JP6652866B2 - Solid oxide fuel cell system - Google Patents

Description

The present invention is an ammonia storage unit in which an ammonia adsorption state in which ammonia is adsorbed at an ammonia adsorption temperature is stored, and an ammonia adsorption / desorption material that desorbs ammonia adsorbed at an ammonia desorption temperature higher than the ammonia adsorption temperature is stored.
The present invention relates to a solid oxide fuel cell system including a solid oxide fuel cell that receives ammonia supplied from the ammonia storage unit as fuel, and an exhaust gas path through which exhaust gas discharged from the solid oxide fuel cell flows.

At present, as a technology that is receiving attention, there is a technology for obtaining electric power using ammonia directly as fuel (Patent Documents 1 and 2). These technologies are noteworthy in terms of CO ₂ reduction and the like because ammonia does not contain carbon. Further, since no carbon deposit is generated on the battery electrode, the operation of the fuel cell can be stably continued.
As a fuel cell directly using ammonia as a fuel, there is a solid oxide fuel cell (hereinafter sometimes referred to as SOFC). Today, mainly at the anode electrode, ammonia is decomposed into hydrogen to reduce the output. Development is proceeding in a direction of avoiding a battery reaction (Patent Documents 3 and 4).

  On the other hand, Patent Document 5 discloses an invention relating to an ammonia adsorbing / desorbing agent (ammonia adsorbing / desorbing material in the present invention) in which a specific metal halide is combined, a separation method, and a storage method. The invention disclosed in this document provides a method for separating ammonia in which ammonia synthesized on-site can be efficiently separated by an adsorption separation method such as PSA or PTSA and can be further stored. At the time of separation, a mixture of calcium chloride and calcium bromide is used as the metal halide, and the metal halide in an ammonia-adsorbed state (ammonia complex of metal halide) is exposed to the pressure and temperature at which ammonia is desorbed. To desorb (separate) ammonia.

  The invention disclosed in Patent Document 6 relates to heat storage using a chemical heat storage material, and relates to a method for producing an ammonia complex-based chemical heat storage material capable of controlling a reaction temperature. The proposed manufacturing method is that after completely dissolving calcium chloride and calcium bromide in water, the aqueous solution is concentrated under heating and reduced pressure, and dried to obtain a calcium salt mixture. The ammonia adsorbing and desorbing material is added to ammonia (adsorption in the present invention) at an ammonia gas pressure of 1.2 atm and a temperature of -20 ° C to obtain a calcium salt mixture ammonia complex.

JP 2011-204416 A JP 2011-204418 A JP 2013-212117 A JP 2013-21118 A JP 2007-307558 A JP-A-6-136357

  As described above, the use of ammonia as a fuel for SOFCs has attracted attention today, but ammonia is usually handled in the form of liquid ammonia. When storing, transporting, and supplying ammonia in this form, pressurization is required for handling (1.0 MPa or more at ordinary temperature), and it is treated as a so-called high-pressure gas. Attempting to supply ammonia on-site with SOFC as a fuel requires a high-pressure tank for storing liquid ammonia. Considering the fact that SOFCs are being installed at various sites today, there is an obstacle to their widespread use. Becomes Also, in the case where the supply of ammonia is to be received as fuel, considering that the SOFC is an energy generating device, it is preferable to receive the supply of ammonia with as low an energy load as possible when supplying the fuel. No such technique has been proposed.

  Patent Documents 5 and 6 introduced above disclose the separation, storage, and supply of ammonia. However, when ammonia is used as a fuel, for example, the ammonia is slipped and discharged without being consumed by an energy generator. No indication is given as to how ammonia which may be treated.

  To explain this point in the SOFC system, a small amount of ammonia may be contained in the exhaust gas (exhaust gas) of the SOFC main body (main power generation unit of the solid oxide fuel cell) using ammonia as a fuel. Since ammonia cannot be released to the outside as it is, it is necessary to decompose and release it. However, ammonia decomposition requires thermal decomposition and oxidative decomposition, requiring a high temperature and consuming energy, which lowers the energy efficiency of the SOFC system in total. That is, in the case of using ammonia, the treatment of ammonia accompanying the use is always a problem, but a sufficient study has not been made in this regard.

  An object of the present invention is to provide an SOFC system that uses an ammonia directly or indirectly as a fuel and that can reduce the energy consumption required for the operation of the SOFC system as much as possible.

To achieve the above object, according to the present invention, there is provided an ammonia adsorbing / desorbing material which is maintained in an ammonia adsorbing state in which ammonia is adsorbed at an ammonia adsorbing temperature and desorbs the adsorbed ammonia at an ammonia desorbing temperature higher than the ammonia adsorbing temperature. An ammonia storage unit to be stored,
A solid oxide fuel cell that receives ammonia supplied from the ammonia storage unit as fuel,
A first characteristic configuration of a solid oxide fuel cell system including: an exhaust gas passage through which exhaust gas discharged from the solid oxide fuel cell flows;
In the exhaust gas passage, the temperature of the exhaust gas flowing through the exhaust gas passage is reduced and led to a heat supply unit that supplies heat to the ammonia storage unit, and the ammonia storage unit absorbs and desorbs the ammonia stored in the ammonia storage unit. An ammonia desorption operation means for setting an ammonia desorption temperature of the material, wherein the ammonia storage unit is an ammonia desorption unit.

  In this solid oxide fuel cell system, heat possessed by exhaust gas discharged from an SOFC is used to obtain ammonia as a fuel. On the other hand, for the storage of ammonia as a fuel, an ammonia adsorbing / desorbing material in an ammonia adsorbing state is used, and by raising the temperature of the ammonia adsorbing / desorbing material to an ammonia desorbing state (desorption temperature), fuel can be satisfactorily stored. Obtainable.

  Normally, the operating temperature of the SOFC is close to 700 ° C., and the temperature of the exhaust gas reaches this temperature range at the SOFC outlet. Regarding the exhaust heat of the exhaust gas of the SOFC, it can be used up to about 60 ° C. even if it is recovered as hot water. Usually, heat in a temperature range of about 100 ° C. to 150 ° C. may be discarded without being used.

