JP6812192B2 - Power generation system - Google Patents

Description

The present invention relates to a power generation system including a fuel cell.

In recent years, it is provided with a fuel electrode (anode) in which an oxidation reaction for oxidizing fuel is performed, an air electrode (cathode) in which a reduction reaction for reducing oxygen is performed, and an electrolyte arranged between the fuel electrode and the air electrode. Fuel cells have been developed that generate electricity through the electrochemical reaction of fuel and oxygen. Fuel cells include solid polymer electrolyte fuel cells (PEFC), phosphoric acid fuel cells (PAFC), molten carbonate fuel cells (MCFC), and solid oxide fuel cells (SOFC), depending on the characteristics of the electrolyte. It is roughly divided into four types.

The air electrode off gas discharged from the air electrode of the fuel cell contains nitrogen and oxygen. Therefore, as a technology for effectively utilizing the air electrode off gas, when the SOFC is stopped, the air electrode off gas is cooled and boosted, and further, only the nitrogen gas is separated and supplied to the fuel cell to cool the SOFC. A technique has been developed (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2016-100157

However, in the technique of Patent Document 1, since the air electrode off gas is cooled, the thermal energy of the air electrode off gas is impaired. Therefore, there is a need for the development of a technique for efficiently using the air electrode off-gas.

In view of such a problem, an object of the present invention is to provide a power generation system capable of efficiently utilizing the air electrode off gas discharged from the air electrode of a fuel cell.

In order to solve the above problems, the power generation system of the present invention comprises a fuel cell composed of one or both of a solid oxide fuel cell and a molten carbonate fuel cell, and a gas containing at least oxygen. A compressor that boosts the pressure and supplies it to the air electrode of the fuel cell and an oxygen adsorbent that adsorbs oxygen in a temperature environment higher than normal temperature are housed inside, and the air electrode off gas discharged from the air electrode of the fuel cell is discharged. A separation device having an adsorption tower to be supplied and separating the air electrode off gas into oxygen-enriched gas and nitrogen-enriched gas, and a fuel electrode off gas discharged from the fuel electrode of the fuel cell are separated by the separation device. It includes an off-gas combustor that burns with the separated oxygen-enriched gas, and a condenser that cools the combustion exhaust gas generated in the off-gas combustor and condenses water .

In order to solve the above problems, another power generation system of the present invention includes a fuel cell configured to include one or both of a solid oxide type fuel cell and a molten carbonate type fuel cell, and at least oxygen. A compressor that boosts gas and supplies it to the air electrode of the fuel cell and an oxygen adsorbent that adsorbs oxygen in a temperature environment higher than normal temperature are housed inside, and the air electrode discharged from the air electrode of the fuel cell. A separation device having an adsorption tower to which off-gas is supplied and separating the air electrode off- gas into oxygen-enriched gas and nitrogen-enriched gas, and a fuel electrode off-gas discharged from the fuel electrode of the fuel cell are at least oxygenated. An off-gas combustor that burns with gas containing the above gas, and a combustion engine that rotates a rotating shaft with combustion exhaust gas generated by the off-gas combustor, and the compressor is coaxially connected to the rotating shaft of the combustion engine. by the rotation of the rotating shaft, to boost the gas containing oxygen, the nitrogen-enriched gas separated by said separating apparatus, Ru is supplied to the off gas combustor.

In order to solve the above problems, the other power generation system of the present invention includes a fuel cell configured to include one or both of a solid oxide fuel cell and a molten carbonate fuel cell, and at least oxygen. A compressor that boosts gas and supplies it to the air electrode of the fuel cell and an oxygen adsorbent that adsorbs oxygen in a temperature environment higher than normal temperature are housed inside, and the air electrode discharged from the air electrode of the fuel cell. It has an adsorption tower to which off-gas is supplied, and includes a separation device for separating the air electrode off-gas into an oxygen-enriched gas and a nitrogen-enriched gas, and the compressor is provided with the oxygen-rich separated by the separation device. it supplied to the air electrode of the fuel cell by boosting the gas containing gases.

