JP2020183337A - Hydrogen generator, internal combustion engine, method for controlling hydrogen generator, and computer program - Google Patents

Abstract

To provide a technique capable of generating hydrogen right after activating a hydrogen generator, in the hydrogen generator for generating the hydrogen from ammonia.SOLUTION: A hydrogen generator includes: a reformer in which a catalyst for reforming ammonia into hydrogen is stored; a supply part for supplying ammonia and air to the reformer; and a controller for controlling a quantity of air to be supplied to the reformer by the supply part, wherein the controller supplies the air of a smaller quantity than a target air quantity to the reformer when the supply part starts supplying the ammonia and air to the reformer, and thereafter the controller increases the quantity of air to be supplied to the reformer so that the air quantity becomes the target air quantity.SELECTED DRAWING: Figure 4

Description

The present invention relates to a hydrogen generator, an internal combustion engine, a control method for the hydrogen generator, and a computer program.

Conventionally, a hydrogen generating apparatus that generates hydrogen by reforming ammonia has been known (for example, Patent Document 1). When hydrogen is generated from ammonia in a hydrogen generator, it is necessary to bring the catalyst to a temperature suitable for the reforming reaction, so it is known that the temperature of the catalyst is raised by using the heat of oxidation generated by the oxidation reaction of ammonia. Has been done.

Japanese Unexamined Patent Publication No. 2013-234079

However, when hydrogen production is started while the temperature of the catalyst is lower than the temperature suitable for the reforming reaction, the catalyst may be cooled by the mixed gas of ammonia and air supplied to the catalyst. Therefore, it takes time to raise the temperature of the catalyst, and hydrogen may not be generated immediately after the hydrogen generator is started. In addition, since the oxidation reaction of ammonia in the catalyst is a transient reaction, if the residence time of the mixed gas in the catalyst is short, the mixed gas will pass through the catalyst as it is and be discharged without causing an oxidation reaction on the catalyst. In some cases. Therefore, since the amount of heat generated by the oxidation reaction of ammonia is reduced, it takes time to raise the temperature of the catalyst, and hydrogen may not be generated immediately after the hydrogen generator is started.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a technique capable of generating hydrogen immediately after starting a hydrogen generating device in a hydrogen generating device that generates hydrogen from ammonia. ..

The present invention has been made to solve at least a part of the above-mentioned problems, and can be realized as the following forms.

(1) According to one embodiment of the present invention, a hydrogen generating apparatus is provided. This hydrogen generator includes a reformer that houses a catalyst that reforms ammonia into hydrogen, a supply unit that supplies ammonia and air to the reformer, and air that is supplied to the reformer by the supply unit. A control unit for controlling the amount is provided, and the control unit supplies an air amount smaller than the target air amount to the reformer at the start of supplying ammonia and air to the reformer, and then supplies the reformer with the target. The amount of air supplied to the reformer is increased so as to have the amount of air.

According to this configuration, the control unit supplies the reformer with an amount of air less than the target amount of air at the start of supplying ammonia and air to the reformer, and then reforms the reformer so as to reach the target amount of air. Increase the amount of air supplied to the vessel. As a result, when the start of the hydrogen generator is started, the flow rate of air passing through the catalyst is reduced, so that the temperature drop of the catalyst due to air is suppressed, and the residence time of ammonia and air in the catalyst is increased, so that ammonia and air are separated. It is possible to suppress passing through the catalyst. Therefore, the oxidation reaction of ammonia is carried out immediately after the start of the hydrogen generating apparatus, and the temperature of the catalyst can be raised by the reaction heat generated in the oxidation reaction, so that hydrogen can be generated.

(2) In the hydrogen generator of the above embodiment, even if the control unit supplies the reformer with an amount of air that is less than half of the target amount of air at the start of supplying ammonia and air to the reformer. Good. According to this configuration, the control unit supplies the reformer with an amount of air that is less than half of the target amount of air at the start of supplying ammonia and air to the reformer. As a result, the flow rate of air passing through the catalyst is further reduced, so that the temperature drop of the catalyst due to air can be further suppressed, and the passage of ammonia and air through the catalyst can be further suppressed. Therefore, hydrogen can be generated immediately after the hydrogen generator is started.

