JP2004060471A - Power unit and power generating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To further heighten the temperature of exhaust gas supplied to a reformer as a heat source. <P>SOLUTION: This power unit is provided with a first turbine 3A rotationally driven by first combustion gas; a second turbine 3B rotationally driven by second combustion gas; a compressor 1 compressing gas containing oxygen and outputting compressed gas containing oxygen; a steam generator 7 vaporizing water using exhaust gas from the second turbine 3B to output steam; the reformer 5 reacting hydrocarbon and steam using the exhaust gas from the second turbine 3B to output reformed gas; a first combustor 2 burning fuel gas together with the compressed gas containing oxygen and the reformed gas to output the first combustion gas to the first turbine 3A; and a second combustor 4 burning the reformed gas together with the exhaust gas from the first turbine 3A to output the second combustion gas to the second turbine 3B. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a power plant and a power generation method.
[0002]
Problems to be solved by the prior art and the invention
For example, Japanese Patent Application Laid-Open No. 2000-328960 discloses a gas turbine system (power unit) that uses exhaust heat from a simple cycle gas turbine for reforming fuel. In this gas turbine system, the exhaust gas of the gas turbine is supplied to the reformer as a heat source, so that the exhaust gas of the exhaust gas is used to react the fuel gas with steam to generate a reformed gas. The gas turbine is supplied to a combustor and burned together with steam and compressed air to rotationally drive the gas turbine.
[0003]
By the way, in the above gas turbine system, the temperature of the exhaust gas discharged from the gas turbine is about 750 K (Kelvin), and the fuel gas is not sufficiently reformed. That is, the gas turbine system has poor efficiency as a power unit because of poor fuel gas reforming efficiency. Also, poor fuel gas reforming efficiency is equivalent to low hydrogen gas concentration in the reformed gas, so a large amount of steam is supplied to the combustor to improve the efficiency of the power plant. As a result, there is also a problem that the combustor is easily misfired.
[0004]
The present invention has been made in view of the above problems, and has the following objects.
(1) The temperature of the exhaust gas supplied to the reformer as a heat source is further increased.
(2) Improve power generation efficiency.
(3) Prevent misfire of the combustor.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, as a first means relating to a power plant, a first turbine (3A) rotationally driven by a first combustion gas, and a rotationally driven by a second combustion gas. A second turbine (3B), a compressor (1) for compressing the oxygen-containing gas and outputting a compressed oxygen-containing gas, and vaporizing water by using the exhaust gas of the second turbine (3B) to output steam. A steam generator (7), a reformer (5) for reacting a hydrocarbon with the steam using the exhaust gas of the second turbine (3B) to output a reformed gas, A first combustor (2) for burning the first combustion gas to the first turbine (3A) by burning with the contained gas and the reformed gas, and burning the reformed gas together with the exhaust gas of the first turbine (3A) Then, the second combustion gas is To adopt a configuration comprising a second combustor output to down (3B) and (4).
[0006]
As a second means relating to the power plant, in the first means, when the ratio of steam to hydrocarbon in the reformer (5) is set to a predetermined value or more, the second combustor (4) is subjected to catalytic combustion. It adopts the configuration of a container.
[0007]
As a third means relating to the power plant, the first or second means may be a second turbine (3B) in which the mixed gas obtained by mixing the steam output from the steam generator (7) and the compressed oxygen-containing gas is mixed. The structure is further provided with a heat exchanger (6) that heats the exhaust gas and supplies it to the first combustor (2).
[0008]
As a fourth means relating to the power unit, in any one of the first to third means described above, a preheater for preheating water using exhaust gas from the second turbine (3B) and supplying the preheated water to a steam generator (7). 8) is adopted.
[0009]
As a fifth means related to the power unit, in any of the first through fourth means, hydrocarbons employs a configuration that mainly methane (CH _4).
[0010]
On the other hand, in the present invention, as a first means related to a power generation method, when a gas turbine is rotationally driven to generate power, a reaction between hydrocarbons and steam is performed by utilizing heat energy in exhaust gas of the gas turbine. A power generation method for generating a reformed gas, burning the reformed gas together with a fuel gas, and rotatingly driving the gas turbine, wherein a reheat cycle gas turbine (T) is used as the gas turbine. Is adopted.
[0011]
As a second means relating to the power generation method, in the first means, when the reformed gas is generated by setting the ratio of steam to hydrocarbon to a predetermined value or more, the reformed gas is caused to act on the catalyst. In this case, the fuel gas is burned together with the fuel gas.
