JPS6238828B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a fuel cell that uses hydrogen gas produced by steam reforming of a raw material gas containing hydrocarbons as a fuel and pressurized air as an oxidizing agent. Concerning improvements to battery power generation equipment. More specifically, using an externally heated reformer, the overall thermal efficiency (ratio of generated electric power energy to the total calorific value of the hydrocarbon fuel used; hereinafter,
Used with the same meaning. This invention relates to fuel cell power generation equipment that improves the efficiency of fuel cell power generation equipment. Here, the external heating type reformer refers to a method in which the reaction heat of the reforming reaction is indirectly supplied from the outside through heat exchange using a heat source other than the raw material gas flow (generally high-temperature combustion gas). Hereinafter, in the present specification, when it is simply referred to as a "reformer", unless otherwise specified, it refers to the external heat type refrigerant. [Background of the Invention] Fuel cell power generation equipment is well known in the art, and generally includes a reformer that generates hydrogen by steam reforming of a raw material gas containing hydrocarbons, and a reformer that generates hydrogen by steam reforming of a raw material gas containing hydrocarbons. The fuel cell includes a fuel cell that uses hydrogen as a fuel and pressurized air as an oxidizing agent, and a pressurized air generator, and the electrolyte of the fuel cell is, for example, a phosphoric acid aqueous solution. is used. Further, as the raw material hydrocarbons, for example, natural gas, naphtha, petroleum gas, etc. are used. Therefore, in this specification, the term "hydrocarbons" is used as a general term including not only these hydrocarbons but also methanol and the like. In order to make fuel cell power generation equipment economically comparable to power generation equipment using other methods, it is important to thoroughly increase its overall thermal efficiency, and various methods for this purpose have been studied. There is. When a fuel cell uses hydrogen gas obtained by steam reforming of hydrocarbons as fuel, this fuel gas contains inert gases such as carbon dioxide and methane. In order to maintain the partial pressure of hydrogen at the required level, it is necessary to continuously discharge a portion of the fuel gas supplied to the cell to the outside of the cell. This emitted gas (hereinafter referred to as
This is called residual fuel gas. ) as fuel gas for steam reheating is generally adopted as a method of increasing the overall thermal efficiency of power generation equipment. The overall thermal efficiency of fuel cell power generation equipment largely depends on the efficiency of the fuel cell itself, that is, the ratio of the electrical output of the fuel cell to the effective energy of the hydrogen consumed by the fuel cell. The efficiency of a fuel cell increases as the operating temperature of the cell increases and as the partial pressure of hydrogen gas on the fuel electrode (hydrogen electrode) side increases. Therefore, the operating conditions of a fuel cell should be within the allowable range for its structure and equipment materials. It is selected for its high temperature and high pressure. For example, in a fuel cell that uses an aqueous phosphoric acid solution as an electrolyte, the operating conditions are 190
℃ or higher (mainly about 190 to 215 degrees Celsius) and 3.5 atm or higher (mainly about 3.5 to 8 atm) are used. As fuel cell structures and device materials improve, the upper limits of temperature and pressure tend to rise. When air is used as an oxidant in fuel cells, the air contains a large amount of inert nitrogen gas, so in order to maintain the oxygen gas partial pressure at the oxygen electrode at the required level, excessive It is necessary to supply an amount of pressurized air and to exhaust a portion. If the excess rate of pressurized air is increased, the average oxygen gas partial pressure at the oxygen electrode will increase and the efficiency of the battery will be improved. Since the required power increases, there is an optimum value for this excess rate of pressurized air. Air with diluted oxygen (hereinafter referred to as residual air) discharged from the oxygen electrode of a fuel cell has considerable pressure energy when the fuel cell is operated under pressure, and this pressure Recovering energy by means of a gas turbine to provide part of the compressor power for supplying pressurized air is a known method for improving the overall thermal efficiency of power generation equipment. On the other hand, the residual fuel gas discharged from the hydrogen electrode of the fuel cell is used as a fuel for the heat source of the re-former as mentioned above, but the pressure energy of the residual fuel gas is recovered, and the combustion In order to improve the recovery efficiency of the thermal energy contained in the waste gas, the combustion chamber of the refoamer is pressurized in the same way as a fuel cell, and power is recovered by supplying the combustion waste gas to the gas turbine together with the aforementioned residual air. The method for doing this is already well known. Although the overall thermal efficiency of fuel cell power generation equipment has been greatly improved by the methods described above, it is still not sufficient. [Object of the Invention] Therefore, an object of the present invention is to further improve the overall thermal efficiency of fuel cell power generation equipment. [Structure and operation of the invention] The method of the present invention that achieves the above object uses hydrogen obtained by steam reforming of hydrocarbons as a fuel and pressurized air as an oxidizing agent. As a heat source for steam reheating,
