JP2000204965A - Gas turbine generation system using methane gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency while reducing the using quantity of methane gas that is the fuel by catalytically reacting methane gas with carbon dioxide in a catalytic reactor to generate carbon monoxide and hydrogen, combusting them in a gas turbine, and heating the catalytic reactor with the resulting combustion heat. SOLUTION: A catalytic reactor 6 performs the catalytic reaction of methane gas 11 with carbon dioxide 9a under the environment having the temperature of turbine exhaust gas 16b to generate a fuel gas 13 consisting of carbon monoxide and hydrogen. The fuel gas 13 is introduced into the combustor 5 of a gas turbine 1. Oxygen 15 is also compressed by a compressor 2 and introduced into the combustor 5. In the combustor 5, the fuel gas 13 and the compressed oxygen 15 are combusted to generate a combustion gas 16a consisting of high- temperature carbon dioxide and steam. This combustion gas 16a is introduced into an expander 3 to drive a generator 4, and power generation is performed. The combustion gas 16a after generation is recovered in the catalytic reactor 6 and reused for heating of the catalytic reactor 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine power generation system using methane gas, and more particularly, to a catalytic reaction utilizing exhaust heat of a gas turbine, instead of directly burning methane gas in a gas turbine to generate power. This is a gas turbine power generation system that reforms methane gas into CO and H ₂ and burns the CO and H ₂ in a gas turbine to generate power.

[0002]

2. Description of the Related Art Natural gas, especially methane gas (CH ₄ )
In a gas turbine using methane as a fuel, methane gas is directly combusted with air in the gas turbine to generate power, and CO ₂ , H ₂ O (water vapor), and N ₂ are discharged as turbine exhaust gas. Here, the turbine exhaust gas is subjected to heat recovery by an exhaust heat recovery device (for example, an exhaust heat boiler, a steam turbine, or the like).

[0003]

[Problems to be solved by the invention] However, 1 kg-m
ol, theoretically, 212,160 kc
al (about 891,072 kJ) can be obtained, but in the operation of the gas turbine according to the conventional method, the thermal efficiency of the cycle was only about 30 to 40%.

[0004] Therefore, from the viewpoints of improving power generation efficiency and reducing power generation costs, a power generation system (cycle) with higher efficiency and less fuel consumption is required.

Accordingly, an object of the present invention is to provide a gas turbine power generation system that solves the above-mentioned problems and is highly efficient and uses less methane gas as fuel.

[0006]

According to a first aspect of the present invention, there is provided a power generation system for a gas turbine using methane gas as a fuel, wherein the methane gas is brought into contact with carbon dioxide in a catalytic reactor. To generate carbon monoxide and hydrogen, burn the carbon monoxide and hydrogen in a gas turbine, and heat the catalytic reactor with heat generated by the combustion.

In a second aspect of the present invention, in a power generation system for a gas turbine using methane gas as a fuel, the methane gas is brought into contact with steam in a catalytic reactor to generate carbon monoxide and hydrogen. And hydrogen are burned in a gas turbine, and the heat generated by the combustion heats the catalytic reactor.

According to the above configuration, by burning carbon monoxide and hydrogen in the gas turbine, it is possible to obtain higher energy than burning methane gas directly in the gas turbine.

According to a third aspect of the present invention, the catalyst reactor is heated to about 600 ° C. using turbine exhaust gas, and a high-speed conversion catalyst is used as a catalyst for the catalyst reactor.
Or a gas turbine power generation system using methane gas according to claim 2.

According to the above configuration, the heat source of the turbine exhaust gas can be effectively used as it is, and the methane gas and the carbon dioxide (or water vapor) can be converted to a high speed comparable to the combustion speed by using the high speed conversion catalyst. Can be converted to carbon monoxide and hydrogen.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of a gas turbine power generation system using methane gas according to the present invention.

