JP2017168404A - Solid oxide type fuel battery system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an SOFC system capable of reducing the energy consumption required for the operation of the SOFC system as much as possible as an SOFC system using ammonia directly or indirectly as fuel.SOLUTION: In a system configured to include an ammonia storage portion 2 for storing an ammonia adsorption/desorption material A1 for desorbing adsorbed ammonia at an ammonia desorption temperature higher than an ammonia adsorption temperature, a solid oxide type fuel battery 101 for accepting ammonia as fuel, and an exhaust gas passage 102 through which exhaust gas e discharged from the solid oxide type fuel battery 101 flows, the temperature of the exhaust gas e flowing through the exhaust gas passage 102 is lowered, and the exhaust gas e is led to a heat supply portion r for supplying heat to the ammonia storage portion 2 to set the ammonia storage portion 2 at the ammonia desorption temperature.SELECTED DRAWING: Figure 1

Description

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

Currently, there is a technique that obtains electric power using ammonia as a direct fuel as a technique that is attracting attention (Patent Documents 1 and 2). These techniques 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 continued stably.
As a fuel cell using ammonia as a direct fuel, there is a solid oxide fuel cell (hereinafter sometimes referred to as SOFC). Today, the anode side electrode mainly decomposes ammonia into hydrogen to reduce the output. Development is progressing in a direction to avoid the battery reaction (Patent Documents 3 and 4).

  On the other hand, Patent Document 5 describes an invention relating to an ammonia adsorbing / desorbing agent (ammonia adsorbing / desorbing material in the present invention), a separation method and a storage method, which are combined with a specific metal halide. The invention disclosed in this document provides an ammonia separation method in which ammonia synthesized on-site can be efficiently separated by an adsorption separation method such as PSA or PTSA, and can also be stored. During separation, a mixture of calcium chloride and calcium bromide is used as the metal halide, and the metal halide in the ammonia adsorption 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 the reaction temperature. In the proposed production method, after calcium chloride and calcium bromide are completely dissolved in water, the aqueous solution is concentrated under heating and reduced pressure and dried to obtain a calcium salt mixture. The ammonia adsorption / desorption material) was added with 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 2013-2111117 A JP2013-211118A JP 2007-307558 A JP-A-6-136357

  As described above, today, attention has been focused on adopting ammonia as a fuel for SOFC, but ammonia is usually handled in the form of liquid ammonia. When ammonia is stored, transported, and supplied in this form, pressurization is required for handling (1.0 MPa or more at room temperature), which is a so-called high-pressure gas. In order to supply ammonia on-site with SOFC as a fuel, a high-pressure tank for storing liquid ammonia is required, and considering that SOFC is being installed at various sites today, it is an obstacle in terms of its spread. It becomes. In addition, when trying to receive supply of ammonia as fuel, considering that SOFC is an energy generating device, it is preferable to supply ammonia with a low energy load as much as possible. No such technology 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, it is slipped and discharged without being consumed by an energy generator. There is no indication as to how to treat ammonia that may be present.

  In terms of this point, the SOFC system will explain a small amount of ammonia in the exhaust gas (exhaust gas) of the SOFC main body (main power generation part of the solid oxide fuel cell) that uses ammonia as a fuel. Since ammonia cannot be released to the outside as it is, it must be decomposed and released. However, because ammonia decomposition is thermal decomposition / oxidative decomposition, high temperature is required and energy is consumed, and the energy efficiency of the SOFC system is lowered in total. That is, when ammonia is used, the treatment of ammonia accompanying the use of the ammonia always becomes a problem. However, sufficient studies have not been made in this regard.

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

In order to achieve the above object, an ammonia adsorption / desorption material according to the present invention is maintained in an ammonia adsorption state where ammonia is adsorbed at an ammonia adsorption temperature and desorbs ammonia adsorbed at an ammonia desorption temperature higher than the ammonia adsorption temperature. An ammonia storage part to be stored;
A solid oxide fuel cell that accepts ammonia supplied from the ammonia storage unit as fuel; and
A first characteristic configuration of a solid oxide fuel cell system including an exhaust gas path through which exhaust gas discharged from the solid oxide fuel cell flows is as follows:
In the exhaust gas path, the temperature of the exhaust gas flowing through the exhaust gas path is lowered and led to a heat supply part that supplies heat to the ammonia storage part, and the ammonia storage part is accommodated in the ammonia storage part. There is provided an ammonia desorption operation means having an ammonia desorption temperature of the material, and the ammonia storage part is an ammonia desorption part.

  In this solid oxide fuel cell system, in order to obtain ammonia as a fuel, the heat stored in the exhaust gas discharged from the SOFC is used. On the other hand, storage of ammonia as fuel uses an ammonia adsorption / desorption material that is in an ammonia adsorption state, and by raising the temperature of this ammonia adsorption / desorption material to an ammonia desorption state (desorption temperature), the fuel is improved. Can be obtained.