The residual fuel gas discharged from the hydrogen electrode of the fuel cell is
Using the combustion heat generated by burning at least a portion of the remaining air discharged from the oxygen electrode of the fuel cell as an oxygen source, and the combustion heat is given to the hydrocarbons via a partition, The combustion gas accompanied by combustion heat is characterized in that it is discharged separately without being mixed with the hydrogen-containing gas obtained by steam reforming. Note that in the present invention, pressurized air refers to pressurized air of 3.5 atmospheres or more, and the upper limit of the pressure is limited by the structure of the fuel cell etc. and the material of the device. Further, the fuel cell power generation equipment of the present invention that achieves the above object uses hydrogen obtained by steam reforming of hydrocarbons as a fuel, and uses the compressed air as an oxidizing agent. , the power generation equipment includes a refohmer having a reaction chamber that generates hydrogen-containing gas from a raw material gas consisting of hydrocarbons and steam, a pressurized air generator that compresses air to generate pressurized air, and the refohmer. and a fuel cell including a hydrogen electrode into which the hydrogen generated by the pressurized air generator is introduced, and an oxygen electrode into which the air generated by the pressurized air generator is introduced, and the fuel is discharged from the hydrogen electrode of the fuel cell. A combustion chamber is provided in which residual gas is combusted using at least a portion of the residual air discharged from the oxygen electrode of the fuel cell as an oxygen source, and the reaction chamber is defined as the combustion chamber, and the combustion chamber in the combustion chamber is The chamber uses heat as a heat source for steam reforming, and further includes a combustion gas exhaust port for discharging combustion gas accompanied by combustion heat, and a hydrogen-containing gas discharge port, which are separately provided in the reformer. Characterize. According to the present invention, part or all of the residual air is used as an oxygen source for combustion of residual fuel gas in the refoamer. This eliminates the need for any combustion air for the refomamer and saves the compressor power required to compress this air. This amount of power saved is sufficiently larger than the amount of reduction in recovered power due to the overall reduction in the amount of gas supplied to the gas turbine, so it increases the overall thermal efficiency of the power generation equipment. Furthermore, in recent years, from the viewpoint of preventing air pollution, there has been an increasing demand for power generation equipment to reduce pollutants, particularly nitrogen oxides, in its exhaust gas. Fuel cells themselves generate electricity through electrochemical reactions, so they do not generate nitrogen oxides.
Since fuel residual gas is combusted in the refoamer, it is inevitable that a considerable amount of nitrogen oxides will be generated. In this regard, according to the present invention, since residual air with a low oxygen concentration is used as the oxygen source for combustion in the re-former, the combustion temperature is significantly lowered compared to the conventional method using air. Therefore, the generation of nitrogen oxides can be significantly reduced. Incidentally, from the viewpoint of effectively utilizing exhaust gas from fuel cells, a technique described in Japanese Patent Application Laid-Open No. 54-82636 (see Japanese Patent Publication No. 58-56231) is known. The method described in this publication consists of the following system. That is, the exhaust from the anode (hydrogen electrode) and the cathode (oxygen electrode) of the fuel cell are combusted in a burner, and the first part of the burner exhaust is supplied to a reheater, mixed with raw materials, and then steam reheated. A ming reaction takes place. The generated gas obtained by the internal heating type reformer is supplied to the anode, and the exhaust gas from the anode is supplied to the burner again and recycled. The second part of the burner exhaust, on the other hand, is exhausted. The system described in the above-mentioned publication uses an internal heating type re-former, unlike the present invention. Here, an internal heating type reformer is used to convert the reaction heat of reforming into the reaction heat generated by mixing oxygen-containing gas (generally air or pure oxygen gas) into the raw material gas and oxidizing a part of the raw material gas. This refers to a method of obtaining heat energy from the inherent thermal energy in the raw material gas flow itself, by mixing high-temperature gas into the raw material gas. The invention described in the publication is