In such a situation, in the present invention, as will be described later, by selecting an ammonia adsorbing / desorbing material, ammonia serving as a fuel of the SOFC is desorbed from its adsorption state and obtained by the SOFC from the ammonia storage unit. Becomes possible.
As a result, an SOFC system with a low energy load was obtained from the viewpoint of obtaining an ammonia fuel.

A second characteristic configuration of the present invention is:
The ammonia desorption operation means,
Exhaust gas temperature lowering means for lowering the temperature of the exhaust gas,
By mixing the high-temperature side exhaust gas before the temperature is reduced by the exhaust gas temperature reducing means and the low-temperature side exhaust gas after the temperature is reduced by the exhaust gas temperature reducing means, the mixed exhaust gas adjusted to the ammonia desorption temperature or higher is mixed. Equipped with a mixed exhaust gas generating means for desorption operation to be generated,
A mixed exhaust gas introduction path for guiding the mixed exhaust gas generated by the mixed exhaust gas generating means for desorption operation to the heat supply unit is provided.

  By providing the second characteristic configuration, both the high-temperature side exhaust gas and the low-temperature side exhaust gas are actively generated, and by appropriately mixing these, the temperature of the exhaust gas (mixed exhaust gas) used for ammonia desorption is provided. Can be appropriately controlled.

As a specific configuration of the mixed exhaust gas generating means for the desorption operation, as described in the third characteristic configuration of the present invention, the mixed exhaust gas generating means for the desorption operation is provided by a high-temperature exhaust gas path through which the high-temperature exhaust gas flows. A low-temperature side exhaust gas path through which the low-temperature side exhaust gas flows, and a merging portion where the gas flowing out from the high-temperature side exhaust gas path and the low-temperature side exhaust gas path merges,
The temperature of the mixed exhaust gas is set to be equal to or higher than the ammonia desorption temperature based on a quantitative ratio between the high-temperature exhaust gas and the low-temperature exhaust gas that are joined at the junction.

  By performing control based on the amount ratio, a highly reliable adjustment mechanism can be easily constructed using a flow adjustment valve, a three-way valve, and the like, which are commonly used and can adjust a flow rate.

Regarding the temperature control of the exhaust gas used for ammonia desorption described above,
An ammonia fuel supply amount control device that supplies ammonia fuel to the solid oxide fuel cell according to the amount of ammonia fuel required in accordance with the amount of power generation required for the solid oxide fuel cell,
It is preferable to include a mixed exhaust gas temperature control means for controlling the temperature of the mixed exhaust gas according to the amount of ammonia fuel supplied from the ammonia fuel supply amount control device.

  In the case of an SOFC, it is necessary to supply fuel in accordance with the amount of power generation, but at the same time, when an ammonia adsorbing / desorbing material is used as in the present invention, mixing is performed at a temperature at which ammonia desorption can be desorbed to the maximum. By operating such that the exhaust gas temperature control means secures the amount of fuel required by the ammonia fuel supply amount control device, it is possible to appropriately cope with the required power generation amount.

A fourth characteristic configuration of the present invention is:
The exhaust gas temperature lowering means is a hot water generating heat exchanger that receives heat held by the high temperature side exhaust gas to obtain hot water.

  As mentioned earlier, the SOFC exhaust gas temperature is high, but by recovering the heat held by the exhaust gas as hot water, the energy held by the SOFC exhaust gas can be used effectively, and the SOFC system can be used as a so-called cogeneration system. Can work.

A fifth characteristic configuration of the present invention is:
The ammonia adsorption / desorption material is a metal halide compound having an ammonia adsorption / desorption equilibrium temperature of 40 ° C. to 130 ° C. at standard atmospheric pressure.

By using this type of ammonia adsorbing / desorbing material, the ammonia storage unit serving as the ammonia desorbing unit can be constructed not as a high-pressure tank but as a tank capable of handling a pressure of about standard atmospheric pressure.
Furthermore, since the temperature as a heat supply medium is relatively low, the energy load is reduced.
Here, the ammonia adsorption / desorption material is described in terms of “equilibrium temperature for adsorption / desorption of ammonia at standard atmospheric pressure”. At a temperature lower than the equilibrium temperature, ammonia is adsorbed by contact with ammonia to change from an ammonia desorbed state to an ammonia adsorbed state, and at a temperature higher than the equilibrium temperature, the adsorbed ammonia is desorbed and deammified from the ammonia adsorption temperature. It will be in a detached state.
Since the metal halide compound forms a complex with ammonia, the "equilibrium temperature for ammonia adsorption / desorption at standard atmospheric pressure" is the coordination reaction equilibrium temperature of ammonia at standard atmospheric pressure.

Such a metal halide compound should be at least one selected from a halogenated Ba compound, a halogenated Ca compound, a halogenated Sr compound, and a halogenated Mn compound, as shown in the sixth characteristic configuration. Can be.
In the present specification, the metal name of the halogenated compound is described using a chemical symbol.

A seventh characteristic configuration of the present invention is:
The present invention is characterized in that an ammonia adsorbing section for accommodating an ammonia adsorbing / desorbing material for adsorbing ammonia contained in exhaust gas having been desorbed and discharged from the heat supply section is provided.

  In this solid oxide fuel cell system, as described above, even when the exhaust gas contains ammonia as a fuel (when the ammonia fuel slips), the ammonia is adsorbed without a large energy load. Can be adsorbed / removed and released to the outside.

An eighth characteristic configuration of the present invention is:
There is provided an ammonia adsorption operation means for setting the temperature of the ammonia adsorption / desorption material stored in the ammonia adsorption section to be equal to or lower than the ammonia adsorption temperature of the material.

  As described above, the behavior of the ammonia adsorbing / desorbing material changes depending on the temperature, but ammonia can be reliably adsorbed and removed at the ammonia adsorbing section by positive temperature control by the ammonia adsorbing operation means.

