JP2017082670A - Engine system, and engine system operating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide, in an engine exhaust gas passage 2, an engine system capable of: utilizing a waste-heat on a low temperature side, on which the waste-heat has not been sufficiently utilized on an engine system including burning means 3 for burning a combustible substance in an exhaust gas, and nitrogen oxide removing means 4 for removing a nitrogen oxide; attaining clean exhaust and supplying an electric power for some time even after an engine stop.SOLUTION: An engine system comprises: urea water hydrolysis means 8 for hydrolyzing urea water by using the heat generated from an engine 1; and an ammonia fuel solid oxide type fuel cell 5 for using produced ammonia as a fuel, and fuel cell off-gas is introduced to and treated in said combustion means 3.SELECTED DRAWING: Figure 2

Description

The present invention includes an engine operated by burning hydrocarbon fuel;
The present invention relates to an engine system provided with combustion means for burning combustible substances in the exhaust gas and nitrogen oxide removal means for removing nitrogen oxides in the order of description in an exhaust gas passage through which exhaust gas generated from the engine flows.

  As a conventional technique for disclosing such an engine system, a technique disclosed in Patent Document 1 or Patent Document 2 can be cited. The techniques disclosed in these are mainly directed to diesel engines, but as shown in Patent Document 2, they can be applied to gas engines in addition to diesel engines [Patent Document 2, Paragraph 0021]. ].

The technique disclosed in Patent Document 1 aims to suppress dust accumulation in the exhaust gas purification means. In patent document 1, although the expression exhaust gas is employ | adopted, it is an agreement with the exhaust gas in this application.
This document relates to an exhaust gas treatment apparatus for a diesel engine 1 provided with a denitration catalyst 5 (nitrogen oxide removal means referred to in the present application) for removing nitrogen oxide in exhaust gas in an exhaust gas passage 2, upstream of the denitration catalyst 5. The exhaust gas passage 2 on the side is provided with a combustor 4 (combustion means referred to in the present application) for heating the exhaust gas passing through the exhaust gas passage 2 and burning the dust in the exhaust gas. It is always operated when the engine 1 is operated. As a result, there are provided an exhaust gas processing apparatus and an exhaust gas processing method capable of effectively removing harmful substances and lowering the combustion temperature during DPF regeneration.
Further, this document shows that an economizer 6 is provided on the downstream side of the denitration catalyst 5 for energy recovery.

  On the other hand, the technology disclosed in Patent Document 2 also relates to an exhaust gas treatment device for purifying harmful substances contained in exhaust gas discharged from an engine. The exhaust gas treatment device 20 shown in FIG. A DOC (Diesel Oxidation Catalyst) unit 22 for purifying carbon monoxide (CO) and HC (unburned hydrocarbon) contained in the exhaust gas, and a DPF for removing particulate matter (PM) contained in the exhaust gas ( A diesel particulate filter (23) unit 23 and an SCR (Selective Catalytic Reduction) unit 26 for reducing NOx contained in the exhaust gas are provided [paragraph 0023].

Each part is described as follows [the same paragraph 0023].
The DOC unit 22 includes an oxidation catalyst for purifying carbon monoxide (CO) and HC (unburned hydrocarbon) in the exhaust gas, and a support mechanism that supports the oxidation catalyst inside the exhaust pipe 21.
The DPF unit 23 includes a particulate collection filter for removing particulate matter (PM) in the exhaust gas.
The SCR unit 26 includes an SCR catalyst that is a denitration catalyst for promoting the reaction between ammonia generated from urea water injected into the exhaust gas and nitrogen oxide (NOx), and the SCR catalyst inside the exhaust pipe 21. And a support mechanism for supporting. A urea water supply mechanism 25 for supplying urea water used for denitration is provided upstream of the SCR unit 26 in the exhaust gas flow direction. The urea water supply mechanism 25 includes a urea water tank 25b in which urea water is stored, and a urea water spray nozzle 25a that sprays urea water into the exhaust gas from the urea water tank 25b. 1 illustrates the configuration in which the urea water supply mechanism 25 is provided between the DPF unit 23 and the SCR unit 26, the arrangement of the urea water supply mechanism 25 is not limited to this.

Therefore, the DOC portion 22 disclosed in this patent corresponds to the combustion means referred to in the present application, and the SCR portion 26 corresponds to the nitrogen oxide removing means.
Further, regarding the use of heat generated in the engine, there is a description regarding the exhaust gas recirculation cooler 12.

On the other hand, as a technique that is currently attracting attention, there is a technique for obtaining battery power using ammonia as a direct fuel (Patent Documents 3 and 4). These techniques are notable for purposes such as CO ₂ reduction because ammonia does not contain carbon. Further, no carbon deposit is generated on the electrode.
As a fuel cell using ammonia directly as a fuel, there is a solid oxide fuel cell (hereinafter referred to as SOFC), and today, ammonia is decomposed into hydrogen mainly in a battery electrode (anode). Development is progressing in the direction of causing a battery reaction while avoiding a decrease in output (Patent Documents 5 and 6).

JP 2014-34887 A JP-A-2015-68175 JP 2011-204416 A JP 2011-204418 A JP 2013-2111117 A JP2013-211118A

  In the engine system provided with the combustion means and the nitrogen oxide removal means in the exhaust gas path exhausted from the engine as described above, although the exhaust gas can be treated, the temperature range of exhaust heat that can be recovered by a normal economizer is 350 ° C. It is about ~ 200 ° C. However, the recovery by the economizer leaves room for consideration in terms of the timing of utilization of heat (energy) and the utilization efficiency.

