JPS62214235A - Gas turbine power generation system using methanol as fuel - Google Patents

Abstract

PURPOSE:To increase the recovering efficiency of exhaust heat by providing first and second methanol fuel feeding systems in the exhaust gas system of a low pressure gas turbine and feeding first and second combustors respectively. CONSTITUTION:First and second methanol fuel feeding systems 7, 11 are provided on the exhaust gas system 14 of a low pressure gas turbine 3. The first methanol feeding system 7 on an upper course side is fed to a first combustor 5 which is correspondent to a high pressure turbine 2. The second methanol feeding system 11 on a lower course side is fed to a second combustor 9 which is correspondent to a low pressure gas turbine 3. Thereby, an exhaust heat which became a low temp. can be efficiently recovered, increasing the recovering efficiency of an exhaust heat.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to an improvement in a gas turbine power generation system using methanol as fuel.

[Conventional technology]

Methanol, which is obtained by synthesizing natural gas and coal gas, is
At room temperature, it is in a liquid state, and in recent years, petroleum oil has become more advantageous for transportation, storage, and other handling.

It is attracting attention as an alternative fuel to petroleum.

However, from the table, on the other hand, since the raw material methanol itself has a relatively low calorific value, when compared with other common similar fuels9, such as LNG, it is necessary to obtain the same combustion calorific value. This method has the disadvantage of requiring about twice the amount of supply, and in order to compensate for this point, in the conventional case, heat or heat and steam are applied to the raw methanol in advance, and then the methanol is heated. Means have been adopted to increase the calorific value by decomposing or reforming (in both cases the heat of reaction is endothermic).

Here, a schematic configuration of a conventional gas turbine power generation system using methanol as fuel, which employs the above means, is shown in FIGS. 2 and 3.

2 and 3, reference numeral 21 is an air compressor, 22 is a high-pressure gas turbine coaxially connected to this air compressor 21, and 23 is a generator rotationally driven by this high-pressure gas turbine 22. and 24 is compressed air supplied from the air compressor 21 through the pipe line 25;
The raw material methanol as a fuel supplied through another pipe 26 is mixed and combusted, and the combustion gas energy is supplied to the high pressure gas turbine 22 through a pipe 27. Furthermore, a combustor that rotationally drives the generator 23, and 28 indicate a heat exchanger for exhaust heat recovery interposed in the exhaust gas pipe 29 of the high-pressure gas turbine 22, and in the configuration shown in FIG. By passing the raw material methanol supply pipe 26 through the vessel 28, the supplied raw material methanol is heated by the exhaust heat in the exhaust gas from the high-pressure gas turbine 22, causing a decomposition reaction and increasing the calorific value. In the configuration shown in FIG. 3, this heat exchanger 28 is connected to the feed line 26. Similarly, the water is heated through the water supply pipe 30 by the exhaust heat in the exhaust gas, and the steam obtained through the water supply pipe 20 is added to the heated raw material methanol to reform it. It is designed to increase the amount of heat generated.

[Problem that the invention seeks to solve]

That is, the conventional configuration shown in FIG. 2 is a case in which the above-described decomposition method is applied to the raw methanol, and the conventional configuration shown in FIG. 3 is a case in which a reforming method is similarly applied to each. However, the exhaust gas energy of the high-pressure gas turbine is recovered by the raw material methanol supplied as fuel, and this exhaust heat recovery gives the necessary reaction heat to the raw material methanol to increase the calorific value. The fuel improvement rate obtained in this way is:
The former decomposition method is approximately 22%, and the latter reforming method is approximately 154%.In each method, these methods involve improved chemical reactions, compared to the case where raw methanol is directly combusted. Both have a thermal efficiency of about 10% (relative value of about 3
It is possible to improve the performance by more than 0%.

In addition, although the fuel improvement rate of the latter reforming method is lower than that of the former cracking method, the reason why the two show the same value in terms of thermal efficiency is that in the case of the latter reforming method, the final It is thought that the amount of high-pressure gas supplied to the high-pressure gas turbine is increased by the amount of steam added, which ultimately exceeds the improvement rate of the fuel itself and contributes to an improvement in thermal efficiency.