  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 SOFC exhaust gas, it can be used up to about 60 ° C. even if recovered as hot water. Usually, heat in a temperature range of about 100 ° C. to 150 ° C. may be discarded without being used.

For this situation, in the present invention, by selecting an ammonia adsorbing / desorbing material as will be shown later, ammonia serving as SOFC fuel is desorbed from its adsorbed state, and is obtained from the ammonia storage section by SOFC. Is possible.
As a result, from the viewpoint of obtaining ammonia fuel, an SOFC system with a low energy load could be obtained.

The second characteristic configuration of the present invention is:
The ammonia desorption operation means comprises
Exhaust gas temperature lowering means for lowering the temperature of the exhaust gas;
A mixed exhaust gas adjusted to be equal to or higher than the ammonia desorption temperature by mixing the high temperature side exhaust gas before the temperature reduction by the exhaust gas temperature reduction means and the low temperature side exhaust gas after the temperature reduction by the exhaust gas temperature reduction means. Comprising a mixed exhaust gas generating means for desorption operation to generate,
There is provided a mixed exhaust gas introduction path for guiding the mixed exhaust gas generated by the desorption operation mixed exhaust gas generating means to the heat supply unit.

  By providing the second characteristic configuration, the temperature of the exhaust gas (mixed exhaust gas) to be used for ammonia desorption by actively generating both the high temperature side exhaust gas and the low temperature side exhaust gas and appropriately mixing them. Can be controlled appropriately.

As a specific configuration of the mixed exhaust gas generating means for desorption operation, as described in the third characteristic configuration of the present invention, the mixed exhaust gas generating means for desorption operation is provided with a high temperature side exhaust gas passage through which the high temperature side 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 the quantitative ratio of the high temperature side exhaust gas and the low temperature side exhaust gas joined at the junction.

  By using the control based on the quantity ratio, it is possible to easily construct a highly reliable adjustment mechanism using a commonly used flow rate adjustment valve capable of adjusting the flow rate, a three-way valve, or the like.

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

  In SOFC, it is necessary to supply fuel according to the amount of power generation. At the same time, when using an ammonia adsorbing / desorbing material as in the present invention, mixing is performed at a temperature at which ammonia desorption can be maximized. By ensuring the exhaust gas temperature control means and operating the ammonia fuel supply amount control device so as to secure the required fuel amount, it is possible to satisfactorily cope with the required power generation amount.

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

  As previously indicated, the exhaust gas temperature of SOFC is high, but by recovering the heat stored in the exhaust gas as hot water, the energy stored in the SOFC exhaust gas can be used effectively, making the SOFC system a so-called cogeneration system. Can work.

The 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. or higher and 130 ° C. or lower at standard atmospheric pressure.

By using this type of ammonia adsorbing / desorbing material, the ammonia storage part serving as the ammonia desorbing part can be constructed with a tank that can handle a pressure of about standard atmospheric pressure, not as a high-pressure tank.
Furthermore, since the temperature as the heat supply medium is also relatively low, the energy load is reduced.
Here, regarding the ammonia adsorption / desorption material, regarding the “ammonia adsorption / desorption equilibrium temperature at standard atmospheric pressure”, the temperature at which the characteristics of the ammonia adsorption / desorption material change from adsorption to desorption under standard atmospheric pressure. At a temperature lower than the equilibrium temperature, the ammonia is adsorbed by contact with ammonia to change from the ammonia desorption state to the ammonia adsorption state, and at a temperature higher than the equilibrium temperature, the adsorbed ammonia is desorbed to desorb the ammonia from the ammonia adsorption temperature. It becomes a separated state.
Since the metal halide compound forms a complex with ammonia, the “ammonia adsorption / desorption equilibrium temperature at standard atmospheric pressure” is the coordination reaction equilibrium temperature of ammonia at standard atmospheric pressure.

As shown in the sixth feature configuration, such a metal halide compound is at least one selected from a halogenated Ba compound, a halogenated Ca compound, a halogenated Sr compound, and a halogenated Mn compound. Can do.
In the present specification, metal names of halogenated compounds are described using chemical symbols.

The seventh characteristic configuration of the present invention is
An ammonia adsorbing part for storing an ammonia adsorbing / desorbing material that adsorbs ammonia contained in the exhaust gas after desorption operation discharged from the heat supply part is provided.

  In this solid oxide fuel cell system, as described above, even when ammonia, which is a fuel, is contained in exhaust gas (when ammonia fuel slips), ammonia is not adsorbed to the adsorbing portion without a large energy load. Can be adsorbed / removed and released to the outside.

