JP2003090231A - Reformed fuel burning gas turbine and purge method of its fuel system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress clogging in a fuel supply system in the case of switching reformed fuel and light fuel in a reformed fuel burning gas turbine of heavy oil. SOLUTION: A combustor for switching reformed fuel and light fuel to be burnt is provided, to have a means, in the case of switching from this reformed fuel to this light fuel, after stopping supply of this reformed fuel, supplying supercritical or sub-critical steam to a reformed fuel supply system to purge heavy fuel left in this reformed fuel supply system, or to have a means, in the case of switching from this light fuel to this reformed fuel, after stopping supply of this light fuel, supplying supercritical or sub-critical steam to a light fuel supply system to purge light fuel left in this light fuel supply system. Accordingly, clogging of the fuel supply system is suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine, and more particularly, to a gas turbine that is lightened by supercritical water or supercritical steam and is operated with the reformed fuel, and a fuel system purging method thereof. Involved in.

[0002]

2. Description of the Related Art A conventional method of purging a gas turbine for burning light fuel such as kerosene and light oil when the gas turbine is stopped is, for example, to control the supply amount of light oil by a light oil control valve when the gas turbine is stopped. There is. Then, the parts exposed to the high temperature air, such as the fuel nozzle of the combustor, are still around 400 ° C. immediately after the gas turbine is stopped. When the light oil remains in the fuel nozzle, residual heat may polymerize the unsaturated components in the fuel to form a gum-like substance, which may cause nozzle clogging. In order to prevent this, conventionally, air is generally compressed by an air compressor, air is supplied to a light oil fuel system, and residual light oil is removed.

[0003]

SUMMARY OF THE INVENTION In a gas turbine for burning a reformed fuel of a heavy oil, the heavy oil has a high proportion of an olefin component and an aroma component which are easily polymerized under high temperature conditions to easily produce a gum-like substance. . Even when reformed, it is difficult to completely lighten the olefin component and the aroma component, and a certain amount of the component is transported to the fuel supply system. for that reason,
Compared with the conventional light fuel, the reformed fuel remaining in the fuel supply system is likely to polymerize and cause clogging in the system.

In the case of purging with air or nitrogen as in the conventional case, since the action of cooling the remaining reformed fuel is strong,
Polymerization may occur at a portion in contact with a portion having residual heat such as a fuel nozzle. In particular, when the reformed fuel stays at a portion having a joint or a step, such as a joint between the fuel nozzle and the supply pipe, the above-mentioned polymerization action becomes remarkable.

An object of the present invention is to suppress clogging of the fuel supply system at the time of switching between the reformed fuel and the light fuel in a gas turbine that burns heavy fuel reformed fuel.

[0006]

DISCLOSURE OF THE INVENTION The present invention is a gas turbine equipped with a combustor for switching between a reformed fuel obtained by lightening heavy oil by supercritical steam and a light fuel and burning them according to the load. , When switching from the reformed fuel to the light fuel, supplying supercritical or subcritical steam to the reformed fuel supply system after the supply of the reformed fuel is stopped, and the heavy fuel remaining in the reformed fuel supply system It is characterized by having means for purging fuel.

Alternatively, the present invention is a gas turbine equipped with a combustor for switching between a reformed fuel obtained by lightening heavy oil by supercritical steam and a light fuel according to the load, and burning the light fuel. In the case of switching from the reforming fuel to the reforming fuel, a means for supplying supercritical or subcritical vapor to the light fuel supply system after stopping the supply of the light fuel and purging the light fuel remaining in the light fuel supply system is provided. Is characterized by.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, FIG. 2 shows a purging method when a gas turbine for burning light fuel such as general light oil is stopped when the gas turbine is stopped. In FIG. 2, 1 is a compressor, 2 is a turbine, 3 is a combustor, 4 is air, 12 is a light fuel, 19 is a light oil fuel control valve, 23 is a light oil fuel supply system, 25 is an air compressor, 26 Is an air supply system and 27 is air.