A ninth feature of the present invention is:
The ammonia adsorption operation means is a radiator that cools the heat held by the ammonia adsorption section by releasing the heat to the atmosphere.

  Cooling of the ammonia adsorbing section (ammonia adsorbing / desorbing material housed inside) can be easily realized with a radiator.

A tenth characteristic configuration of the present invention is:
Providing an ammonia adsorber for adsorbing and removing ammonia contained in the desorbed exhaust gas discharged from the heat supply unit,
The ammonia adsorption / desorption equilibrium temperature at standard atmospheric pressure is higher than the ammonia adsorption / desorption equilibrium temperature at standard atmospheric pressure of the ammonia adsorption / desorption material contained in the ammonia desorption unit. The point is that the metal compound is stored.

  As described above, the characteristics of the ammonia adsorbing / desorbing material stored in the ammonia adsorbing section are set to be higher in the ammonia adsorbing property and lower in the ammonia desorbing property than the ammonia adsorbing / desorbing material stored in the ammonia desorbing section. Thus, the operation of adsorbing the ammonia adsorbing / desorbing material stored in the ammonia adsorbing section can be ensured.

  As described in the eleventh feature of the present invention, the ammonia adsorbing / desorbing material disposed in the ammonia adsorbing section is a kind selected from a halogenated Co compound, a halogenated Mg compound, and a halogenated Ni compound. The above can be considered.

A twelfth characteristic configuration of the present invention is a radiator in which the exhaust gas temperature lowering means described above in the second characteristic configuration radiates heat held by the high-temperature side exhaust gas to the atmosphere to obtain the low-temperature side exhaust gas. On the point.

  In this configuration, the heat held by the exhaust gas is discarded without being recovered, but the SOFC system can be operated as a so-called mono-generation system to satisfy a predetermined time and a predetermined amount of power generation demand.

Regarding such exhaust gas temperature lowering means,
It is configured to be able to use a hot water generating heat exchanger that receives the heat held by the high temperature side exhaust gas to obtain hot water or a heat radiation heat exchanger that releases the heat held by the high temperature side exhaust gas to the atmosphere,
It is also preferable that the hot water generation heat exchanger and the heat radiation heat exchanger are exchangeable.

  By adopting this configuration, the SOFC system can be made into a cogeneration system or a monogeneration system by exchanging the heat exchanger, so that the demand for the system can be appropriately met.

A thirteenth feature of the present invention is:
Ammonia adsorbing and desorbing material for adsorbing ammonia contained in the desorbed exhaust gas discharged from the heat supply unit is provided, and an ammonia adsorbing and desorbing material is stored therein. Ammonia adsorption operation means for setting the temperature at or below the ammonia adsorption temperature of the material is provided,
A heat radiator that lowers the heat held by the heat receiving side heat medium introduced into the heat exchanger for generating hot water by releasing the heat to the atmosphere,
In the ammonia adsorption operation means,
A low-temperature-side heat-receiving medium introduction path that guides the heat-receiving-side heat medium whose temperature has been lowered by the radiator to the ammonia adsorption unit, and a heat exchange unit that cools the ammonia adsorption unit with the heat-receiving-side heat medium.
It is characterized in that a high-temperature-side heat-receiving medium introduction path is provided for returning the heat-receiving-side heat medium after receiving heat in the heat exchange section to a heat-receiving-side heat medium inlet of the heat exchanger for generating hot water.

  The SOFC system according to the present invention includes an ammonia desorption operation unit for ammonia desorption, and an ammonia adsorption operation unit for ammonia adsorption, thereby supplying ammonia fuel and adsorbing and removing ammonia contained in exhaust gas. Although it is possible to surely cope with the removal, it is preferable to cool the ammonia adsorption section in the latter ammonia adsorption operation.

  Therefore, using a radiator provided to recover the exhaust heat held by the exhaust gas as hot water, the heat receiving side heat medium sent from the radiator is guided to the ammonia adsorption section, and then returned to the hot water generating heat exchanger. Thus, the temperature of the ammonia adsorbing portion can be reduced and the heat can be recovered from the exhaust gas with one radiator.

FIG. 1 is a diagram showing a configuration of a first embodiment of a solid oxide fuel cell system according to the present invention. FIG. 2 is a diagram showing a configuration of a second embodiment of the solid oxide fuel cell system according to the present invention. The figure which shows the structure of 3rd Embodiment of the solid oxide fuel cell system which concerns on this invention.

  Hereinafter, the SOFC system 100 according to the present invention will be described with reference to the drawings.

  In the embodiment described below, a part of the SOFC system 100 is an ammonia storage and supply device 1, and the main components of the SOFC system 100 are an ammonia desorbing unit 2 in which a first ammonia adsorbing / desorbing material A1 is stored, and a second ammonia A housing 10 (corresponding to an ammonia fuel tank) having therein an ammonia adsorbing section 3 in which an adsorbing / desorbing material A2 is stored, and an ammonia desorbing operation means M1 for desorbing ammonia from the first ammonia adsorbing / desorbing material A1 And ammonia adsorption operation means M2 for adsorbing ammonia on the second ammonia adsorption / desorption material A2.

The housing 10 that is the main body of the ammonia storage and supply device 1
(1) The SOFC system 100 in a state where the first ammonia adsorbing / desorbing material A1 in the ammonia adsorbing state is stored in the ammonia desorbing section 2 and the second ammonia adsorbing / desorbing material A2 in the ammonia desorbing state is stored in the ammonia adsorbing section 3 Attached to
(2) After supplying ammonia as fuel to the SOFC 101 and using it for power generation,
(3) The first ammonia adsorbing / desorbing material A1 in the ammonia desorbing state is removed from the ammonia desorbing section 2 while the second ammonia adsorbing / desorbing material A2 in the ammonia adsorbing state is stored in the ammonia adsorbing section 3.
The used ammonia adsorption / desorption materials A1 and A2 after use are separately regenerated.
This regeneration process is an ammonia adsorption process for bringing the first ammonia adsorption / desorption material A1 into contact with ammonia to adsorb the ammonia, and the second ammonia adsorption / desorption material A2 is a desorption process for desorbing ammonia. To perform this operation, the housing 10 has a structure in which the ammonia adsorbing / desorbing materials A1 and A2 can be taken out and stored (not shown).
Therefore, the housing 10 substantially serves as an ammonia fuel tank of the SOFC system 100.

