of air supplied to the reformer 13. At this time, the combustion reaction of ammonia, which is an exothermic reaction, and the reforming reaction of ammonia, which is an endothermic reaction, are in an equilibrium state. Therefore, the temperature of the reforming catalyst 13b (see the solid line R in FIG. 4) becomes constant at a temperature lower than _{the lower limit temperature TL (described above) in the oxidative deterioration temperature range.}

When the remaining amount of liquid ammonia in the ammonia tank 11 becomes almost empty, the flow rate of the ammonia gas supplied to the reformer 13 decreases as shown in FIG. 4 (b). Therefore, since the reforming reaction of ammonia is suppressed, the thermal balance between the exothermic reaction and the endothermic reaction is lost, and the exothermic reaction is promoted as compared with the endothermic reaction. As a result, the temperature of the reforming catalyst 13b rises.

At this time, if the flow rate of the ammonia gas supplied to the reformer 13 is smaller than the flow rate of the air supplied to the reformer 13, the inside of the reformer 13 is easily exposed to the oxygen atmosphere. Therefore, when the temperature of the reforming catalyst 13b reaches the oxidative deterioration temperature range, the oxidative deterioration of the reforming catalyst 13b progresses.

In response to such a problem, as shown in FIG. 4C, the flow rate of air supplied to the reformer 13 when the remaining amount of liquid ammonia in the ammonia tank 11 is almost empty. When the amount is reduced, the inside of the reformer 13 is less likely to be exposed to the oxygen atmosphere. Further, by reducing the flow rate of the air supplied to the reformer 13, the promotion of the combustion reaction of the reforming catalyst 13b can be suppressed. Therefore, the thermal balance between the exothermic reaction and the endothermic reaction becomes uniform, and the temperature rise of the reforming catalyst 13b is suppressed, so that the temperature of the reforming catalyst 13b is prevented from reaching the oxidative deterioration temperature range. Therefore, even if the inside of the reformer 13 is slightly exposed to an oxygen atmosphere, the progress of oxidative deterioration of the reforming catalyst 13b is suppressed.

As described above, in the present embodiment, when the reformer 13 and the ammonia engine 2 are supplied with ammonia gas and air, respectively, the reformer 13 reforms the ammonia gas to contain hydrogen. Gas is generated and the reformed gas is supplied to the ammonia engine 2. Then, in the ammonia engine 2, the ammonia gas burns together with the hydrogen in the reformed gas. Since ammonia gas is consumed during the combustion operation of the ammonia engine 2, the remaining amount of liquid ammonia in the ammonia tank 11 gradually decreases. Therefore, the pressure sensor 27 and the remaining amount determination unit 31 detect the remaining amount of liquid ammonia in the ammonia tank 11. At this time, when the remaining amount of liquid ammonia in the ammonia tank 11 is equal to or less than the specified amount, the reforming throttle valve 15 is controlled so that the flow rate of the air supplied to the reformer 13 decreases. Therefore, the inside of the reformer 13 is less likely to be exposed to the oxidizing atmosphere. Further, by reducing the flow rate of the air supplied to the reformer 13, the promotion of combustion of ammonia gas in the reformer 13 is suppressed, so that the temperature rise of the reformer 13 is suppressed. As described above, it is prevented that the reforming catalyst 13b of the reformer 13 is oxidatively deteriorated due to running out of fuel.

Further, even if it is detected that the remaining amount of liquid ammonia in the ammonia tank 11 is less than or equal to the specified amount, the reformer throttle valve 15 and the reformer are reformed so that the reformer 13 continues to generate the reformed gas for a specified time. The injector 16 is controlled. Therefore, since the supply of the reformed gas to the ammonia engine 2 is continued, the combustion operation of the ammonia engine 2 is continued. Therefore, it is possible to move the vehicle 10 to a safe place before the ammonia engine 2 is stopped. As a result, the ammonia engine 2 can be stopped in a safe place even in a situation where the fuel is likely to run out.

Further, in the present embodiment, the remaining amount of liquid ammonia in the ammonia tank 11 is detected from the residual pressure of the liquid ammonia in the ammonia tank 11 detected by the pressure sensor 27. By using the pressure sensor 27 in this way, the remaining amount of liquid ammonia in the ammonia tank 11 can be detected easily and inexpensively.