(3) In the hydrogen generator of the above embodiment, the control unit increases the amount of air supplied to the reformer with the passage of time after the supply of ammonia and air to the reformer is started. It may be increased. According to this configuration, the amount of air supplied to the reformer gradually increases with the passage of time, so that it is possible to suppress a decrease in the temperature of the catalyst due to a sudden change in the flow rate of ammonia and air. it can. As a result, hydrogen can be continuously generated immediately after the hydrogen generation device is started.

(4) The hydrogen generation device of the above embodiment further includes a detection unit for detecting the temperature of the catalyst, and the control unit is attached to the reformer according to the temperature of the catalyst detected by the detection unit. The rate of increase in the amount of air supplied may be changed. According to this configuration, the control unit changes the rate of increase in the amount of air according to the temperature of the catalyst detected by the detection unit. For example, when the temperature of the catalyst tends to rise, the control unit increases the rate of increase in the amount of air. If the temperature of the catalyst does not rise easily, the rate of increase in the amount of air is reduced. In this way, since the amount of air supplied to the catalyst can be adjusted according to the temperature of the catalyst, the temperature of the catalyst can be quickly set to a temperature suitable for hydrogen production, and hydrogen can be continuously produced. Can be supplied.

(5) According to another embodiment of the present invention, there is provided an internal combustion engine that obtains a driving force by burning ammonia. This internal combustion engine includes an engine main body including a combustion chamber, an ammonia supply unit that supplies ammonia to the combustion chamber, and a hydrogen generation device of the above-described embodiment that supplies hydrogen to the combustion chamber. According to this configuration, the hydrogen generator can generate hydrogen immediately after the start of the internal combustion engine, so that hydrogen can be supplied to the internal combustion engine immediately after the start. As a result, misfire in the internal combustion engine immediately after starting can be suppressed.

(6) According to still another embodiment of the present invention, a method for controlling a hydrogen generator is provided. The control method of this hydrogen generator is to supply an amount of air less than the target amount of air to the reformer at the start of supplying ammonia and air to the reformer containing a catalyst for reforming ammonia into hydrogen. A first step and after the first step, a second step of increasing the amount of air supplied to the reformer so as to reach the target amount of air is provided. According to this configuration, in the first step, when the supply of ammonia and air to the reformer is started, an air amount smaller than the target air amount is supplied to the reformer. Then, in the second step, the amount of air supplied to the reformer is increased so as to reach the target amount of air. As a result, the oxidation reaction of ammonia is carried out immediately after the start of the hydrogen generating apparatus, and the heat of reaction generated by the oxidation reaction can raise the temperature of the catalyst, so that hydrogen can be generated.

The present invention can be realized in various aspects, for example, a system including a hydrogen generation device, a control method of these devices and systems, a computer program for executing a hydrogen generation method in these devices and systems, and the like. It can be realized in the form of a server device for distributing a computer program, a non-temporary storage medium for storing the computer program, or the like.

It is a figure which shows the schematic structure of the engine system of 1st Embodiment. It is a figure which shows the schematic structure of the reformer of 1st Embodiment. It is explanatory drawing explaining the equilibrium of the reforming reaction in a catalyst. It is a figure which shows the time change of the flow rate control value in the hydrogen generation part of 1st Embodiment. It is a figure which shows the time change of the torque of the engine system of 1st Embodiment. It is explanatory drawing explaining the flow rate control value in the hydrogen generation part of the comparative example. It is a figure which shows the schematic structure of the engine system of 2nd Embodiment. It is a figure which shows the time change of the air amount in the hydrogen generation part of the 2nd Embodiment. It is a figure which shows the time change of the air amount under the condition different from FIG. It is a figure which shows the time change of the air amount under the condition different from FIGS. 8 and 9. It is a figure which shows the time change of the air amount in the hydrogen generation part of the comparative example.

<First Embodiment>
FIG. 1 is a diagram showing a schematic configuration of the engine system 1 of the first embodiment. FIG. 2 is a diagram showing a schematic configuration of a reformer 35 of a hydrogen generating unit 30 included in the engine system 1 of the present embodiment. The engine system 1 includes an ammonia engine 11, an intake pipe 21, an air throttle 23, an ammonia injection valve 25, a hydrogen generation unit 30, an exhaust pipe 41, and a control unit 50. Ammonia gas (hereinafter, simply "" It burns (called "ammonia") to generate driving force.

The ammonia engine 11 is a spark ignition type and has a cylinder block 12 and a cylinder head 13. A piston 14 is arranged inside the cylinder block 12, and a combustion chamber 15 of the ammonia engine 11 is formed by the crown surface of the piston 14, the cylinder block 12, and the cylinder head 13. In the present embodiment, only one combustion chamber 15 is shown in the engine system 1, but the engine system 1 may have a plurality of combustion chambers 15.