When the gas turbine is stopped, the light oil fuel control valve 19 controls the supply amount of the light fuel 12 to stop it. Parts exposed to high-temperature air, such as the fuel nozzle of the combustor 3, are
It is around 00 ° C. Light fuel 12 in the fuel nozzle
In the case of remaining, the unsaturated components in the fuel are polymerized by the residual heat to generate a gum-like substance, which may cause nozzle clogging. To prevent this, air is compressed by the air compressor 25 and the air 27 is supplied to the air supply system 26.
The conventional general fuel purging method is to remove the remaining light fuel by supplying it to the fuel tank.

The first heavy oil reformed fuel burning gas turbine according to the embodiment of the present invention has a device for generating supercritical steam and a reformer for lightening the heavy oil by the supercritical steam. However, in a gas turbine driven by high temperature gas from a combustor that switches and burns light fuel and the reformed fuel depending on the load, when the reformed fuel is switched to the light fuel, the reformed fuel supply is stopped. After that, only the supercritical or subcritical steam is allowed to flow into the reformer and the system for supplying the reformed fuel to the combustor, and the heavy fuel remaining in the reformer and the supply system is purged.

Supercritical vapor has an extremely strong action of dissolving organic substances, and has a function of easily decomposing the dissolved organic substances. The reformed fuel reforms heavy oil with supercritical steam. When switching to light fuel, the supply of fuel to the reforming reactor is cut off and only supercritical steam is supplied. The supercritical steam that has passed through the reforming reactor flows out to the combustor burning the light fuel through the reforming fuel supply system. Since supercritical vapor is chemically very active as described above,
The heavy oil remaining in the fuel supply system is easily dissolved and decomposed. The steam containing the dissolved heavy oil flows out to the gas turbine after the heavy oil is completely burned by the light oil combustion gas in the combustor. As a result, it is possible to suppress and prevent polymerization even at a portion in contact with a portion having residual heat such as a fuel nozzle.

A second heavy oil reformed fuel-fired gas turbine according to an embodiment of the present invention provides a light fuel supply when switching from a light fuel such as light oil to a reformed fuel in the first invention. It is configured by supplying supercritical or subcritical steam also to the light fuel supply system after the stop, and purging the light fuel remaining in the supply system.

Some light oils contain the olefin component and the aroma component described in the above-mentioned problems. For example, light oil called light cycle oil, which is cheaper than conventional kerosene, is being used as a gas turbine fuel. Light cycle oil contains about 70% aroma components. When such a light oil is seat-saved in the supply system and the fuel nozzle and is heated, there is a risk of clogging due to polymerization, like the reformed fuel. By supplying supercritical steam to the light oil supply system, polymerization of light fuel can be suppressed and prevented.

A third heavy oil reformed fuel burning gas turbine according to the embodiment of the present invention is the supercritical or subcritical supply system for the reformed fuel and the light fuel in the first and second inventions. It is constituted by purging with steam and then with air or nitrogen.

When purging with supercritical steam or subcritical steam, when the gas turbine is cooled while the steam remains in the fuel supply system, the phase of the steam is changed to water, and the steam in the fuel supply system and the fuel nozzle is changed. It is expected that rust will occur on the. The rust also causes the clogging of the supply system and the fuel nozzle. After the steam purge, by purging the drain remaining in the supply system with nitrogen or air,
The generation of rust can be suppressed and prevented.

(First Embodiment) A first embodiment of the present invention will be described below with reference to FIGS. 1 and 3. In FIG. 1, 1 is a compressor, 2 is a turbine, 3 is a combustor, 4 is air, 5 is high temperature exhaust gas, 6 is an exhaust heat recovery boiler, 7 is water, 8 is supercritical steam, 9 is heavy oil, 10 is a reformer, 11 is a reformed fuel, 12
Is a light fuel, 16 is a combustion gas, 17 is a reformed fuel supply system, 18 is a heavy oil control valve, 19 is a light oil fuel control valve, 20 is a reformed fuel purge line,
21 and 22 are control valves for reforming fuel.
In FIG. 3, 4 is air, 13 is a fuel nozzle for light oil,
14 is a fuel nozzle for reforming fuel, 15 is a swirler, 16
Is combustion gas.