As a heat source for the internal heating type reformer, combustion gas generated by combustion of residual fuel gas and residual air in the fuel cell is mixed into the raw material gas, and/or residual oxygen contained in the combustion gas is mixed into the raw material gas. It uses contamination. According to the invention, the moisture contained in the exhaust gas of the fuel cell can be recovered as a steam source for reforming, but the inert moisture contained in the oxygen source (in this case, the residual air of the fuel cell) can be recovered. Internal heating type reformers have a drawback in that gases (nitrogen, etc.) enter the raw material gas, lowering the hydrogen partial pressure of the reformer-generated gas and increasing the amount of gas to be processed. In particular, it is clear that using the remaining air of the fuel cell, which has a low oxygen concentration, as the oxygen source makes this drawback even more fatal. According to the present invention, by using an external heat type reformer, there is no such drawback at all, and furthermore, a highly efficient power generation facility has become possible due to the effective use of exhaust gas in the fuel cell. When using the residual air of a fuel cell as combustion air in a reflomer according to the method of the present invention, several difficulties may arise due to the low concentration of oxygen contained in the residual air. One of these is that the combustion gas is diluted with a large amount of nitrogen, which lowers the combustion temperature, making it difficult to obtain a sufficient amount of heat transfer with the conventional refoamer that uses a radiation heat transfer mechanism. There is no such thing. Another difficulty is that the low concentration of combustible gases and oxygen in the combustion chamber makes combustion unstable and prone to incomplete combustion and ignition failure. However, according to a preferred embodiment of the invention:
It is possible to provide a fuel cell power generation facility having a re-former that can obtain a sufficient amount of heat transfer even when the concentration of combustible gas and oxygen in the fuel gas and combustion air is low, and can operate stably. . That is, in this embodiment, a plurality of cylindrical reaction tubes with closed ends are arranged in a dense arrangement within the re-former container. A cylindrical reaction tube inner tube is further inserted inside each reaction tube, and a reaction chamber having an annular cross section defined by this reaction tube and the reaction tube inner tube is filled with a steam reforming catalyst. has been done. Furthermore, the inner side of the reaction tube is a regeneration chamber through which the product gas generated by steam reforming passes, and the raw material gas introduced into the reaction chamber from the open end of the reaction tube passes through the catalyst layer. The resulting gas becomes a generated gas containing hydrogen gas and reaches the closed end of the reaction tube. This generated gas enters the regeneration chamber defined inside the reaction tube from the closed end of the reaction tube.
The generated gas is discharged from the outlet near the open end of the reaction tube. The reaction tube inner tube provides a path for the produced gas and at the same time serves as a heat recovery device from the produced gas to the reaction chamber, thereby recovering a large portion of the sensible heat contained in the produced gas and discharging it in the reaction chamber. The resulting steam is effectively utilized as heat for the rehoming reaction. In the present invention, in order to ensure a sufficient heat transfer effect from the produced gas to the reaction chamber, an appropriate device for improving the heat transfer coefficient can be included inside the reaction tube inner tube. A combustion chamber is located between the outside of the reaction tube and the rifoma container, and this combustion chamber contains a gas that promotes the oxidation reaction of combustible gases (hydrogen, methane, carbon monoxide) contained in the fuel gas. It is filled with oxidation catalyst particles for Specific examples of this catalyst include oxides of noble metals such as platinum and palladium, base metals such as nickel, cobalt, iron, vanadium, chromium, copper, zinc, manganese, and magnesium, and mixtures thereof. In addition to acting as a catalyst, the catalyst particles also play a role in promoting heat transfer from the combustion gas to the reaction tube through a combined mechanism of radiation, convection, and heat transfer. The residual fuel gas as a fuel gas and the residual air as a source of oxygen for combustion are
The combustion waste gas is supplied into the combustion chamber from the closed end of the reaction tube, passes through the catalyst layer and is combusted, and the combustion waste gas is discharged from the side closer to the open end of the reaction tube to the outside of the reformer. Heat the reaction tube to the temperature required for the steam reheating reaction (750
℃ or higher), the gas temperature inside the combustion chamber must reach a maximum of about 1000℃, and in order to meet this condition, the residual fuel gas and residual air must be It is desirable that it is sufficiently preheated. Note that it is not necessarily a requirement that the combustion chamber of the present invention be provided in contact with the reaction tube of the rifoma.