  The SOFC system 100 according to the present invention receives the supply of ammonia as a fuel from the ammonia storage / supply device 1 and, while performing power generation, discharges the exhaust gas e into a predetermined portion of the ammonia storage / supply device 1 (ammonia desorption unit 2, ammonia adsorption Part 3) and discharge to the outside. Then, in receiving ammonia as fuel, the exhaust gas e discharged from the SOFC system 100 is used.

  Hereinafter, the housing 10 including the ammonia desorbing unit 2 and the ammonia adsorbing unit 3 as the ammonia storage unit, which is the main component of the ammonia storage and supply device 1, will be described first, and the operation of the operation units M1 and M2 for operating these units. I will explain about.

Housing as Ammonia Fuel Tank As shown in FIG. 1, the ammonia storage and supply device 1 is configured to have a substantially cylindrical housing 10, and the inside of the housing 10 is vertically divided into two chambers. ing.
These two chambers are an ammonia desorbing section 2 in which the first ammonia adsorbing / desorbing material A1 according to the present invention is stored, and an ammonia adsorbing section 3 in which the second ammonia adsorbing / desorbing material A2 is stored.

  As can be seen from the figure, this casing 10 is provided with an ammonia outlet 4 for supplying ammonia to the SOFC 101, and an exhaust gas inlet 5 through which the exhaust gas e discharged from the SOFC 101 is cooled and introduced. And a treated exhaust gas outlet 6 from which a treated exhaust gas e4 from which ammonia has been removed via the ammonia storage and supply device 1 flows out.

  In the present embodiment, the ammonia desorbing section 2 employs a shell-and-tube heat exchange structure, includes a large number of heat transfer tubes 21 (tubes) in an outer cylinder 20 (shell), and includes an outer cylinder 20 and a heat transfer tube. The space formed between the heat transfer unit 21 and the first ammonia adsorption / desorption material A1 is configured as an ammonia adsorption / desorption material storage chamber R, and the heat transfer tube 21 is configured as a heat supply unit r through which exhaust gas e from the SOFC 101 flows. Have been. In the illustrated example, a distribution chamber 7 is provided at the inlet of the ammonia desorbing section 2, and the exhaust gas e flows into each heat transfer tube 21 from the distribution chamber 7. Here, the exhaust gas e does not contact the first ammonia adsorption / desorption material A1.

  The exhaust gas inlet 5 is connected to the distribution chamber 7, and the inflowing exhaust gas e is distributed into the plurality of heat transfer tubes 21 and flows therein.

  The ammonia delivery port 4 is connected to the ammonia adsorbing / desorbing material storage chamber R, and the ammonia desorbed from the first ammonia adsorbing / desorbing material A1 stored in the chamber R flows out.

  The exhaust gas e supplied with heat from the plurality of heat transfer tubes 21 flows into the ammonia adsorption section 3. Ammonia adsorbing / desorbing material A2 is stored in the ammonia adsorbing section 3, and the ammonia contained in the exhaust gas e can be removed from the second ammonia adsorbing / desorbing material A2 by setting the exhaust gas channel length to a predetermined channel length. Can be removed by adsorption.

  A treated exhaust gas outlet 6 is connected to an upper portion of the ammonia adsorbing section 3, and discharges the treated exhaust gas e4 to the atmosphere in an ammonia-free state.

  The above is the description of the housing 10 provided with the ammonia desorbing section 2 and the ammonia adsorbing section 3. Hereinafter, ammonia will be described using the ammonia adsorbing and desorbing materials A1 and A2 stored in the sections 2 and 3, respectively. A configuration for supplying as fuel of the SOFC 101 and removing ammonia that may be contained in the exhaust gas e will be described.

Ammonia desorption operation means M1
A portion surrounded by a broken line in the lower part of the center of FIG. 1 is a functional portion constituting the ammonia desorption operation means M1 (the same in FIGS. 2 and 3).
The ammonia desorbing section 2 is provided with a number of heat transfer tubes 21 as heat supply portions r, and the exhaust gas of the SOFC 101 is provided to the heat transfer tubes 21 so that the first ammonia adsorbing / desorbing material A1 satisfactorily desorbs the adsorbed ammonia. e is allowed to flow in at a temperature equal to or higher than the ammonia desorption temperature of the first ammonia adsorption / desorption material A1. This is the function of the ammonia desorption operation means M1. For example, FIG. 1 exemplarily shows that the temperature range of the exhaust gas e is 50 to 60 ° C.
The detailed structure of the ammonia desorption operation means M1 will be described in the section of the SOFC system 100 according to each embodiment.

Ammonia adsorption operation means M2
On the other hand, what is indicated by a broken line in the left part of FIG. 1 is a functional part constituting the ammonia adsorption operation means M2 (the same in FIG. 3). In the second embodiment shown in FIG. 2, it is indicated by a broken line extending from the bottom of the figure to the left side portion.
As is clear from these figures, by providing a cooling mechanism beside the ammonia adsorbing section 3, the second ammonia adsorbing / desorbing material A2 is set to a temperature lower than its ammonia adsorbing temperature. This is the function of the ammonia adsorption operation means M2. For example, FIG. 1 exemplarily shows that this temperature range is 30 to 40 ° C.
The detailed structure of the ammonia adsorption operation means M2 will be described in the section of the SOFC system 100 according to each embodiment.