The eighth feature 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 part to be equal to or lower than the ammonia adsorption temperature of the material.

  As described above, the behavior of the ammonia adsorption / desorption material changes depending on the temperature, but ammonia can be reliably adsorbed / removed by the ammonia adsorption part by the active temperature control by the ammonia adsorption operation means.

The ninth feature of the present invention is
The ammonia adsorption operation means is a heat radiator that cools the heat held by the ammonia adsorption part by radiating the heat to the atmosphere.

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

The tenth feature of the present invention is
An ammonia adsorption part for adsorbing and removing ammonia contained in the desorbed exhaust gas discharged from the heat supply part is provided,
The ammonia adsorption / desorption equilibrium temperature at the standard atmospheric pressure in the ammonia adsorption section is higher than the ammonia adsorption / desorption equilibrium temperature at the standard atmospheric pressure of the ammonia adsorption / desorption material stored in the ammonia desorption section. The metal compound is stored.

  The characteristics of the ammonia adsorbing / desorbing material stored in the ammonia adsorbing part as described above shall be higher in ammonia adsorbing property and lower in ammonia desorbing property than the ammonia adsorbing / desorbing material stored in the ammonia desorbing part. Thus, it is possible to ensure the adsorption operation with the ammonia adsorption / desorption material accommodated in the ammonia adsorption part.

  As described in the eleventh feature of the present invention, the ammonia adsorbing / desorbing material disposed in such an ammonia adsorbing portion is a kind selected from a halogenated Co compound, a halogenated Mg compound, and a halogenated Ni compound. This can be done.

The twelfth characteristic configuration of the present invention is a radiator that obtains the low-temperature side exhaust gas by radiating the heat held by the high-temperature side exhaust gas to the atmosphere by the exhaust gas temperature lowering means described in the second characteristic configuration. In the point.

  In this configuration, the heat stored in the exhaust gas is discarded without being recovered, but the SOFC system can be operated as a so-called monogeneration system, and a predetermined amount of power generation demand can be satisfied at a predetermined time.

Regarding such exhaust gas temperature lowering means,
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-dissipating heat exchanger that radiates the heat held by the high-temperature side exhaust gas to the atmosphere can be used,
It is also preferable that the hot water generating heat exchanger and the heat radiating heat exchanger are exchangeable.

  If this configuration is adopted, the SOFC system can be co-generated or mono-generated by exchanging the heat exchanger, and the system demand can be appropriately met.

The thirteenth feature of the present invention is
An ammonia adsorption / desorption material for accommodating an ammonia adsorption / desorption material that adsorbs ammonia contained in the exhaust gas after desorption operation exhausted from the heat supply unit is provided, and an ammonia adsorption / desorption material accommodated in the ammonia adsorption unit. An ammonia adsorption operation means for setting the temperature to be equal to or lower than the ammonia adsorption temperature of the material,
A radiator that lowers the heat held by the heat receiving side heat medium introduced into the heat exchanger for hot water generation by releasing it into the atmosphere,
In the ammonia adsorption operation means,
A low temperature side heat receiving medium introduction path for guiding the heat receiving side heat medium lowered in temperature by the radiator to the ammonia adsorbing part, a heat exchanging part for cooling the ammonia adsorbing part by the heat receiving side heat medium,
A high temperature side heat receiving medium introduction path is provided for returning the heat receiving side heat medium received by the heat exchanging section to the heat receiving side heat medium inlet of the hot water generating heat exchanger.

  In the SOFC system according to the present invention, ammonia desorption operation means is provided for ammonia desorption, and ammonia adsorption operation means is provided for ammonia adsorption. Although it can respond reliably for removal, it is preferable to cool the ammonia adsorption part in the latter ammonia adsorption operation.

  Therefore, a heat radiator provided for recovering the exhaust heat held in the exhaust gas as hot water is used, the heat receiving side heat medium sent from the heat radiator is guided to the ammonia adsorption part, and then returned to the hot water generating heat exchanger. Thereby, the temperature reduction of the ammonia adsorption part and heat recovery from the exhaust gas can be performed with one radiator.

The figure which shows the structure of 1st Embodiment of the solid oxide fuel cell system which concerns on this invention. The figure which shows the structure of 2nd Embodiment of the solid oxide fuel cell system which concerns on this invention. The figure which shows the structure of 3rd Embodiment of the solid oxide fuel cell system which concerns on this invention.

  Hereinafter, an 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 the ammonia storage and supply device 1, and the ammonia desorption part 2 in which the first ammonia adsorbing / desorbing material A1 is housed and the second ammonia as its main components. A housing 10 (corresponding to an ammonia fuel tank) provided with an ammonia adsorbing portion 3 in which the adsorbing / desorbing material A2 is housed, 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.