Further, in the present embodiment, when the temperature of the reformer 13 becomes equal to or lower than the specified temperature, the supply of ammonia gas and air to the reformer 13 is stopped, so that the reformer 13 stops the generation of the reformed gas. .. Further, since the supply of ammonia gas, air, and reforming gas to the ammonia engine 2 is also stopped, the ammonia engine 2 is stopped.

Further, in the present embodiment, when the remaining amount of liquid ammonia in the ammonia tank 11 is equal to or less than the specified amount, it is notified that the remaining amount of liquid ammonia is almost empty. Therefore, the driver of the vehicle 10 knows from the display 29 that the remaining amount of liquid ammonia in the ammonia tank 11 is small, and can reliably move the vehicle 10 to a safe place by manual driving.

FIG. 5 is a schematic configuration diagram showing a modified example of the engine system 1 shown in FIG. In FIG. 5, the engine system 1 of the present modification includes a flow meter 35 in addition to the configuration in the above embodiment. The flow meter 35 measures the flow rate of ammonia gas flowing through the ammonia gas flow path 21. The flow meter 35 constitutes a part of the remaining amount detecting unit that detects the remaining amount of liquid ammonia in the ammonia tank 11.

By using such a flow meter 35, the remaining amount of liquid ammonia in the ammonia tank 11 can be detected with high accuracy. It is also possible to detect an abnormality in the ammonia gas supply system such as the ammonia gas flow path 21, the vaporizer 12, and the pressure reducing valve 23.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the temperature of the reformer 13 is directly detected by the temperature sensor 28, but the present invention is not particularly limited to that, and the temperature of the reforming gas output from the outlet of the reformer 13 is measured by the temperature sensor. The temperature of the reformer 13 may be detected by measuring with 28 and estimating the temperature of the reformer 13 from the measured value.

Further, in the above embodiment, the main injector 5, the reforming injector 16, the main throttle valve 6, and the reforming throttle valve 15 are arranged so that the ammonia engine 2 is stopped when the temperature of the reformer 13 becomes equal to or lower than the specified temperature. And the stop valve 20 is closed-controlled, but is not particularly limited to such a form. For example, since it is possible to estimate the temperature of the reformer 13 from the flow rate of ammonia gas, the flow rate of air, the time, the room temperature, etc., the opening degree of the reformer throttle valve 15 is changed to be smaller. Based on the elapsed time, the main injector 5, the reforming injector 16, the main throttle valve 6, the reforming throttle valve 15, and the stop valve 20 may be closed-controlled so that the ammonia engine 2 is stopped.

Further, in the above embodiment, the reformer 13 has a reforming catalyst 13b having a function of burning ammonia gas and a function of decomposing ammonia gas into hydrogen. Not limited. The reformer 13 may have a combustion catalyst that burns ammonia gas and a reforming catalyst that decomposes ammonia gas into hydrogen.

Further, in the above embodiment, a plurality of main injectors 5 for injecting ammonia gas into each combustion chamber 2a of the ammonia engine 2 are attached to the ammonia engine 2, but the number of main injectors 5 is one. May be good. In this case, the main injector 5 may be arranged so as to inject ammonia gas into the intake passage 3.

Further, in the above embodiment, the air flow path 14 through which the air supplied to the reformer 13 flows is branched and connected to the intake passage 3, but the present invention is not particularly limited to that form, and the intake air connected to the ammonia engine 2 is connected. Air may be supplied to the air flow path 14 from a path different from the passage 3. In this case, it is possible to prevent the influence of the pulsation of the intake passage 3.

Further, in the above embodiment, the reforming injector 16 for injecting ammonia gas toward the reformer 13 is connected to the ammonia gas flow path 21, but the embodiment is not particularly limited, and for example, the reforming injector 16 Alternatively, a flow rate regulating valve may be used. In this case, the ammonia gas flow path 21 is connected to the air flow path 14, and a flow rate adjusting valve is provided in the ammonia gas flow path 21. By using the flow rate adjusting valve, ammonia gas can be continuously supplied to the reformer 13. In this case, the flow control valve constitutes an ammonia supply unit.