An intake pipe 21 forming an intake path to the combustion chamber 15 and an exhaust pipe 41 forming an exhaust path from the combustion chamber 15 are connected to the combustion chamber 15 via the inside of the cylinder block 12. The cylinder block 12 is provided with a spark plug 16, an intake valve 17, and an exhaust valve 18. The spark plug 16 ignites the fuel in the combustion chamber 15 and burns the fuel by generating a spark discharge in the combustion chamber 15. The spark plug 16 may be a plasma jet spark plug. The intake valve 17 opens and closes the intake path to the combustion chamber 15. The exhaust valve 18 opens and closes the exhaust path from the combustion chamber 15.

The intake pipe 21 is connected to the cylinder block 12 and is formed so that the atmosphere and the combustion chamber 15 can communicate with each other. The intake pipe 21 is provided with an air throttle 23 and an ammonia injection valve 25. The air throttle 23 controls the amount of air flowing through the intake pipe 21 in response to a command from the electrically connected control unit 50. The ammonia injection valve 25 is provided on the cylinder head 13 side of the air throttle 23 in the intake pipe 21, and is electrically connected to the control unit 50. The ammonia injection valve 25 controls the amount of ammonia injected into the intake pipe 21 in response to a command from the control unit 50.

The hydrogen generation unit 30 includes an intake bypass pipe 31, a bypass air throttle 32, a bypass ammonia injection valve 33, an ammonia tank 34, and a reformer 35. The hydrogen generation unit 30 generates hydrogen from ammonia and supplies the generated hydrogen to the combustion chamber 15 via the intake pipe 21.

As shown in FIG. 1, the intake bypass pipe 31 is connected to the intake pipe 21 on the upstream side of the air throttle 23 and the intake pipe 21 between the air throttle 23 and the ammonia injection valve 25. The intake bypass pipe 31 is provided with a bypass air throttle 32, a bypass ammonia injection valve 33, and a reformer 35.

The bypass air throttle 32 is provided in the bypass ammonia injection valve 33 and the intake bypass pipe 31 on the upstream side of the reformer 35, and is electrically connected to the control unit 50. The bypass air throttle 32 controls the amount of air flowing from the intake pipe 21 into the intake bypass pipe 31 in response to a command from the control unit 50. The bypass ammonia injection valve 33 is provided in the intake bypass pipe 31 on the upstream side of the reformer 35, and is electrically connected to the control unit 50. The bypass ammonia injection valve 33 controls the amount of ammonia injected into the intake bypass pipe 31 in response to a command from the control unit 50.

The ammonia tank 34 is a container for storing ammonia, and is connected to the ammonia injection valve 25 and the bypass ammonia injection valve 33 via the ammonia pipe 34a as shown in FIG. The ammonia stored in the ammonia tank 34 is regulated by the pressure reducing valve 34b provided in the ammonia pipe 34a, and is supplied to the ammonia injection valve 25 and the bypass ammonia injection valve 33 in response to a command from the control unit 50. ..

As shown in FIG. 2, the reformer 35 includes a catalyst 35a, a gas heater 35b, a catalyst heater 35c, and a container 35d accommodating the catalyst 35a and the gas heater 35b. In the reformer 35, the ammonia flowing into the inside of the container 35d through the intake bypass pipe 31 is reformed into hydrogen by the catalyst 35a. The reformed hydrogen, together with unreacted ammonia and water produced by the reforming, is discharged from the reservoir 35d as a reformed gas. The reformed gas discharged from the reservoir 35d passes through the intake bypass pipe 31 on the downstream side of the reformer 35 and joins the gas flowing through the intake pipe 21.

The catalyst 35a produces hydrogen using a mixed gas of ammonia and air when the temperature is about 250 ° C. Specifically, hydrogen is generated by advancing the decomposition reaction of ammonia, which is an endothermic reaction, by utilizing the heat of oxidation generated by the oxidation of a part of ammonia. Therefore, in order to generate hydrogen using the catalyst 35a, it is necessary to set the temperature of the catalyst 35a to about 250 ° C., which is the active temperature of the catalyst 35a.

