JPS6015217B2 - Fuel distribution supply device for combustor - Google Patents

Description

Detailed Description of the Invention The present invention is aimed at reducing nitrogen oxides (N○x) etc. generated in the combustor in a can type combustor such as a gas turbine, and achieving stable combustion over the entire operating range. The present invention relates to a preferred fuel dispensing device.

A conventional fuel distribution and supply system for a multi-can combustor of a gas turbine is constructed as shown in FIG. In the figure,
1 is a compressor, 2 is a combustor, 3 is a turbine, and 50 is a generator. A plurality of combustors 2 (approximately 6 to IZ) are arranged in an annular shape, and one fuel nozzle 4 is provided at one end. In each combustor 2, fuel supplied by a fuel pump 9 provided in a fuel main pipe 7 is equally distributed by a fuel equalizer 8, and a fuel pipe provided corresponding to each fuel pipe is used. 14 and check valve 1
6. Reference numeral 12 denotes a fuel supply V supply controller, which controls the fuel pump 9 by installing the bypass pipe 1Q' and controlling the turn control valve 1 while taking into account the flow rate signal obtained by the fuel flow meter 13. Control the flow rate.

In this conventional device, NOx is first produced in the form of nitrogen monoxide during the combustion process in the combustor 2, which is released into the atmosphere through the turbine 3, combines with oxygen to become nitrogen dioxide, and this reaction In the process, ultraviolet rays and certain hydrocarbons are involved, and peroxides (oxidants) such as ozone are generated secondarily, and when the weather conditions are right, these substances form photochemical smog, which is harmful to the human body. For this reason, NOk'ma is currently attracting attention as a major air pollutant along with sulfur oxides and carbon monoxide.Here, we will discuss in detail the production of nitrogen monoxide during the combustion process mentioned above. Then, the production of nitric oxide is most intense in the stoichiometric combustion region, and decreases in both combustion regions around this, namely, the fuel excess region where there is a lack of combustion air, and the fuel lean region where there is an excess of combustion air. It is known.

Therefore, one of the ways to reduce the amount of nitrogen monoxide produced in the combustor is to use either an excessive fuel combustion method or a lean fuel combustion method. In this case, there is a problem with the generation of combustion air, especially black smoke, caused by a lack of combustion air.On the other hand, the latter method is considered to be the most effective because there is an excess of combustion air, so there is no problem with black smoke generation. Incidentally, a multi-can combustor such as the gas turbine shown in FIG. 1 employs a structure in which each can has one fuel nozzle 4.

With such a single fuel nozzle structure, the air-fuel ratio is large (from about 200 to about 50) from no load to high load.
It is necessary to operate within this wide range of air-fuel ratios. For this reason, for example, if the lean combustion is enabled at high loads, the air-fuel ratio will increase dramatically at low loads,
As a result, there is a problem in that combustion becomes unstable at low loads. In addition, with one fuel nozzle for one combustor, even if an average of excessive combustion air is injected, the air will not flow to the vicinity of the fuel nozzle. Combustion occurs due to the ratio,
Even if the generation of black smoke can be avoided, a large effect on reducing N○× cannot be expected. SUMMARY OF THE INVENTION In view of the drawbacks of the prior art described above, an object of the present invention is to provide a fuel distribution and supply device for a combustor that achieves low NO emissions and stable combustion.

To summarize the most characteristic features of the present invention for achieving this object, a plurality of fuel nozzles are provided in the combustor of a multi-can gas turbine, and a fuel supply system for the fuel nozzle group is connected to one or more fuel nozzles. The structure is such that it is divided into nozzles and the number of combined fuel supply systems during fuel introduction is increased or decreased depending on the amount of fuel.

Next, one embodiment of the present invention will be described with reference to FIG.

First, let me explain about combustor 2.As mentioned above, only one combustor is shown to represent the 6 to 1Z combustors that are actually installed. An inner cylinder 42 is provided, and the annular space 3 formed between them is used as an air circulation part.
This is performed by the compressor i shown in the figure. In the combustor head,
The primary fuel nozzle 4394b and the secondary fuel nozzles 5a, 5b are installed so that the fuel injection holes at the tips face the combustion chamber 44, and the air is can be introduced into the combustion chamber 44.Next, the fuel distribution and supply system connected to this system will be explained, focusing on those added to the system shown in FIG.