FIG. 3 shows a detailed structure of the combustor 3 shown in FIG. In this embodiment, the air 4 compressed by the compressor 1 and the light fuel 12 are activated. Air 4
The turbine 2 is driven by the combustion gas 16 of light fuel.
Exhaust gas 5 after driving the turbine 2 exchanges heat with water 7 in an exhaust heat recovery boiler 6 to generate supercritical steam 8.
When the supercritical steam suitable for reforming is obtained, the supercritical steam and the heavy fuel 9 are supplied to the reformer to produce the reformed fuel 11.

Up to a certain partial load operation, the reformed fuel 11
Control valve 2 because the composition of is not suitable for combustion
2 is closed, the control valve 21 is opened, and it is discarded into the purge line 20. When the load increases and the composition of the reformed fuel 11 becomes stable, the control valve 21 is closed, the valve 22 is opened to supply the reformed fuel 11 to the combustor 3, and at the same time the light fuel 12 is controlled by the valve 19. The gas turbine is operated only with the reformed fuel 11.

On the contrary, when the load decreases, the control valve 19 for the light oil fuel is opened to supply the light fuel 12, and at the same time, the control valve 22 for the reformed fuel is closed to the combustor of the reformed fuel 11. Is stopped and the valve 21 is opened to discharge the reformed fuel to the reformed fuel purge line 20. The exhaust heat from the light fuel 12 is used to continuously generate the supercritical steam 8 in the exhaust heat recovery boiler 6.

When the supply of the reformed fuel 11 is stopped, the heavy fuel 9
Is stopped and only the supercritical steam 8 is supplied to the reformer 10. The supercritical steam 8 passes straight through the reformer 10 and first sufficiently purges the flow path of the reformed fuel purge line 20. Then, by closing the control valve 21 and opening the control valve 22, the supercritical steam 8 flows into the combustor 3 via the fuel supply system 17. By injecting the supercritical steam 8 in which the heavy oil 9 remaining in the reformed fuel supply system 17 is dissolved into the combustion gas 16 of the light fuel 12 and the air 4 in the combustor 3, the heavy fuel 11 Is completely burned and then flows out to the turbine 2.

According to the present embodiment, when switching from the reformed fuel to the light fuel, the heavy fuel remaining in the reformed fuel supply system can be easily injected by injecting the supercritical steam into the reformed fuel supply system. Can be dissolved and decomposed in the fuel supply system, and the residual heavy oil due to residual heat in the fuel supply system can be suppressed and prevented from being polymerized, and the reformed fuel supply system can be prevented from being clogged due to the polymerization.

On the contrary, when switching from the light fuel to the reformed fuel, by injecting the supercritical steam also into the light fuel supply system, the residual light fuel in the supply system is melted and decomposed, and the residual heat is removed. It is possible to suppress and prevent the polymerization of the remaining light fuel due to the above, and eventually to suppress and prevent the clogging of the light fuel supply system due to the polymerization.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to FIG. In FIG. 4, 1 is a compressor, 2 is a turbine, 3 is a combustor, 4 is air, 5 is high temperature exhaust gas, 6 is an exhaust heat recovery boiler, 7 is water, 8 is supercritical steam, 9 is heavy oil, 10 Is a reformer, 11 is a reformed fuel, 12 is a light fuel,
Reference numeral 16 is a combustion gas, 17 is a reformed fuel supply system, 18 is a heavy oil control valve, 19 is a light oil fuel control valve, 20 is a reformed fuel purge line, 21 and 22 are reformed fuel control valves, and 23 is A light oil fuel supply system, and 24 is a supercritical steam control valve for the light oil supply system.