First ammonia adsorption / desorption material A1
In the ammonia desorbing section 2, as a first ammonia adsorbing / desorbing material A1, an ammonia adsorption state in which a metal halide compound having an ammonia adsorption / desorption equilibrium temperature at standard atmospheric pressure of 40 ° C. to 130 ° C. adsorbs ammonia is used. Is stored in. That is, at least one selected from a halogenated Ba compound, a halogenated Ca compound, a halogenated Sr compound, and a halogenated Mn compound is stored in the form of a metal halide ammine complex which forms a complex with ammonia. As a result, in the operating state of the SOFC 101, the exhaust gas e is supplied to the heat transfer tube 21, and the temperature is raised to the ammonia desorption temperature, whereby ammonia is desorbed, and ammonia can be supplied to the SOFC 101 as fuel.

Second ammonia adsorption / desorption material A2
The ammonia adsorption / desorption equilibrium temperature at standard atmospheric pressure of the ammonia adsorption / desorption material A2 is higher than the ammonia adsorption / desorption equilibrium temperature of the first ammonia adsorption / desorption material A1 at standard atmospheric pressure. Ni chloride, which is an example of a high metal halide compound, is stored. This Ni chloride is stored in an ammonia-desorbed state (a single unit that is not an ammine complex) from which ammonia has been desorbed. In the operating state of the SOFC 101, the exhaust gas e flows into the ammonia adsorbing section 3, and ammonia is contained in the exhaust gas e. If it is contained, it adsorbs ammonia to form a Ni-ammine chloride complex.
The ammonia adsorption / desorption equilibrium temperature of Ni chloride at standard atmospheric pressure is about 180 ° C.

  The particle diameter of the ammonia adsorbing / desorbing material described above (both the first ammonia adsorbing / desorbing material A1 and the second ammonia adsorbing / desorbing material A2) is not particularly limited, but is usually about 5 μm to 100 mm, preferably 10 μm to 30 mm. Can be used. Not only granules but also sheets or honeycombs may be formed. Porous materials such as silica, alumina and zeolite can be used by being supported on a high surface area substance.

SOFC System Hereinafter, the entire SOFC system 100, the ammonia desorption operation means M1, the ammonia adsorption operation means M2 whose functions have been briefly described above, and the first ammonia adsorption / desorption material A1 and the second ammonia adsorption / desorption material A1 used in each embodiment will be described. The desorbing material A2 will be described in accordance with each embodiment.

  The first embodiment (FIG. 1) and the second embodiment (FIG. 2) are examples in which the SOFC system 100 is a cogeneration system, and the third embodiment (FIG. 3) is an example in which the SOFC system 100 is a monogeneration system. .

  The temperature of the exhaust gas e discharged from the SOFC 101 and introduced into the ammonia desorption unit 2 differs between the case where the SOFC system 100 is a cogeneration system and the case where the SOFC system 100 is a monogeneration system. The temperature in the operating state of the SOFC system 100 is exemplarily shown.

  As can be seen from these figures, the temperature of the low-temperature side exhaust gas e2 differs between the cogeneration system and the monogeneration system. Therefore, the ammonia adsorption / desorption material used as the first ammonia adsorption / desorption material A1 is different. On the other hand, the second ammonia adsorption / desorption material A2 uses a common ammonia adsorption / desorption material.

  The SOFC system 100 includes an SOFC 101 that receives, as fuel, ammonia supplied from the ammonia desorbing unit 2 in which the ammonia adsorbing / desorbing material A1 is stored, and an exhaust gas passage 102 through which exhaust gas e discharged from the SOFC 101 flows. 102 is provided with an ammonia desorption operation means M1 for lowering the temperature of the exhaust gas e to an appropriate temperature and supplying it to the heat supply unit r provided in the ammonia desorption unit 2.

  In the figure, a single cell is schematically depicted in an SOFC 101 described as an ammonia fuel SOFC. As is well known, a single cell of the SOFC 101 includes a fuel electrode 101b and an air electrode 101c with a solid electrolyte (solid oxide electrolyte) 101a interposed therebetween. Fuel is supplied to the fuel electrode 101b side and fuel is supplied to the air electrode 101c side. Oxygen-containing gas (specifically, air) is supplied to generate power.

  In a fuel cell using ammonia as a fuel as in the present invention, when ammonia is used directly as fuel, ammonia is directly guided to the fuel electrode 101b, decomposed at the fuel electrode 101b, and power is generated by hydrogen and oxygen. When ammonia is used as an indirect fuel, ammonia is decomposed by a reforming reaction before being sent to the fuel electrode 101b, and is sent to the fuel electrode 101b as hydrogen to generate electricity.

  When ammonia is used as the fuel as described above, for example, when the amount of power generation changes abruptly, ammonia slip occurs, and the exhaust gas may include ammonia.

[First Embodiment]
As shown in FIG. 1, the SOFC system 100 according to the first embodiment includes an exhaust heat recovery circuit 50 for recovering heat of the exhaust gas e of the SOFC as hot water. The exhaust heat recovery circuit 50 is configured as a circulation path through which a heat receiving side heat medium (water w in this example) circulates between the hot water storage tank 51 and the cogeneration heat exchanger 52, and cogeneration heat exchange. The heat recovered from the exhaust gas e by the vessel 52 is stored in the hot water storage tank 51 in the form of hot water, and is used for hot water supply, heating, additional cooking of bathtub water, and the like. In the figure, the circuit on the heat utilization side is not shown.

In the exhaust heat recovery circuit 50, a heat medium pump 53 and a radiator 54 are provided in a forward path 50a from the hot water storage tank 51 to the cogeneration heat exchanger 52 for the above purpose. Therefore, while extracting water from the hot water storage tank 51 and sending it to the cogeneration heat exchanger 52, exhaust heat recovery can be performed to obtain hot water.
Here, the radiator 54 is used for the purpose of adjusting the temperature of the medium in the cogeneration heat exchanger 52 so that the heat is recovered by the heat receiving side heat medium in an appropriate state.