As shown in FIG. 1, the gas turbine power generation system of the present invention comprises a gas turbine 1 for performing combustion and power generation,
The catalyst reactor 6 provided in the recovery line 17 for the turbine exhaust gas 16b, the exhaust heat recovery unit 7 provided on the downstream side of the catalyst reactor 6 in the recovery line 17, and the exhaust heat recovery unit 7 in the recovery line 17 Condenser 8 provided on the downstream side
It is composed of

The catalyst reactor 6 converts methane gas (CH ₄ ) 11 and carbon dioxide (CO ₂ ) 9a using a high-speed conversion catalyst (not shown) under the condition of the temperature of the turbine exhaust gas 16b (about 600 ° C.). Catalytic reaction, carbon monoxide (CO)
And a fuel gas 13 comprising hydrogen (H ₂ ) and a methane gas introduction line 21.

Here, CO ₂ separated by the condenser 8
The condenser 8 and the catalytic reactor 6 are connected by a CO ₂ supply line 12 so as to supply a part 9 a of 9 to the catalytic reactor 6.

The gas turbine 1 includes a compressor 2 for compressing oxygen (O ₂ ) 15 and a fuel gas 1 together with compressed oxygen.
3 that includes a combustor 5 that performs combustion of the fuel cell 3, an expander 3 that is driven by a combustion gas 16a obtained by burning compressed oxygen and the fuel gas 13, and a generator 4 that is connected to the expander 3. is there.

Here, in order to introduce the fuel gas 13 generated in the catalytic reactor 6 into the combustor 5, the catalytic reactor 6 and the combustor 5
Are connected by a fuel gas introduction line 18. In order to circulate another part 9b of the CO ₂ 9 separated by the condenser 8 to the compressor 2 to prevent surging, the condenser 8 and the compressor 2 are connected by a CO ₂ circulation line 19.

Examples of the high-speed conversion catalyst include a solid catalyst used for reducing carbon dioxide with methane gas at a temperature of 600 ° C. For example, Ni (10 wt%) is a main component and is equivalent to １ ／ atom. Ce oxide and 1/30
A ceramic fiber nonwoven fabric (ceramic fiber) coated with a four-component catalyst obtained by combining Pt equivalent to atoms and Rh equivalent to 1/90 atoms with a fine particle layer of alumina
And a plurality of (for example, three) stages supported on the surface of the substrate.

The majority of the volume of the high-speed conversion catalyst is occupied by voids, the porosity of which is about 90%, and the void diameter is about 5 to 10 μm. These voids can reduce the diffusion resistance of the reaction gas (fuel gas 13), reduce blow-through, and maintain high contact efficiency with the catalyst even at high flow rates.

Further, the high-speed conversion catalyst may be formed in a honeycomb type and arranged in the catalyst reactor 6, whereby
It is possible to adapt to reaction conditions of a larger flow rate.

The gas turbine power generation system of the present invention shown in FIG. 1 is a co-generation system in which steam is generated by the exhaust heat recovery unit 7 provided in the recovery line 17, but it is a system only for power generation. In this case, it goes without saying that the exhaust heat recovery unit 7 is not required.

Next, the operation of the present invention will be described with reference to the accompanying drawings.

FIG. 3 shows a chemical reaction equation in the catalytic reactor 6 and the gas turbine 1 in the gas turbine power generation system using methane gas of the present invention.

As shown in FIGS. 1 and 3, in the catalytic reactor 6, the temperature environment of the turbine exhaust gas 16b (about 600
℃), 1 mol of methane gas 1
Catalytic reaction of 1 mol of carbon dioxide 9a with respect to 1
mol of carbon monoxide and hydrogen (fuel gas 13) are produced. According to this high-speed conversion catalyst, the gas hourly space velocity (SV) per catalyst real volume is 730,000 / h, and the contact time is 4.
Even under extremely short contact conditions of 9 m-sec, methane gas 1
The reaction between 1 and carbon dioxide 9a almost approaches the equilibrium conversion, and for example, under a temperature environment of 600 ° C., the space-time yield of hydrogen reaches 3,585 mol / l · h.

Since this catalytic reaction is an endothermic reaction of 483.4 kJ / mol, if such a large endothermic reaction proceeds at a high speed, there is a possibility that heat supply from the outside of the catalyst layer by the turbine exhaust gas 16b may not be enough. Therefore, in order to compensate for a large heat absorption, heat may be supplied from inside the catalyst layer by combining catalytic combustion of the methane gas 11 itself or catalytic combustion of ethane gas or propane gas, which is more flammable than methane gas. Thereby, the limit of the conversion rate due to the equilibrium of the reaction is exceeded, so that the catalyst reaction can be stably maintained even under a low temperature condition of about 300 to 400 ° C.