The fuel pipes leading from the fuel equalizer 8 to each combustor are branched midway and are connected to primary fuel pipes 14 to primary fuel nozzles 4a and 4b.
A secondary fuel pipe 15 is provided to the secondary fuel nozzles 5a and 5b, and check valves 16 and 17 are provided respectively. Furthermore, the secondary fuel pipe 15 has a controller 2.
A purge air pipe 20 is connected to the air equalizer 19 via a check valve 21. An air main pipe 23 having an air on-off valve 22 operated by a signal from the controller 12 is connected to the air equalizer 19, and pressurized air is supplied from a pressurized air source (not shown) through the air main pipe. is being supplied. In this configuration, when the fuel flow rate is 1/lower than the maximum fuel flow rate, the secondary fuel on-off valve 18 is closed and the air on-off valve 22 is set to the closed state.

As a result, fuel is supplied to the primary fuel nozzles 4a and 4b, and air is supplied to the secondary fuel nozzles 5a and 5b, respectively.
Combustion is performed only through the primary fuel nozzles 4a and 4b, and the secondary fuel nozzles 5a and 5b are cooled with air so as not to reach high temperatures. Moreover, this secondary fuel nozzle 5a,
The air flowing to 5b prevents clogging and corrosion of the flow part. On the other hand, when the fuel flow rate reaches 1/sa, the secondary fuel on-off valve 18 opens in response to a signal from the controller 12, and at the same time the air on-off valve 22 closes, and the secondary fuel nozzles 5a, 5
Combustion by b starts. At this time, the primary fuel nozzle 4
Since the fuel injection pressures of a, 4b and the secondary fuel nozzles 5a, 5b are equal, if the numbers and ports of the primary fuel nozzles and secondary fuel nozzles are equal, the primary fuel pipe 14 and the secondary fuel pipe 15 The fuel flow rates flowing through are equal. As shown in this embodiment, the fuel nozzle provided in the combustor 2 is divided into a plurality of parts and distributed, and excess air is blown into the vicinity of each fuel nozzle.
The actual combustion load becomes smaller, and even if the air-fuel ratio is the same as the conventional one, the actual combustion state approaches lean combustion, and the amount of N○× generated decreases.

Further, as in this embodiment, when the fuel flow rate is less than 1/2, only the primary fuel nozzles 4a and 4b are used, and when it exceeds 1/2, the secondary fuel nozzles 5a and 5b are also used. , the air-fuel ratio per fuel nozzle is 2
The operating range narrows from 00-50 to 200-100,
Since the stability of the fuel is improved and the average lean burn-up can be improved, it is possible to further suppress the generation of gourds. Furthermore, since the fuel supply system is switched for each combustor at the same time, there is no interference between the combustors and stable combustion can be achieved. By the way, in the embodiment shown in FIG. 2, the following points arise.

FIG. 3 shows the pressure changes in the primary fuel pipe 14 and the secondary fuel pipe 15 when the secondary fuel on-off valve 18 and the air on-off valve 22 are operated simultaneously in the fuel distribution and supply system shown in FIG. This is especially true when the secondary fuel pipe (air) is operated at a low pressure compared to the primary fuel pipe (fuel). As shown in FIG. 3, when the secondary fuel on-off valve 18 and the air on-off valve 22 operate, air supply to the secondary fuel pipe 15 is stopped and fuel supply is started instead. The pressure increases towards a point of equilibrium with the primary fuel pipe 14. On the other hand, the pressure in the primary fuel pipe 14 is
The fuel supply to 5 causes a rapid descent. Here, the pressure difference between the primary fuel pipe 14 and the secondary fuel pipe 15 before the operation of the secondary fuel on-off valve 18 and the air on-off valve 22 is ΔP, and during the maximum pressure fluctuation of the primary fuel pipe 14 after the operation. Let △P2 be △P,
As ΔP2 increases, ΔP2 increases. This will rapidly reduce the injection pressure of the fuel nozzles 4a and 4b during combustion, which will have a large impact on combustion and may cause blow-out. On the other hand, in order to prevent this blowout, if the secondary fuel pipe 15 (air) is set to a higher pressure than the primary fuel pipe 14 (fuel), the secondary fuel on-off valve 18 and the air on-off valve 22 The effect on combustion due to the operation of is reduced, but when the fuel flow rate is less than 1/milk, a large amount of high pressure air flows, so there is a problem that the power cost of the pressurized air source increases. In order to solve this problem, the pressure difference between the primary fuel pipe 14 (fuel) and the secondary fuel pipe 15 (air) is made small, and the pressures of both are made to follow, and the secondary fuel on-off valve 18 In the embodiments shown in FIGS. 5 and 6, the pressure changes after the operation of the air on-off valve 22 are made as shown in FIG. 4.