  The above is the configuration of the exhaust heat recovery side mainly including the cogeneration heat exchanger 52, and the heat supply side heat medium (the exhaust gas e in this example) is passed through the cogeneration heat exchanger 52. Temperature decreases. Accordingly, the exhaust gas passage 102 is provided with the cogeneration heat exchanger 52 as exhaust gas temperature lowering means.

Hereinafter, the configuration of the ammonia desorption operation means M1 described above will be described.
By mixing the high-temperature side exhaust gas e1 before the temperature is reduced by the cogeneration heat exchanger 52 with the low-temperature side exhaust gas e2 after the temperature is reduced, the mixed exhaust gas e3 adjusted to the ammonia desorption temperature or higher is mixed. A mixed exhaust gas generating means Mm for desorption operation, and a mixed exhaust gas introduction path 102a for guiding the mixed exhaust gas e3 generated by the mixed exhaust gas generating means Mm for desorption operation to the exhaust gas inlet 5 of the ammonia storage and supply device 1. It has.

  Specifically, the mixed exhaust gas generating means Mm for the desorption operation includes a high-temperature exhaust gas passage 102b through which the high-temperature exhaust gas e1 flows and a low-temperature exhaust gas passage 102c through which the low-temperature exhaust gas e2 flows. It has a merging portion 102d where the gas flowing out from the low-temperature side exhaust gas passage 102c merges. The temperature of the mixed exhaust gas e3 is adjusted based on the quantitative ratio of the high-temperature side exhaust gas e2 and the low-temperature side exhaust gas e1 merged at the merging portion 102d. It is higher than the desorption temperature. As shown in FIG. 1, the temperature of the high-temperature side exhaust gas e1 is about 200 ° C., the temperature of the low-temperature side exhaust gas e2 is about 60 ° C., and the temperature of the mixed exhaust gas e3 is 50 to 60 ° C.

  Regarding the temperature control of the mixed exhaust gas e3, a detector s for detecting the temperature near the inlet and the temperature near the outlet of the ammonia desorbing section 2 is provided, and based on the detected temperature, this temperature is set to a predetermined target temperature. The temperature control controller TIC generates an opening signal and adjusts the opening of the valve V1 of the high-temperature side exhaust gas flow path 102b, the opening of which can be adjusted, so that the first ammonia adsorbing / desorbing material A1 is desorbed. (Supply of ammonia as fuel to the SOFC 101) can be performed favorably.

First ammonia adsorption / desorption material A1
In the first embodiment, the ammonia desorbing section 2 stores Sr chloride as a Sr ammine chloride complex (octammine Sr chloride) to which ammonia is adsorbed (the same as in the second embodiment). This ammonia complex is stored at a standard atmospheric pressure, and the exhaust gas e is supplied to the heat transfer tube 21 with the operation of the SOFC 101 to desorb ammonia. Incidentally, the ammonia adsorption / desorption equilibrium temperature of standard Sr chloride at standard atmospheric pressure is about 40 ° C.
Therefore, by setting the temperature of the mixed exhaust gas e3 to about 50 to 60 ° C., ammonia can be desorbed from the Sr chloride in the ammonia adsorption state and supplied to the SOFC 101.

The exhaust gas e that has passed through the ammonia desorption section 2 is guided to the ammonia adsorption section 3.
The temperature of the ammonia adsorbing section 3 is determined by the amount of heat supplied for ammonia desorption in the ammonia desorbing section 2 and the heat release of the radiator (specifically, the radiating fan 9) described above as the ammonia adsorption operating means M2. Although controlled by the amount of heat, the ammonia in the exhaust gas can be adsorbed and removed by setting the temperature of the ammonia adsorbing section 3 to be equal to or lower than the temperature at which the second ammonia adsorbing / desorbing material A2 adsorbs ammonia. That is, the air-cooling fan 9 includes a temperature sensor s for detecting the temperature of the ammonia adsorption section 3, a temperature control controller TIC for transmitting operation control information to the air-cooling fan 9 based on the output of the temperature sensor s, and an air-cooling fan 9. The adsorption state is maintained.

  As described above, the ammonia adsorption section 3 stores Ni chloride Ni as the second ammonia adsorption / desorption material A2. The ammonia adsorption / desorption equilibrium temperature of this Ni chloride is higher than that of Sr chloride, and the temperature of the ammonia adsorption section 3 (and consequently the temperature of the mixed exhaust gas e3) is reduced to about 30 to 40 ° C. The ammonia in the exhaust gas e is adsorbed by the Ni chloride in the state, and the clean exhaust gas e can be released to the outside.

[Second embodiment]
The second embodiment is different from the first embodiment, which is an example of a cogeneration system, in that the ammonia adsorbing operation means M2 is not provided independently as in the first embodiment, but from the radiator 54 provided in the exhaust heat recovery circuit 50. This is an example in which the heat-receiving-side heat medium sent out (water w in this example) is used for cooling the ammonia adsorption unit 3.
The same reference numerals are given to the same devices as in the first embodiment.
In this example, only the configuration of the ammonia adsorption operation means M2 is different from that of the first embodiment.

As shown in FIG. 2, in the second embodiment, the radiator 54 provided in the exhaust heat recovery circuit 50 is used to configure the ammonia adsorption operation means M2. In other words, the heat absorbing medium 3 is cooled by the heat receiving side heat medium w and the low temperature side heat receiving medium introduction path 91 for guiding the heat receiving side heat medium w, which has been cooled by the heat radiator 54 to the atmosphere, to the ammonia adsorbing section 3. And a heat exchange coil 90 for returning the heat receiving side heat medium w after receiving heat by the heat exchange coil 90 to the heat receiving side heat medium inlet 52a of the cogeneration heat exchanger 52 which is a heat exchanger for generating hot water. By providing the heat receiving medium introduction passage 92, the ammonia adsorption section 3 can work well.
In this configuration, the heat exchange coil 90 serves as a heat exchange unit for cooling, and the temperature of the heat receiving side heat medium (water w in this example) sent from the radiator 54 provided in the exhaust heat recovery circuit 50 is set to the first temperature. In addition to lowering the amount than in the embodiment, the circulation amount is increased so that the ammonia adsorption in the ammonia adsorbing section 3 is appropriately performed.