The combustor 3 shown in FIG. 4 has the same structure as that shown in FIG. In this embodiment, the air 4 compressed by the compressor 1 and the light fuel 12 are activated. The turbine 2 is driven by the air 4 and the combustion gas 16 of the light fuel. Exhaust gas 5 after driving the turbine 2 exchanges heat with water 7 in an exhaust heat recovery boiler 6 to generate supercritical steam 8. When the supercritical steam suitable for reforming is obtained, the supercritical steam and the heavy fuel 9 are supplied to the reformer to produce the reformed fuel 11.

Up to a certain partial load operation, the reformed fuel 11
Control valve 2 because the composition of is not suitable for combustion
2 is closed, the control valve 21 is opened, and it is discarded into the purge line 20. When the load increases and the composition of the reformed fuel 11 becomes stable, the control valve 21 is closed, the valve 21 is opened to supply the reformed fuel 11 to the combustor 3, and at the same time the light fuel 12 is controlled by the valve 19. The gas turbine is operated only with the reformed fuel 11. Then, the valve 24 is opened to supply the supercritical steam 8 to the light oil fuel supply system 23. The supercritical steam 8 flows into the combustor 3 through the light oil fuel supply system 23. By injecting the supercritical steam 8 in which the light fuel 12 remaining in the light oil fuel supply system 23 is dissolved into the combustion gas 16 of the light fuel 12 and the air 4 in the combustor 3, the light fuel 12 is completely discharged. After being burned to the turbine 2, it flows out to the turbine 2. Then, clogging of the light oil fuel supply system 23 is suppressed.

(Third Embodiment) The third embodiment of the present invention will be described below with reference to FIG. In FIG. 5, 1 is a compressor, 2 is a turbine, 3 is a combustor, 4 is air, 5 is high temperature exhaust gas, 6 is an exhaust heat recovery boiler, 7 is water, 8 is supercritical steam, 9 is heavy oil, 10 Is a reformer, 11 is a reformed fuel, 12 is a light fuel,
Reference numeral 16 is a combustion gas, 17 is a reformed fuel supply system, 18 is a heavy oil control valve, 19 is a light oil fuel control valve, 20 is a reformed fuel purge line, 21 and 22 are reformed fuel control valves, and 23 is Light oil fuel supply system, 24 is a supercritical steam control valve for the light oil supply system 25 is an air compressor, 26 is an air supply system, 27
Is air, 28 is a supercritical steam control valve for the reformer, 29 is an air control valve for the light fuel supply system, and 30 is an air control valve for the reformed fuel supply system.

The combustor 3 shown in FIG. 5 has the same structure as that shown in FIG. In this embodiment, the air 4 compressed by the compressor 1 and the light fuel 12 are activated. The turbine 2 is driven by the air 4 and the combustion gas 16 of the light fuel. Exhaust gas 5 after driving the turbine 2 exchanges heat with water 7 in an exhaust heat recovery boiler 6 to generate supercritical steam 8. When the supercritical steam suitable for reforming is obtained, the supercritical steam and the heavy fuel 9 are supplied to the reformer to produce the reformed fuel 11.

Up to a certain partial load operation, the reformed fuel 11
Control valve 2 because the composition of is not suitable for combustion
2 is closed, the control valve 21 is opened, and it is discarded into the purge line 20. When the load increases and the composition of the reformed fuel 11 becomes stable, the control valve 21 is closed, the valve 21 is opened to supply the reformed fuel 11 to the combustor 3, and at the same time the light fuel 12 is controlled by the valve 19. The gas turbine is operated only with the reformed fuel 11. The above is the operation method from start to rating. In this case, as shown in the second embodiment, the valve 24 is opened and the supercritical steam 8
Is supplied to the light oil fuel supply system 23. Supercritical steam 8
After dissolving the remaining light fuel 12 in the supply system 23,
It flows into the combustor 3. Light oil fuel supply system 23
After purging the fuel nozzle 13 for light oil with the supercritical steam 8, the steam control valve 24 is closed. Next, the air compressor 25 is started, the compressed air 27 is supplied to the light fuel supply system 23, and the vapor or drain remaining in the supply system 23 is purged. At that time, the air control valve 30 to the reformed fuel system is closed. After purging, the air compressor 25 is stopped, and the purging operation ends.