And the housing | casing 10 which is the main body of this ammonia storage supply apparatus 1 is as follows.
(1) The SOFC system 100 in a state in which the first ammonia adsorption / desorption material A1 in the ammonia adsorption state is accommodated in the ammonia desorption part 2 and the second ammonia adsorption / desorption material A2 in the ammonia desorption state is accommodated in the ammonia adsorption part 3. Attached to the
(2) After supplying ammonia to SOFC 101 as fuel and being used for power generation,
(3) The first ammonia adsorption / desorption material A1 in the ammonia desorption state is accommodated in the ammonia desorption portion 2, and the second ammonia adsorption / desorption material A2 in the ammonia adsorption state is removed in the state of being accommodated in the ammonia adsorption portion 3.
The ammonia adsorption / desorption materials A1 and A2 after use are separately regenerated.
This regeneration process is an ammonia adsorption process in which the first ammonia adsorption / desorption material A1 is brought into contact with ammonia to adsorb the ammonia, and the second ammonia adsorption / desorption material A2 is a desorption process in which ammonia is desorbed. In order to perform this operation, the housing 10 has a structure in which the ammonia adsorption / desorption materials A1 and A2 can be taken out and stored (not shown).
Accordingly, the housing 10 is substantially an ammonia fuel tank of the SOFC system 100.

  The SOFC system 100 according to the present invention receives supply of ammonia as a fuel from the ammonia storage and supply device 1 and generates power while generating the exhaust gas e from a predetermined portion (ammonia desorption portion 2 and ammonia adsorption) of the ammonia storage and supply device 1. To 3) and discharged to the outside. And in receiving ammonia as fuel, the exhaust gas e discharged from the SOFC system 100 is used.

  Hereinafter, the casing 10 having the ammonia desorption part 2 and the ammonia adsorption part 3 as the ammonia storage part which is the main body of the ammonia storage and supply device 1 will be described first, and the operation means M1 and M2 for operating these parts will be described. The explanation is advanced.

Housing as an ammonia fuel tank As shown in FIG. 1, the ammonia storage and supply device 1 includes a substantially cylindrical housing 10, and the housing 10 is divided into two chambers in the vertical direction. ing.
These two chambers are an ammonia desorption part 2 in which the first ammonia adsorption / desorption material A1 according to the present invention is accommodated and an ammonia adsorption part 3 in which the second ammonia adsorption / desorption material A2 is accommodated.

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

  In this example, the ammonia desorption part 2 employs a shell and tube type heat exchange structure, and includes a large number of heat transfer tubes 21 (tubes) in the outer cylinder 20 (shell), and the outer cylinder 20 and the heat transfer tubes. The space formed between the heat transfer tube 21 and the heat transfer tube 21 is configured as a heat supply portion r through which the exhaust gas e from the SOFC 101 flows. Has been. In the example shown in the figure, a distribution chamber 7 is provided at the inlet portion of the ammonia desorption section 2, and the exhaust gas e flows from the distribution chamber 7 into the heat transfer tubes 21. Here, the exhaust gas e does not come into contact with 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 and introduced into a large number of heat transfer tubes 21.

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

  The exhaust gas e after being heated from the multiple heat transfer tubes 21 flows into the ammonia adsorption unit 3. The ammonia adsorbing section 3 stores a second ammonia adsorbing / desorbing material A2, and by setting the exhaust gas flow path length to a predetermined flow path length, ammonia that may be contained in the exhaust gas e is removed from the second ammonia adsorbing / desorbing material A2. It can be adsorbed and removed.

  A treated exhaust gas outlet 6 is connected to the upper part of the ammonia adsorbing section 3, and the treated exhaust gas e <b> 4 is discharged to the atmosphere in an ammonia-free state.

  The above is the description of the housing 10 provided with the ammonia desorbing part 2 and the ammonia adsorbing part 3. Hereinafter, ammonia is absorbed and desorbed using the ammonia adsorbing / desorbing materials A1 and A2 housed in the parts 2 and 3, respectively. A configuration for supplying ammonia as the 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 functional portion constituting the ammonia desorption operation means M1 is shown by being surrounded by a broken line at the lower part of the center of FIG. 1 (the same applies to FIGS. 2 and 3).
The ammonia desorption section 2 is provided with a large number of heat transfer tubes 21 as a heat supply section r, and the exhaust gas of the SOFC 101 is connected to the heat transfer tubes 21 so that the first ammonia adsorbing / desorbing material A1 can desorb the ammonia in the adsorbed state well. 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 operating means M2
On the other hand, the left part of FIG. 1 surrounded by a broken line is a functional part constituting the ammonia adsorption operation means M2 (same in FIG. 3). In 2nd Embodiment shown in FIG. 2, it has shown with the broken line over the left side site | part from the bottom of the same figure.
As can be seen from these figures, the second ammonia adsorbing / desorbing material A2 is set to be equal to or lower than the ammonia adsorption temperature by providing a cooling mechanism beside the ammonia adsorbing portion 3. 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 also be described in the section of the SOFC system 100 according to each embodiment.