[Third embodiment]
The SOFC system 100 according to the third embodiment shown in FIG. 3 is a monogeneration system that does not recover heat from exhaust gas e from the SOFC 101.

  Therefore, unlike the first and second embodiments, the exhaust heat recovery circuit 50 for recovering the exhaust heat is not provided, and the heat of the exhaust gas e discharged from the SOFC 101 is radiated to the atmosphere by the radiator 500. . Therefore, in this embodiment, the low temperature side exhaust gas path 102c is a simple heat radiation path for lowering the temperature of the exhaust gas e flowing therethrough, and the radiator 500 is an exhaust gas temperature lowering means.

  In the example of the monogeneration system, the temperature of the mixed exhaust gas e3 is set to 100 to 130 ° C. as shown in FIG.

  Therefore, Mn chloride is employed as the first ammonia adsorption / desorption material A1 stored in the ammonia desorption section 2. Since the ammonia adsorption / desorption equilibrium temperature of Mn chloride is about 86 ° C., even when the temperature of the mixed exhaust gas e3 is set to about 100 to 130 ° C., ammonia is desorbed from the Mn chloride ammine complex in the ammonia adsorption state, and the SOFC 101 Can be supplied to

  The configuration of the ammonia adsorbing section 3, the configuration of the second ammonia adsorbing / desorbing material A2 housed in the relevant portion, and the configuration of the ammonia adsorbing operation means M2 for the adsorbing operation are the same as those in the first embodiment.

  By the way, also in this embodiment, there is provided a high-temperature side exhaust gas path 102b through which the high-temperature side exhaust gas e1 flows, and a low-temperature side exhaust gas path 102c through which the low-temperature side exhaust gas e2 flows. And a temperature of the mixed exhaust gas e3 is set to be equal to or higher than the ammonia desorption temperature based on a quantitative ratio of the high-temperature exhaust gas e1 and the low-temperature exhaust gas e2 that are merged at the junction 102d. The basic configuration of the first embodiment is followed.

However, in this embodiment, with respect to the temperature control of the ammonia desorbing unit 2, a detector s for detecting the temperature near the inlet and the temperature near the outlet of the ammonia desorbing unit 2 is provided, and based on the detected temperature of the detector s. A flow control type three-way valve V2 capable of controlling the opening degree of the high temperature side or the low temperature side or both of them at the merging portion 102d to adjust the flow ratio of the high temperature side exhaust gas e1 and the low temperature side exhaust gas e2, The temperature of the mixed exhaust gas e3 is adjusted.
Even with such a configuration, the mixed exhaust gas generating means Mm for the desorption operation can be configured.

[Another embodiment]
(1) In the above-described embodiment, as an example of a combination of the first ammonia adsorbing / desorbing material A1 and the second ammonia adsorbing / desorbing material A2, the first ammonia adsorbing / desorbing material A1 is used as a first ammonia adsorbing / desorbing material A1. A metal halide having a desorption equilibrium temperature of 40 ° C. or more and 130 ° C. or less is used as the second ammonia adsorption / desorption material A2, and a halogen having a higher ammonia adsorption / desorption equilibrium temperature at standard atmospheric pressure than the first ammonia adsorption / desorption material. Although an example in which a combination of metal halide compounds is employed has been shown, in such a combination, the ammonia adsorption / desorption equilibrium temperature of the second ammonia adsorbing / desorbing material A2 is higher than that of the first ammonia adsorbing / desorbing material A1 in the relationship between the two. If the temperature is higher than the ammonia adsorption / desorption equilibrium temperature, the former A1 exhibits the desorption performance and the latter A2 exhibits the adsorption performance under the same temperature environment. Therefore, it can be adopted.
As in the above-described embodiment, the temperature of the ammonia desorbing section 2 is actively controlled relatively by providing the ammonia desorbing means M1, and the ammonia adsorbing section 3 is provided by the ammonia adsorbing means M2. This is especially true if the temperature can be controlled relatively low.

When the combination of the ammonia adsorbing and desorbing material is 130 ° C. under standard atmospheric pressure, the first ammonia adsorbing and desorbing material A1 is made of a halogenated Ba compound, a halogenated Ca compound, a halogenated Sr compound, and a halogenated Mn. The second ammonia adsorbing / desorbing material A2 may be at least one selected from a halogenated Co compound, a halogenated Mg compound, and a halogenated Ni compound.
Also, when the combination of the ammonia adsorbing / desorbing material is 100 ° C. under the standard atmospheric pressure, the combination of the first ammonia adsorbing / desorbing material A1 and the second ammonia adsorbing / desorbing material A2 is the same as described above.

  In the case where the metal halide compound is chloride, the coordination reaction of ammonia will be described. For Ba chloride, Ca chloride and Sr chloride, ammonia starts to be desorbed at about 50 to 60 ° C. The ammonia adsorption / desorption equilibrium temperature (coordination reaction equilibrium temperature of ammonia) at standard atmospheric pressure is 86 ° C., 135 ° C. for Co chloride, 140 ° C. for Mg chloride, and 180 ° C. for Ni chloride.

(2) As a configuration of the mixed exhaust gas temperature control means for controlling the temperature of the mixed exhaust gas, the ammonia fuel for supplying the ammonia fuel to the SOFC 101 in accordance with the required amount of the ammonia fuel corresponding to the power generation amount required for the SOFC 101 The mixed exhaust gas temperature control means may be configured to include a supply amount control device (mass flow controller) and control the temperature of the mixed exhaust gas according to the amount of ammonia fuel supplied from the ammonia fuel supply amount control device.