  On the other hand, regarding the SOFC, considering the steady power generation stage, start-up stage, and stop stage, the fuel cell off-gas may contain fuel (ammonia, hydrogen) that was not used for power generation, and the anode in a high temperature state. Nitrogen contained in the off gas and oxygen contained in the cathode off gas may cause a combustion reaction and become nitrogen oxide (NOx) and be contained in the exhaust gas.

  In general, since the engine is equipped with a generator, the power from the generator can be used while the engine is operating. However, when the engine stops operating, it is desired to use the power after the engine is stopped. There is room for consideration in this case.

  An object of the present invention is to provide an engine system that can utilize exhaust heat on a low temperature side that has not been sufficiently utilized in the past, can easily purify exhaust, and can supply power for a certain period of time after the engine is stopped. There is in getting.

To achieve the above object, according to the present invention,
An engine operated by burning hydrocarbon fuel;
The engine system comprising the combustion means for combusting combustibles in the exhaust gas and the nitrogen oxide removing means for removing nitrogen oxides in the order of description in the exhaust gas path through which the exhaust gas generated from the engine flows.
Urea water hydrolysis means for hydrolyzing urea water supplied from urea water storage means for storing urea water using heat generated from the engine and / or the combustion means;
An ammonia fuel solid oxide fuel cell using ammonia produced by the urea water hydrolysis means as a fuel,
An off-gas introduction path for guiding the fuel cell off-gas generated from the ammonia fuel solid oxide fuel cell to the combustion means;
The fuel cell off-gas is treated by the combustion means and the nitrogen oxide removal means.

  This engine system includes urea water storage means and urea water hydrolysis means. The urea water hydrolysis means uses heat from the engine or the combustion means or both as an energy source (heat source) for generating the hydrolysis. The heat required for hydrolysis of urea water is about 350 to 200 ° C., and the heat in this temperature range can be fully utilized. As a result, it is possible to obtain ammonia as a fuel for the solid oxide fuel cell provided in the engine system according to the present application with respect to utilization of engine exhaust heat.

  If ammonia is retained in the system in the form of urea water as in the present application, the storage stability and the volume required for storage are more stable and lower than when stored as a gas, which is extremely advantageous. .

According to the above configuration, ammonia is supplied to the solid oxide fuel cell as fuel. The solid oxide fuel cell may be one that supplies ammonia directly to the anode of the fuel cell, or one that decomposes ammonia and supplies hydrogen to the anode. In this regard, the inventors have studied that the former may cause a decrease in power generation performance in the configuration in which ammonia is directly supplied to the anode and the configuration in which hydrogen is supplied to the anode as the cell temperature decreases. The latter configuration is preferred.
As described above, in the engine system according to the present application, energy can be used with high efficiency as electric power by supplying ammonia to the solid oxide fuel cell as fuel.

When ammonia is supplied to a solid oxide fuel cell as a fuel as described above, ammonia or hydrogen, which is a decomposition product thereof, is used for power generation from the solid oxide fuel cell as an off-gas. In some cases, the temperature of the battery is high, and oxygen is contained in the exhaust gas. Therefore, nitrogen oxides, carbon dioxide derived from urea water, water, and the like may be discharged.
However, in this application, since the fuel cell off-gas is led to the combustion means and the nitrogen oxide removal means in this order, the problem of releasing these components out of the system is provided for exhaust gas treatment from the engine side. It is possible to proceed by effectively utilizing the relatively powerful oxide / nitrogen oxide treatment system.

  Furthermore, when the engine, the combustion means, and the nitrogen oxide removal means constituting the system are started up, the urea water hydrolysis means and the solid oxide fuel cell are started up and a predetermined amount of ammonia is secured. Even after the engine is stopped, the operation of the solid oxide fuel cell can be continued with the ammonia as the fuel.

In the above configuration, it is preferable that the nitrogen oxide removing unit is an ammonia reduction type nitrogen oxide removing unit that uses ammonia generated by the urea water hydrolysis unit as a reducing agent.
The technology for treating nitrogen oxides using ammonia as a reducing agent is an established and highly reliable technology. Ammonia obtained by the urea water hydrolysis means provided in the engine system of the present application is treated with nitrogen oxide treatment and power generation. It can contribute to the stabilization and efficiency of the system.

Now, regarding the utilization of heat generated from the engine and / or the combustion means, the first heat utilization means used for heating the ammonia fuel solid oxide fuel cell and the urea water hydrolysis means A second heat utilization means used for hydrolysis
Preferably, the first heat utilization means uses heat on the high temperature side, and the second heat utilization means uses heat on the low temperature side that has been lowered by heat utilization in the first heat utilization means.

Since engine and combustor exhaust heat is normally about 600 to 800 ° C., the first heat utilization means uses the high temperature side to maintain the temperature of the solid oxide fuel cell, and heat at 350 to 200 ° C. is the second heat. Effective utilization of engine exhaust heat can be achieved by utilizing urea water in the utilization means.
Here, by providing a means such as heat exchange separately between the first heat utilization means and the second heat utilization means, heat in the intermediate temperature range (for example, about 600 to 350 ° C.) is recovered as usual. And can.

  Now, a gas-liquid separation means for gas-liquid separation of the decomposition product obtained by the urea water hydrolysis means described above is provided, and the liquid-side separation separated by this gas-liquid separation means is used as the engine or the combustion means. It is also preferable to adopt a configuration in which the gas is gasified by heat generated from both of them and supplied to the ammonia fuel solid oxide fuel cell as fuel.

  Later, as described in detail in the second embodiment, when there is an application other than the use of ammonia gas as a fuel (for example, when relatively low temperature ammonia gas can be used as it is), a gas-liquid separation means is provided. The gas side separation separated by the separation means is used as it is, and only the liquid side is further gasified with heat generated from the engine and / or the combustion means, and sent to the ammonia fuel solid oxide side fuel cell. The amount and properties (particularly temperature) of ammonia used for both applications can be suitably controlled, and the amount of heating on the fuel side that needs to be high can be adjusted to an appropriate minimum.