1st ammonia adsorption / desorption material A1
In the ammonia desorption part 2, an ammonia adsorption state in which a metal halide compound having an ammonia adsorption / desorption equilibrium temperature at a standard atmospheric pressure of 40 ° C. or more and 130 ° C. or less adsorbs ammonia as the first ammonia adsorption / desorption material A1 It is stored in. That is, any one or more selected from a halogenated Ba compound, a halogenated Ca compound, a halogenated Sr compound, and a halogenated Mn compound are stored in the form of a metal halide ammine complex that 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 ammonia is desorbed by raising the temperature to the ammonia desorption temperature, so that ammonia can be supplied to the SOFC 101 as fuel.

Second ammonia adsorption / desorption material A2
In the ammonia adsorbing section 3, as the second ammonia adsorption / desorption material A2, the ammonia adsorption / desorption equilibrium temperature at the standard atmospheric pressure is higher than the ammonia adsorption / desorption equilibrium temperature at the standard atmospheric pressure of the first ammonia adsorption / desorption material A1. Ni chloride which is an example of a high metal halide compound is accommodated. This Ni chloride is stored in an ammonia desorbed state (a simple substance that is not an ammine complex) from which ammonia has been desorbed, and in the operating state of the SOFC 101, the exhaust gas e flows into the ammonia adsorption unit 3, and the ammonia is contained in the exhaust gas e. When it is contained, ammonia is adsorbed 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 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 in particle size, but is usually about 5 μm to 100 mm, preferably 10 μm to 30 mm. You can use the one of the degree. It may be formed not only in a granular form but also in a sheet form or on a honeycomb, and a porous body such as silica, alumina, zeolite or the like can be supported on a high surface area substance and used.

SOFC System Hereinafter, the entire SOFC system 100, the ammonia desorption operation means M1, the ammonia adsorption operation means M2, and the first ammonia adsorption / desorption material A1 and the second ammonia adsorption used in each embodiment, which have been briefly described above, are described below. The desorbing material A2 will be described according to 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 a monogeneration system is used. .

  Since the temperature of the exhaust gas e discharged from the SOFC 101 and introduced into the ammonia desorption part 2 is different between the case where the SOFC system 100 is cogeneration and the case where the SOFC system 100 is used as a monogeneration system, the present invention is provided at a predetermined position in each figure. 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 ammonia supplied from the ammonia desorption part 2 in which the ammonia adsorbing / desorbing material A1 is stored as a fuel, and an exhaust gas path 102 through which the exhaust gas e discharged from the SOFC 101 flows. Reference numeral 102 denotes an ammonia desorption operation means M1 that lowers the temperature of the exhaust gas e to an appropriate temperature and supplies it to the heat supply unit r provided in the ammonia desorption unit 2.

  In the figure, a single cell is schematically drawn in SOFC 101 described as ammonia fuel SOFC. As is well known, a single cell of SOFC 101 is configured to include a fuel electrode 101b and an air electrode 101c with a solid electrolyte (solid oxide electrolyte) 101a interposed therebetween, with fuel on the fuel electrode 101b side and fuel on the air electrode 101c side. An oxygen-containing gas (specifically air) is supplied to generate electricity.

  In a fuel cell using ammonia as a fuel as in the present invention, when ammonia is directly used as fuel, ammonia is directly guided to the fuel electrode 101b, and is decomposed at the fuel electrode 101b to generate power using 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 power.

  Thus, when ammonia is used as the fuel, for example, when the amount of power generation changes abruptly, ammonia slip may occur, and ammonia may be contained in the exhaust gas.

[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 the heat of the SOFC exhaust gas e 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 performs heat generation for cogeneration. The heat recovered from the exhaust gas e in 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 preparation of bathtub water, and the like. In the figure, the circuit on the heat utilization side is not shown.

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

  The above is the configuration of the exhaust heat recovery side mainly composed of the cogeneration heat exchanger 52, and the heat supply side heat medium (exhaust gas e in this example) passes through the cogeneration heat exchanger 52. The temperature drops. 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 lowered by the cogeneration heat exchanger 52 and the low temperature side exhaust gas e2 after the temperature is lowered, the mixed exhaust gas e3 adjusted to be equal to or higher than the ammonia desorption temperature is obtained. A mixed exhaust gas introduction path 102a that includes a mixed exhaust gas generation means Mm for desorption operation to be generated and guides the mixed exhaust gas e3 generated by the mixed exhaust gas generation means Mm for desorption operation to the exhaust gas inlet 5 of the ammonia storage supply device 1 It has.