The gas heater 35b is arranged on the upstream side of the catalyst 35a inside the container 35d. The gas heater 35b is electrically connected to the control unit 50 and generates heat in response to a command from the control unit 50. The gas heater 35b heats a mixed gas of ammonia and air flowing into the inside of the container 35d. The catalyst 35a is heated by the mixed gas of heated ammonia and air flowing into the catalyst 35a. The catalyst heater 35c is arranged around the catalyst 35a outside the container 35d. The catalyst heater 35c is electrically connected to the control unit 50 and generates heat in response to a command from the control unit 50. The catalyst heater 35c heats the catalyst 35a from the surroundings. That is, the gas heater 35b and the catalyst heater 35c are used to heat the catalyst 35a. The catalyst 35a can be heated by using at least one of the gas heater 35b and the catalyst heater 35c. Further, when the reaction in the catalyst 35a proceeds sufficiently and the temperature of the catalyst 35a can be maintained above the active temperature only by the heat of reaction, heating by the gas heater 35b and the catalyst heater 35c becomes unnecessary.

The exhaust pipe 41 is connected to the cylinder block 12 and is formed so that the atmosphere and the combustion chamber 15 can communicate with each other. The exhaust pipe 41 discharges the gas generated by combustion in the combustion chamber 15 to the atmosphere.

The control unit 50 is a computer including a ROM, a RAM, and a CPU. The control unit 50 adjusts the amount of air flowing through the intake pipe 21 by controlling the air throttle 23, and adjusts the amount of air flowing through the intake bypass pipe 31 by controlling the bypass air throttle 32. Further, the control unit 50 adjusts the injection amount of ammonia to the intake pipe 21 by controlling the ammonia injection valve 25, and the injection amount of ammonia to the intake bypass pipe 31 by controlling the bypass ammonia injection valve 33. Or adjust. Further, the control unit 50 controls heating by the gas heater 35b and the catalyst heater 35c. The details of the control by the control unit 50 will be described later.

Next, the operation of the engine system 1 will be described. In the engine system 1 of the present embodiment, when starting, hydrogen is supplied to the combustion chamber 15 by the ammonia injection valve 25, and hydrogen generated in the reformer 35 is supplied to the combustion chamber 15 as an auxiliary fuel for ammonia. .. Specifically, when the cooling water temperature of the ammonia engine 11 is low, the amount of air supplied to the reformer 35 is increased by setting the air throttle 23 on the closed side and the bypass air throttle 32 on the open side. .. In addition, the amount of ammonia injected by the bypass ammonia injection valve 33 is also increased. As a result, the engine system 1 is started by the combustion of a relatively large amount of hydrogen and ammonia supplied to the combustion chamber 15. Further, when the ammonia engine 11 is relatively warm, the air throttle 23 is slightly closed to reduce the amount of air supplied to the reformer 35 and the amount of ammonia injected by the bypass ammonia injection valve 33. As a result, the engine system 1 is started by combustion of a relatively small amount of hydrogen and ammonia supplied to the combustion chamber 15. After the engine system 1 is started, the control unit 50 controls the injection amount of ammonia injected from the ammonia injection valve 25 according to the oxygen concentration of the exhaust pipe 41 detected by an oxygen concentration meter (not shown), and desires it. The engine system 1 is controlled so that the torque is output.

In the present embodiment, when the engine system 1 is started, the control unit 50 supplies the reformer 35 with an amount of air less than the target amount of air when the supply of ammonia and air to the reformer 35 is started. Here, the "target air amount" will be described.

FIG. 3 is an explanatory diagram illustrating the equilibrium of the reforming reaction in the catalyst that reforms ammonia to hydrogen. In FIG. 3, the horizontal axis shows the ratio of air to ammonia, and the vertical axis shows the composition ratio of the reformed gas at the outlet of the reformer. In FIG. 3, the composition ratio of H ₂ is indicated by the solid line L31, the composition ratio of NH ₃ is indicated by the broken line L32, the composition ratio of N ₂ is indicated by the one-dot chain line L33, and the composition ratio of H ₂ O is indicated by the two-dot chain line L34. Indicated by. In the reforming of ammonia to hydrogen by a catalyst, as shown in FIG. 3, the composition ratio of hydrogen in the reformed gas is slightly lower than the maximum value under the condition that the ratio of air to ammonia is 0.8. , The composition ratio of ammonia becomes almost 0%. Therefore, in the present embodiment, the amount of air when the ratio of air to ammonia in the mixed gas is 0.8 is set as the target amount of air.