  Furthermore, the ammonia fuel solid oxide fuel cell is provided with a thermal decomposition means for thermally decomposing ammonia as a fuel by heat generated from the engine and / or the combustion means, and is generated by the thermal decomposition means. Preferably, hydrogen is supplied to the anode of the solid oxide fuel cell.

  As described above, according to the study by the inventors, in an ammonia fuel solid oxide fuel cell, when ammonia as a fuel is directly led to the anode and ammonia decomposition is caused in the immediate vicinity, the cell temperature ( A decrease in generated power may occur with a decrease in cell temperature.

  That is, according to the study by the inventors, depending on the temperature of the SOFC, the case where ammonia is directly supplied to the anode of the SOFC and the case where a mixture of hydrogen and nitrogen obtained by decomposing ammonia is supplied. As a result, it was found that the amount of current that can be extracted varies greatly.

The result of this examination will be described in detail based on FIG.
FIG. 4 shows the current density [A / cm ² ] on the horizontal axis and the average cell voltage [V] on the vertical axis. The average cell voltage increases as the current density increases at different operating temperatures. It is the result of testing how it changes.

In the test, a general SOFC having the following configuration was used as the SOFC cell.
FIG. 1 schematically shows an SOFC cell 55. The SOFC cell 55 is configured by having an anode 52 on one side of a solid electrolyte (solid oxide electrolyte) 51 and a cathode 53 on the other side. The fuel gas is supplied to the surface of the anode 52 opposite to the solid electrolyte 51, and the oxidizing gas is supplied to the surface of the cathode 53 opposite to the solid electrolyte 51 to cause a power generation reaction. The shape of the SOFC cell was a flat plate type. Therefore, the solid electrolyte 51, the anode (fuel electrode) 52, and the cathode (air electrode) 53 are basically flat, and the cell support type is the fuel electrode support type.

  The material of the solid oxide electrolyte 51 was an oxygen ion conductive ceramic material based on so-called YSZ (yttria-stabilized zirconia), and its thickness was in the range of 5 to 100 μm.

  As is well known, a fuel electrode material generally used in SOFC, which is determined depending on the fuel (in this case, ammonia), is selected for the fuel electrode 52 that is an anode. And solid oxide electrolyte particles.

  The material of the fuel electrode electrode catalyst is nickel, and the solid electrolyte particles contained in the fuel electrode 52 are the materials constituting the solid oxide electrolyte 51 described above. The thickness of the fuel electrode 52 was about 200 to 2000 μm.

  As a material of the air electrode 53 which is a cathode, the air electrode material used for normal SOFC was used. As is well known, the air electrode is formed by an air electrode electrode catalyst and solid oxide electrolyte particles.

  As the air electrode electrode catalyst, an oxide having a manganese-based, ferrite-based, cobalt-based or nickel-based perovskite structure is used, and the solid oxide electrolyte particles contained in the air electrode 53 are used in the fuel electrode. The same material as the solid oxide electrolyte particles that could be used was used. The thickness of the air electrode 53 was about 20 to 200 μm.

FIG. 4 shows the voltages when the battery temperatures are different, and each line on the lower right is the result at each battery temperature when hydrogen H ₂ and nitrogen N ₂ are supplied to the anode 52, and is distributed for each line. Each symbol position indicated by the symbol is the result when ammonia NH ₃ is supplied directly to the anode 52. The relationship between the symbol and temperature is shown in the upper right of the figure.

  As can be seen from this result, in a temperature range of 600 ° C. to 800 ° C., which is a general SOFC operating temperature range, in a relatively high temperature range (for example, 750 ° C. and 800 ° C.), it depends on the type of fuel. There is not much decrease in voltage. On the other hand, it can be seen that there is a large difference between the case where the fuel is hydrogen + nitrogen and the case where ammonia is used in the relatively low temperature range (for example, 600 ° C. and 650 ° C.). Furthermore, it can be seen that a considerable difference appears in the amount of current that can be taken out at 600 ° C.

  Therefore, by separately providing the thermal decomposition means, the performance that should be originally exhibited by the solid oxide fuel cell can be satisfactorily exhibited also in the engine system according to the present application using ammonia as a fuel.

Now, the nitrogen oxide removing means is ammonia reducing nitrogen oxide removing means using ammonia produced by the urea water hydrolysis means as a reducing agent,
Gas-liquid separation means for gas-liquid separation of the decomposition product obtained by the urea water hydrolysis means,
The gas-side separation separated by the gas-liquid separation means is supplied as a reducing agent to the ammonia reduction nitrogen oxide removal means, and the liquid-side separation is generated from the engine and / or the combustion means. Gasified by heat and supplied to the ammonia fuel solid oxide fuel cell as fuel,
Regarding the gas-liquid separation by the gas-liquid separation means, the amount of the gas-side separation is the amount of reducing agent required by the ammonia reduction-type nitrogen oxide removal means, and the amount of the liquid-side separation is the ammonia fuel. It is preferable to provide gas-liquid separation adjusting means for adjusting to an amount corresponding to the amount of fuel required in the solid oxide fuel cell.

  As described above, by providing the gas-liquid separation means, it is possible to adjust the temperature and amount between ammonia used as battery fuel and ammonia used for other purposes. Here, by adopting a configuration that uses ammonia that is a gas side separation in the ammonia reduction type nitrogen oxide removing means, power generation by the engine, power generation by the fuel cell, and further, the generation of nitrogen oxides accompanying these operations Generation can be controlled appropriately.

  As the engine used in the engine system described so far, a gasoline engine using gasoline as fuel, a diesel engine using diesel oil or gasoline as fuel, and a gas engine using hydrocarbon gas such as natural gas as fuel can be used. .