(3) Regarding the first embodiment which is a cogeneration system and the third embodiment which is a monogeneration system, in the former system, as the exhaust gas temperature lowering means, heat received by the high-temperature side exhaust gas is received to generate hot water. A heat exchanger for cogeneration (an example of a heat exchanger for hot water generation) is used, and in the latter system, a radiator (radiation heat exchanger) that radiates heat held by the high-temperature side exhaust gas to the atmosphere is used as means for lowering exhaust gas temperature. In the SOFC system according to the present invention, the positions of the former heat exchanger for generating hot water and the latter are substantially the same in the system of the radiator. It is preferable that the heat exchanger and the heat exchanger can be exchanged.
By adopting this configuration, it is possible to easily switch between the cogeneration system and the monogeneration system by exchanging the two.

  As an SOFC system using ammonia directly or indirectly as a fuel, an SOFC system capable of minimizing energy consumption required for operation of the SOFC system as much as possible was provided.

1. Ammonia storage and supply device 2. Ammonia desorption unit (ammonia storage unit)
3 Ammonia adsorption section 4 Ammonia outlet 5 Exhaust gas inlet 6 Treated exhaust gas outlet 7 Distribution chamber 9 Cooling fan (radiator)
10 Case 20 Outer cylinder 21 Heat transfer tube 50 Exhaust heat recovery circuit 50a Outgoing path 51 Hot water storage tank 52 Cogeneration heat exchanger (hot water generation heat exchanger, exhaust gas temperature lowering means)
53 heat medium pump 54 radiator 90 heat exchange coil (heat exchange part)
91 Low-temperature side heat receiving medium introduction path 92 High-temperature side heat reception medium introduction path 100 Solid oxide fuel cell system (SOFC system)
101 Solid oxide fuel cell (SOFC)
102 Exhaust gas passage 102a Mixed exhaust gas passage 102b High-temperature exhaust gas passage 102c Low-temperature exhaust gas passage 102d Converging section 500 Radiator (exhaust gas temperature lowering means)
A1 First ammonia adsorption / desorption material A2 Second ammonia adsorption / desorption material M1 Ammonia desorption operation means M2 Ammonia adsorption operation means Mm Desorption operation mixed exhaust gas generation means R Ammonia adsorption / desorption material storage chamber TIC Temperature controller V1 Valve V2 3 Way valve e Exhaust gas e1 High temperature side exhaust gas e2 Low temperature side exhaust gas e3 Mixed exhaust gas e4 Treated exhaust gas r Heat supply unit s Detector

Claims (6)

An ammonia storage unit that is maintained in an ammonia adsorption state in which ammonia is adsorbed at an ammonia adsorption temperature, and stores an ammonia adsorbing / desorbing material that desorbs ammonia adsorbed at an ammonia desorption temperature higher than the ammonia adsorption temperature,
A solid oxide fuel cell that receives ammonia supplied from the ammonia storage unit as fuel,
An exhaust gas path through which exhaust gas discharged from the solid oxide fuel cell flows, and a solid oxide fuel cell system comprising:
In the exhaust gas passage, the temperature of the exhaust gas flowing through the exhaust gas passage is reduced and led to a heat supply unit that supplies heat to the ammonia storage unit, and the ammonia storage unit absorbs and desorbs the ammonia stored in the ammonia storage unit. Ammonia desorption operation means for setting the ammonia desorption temperature of the material, wherein the ammonia storage unit is an ammonia desorption unit, and adsorbs ammonia contained in exhaust gas after desorption operation discharged from the heat supply unit. A solid oxide fuel cell system provided with an ammonia adsorbing section for accommodating an ammonia adsorbing / desorbing material . The ammonia desorption operation means,
Exhaust gas temperature lowering means for lowering the temperature of the exhaust gas,
By mixing the high-temperature side exhaust gas before the temperature is reduced by the exhaust gas temperature reducing means and the low-temperature side exhaust gas after the temperature is reduced by the exhaust gas temperature reducing means, the mixed exhaust gas adjusted to the ammonia desorption temperature or higher is mixed. Equipped with a mixed exhaust gas generating means for desorption operation to be generated,
2. The solid oxide fuel cell system according to claim 1, further comprising a mixed exhaust gas introduction passage that guides the mixed exhaust gas generated by the mixed exhaust gas generating device for the desorption operation to the heat supply unit. 3. The exhaust gas temperature lowering means, the hot-side exhaust gas is heat to heat the hot water-producing heat exchanger to obtain a hot water held claim 2 Symbol placement of the solid oxide fuel cell system. Ammonia adsorption-desorption material accommodated in the ammonia desorption unit, any one of claims 1 to 3 ammonia adsorption-desorption equilibrium temperature at normal atmospheric pressure is a halogenated metal compound to 40 ℃ above 130 ° C. or less Item 8. The solid oxide fuel cell system according to Item 1. Providing an ammonia adsorber for adsorbing and removing ammonia contained in the desorbed exhaust gas discharged from the heat supply unit,
The ammonia adsorption / desorption equilibrium temperature at standard atmospheric pressure is higher than the ammonia adsorption / desorption equilibrium temperature at standard atmospheric pressure of the ammonia adsorption / desorption material contained in the ammonia desorption unit. The solid oxide fuel cell system according to claim 4, wherein a metal compound is stored. Ammonia adsorbing and desorbing material for adsorbing ammonia contained in the desorbed exhaust gas discharged from the heat supply unit is provided, and an ammonia adsorbing and desorbing material is stored therein. Ammonia adsorption operation means for setting the temperature at or below the ammonia adsorption temperature of the material is provided,
A heat radiator that lowers the heat held by the heat receiving side heat medium introduced into the heat exchanger for generating hot water by releasing the heat to the atmosphere,
In the ammonia adsorption operation means,
A low-temperature-side heat receiving medium introduction path that guides the heat-receiving-side heat medium that has been cooled by the radiator to the ammonia adsorption section,
A heat exchange unit that cools the ammonia adsorption unit with the heat receiving side heat medium,
4. The solid oxide fuel cell system according to claim 3, further comprising a high-temperature-side heat-receiving medium introduction path that returns the heat-receiving-side heat medium after receiving the heat in the heat exchange unit to a heat-receiving-side heat medium inlet of the hot water generating heat exchanger. 5. .

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