[0012]
As a third means relating to a power generation method, in the above first or second means, a mixed gas obtained by mixing steam and a compressed oxygen-containing gas is heated using exhaust gas of a gas turbine, and the heated gas is heated. A configuration in which combustion is performed together with the reformed gas and the fuel gas is employed.
[0013]
As a fourth means relating to the power generation method, in any one of the first to third means, a configuration is adopted in which water is preheated by using exhaust gas from a gas turbine and then further heated to generate steam. .
[0014]
As a fifth means relating to the power generation method, in any one of the first to fourth means, a configuration is employed in which the hydrocarbon is mainly methane (CH ₄ ).
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a power plant and a power generation method according to the present invention will be described with reference to the drawings.
[0016]
FIG. 1 is a system configuration diagram of a power unit according to the present embodiment. In this figure, reference symbol T denotes a reheat cycle gas turbine (gas turbine), which includes a compressor 1, a first combustor 2, a first turbine 3A, a second turbine 3B, and a second combustor 4. I have. Reference numeral 5 denotes a reformer, 6 denotes a heat exchanger, 7 denotes a steam generator, and 8 denotes a preheater. The compressor 1 rotates coaxially with the first turbine 3A, compresses air (oxygen-containing gas) supplied from the outside, and converts the compressed air (compressed oxygen-containing gas) into the first combustor 2 and the heat exchanger. 6 is output. The first combustor 2 burns fuel supplied from the outside together with the compressed air, the reformed gas supplied from the reformer 5, and the mixed gas supplied from the heat exchanger 6 to generate a high-pressure combustion gas ( The first combustion gas is generated, and the first combustion gas is output to the first turbine 3A.
[0017]
The first turbine 3 </ b> A is driven to rotate by the first combustion gas, and outputs exhaust gas that has contributed to the driving to the second combustor 4. The second turbine 3B is driven to rotate by the combustion gas (second combustion gas) supplied from the second combustor 4, and the exhaust gas that has contributed to the driving is subjected to the reformer 5, the heat exchanger, and the like. 6. Output to the steam generator 7 and the preheater 8 as a heat source. The second turbine 3B rotates coaxially with the first turbine 3A, but may have a structure that does not rotate coaxially.
[0018]
The second combustor 4 generates a high-pressure combustion gas (second combustion gas) by burning the reformed gas supplied from the reformer 5 together with the exhaust gas input from the first turbine 3A. The second combustion gas is output to the second turbine 3B. The reformer 5 uses the exhaust gas supplied from the second turbine 3B as a heat source to react hydrocarbons supplied from the outside with steam supplied from the steam generator 7 to generate a reformed gas. The gas is output to the first combustor 2 and the second combustor 4.
[0019]
The heat exchanger 6 heats a mixed gas of the compressed air output from the compressor 1 and the steam output from the steam generator 7 by exchanging heat with the exhaust gas supplied from the second turbine 3B, and heats the mixed gas. Is output to the first combustor 2. The steam generator 7 vaporizes the heated water supplied from the preheater 8 by using heat (exhaust heat) of the exhaust gas supplied from the second turbine 3B to generate steam, and converts the steam into a reformer. 5 and the heat exchanger 6. The preheater 8 heats (preheats) water (tap water) supplied from the outside using exhaust gas supplied from the second turbine 3 </ b> B, and outputs the water to the steam generator 7.
[0020]
Next, the operation and performance of the power unit thus configured will be described in detail with reference to FIG.
[0021]
In such a power plant, motive power is generated when the first turbine 3A is rotationally driven by the high-pressure first combustion gas supplied from the first combustor 2. The first combustion gas, which has lost energy by contributing to the power generation, is supplied as exhaust gas from the first turbine 3A to the second combustor 4 and burns together with the reformed gas to perform high-pressure second combustion. Gas. The second turbine 3B receives the supply of the second combustion gas to generate power, and outputs the exhaust gas to the reformer 5, the heat exchanger 6, the steam generator 7, and the preheater 8 as a heat source.
[0022]
Here, the Kelvin temperature of the second combustion gas output from the second turbine 3B is about 1000K. The reformer 5, the heat exchanger 6, the steam generator 7, and the preheater 8 realize the above-described desired functions by using exhaust gas of about 1000K as a heat source.