  In particular, since the engine system according to the present application includes combustion means and nitrogen oxide removal means, it is effective for a system in which a diesel engine in which combustible particles are a problem is used.

The above is the configuration of the engine system of the present application. As described above,
An engine operated by burning hydrocarbon fuel;
An engine system comprising combustion means for combusting combustibles in the exhaust gas and nitrogen oxide removing means for removing nitrogen oxide in the exhaust gas in the order of description in an exhaust gas path through which exhaust gas generated from the engine flows. As a driving method,
Urea water hydrolysis means for hydrolyzing urea water supplied from urea water storage means for storing urea water using heat generated from the engine and / or the combustion means;
An ammonia fuel solid oxide fuel cell using ammonia produced by the urea water hydrolysis means as a fuel,
In the engine system according to the present application, which includes an off-gas introduction path that guides a fuel cell off-gas generated from the ammonia fuel solid oxide fuel cell to the combustion means provided in the engine exhaust path,
The urea water is hydrolyzed from the urea water storage means by the urea water hydrolysis means using heat generated from the engine and / or the combustion means, or both, and the ammonia produced by the urea water hydrolysis means It is also possible to take the method of operating the engine system in which the ammonia fuel solid oxide fuel cell supplies electric power after stopping the power generation by the engine motive power.

  For example, while obtaining ammonia gas during engine operation and keeping the ammonia fuel solid oxide fuel cell in its power generation state, power generation on the fuel cell side can be continued even after the engine is stopped. That is, the ammonia fuel solid oxide fuel cell included in the present system can sufficiently serve as an auxiliary power source.

On the other hand, an engine operated by burning hydrocarbon fuel,
An engine system comprising combustion means for combusting combustibles in the exhaust gas and nitrogen oxide removing means for removing nitrogen oxide in the exhaust gas in the order of description in an exhaust gas path through which exhaust gas generated from the engine flows. As a driving method,
Urea water hydrolysis means for hydrolyzing urea water supplied from urea water storage means for storing urea water using heat generated from the engine and / or the combustion means;
An ammonia fuel solid oxide fuel cell using ammonia produced by the urea water hydrolysis means as a fuel,
An off-gas introduction path for guiding a fuel cell off-gas generated from the ammonia fuel solid oxide fuel cell to the combustion means provided in the engine exhaust gas path;
The nitrogen oxide removing means is ammonia reducing nitrogen oxide removing means using ammonia produced by the urea water hydrolysis means as a reducing agent,
Gas-liquid separation means for gas-liquid separation of the decomposition product obtained by the urea water hydrolysis means,
The gas-side separation separated by the gas-liquid separation means is supplied as a reducing agent to the ammonia reduction nitrogen oxide removal means, and the liquid-side separation is generated from the engine and / or the combustion means. As a configuration that gasifies by heat and supplies the fuel to the ammonia fuel solid oxide fuel cell, an engine system according to the present application is constructed,
Regarding the gas-liquid separation by the gas-liquid separation means, the amount of the gas-side separation is changed to the amount of reducing agent required by the ammonia reduction-type nitrogen oxide removal means, and the amount of the liquid-side separation is changed to the ammonia. By adjusting to an amount corresponding to the amount of fuel required in the fuel solid oxide fuel cell, the engine system can be appropriately operated with thermal and quantitative adjustment.

  Also in this method, the ammonia fuel solid oxide fuel cell is provided with a thermal decomposition means for thermally decomposing ammonia as a fuel by heat generated from the engine and / or the combustion means, or both, and the thermal decomposition means By adopting an operation mode in which hydrogen is generated and supplied to the anode of a solid oxide fuel cell, and ammonia that is a gas side separation is used in the ammonia reduction type nitrogen oxide removing means, It is possible to appropriately control power generation, power generation by the fuel cell, and generation of nitrogen oxides accompanying these operations.

The figure which shows the structure of the engine system 100 which concerns on 1st embodiment. The figure which shows the structure of the engine system 101 which concerns on 2nd embodiment. The figure which shows the specific structure of the solid oxide fuel cell which can be employ | adopted suitably in the engine system which concerns on this application The figure which shows the fall state of the cell voltage accompanying the temperature fall of the ammonia fuel solid oxide fuel cell

Hereinafter, engine systems 100 and 101 according to the present application will be described with reference to the drawings.
In the following description, the first embodiment and the second embodiment will be described.
In both of these embodiments, a combustor 3 (a kind of combustion means) and a nitrogen oxide remover 4 (a kind of nitrogen oxide removal means) are provided in the exhaust gas path 2 exhausted from the engine 1 in the order of description. Furthermore, an ammonia fuel solid oxide fuel cell 5 is provided which uses ammonia obtained by hydrolyzing urea water as fuel.

  One of the features of the present application is the exhaust heat generated in the engine 1, and the ammonia water is hydrolyzed to obtain ammonia by using heat that has been recovered from normal exhaust heat and lowered to 350 ° C. or lower. This is to use SOFC as fuel and to obtain electric power.

  1st embodiment is an example of the engine system 100 provided with the above-mentioned basic composition, and 2nd embodiment is the gas side and the liquid side in the decomposition product obtained in a gas-liquid mixed phase state by hydrolysis of urea water. The gas-liquid separator 6 (a kind of gas-liquid separation means) that separates the gas-side separator and the liquid-side separator is used in different applications. In the engine system 101 of this embodiment, the liquid side separation is further gasified and decomposed using engine exhaust heat, and hydrogen is mainly supplied to the anode 52 of the SOFC to obtain electric power. ing.