In this type of gas turbine power generation system,
As a result, how to improve the efficiency of heat recovery from exhaust gas energy has a large impact on overall thermal efficiency improvement.However, in the case of each of the conventional systems mentioned above, no matter which method is used, It is possible to react at the exhaust gas energy temperature level without using some kind of catalyst. In addition, in order to efficiently decompose methanol using gas turbine exhaust heat and carry out the reformed gas reaction, a relatively low pressure is required, and a moderately high temperature range is not preferable from the viewpoint of the heat resistance of the catalyst.

In the near future, if technology advances to the level where the gas turbine inlet temperature reaches 1350 degrees Celsius, the supply pressure of decomposed and reformed gas will increase as the temperature of the gas turbine increases. There is a contradiction between the decomposition and reforming type gas turbine power generation that involves a reaction system using methanol gas turbine exhaust gas (high-temperature gas turbine) and methanol gas turbine exhaust gas.

Therefore, the purpose of this invention is to improve the heat recovery efficiency of exhaust gas energy by effectively utilizing existing technology (using existing catalysts, etc.), and to improve efficiency and efficiency through a simplified system configuration. It is an object of the present invention to provide a gas turbine power generation system using methanol as fuel, which is both large and reliable. If catalysts that can withstand high temperatures are developed in the future, it will be possible to provide even more efficient gas turbine power generation systems that use methanol as fuel.

[Means for solving problems]

To achieve the above object, the present invention includes an air compressor, a high-pressure gas turbine in the front stage, a low-pressure gas turbine in the rear stage, and a generator rotationally driven by the low-pressure gas turbine, which are coaxially connected to each other, and The exhaust gas system of the low-pressure gas turbine includes a first methanol fuel supply system on the upstream and relatively high temperature side.

Heat exchangers for exhaust heat recovery each having a second methanol fuel supply system arranged on the relatively low temperature side downstream, and compressed air from the air compressor and fuel supplied from the first fuel supply system. A first combustor that performs mixed combustion and supplies the combustion high-pressure gas to a high-pressure gas turbine, and a first combustor that performs mixed combustion of exhaust gas from the high-pressure gas turbine and fuel supplied from a second fuel supply system. Each of them is provided with a second combustor that supplies low-pressure gas to the low-pressure gas turbine.

[Effect]

That is, in the case of this invention, in the first combustor,
If a catalyst that can operate at high temperatures is developed, cracked or reformed gas obtained by heating methanol fuel to a relatively high temperature, or if only the current catalyst is available, preheated unreacted gas may be used as the fuel, or secondary In the combustor, the decomposed and reformed reaction gas obtained by heating methanol fuel at a relatively low temperature using an existing catalyst is used as fuel, and the former is used in a high-pressure gas turbine, and the latter is used in a low-pressure gas turbine. It is possible to rotate each of the methanol fuel, and use the combined rotational driving force to operate the generator to obtain the desired power generation effect. utilizes thermal energy obtained by recovering exhaust heat in the exhaust system.

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, one embodiment of a gas turbine power generation system using methanol as fuel according to the present invention will be described in detail with reference to FIGS. 1 and 4.

Fig. 1 is a block diagram showing the outline of the Kirinari equipment plant according to this embodiment, and Fig. 4 explains the heat recovery efficiency of exhaust gas energy between this embodiment plant and the conventional plant. It is a heat exchange characteristic diagram.

In this FIG. 1 embodiment configuration, reference numeral 1 denotes an air compressor;
2. and 3 are a front-stage high-pressure gas turbine and a rear-stage low-pressure gas turbine which are sequentially coaxially connected to the air compressor 1, and 4 is a generator rotationally driven by the low-pressure gas turbine 3. Further, 5 is a pipe line 6 from the air compressor 1.
The compressed air supplied through the first fuel supply pipe 7 and the fuel to be described later supplied through the first fuel supply pipe 7 are mixed and combusted, and the combustion gas energy is transferred to the high pressure gas turbine 2 through the pipe 8.
A first combustor 9 supplies the high pressure gas turbine 2 to the high pressure gas turbine 2.
Exhaust gas discharged through the pipe line 10 and fuel, which will be described later, supplied through the second fuel supply pipe line 11 are mixed and combusted, and the combustion gas energy is transferred to the low-pressure gas turbine 3 through the pipe line 12. This is the second combustor that supplies Furthermore, 13 is a heat exchanger for exhaust heat recovery that is interposed in the exhaust gas pipe 14 of the low-pressure gas turbine 3, and the first fuel supply pipe 7 is connected to the upstream relatively high temperature side, and the downstream side is connected to the first fuel supply pipe 7. The second fuel supply pipes 11 are respectively arranged on the relatively low temperature side.

