JPS5855332B2 - Purging method and device for dual-fuel firing pressure spray fuel nozzle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for purging a dual-fuel-fired pressure-spray nozzle, and more particularly to a method and apparatus for purging a dual-fuel-fired pressure-spray nozzle used in a combustor of a dual-fuel-fired gas turbine. .

Gas turbines are generally operated by burning liquid fuel, but if they are used in applications where startups and shutdowns are frequent, there is a risk that liquid fuel combustion will not allow rapid startup or rapid increase in output.

For this reason, dual-fuel-burning gas turbines have been manufactured that operate with gaseous fuel during startup or rapid increase in output, and operate with liquid fuel during regular operation.

In this type of gas turbine, a dual-fuel firing nozzle that can inject liquid fuel and gaseous fuel separately is used, but the problem with this nozzle is that when gaseous fuel combustion starts, the liquid fuel in the nozzle If the liquid fuel remaining in the flow path is not purged, the residual liquid fuel will be carbonized by the heat of the gaseous fuel injection flame and the liquid fuel flow path will become clogged.

Therefore, in the past, residual liquid fuel was purged by blowing gaseous fuel into the liquid fuel flow path of the nozzle, such as when starting a gas turbine with gaseous fuel firing or switching from liquid fuel firing to gaseous fuel firing. However, when restarting the gas turbine, unburned gas remains in the high-temperature gas flow path and combustor of the gas turbine from the previous shutdown, so the nozzle must be purged with gaseous fuel at startup. As a result, more fuel is added to the gas turbine and combustor, which lowers the oxygen concentration in the combustor and causes ignition failure.

Furthermore, when the nozzle is purged with gaseous fuel at startup, the pressure of the gaseous fuel is quite high, which causes a problem in that the stability of the flame is disturbed during ignition.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the conventional purge method using gaseous fuel and to provide an improved purge method and apparatus therefor that do not cause ignition failure during start-up.

Embodiments of the present invention will be described below with reference to the accompanying drawings. Prior to this, a piping system and a nozzle structure of a fuel nozzle of a dual-fuel-fired gas turbine will be described.

In FIG. 1, 1 is a combustor of a gas turbine, and 2 is a fuel nozzle attached to the combustor 1.

As shown in FIG. 2, the nozzle 2 has a cylindrical main body 2A, and a liquid fuel pipe 2B is inserted through the center of the two main bodies.

The annular space formed between the outer periphery of the liquid fuel pipe 2B and the inner periphery of the two main bodies is a gaseous fuel flow path 2C, and this flow path 2C is formed by a hole opened in the rear end peripheral surface of the main body 2A. It communicates with the gaseous fuel supply pipe 3 (see FIG. 1) via 2c.

A pressure spray nozzle tip 2D is installed at the tip of the liquid fuel pipe 2B.
is attached, and this nozzle tip 2D is connected to the liquid fuel injection hole 2 of the nozzle cap 2E attached to the tips of the two main bodies.
It is inserted in a.

The nozzle cap 2E also has gaseous fuel injection holes 2b arranged around the liquid fuel injection holes 2a.

The gaseous fuel injection hole 2b communicates only with the gaseous fuel flow path 2C within the two main bodies.

The liquid fuel pipe 2B in the nozzle 2 is connected to a liquid fuel supply pipe 4 as shown in FIG. 6,
A filter 7, a pump 8, and a stop valve 9 are provided and connected to a liquid fuel tank (not shown).

A bypass pipe 4A that bypasses the filter 7 is provided before and after the filter 7, and a differential pressure gauge 1 is installed in this bypass pipe 4A.
8 is provided.

Further, a bypass pipe 4B is provided to bypass the suction side and the discharge side of the pump 8, and a bypass valve 19 and a safety valve 20 are provided in parallel with the bypass pipe 4B.

On the other hand, the gaseous fuel supply pipe 3 includes a manifold 10, a flow rate regulating valve 11. A speed proportional control valve lid stop valve 12 and a strainer 13 are provided.

Further, a vent pipe 21 is branched from the gaseous fuel supply pipe 3 between the valves 11 and 12, and a vent valve 22 is provided therein.

A purge gas fuel supply pipe 14 is branched and connected to the liquid fuel supply pipe 4 from the discharge side of the check valve 5, and this purge gas fuel supply pipe 14 is connected to the manifold 10 on the gas fuel supply pipe 3.
It is connected to the.