In order to solve the above problems, another power generation system of the present invention includes a fuel cell configured to include one or both of a solid oxide type fuel cell and a molten carbonate type fuel cell, and at least oxygen. A compressor that boosts gas and supplies it to the air electrode of the fuel cell and an oxygen adsorbent that adsorbs oxygen in a temperature environment higher than normal temperature are housed inside, and the air electrode discharged from the air electrode of the fuel cell. A separation device having an adsorption tower to which off-gas is supplied and separating the air electrode off- gas into oxygen-enriched gas and nitrogen-enriched gas, and a fuel electrode off-gas discharged from the fuel electrode of the fuel cell are at least oxygenated. An off-gas combustor that burns with gas containing the above gas, and a combustion engine that rotates a rotating shaft with combustion exhaust gas generated by the off-gas combustor, and the compressor is coaxially connected to the rotating shaft of the combustion engine. , the rotation of the rotary shaft, boosts the gas containing the oxygen-enriched gas, supplied to the air electrode and the off-gas combustor of the fuel cell.

In order to solve the above problems, another power generation system of the present invention includes a fuel cell configured to include one or both of a solid oxide fuel cell and a molten carbonate fuel cell, and at least oxygen. A compressor that boosts gas and supplies it to the air electrode of the fuel cell, and an oxygen adsorbent that adsorbs oxygen in a temperature environment higher than normal temperature are housed inside, and the air electrode discharged from the air electrode of the fuel cell. A separation device having an adsorption tower to which off-gas is supplied and separating the air electrode off-gas into an oxygen-enriched gas and a nitrogen-enriched gas, the oxygen-enriched gas separated by the separation device, and coal. It is reacted, and a coal gasification furnace to produce a gasification gas containing at least hydrogen to the fuel electrode of the fuel cell, the gasification gas produced by the coal gasification furnace Ru is supplied.

In order to solve the above problems, another power generation system of the present invention includes a fuel cell configured to include one or both of a solid oxide type fuel cell and a molten carbonate type fuel cell, and at least oxygen. A compressor that boosts gas and supplies it to the air electrode of the fuel cell and an oxygen adsorbent that adsorbs oxygen in a temperature environment higher than normal temperature are housed inside, and the air electrode discharged from the air electrode of the fuel cell. It has an adsorption tower to which off-gas is supplied, and a separation device that separates the air electrode off-gas into oxygen-enriched gas and nitrogen-enriched gas, and at least oxygen-containing gas and coal are reacted to produce at least hydrogen. and coal gasification furnace to produce a gasification gas containing, by the nitrogen-enriched gas separated by said separating apparatus, a conveying unit for pneumatic conveying the coal stored in the storage unit to the coal gasification furnace, a with Ru.

Further, the separation device may include a decompression pump that depressurizes the inside of the adsorption tower to desorb oxygen adsorbed on the oxygen adsorbent from the oxygen adsorbent and discharge it from the adsorption tower.
Further, the separation device may be driven by the electric power output from the fuel cell.

According to the present invention, it is possible to efficiently utilize the air electrode off gas discharged from the air electrode of the fuel cell.

It is a figure explaining the power generation system which concerns on 1st Embodiment. It is a figure explaining the power generation system which concerns on the 2nd Embodiment. It is a figure explaining the power generation system which concerns on 3rd Embodiment. It is a figure explaining the power generation system which concerns on 4th Embodiment. It is a figure explaining the power generation system which concerns on 5th Embodiment.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The dimensions, materials, other specific numerical values, etc. shown in the embodiment are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are designated by the same reference numerals to omit duplicate description, and elements not directly related to the present invention are not shown. To do.

(First Embodiment: Power Generation System 100)
FIG. 1 is a diagram illustrating a power generation system 100 according to the first embodiment. As shown in FIG. 1, the power generation system 100 includes a desulfurization device 110, a reformer 112, a fuel cell 114, a separation device 116, an off-gas combustor 118, a combustion engine 120, a compressor 122, and a generator. It includes 124, a heat exchanger 126, a condenser 128, a carbon dioxide compressor 130, a carbon dioxide recovery unit 132, and an inverter 140. In FIG. 1, the flow of substances such as gas and water is indicated by solid arrows, and the flow of electric power is indicated by dashed arrows.

The desulfurization apparatus 110 removes sulfur from the raw material gas (for example, city gas) GG1. The desulfurization apparatus 110 is composed of, for example, a desulfurizer filled with an adsorbent that adsorbs sulfur. Since various existing techniques can be applied to the technique for removing sulfur from the raw material gas GG1, detailed description thereof will be omitted here.