Hereinafter, it demonstrates in order.
[First embodiment]
FIG. 1 shows the system configuration of this embodiment.
This figure shows an exhaust gas treatment system for the exhaust gas generated from the engine 1 on the upper side, and shows a fuel supply configuration and a power extraction configuration in the SOFC 5 using ammonia as a fuel on the lower side.
The utilization form of the heat generated from the engine 1 and the combustor 3 is indicated by a thick solid line, and the introduction form of the fuel cell off-gas released from the SOFC 5 to the combustor 3 is indicated by a broken line. This route is referred to as an off-gas introduction route in the present application.

As shown in the figure, an engine system 100 includes an engine 1 that is operated by burning hydrocarbon fuel such as light oil or gasoline, and combustible substances in the exhaust gas are placed in an exhaust gas passage 2 through which the exhaust gas generated from the engine 1 flows. A combustor 3 that burns and a nitrogen oxide remover 4 that removes nitrogen oxides are provided in the order of description.
The combustor 3 is of a combustion burner type that receives a general fuel supply to form a flame in the chamber and burns it, or a catalyst containing a combustion catalyst such as platinum, vanadium, ruthenium, rhodium in the chamber It can be in a combustion form. As is well known, the nitrogen oxide remover 4 can employ a nitrogen oxide remover that receives ammonia supplied as a reducing agent and denitrates by a catalytic reaction. As the nitrogen oxide removal catalyst, an SCR catalyst (one or more of vanadium, molybdenum, tungsten, zeolite, and noble metal) is employed.

  Further, this system 100 includes urea water hydrolysis in which urea water supplied from a urea water storage 7 (a kind of urea water storage means) for storing urea water is hydrolyzed using heat generated from the engine 1. A vessel 8 (a kind of urea water hydrolysis means) and a SOFC 5 that uses ammonia produced by the urea water hydrolyzer 8 as fuel. In the SOFC 5, ammonia as fuel is led to the anode 52, and air containing oxygen which is separately supplied oxidizing gas is led to the cathode 53 to generate power.

Urea water hydrolysis unit 8, the normal temperature of the urea from the urea water reservoir _{7 ((NH 2) 2 CO} ) and water _(H 2 O) and urea water obtained as a mixture of _{((NH 2) 2 CO +} H 2 O) Is a hydrolyzer that hydrolyzes to ammonia (NH ₃ ) and carbon dioxide (CO ₂ ) by heating. The heat used for decomposition in the urea water hydrolyzer 8 is heat generated in the engine 1 as shown in the figure, and is heat reduced to about 350 ° C. Therefore, ammonia (NH ₃ ) obtained by the urea water hydrolyzer 8 is supplied to the SOFC 5 as a fuel.

  The SOFC 5 is configured as a stack (not shown) in which a large number of fuel cells 55 each provided with an anode 52 and a cathode 53 are sandwiched with a solid electrolyte 51 interposed therebetween, and as shown in FIG. Ammonia or hydrogen produced by the decomposition of ammonia is supplied, and an oxidizing gas (air) as an oxidant is supplied to the cathode 53.

The power generation reaction here is as follows when hydrogen is supplied as fuel.
Anode: H ₂ + O ²⁻ → H ₂ O + 2e ⁻
Cathode: O ₂ + 4e ⁻ → 2O ²⁻

On the other hand, when the fuel is supplied as ammonia, the cell reaction that occurs at the anode 52 and the cathode 53 is as shown in the drawing and is as follows.
Anode: 2NH ₃ + 3O ²⁻ → N ₂ + 3H ₂ O + 6e ⁻
Cathode: 3 / 2O ₂ + 6e ⁻ → 3O ²⁻

  As the material configuration of the solid electrolyte 51, the anode 52, and the cathode 53, a combination of materials previously adopted in the test of FIG. 4 can be adopted, and a general SOFC using ammonia as a direct fuel can be adopted.

  That is, as the material of the solid electrolyte 51, those known as SOFC solid oxide electrolytes can be used. For example, YSZ (yttria stabilized zirconia), ScSZ (scandia stabilized zirconia), and these zirconia Furthermore, oxygen ions such as zirconia powder doped with Ce, Al, etc., doped ceria powder such as SDC (Samaria doped ceria), GDC (gadria doped ceria), LSGM (lanthanum gallate) powder, bismuth oxide powder, etc. Conductive ceramic materials can be used. These solid oxide electrolytes may be used in combination of two or more if necessary.

  Further, the anode 52 may be mixed with cobalt in addition to nickel.

  The power generation of the SOFC 5 is a reaction in a high temperature range of about 600 to 800 ° C. In the engine system 100 according to the present application, in addition to the heat generation of the SOFC 5 itself, the heat from the engine 1 and the combustor 3 is used together. Maintain power generation. As a result, the heat generated in the engine 1 and the combustor 3 can be converted into electric power for effective use.

  The engine system 100 also includes an off-gas introduction path (shown by a broken line) that guides the fuel cell off-gas generated from the SOFC 5 to the combustor 3 provided in the exhaust gas path 2, and the fuel cell off-gas is connected to the combustor 3 and the nitrogen oxides. It is configured to be processed by the remover 4.

As shown in the figure, the fuel cell off-gas generated from the SOFC 5 using ammonia as a fuel, as shown in the figure, is hydrogen (H ₂ ), nitrogen (N ₂ ), carbon dioxide (CO ₂ ), water (H ₂ O), ammonia (NH ₃ ) and nitrogen oxide (NOx) may be included. Hydrogen, nitrogen, carbon dioxide, water, and nitrogen oxides are gases that are mainly contained in off-gas in a state where ammonia is decomposed and battery power generation is continued. Nitrogen oxides appear here because SOFC itself operates at a high temperature, but it is generated by local temperature rise at the mixing site of the anode exhaust gas and cathode exhaust gas provided in the battery and the subsequent process, although it is a small amount. Because there is. Ammonia may be included in the off-gas, for example, at the start of operation when the temperature of the SOFC 5 is not sufficiently raised or when the operation is lowered.