For example, it may be provided in a space on the generated gas outlet side of the reaction tube or outside the reformer. in this case,
Combustion gas from the combustion chamber is introduced into a space in contact with the reaction tube. It is desirable that the space in contact with the reaction tube be filled with a packing material or the like for promoting heat transfer. [Examples] Features of the present invention and preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing a flow scheme in an embodiment of a conventional fuel cell power generation facility. FIG. 2 is a schematic diagram showing a flow scheme in an embodiment of the fuel cell power generation equipment according to the present invention. FIG. 1 and FIG. 2 are drawings for explaining the difference between the conventional power generation equipment and the power generation equipment according to the present invention, and therefore unnecessary equipment and flows for explanation are omitted. In the embodiment of the conventional power generation equipment shown in FIG. 1, raw material hydrocarbons 1 and reforming steam 2 are mixed to form raw material gas 3,
After being preheated by the raw material preheater 106, the reheater 1
01. The generated gas 4 containing hydrogen from the reformer 101 is cooled by an air preheater 107 and a fuel residual gas preheater 108, and then supplied to a shift converter 105. The shift converter 105 converts carbon monoxide in the generated gas into hydrogen and carbon dioxide gas by a shift reaction. The converted product gas 6 is transferred to the hydrogen electrode 111 of the fuel cell 102.
is supplied to The residual fuel gas 7 discharged from the hydrogen electrode 111 is preheated by the residual fuel gas preheater 108, and then supplied to the reheater 101 as fuel.
On the other hand, the air 11 is pressurized to a required pressure by the compressor 104. A portion 13 of the pressurized air 12 is supplied to the oxygen electrode 112 of the fuel cell 102 . The remaining portion 15 of the pressurized air is preheated by the air preheater 107 and then transferred to the reheater 10.
1 as combustion air (oxygen source). The residual fuel gas 7 is combusted in the reformer 101 by the combustion air 15, and after giving the raw material gas 3 the thermal energy necessary for steam reforming, it is discharged as reformer waste gas 8. After recovering a portion of the remaining thermal energy in the raw material preheater 106, the reheater waste gas 8 is supplied to the gas turbine 103 together with the remaining air 14 discharged from the fuel cell 102, and the pressure energy and thermal energy are used for power (driving). source) and then released as waste gas 10. The power recovered by the gas turbine 103 is used to drive the compressor 104. In order for the power recovered by the gas turbine 103 to match the power required to drive the compressor 104, the flow rate and temperature of the gas 9 supplied to the turbine must be maintained at a required level or higher. can be adjusted by increasing or decreasing the amount of residual fuel gas 7 discharged from the fuel cell 102. If the amount of fuel residual gas is increased while keeping the amount of raw material hydrocarbon 1 constant, the amount of hydrogen that can be consumed by the fuel cell 102 will naturally decrease, and the electrical output will decrease.
Therefore, if the driving power of the compressor 104 increases, there is a relationship in which the overall thermal efficiency of the entire power generation facility decreases. In the embodiment of the power generation installation according to the invention shown in FIG.
Used as combustion air (oxygen source) for 01. The remaining portion 17 of the residual air 14 is bypassed through the re-former 101 and directly supplied to the gas turbine 103.
supplied to In this embodiment, the compressor 10
All of the air 12 pressurized by 4 is supplied to the fuel cell 102 . Therefore, in the power generation equipment according to the present invention, the amount of air pressurized by the compressor 104 is smaller than that of conventional power generation equipment by an amount equivalent to the amount of combustion air 15 in the refoamer 101, and It also requires less power for driving. [Experimental example] In a fuel cell power generation facility with an output of 30 MW that uses methane as a raw material, a comparison was made using an experimental plant between the conventional facility shown in Figure 1 and the facility according to the present invention shown in Figure 2. It was confirmed that the method of the equipment according to the present invention has a higher overall thermal efficiency by about 0.7% than the conventional equipment. [Refohmer Embodiment] FIG. 3 is an illustrative partial vertical cross-sectional view showing a specific example of the refohmer used in the fuel cell power generation equipment according to the present invention. In this embodiment, the refohmer 200 includes a plurality of reaction tubes 202 that are densely packed within a refohmer container 201 . Each of the reaction tubes 202 has a cylindrical shape that extends vertically and has a closed upper end. Each reaction tube 202 includes a reaction tube inner tube 203, and a reaction chamber 204 is formed between the reaction tube 202 and the reaction tube inner tube 203. is defined. The reaction chamber 204 is filled with steam reforming catalyst particles 205 supported on a screen 221 located at the inlet 206 of the reaction chamber 204 . The reaction tube inner tube 203 defines therein a regeneration chamber 208 through which the product gas passes, and this regeneration chamber 208 has an inlet 209 near the reaction chamber outlet 207 and an outlet 210 near the reaction chamber inlet 206. They are respectively included in the generated gas manifold 234. A raw material gas 3 containing hydrocarbons 1 and steam 2 is introduced into the reformer 200 by a raw gas inlet nozzle 231, and is introduced into the raw material gas manifold 2.