The reformer 112 reforms the raw material gas GG2 from which the sulfur content has been removed by the desulfurization device 110 to generate the reformed gas KG (including hydrogen (H ₂ ) and carbon monoxide (CO)). In the present embodiment, the reformer 112 is provided with a catalyst for accelerating the steam reforming reaction of hydrocarbons, and when the reformer 112 is supplied with the raw material gas GG2 (hydrocarbon) and steam. The steam reforming reaction represented by the following reaction formulas (1) and (2) proceeds, and the hydrocarbon is reformed into hydrogen and carbon monoxide.
C _n H _m + nH ₂ O → nCO + (m / 2 + n) H ₂ … Reaction equation (1)
CO + H ₂ O → CO ₂ + H ₂ … Reaction equation (2)
In this way, the reformed gas KG generated by the reformer 112 is supplied to the fuel electrode of the fuel cell 114. An oxygen-containing gas SG (for example, air) containing at least oxygen (O ₂ ) is supplied to the air electrode of the fuel cell 114 from a compressor 122 described later.

The fuel cell 114 converts the reformed gas KG and the oxygen-containing gas SG into electric power and heat. In this embodiment, the fuel cell 114 is composed of a solid oxide fuel cell (SOFC). A part of the electric power generated by the fuel cell 114 is supplied to the decompression pump 152 and the carbon dioxide compressor 130 described later via the inverter 140 described later, and the other electric power is supplied to the electric power utilization facility. Further, the heat generated by the fuel cell 114 is supplied to the heat utilization facility.

The air electrode off-gas KOG (for example, about 600 ° C.) discharged from the air electrode of the fuel cell 114 is composed of oxygen and nitrogen (N ₂ ) (for example, oxygen concentration is about 16%) and is supplied to the separator 116. To. The fuel cell 114 of the fuel electrode off-gas discharged from the fuel electrode NOG (e.g., about 600 ° C.) is carbon dioxide _(CO 2), water _(H 2 O), carbon monoxide, composed of hydrogen, off-gas combustion It is supplied to the vessel 118.

The separation device 116 separates the air electrode off-gas KOG into an oxygen-enriched gas SFG (a gas containing more oxygen than air) and a nitrogen-enriched gas CFG (a gas containing more nitrogen than air). In the present embodiment, the separation device 116 is a separation device using the Pressure Swing Adsorption (PSA) method, and includes an adsorption tower 150 and a pressure reducing pump 152 (vacuum pump). The adsorption tower 150 contains an oxygen adsorbent (for example, a perovskite-type oxide) that adsorbs oxygen in a temperature environment higher than room temperature (for example, 250 ° C. to 900 ° C.). The pressure reducing pump 152 decompresses the inside of the adsorption tower 150 to desorb the oxygen adsorbed by the oxygen adsorbent from the oxygen adsorbent and discharge it from the adsorption tower 150. As for the separation device of the PSA method using an oxygen adsorbent that adsorbs oxygen in a temperature environment higher than normal temperature, various existing techniques such as the technique described in Japanese Patent No. 560306 can be applied. , Detailed description is omitted.

A part of the oxygen-enriched gas SFG separated by the separation device 116 is supplied to the off-gas combustor 118. In addition, other oxygen-enriched gas SFG is supplied to the oxygen utilization facility. The nitrogen-enriched gas CFG separated by the separation device 116 is supplied to the nitrogen utilization facility.

The off-gas combustor 118 burns the fuel electrode off-gas NOG discharged from the fuel electrode of the fuel cell 114 with the oxygen-enriched gas SFG separated by the separator 116.

The combustion engine 120 is composed of, for example, a gas turbine or a gas engine, and the rotation shaft is rotated by the combustion exhaust gas HG (carbon dioxide, water) generated by the off-gas combustor 118. The compressor 122 is coaxially connected to the rotating shaft of the combustion engine 120, and the oxygen-containing gas SG is boosted (compressed) by the rotation of the rotating shaft of the combustion engine 120. The generator 124 is coaxially connected to the rotating shaft of the compressor 122, and generates electricity by rotating the rotating shaft of the compressor 122 (rotation of the rotating shaft of the combustion engine 120).

The heat exchanger 126 exchanges heat between the combustion exhaust gas HG after rotating the combustion engine 120 and the oxygen-containing gas SG boosted by the compressor 122. By providing the heat exchanger 126, the temperature of the oxygen-containing gas SG is raised by the heat of the combustion exhaust gas HG, and the power generation efficiency of the fuel cell 114 can be improved.

Further, the compressor 122 supplies the high pressure (higher pressure than atmospheric pressure) oxygen-containing gas SG to the air electrode of the fuel cell 114, so that the power generation efficiency of the fuel cell 114 can be improved. For example, when the compressor 122 boosts the oxygen-containing gas SG to 0.2 MPa and supplies it to the air electrode of the fuel cell 114, the power generation efficiency of the fuel cell 114 can be improved by about 20%.