Next, the fuel gas 13 is introduced into the combustor 5 of the gas turbine 1 via the fuel gas introduction line 18. Further, the oxygen 15 is compressed using the compressor 2,
It is introduced into the combustor 5. Here, surplus hydrogen in the fuel gas 13 is appropriately collected as surplus H ₂ 14.

In the combustor 5, as shown in FIG. 3, the fuel gas 13 and the compressed oxygen are burned, and the high temperature (about 1300
~ 1500 ° C) carbon dioxide and water vapor (combustion gas 1
6a) is generated.

At this time, if 1 kg-mol of methane gas 11 is directly burned, only 212,160 kcal (about 891,072 kJ) of energy can be obtained, but 1 kg-mol of methane gas 11 and 1 kg-mol of carbon dioxide 9a are converted. 2 kg-mol of carbon monoxide and hydrogen produced by the catalytic reaction (fuel gas 1
When 3) is burned, the energy of 2 kg-mol of carbon monoxide (135,520 kcal (about 569,184 kJ)) and the energy of 2 kg-mol of hydrogen (135,480 kcal (about 569,016 kJ)) are combined to 271,000 kcal (about 1,138,200 kJ). ) Energy can be obtained. That is, it is possible to obtain about 1.28 times higher energy than directly burning the methane gas 11.

The combustion gas 16a is introduced into the expander 3 to drive the generator 4 to generate power. The gas temperature of the combustion gas 16a (turbine exhaust gas 16b) after power generation has dropped to about 600 ° C. due to expansion.
It is introduced into the catalyst reactor 6 through 7 and used for heating the catalyst reactor 6. Thereafter, the turbine exhaust gas 16b is introduced into the exhaust heat recovery unit 7 via the recovery line 17, and the exhaust heat is recovered.

Finally, the turbine exhaust gas 16b is introduced into the condenser 8 and cooled by the cooling water W, and water vapor is recovered as water (H ₂ O) 10 and carbon dioxide (CO ₂ ) 9
Is separated. Part 9a of the separated carbon dioxide 9 is CO
_{2 It is} supplied to the catalytic reactor 6 via the supply line 12 and used for catalytic reaction with the methane gas 14. Another part 9b of the carbon dioxide 9 is circulated to the compressor 2 via a CO ₂ circulation line 19 in order to prevent surging in the compressor 2 and adjust combustion temperature in the gas turbine 1. Further, the remaining carbon dioxide 9 is recovered as surplus CO ₂ 9c.

Here, the recovered excess CO ₂ 9c is converted to a temperature environment of 200 ° C. or higher (for example, between the catalyst reactor 36 and the exhaust heat recovery unit 7 in the recovery line 27) by using the excess H ₂ 14. ) To reduce (CO ₂ + 4H ₂ → CH ₄ +2)
H ₂ O + 177.6 kJ / mol), which generates methane gas and water vapor and generates heat at 400 to 450 ° C., so that heat recovery can be performed and methane gas is circulated to the catalyst reactor 6. Can be done.

According to the present invention, it is possible to obtain approximately 1.28 times the energy from the same amount of methane gas as compared with the conventional gas turbine power generation system using methane gas. And the fuel cost can be reduced.

Further, since the amount of methane gas 11 used can be suppressed, the amount of carbon dioxide 9 emitted is reduced as compared with a conventional gas turbine power generation system using methane gas.

Further, parts 9a and 9b of the carbon dioxide 9 generated by the gas turbine 1 can be reused and circulated to the gas turbine power generation system.

[0035] In the present invention, is used an oxygen 15 to combustion in the gas turbine 1, the air may be used, not to mention that case, CO ₂ circulation line 1
9 is not required, but a separator for separating carbon dioxide and nitrogen is required in the CO ₂ supply line 12 connecting the condenser 8 and the catalytic reactor 6.

Next, another embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 2 is a schematic diagram of a gas turbine power generation system using methane gas according to the present embodiment. The same members as those in FIG. 1 are denoted by the same reference numerals.

In the gas turbine power generation system using methane gas of the present invention, the methane gas 1
1 and carbon dioxide 9a.