The throttle pipe 14 includes a manifold 17 and a filter 15.
, a stop valve 16 is provided.

In the above-mentioned known dual-fuel gas turbine, the valve 16 is opened to supply purge gas when the operation is switched from liquid fuel burning to gaseous fuel burning and when starting up with gaseous fuel burning. Since the fuel is blown into the liquid fuel pipe 2B of the nozzle 2, the residual liquid fuel in the liquid fuel pipe 2B is purged, but in the case of the piping system shown in FIG. Since the pressure was significantly reduced while passing through .12, the difference between the pressure in the combustor 1 and the pressure in the manifold 17 was small, and therefore sufficient purging was not performed.

Therefore, in order to increase the purge pressure and perform a complete purge, an improvement was made in which the purge gas fuel supply pipe 14 was branched from the upstream side of the valve 12 to the gas fuel supply pipe 3, as shown in FIG. However, according to the piping system as shown in Fig. 3, the pressure of the purge gas fuel is too high, contrary to the piping system shown in Fig. Excessive fuel was supplied, causing ignition failure.

(Since a large amount of unburned gas remains in the combustor 1 and the high-temperature gas flow path of the gas turbine from the previous gas turbine shutdown, if gaseous fuel is purged into the combustor 1 when the combustor 1 is restarted, The air ratio within 1 is significantly lower than 1, and as a result,
Ignition failure occurs.

) Also, since the pressure of the purge gas fuel is high, immediately after ignition, the purged gas fuel disturbs the stability of the flame, so there is a risk of misfire.

The present invention was made to solve the problems in the conventional purging method as described above, and FIG. 4 shows an embodiment of a piping system for carrying out the method of the present invention.

(In FIG. 4, the parts indicated by the same reference numerals as in FIG. 3 are the same as the parts shown in FIG. 3, so explanations of these same parts will be omitted.

) In FIG. 4, 23 is a purge conduit, and the purge conduit 23 has one end connected to the liquid fuel supply pipe 4 and the other end connected to the manifold 24.

A check valve 18 is provided as in the conventional example shown in FIG.

One end of the purge gas fuel supply pipe 14 is connected to the manifold 24, and the other end (1) of the purge gas fuel supply pipe 14 is connected to the manifold 24.
It is connected to the gaseous fuel supply pipe 3.

On the other hand, a compressed air supply pipe 25 is connected to the manifold 24, and the throttle pipe 25 is provided with a check valve 26, a stop valve 27, a safety valve 28, a compressor 29, and a filter 30 in this order from the downstream side to the upstream side. ing.

The compressor 29 is connected to a drive device 31, and the drive device 31 is configured to be started only when the gas turbine is started.

Although the compressed air supply pipe 25 is open to the atmosphere at the inlet side of the filter 30, it may be connected to the discharge port of the gas turbine compressor.

Next, the operation of each part of the embodiment of the present invention shown in FIG. 4 will be explained.

(a) When starting the gas turbine from a stationary state.

Before starting, all valves 11, 12, 16, 9, 27 are closed, and valves 19, 20, 22.degree. 28 are also closed.

At startup, first, the drive device 31 of the compressor 29 is activated to drive the compressor 29, and the air sucked into the conduit 25 through the filter 30 is compressed.

Subsequently, the valve 27 is opened, and compressed air is blown into the liquid fuel pipe 2B (see FIG. 2) in the nozzle 2 through the check valve 26, manifold 24, purge line 23, and check valve 18. , residual liquid fuel in the liquid fuel pipe 2B and nozzle tip 2D is purged.

At the same time, the valves 11 and 12 of the gaseous fuel supply pipe 3 are opened by a predetermined opening degree, and the gaseous fuel is passed through the manifold 10 to the nozzle 2.
The gas flows into the gaseous fuel flow path 2c inside, and is blown into the combustor 1 from the gaseous fuel injection hole 2b.

In this case, the gas purged inside the nozzle 2 is not gaseous fuel but compressed air, so even if there is residual gas in the combustor 1, the inside of the combustor 1 will not run out of oxygen, and the The fire becomes easier and the risk of ignition failure is extremely reduced.