The condenser 128 further cools the (cooled) combustion exhaust gas HG (carbon dioxide, water) whose heat has been exchanged by the heat exchanger 126, and condenses the water. Thereby, the combustion exhaust gas HG can be separated into carbon dioxide NG and water DS (drain water). The carbon dioxide NG separated by the condenser 128 is boosted by the carbon dioxide compressor 130 and recovered by the carbon dioxide recovery unit 132 of a carbon capture and storage (CCS) system or the like. Further, the water DS separated by the condenser 128 is discharged to the outside.

The inverter 140 converts the electric power (direct current) output from the fuel cell 114 into an alternating current. The electric power converted into alternating current by the inverter 140 is supplied to the decompression pump 152 and the carbon dioxide compressor 130.

As described above, according to the power generation system 100 according to the present embodiment, the separation device 116 is provided with an oxygen adsorbent that adsorbs oxygen in a temperature environment higher than room temperature, so that the thermal energy of the air electrode off-gas KOG can be obtained. It can be used for oxygen separation as it is without damaging it. Therefore, oxygen (oxygen-enriched gas SFG) can be efficiently separated from the air electrode off-gas KOG.

Further, since the oxygen-containing gas SG boosted by the compressor 122 is supplied to the air electrode of the fuel cell 114, the air electrode off gas KOG is also higher than the atmospheric pressure. Therefore, the air electrode off-gas KOG can be supplied to the adsorption tower 150 without providing a separate compressor. It is also conceivable to provide a compressor between the fuel cell 114 and the adsorption tower 150. However, in this case, the power generation efficiency of the fuel cell 114 cannot be improved. On the other hand, like the power generation system 100, the fuel cell 114 is provided with the compressor 122 on the upstream side of the fuel cell 114, that is, the compressor 122 boosts the oxygen-containing gas SG and supplies it to the air electrode of the fuel cell 114. It is possible to improve the power generation efficiency of the fuel cell and supply the air electrode off-gas KOG to the adsorption tower 150.

Further, as described above, the fuel electrode off-gas NOG is composed of carbon dioxide, water, carbon monoxide, and hydrogen. Therefore, the off-gas combustor 118 can generate combustion exhaust gas HG (carbon dioxide, water) containing almost no nitrogen by burning the fuel electrode off-gas NOG with the oxygen-enriched gas SFG. Therefore, carbon dioxide NG can be easily separated only by the condenser 128 cooling the combustion exhaust gas HG. Therefore, it is possible to reduce the cost required for separating carbon dioxide NG.

Then, by recovering the carbon dioxide NG by the carbon dioxide compressor 130 and the carbon dioxide recovery unit 132, it is possible to avoid the situation where the carbon dioxide NG is discharged to the atmosphere. That is, the power generation system 100 can generate CO _2- free power.

Further, since the decompression pump 152 and the carbon dioxide compressor 130 are driven by the electric power output from the fuel cell 114, the electric power, heat, oxygen-enriched gas SFG, and nitrogen-enriched without consuming external electric power. Gas CFG can be produced.

(simulation)
When the power generation system 100 can generate 250 kW of electric power, the air electrode off-gas KOG has an oxygen concentration of 16%, a temperature of 600 ° C., a pressure of 0.2 MPa, and a flow rate of 1250 Nm ³ / h. The maximum amount of oxygen-enriched gas SFG that can be separated (manufactured) from the air electrode off-gas KOG by the separation device 116 is 100 m ³ / h, and the power intensity is 0.35 kWh per 1 m ^{3 of} oxygen. On the other hand, in the off-gas combustor 118, the oxygen required to completely oxidize the fuel electrode off-gas NOG is 12.6 m ³ / h. From the above, it was found that the separator 116 can produce a larger amount of oxygen-enriched gas SFG consumed by the off-gas combustor 118.

(Second embodiment: power generation system 200)
FIG. 2 is a diagram illustrating a power generation system 200 according to a second embodiment. As shown in FIG. 2, the power generation system 200 includes a desulfurization device 110, a reformer 112, a fuel cell 114, a separation device 116, an off-gas combustor 218, a combustion engine 120, a compressor 122, and a generator. It includes 124, a heat exchanger 126, and an inverter 140. In FIG. 2, the flow of substances such as gas and water is indicated by solid arrows, and the flow of electric power is indicated by dashed arrows. Further, the components substantially the same as those of the power generation system 100 described above are designated by the same reference numerals, and duplicate description will be omitted.