First, the embodiment shown in FIG. 5 will be explained.

In FIG. 5, the same reference numerals as in FIG. 2 indicate the same parts, so the explanation thereof will be omitted here. The difference from the one in FIG. 2 is that pressure discharge pipes 24 and 25 take out fuel pressure and air pressure from the fuel equalizer 8 and the air equalizer 19, respectively.
is connected to a differential pressure transmitter 26 that generates a differential pressure signal, and the signal from the differential pressure transmitter 26 is guided to a controller 27, and the signal from the controller 27 controls the pressure adjustment provided in the air main pipe 23. The valve 28 is operated. In this embodiment, for example, the fuel equalizer 8
If the pressure increases, control.

- The differential pressure between the fuel equalizer 8 and the air equalizer 19 increases with respect to the differential pressure setting value of the pressure regulator valve 27.
opens and the pressure in the air equalizer 19 increases. That is,
The pressure regulating valve 28 operates so that the pressure in the air equalizer 19 follows the pressure change in the fuel equalizer 8, and the differential pressure between the fuel equalizer 8 and the air equalizer 19 is always constant. The differential pressure is
It can be arbitrarily selected by changing the set value of the controller 27. Primary fuel pipe 14 (fuel) and secondary fuel pipe 1
5 (air) are respectively connected to the equal dividers 8 and 19, so as a result of the pressure control described above, it is possible to minimize the pressure difference between the fuel pipes 14 and 15 as shown in FIG. Even if the secondary fuel on-off valve 18 and the air on-off valve 22 operate, the sudden and fluctuating large pressure change in the primary fuel pipe 14 (fuel) as shown in FIG. 3 does not occur, and combustion starts. This has the effect of reducing the influence of

Also, the pressure of the secondary fuel pipe 15 (air) is changed to the primary fuel pipe 14.
(fuel) pressure, compared to the case where the pressure of the secondary fuel pipe is set high and constant to solve the blowout problem, there is no need to flow excessive air, and the pressure of the pressurized air source is This has the effect of reducing power costs and making it compatible with fully automated driving. Next, the embodiment shown in FIG. 6 will be explained. The difference between this embodiment and the embodiment shown in FIG. Pressurized air source 2
It is located where it leads to 9.

That is, in this embodiment, the pressurized air valve 29 is, for example, one with a variable rotation speed, and the amount of discharged air is changed by controlling the rotation speed, whereby the secondary fuel pipe 1
5 (air) pressure is ensured. According to this embodiment, the same effects as the embodiment shown in FIG. 5 can be achieved, and since the pressurized air source 29 is operated to discharge only the required amount of air, operating costs can be saved. It has the advantage of being wet. In the above explanation, we have taken up an example in which multiple fuel nozzles are divided into two fuel supply systems, primary and secondary, but this can be divided into three or more systems to supply fuel according to the fuel flow rate. A fuel distribution and supply system that increases or decreases the number of systems can also be realized by the present invention.

FIG. 7 shows an example of this, and is an example in which three fuel supply systems are used. In this case, the combustor 2 is provided with a tertiary fuel nozzle 31 in addition to the primary and secondary fuel nozzles 4 and 5, and the tertiary fuel nozzle 31 has a tertiary fuel nozzle 31 newly added to the configuration shown in FIG. A secondary fuel pipe 30 is connected, and a tertiary fuel opening/closing valve 32 and a check valve 33 are provided in the middle, and the air main pipe 2
3, a purge air pipe 37 is newly provided which is extended via an air on-off valve 34, an air equalizer 35, and a check valve 36, and is connected to the tertiary fuel pipe 30.
Further, the tertiary fuel on-off valve 32 and the air on-off valve 34 are both operated by a signal from the controller 12, and the pressure take-off pipe 25 on the air side is connected to an air equalizer 35 attached to the new one.
Install and configure. Here, the controller 12 controls the secondary fuel on-off valve 1 when the fuel flow rate is 1/3 or more of the maximum fuel flow rate.
8 and the air on-off valve 22, respectively, and the tertiary on-off valve 32 and the air on-off valve 34 in the case of 2'3 and above are configured to issue a close signal. Therefore, when the fuel flow rate reaches 1'3, the secondary fuel on-off valve 18 opens and the air on-off valve 22 closes, and then when the fuel flow reaches 2'3, the tertiary fuel on-off valve 32 opens.
opens, and the air on/off valve 34 closes.