[0023]
That is, the reformer 5 generates a reformed gas by reacting the hydrocarbon with the steam using the heat (exhaust heat) of the exhaust gas having a high temperature of about 1000K. For example, when using methane (CH ₄₎ in the hydrocarbon, the methane (CH ₄₎ is reacted with water vapor _(H 2 O), one carbide oxygen gas (CO) and hydrogen gas _{(H 2)} and the component Is generated. Therefore, in the first combustor 2, one carbide oxygen gas and the fuel gas and air which is a component of the reformed gas (CO) and hydrogen gas (H ₂₎ as well as mixtures is a component of a gas heated steam (H ₂ Combustion is performed in a state where O) and air are mixed. The high-pressure first combustion gas generated by the combustion reaction in the first combustor 2 is supplied to the first turbine 3a to generate rotational power.
[0024]
The exhaust gas of the first turbine 3A is supplied to the second combustor 4 and burns in a state where the exhaust gas is mixed with the reformed gas containing the above-mentioned monocarboxy gas (CO) and hydrogen gas (H ₂ ) as components. The high-pressure second combustion gas is supplied to the second turbine 3B to generate rotational power. Then, the exhaust gas (about 1000K) of the second turbine 3B that has contributed to the generation of the rotational power is supplied to the reformer 5, the heat exchanger 6, the steam generator 7, and the preheater 8, and acts as a heat source.
[0025]
FIG. 2 is a characteristic diagram illustrating the reforming efficiency of the reformer 5 with respect to a change in hydrocarbon temperature. In this figure, the temperature range T1 indicates the temperature range of the exhaust gas of the simple cycle gas turbine, and the temperature range T2 indicates the temperature range of the exhaust gas of the reheat cycle gas turbine T in the power plant. Here, the reforming efficiency is the ratio of the amount of hydrocarbons fed into the reformer 5 to the amount of reformed hydrocarbons discharged from the reformer 5.
[0026]
That is, while the temperature region T1 is approximately 750K to 850K, the temperature region T2 is approximately 1000K, which is approximately 200K higher than the temperature region T1. The four characteristic curves R1 to R4 show the change of the reforming efficiency with respect to the temperature using the amount of steam at the time of reforming as a parameter. Note that the amount of water vapor has a relationship of R1>R2>R3> R4. From this characteristic diagram, it is found that the reforming efficiency is higher in the exhaust gas temperature range of the reheat cycle gas turbine T than in the exhaust gas temperature range of the simple cycle gas turbine, and that the amount of steam is larger when compared at the same temperature. It can be seen that the reforming efficiency is high.
[0027]
Therefore, by using the reheat cycle gas turbine T as in the present power plant, the reforming efficiency of hydrocarbons can be improved even when a simple cycle gas turbine is used. According to the present power plant, the efficiency of power generation can be improved by improving the reforming efficiency in this way.
[0028]
In addition, the improvement of the reforming efficiency means that the reforming reaction of hydrocarbons using steam is an endothermic reaction, and thus the exhaust gas supplied to the reformer 5 from the reheat cycle gas turbine T is improved. Since the thermal energy is used more in the reforming reaction, the utilization efficiency of the thermal energy of the exhaust gas is increased, and the overall energy efficiency of the power plant can be improved.
[0029]
Furthermore, even when the reheat cycle gas turbine T is used, the larger the amount of steam fed to the reformer 5, the higher the reforming efficiency (ie, the higher the power generation efficiency). The amount of water vapor should be set as high as possible. However, if the amount of steam supplied to the reformer 5 is increased, the amount of unreacted steam contained in the reformed gas increases, and thus such reformed gas is supplied to the first combustor 2 and the second combustor. In the case where the fuel is supplied to 4, the possibility of a misfire increases. In order to prevent such an adverse effect, in the present embodiment, a misfire of the second combustor 4 due to an increase in the amount of water vapor is prevented by using a catalytic combustor in which the catalyst is interposed in the combustion reaction in the second combustor 4. Can be.
[0030]
When reforming is performed using such a large amount of steam, the reformed gas cannot be burned in the first combustor 2 having a low air temperature. That is, even if a catalytic combustor is used for the first combustor 2, combustion is difficult because the catalyst is activated due to the low air temperature. Therefore, when reforming is performed using a large amount of steam, the second combustor 4 is used as a catalytic combustor, and the reformed gas is supplied to only the second combustor 4 and burned. Since the second combustor 4 has a lower pressure than the first combustor 2, the reforming can be performed at a lower pressure, and as a result, the reforming efficiency is improved.