In the present embodiment, the off-gas combustor 218 is supplied with the fuel electrode off-gas NOG discharged from the fuel electrode of the fuel cell 114 and the oxygen-containing gas SG (for example, air), and the off-gas combustor 218 is the fuel electrode. The off-gas NOG is burned by the oxygen contained in the oxygen-containing gas SG.

Further, in the power generation system 200 of the present embodiment, the nitrogen-enriched gas CFG separated by the separation device 116 is supplied to the off-gas combustor 218. When the fuel is burned with air, when the combustion temperature becomes a predetermined temperature (for example, 1200 ° C.) or higher, the amount of NOx (nitrogen oxide) produced sharply increases (expanded Zeldovich mechanism). Therefore, a conventional system including a fuel cell 114, an off-gas combustor 218, a combustion engine 120, and a compressor 122 is provided with a dedicated device for producing nitrogen-enriched gas from air, and the produced nitrogen-enriched gas can be used. It was supplied to the off-gas combustor 218 to lower the combustion temperature. Therefore, the initial cost and the running cost of the dedicated device for producing the nitrogen-enriched gas are incurred.

On the other hand, in the power generation system 200 of the present embodiment, the nitrogen-enriched gas CFG separated by the separation device 116 is supplied to the off-gas combustor 218, so that the power generation system 200 does not have a dedicated device for producing the nitrogen-enriched gas CFG. , NOx generation can be reduced. That is, it is possible to reduce the generation of NOx at low cost, and it is possible to reduce the NOx in the combustion exhaust gas HG exhausted from the power generation system 200.

(Third embodiment: power generation system 300)
FIG. 3 is a diagram illustrating a power generation system 300 according to a third embodiment. As shown in FIG. 3, the power generation system 300 includes a desulfurization device 110, a reformer 112, a fuel cell 114, a separation device 116, an off-gas combustor 318, a combustion engine 120, a compressor 322, and a generator. It includes 124, a heat exchanger 126, and an inverter 140. In FIG. 3, the flow of substances such as gas and water is indicated by solid arrows, and the flow of electric power is indicated by dashed arrows. Further, the components substantially the same as those of the power generation system 100 described above are designated by the same reference numerals, and duplicate description will be omitted.

In the present embodiment, the compressor 322 boosts the mixture SG / SFG of the oxygen-containing gas SG and the oxygen-enriched gas SFG. Then, the boosted air-fuel mixture SG / SFG is supplied to the air electrode of the fuel cell 114 via the heat exchanger 126.

Further, in the present embodiment, the off-gas combustor 318 is supplied with the fuel electrode off-gas NOG discharged from the fuel electrode of the fuel cell 114 and the air-fuel mixture SG / SFG boosted by the compressor 322, and the off-gas combustor 318 is supplied. Combusts the fuel electrode off-gas NOG with oxygen contained in the air-fuel mixture SG / SFG.

By supplying the off-gas combustor 318 with the air-fuel mixture SG / SFG boosted by the compressor 322, the pressure difference between the fuel electrode off-gas NOG and the air-fuel mixture SG / SFG can be reduced. This makes it possible to efficiently burn the fuel electrode off-gas NOG in the off-gas combustor 318.

Further, when the oxygen-containing gas SG is air, the air-fuel mixture SG / SFG has a higher oxygen partial pressure than the oxygen-containing gas SG. Therefore, the performance of the fuel cell 114 can be improved by supplying the air-fuel mixture SG / SFG having a high oxygen partial pressure to the air electrode of the fuel cell 114.

(Fourth Embodiment: Power generation system 400)
FIG. 4 is a diagram illustrating a power generation system 400 according to a fourth embodiment. As shown in FIG. 4, the power generation system 400 is a so-called integrated coal gasification combined cycle system, and includes a stockyard 410, a fine powder carbonizer 412, a transport unit 414, a coal gasification furnace 416, and a fuel cell 114. , Separator 116, off-gas combustor 118, combustion engine 120, compressor 122, generator 124, heat exchanger 126, condenser 128, carbon dioxide compressor 130, and carbon dioxide recovery unit 132. , Inverter 140 is included. In FIG. 4, the flow of substances such as gas and water is indicated by solid arrows, and the flow of electric power is indicated by dashed arrows. Further, the components substantially the same as those of the power generation system 100 described above are designated by the same reference numerals, and duplicate description will be omitted.

