JP2014031777A - Gas turbine combustor and fuel supply method for gas turbine combustor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas turbine combustor which uses both bioethanol and liquid fossil fuel such as light oil as fuel, and has a constitution switching a fuel system from one system to a plurality of systems, the gas turbine combustor being capable of reducing the discharge amounts of smoke and of soot and dust produced when the system is switched and preventing unstable combustion.SOLUTION: The gas turbine combustor includes: a pressure spraying type liquid fuel nozzle 11 and a fuel system 101 which supply liquid fossil fuel such as bioethanol and light oil; a diffusion combustion burner which mixes the fuel and compressed air 200; and a water injection nozzle 13 and a water injection system 103 which injects water into the combustor so as to reduce nitrogen oxides. A part of the fuel is supplied to the water injection system 103 on the condition that a fuel flow rate is equal to or larger than a predetermined value.

Description

  The present invention relates to a gas turbine combustor.

  In recent years, in gas turbine combustors, there is an increasing need for using various fuels in addition to fossil fuels such as natural gas and light oil. In particular, from the viewpoint of suppressing global warming and reducing carbon dioxide emissions, there has been an active movement to use bioethanol purified from plants as fuel for gas turbines. Bioethanol is more expensive than liquid fossil fuels such as kerosene and light oil, and there is a problem in the stable procurement of fuel. For this reason, the demand for the gas turbine combustor corresponding to both bioethanol and liquid fossil fuel is increasing.

  In order to improve the efficiency of gas turbines and reduce costs, pressure spray type fuel nozzles are widely used as fuel nozzles for liquid fuel. The pressure spray type fuel nozzle does not require a medium such as atomizing air for atomizing the fuel, so that an auxiliary facility such as an atomizing air compressor is not required, and there is an advantage that initial cost and running cost can be reduced.

  Since bioethanol has a lower calorific value per unit volume than liquid fossil fuel, in order to obtain the same output, it is necessary to supply a larger amount of bioethanol to the gas turbine than liquid fossil fuel. When fuels with different calorific values, such as bioethanol and light oil, are sprayed with the same fuel nozzle, the ratio between the maximum flow rate and the minimum flow rate of the fuel increases. When a pressure spray type fuel nozzle is designed according to the maximum flow rate of bioethanol, the differential pressure between the fuel supply pressure and the combustor internal pressure is reduced under the minimum flow rate condition of light oil. For this reason, the atomization characteristics are lowered, the amount of smoke and dust discharged increases, and combustion may become unstable. On the other hand, if the fuel nozzle is designed in accordance with the maximum flow rate of light oil burning, the differential pressure required to supply the maximum flow rate of bioethanol increases. For this reason, the specifications of the fuel supply system such as the fuel pump and the fuel pipe must correspond to the high pressure, which may increase the cost of the fuel system.

  Patent Document 1 discloses a fuel supply structure for suppressing combustion instability and fuel system cost increase when two types of fuels having different calorific values are used in a gas turbine combustor.

JP-A-7-224688

  In Patent Document 1, a plurality of fuel supply systems are provided. When the fuel flow rate is low, fuel is supplied from one system, and when the fuel flow rate is increased, fuel is supplied from the other system together with the above-described system. A method for reducing the flow rate ratio and stabilizing combustion is disclosed. When this method is used, when the fuel system is switched from one system to a plurality of systems, the nozzle hole area of the fuel nozzle increases and the differential pressure in the fuel nozzle temporarily decreases. For this reason, atomization characteristics deteriorated, and there was a possibility that the amount of smoke and dust discharged increased. In addition, since a plurality of fuel systems are installed, there is a problem that costs increase.

  The object of the present invention is to suppress smoke and dust emission in any gas turbine combustor that uses hydrophilic fuel with low calorific value and fuel with high calorific value as fuel. The object is to provide a gas turbine combustor capable of stable combustion.

  The gas turbine combustor of the present invention is a gas turbine combustor capable of burning a plurality of fuels having different calorific values, a combustion chamber for burning fuel and air, a liquid fuel nozzle for injecting liquid fuel into the combustion chamber, A liquid fuel system capable of supplying the liquid fuel nozzle with a first liquid fuel and a hydrophilic second liquid fuel having a lower calorific value per unit volume than the first fuel; and water in the combustion chamber. A first water injection nozzle for injecting, a first water injection system for supplying water to the first water injection nozzle, and a flow rate of the liquid fuel flowing down the liquid fuel system, the flow rate of the first liquid fuel being A first branch pipe for branching a part of the liquid fuel flowing down the liquid fuel system to the first water injection system under a condition equal to or greater than a predetermined amount determined in a range larger than a fuel flow rate in a rated load condition; It is characterized by having To.