On the contrary, when the load decreases, the control valve 19 for the light oil fuel is opened to supply the light fuel 12, and at the same time the control valve 22 for the reformed fuel is closed to the combustor of the reformed fuel 11. Is stopped and the valve 21 is opened to discharge the reformed fuel to the reformed fuel purge line 20. The exhaust heat from the light fuel 12 is used to continuously generate the supercritical steam 8 in the exhaust heat recovery boiler 6. When the supply of the reformed fuel 11 is stopped, the supply of the heavy fuel 9 is stopped and only the supercritical steam 8 is supplied to the reformer 10. The supercritical steam 8 passes straight through the reformer 10 and first sufficiently purges the flow path of the reformed fuel purge line 20.

Then, by closing the control valve 21 and opening the control valve 22, the supercritical steam 8 flows into the combustor 3 via the fuel supply system 17. After the reforming fuel supply system 17 and the reforming fuel nozzle 14 are sufficiently purged with the supercritical steam 8, the steam control valve 28 is closed. Next, the air compressor 25 is started, compressed air 27 is supplied to the reformed fuel supply system 17,
The steam or drain remaining in the supply system 17 is purged. At that time, the air control valve 29 to the light fuel system is closed. After purging, the air compressor 25 is stopped, and the purging operation ends. As a result, the vapor content remaining in each of the flow paths can be purged.

[0031]

According to the present invention, it is possible to suppress clogging of the fuel supply system at the time of switching between reforming fuel and light fuel in a gas turbine that burns heavy fuel reforming fuel.

[Brief description of drawings]

FIG. 1 is a fuel system diagram of a gas turbine according to the present embodiment.

FIG. 2 is a fuel system diagram of a gas turbine.

FIG. 3 is a structural diagram of a combustor according to the present embodiment.

FIG. 4 is a fuel system diagram of the gas turbine according to the present embodiment.

FIG. 5 is a fuel system diagram of the gas turbine according to the present embodiment.

[Explanation of symbols]

1 ... Compressor, 2 ... Turbine, 3 ... Combustor, 4, 27 ... Air, 5 ... High temperature exhaust gas, 6 ... Exhaust heat recovery boiler, 7 ... Water,
8 ... Supercritical steam, 9 ... Heavy oil, 10 ... Reformer, 11 ... Reformed fuel, 12 ... Light fuel, 13 ... Light oil fuel nozzle,
14 ... Fuel nozzle for reforming fuel, 15 ... Swirler, 16
... combustion gas, 17 ... reformed fuel supply system, 18 ... heavy oil control valve, 19 ... light oil fuel control valve, 20 ... reformed fuel purge line 21,22 ... reformed fuel control valve, 23 ... light Oil fuel supply system,
24 ... Supercritical steam control valve for light oil supply system, 25 ... Air compressor, 26 ... Air supply system, 28 ... Supercritical steam control valve for reformer, 29 ... Air control valve for light fuel supply system , 30 ... Air control valve to the reformed fuel supply system.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Akinori Hayashi             2-12-1 Omika-cho, Hitachi-shi, Ibaraki Prefecture             Ceremony Company Hitachi, Ltd. (72) Inventor Shigeyoshi Kobayashi             2-12-1 Omika-cho, Hitachi-shi, Ibaraki Prefecture             Ceremony Company Hitachi, Ltd. (72) Inventor Takashi Ikeguchi             2-12-1 Omika-cho, Hitachi-shi, Ibaraki Prefecture             Ceremony Company Hitachi, Ltd. (72) Inventor Tomohiko Miyamoto             2-12-1 Omika-cho, Hitachi-shi, Ibaraki Prefecture             Ceremony Company Hitachi, Ltd. (72) Inventor Nobuyuki Hokari             2-12-1 Omika-cho, Hitachi-shi, Ibaraki Prefecture             Ceremony Company Hitachi, Ltd. (72) Inventor Hirokazu Takahashi             2-12-1 Omika-cho, Hitachi-shi, Ibaraki Prefecture             Ceremony Company Hitachi, Ltd.