The stockyard 410 stores coal ST. Coal ST stored in the stockyard 410 is introduced into the fine carbonization apparatus 412. The pulverized carbonization apparatus 412 (storage unit) pulverizes the coal ST to produce pulverized coal BT. The transport unit 414 transports the pulverized coal BT produced by the pulverized carbonization apparatus 412 to the coal gasifier 416 by air using an inert gas (for example, nitrogen-enriched gas).

The coal gasification furnace 416 reacts a gas containing at least oxygen with a pulverized coal BT to generate a gasification gas SGG containing at least hydrogen. In the present embodiment, the oxygen-enriched gas SFG separated by the separation device 116 is introduced into the coal gasification furnace 416. Therefore, the coal gasification furnace 416 reacts the oxygen-enriched gas SFG separated by the separation device 116 with the pulverized coal BT to generate the gasification gas SGG.

A conventional system equipped with a coal gasifier 416 is provided with a dedicated device for producing oxygen-enriched gas from air, and supplies the produced oxygen-enriched gas SFG to the coal gasifier 416. The efficiency of producing gasified gas SGG was improved. Therefore, the initial cost and the running cost of the dedicated device for producing the oxygen-enriched gas are incurred. In the conventional integrated coal gasification combined cycle system that supplies the oxygen-enriched gas SFG to the coal gasification furnace 416, the power of the dedicated device for producing the oxygen-enriched gas accounts for about 50% of the power of the entire system. There was a need to reduce the cost required to produce enriched gas.

Therefore, the power generation system 400 of the present embodiment does not have a dedicated device for producing the oxygen-enriched gas SFG by supplying the oxygen-enriched gas SFG separated by the separation device 116 to the coal gasification furnace 416. In both cases, it becomes possible to efficiently generate gasified gas SGG. That is, it is possible to improve the production efficiency of the gasification gas SGG at low cost. Therefore, the power generation efficiency of the entire power generation system 400 can be improved, and the CO ₂ emission intensity can be reduced.

In this way, the gasified gas SGG generated by the coal gasification furnace 416 is supplied to the fuel electrode of the fuel cell 114.

Further, the transport unit 414 of the present embodiment airflow transports the pulverized coal BT produced by the pulverized carbonization apparatus 412 to the coal gasifier 416 using the nitrogen-enriched gas CFG separated by the separating apparatus 116. As a result, the cost of the inert gas used by the transport unit 414 can be reduced. Further, as described above, the nitrogen-enriched gas CFG has a high temperature of about 600 ° C. Therefore, it is possible to reduce the cost required for heating the inert gas as compared with the prior art using the inert gas.

(simulation)
When the power generation system 400 generates 1350 kW of electric power, the amount of oxygen required in the coal gasifier 416 is 535 m ³ / h. The air electrode off-gas KOG generated in the power generation system 400 has an oxygen concentration of 16%, a temperature of 600 ° C., a pressure of 0.55 MPa, and a flow rate of 6250 Nm ³ / h. Therefore, the amount of oxygen (oxygen-enriched gas SFG) that can be produced by the separator 116 of the power generation system 400 is 500 m ³ / h. From the above, it was found that in the power generation system 400, most of the oxygen required in the coal gasification furnace 416 can be covered by the air electrode off-gas KOG, and a small-scale and highly efficient power generation system can be constructed.

(Fifth Embodiment: Power generation system 500)
FIG. 5 is a diagram illustrating a power generation system 500 according to a fifth embodiment. As shown in FIG. 5, the power generation system 500 includes a methane fermentation tank 510, a digestion gas compressor 512, a carbon dioxide separator 514, a reformer 516, a fuel cell 114, a separator 116, and off-gas combustion. It is composed of a vessel 118, a combustion engine 120, a compressor 122, a generator 124, a heat exchanger 126, a condenser 128, a carbon dioxide compressor 130, a carbon dioxide recovery unit 532, and an inverter 140. To. In FIG. 5, the flow of substances such as gas and water is indicated by solid arrows, and the flow of electric power is indicated by dashed arrows. Further, the components substantially the same as those of the power generation system 100 described above are designated by the same reference numerals, and duplicate description will be omitted.

The methane fermentation tank 510 anaerobically decomposes biomass into microorganisms to generate digestion gas SKG containing at least methane (CH ₄ ) and carbon dioxide. The digestion gas compressor 512 boosts the digestion gas SKG and supplies it to the carbon dioxide separation unit 514. The carbon dioxide separation unit 514 is configured to include, for example, a carbon dioxide separation membrane, and separates the digestion gas SKG into carbon dioxide NG and methane-enriched gas GG.