In a gas turbine combustor that uses a hydrophilic fuel with a low calorific value and a fuel with a high calorific value as a fuel, regardless of which fuel is used, the gas turbine combustion is capable of stable combustion with reduced smoke and dust emission Can be provided.

The block diagram which shows the structure of the gas turbine in 1st Example of this invention. The figure which shows the relationship between the liquid fuel pressure and liquid fuel flow volume in 1st Example of this invention. The figure which shows the relationship between the liquid fuel pressure and liquid fuel flow volume of the conventional structure in one fuel system. The figure which shows the relationship between the liquid fuel pressure of the conventional structure and liquid fuel flow volume in two fuel systems. The figure which shows an example of the relationship between the gas turbine load in 2nd Example of this invention, and the flow volume of the water which flows through a water injection system, and bioethanol. The figure which shows the relationship between the water mixing ratio of ethanol, and the combustion temperature when carrying out diffusion combustion. The figure which shows the relationship between the gas turbine load in 2nd Example of this invention, and the flow volume of the water which flows through a water injection system, and bioethanol. The block diagram which shows the type | system | group of the gas turbine in 3rd Example of this invention. The figure which shows the relationship between the fuel pressure of the fossil fuel and fuel flow in 3rd Example of this invention. The figure which shows an example of the relationship of the flow volume of the gas turbine load in the 3rd Example of this invention, the water which flows through a water injection system, and a liquid fossil fuel. The figure which shows the relationship between the fuel pressure and fuel flow volume of bioethanol in 3rd Example of this invention. The figure which shows an example of the relationship between the gas turbine load in 3rd Example of this invention, and the flow volume of the water and bioethanol which flow through a water injection system.

  Hereinafter, examples will be described with reference to the drawings.

  A gas turbine combustor according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 2.

  FIG. 1 shows an overall view of a gas turbine according to the present invention. The power generation gas turbine includes a compressor 1, a combustor 2, and a turbine 3, and the generator 4 is driven by the turbine 3 to obtain electric power. The combustor 2 is disposed downstream of the diffuser 5 serving as a flow path for the compressed air 200 compressed by the compressor 1. The combustor 2 includes an outer cylinder 6 that stores main components, an inner cylinder 7 that burns fuel to generate combustion gas 204, and an upstream end of the combustor so as to seal an upstream end of the outer cylinder 6. And an end cover 8 installed in the section, and a transition piece 9 connected to the downstream side of the inner cylinder 7 and guiding the combustion gas to the turbine. Inside the inner cylinder 7 is a combustion chamber 300 for burning fuel and air. A swirler 10 is disposed on the upstream side of the inner cylinder 7, and a liquid fuel nozzle 11 for injecting liquid fuel into the combustion chamber is provided at the center of the shaft. A gas fuel nozzle 12 is provided on the upstream side of the swirler 10, and a water injection nozzle 13 is provided on the end cover 8.

  In this embodiment, the liquid fuel nozzle 11 is a pressure spray type fuel nozzle. The pressure spray type fuel nozzle is a system in which liquid fuel is injected into a liquid film and atomized by the pressure difference between the liquid fuel pressure and the combustor 2 internal pressure. Since the pressure spray type fuel nozzle does not require a medium such as atomizing air for atomization, an incidental facility such as an atomizing air compressor becomes unnecessary, and there is an advantage that initial cost and running cost can be reduced.

  A liquid fuel system 101 is connected to the liquid fuel nozzle 11, a gaseous fuel system 102 is connected to the gaseous fuel nozzle 12, and a water injection system 103 is connected to the water injection nozzle 13. The liquid fuel system 101 includes a fuel tank 14 for storing bioethanol, a fuel tank 15 for storing liquid fossil fuel such as kerosene and light oil, a fuel pump 17, a flow control valve 18a, and a cutoff valve 19a. The gaseous fuel system 102 includes a gaseous fuel tank 16, a vaporizer 20, a flow control valve 18b, and a shutoff valve 19b. The water injection system 103 includes a water tank 21, a water pump 22, a flow rate adjusting valve 18c, a shutoff valve 19c, and a check valve 23b for storing water to be injected into the combustion chamber 300. The feature of this embodiment is that the liquid fuel system 101 is branched downstream of the shutoff valve 19a, one end is connected to the liquid fuel nozzle 11, and the other is connected to the water injection system 103 via a check valve 23a as a branch pipe. It is.