  Thus, the fuel cell off-gas may contain various gases depending on the operation stage on the SOFC side, and is released from the cell itself. However, in the system according to the present application, it is possible to ensure a good operation of the SOFC 5 without releasing unnecessary gas by using a processing mechanism originally provided for processing engine exhaust gas.

  Further, as shown by a thick solid line, the engine system 100 shown in FIG. 1 relates to the use of heat generated from the engine 1 and a first heat exchange unit 11 (a kind of first heat utilization means) used for heating the SOFC 5. The second heat exchanging section 12 (a kind of second heat utilization means) used for hydrolysis in the urea water hydrolyzer 8 is configured. Although simplified in the figure, as a heat exchanging unit 10 for recovering exhaust heat from the engine 1, a casing constituting the SOFC 5 (a casing for storing a SOFC stack, which is an assembly of the SOFC cells). The first heat exchanging part 11 for exchanging heat with the body, and the second heat exchanging part 12 for recovering the low-temperature side heat recovered from the first heat exchanging part 11 in terms of temperature. Such a thermal arrangement configuration can be realized by arranging it so as to be located on the high temperature side. For example, the casing is provided in a form that is thermally and directly connected to the engine jacket, the SOFC 5 is maintained at a high temperature, and the urea water hydrolyzer 8 is provided at a position away from the site, so that the heat on the high temperature side and the low temperature can be reduced. It is possible to appropriately use the heat on the side.

  Further, as shown in FIG. 1, the heat from the combustor 3 is also transferred to the first heat exchange unit 11 and the second heat exchange unit 12, and similarly generated in the combustor 3. The heat to be used can be used on the high temperature side and the low temperature side.

  That is, the first heat utilization means 11 uses heat on the high temperature side, and the second heat utilization means 12 uses the low-temperature side heat lowered by the heat utilization in the first heat utilization means 11.

  In the engine system 100, the heat generated in the engine 1 or the combustor 3 is used to hydrolyze urea water to obtain ammonia as fuel for the SOFC 5, so that the engine It is possible to obtain power by operating the SOFC 5 while 1 is operating.

Further, the SOFC 5 itself can continue to generate power upon receiving the supply of fuel.
Therefore, in the engine system 100 according to the present application, when the configuration in which the ammonia that has been hydrolyzed by the urea water hydrolyzer 8 is temporarily and partially stored is employed, the power generation by the engine power is stopped, and the SOFC 5 alone It is also possible to maintain the operation state and continue power generation for a predetermined time.

[Second Embodiment]
FIG. 2 shows the system configuration of this embodiment.
Also in this figure, the exhaust gas exhaust and treatment system generated from the engine 1 is shown on the upper side, and the fuel supply configuration and power extraction configuration in the SOFC 5 using ammonia as fuel are shown on the lower side. Further, as in FIG. 1, the introduction of the fuel cell off-gas released from the SOFC 5 into the combustor 3 is indicated by a broken line.

  Although this 2nd embodiment is provided with the gas-liquid separator 6, the supply system of each separated material isolate | separated by the said gas-liquid separator 6 is shown with the thin continuous line.

The use of heat generated from the engine 1 is indicated by a thick solid line as in FIG.
However, in this example, the heat generated in the engine 1 is generated by the decomposition of urea water, the gasification of the liquid-side separation separated by the gas-liquid separator 6, and the ammonia (gas) obtained by heating the liquid-side separation. It is also used for thermal decomposition. An outline of the mass transfer amount and the energy amount (necessary heat amount) required at each part in the case of adopting such a utilization form is shown as an example in FIG. In this mode of use, exhaust heat obtained when the SL diesel engine is rotated at 2000 rpm is assumed.

Hereinafter, the system configuration will be described in more detail.
The engine system 101 includes an engine 1 that is operated using light oil as fuel, and includes a combustor 3 and a nitrogen oxide remover 4 in the order of description in an exhaust gas path 2 through which exhaust gas generated from the engine 1 flows. Furthermore, there is no difference from the first embodiment in that the urea water reservoir 7, the urea water hydrolyzer 8, and the SOFC 5 are provided. The same applies to the use of the low-temperature side heat generated in the engine 1 in the urea water hydrolyzer 8.

Hereinafter, the characteristic configuration of the second embodiment will be described in order.
As can be seen from FIG. 2, the engine system 100 of the second embodiment includes a gas-liquid separator 6 (an example of a gas-liquid separator) that gas-liquid separates the decomposition product obtained by the urea water hydrolyzer 8. The liquid-side separation separated by the gas-liquid separator 6 is gasified by the heat generated from the engine 1 and supplied to the SOFC 5 as fuel.

  Further, the SOFC 5 includes a thermal decomposition unit 13 (an example of a thermal decomposition unit) that thermally decomposes ammonia that is fuel by heat generated from the engine 1, and hydrogen generated by ammonia decomposition in the thermal decomposition unit 13 is converted into the SOFC 5. A configuration for supplying to the anode 52 is employed.

  The pyrolysis section 13 contains at least one of ruthenium, nickel, cobalt, and iron as an ammonia decomposition catalyst, and is approximately 80% in a temperature range of approximately 200 ° C. or higher and almost 100% in a temperature range of 400 ° C. or higher. Is decomposed into hydrogen and nitrogen. Therefore, this thermal decomposition part 13 should just be kept in the temperature range of about 200 degreeC or more and 450 degrees C or less.