FIG. 4 is a diagram showing a time change of the flow rate control value in the hydrogen generation unit 30 of the present embodiment. The vertical axis of FIG. 4 shows the flow rate control value in the command output from the control unit 50 to the bypass air throttle 32 and the bypass ammonia injection valve 33. In FIG. 4, the flow rate control value corresponding to the amount of air supplied to the reformer 35 is indicated by the broken line L41, and the flow rate control value corresponding to the amount of ammonia supplied to the reformer 35 is indicated by the alternate long and short dash line L42. The vertical axis of FIG. 4 shows the flow rate control value At0 corresponding to the above-mentioned target air amount.

In the engine system 1 of the present embodiment, when the supply of ammonia and air to the reformer 35 starts (time 0 seconds in FIG. 4), the flow rate control value corresponding to the amount of air supplied to the reformer 35 is set. The value At1 is less than half of the flow rate control value At0 corresponding to the target air amount. In the present embodiment, as shown in FIG. 4, the flow rate control value corresponding to the amount of air increases with the passage of time after the start of supply of ammonia and air to the reformer 35, and finally, The flow rate control value At0 corresponding to the target air amount is obtained.

FIG. 5 is a diagram showing a time change of the torque output by the engine system 1 of the present embodiment. The time shown on the horizontal axis of FIG. 5 indicates the same time as the time shown on the horizontal axis of FIG. As shown in FIG. 5, it can be seen that the engine system 1 outputs torque at the same time when the supply of ammonia and air to the reformer 35 starts (time 0 seconds in FIG. 5).

Generally, the catalyst used for the production of hydrogen oxidizes a mixed gas containing ammonia and air with a catalyst that carries out an oxidation reaction, and then uses the reaction heat to carry out a reforming reaction of ammonia. It is necessary to raise the temperature sufficiently to promote the reaction and keep it in an active state. However, if a large amount of a mixed gas of ammonia and air is supplied to the catalyst, the reforming reaction of ammonia in the catalyst may not proceed. Specifically, since the catalyst is cooled by a large amount of mixed gas, the temperature of the catalyst is lowered and it becomes difficult to reach a temperature suitable for the reforming reaction of ammonia. Therefore, since the catalyst remains in an inactive state, the period during which hydrogen is not generated without the oxidation reaction may be extended. Further, even if the temperature of the catalyst is suitable for the reforming reaction of ammonia, the oxidation reaction in the catalyst is a transient reaction. Therefore, if the residence time of the mixed gas is short, the reaction does not occur on the catalyst. It may slip through as it is and be discharged from the catalyst. Therefore, since the amount of heat generated by the oxidation reaction is reduced, the period during which hydrogen is not generated may be lengthened. As described above, if a large amount of a mixed gas of ammonia and air is supplied to the catalyst when the engine system is started, hydrogen cannot be supplied to the combustion chamber, so that the engine system may misfire.

FIG. 6 is an explanatory diagram for explaining the flow rate control value in the hydrogen generating section of the comparative example. FIG. 6A is a diagram showing a time change of the flow rate control value in the hydrogen generation unit of the comparative example, and FIG. 6B is a diagram showing the time change of the flow rate control value in the hydrogen generation part in FIG. 6 (b). It is a figure which shows the time change of the torque output by the engine system in the case of a). Here, in the hydrogen generating section of the comparative example, as shown in FIG. 6A, when the engine system was started, the same amount of ammonia (broken line L61 in FIG. 6A) and air (broken line L61 in FIG. 6A) were added to the reformer. The alternate long and short dash line L62) shown in FIG. 6A is supplied. As shown in FIG. 6A, when the same amount of ammonia and air are supplied to the reformer at the same time as the start of the engine system, the temperature of the catalyst drops or the mixed gas becomes the same as described above. Hydrogen cannot be produced in the catalyst because the residence time is shortened. Therefore, as shown in FIG. 6B, a certain period of time immediately after the start of the engine system starts is the misfire period (reference numeral P0 in FIG. 6B), and the engine system cannot output torque during the misfire period. It will be.

According to the hydrogen generation unit 30 of the present embodiment described above, the control unit 50 supplies the reformer 35 with an amount of air less than the target amount of air at the start of supplying ammonia and air to the reformer 35. After that, the amount of air supplied to the reformer 35 is increased so as to reach the target amount of air. As a result, when the start of the engine system 1 is started, the flow rate of air passing through the catalyst 35a is reduced, so that the temperature drop of the catalyst 35a due to air is suppressed, and the residence time of ammonia and air in the catalyst 35a is increased, so that the ammonia. And air can be prevented from passing through the catalyst 35a. Therefore, the oxidation reaction of ammonia is carried out immediately after the start of the hydrogen generation unit 30, and the temperature of the catalyst 35a can be raised by the reaction heat generated in the oxidation reaction, so that hydrogen can be generated.