  Specifically, the mixed exhaust gas generation means Mm for desorption operation includes 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. A combined portion 102d where the gas flowing out from the low temperature side exhaust gas path 102c joins is combined, and the temperature of the mixed exhaust gas e3 is adjusted to ammonia based on the quantitative ratio between the high temperature side exhaust gas e2 and the low temperature side exhaust gas e1 that are merged in the combined portion 102d. Above 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 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 this temperature is configured to be a predetermined target temperature based on the detected temperature. Desorption from the first ammonia adsorbing / desorbing material A1 by generating an opening signal with the temperature control controller TIC and adjusting the opening of the valve V1 that can be adjusted in the opening provided in the high temperature side exhaust gas passage 102b. (Supply of ammonia as fuel to the SOFC 101) can be performed satisfactorily.

1st ammonia adsorption / desorption material A1
In the first embodiment, the ammonia desorbing unit 2 stores Sr chloride as a Sr ammine chloride complex (octammine Sr chloride) adsorbing ammonia (the same in the second embodiment). This ammonia complex is stored at standard atmospheric pressure, and the exhaust gas e is supplied to the heat transfer tube 21 along with the operation of the SOFC 101 to desorb ammonia. Incidentally, the ammonia adsorption / desorption equilibrium temperature of 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 unit 2 is guided to the ammonia adsorption unit 3.
The temperature of the ammonia adsorbing unit 3 depends on the amount of heat provided for ammonia desorption in the ammonia desorbing unit 2 and the discharge of the radiator (specifically, the heat dissipating 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 adsorption part 3 to be equal to or lower than the temperature at which the second ammonia adsorption / desorption material A2 adsorbs ammonia. That is, a temperature sensor s for detecting the temperature of the ammonia adsorption unit 3, a temperature control controller TIC for sending operation control information to the air cooling fan 9 based on the output of the temperature sensor s, and the air cooling fan 9 are provided. The adsorption state is maintained.

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

[Second Embodiment]
The second embodiment is an example of a cogeneration system. In the first embodiment, the ammonia adsorption operation means M2 is not provided independently as in the first embodiment, and the radiator 54 provided in the exhaust heat recovery circuit 50 is used. In this example, the heat receiving side heat medium sent out (water w in this example) is used for cooling the ammonia adsorption unit 3.
The same symbols are used for 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, a radiator 54 provided in the exhaust heat recovery circuit 50 is used to configure the ammonia adsorption operation means M2. In other words, the low temperature side heat receiving medium introduction path 91 for guiding the heat receiving side heat medium w, which has been reduced in temperature by radiating the heat held by the radiator 54, to the ammonia adsorbing section 3, and the ammonia adsorbing section 3 is cooled by the heat receiving side heat medium w. And a heat exchange coil 90 that receives the heat receiving side heat medium w received by the heat exchange coil 90 to the heat receiving side heat medium inlet 52a of the cogeneration heat exchanger 52 that is a heat exchanger for hot water generation. By providing the heat receiving medium introduction path 92, the ammonia adsorption part 3 can work well.
In this configuration, the heat exchange coil 90 serves as a cooling heat exchange unit, 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. While lowering than the case of the embodiment, the circulation amount is increased so that ammonia adsorption in the ammonia adsorption unit 3 is appropriately performed.

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

  Therefore, unlike the first and second embodiments, the exhaust heat recovery circuit 50 for exhaust heat recovery is not provided, and the heat of the exhaust gas e exhausted 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 dissipation path for reducing the temperature of the exhaust gas e flowing through the low temperature side exhaust gas path 102c, and the radiator 500 is an exhaust gas temperature lowering means.

  In the example of this 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 adsorbing / desorbing material A1 stored in the ammonia desorbing section 2. Since the ammonia adsorption / desorption equilibrium temperature of Mn chloride is about 86 ° C., even if the temperature of the mixed exhaust gas e3 is about 100 to 130 ° C., ammonia is desorbed from the Mn chloride ammine complex in the ammonia adsorption state, and the SOFC 101 It becomes possible to supply to.

  The configuration of the ammonia adsorbing unit 3, the configuration of the second ammonia adsorbing / desorbing material A2 accommodated in the part, and the ammonia adsorbing operation means M2 for the adsorbing operation are the same as in the first embodiment.

  In this embodiment as well, 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 are provided, and the high temperature side exhaust gas path 102b and the low temperature side exhaust gas path 102c flow out. A gas merging portion 102d is formed, and the 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 side exhaust gas e1 and the low temperature side exhaust gas e2 merged in the merging portion 102d. The basic configuration of the first embodiment is followed.