However, in the case of the configuration of the embodiment shown in FIG. Through heat exchange with exhaust gas, exhaust heat is recovered and heat treated as follows.

That is, first, the first fuel supply pipe T, which is located upstream, that is, in a relatively high temperature atmosphere close to the exhaust gas inlet side, is heated to a relatively high temperature in advance, so that it is possible to use a high temperature catalyst here. If decomposed, reformed gas or high-temperature catalyst is not obtained, the preheated unreacted gas is used, and the downstream temperature is lowered by heat exchange in this first fuel supply pipe 7.

In this case, in the second fuel supply pipe 11 which is located in a relatively low temperature atmosphere close to the exhaust gas outlet side, the conventional catalyst can be relatively well decomposed or improved under low pressure because of the relatively low temperature. , here it becomes a reactive gas.

In this embodiment configuration in FIG. 4, the first combustor 5
In this case, the apparatus air composed of the air compressor 1 and the decomposed or reformed gas as a fuel or the preheated unreacted gas supplied from the first fuel supply pipe 7 are mixed and combusted. High-pressure gas turbine 2 powered by combustion gas energy
In addition, in the second combustor 9, the exhaust gas discharged from the high-pressure gas turbine 2 is mixed with reaction gas as a fuel, which is also supplied separately from the second fuel supply pipe 11. The combustion gas energy is used to rotate the low-pressure gas turbine 3 and, in turn, the generator 4, thereby obtaining the desired power generation effect. When the reformed gas is supplied to the first combustor or the second combustor, the H20 partial pressure of the combustion gas is high due to the composition of the reformed gas.
There is a possibility that the oxygen concentration in the second combustor becomes low, and in that case, combustion may not be possible regardless of the concentration. In order to avoid this, it is necessary to control the amount of reforming steam, but this is not shown in the figure.

The essence of the present invention is to recover as much energy from gas turbine exhaust gas as possible to achieve high efficiency in gas turbine power generation using methanol fuel.As a measure to achieve this, the heat exchange process of the exhaust gas energy recovery system is basically used. The combustor is divided into two parts, and the fuel generated in each part is guided to a high-pressure combustor and a low-pressure combustor, respectively.The heat exchange characteristics will be described below.

Here, in the heat exchange characteristics shown in FIG. 4, the dotted line Bl
+ and B2 are the temperature drop characteristics of the exhaust gas based on exhaust heat recovery in the conventional method described above, and the heating or reaction temperature characteristics of the raw material methanol, and the solid lines AI+ and A2+A3 are the Temperature drop characteristics of exhaust gas based on exhaust heat recovery.

and 1st. These are the heating reaction temperature characteristics of the raw material methanol in the second fuel supply pipes 7 and 11, respectively.

That is, as is clear from the heat exchange characteristics shown in FIG. 4, in principle, in the case of a conventional system plant, the exhaust gas temperature TI at the inlet of the heat exchanger 28
Through heat exchange with the raw material methanol passing through 6, the temperature decreases to Te2 at the outlet, and conversely, the raw material methanol changes from point b1 at room temperature to b2 → b3 → b4 →
The temperature increases by absorbing heat at the temperature t3t. Here again, the temperature 1° is the evaporation temperature, the so-called saturation pressure, based on the pressure required for the combustor 24 of the high-pressure gas turbine 22. When setting the pinch point temperature difference Δ'rp at the above point b2 to a constant temperature, the value of the exhaust gas outlet (release) temperature Te2 is automatically determined. In other words, in the conventional system, the exhaust gas release temperature Te2 is still at a low temperature level, resulting in a large energy loss.

On the other hand, in the case of the apparatus plant according to the method of this embodiment, the heat absorbed by the raw material methanol in the first fuel supply pipe 7 is at room temperature t, as in the conventional method.