32 and is supplied to each reaction chamber 204. When the raw material gas 3 enters the reaction chamber 204, it immediately starts a steam reforming reaction, and by the time it reaches the reaction chamber outlet 207, it is converted into a product gas containing hydrogen, carbon monoxide, carbon dioxide, steam, and a small amount of residual methane. do. The regeneration chamber 208 transfers the generated gas from the reaction chamber outlet 210 to the generated gas manifold 23.
At the same time, it serves as a means for recovering thermal energy from relatively high temperature generated gas and supplying reaction heat for the steam reforming reaction. In order to effectively achieve the purpose of the present invention, it is necessary to sufficiently recover thermal energy from the produced gas, and for this purpose, the heat transfer between the produced gas and the reaction tube inner tube 203 is sufficiently increased. It is important to design it so that it can be removed. Suitable devices may be included within the regeneration chamber 208 as a means to improve the heat transfer coefficient. As this device, for example, as in this embodiment, a plug 211 for narrowing the passage cross-sectional area and increasing the gas flow velocity, a buffling device for increasing the turbulence of the gas flow, or a packing material (for example, alumina balls) can be used. can. A rifoma container 201 is placed outside the reaction tube 202.
A combustion chamber 212 is defined between the two. The inside of the combustion chamber 212 is almost filled with oxidation catalyst particles 213, and the catalyst particles 213 are supported by a screen 222 arranged at the combustion chamber outlet 214 near the inlet side of the reaction chamber 204. The fuel residual gas 7 as the re-boomer fuel is supplied to the re-boomer 200 from the fuel inlet nozzle 237 and then to the combustion chamber 212 by the fuel nozzle 241 provided in the fuel manifold 238 .
On the other hand, the remaining air 16 as a source of oxygen for fuel is supplied to the reformer 200 from an air inlet nozzle 239 and then to the combustion chamber 212 by an air nozzle 242 provided in an air manifold 240. In order to effectively achieve the object of the present invention, the catalyst particles 213 filled in the combustion chamber 212 promote the oxidation reaction of the combustible components contained in the residual fuel gas 7, and also It is important to provide an effect that aids heat transfer. In this example, a platinum catalyst using alumina balls as a carrier was used. [Experiment example] The re-former in this example is a reaction tube 202.
The length of the reaction tube 202 is 1800 mm, the outer diameter of the reaction tube 202 is 200 mm,
The outer diameter of the reaction tube inner tube 203 was 150 mm, and the reaction tubes 202 were arranged in a staggered manner with a center-to-center distance of 250 mm. The raw material gas 3 obtained by using methane as the raw material hydrocarbons 1 and mixing it with steam 2 whose volume ratio is 4 times is preheated to about 460°C by the raw material gas preheater 106, and then passed through the reaction tube 2021. True accuracy approx. 2.9
It was supplied to the rifoma 101 at a rate of Kg/mol/h. Approximately 90% of the methane was decomposed in the rifoma, yielding product gas 4 containing approximately 48% hydrogen and approximately 6% carbon monoxide. Generated gas 4 is reformer 1
At the 01 outlet, the temperature was about 550°C and the pressure was about 4.5 atmospheres. The generated gas 4 was cooled to about 390° C. by the air preheater 107 and the fuel residual gas preheater 108, and then supplied to the shift converter 105. The generated gas 6, in which most of the carbon monoxide is converted into hydrogen and carbon dioxide by the shift converter 105, is transferred to the fuel cell 1 after excess water is removed.
02 was supplied to the hydrogen electrode 111. fuel cell 10
In 2, about 86% of the hydrogen was used for power generation. The residual fuel gas 7 discharged from the hydrogen electrode 111 contained about 30% hydrogen, about 8% methane, and less than 1% carbon monoxide as combustible components. After the residual fuel gas 7 is preheated to approximately 520°C by the residual fuel gas preheater 108, the residual fuel gas 7 is heated to approximately 520°C.
1 was supplied as fuel. On the other hand, the air 11 that is the oxygen source is pressurized to about 3.5 atmospheres by the compressor 104, and the entire amount is transferred to the oxygen electrode 11 of the fuel cell 102.
2 supplied. The amount of air supplied to the oxygen electrode is approximately 45% in excess of the theoretically required amount, and the remaining air 14 is approximately
It contained 7.5% oxygen. Approximately 80% of the residual air 14 discharged from the oxygen electrode 112 is the residual air 16 for combustion.
After being preheated to approximately 420°C, the remaining approximately 20
% residual air was taken as residual air bypass 17. The refoamer waste gas 8 discharged from the refoamer is approx.