Claims (8)

[Claims] 1. A gas turbine comprising a combustor for switching between a reformed fuel obtained by lightening heavy oil by supercritical steam and a light fuel according to a load, and burning the reformed fuel from the reformed fuel to the light fuel. In the case of switching to the fuel, it has means for supplying supercritical or subcritical steam to the reformed fuel supply system after the supply of the reformed fuel is stopped, and purging heavy fuel remaining in the reformed fuel supply system. A reformed fuel-fired gas turbine characterized by: 2. A gas turbine having a combustor for switching between a reformed fuel obtained by lightening heavy oil by supercritical steam and a light fuel according to a load, and burning the reformed fuel from the light fuel. In the case of switching to fuel, it is characterized by having means for supplying supercritical or subcritical steam to the light fuel supply system after stopping the supply of the light fuel and purging the light fuel remaining in the light fuel supply system. Reformed fuel-fired gas turbine. 3. A combustor having a device for generating supercritical steam and a reformer for lightening heavy oil by the supercritical steam, and combusting the light fuel and the reformed fuel by switching according to load. When switching from reformed fuel to light fuel in a gas turbine that is driven by high-temperature gas from, the supercritical or subcritical fuel is supplied to the reformer and the system that supplies reformed fuel to the combustor after the reformed fuel supply is stopped. A reformed fuel-fired gas turbine, wherein only the critical steam is flowed and the heavy fuel remaining in the reformer and the supply system is purged. 4. The reformed fuel-fired gas turbine according to claim 3, wherein when the light fuel such as light oil is switched to the reformed fuel, the light fuel supply system is supercritical or supercritical after the light fuel supply is stopped. A reformed fuel-fired gas turbine characterized by supplying subcritical steam and purging light fuel remaining in the supply system. 5. The reformed fuel-fired gas turbine according to claim 3 or 4, wherein the reformed fuel supply system and the light fuel supply system are purged with the supercritical or subcritical steam, and then further air or A reformed fuel-fired gas turbine, characterized in that nitrogen is used to purge the drain that is damaged in the supply system. 6. A fuel purge system method for a gas turbine having a combustor for switching between a reformed fuel obtained by lightening heavy oil by supercritical steam and a light fuel according to a load, the method comprising: When switching from a high-quality fuel to the light fuel, supercritical or subcritical steam is supplied to the reformed fuel supply system after the supply of the reformed fuel is stopped, and the heavy fuel remaining in the reformed fuel supply system is purged. A method of purging a fuel system of a reformed fuel-fired gas turbine, the method comprising: 7. A fuel system purging method for a gas turbine equipped with a combustor for switching between a reformed fuel obtained by lightening heavy oil by a supercritical steam in a reformer and a light fuel according to a load. When switching from the reformed fuel to the light fuel, the supercritical or subcritical vapor is supplied to the reformer and the reformed fuel supply system after the supply of the reformed fuel is stopped. A method of purging a fuel system of a reformed fuel-fired gas turbine, characterized in that the heavy fuel remaining in the reformed fuel supply system is purged. 8. A fuel purge system method for a gas turbine having a combustor for switching between a reformed fuel obtained by lightening heavy oil by supercritical steam and a light fuel according to a load, the method comprising: When switching from the fuel to the reformed fuel, supercritical or subcritical vapor is supplied to the light fuel supply system after the supply of the light fuel is stopped, and the light fuel remaining in the light fuel supply system is purged. Method of purging fuel system of reformed fuel-fired gas turbine.