The temperature rises from point Ikl to point &4 at temperature t3 via point a2 + 13 on the saturation pressure tl corresponding to the pressure of the first combustor 5, and also separately in the second fuel supply pipe 11. The heat absorption of the raw material methanol causes the temperature to rise from point 1 +1 at room temperature to to point a14 at temperature t4 via point a12 + ata on evaporation temperature +2 corresponding to the operating pressure of the second combustor 9, and as a result In this embodiment system, the exhaust gas temperature TI at the inlet of the heat exchanger 13 drops to the exhaust gas discharge temperature Tel, which is sufficiently lower than that in the conventional system. In this case, Te l >Te2, and the difference is large, so that energy loss can be kept to a minimum. In this case, it is effective to set the pinch point temperature differences Δ'rp, which are the differences between the evaporation start point temperature t1 + +2 and the corresponding exhaust gas temperature, to be approximately the same.

In other words, in the heat exchanger 13 for exhaust heat recovery, the exhaust gas is Heat recovery efficiency.

As a result, the thermal efficiency of raw methanol can be sufficiently improved.

〔Effect of the invention〕

As described in detail above, when the system configuration of the present invention is used, the air compressors are coaxially connected to each other.

A high-pressure gas turbine at the front stage, a low-pressure gas turbine at the rear stage, and a generator rotationally driven by the low-pressure gas turbine are provided, and the exhaust gas system of the low-pressure gas turbine includes a first methanol gas turbine on the upstream relatively high temperature side. A heat exchanger for exhaust heat recovery is installed, which is equipped with a fuel supply system and a second methanol fuel supply system on the relatively low-temperature side downstream, and a heat exchanger for recovering compressed air from the air compressor and a second methanol fuel supply system on the relatively low-temperature side of the downstream side. A first combustor that mixes and burns the supplied fuel and supplies the combustion high pressure gas to the high pressure gas turbine, and mixes and burns the exhaust gas from the high pressure gas turbine and the fuel supplied from the second fuel supply system. A second combustor was installed in each of the combustion chambers to supply the combustion low-pressure gas to the low-pressure gas turbine.In the first combustor, the methanol fuel was heated to a relatively high temperature and the decomposed and reformed gas was heated to a relatively high temperature. Gas or preheated unreacted gas is used as fuel, and in the second combustor, decomposed and reformed reaction gas obtained by heating methanol fuel to a relatively low temperature is used as fuel; The turbine and the latter can drive the low-pressure gas turbine to rotate, and the combined rotational driving force can operate the generator to obtain the desired electric power. The heat treatment of the methanol fuel here utilizes the thermal energy obtained by exhaust heat recovery in the exhaust system, and by adding the second combustor, the temperature is significantly lowered. Since the exhaust heat can be used synergistically and effectively, the thermal efficiency of the raw material methanol as fuel can be significantly improved.In addition, the entire system is relatively simple in terms of configuration. It has excellent features such as being easy to implement.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of a gas turbine power generation system using methanol as fuel according to the present invention, and FIGS. 2 and 3 are schematic configurations of conventional individual gas turbine power generation systems as described above. FIG. 4 is a heat exchange characteristic diagram illustrating the heat recovery efficiency of exhaust gas energy between the embodiment system and the conventional system. 1... Air compressor, 2... High pressure gas turbine,
3...Low pressure gas turbine, 4...Generator, 5...
...first combustor, 7...φ, first methanol fuel supply system, 7'...water supply system for reforming reaction, 9...second combustor, 11... - Second methanol fuel supply system, 13... heat exchanger for exhaust heat recovery, 14... exhaust gas system.

Claims (1)

[Claims] (1) An air compressor, a high-pressure gas turbine at the front stage, a low-pressure gas turbine at the rear stage, which are coaxially connected to each other, a generator rotationally driven by the low-pressure gas turbine, and an exhaust gas system of the low-pressure gas turbine. a heat exchanger for exhaust heat recovery, in which a first methanol fuel supply system is disposed on the upstream relatively high temperature side and a second methanol fuel supply system is disposed on the downstream relatively low temperature side; Compressed air supplied from the air compressor and decomposed or reformed gas heated to a relatively high temperature or preheated unreacted gas supplied from the first fuel supply system are mixed and combusted to produce high-pressure gas from the combustion. a first combustor that supplies gas to the high-pressure gas turbine, exhaust gas from the high-pressure gas turbine, and decomposed and reformed reaction gas heated to a relatively low temperature supplied from the second fuel supply system. A gas turbine power generation system using methanol as fuel, comprising a second combustor that performs mixed combustion and supplies the combustion low pressure gas to the low pressure gas turbine.