However, in this embodiment, for temperature control of the ammonia desorption unit 2, a detector s for detecting the temperature near the inlet and the temperature near the outlet of the ammonia desorption unit 2 is provided, and based on the detected temperature of the detector s. The 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 is provided at the junction 102d to adjust the flow rate ratio between 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 in such a configuration, the mixed exhaust gas generation means Mm for desorption operation can be configured.

[Another embodiment]
(1) In the above embodiment, as an example of the combination of the first ammonia adsorbing / desorbing material A1 and the second ammonia adsorbing / desorbing material A2, as the first ammonia adsorbing / desorbing material A1, ammonia adsorption / desorption at standard atmospheric pressure can be performed. A halogenated metal compound having a desorption equilibrium temperature of 40 ° C. or higher and 130 ° C. or lower is used as the second ammonia adsorption / desorption material A2, and the ammonia adsorption / desorption equilibrium temperature at standard atmospheric pressure is higher than that of the first ammonia adsorption / desorption material. In this example, the ammonia adsorption / desorption equilibrium temperature of the second ammonia adsorption / desorption material A2 is the same as that of the first ammonia adsorption / desorption material A1. 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 becomes possible to employ.
As in the embodiments described so far, the ammonia desorption operation means M1 is provided to actively manage the temperature of the ammonia desorption part 2 relatively high, and the ammonia adsorption operation means M2 is provided to provide the ammonia adsorption part 3 This is especially true when the temperature can be controlled relatively low.

In the case of using a combination of ammonia adsorbing and desorbing materials based on 130 ° C. under standard atmospheric pressure, the first ammonia adsorbing and desorbing material A1 is composed of a halogenated Ba compound, a halogenated Ca compound, a halogenated Sr compound, and a halogenated Mn. Any one or more selected from compounds can be used, and the second ammonia adsorption / desorption material A2 can be one or more selected from a halogenated Co compound, a halogenated Mg compound, and a halogenated Ni compound.
Further, when the combination of the ammonia adsorbing / desorbing material is set at 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 above.

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

(2) The configuration of the mixed exhaust gas temperature control means for controlling the temperature of the mixed exhaust gas is an ammonia fuel that supplies ammonia fuel to the SOFC 101 according to the amount of ammonia fuel required for the amount of power generation required for the SOFC 101 A 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 in accordance with 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, the heat held by the high temperature side exhaust gas is received and hot water is supplied. A heat exchanger for cogeneration (an example of a heat exchanger for hot water generation) to be obtained, and in the latter system, as a means for lowering the exhaust gas temperature, a heat radiator (radiation heat exchanger) that radiates the heat held by the high-temperature side exhaust gas to the atmosphere In the SOFC system according to the present invention, the positions of the former hot water generating heat exchanger and the latter radiator in the system are substantially the same. It is preferable that the exchanger and the radiant heat exchanger be exchangeable.
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 that uses ammonia directly or indirectly as a fuel, it was possible to provide an SOFC system that can reduce the energy consumption required for the operation of the SOFC system as much as possible.

1 Ammonia storage and supply device 2 Ammonia desorption part (ammonia storage part)
3 Ammonia adsorption part 4 Ammonia outlet 5 Exhaust gas inlet 6 Treated exhaust gas outlet 7 Distribution chamber 9 Cooling fan (heat radiator)
DESCRIPTION OF SYMBOLS 10 Housing | casing 20 Outer cylinder 21 Heat transfer tube 50 Waste heat recovery circuit 50a Outward passage 51 Hot water storage tank 52 Cogeneration heat exchanger (Heat exchange 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 receiving medium introduction path 100 Solid oxide fuel cell system (SOFC system)
101 Solid oxide fuel cell (SOFC)
102 Exhaust gas path 102a Mixed exhaust gas path 102b High temperature side exhaust gas path 102c Low temperature side exhaust gas path 102d Merging section 500 Radiator (exhaust gas temperature lowering means)
A1 1st ammonia adsorption / desorption material A2 2nd ammonia adsorption / desorption material M1 Ammonia desorption operation means M2 Ammonia adsorption operation means Mm Mixed exhaust gas generation means R for desorption operation R Ammonia adsorption / desorption material storage chamber TIC Temperature control controller V1 Valve V2 3 Directional 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 section s Detector

Claims (13)