Further, according to the hydrogen generation unit 30 of the present embodiment, the control unit 50 supplies the reformer 35 with an amount of air that is less than half of the target air amount at the start of supplying ammonia and air to the reformer 35. .. As a result, the flow rate of air passing through the catalyst 35a is further reduced, so that the temperature drop of the catalyst 35a due to air can be further suppressed, and the passage of ammonia and air through the catalyst 35a can be further suppressed. Therefore, hydrogen can be generated immediately after the hydrogen generation unit 30 is started.

Further, according to the hydrogen generation unit 30 of the present embodiment, the amount of air supplied to the reformer 35 gradually increases with the passage of time, so that the catalyst 35a is affected by a sudden change in the flow rate of ammonia and air. It is possible to suppress the decrease in temperature. As a result, hydrogen can be continuously generated immediately after the hydrogen generation unit 30 is started.

Further, according to the engine system 1 of the present embodiment, since the hydrogen generation unit 30 can generate hydrogen immediately after the engine system 1 is started, hydrogen can be supplied to the combustion chamber 15 immediately after the start. As a result, misfire in the engine system 1 immediately after starting can be suppressed.

Further, according to the control method of the hydrogen generation unit 30 of the present embodiment, first, as the first step, when the supply of ammonia and air to the reformer 35 is started, the amount of air less than the target amount of air is reformed. It is supplied to the vessel 35. Then, as a second step, the amount of air supplied to the reformer 35 is increased so as to reach the target amount of air. As a result, the oxidation reaction of ammonia is carried out immediately after the start of the hydrogen generation unit 30, and the heat of reaction generated by the oxidation reaction can raise the temperature of the catalyst 35a, so that hydrogen can be generated.

<Second Embodiment>
FIG. 7 is a diagram showing a schematic configuration of the engine system 2 of the second embodiment. The engine system 2 of the second embodiment is different from the engine system 1 of the first embodiment (FIG. 1) in that a thermocouple 66 is provided in the hydrogen generation unit 60.

The hydrogen generation unit 60 included in the engine system 2 includes an intake bypass pipe 31, a bypass air throttle 32, a bypass ammonia injection valve 33, an ammonia tank 34, a reformer 35, and a thermocouple 66. The thermocouple 66 is provided in the reformer 35 and detects the temperature of the catalyst 35a. The thermocouple 66 outputs the detected temperature of the catalyst 35a to the control unit 50.

A table corresponding to the rate of change in the temperature of the catalyst 35a and the rate of increase in the amount of air supplied to the reformer 35 is input to the control unit 50 of the second embodiment. The control unit 50 of the second embodiment uses the temperature of the table and the catalyst 35a detected by the thermocouple 66 to change the rate of increase in the amount of air supplied to the reformer 35.

FIG. 8 is a diagram showing the time change of the amount of air in the hydrogen generating unit 60 of the present embodiment. In FIG. 8, the horizontal axis shows the time, the first vertical axis shows the amount of air supplied to the reformer 35, and the second vertical axis shows the temperature of the catalyst 35a. FIG. 8 shows the target air amount At2 on the first vertical axis and the activity temperature Ta of the catalyst 35a on the second vertical axis. In FIG. 8, the amount of air supplied to the reformer 35 is indicated by the broken line L81, and the temperature of the catalyst 35a is indicated by the alternate long and short dash line L82.

As shown in FIG. 8, in the hydrogen generation unit 60, at the start of supplying ammonia and air to the reformer 35 (time t0 in FIG. 4), the air amount At3, which is less than half of the target air amount At2, and the ammonia Is supplied to the reformer 35. As a result, the temperature of the catalyst 35a drops once after the time t0, but the amount of air supplied is less than the target amount of air At2, so that the temperature of the catalyst 35a is lower than the active temperature at which the reforming reaction of ammonia to hydrogen is possible. Absent. As a result, hydrogen is supplied to the combustion chamber 15 immediately after the start of the engine system 2, and then hydrogen is continuously supplied to the combustion chamber 15, so that misfire in the engine system 2 is suppressed.