An example of the external configuration of the SOFC 5 provided with such a thermal decomposition unit 13 is shown in FIG.
The SOFC 5 has a configuration in which a substantially rectangular parallelepiped casing 5b is placed on a bottom plate 5a, and includes a plate-like thermal decomposition section 13 in accordance with the bottom shape of the SOFC 5. The thermal decomposition section 13 is provided with a path indicated by a broken zigzag line inside, decomposes ammonia NH ₃ supplied as fuel, and supplies it to the anode 52. Gases (fuel side and air side) that have finished the fuel cell reaction in the SOFC 5 are both SOFC off-gas (fuel electrode (anode) side) and SOFC off-gas (air electrode (cathode) side) via the thermal decomposition unit 13. , And discharged to the combustor 3 and the nitrogen oxide remover 4. As described above, the thermal decomposition unit 13 is modularized and integrated with the SOFC 5 to facilitate combination with other facilities (the engine 1, the combustor 3, and the like) and to improve heat transfer.

  Further, as shown by a thin solid line in FIG. 2, the gas-side separator (ammonia gas) separated by the gas-liquid separator 6 is configured to be supplied to the nitrogen oxide remover 4. The remover 4 stores one or more of vanadium, molybdenum, tungsten, zeolite, noble metal, etc. as a nitrogen oxide reduction catalyst, and is supplied with ammonia as a reducing agent to reduce nitrogen oxide (NOx). , Detoxify.

  As is apparent from the configuration described above, in the engine system 101 of the second embodiment, nitrogen oxide removal is performed using the gas-side separation separated by the gas-liquid separator 6 as a reducing agent, and the liquid-side separation is performed. Is gasified, supplied to the SOFC 5 as fuel, further decomposed by the thermal decomposition unit 13 and supplied to the anode 52 with approximately hydrogen. Of course, air, which is a gas containing oxygen as an oxidizing gas, is supplied to the cathode 53 side of the SOFC 5 to ensure good operation of the SOFC 5, and can be performed at the predetermined temperature described above with reference to FIG. As much power as possible can be obtained.

  Now, the gas-liquid separation by the gas-liquid separator 6 in this example is performed. The control setting of the separation conditions (control setting of temperature and pressure) is such that the amount of the gas-side separator is determined in the nitrogen oxide remover 4. On the other hand, the amount of reducing agent required is adjusted to the amount corresponding to the amount of fuel required as fuel in the SOFC 5. Here, the amount of urea water to be hydrolyzed when performing this operation is basically an amount corresponding to the sum of the necessary amount as the reducing agent and the necessary amount as the fuel. Accordingly, in the engine system 101, the amount of exhaust gas from the engine 1, the amount of nitrogen oxide corresponding to the amount of exhaust gas, and the amount of fuel (ammonia amount) required for the amount of power generated by the fuel cell 5 are input information. The operation controller 60 is provided so as to perform the hydrolysis and gas-liquid separation of urea water in accordance with these necessary amounts.

The second embodiment is characterized in that gas-liquid separation is performed. Therefore, in the present application, a control function part 61 that operates the gas-liquid separator 6 to meet the above operating conditions is referred to as “gas-liquid separation adjustment”. Called “means”.
With this configuration, the urea water is separately held, the urea water hydrolysis means and the gas-liquid separation means are provided, and ammonia reduction type nitrogen oxide treatment and power generation are performed in a predetermined engine 1 operation state. Can be executed well.

[Another embodiment]
Hereinafter, another embodiment of the present application will be listed.
A In the first embodiment, an example in which heat generated by the combustor 3 in addition to heat generated by the engine 1 is effectively used has been described. In the second embodiment, no particular mention was made regarding the heat of the combustor 3, but also in this form, the heat generated in the combustor 3 is heated by SOFC, ammonia is decomposed, and the liquid-phase-side separated gasification is obtained. You may use for the hydrolysis of urea water.

B In the first embodiment, no particular mention was made regarding the reducing agent used in the nitrogen oxide remover (SCR). However, as shown in the second embodiment, ammonia obtained from the urea water hydrolyzer 8 is used. Alternatively, it is also possible to use a conventional reducing agent supply system that uses a configuration that has been conventionally provided and mixes it with exhaust gas in the form of urea water.

C In the second embodiment, the pyrolysis unit 13 provided separately for the thermal decomposition of ammonia and attached to the SOFC casing is provided separately, but the anode constituting the solid oxide fuel cell is used as the anode. You may employ | adopt the structure which supplies ammonia gas directly.

  The heat generated from the engine or the combustion means or both of them is used effectively, and the processing mechanism for processing the exhaust gas exhausted from the engine is used to obtain ammonia as fuel for SOFC to supply power. An engine system capable of reducing defective components that may be contained in the exhaust gas as much as possible can be obtained.

1 Engine 2 Exhaust gas path 3 Combustor (combustion means)
4 Nitrogen oxide remover (nitrogen oxide removal means / ammonia reduction type nitrogen oxide removal means)
5 SOFC (ammonia fuel solid oxide fuel cell)
5a Bottom plate 5b Case 6 Gas-liquid separator (gas-liquid separation means)
7 Urea water reservoir (urea water storage means)
8 Urea water hydrolyzer (urea water hydrolysis means)
10 heat exchanger 11 1st heat exchange part (1st heat utilization means)
12 2nd heat exchange part (2nd heat utilization means)
13 Thermal decomposition part (thermal decomposition means)
51 Solid electrolyte 52 Anode (fuel electrode)
53 Cathode (Air electrode)
55 Fuel Cell 60 Operation Control Unit 61 Gas-Liquid Separation Adjusting Unit 100 Engine System 101 Engine System

Claims (11)