  In this embodiment, the compressed air 200 compressed by the compressor 1 flows into the combustion chamber 300 through the diffuser 5 and passes between the outer cylinder 6 and the inner cylinder 7. A part of the compressed air 200 flows into the combustion chamber 300 as the cooling air 201 of the inner cylinder 7. The compressed air 200 other than the cooling air 201 passes through the swirler 10 to become a swirling flow and flows into the inner cylinder 7. The compressed air 200 that has passed through the swirler 10 is mixed with the liquid fuel injected from the liquid fuel nozzle 11 or the gaseous fuel supplied from the gaseous fuel nozzle 12 to form a diffusion flame 203 in the combustion chamber 300.

  The combustion gas 204 generated by the diffusion flame 203 passes through the transition piece 9 installed downstream of the combustor 2 and flows into the turbine 3. The combustion gas 204 is exhausted through an exhaust duct after driving the turbine 3 and the generator 4. In the case of diffusion combustion as in the present invention, the combustion gas 204 becomes high temperature under a high load condition of the gas turbine, and the emission amount of nitrogen oxide increases exponentially as the temperature rises. Therefore, under high load conditions, water is injected from the water injection nozzle 13 toward the inner cylinder 7 to reduce the local high temperature region of the diffusion flame 203, thereby reducing the discharge amount of nitrogen oxides.

  The check valve 23a closes the flow path inside the valve by the elastic force of the spring, and the flow path is closed and set when the difference between the fuel supply pressure of the liquid fuel system 101 and the pressure of the combustion chamber 300 is less than a set value. When it becomes higher than the value, the flow path is opened and the fuel starts to flow through the check valve 23a. Hereinafter, the set value of the check valve 23a is referred to as a crack pressure.

  Next, the operation of the liquid fuel system 101, the water injection system 103, and the check valve 23a when using liquid fuel in the gas turbine configured as described above will be described with reference to FIG. 1 and FIG. In FIG. 2, the horizontal axis indicates the pressure of the liquid fuel, and the vertical axis indicates the liquid fuel flow rate. 2 indicate the fuel flow rate under the rated load conditions of liquid fossil fuel and bioethanol, and the minimum fuel flow rate during the combustion of liquid fossil fuel. Bioethanol has a lower calorific value than liquid fossil fuels such as kerosene and light oil, and the fuel flow rate is higher than that of liquid fossil fuels to obtain the same gas turbine load.

  In the case of liquid fossil fuel, the liquid fuel pressure at the rated fuel flow is less than the crack pressure of the check valve 23a. On the other hand, in the case of bioethanol, the flow rate increases compared to the liquid fossil fuel, so the liquid fuel pressure at the rated fuel flow rate becomes equal to or higher than the crack pressure of the check valve 23a. When the liquid fuel pressure becomes equal to or higher than the crack pressure of the check valve 23a, a part of the liquid fuel branches to the water injection system 103 via the branch pipe and is supplied from the water injection nozzle 13 to the combustion chamber 300 through the water injection system 103. For this reason, the fuel flow rate with respect to the liquid fuel pressure rapidly increases.

  FIG. 3 shows an example of the relationship between the fuel pressure and the fuel flow rate in the case of one conventional fuel system. When spraying bioethanol and liquid fossil fuel in one fuel system as shown in FIG. 3, the maximum flow rate is at the rated load of bioethanol burning, and the minimum flow rate is at the start of liquid fossil fuel burning. In such a gas turbine, the ratio between the maximum flow rate and the minimum flow rate of the fuel is larger than that of the gas turbine exclusively for bioethanol or liquid fossil fuel. For this reason, when the fuel nozzle and the system are designed according to the maximum flow rate of bioethanol burning, the differential pressure between the fuel supply pressure and the pressure of the combustion chamber 300 becomes small at the minimum flow rate of liquid fossil fuel burning.

  In the case of a pressure spray type fuel nozzle, if the differential pressure is low, the atomization characteristics may be reduced and the amount of dust emission may be increased. In addition, if the fuel nozzle and system are designed for the maximum flow rate of liquid fossil fuel, the fuel differential pressure required to supply fuel under the rated load conditions of bioethanol is extremely large, and a high-pressure pump is required. Become. Moreover, there is a problem that the cost of the fuel system increases when the fuel pump and the fuel pipe are changed to the high pressure specification. Furthermore, if the differential pressure of the fuel at the rated load condition becomes too large, the fuel spray characteristics change, and the fuel spray collides with the parts constituting the combustor 2 and the metal temperature of the parts rises. May change.