The temperature was 520°C and the pressure was about 3.3 atmospheres. After the heat of the reformer waste gas 8 is recovered by the raw material gas preheater 106 and cooled to approximately 350° C., it joins the residual air bypass 17, and the driving power for the compressor 104 is recovered by the turbine 103. After that, it was ejected. The overall thermal efficiency of the power generation equipment of this example was 38.4%. [Application of the Invention] Although the present invention has been described in detail with reference to its preferred embodiments, the present invention is not limited to such embodiments, and various modifications and omissions can be made within the scope of the present invention. This will be clear to those skilled in the art. For example, in the present invention, it is most preferable from the viewpoint of improving overall thermal efficiency that the oxygen source used for combustion in the rifomar is essentially 100% residual air exhausted from the oxygen electrode of the fuel cell. A portion of the pressurized air originating from the air generator may be used directly as part of the oxygen source. Note that the above-mentioned refurmer used in the fuel cell power generation equipment of the present invention can also be used for other purposes as an endothermic reaction device. [Effects of the invention] (1) How to use residual air In a fuel cell power generation plant, used air (residual air) discharged from the air electrode of a fuel cell is used to generate hydrogen gas, which is the fuel for the fuel cell. There are two broad categories of techniques used in re-o-o-ma. One is the present invention, and in this method, as described above, residual air is introduced into the combustion chamber of an externally heated refoamer and used as an oxygen source for combustion, and then is converted into combustion gas ( (separately from the generated hydrogen gas). Therefore, this method can be called an externally heated residual air utilization method. The other method is disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 54-82636. In this method, as mentioned above, after the residual air is used for combustion in the burner, a part of the generated combustion gas is By mixing it with the raw material gas of the internal combustion reformer, it can be used as a heat source for the reforming reaction or an oxygen source for the partial oxidation reaction, and the water produced by the battery contained in the remaining air can be used to generate water vapor for the reforming reaction. will be supplied together. Therefore, this comparison method can be called an internal heating residual air utilization method. (2) Effects of residual air utilization method The effects of residual air utilization in the above two methods are compared by using a case where residual air is not used, that is, fresh air is used, and an example (calculation example). The quantitative results are as follows. That is, Fig. 4 to Fig. 7 are flow schemes showing data of each example (calculation example) of the present invention or a comparative example, and Fig. 4 shows an external heating method using fresh air;
Fig. 5 shows an external heating type residual air utilization method of the present invention, Fig. 6 shows an internal heating type residual air utilization method, and Fig. 7 shows an internal heating type residual air utilization method. The comparison results of the fuel cell power generation plant reforming systems shown in FIGS. 4 to 7 are shown in Table 1 below.

[Table] As shown in Table 1, the two methods, the external heating method and the internal heating method, are significantly different in their effects. That is, in the external heating residual air utilization method according to the present invention, by utilizing residual air, the thermal efficiency of the plant is approximately higher than when fresh air is used.
This is an increase of 1.5%. On the other hand, the efficiency of the comparative internal heating residual air utilization method is on the contrary.
This is because in the present invention, the amount of air used, that is, the required power of the air compressor, is reduced by utilizing the remaining air, thereby improving the plant thermal efficiency, whereas in the comparative technology, the Although the amount of hydrogen used is reduced, a large amount of nitrogen from the remaining air mixes into the hydrogen gas, which lowers the hydrogen concentration at the fuel electrode of the fuel cell and reduces the conversion efficiency (cell voltage) in the battery. This is thought to be due to In addition, in the comparative internal heating residual air utilization method, a large amount of nitrogen circulates within the system through the exhaust gas of the fuel electrode, so the flow rate of the generated hydrogen gas line is significantly increased (approximately three times in the example). This results in an increase in the size of the device. On the other hand, the external heating residual air utilization method according to the present invention does not have such drawbacks. In addition, in the comparative internal heating residual air utilization method, the water produced by the battery is used in the re-heater.
While the amount of water vapor consumed in a re-former can be greatly reduced (it is not required at all in the embodiment), there is no effect of reducing water vapor in the externally heated residual air utilization method of the present invention. As mentioned above, although both methods utilize residual air, their effects can be said to be completely different. (3) Meaning of Improving Power Plant Thermal Efficiency The greatest effect of the external heating residual air utilization method according to the present invention is improvement in plant thermal efficiency. Improving thermal efficiency is the most important issue in power plants, and efforts toward this goal have been accumulated for many years. As a result, the efficiency of thermal power plants, which was around 30% at the beginning of the 1950s, has decreased.