An engine operated by burning hydrocarbon fuel;
An engine system comprising combustion means for combusting combustibles in the exhaust gas and nitrogen oxide removing means for removing nitrogen oxides in the order of description in an exhaust gas path through which exhaust gas generated from the engine flows.
Urea water hydrolysis means for hydrolyzing urea water supplied from urea water storage means for storing urea water using heat generated from the engine and / or the combustion means;
An ammonia fuel solid oxide fuel cell using ammonia produced by the urea water hydrolysis means as a fuel,
An off-gas introduction path for guiding the fuel cell off-gas generated from the ammonia fuel solid oxide fuel cell to the combustion means;
An engine system that processes the fuel cell off-gas by the combustion means and the nitrogen oxide removal means.   2. The engine system according to claim 1, wherein the nitrogen oxide removing unit is an ammonia reduction type nitrogen oxide removing unit that uses ammonia generated by the urea water hydrolysis unit as a reducing agent. With respect to the use of heat generated from the engine or the combustion means or both,
A first heat utilization means used for heating the ammonia fuel solid oxide fuel cell; and a second heat utilization means used for hydrolysis in the urea water hydrolysis means,
3. The engine according to claim 1, wherein the first heat utilization unit uses high-temperature side heat, and the low-temperature side heat lowered by heat utilization in the first heat utilization unit is used in the second heat utilization unit. system. Gas-liquid separation means for gas-liquid separation of the decomposition product obtained by the urea water hydrolysis means,
The liquid side separation separated by the gas-liquid separation means is gasified by heat generated from the engine and / or the combustion means, and is supplied to the ammonia fuel solid oxide fuel cell as fuel. The engine system according to 1 or 2.   The ammonia fuel solid oxide fuel cell is provided with a thermal decomposition means for thermally decomposing ammonia as a fuel by heat generated from the engine and / or the combustion means, and hydrogen produced by the thermal decomposition means The engine system according to claim 4, wherein is supplied to an anode of a solid oxide fuel cell. The nitrogen oxide removing means is ammonia reducing nitrogen oxide removing means using ammonia produced by the urea water hydrolysis means as a reducing agent,
Gas-liquid separation means for gas-liquid separation of the decomposition product obtained by the urea water hydrolysis means,
The gas-side separation separated by the gas-liquid separation means is supplied as a reducing agent to the ammonia reduction nitrogen oxide removal means, and the liquid-side separation is generated from the engine and / or the combustion means. Gasified by heat and supplied to the ammonia fuel solid oxide fuel cell as fuel,
Regarding the gas-liquid separation by the gas-liquid separation means, the amount of the gas-side separation is the amount of reducing agent required by the ammonia reduction-type nitrogen oxide removal means, and the amount of the liquid-side separation is the ammonia fuel. The engine system according to claim 1, further comprising gas-liquid separation adjusting means for adjusting to an amount corresponding to the amount of fuel required in the solid oxide fuel cell.   The engine system according to any one of claims 1 to 3, wherein the engine is a gasoline engine or a diesel engine.   The engine system according to any one of claims 4 to 6, wherein the engine is a diesel engine. An engine operated by burning hydrocarbon fuel;
An engine system comprising combustion means for combusting combustibles in the exhaust gas and nitrogen oxide removing means for removing nitrogen oxide in the exhaust gas in the order of description in an exhaust gas path through which exhaust gas generated from the engine flows. Driving method,
Urea water hydrolysis means for hydrolyzing urea water supplied from urea water storage means for storing urea water using heat generated from the engine and / or the combustion means;
An ammonia fuel solid oxide fuel cell using ammonia produced by the urea water hydrolysis means as a fuel,
An off-gas introduction path for guiding a fuel cell off-gas generated from the ammonia fuel solid oxide fuel cell to the combustion means provided in the engine exhaust gas path;
The urea water from the urea water storage means is hydrolyzed by the urea water hydrolysis means using heat generated from the engine and / or the combustion means or both, and is also generated by the urea water hydrolysis means. An operation method of an engine system in which ammonia is used as a fuel to an ammonia fuel solid oxide fuel cell, and after the power generation by engine power is stopped, the ammonia fuel solid oxide fuel cell supplies electric power. An engine operated by burning hydrocarbon fuel;
An engine system comprising combustion means for combusting combustibles in the exhaust gas and nitrogen oxide removing means for removing nitrogen oxide in the exhaust gas in the order of description in an exhaust gas path through which exhaust gas generated from the engine flows. Driving method,
Urea water hydrolysis means for hydrolyzing urea water supplied from urea water storage means for storing urea water using heat generated from the engine and / or the combustion means;
An ammonia fuel solid oxide fuel cell using ammonia produced by the urea water hydrolysis means as a fuel,
An off-gas introduction path for guiding a fuel cell off-gas generated from the ammonia fuel solid oxide fuel cell to the combustion means provided in the engine exhaust gas path;
The nitrogen oxide removing means is ammonia reducing nitrogen oxide removing means using ammonia produced by the urea water hydrolysis means as a reducing agent,
Gas-liquid separation means for gas-liquid separation of the decomposition product obtained by the urea water hydrolysis means,
The gas-side separation separated by the gas-liquid separation means is supplied as a reducing agent to the ammonia reduction nitrogen oxide removal means, and the liquid-side separation is generated from the engine and / or the combustion means. Gasified by heat and supplied to the ammonia fuel solid oxide fuel cell as fuel,
Regarding the gas-liquid separation by the gas-liquid separation means, the amount of the gas-side separation is changed to the amount of reducing agent required by the ammonia reduction-type nitrogen oxide removal means, and the amount of the liquid-side separation is changed to the ammonia. A method for operating an engine system, which is adjusted to an amount corresponding to an amount of fuel required in a fuel solid oxide fuel cell. The ammonia fuel solid oxide fuel cell is provided with a thermal decomposition means for thermally decomposing ammonia as fuel by heat generated from the engine and / or the combustion means, and hydrogen is generated by the thermal decomposition means. The method for operating an engine system according to claim 10, wherein the engine system is supplied to an anode of a solid oxide fuel cell.

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