Further, in the above embodiment, the main throttle valve 6 is arranged in the intake passage 3 and the modified throttle valve 15 is arranged in the air flow path 14, but the throttle valve is not particularly limited to such a throttle valve, for example. A mass flow controller may be used. In this case, the mass flow controller arranged in the air flow path 14 constitutes an air flow rate adjusting unit. Further, the air flow rate adjusting unit may be a compressor, a pump, or the like.

Further, in the above embodiment, gaseous ammonia gas is used as the fuel supplied to the ammonia engine 2 and the reformer 13, but the present invention is not particularly limited, and liquid ammonia may be used. In this case, the vaporizer 12 becomes unnecessary.

Further, although the engine system 1 of the above embodiment is mounted on the engine type vehicle 10, the present invention can be applied to, for example, a high lid type vehicle. Further, the present invention is not particularly limited to vehicles, and can be applied to, for example, stationary generators and the like.

1 ... engine system, 2 ... ammonia engine (engine), 3 ... intake passage, 4 ... exhaust passage, 5 ... main injector (ammonia injection valve), 6 ... main throttle valve (air flow control valve), 13 ... reformer , 13b ... reforming catalyst (catalyst), 14 ... air flow path, 15 ... reforming throttle valve (air flow rate adjusting section), 16 ... reforming injector (ammonia supply section), 18 ... reforming gas flow path, 27 ... Pressure sensor (remaining amount detection unit), 28 ... Temperature sensor (temperature detection unit), 29 ... Display (notification unit), 31 ... Remaining amount determination unit (remaining amount detection unit), 32 ... Display control unit (notification unit) , 33 ... Valve control unit (control unit), 35 ... Flow meter (remaining amount detection unit).

Claims (4)

With the engine
The intake passage through which the air supplied to the engine flows and
The exhaust passage through which the exhaust gas generated from the engine flows, and
An ammonia injection valve that injects ammonia toward the engine,
An air flow rate control valve arranged in the intake passage and controlling the flow rate of the air supplied to the engine.
An ammonia tank for storing the ammonia and
A reformer having a catalyst that decomposes the ammonia into hydrogen by utilizing the heat generated by burning the ammonia, and reforming the ammonia to generate a reformed gas containing the hydrogen.
An air flow path through which the air supplied to the reformer flows, and
An ammonia supply unit that supplies the ammonia to the reformer,
An air flow rate adjusting unit arranged in the air flow path and adjusting the flow rate of the air supplied to the reformer.
A reformed gas flow path through which the reformed gas generated by the reformer flows toward the engine, and
A remaining amount detection unit that detects the remaining amount of the ammonia in the ammonia tank,
The ammonia injection valve, the air flow rate control valve, the ammonia supply unit, and the control unit for controlling the air flow rate adjusting unit are provided.
The control unit measures the flow rate of the air supplied to the reformer when the remaining amount of ammonia in the ammonia tank detected by the remaining amount detecting unit is equal to or less than a predetermined amount. An engine system that controls the air flow rate adjusting unit so as to reduce the amount. The engine system according to claim 1, wherein the remaining amount detecting unit has a pressure sensor that detects the residual pressure of the ammonia in the ammonia tank, and detects the remaining amount of ammonia from the residual pressure of the ammonia. A temperature detector for detecting the temperature of the reformer is further provided.
The control unit controls the air flow rate adjusting unit so as to reduce the flow rate of the air supplied to the reformer, and then the temperature of the reformer detected by the temperature detecting unit is predetermined. When the temperature falls below the specified temperature, the ammonia injection valve and the air flow rate control valve are controlled to be closed, and the ammonia supply unit and the air are stopped so as to stop the supply of the ammonia and the air to the reformer. The engine system according to claim 1 or 2, which controls a flow rate adjusting unit. Further provided is a notification unit for notifying that the remaining amount of ammonia in the ammonia tank detected by the remaining amount detecting unit is equal to or less than the specified amount. The engine system according to any one of claims 1 to 3.

Images