In addition, by determining the compression ratio in the compressor 29 and the set openings of the valves 27 and check valves 180, etc., the pressure of the compressed air to be purged is considerably lower than the pressure of the gaseous fuel for combustion. Even after ignition, the nozzle 2 can be purged without disturbing the stability of the flame.

When the purge ends, the drive device 31 of the compressor 29 is stopped, and since the valve 27 is also closed, the check valve 18 is also closed.

(b) When the gas turbine combustor 1 is switched from liquid fuel firing to gas fuel firing.

During liquid fuel burning operation, the valve 9 is in an open state,
Pump 8 is in operation.

On the other hand, the valves 11, 12, 16, 27 are closed and the nozzle 2 is supplied with only liquid fuel.

At the end of the liquid fuel burning operation, the pump 8 is stopped and the supply of liquid fuel to the nozzle 2 is cut off, and at the same time the valve 16 is opened, and the gas fuel supply pipe 3, the purge gas fuel supply pipe 14,
- Gaseous fuel is blown into the liquid fuel pipe 2B inside the nozzle 2 through the manifold 24, the purge pipe 23, and the check valve 18.

Therefore, the liquid fuel pipe 2B in the nozzle 2 and the nozzle tip 2
Residual liquid fuel in D is purged.

Subsequently, the valves 11 and 12 are opened by a predetermined opening degree, and the gaseous fuel passes through the gaseous fuel supply pipe 3 and enters the gaseous fuel flow path 2 of the nozzle 2.
The gas is blown into the gaseous fuel C, and further jetted into the combustor 1 from the gaseous fuel injection hole 2b.

In this case, gaseous fuel is used as the purge gas, but unlike during startup, there is no risk of misfire in the combustor 1, and the stability of the flame is not disturbed.

As described above, according to the present invention, there is an effect that ignition failure does not occur even if the residual fuel in the dual fuel firing pressure spray type fuel nozzle is purged.

[Brief explanation of drawings]

Figure 1 is a fuel nozzle piping system diagram of a conventional dual-fuel gas turbine, Figure 2 is an explanatory diagram showing the fuel nozzle 0 structure of a conventional dual-fuel gas turbine, and Figure 3 is another conventional dual-fuel gas turbine. Piping system diagram of fuel nozzle of combustion gas turbine, No. 4
The figure is a piping system diagram for explaining the purging method and device for the dual-fuel firing pressure spray fuel nozzle according to the present invention. 2... Fuel nozzle, 3... Gaseous fuel supply pipe, 4... Liquid fuel supply pipe, 14...
・Purge gas fuel supply pipe, 16...Valve, 23
... Purge pipe line, 25 ... Compressed air supply pipe, 27 ... Valve.

Claims (1)

[Claims] 1. A liquid fuel flow path for injecting liquid fuel using a pressure spray method, and a gas fuel flow path adjacent to the liquid fuel flow path, and gaseous fuel and liquid fuel are alternately injected. A possible purging method for a dual-fuel firing pressure spray fuel nozzle, the method comprising introducing compressed air into the liquid fuel flow path to purge residual liquid fuel in the liquid fuel flow path when starting gaseous fuel combustion. and a dual-fuel firing pressure spray characterized in that when switching from liquid fuel firing to gaseous fuel firing, residual liquid fuel in the liquid fuel flow path is purged by introducing gaseous fuel into the liquid fuel flow path. How to purge a formula fuel nozzle. 2. A dual-fuel-fired pressure sprayer that has a liquid fuel flow path for injecting liquid fuel using a pressure spray method and a gaseous fuel flow path for injecting gaseous fuel, and is capable of alternately injecting gaseous fuel and liquid fuel. A purge device for a type fuel nozzle, comprising: a purge pipe connected to the liquid fuel flow path; a compressed air supply pipe connected to the purge pipe; and a gaseous fuel supplied to the gaseous fuel flow path. a purge gas fuel supply pipe that connects the purge gas supply pipe to the purge pipe; and a first purge gas fuel supply pipe that is provided in the compressed air supply pipe and is opened when the fuel nozzle is started by burning the gaseous fuel. and a second valve provided in the purge gas fuel supply pipe and opened when the fuel nozzle is switched from a liquid fuel burning state to a gas fuel burning state. Purge device for type fuel nozzle.