FIG. 9 is a diagram showing a time change of the amount of air under conditions different from those in FIG. FIG. 9 is a diagram showing the time change of the amount of air when the temperature rise of the catalyst 35a is faster than that of FIG. 8, and the amount of air supplied to the reformer 35 is indicated by the broken line L91, and the temperature of the catalyst 35a is shown. Is indicated by the alternate long and short dash line L92. In FIG. 9, for comparison, the amount of air supplied to the reformer 35 shown in FIG. 8 (broken line L81) and the temperature of the catalyst 35a (dashed line L82) are shown by thin lines.

As shown in FIG. 9, when the temperature of the catalyst 35a rises relatively quickly, the control unit 50 uses a table input in advance to set the rate of increase in the amount of air as the rate of increase in the amount of air in FIG. (Period P21 between time t0 and time t1 shown in FIG. 9). As a result, the amount of air reaches the target amount of air At2 relatively quickly, so that the target amount of hydrogen can be quickly supplied to the combustion chamber 15.

FIG. 10 is a diagram showing a time change of the amount of air under conditions different from those of FIGS. 8 and 9. FIG. 10 is a diagram showing a time change of the amount of air when the temperature rise of the catalyst 35a is slower than that of FIG. 8, and the amount of air supplied to the reformer 35 is indicated by a broken line L01, and the temperature of the catalyst 35a is shown. Is indicated by the alternate long and short dash line L02. In addition, in FIG. 10, for comparison, the amount of air supplied to the reformer 35 shown in FIG. 8 (broken line L81) and the temperature of the catalyst 35a (dashed line L82) are shown by thin lines.

As shown in FIG. 10, when the temperature rise of the catalyst 35a is relatively slow, the control unit 50 uses a table input in advance to set the rate of increase in the amount of air to the rate of increase in the amount of air in FIG. (Period P22 between time t0 and time t2 shown in FIG. 10). As a result, the amount of air reaches the target amount of air At2 without the temperature of the catalyst 35a falling below the active temperature. Therefore, after starting the supply of ammonia and air to the reformer 35, hydrogen is continuously supplied to the combustion chamber 15 Can be supplied to.

FIG. 11 is a diagram showing the time change of the amount of air in the hydrogen generating section in the comparative example. In the hydrogen generating section in the comparative example, the amount of air supplied to the reformer is set as the target air volume when the engine system including the hydrogen generating section of the comparative example is started (broken line La1 in FIG. 11), so that the mixed gas is used. The temperature of the catalyst to be cooled will be lower than the active temperature (broken line La2 in FIG. 11). Therefore, during the period when the temperature of the catalyst is equal to or lower than the active temperature (the period P23 between the time t0 and the time t3 shown in FIG. 11), the hydrogen generating unit of the comparative example cannot supply hydrogen to the combustion chamber. , The engine system of the comparative example may misfire immediately after starting.

According to the hydrogen generation unit 60 of the present embodiment described above, the control unit 50 changes the rate of increase in the amount of air according to the temperature of the catalyst 35a detected by the thermocouple 66. When the temperature of the catalyst 35a is likely to rise, the control unit 50 increases the rate of increase in the amount of air as shown in FIG. Further, when the temperature of the catalyst 35a is difficult to rise, the rate of increase in the amount of air is reduced as shown in FIG. In this way, since the amount of air supplied to the catalyst 35a can be adjusted according to the temperature of the catalyst 35a, the temperature of the catalyst 35a can be quickly set to a temperature suitable for hydrogen production, and hydrogen can be used. It can be continuously supplied to the combustion chamber 15.

<Modified example of this embodiment>
The present invention is not limited to the above-described embodiment, and can be implemented in various aspects without departing from the gist thereof. For example, the following modifications are also possible.

[Modification 1]
In the above-described embodiment, the hydrogen generating units 30 and 60 as the "hydrogen generating device" and the control unit 50 are provided in the engine systems 1 and 2 as the "internal combustion engine" using ammonia as fuel. However, the field to which the "hydrogen generator" is applied is not limited to this. It is applicable in the field where a single hydrogen gas is used.

[Modification 2]
In the above-described embodiment, the target air amount is the amount of air when the ratio of air to ammonia in the mixed gas is 0.8. However, the target air volume is not limited to this. For example, it may be the amount of air for generating the amount of hydrogen that can drive the engine system 1 immediately after starting.