In 1980, it had improved to about 41% (Thermal and Nuclear Power Generation Technology Association, published October 15, 1980,
(Refer to “Thermal Power Generation Essentials,” 3rd edition, page 318). However, even today, the heavy solubility of efficiency improvement is not decreasing, but is actually increasing due to the rise in energy costs since the oil crisis. For example, if we look at the various developments made by manufacturers to increase the efficiency of power generation turbines for reference, we find that they are not neglecting their efforts to improve turbine efficiency, even if it is an improvement of 0.1% (turbine efficiency 0.1%). % increases in plant thermal efficiency by only about 0.04%), and from this, the efficiency improvement in the external heating residual air utilization method according to the present invention (in the example, the plant thermal efficiency increases by about 0.04%). 1.5%) is of great significance. Note that a technology for introducing residual air into the re-former using a non-pressurized system is known from Japanese Patent Publication No. 1382/1982, but this technology is used to recover water in the residual air and in the re-former combustion exhaust gas. The purpose is to perform these functions at the same time, and it does not have any effect on overall thermal efficiency.

[Brief explanation of the drawing]

FIG. 1 is an outline diagram showing a flow scheme in an embodiment of a conventional fuel cell power generation equipment, FIG. 2 is an outline diagram showing a flow scheme in an embodiment of a fuel cell power generation equipment according to the present invention, and FIG. 3 is an outline diagram showing a flow scheme in an embodiment of a fuel cell power generation equipment according to the present invention. Illustrative partial vertical cross-sectional views showing examples of a re-former used in fuel cell power generation equipment, and FIGS. 4 to 7 are flow schemes showing data of each example (calculation example) of the present invention or a comparative example. , Figure 4 shows how to use fresh air with an external heating type, Figure 5 shows how to use residual air with an external heating type of the present invention, Figure 6 shows how to use new air with an internal heating type, and Figure 7 shows how to use residual air with an internal heating type. Showing how to use air. 1... Raw material hydrocarbons, 2... Steam, 3...
... Raw material gas, 4... Produced gas, 5... Produced gas,
6... Converted product gas, 7... Fuel residual gas,
8... Reformer waste gas, 9... Turbine supply gas, 10... Waste gas, 11... Air, 12... Pressurized air, 13... Air for combustion battery, 14... Residual air, 15... Combustion Air for use, 16... Residual air for combustion, 17... Residual air bypass, 101... Refomar, 102... Fuel cell, 103... Turbine, 104... Compressor, 105... Shift converter, 106... Raw material Gas preheater, 107... Air preheater, 108... Fuel residual gas preheater, 111
...Hydrogen electrode, 112...Oxygen electrode, 200...Reformer, 201...Reformer container, 202...
Reaction tube, 203...Reaction tube inner tube, 204...Reaction chamber, 205...Reforming catalyst particles, 206...
...Reaction chamber inlet, 207...Reaction chamber outlet, 208...
... Regeneration chamber, 209 ... Regeneration chamber inlet, 210 ... Regeneration chamber outlet, 211 ... Plug, 212 ... Combustion chamber, 213 ... Oxidation catalyst particles, 214 ... Combustion chamber outlet, 221 ... Screen, 222 ... ... Scree, 231 ... Raw material gas inlet nozzle, 232 ...
Raw material gas manifold, 233... Produced gas outlet nozzle, 234... Produced gas manifold, 23
5... Fuel gas outlet nozzle, 236... Combustion gas manifold, 237... Fuel gas inlet nozzle,
238... Fuel gas manifold, 239... Air inlet nozzle, 240... Air manifold, 2
41...Fuel nozzle, 242...Air nozzle.