On the other hand, in the gas turbine power generation system using methane gas according to the present embodiment, as shown in FIG. 2, the methane gas 11 and the steam 22 are catalytically reacted in the catalytic reactor 36. Gas turbine 1 for combustion and power generation, and recovery line 2 for turbine exhaust gas 26
7 and an exhaust heat recovery unit 7 provided on the recovery line 27 on the downstream side of the catalyst reactor 36.
And a condenser 8 provided downstream of the exhaust heat recovery unit 7 in the recovery line 27.

The catalytic reactor 36 uses a high-speed conversion catalyst (not shown) and a methane gas (CH ₄ ) 11 and steam (H ₂ ) under the temperature environment (about 600 ° C.) of the turbine exhaust gas 16.
O) 22 to produce a fuel gas 23 composed of carbon monoxide (CO) and hydrogen (H ₂ ), and has a methane gas introduction line 21 and a steam introduction line 24.

As a high-speed conversion catalyst, 400-500 ° C.
A solid catalyst used when steam reforming methane gas using water vapor in a temperature environment described above.

The majority of the volume of the high speed conversion catalyst is occupied by voids, the porosity of which is about 90%, and the void diameter is about 5 to 10 μm. These voids can reduce the diffusion resistance of the reaction gas (fuel gas 23), reduce blow-through, and maintain high contact efficiency with the catalyst even at high flow rates.

Furthermore, the high-speed conversion catalyst may be configured in a honeycomb type and arranged in the catalyst reactor 36, thereby making it possible to adapt to the reaction conditions of a larger flow rate.

The gas turbine 1 has the same configuration as the gas turbine 1 shown in FIG.

In the gas turbine power generation system of the present embodiment shown in FIG. 2, a co-generation system in which steam is generated by the exhaust heat recovery unit 7 provided in the recovery line 27 is used. Needless to say, in this case, the exhaust heat recovery unit 7 becomes unnecessary.

Next, the operation of the present embodiment will be described with reference to the accompanying drawings.

FIG. 4 shows a chemical reaction equation in the catalytic reactor 36 and the gas turbine 1 in the gas turbine power generation system using methane gas according to the present embodiment.

As shown in FIGS. 2 and 4, in the catalytic reactor 36, the temperature environment (about 60
(0 ° C.), 1 mol of methane gas 11 is reacted with 1 mol of water vapor (H ₂ O) 22 using a high-speed conversion catalyst to produce 1 mol of carbon monoxide and 3 mol of hydrogen (fuel gas 23). . Here, as the steam 22 used for the catalytic reaction, it is possible to use steam generated by an exhaust heat boiler (not shown) as one of the exhaust heat recovery units 7 or the like.

This catalytic reaction is an endothermic reaction of 205.8 kJ / mol. Although the endothermic amount is small as compared with the catalytic reaction of the present invention shown in FIG. 3, when such a large endothermic reaction proceeds at a high speed, the catalytic reaction proceeds. Turbine exhaust gas 26b from outside the bed
May not be able to keep up with the heat supply by
As in the present invention, methane gas 1
Heat may also be supplied from the inside of the catalyst layer by combining the catalytic combustion of 1 itself or the catalytic combustion of ethane gas or propane gas, which is more flammable than methane gas.

Next, the fuel gas 23 is introduced into the combustor 5 of the gas turbine 1 via the fuel gas introduction line 18. In this embodiment, air (Ai) is used instead of oxygen.
r) 25 is compressed using the compressor 2 and introduced into the combustor 5. Here, surplus hydrogen in the fuel gas 23 is appropriately collected as surplus H ₂ 14.

In the combustor 5, as shown in FIG. 4, 1 mol of carbon monoxide and 1 mol of hydrogen and the compressed air of the fuel gas 23 are burned to produce carbon dioxide, water vapor and nitrogen. . Further, of the fuel gas 23, 2 mol of hydrogen and compressed air are burned to generate steam and nitrogen. These high-temperature (about 1300 to 1500 ° C.) carbon dioxide, water vapor, and nitrogen are supplied to the expander 3 as the combustion gas 26a.