[Modification 3]
In the above-described embodiment, it is assumed that less than half of the target air amount is supplied to the reformer 35 at the start of supplying ammonia and air to the reformer 35. However, the amount of air supplied to the reformer 35 is not limited to this, and the amount of air supplied to the reformer 35 at the start of supplying ammonia and air to the reformer 35 is less than the target amount of air. Good.

[Modification example 4]
In the above-described embodiment, the amount of air supplied to the reformer 35 is determined to increase with the passage of time after the start of supply of ammonia and air to the reformer 35. However, the method of increasing the amount of air is not limited to this. For example, even if the amount of air supplied at the start of supplying ammonia and air to the reformer 35 at a specific time after the start of supplying ammonia and air to the reformer 35 is suddenly increased to the target amount of air. Good.

[Modification 5]
In the second embodiment, the rate of change in the temperature of the catalyst 35a is used to change the rate of increase in the amount of air supplied to the reformer 35. However, the item for changing the rate of increase in the amount of air supplied to the reformer 35 is not limited to the temperature. For example, the oxygen concentration of the exhaust pipe 41 may be used to change the rate of increase in the amount of oxygen, or the torque of the ammonia engine 11 may be used to change the rate of increase in the amount of oxygen.

Although the present embodiment has been described above based on the embodiments and modifications, the embodiments of the above-described embodiments are for facilitating the understanding of the present embodiment, and do not limit the present embodiment. This aspect may be modified or improved without departing from its spirit and claims, and this aspect includes its equivalents. In addition, if the technical feature is not described as essential in the present specification, it may be deleted as appropriate.

1, 2 ... Engine system 11 ... Ammonia engine 12 ... Cylinder block 13 ... Cylinder head 14 ... Piston 15 ... Combustion chamber 16 ... Spark plug 17 ... Intake valve 18 ... Exhaust valve 21 ... Intake pipe 23 ... Air throttle 25 ... Ammonia injection valve 30, 60 ... Hydrogen generator 31 ... Intake bypass pipe 32 ... Bypass air throttle 33 ... Bypass ammonia injection valve 34 ... Ammonia tank 34a ... Ammonia pipe 34b ... Pressure reducing valve 35 ... Reformer 35a ... Catalyst 35b ... Gas heater 35c ... Catalyst heater 35d ... Container 41 ... Exhaust pipe 50 ... Control unit 66 ... Thermoelectric pair

Claims (7)

It ’s a hydrogen generator,
A reformer containing a catalyst that reforms ammonia into hydrogen,
A supply unit that supplies ammonia and air to the reformer,
A control unit that controls the amount of air supplied to the reformer by the supply unit is provided.
At the start of supplying ammonia and air to the reformer, the control unit supplies an air amount smaller than the target air amount to the reformer, and then the reformer so as to reach the target air amount. Increase the amount of air supplied to
Hydrogen generator. The hydrogen generating apparatus according to claim 1.
When the supply of ammonia and air to the reformer is started, the control unit supplies the reformer with an amount of air that is less than half of the target amount of air.
Hydrogen generator. The hydrogen generating apparatus according to claim 1 or 2.
After the supply of ammonia and air to the reformer is started, the control unit increases the amount of air supplied to the reformer over time.
Hydrogen generator. The hydrogen generating apparatus according to any one of claims 1 to 3 further comprises.
A detection unit for detecting the temperature of the catalyst is provided.
The control unit changes the rate of increase in the amount of air supplied to the reformer according to the temperature of the catalyst detected by the detection unit.
Hydrogen generator. An internal combustion engine that obtains driving force by burning ammonia.
The engine body including the combustion chamber and
An ammonia supply unit that supplies ammonia to the combustion chamber and
The hydrogen generating apparatus according to any one of claims 1 to 4, wherein hydrogen is supplied to the combustion chamber.
Internal combustion engine. It is a control method for hydrogen generators.
The first step of supplying an amount of air less than the target amount of air to the reformer at the start of supplying ammonia and air to the reformer containing the catalyst for reforming ammonia into hydrogen, and
After the first step, a second step of increasing the amount of air supplied to the reformer so as to reach the target amount of air is provided.
Control method of hydrogen generator. A computer program that controls a hydrogen generator
A function to supply an amount of air less than the target amount of air to the reformer at the start of supply of ammonia and air to the reformer containing a catalyst for reforming ammonia into hydrogen.
The computer is made to perform a function of increasing the amount of air supplied to the reformer so as to reach the target amount of air.
Computer program.

Images