The reformer 516 reforms the methane-enriched gas GG to produce the reformed gas KG. Similar to the reformer 112, the reformer 516 is provided with a catalyst for promoting the steam reforming reaction of hydrocarbons, and the methane-enriched gas GG and steam are supplied to the reformer 516. Then, the steam reforming reaction represented by the above reaction formulas (1) and (2) proceeds, and methane is reformed into hydrogen and carbon monoxide.

The carbon dioxide recovery unit 532 recovers the carbon dioxide NG separated by the carbon dioxide separation unit 514 in addition to the carbon dioxide NG from which water has been removed by the condenser 128.

As described above, according to the power generation system 500 according to the present embodiment, the fuel cell 114 generates power using the biomass-derived digestion gas SKG, and the off-gas combustor 118, the condenser 128, and the carbon dioxide compressor. Carbon negative power generation can be performed by recovering carbon dioxide NG by 130 and the carbon dioxide recovery unit 532.

Although the preferred embodiment of the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such an embodiment. It is clear that a person skilled in the art can come up with various modifications or modifications within the scope of the claims, which naturally belong to the technical scope of the present invention. Understood.

For example, in the above-described embodiment, SOFC has been described as an example of the fuel cell 114. However, the type of fuel cell is not limited as long as it can discharge the air electrode off-gas KOG whose temperature is higher than normal temperature. For example, a molten carbonate fuel cell (MCFC) may be adopted as the fuel cell 114. Further, as the fuel cell 114, a fuel cell in which SOFC and MSCF are combined may be adopted.

Further, in the above embodiment, as the separation device 116, a separation device using the PSA method has been described as an example. However, the separation device 116 is an adsorption tower in which an oxygen adsorbent that adsorbs oxygen in a temperature environment higher than normal temperature is housed at least, and the air electrode off-gas KOG discharged from the air electrode of the fuel cell 114 is supplied. It suffices to have. For example, as the separation device 116, a separation device using the Temperature Swing Adsorption (TSA) method may be adopted.

Further, in the above embodiment, the configuration in which the compressor 122 supplies air as the oxygen-containing gas SG to the air electrode of the fuel cell 114 has been described as an example. However, the compressor 122 boosts the gas containing the oxygen-enriched gas SFG (for example, the mixture of air and the oxygen-enriched gas SFG) separated by the separation device 116 as the oxygen-containing gas SG of the fuel cell 114. It may be supplied to the air electrode. As a result, the power generation efficiency of the fuel cell 114 can be improved.

Further, in the above embodiment, the configuration in which the compressor 122 is driven by the rotation of the combustion engine 120 has been described as an example. However, the compressor 122 may be driven by electric power. In this case, the compressor 122 is driven by the electric power output from the fuel cell 114 (the electric power converted into an alternating current by the inverter 140), so that the oxygen-containing gas SG can be boosted while reducing the power consumption. ..

Further, in the fourth embodiment, the configuration in which the oxygen-enriched gas SFG is supplied to the coal gasification furnace 416 has been described as an example. However, air may be supplied to the coal gasifier 416 in addition to the oxygen-enriched gas SFG.

The present invention can be used in a power generation system including a fuel cell.

100, 200, 300, 400, 500 Power generation system 114 Fuel cell 116 Separator 118, 218, 318 Off-gas combustor 120 Combustion engine 122, 322 Compressor 128 Condenser 150 Adsorption tower 152 Decompression pump 412 Fine powder carbonization device (storage unit)
414 Transport unit 416 Coal gasifier 514 Carbon dioxide separation unit 516 Reformer

Claims (8)