At this time, if 1 kg-mol of methane gas 11 is directly burned, only 212,160 kcal (about 891,072 kJ) of energy can be obtained, but 1 kg-mol of methane gas 11 and 1 kg-mol of water vapor 22 are used as a catalyst. When 1 kg-mol of carbon monoxide and 3 kg-mol of hydrogen (fuel gas 23) produced by the reaction are burned, the energy of 1 kg-mol of carbon monoxide is 67,760 kcal (about 284,592 kJ) and 3 kg-mol of Combined with the hydrogen energy of 203,220 kcal (about 853,524 kJ), energy of 270,980 kcal (about 1,138,116 kJ) can be obtained. That is, it is possible to obtain about 1.28 times higher energy than directly burning the methane gas 11.

The combustion gas 26a is introduced into the expander 3 to drive the generator 4 to generate power. The gas temperature of the combustion gas 26a (turbine exhaust gas 26b) after power generation has dropped to about 600 ° C. due to expansion.
7 and is introduced into the catalytic reactor 36 through the catalytic reactor 36
Used for heating. Then, the turbine exhaust gas 26b
Is introduced into the exhaust heat recovery unit 7 through the recovery line 27,
Waste heat is recovered.

The turbine exhaust gas 26b after the recovery of the exhaust heat is introduced into the condenser 8 and cooled by the cooling water W to recover the water vapor as water (H ₂ O) 10 and to remove carbon dioxide (CO ₂ ) and nitrogen ( The mixed gas 29 of N ₂ ) is separated. The separated mixed gas 29 is separated and recovered into nitrogen and carbon dioxide using the above-described separator or the like. The nitrogen recovered in the separator can be circulated to another device. Also, carbon dioxide, with excess H ₂ 14 200
° C (for example, between the catalyst reactor 36 and the exhaust heat recovery unit 7 in the recovery line 27).
O ₂ + 4H ₂ → CH ₄ + 2H ₂ O + 177.6 kJ / mol), which generates methane gas and water vapor and generates heat at 400 to 450 ° C., so that heat can be recovered and methane gas can be recovered. Can be circulated to the catalytic reactor.

In this embodiment, the same effects as those of the present invention can be obtained.
Since the air 25 can be used for the combustion of the fuel, the power generation cost can be further reduced.

[0056]

In summary, according to the present invention, instead of directly burning methane gas as a fuel, a catalytic reaction between methane gas and carbon dioxide or steam produces carbon monoxide and hydrogen, and this monoxide is produced. By using gas turbine fuel as a fuel gas consisting of carbon and hydrogen, the energy conversion efficiency of a gas turbine power generation system using methane gas is increased, and the excellent effect of using less methane gas as fuel is required. Demonstrate.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a gas turbine power generation system using methane gas of the present invention.

FIG. 2 is a schematic diagram of a gas turbine power generation system using methane gas according to another embodiment.

FIG. 3 is a chemical reaction equation in the catalytic reactor 6 and the gas turbine 1 in the gas turbine power generation system using methane gas of the present invention.

FIG. 4 is a chemical reaction formula in a catalytic reactor 36 and a gas turbine 1 in a gas turbine power generation system using methane gas according to another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas turbine 6,36 Catalytic reactor 9a Carbon dioxide 11 Methane gas 13,23 Fuel gas (carbon monoxide and hydrogen) 16b, 26b Turbine exhaust gas 22 Steam

Claims (3)

[Claims] In a power generation system for a gas turbine using methane gas as fuel, carbon monoxide and hydrogen are generated by bringing the methane gas into contact with carbon dioxide in a catalytic reactor, and the carbon monoxide and hydrogen are converted into gas. A gas turbine power generation system using methane gas, wherein the gas is burned by a turbine and the catalytic reactor is heated by heat generated by the combustion. 2. In a power generation system for a gas turbine using methane gas as fuel, carbon monoxide and hydrogen are generated by contacting the methane gas with steam in a catalytic reactor, and the carbon monoxide and hydrogen are converted into a gas turbine. A gas turbine power generation system using methane gas, characterized in that the catalyst reactor is heated by the heat generated by the combustion. 3. The gas turbine using methane gas according to claim 1, wherein said catalytic reactor is heated to about 600 ° C. using turbine exhaust gas, and a high-speed conversion catalyst is used as a catalyst for said catalytic reactor. Power generation system.