[0031]
In the heat exchanger 6, the mixed gas of the compressed air and the steam is heated by using the exhaust gas of the second turbine 3 </ b> B as a heat source and supplied to the first combustor 2. Similarly, in the steam generator 7, the water preheated by the preheater 8 is vaporized by using the exhaust gas of the second turbine 3 </ b> B as a heat source, converted into steam, and supplied to the inlet pipes of the reformer 5 and the heat exchanger 6. Is done.
[0032]
The hydrocarbon is not limited to methane, but may be kerosene, naphtha or LPG.
[0033]
【The invention's effect】
As described above, according to the present invention, the first turbine rotationally driven by the first combustion gas, the second turbine rotationally driven by the second combustion gas, and the oxygen-containing gas are compressed and compressed. A compressor that outputs an oxygen-containing gas, a steam generator that vaporizes water using the exhaust gas of the second turbine and outputs steam, and a reformer that reacts hydrocarbons and steam using the exhaust gas of the second turbine. A first combustor for burning the fuel gas together with the compressed oxygen-containing gas and the reformed gas to output the first combustion gas to the first turbine; A second combustor that burns together with the exhaust gas of the turbine and outputs a second combustion gas to the second turbine.
That is, since the reformed gas is generated by the reformer using the exhaust gas of the reheat cycle gas turbine as a heat source instead of the conventional simple cycle gas turbine, it is necessary to generate the reformed gas in a higher temperature environment than before. Therefore, it is possible to improve the reforming efficiency in the reformer. As a result, the power generation efficiency can be improved.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of a power unit according to an embodiment of the present invention.
FIG. 2 is a characteristic diagram illustrating a hydrocarbon reforming efficiency in one embodiment of the present invention.
[Explanation of symbols]
T: Reheat cycle gas turbine (gas turbine)
1 Compressor 2 First combustor 3A First turbine 3B Second turbine 4 Second combustor 5 Reformer 6 Heat exchanger 7 Steam generator 8 …… Preheater

Claims (10)

A first turbine (3A) rotationally driven by a first combustion gas;
A second turbine (3B) rotationally driven by the second combustion gas;
A compressor (1) for compressing an oxygen-containing gas and outputting a compressed oxygen-containing gas;
A steam generator (7) for evaporating water using the exhaust gas of the second turbine (3B) and outputting steam.
A reformer (5) that outputs a reformed gas by reacting a hydrocarbon with the steam using exhaust gas of the second turbine (3B);
A first combustor (2) that burns a fuel gas together with the compressed oxygen-containing gas and the reformed gas and outputs the first combustion gas to a first turbine (3A);
A second combustor (4) for burning the reformed gas together with the exhaust gas of the first turbine (3A) and outputting a second combustion gas to the second turbine (3B). apparatus. The power plant according to claim 1, wherein the second combustor (4) is a catalytic combustor when the ratio of steam to hydrocarbons is equal to or more than a predetermined value in the reformer (5). Heat exchange in which a mixed gas obtained by mixing steam and a compressed oxygen-containing gas output from the steam generator (7) is heated using exhaust gas of the second turbine (3B) and supplied to the first combustor (2) Power plant according to claim 1 or 2, further comprising a vessel (6). The power plant according to any one of claims 1 to 3, further comprising a preheater (8) for preheating water using exhaust gas of the second turbine (3B) and supplying the preheated water to the steam generator (7). . Power plant according to any one claims 1 to 4 hydrocarbons, characterized in that the main component of methane (CH _4). When power is generated by driving the gas turbine to rotate, hydrocarbons and steam are reacted with each other using thermal energy in the exhaust gas of the gas turbine to generate a reformed gas, and the reformed gas is used together with the fuel gas. A method for generating power for rotating and driving the gas turbine by burning,
A power generation method using a reheat cycle gas turbine (T) as the gas turbine. 8. The power generation system according to claim 7, wherein when the ratio of steam to hydrocarbon is set to a predetermined value or more and the reformed gas is generated, the reformed gas is caused to act on a catalyst and burned together with the fuel gas. Method. The mixed gas obtained by mixing steam and a compressed oxygen-containing gas is heated by using exhaust gas of a gas turbine, and the heated gas is burned together with a reformed gas and a fuel gas. Power generation method. The power generation method according to any one of claims 7 to 9, wherein the water is further heated after preheating the water using exhaust gas of the gas turbine to generate steam. The power generation method according to claim 7-10 hydrocarbons, characterized in that the main component of methane (CH _4).

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