A fuel cell composed of one or both of a solid oxide fuel cell and a molten carbonate fuel cell, and
A compressor that boosts at least oxygen-containing gas and supplies it to the air electrode of the fuel cell.
It has an adsorption tower in which an oxygen adsorbent that adsorbs oxygen in a temperature environment higher than normal temperature is housed and the air electrode off gas discharged from the air electrode of the fuel cell is supplied, and the air electrode off gas is oxygenated. A separator that separates the enriched gas and the nitrogen-enriched gas,
An off-gas combustor that burns the fuel electrode off-gas discharged from the fuel electrode of the fuel cell with the oxygen-enriched gas separated by the separator.
A condenser that cools the combustion exhaust gas generated in the off-gas combustor and condenses water,
Power generation system equipped with. A fuel cell composed of one or both of a solid oxide fuel cell and a molten carbonate fuel cell, and
A compressor that boosts at least oxygen-containing gas and supplies it to the air electrode of the fuel cell.
It has an adsorption tower in which an oxygen adsorbent that adsorbs oxygen in a temperature environment higher than normal temperature is housed and the air electrode off gas discharged from the air electrode of the fuel cell is supplied, and the air electrode off gas is oxygenated. A separator that separates the enriched gas and the nitrogen-enriched gas,
An off-gas combustor that burns the off-gas of the fuel electrode discharged from the fuel electrode of the fuel cell with a gas containing at least oxygen.
A combustion engine that rotates the rotating shaft with the combustion exhaust gas generated by the off-gas combustor,
With
The compressor is coaxially connected to the rotating shaft of the combustion engine, and the rotation of the rotating shaft boosts the oxygen-containing gas.
The nitrogen-enriched gas separated by the separation device is a power generation system supplied to the off-gas combustor. A fuel cell composed of one or both of a solid oxide fuel cell and a molten carbonate fuel cell, and
A compressor that boosts at least oxygen-containing gas and supplies it to the air electrode of the fuel cell.
It has an adsorption tower in which an oxygen adsorbent that adsorbs oxygen in a temperature environment higher than normal temperature is housed and the air electrode off gas discharged from the air electrode of the fuel cell is supplied, and the air electrode off gas is oxygenated. A separator that separates the enriched gas and the nitrogen-enriched gas,
With
The compressor is a power generation system that boosts a gas containing the oxygen-enriched gas separated by the separation device and supplies it to the air electrode of the fuel cell. A fuel cell composed of one or both of a solid oxide fuel cell and a molten carbonate fuel cell, and
A compressor that boosts at least oxygen-containing gas and supplies it to the air electrode of the fuel cell.
It has an adsorption tower in which an oxygen adsorbent that adsorbs oxygen in a temperature environment higher than normal temperature is housed and the air electrode off gas discharged from the air electrode of the fuel cell is supplied, and the air electrode off gas is oxygenated. A separator that separates the enriched gas and the nitrogen-enriched gas,
An off-gas combustor that burns the off-gas of the fuel electrode discharged from the fuel electrode of the fuel cell with a gas containing at least oxygen.
A combustion engine that rotates the rotating shaft with the combustion exhaust gas generated by the off-gas combustor,
With
The compressor is coaxially connected to the rotating shaft of the combustion engine, and the rotation of the rotating shaft pressurizes the gas containing the oxygen-enriched gas to the air electrode of the fuel cell and the off-gas combustor. Power generation system to supply. A fuel cell composed of one or both of a solid oxide fuel cell and a molten carbonate fuel cell, and
A compressor that boosts at least oxygen-containing gas and supplies it to the air electrode of the fuel cell.
It has an adsorption tower in which an oxygen adsorbent that adsorbs oxygen in a temperature environment higher than normal temperature is housed and the air electrode off gas discharged from the air electrode of the fuel cell is supplied, and the air electrode off gas is oxygenated. A separator that separates the enriched gas and the nitrogen-enriched gas,
A coal gasification furnace that reacts the oxygen-enriched gas separated by the separation device with coal to generate a gasification gas containing at least hydrogen.
With
A power generation system in which the gasified gas generated by the coal gasification furnace is supplied to the fuel electrode of the fuel cell. A fuel cell composed of one or both of a solid oxide fuel cell and a molten carbonate fuel cell, and
A compressor that boosts at least oxygen-containing gas and supplies it to the air electrode of the fuel cell.
It has an adsorption tower in which an oxygen adsorbent that adsorbs oxygen in a temperature environment higher than normal temperature is housed and the air electrode off gas discharged from the air electrode of the fuel cell is supplied, and the air electrode off gas is oxygenated. A separator that separates the enriched gas and the nitrogen-enriched gas,
A coal gasification furnace that reacts at least oxygen-containing gas with coal to produce at least hydrogen-containing gasification gas.
A transport unit that airflows the coal stored in the storage unit to the coal gasification furnace by the nitrogen-enriched gas separated by the separation device.
Power generation system equipped with. Any one of claims 1 to 6 , wherein the separation device includes a decompression pump that depressurizes the inside of the adsorption tower, desorbs oxygen adsorbed on the oxygen adsorbent from the oxygen adsorbent, and discharges the oxygen from the adsorption tower. The power generation system described in the section. The power generation system according to any one of claims 1 to 7 , wherein the separation device is driven by electric power output from the fuel cell.

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