Claims (1)

[Claims] 1. A reformer for steam reforming in a fuel cell power generation facility that uses hydrogen obtained by steam reforming of hydrocarbons as a fuel and pressurized air as an oxidizing agent. As a heat source, combustion heat generated by burning residual fuel gas discharged from a hydrogen electrode of a fuel cell and at least a portion of residual air discharged from an oxygen electrode of the fuel cell is used as an oxygen source, The combustion heat is given to the hydrocarbons through the partition wall, and the combustion gas accompanied by the combustion heat is discharged separately without being mixed with the hydrogen-containing gas obtained by steam reforming. A method for effectively utilizing exhaust gas in fuel cell power generation equipment, characterized by: 2. Compression of pressurized air, which is the residual air discharged from the oxygen electrode of the fuel cell and is used as an oxygen source in the combustion chamber of the rifomar, is supplied as an oxidizing agent to the oxygen electrode of the fuel cell. Characterized by being used as energy for pressurization,
A method for effectively utilizing exhaust gas in a fuel cell power generation facility according to claim 1. 3. The exhaust gas in the fuel cell power generation equipment according to claim 1 or 2, characterized in that all of the oxygen source used for combustion in the re-former is residual air discharged from the oxygen electrode of the fuel cell. Effective usage. 4 In fuel cell power generation equipment that uses hydrogen obtained by steam reforming of hydrocarbons as a fuel and pressurized air as an oxidizer, this power generation equipment converts raw material gas consisting of hydrocarbons and steam into A refoamer having a reaction chamber that generates a hydrogen-containing gas, a pressurized air generator that compresses air and generates pressurized air, a hydrogen electrode that introduces hydrogen generated in the refoamer, and the pressurized air. and a fuel cell including an oxygen electrode into which air generated by the generator is introduced, and the remaining fuel gas discharged from the hydrogen electrode of the fuel cell is collected from the residual air discharged from the oxygen electrode of the fuel cell. A combustion chamber is provided in which at least a portion of the steam is burned as an oxygen source, and the reaction chamber is a chamber that is defined from the combustion chamber and uses combustion heat in the combustion chamber as a heat source for steam reforming. Further, a fuel cell power generation facility capable of effectively utilizing exhaust gas, characterized in that a combustion gas outlet for discharging combustion gas accompanied by combustion heat and a hydrogen-containing gas outlet are separately provided in the refoamer. 5. The fuel cell power generation equipment according to claim 4, wherein the combustion chamber includes a catalyst for promoting the oxygen reaction. 6. A reaction chamber in which the reformer is filled with a steam reforming catalyst and generates a product gas containing hydrogen from a raw material gas consisting of hydrocarbons and steam, and a sensible heat containing the product gas generated in this reaction chamber. a regeneration chamber that is in contact with the inside of the reaction chamber and leads out the generated gas led out from the reaction chamber in a direction opposite to the flow of gas in the reaction chamber for heat transfer to the reaction chamber; and an outside of the reaction chamber. a combustion chamber including a space in contact with the reaction chamber, the combustion chamber transmitting heat of the combustion gas led out in the flow direction opposite to the flow direction of the gas in the reaction chamber to the reaction chamber; A fuel inlet for introducing residual fuel gas discharged from the hydrogen electrode of the fuel cell into a combustion chamber portion located on the generated gas outlet side of the reaction chamber; and at least a fuel inlet for introducing residual fuel gas discharged from the oxygen electrode of the fuel cell. 6. The fuel cell power generation equipment according to claim 4, further comprising an oxygen source inlet for introducing a portion of the oxygen source. 7. The refoma includes a cylindrical reaction tube that extends vertically and has a closed upper end, and this reaction tube includes a cylindrical reaction tube inner tube with open upper and lower ends, and the reaction tube and the reaction tube inner tube The defined space having an annular cross section is a reaction chamber, and this reaction chamber is filled with steam reforming catalyst particles, and has a raw material gas inlet at the lower end and a product gas inlet at the upper end. The reaction tube inner tube defines a regeneration chamber inside thereof through which all of the generated gas passes, and this regeneration chamber has an upper end that contains the generated gas led out from the generated gas outlet of the reaction chamber. It has an inlet for introducing the gas and an outlet for the generated gas on the lower end side, and a plurality of the reaction tubes are densely arranged in the re-former container, and a wall is provided between the re-former container and each reaction tube. The defined space is a combustion chamber, and this combustion chamber has at its upper end a fuel inlet for introducing fuel residual gas discharged from the hydrogen electrode of the fuel cell, and a fuel inlet for introducing fuel residual gas discharged from the oxygen electrode of the fuel cell. and an oxygen source inlet for introducing at least a portion of the remaining air, and the combustion chamber has a combustion gas outlet at the lower end thereof, and the combustion chamber does not include a catalyst for promoting the oxidation reaction. and the heat required for the steam reforming reaction occurring in the reaction chamber is supplied through a combustion chamber containing the oxidation reaction catalyst and a regeneration chamber which is a passage for generated gas, respectively. The fuel cell power generation equipment described in item 4. 8 The remaining air exhausted from the oxygen electrode of the fuel cell is
Claims 4 and 5 are characterized in that they are configured to be used as an oxygen source in a combustion chamber of a rifomar and as a drive source for a pressurized air generator.
6. The fuel cell power generation equipment according to item 6 or 7. 9. Claim 4, characterized in that all of the oxygen source used for combustion in the re-former is residual air discharged from the oxygen electrode of the fuel cell,
The fuel cell power generation equipment according to item 5, 6, 7, or 8.