An ammonia storage part that stores an ammonia adsorption / desorption material that is maintained in an ammonia adsorption state in which ammonia is adsorbed at an ammonia adsorption temperature and desorbs ammonia adsorbed at an ammonia desorption temperature higher than the ammonia adsorption temperature;
A solid oxide fuel cell that accepts ammonia supplied from the ammonia storage unit as fuel; and
A solid oxide fuel cell system comprising an exhaust gas path through which exhaust gas discharged from the solid oxide fuel cell flows,
In the exhaust gas path, the temperature of the exhaust gas flowing through the exhaust gas path is lowered and led to a heat supply part that supplies heat to the ammonia storage part, and the ammonia storage part is accommodated in the ammonia storage part. A solid oxide fuel cell system comprising an ammonia desorption operation means having an ammonia desorption temperature of the material, and wherein the ammonia storage unit is an ammonia desorption unit. The ammonia desorption operation means comprises
Exhaust gas temperature lowering means for lowering the temperature of the exhaust gas;
A mixed exhaust gas adjusted to be equal to or higher than the ammonia desorption temperature by mixing the high temperature side exhaust gas before the temperature reduction by the exhaust gas temperature reduction means and the low temperature side exhaust gas after the temperature reduction by the exhaust gas temperature reduction means. Comprising a mixed exhaust gas generating means for desorption operation to generate,
The solid oxide fuel cell system according to claim 1, further comprising a mixed exhaust gas introduction path that guides the mixed exhaust gas generated by the desorption operation mixed exhaust gas generation means to the heat supply unit. The desorption operation mixed exhaust gas generation means includes a high temperature side exhaust gas path through which the high temperature side exhaust gas flows and a low temperature side exhaust gas path through which the low temperature side exhaust gas flows, and from the high temperature side exhaust gas path and the low temperature side exhaust gas path It has a merge part where the outflowing gas merges,
3. The solid oxide fuel cell system according to claim 2, wherein 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 side exhaust gas and the low temperature side exhaust gas joined at the junction. .   The solid oxide fuel cell system according to claim 2 or 3, wherein the exhaust gas temperature lowering means is a hot water generating heat exchanger that receives the heat of the high temperature side exhaust gas to obtain hot water.   5. The solid oxide fuel according to claim 1, wherein the ammonia adsorption / desorption material is a metal halide compound having an ammonia adsorption / desorption equilibrium temperature of 40 ° C. or higher and 130 ° C. or lower at standard atmospheric pressure. Battery system.   6. The solid according to claim 1, wherein the ammonia adsorption / desorption material is at least one selected from a halogenated Ba compound, a halogenated Ca compound, a halogenated Sr compound, and a halogenated Mn compound. Oxide fuel cell system.   The solid oxidation as described in any one of Claims 1-6 which provided the ammonia adsorption part in which the ammonia adsorption / desorption material which adsorb | sucks the ammonia contained in the waste gas after desorption operation | movement discharged | emitted from the said heat supply part was accommodated. Physical fuel cell system.   8. The solid oxide fuel cell system according to claim 7, further comprising 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.   The solid oxide fuel cell system according to claim 8, wherein the ammonia adsorption operation means is a radiator that radiates and cools heat held by the ammonia adsorption unit to the atmosphere. An ammonia adsorption part for adsorbing and removing ammonia contained in the desorbed exhaust gas discharged from the heat supply part is provided,
The ammonia adsorption / desorption equilibrium temperature at the standard atmospheric pressure in the ammonia adsorption section is higher than the ammonia adsorption / desorption equilibrium temperature at the standard atmospheric pressure of the ammonia adsorption / desorption material stored in the ammonia desorption section. 6. The solid oxide fuel cell system according to claim 5, which contains a metal compound.   11. The solid oxide fuel cell system according to claim 10, wherein the ammonia adsorption part contains at least one selected from a halogenated Co compound, a halogenated Mg compound, and a halogenated Ni compound.   4. The solid oxide fuel cell system according to claim 2, wherein the exhaust gas temperature lowering means is a radiator that obtains the low temperature side exhaust gas by radiating the heat of the high temperature side exhaust gas to the atmosphere. An ammonia adsorption / desorption material for accommodating an ammonia adsorption / desorption material that adsorbs ammonia contained in the exhaust gas after desorption operation exhausted from the heat supply unit is provided, and an ammonia adsorption / desorption material accommodated in the ammonia adsorption unit. An ammonia adsorption operation means for setting the temperature to be equal to or lower than the ammonia adsorption temperature of the material,
A radiator that lowers the heat held by the heat receiving side heat medium introduced into the heat exchanger for hot water generation by releasing it into 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 lowered in temperature by the radiator to the ammonia adsorption unit;
A heat exchanging part that cools the ammonia adsorbing part by the heat receiving side heat medium;
5. The solid oxide fuel cell system according to claim 4, further comprising a high temperature side heat receiving medium introduction path for returning the heat receiving side heat medium received by the heat exchanging section to a heat receiving side heat medium inlet of the hot water generating heat exchanger. .

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