During this time, since the pressure regulating valve 28 is operating, sudden and large pressure changes in the fuel pipes 14, 15, and 30 do not occur, and each valve can be opened and closed smoothly. In short, if the piping and the like are sequentially increased in the manner newly added in this embodiment, it is possible to create a fuel distribution and supply system divided into three or more fuel supply systems.

The content of the present invention has been described in detail above, but the most characteristic feature of the present invention is that a plurality of fuel nozzles are provided in the combustor of a multi-can gas turbine, and a fuel supply system for the fuel nozzle group is connected to one or more fuel nozzles. A fuel equalizer is installed that divides the fuel into multiple fuel nozzles and increases or decreases the fuel supply system that introduces fuel according to the amount of fuel, and equally divides the fuel flow rate supplied to each can for each can. The fuel supply system is divided into fuel supply systems corresponding to each can of the nuclear fuel equalizer, and the fuel supply system of each can is configured to operate simultaneously, and the fuel nozzle and the fuel nozzle to which fuel is not supplied are divided. A purge air supply system is installed to supply purge air to the fuel piping, which not only reduces the combustion load per fuel nozzle but also narrows the operating range of the air-fuel ratio. , NOx generation amount is reduced, and combustion stability is achieved.

[Brief explanation of drawings]

Fig. 1 is a system diagram showing a conventional fuel supply system having a multi-can combustor, Fig. 2 is a system diagram showing an embodiment of the fuel distribution and supply system according to the present invention, and Fig. 3 is the system shown in Fig. 2. FIG. 4 is an explanatory diagram of ideal fuel pipe pressure fluctuations, and FIGS. 5 to 7 are system diagrams showing other embodiments of the present invention. 2... Combustor, 4, 4a, 4b...1
Secondary fuel/nozzle, 5, 5a, 5b... Secondary fuel nozzle, 7... Fuel main tube, 8... Fuel equalizer, 9...・Fuel pump, 11...Return control valve, 12...Controller, 14...
...Primary fuel pipe, 15...Secondary fuel pipe, 18...
...Secondary fuel on/off valve, 19,35...Air equalizer, 20,37...Page air pipe, 22,
34... Air on-off valve, 23... Air main pipe,
26...Differential pressure transmitter, 27...Controller, 28...Pressure control valve, 29...
- Pressurized air source. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Scope of Claims] 1. A plurality of fuel nozzles are provided in the combustor of a multi-can gas turbine, and a fuel supply system for the fuel nozzle group is divided into one or more fuel nozzles, and the fuel supply system is divided according to the amount of fuel. The fuel supply system for introducing fuel is configured to increase or decrease depending on the amount of fuel, and a fuel equalizer is provided to equally divide the fuel flow rate supplied to each can corresponding to each can, and the fuel equalizer is configured to correspond to each can. Purge air is configured such that the fuel supply system is divided into fuel supply systems for each can, and the fuel supply systems for each can are operated simultaneously, and purge air is supplied to fuel nozzles and fuel pipes to which fuel is not supplied. A fuel distribution and supply device for a combustor, characterized in that a supply system is provided. 2. In claim 1, the purge air supply system is provided with a purge air pressure control device that causes the pressure on the fuel pipe side during purge air introduction to follow the pressure on the fuel pipe side during fuel introduction. A fuel distribution and supply device for a combustor, characterized by: 3. In claim 2, the purge air pressure control device includes means for detecting a pressure difference between the fuel pipe side during fuel introduction and the fuel pipe side during purge air introduction, and an output of the pressure difference detection means. 1. A fuel distribution and supply device for a combustor, comprising a pressure control valve that controls purge air supply pressure in response to a signal. 4. In claim 2, the purge air pressure control device includes means for detecting a pressure difference between the fuel pipe side during fuel introduction and the fuel pipe side during purge air introduction, and an output signal of the pressure detection means. A fuel distribution and supply system for a combustor, which is characterized by comprising a pressurized air source controlled by a combustor.