  In this embodiment, as shown in FIG. 2, the fuel flow rate at the crack pressure of the check valve 23a is set to a predetermined amount or more determined in a range larger than the fuel flow rate under the rated load condition of the liquid fossil fuel, and the fuel flow rate becomes the crack pressure or more Is supplied to the water injection system. With this configuration, when the liquid fossil fuel is burned, fuel is injected only by the liquid fuel nozzle 11 from the start of the gas turbine to the rated load condition.

  At this time, the specification of the liquid fuel nozzle 11 can be designed in accordance with the liquid fossil fuel, and the liquid fossil fuel can be sufficiently atomized even under conditions where the fuel flow is small and the differential pressure is small, such as when the liquid fossil fuel is started up. Can be suppressed. Furthermore, since the supply pressure of the liquid fossil fuel can be set to a desired pressure even under rated load conditions, the atomization characteristics of the liquid fossil fuel can be maintained in a good state, and smoke and dust emission can be suppressed.

  Further, when the bioethanol is burned, the fuel supply pressure becomes equal to or higher than the crack pressure of the check valve 23a under the partial load condition of the gas turbine. For this reason, a part of bioethanol can be supplied to the combustion chamber 300 through the water injection system 103, and even if the fuel has a low calorific value and a large fuel flow rate under the rated load conditions, such as bioethanol, an excessive increase in the differential pressure of the fuel is prevented. it can. In this way, it is possible to suppress an excessive increase in the fuel supply pressure during bioethanol burning, while maintaining a fine atomization characteristic during the burning of liquid fossil fuel. For this reason, the spray characteristics do not change greatly even under the rated load conditions when burning bioethanol, and the fuel spray does not collide with the parts constituting the combustor 2, so that the metal temperature of the parts does not rise.

  Moreover, when supplying spray water from the water injection system | strain 103, it mixes with bioethanol and injects. In this case, bioethanol is a hydrophilic fuel and is easily mixed with water even when supplied to the water injection system 103. For this reason, fuel and water are supplied from the water injection nozzle 13 to the combustion chamber 300 without being separated, and combustion instability does not occur.

  In this embodiment, when the fuel supply pressure of bioethanol becomes equal to or higher than the crack pressure of the check valve 23 a, a part of bioethanol is supplied to the combustion chamber 300 through the water injection system 103. For this reason, the flow rate of the fuel supplied from the liquid fuel nozzle 11 to the diffusion flame 203 is reduced. By supplying bioethanol to the liquid fuel nozzle 11 and the water injection nozzle 13 in a distributed manner, the local flame temperature of the diffusion flame 203 formed in the vicinity of the liquid fuel nozzle 11 is lowered, and the amount of nitrogen oxides discharged is reduced. To reduce.

  Further, bioethanol supplied from the water injection nozzle 13 is injected in a state of being mixed with water, evaporates with the spray water in the inner cylinder 7 and burns. Since the flame temperature of the diffusion flame 203 is reduced by the heat of vaporization when the spray water evaporates, the discharge amount of nitrogen oxide is further reduced. In addition to the flame temperature being lowered due to the evaporation of the spray water, the generated steam lowers the local oxygen concentration and slows the combustion reaction. For this reason, the diffusion flame 203 becomes longer, heat loss to the surroundings increases, and the flame temperature of the diffusion flame 203 further decreases. Thereby, the discharge | emission amount of a nitrogen oxide can further be reduced and the metal temperature of the components which comprise the combustor 2 can be reduced.

As described above, in a combustor equipped with a system that supplies bioethanol to the water injection system and a check valve in which the crack pressure is set to be equal to or higher than the rated load flow rate condition of liquid fossil fuel, bioethanol is dispersed. Thus, the combustion reaction is slowed down by the spray water, so that the emission amount of nitrogen oxides can be reduced as compared with the conventional example. For this reason, since the water injection flow rate required in order to make the discharge | emission amount of nitrogen oxide below an environmental regulation value reduces, the efficiency of a gas turbine can be improved. In addition, even when supplying liquid fossil fuel, the atomization characteristics are not impaired, so that it is possible to suppress an increase in the amount of discharged dust.

  A gas turbine combustor and a water injection control method according to a second embodiment of the present invention will be described with reference to FIGS.

  FIG. 4 shows an overall view of a gas turbine according to a second embodiment of the present invention. In the present embodiment, in addition to the configuration of the first embodiment, a fuel flow meter 24 is installed in a fuel pipe that branches from the fuel system 101 to the water injection system 103, and a water flow meter 25 is installed in the water injection system 103. 24 and a control device 26 for controlling the flow rate of water flowing through the water injection system 103 by calculating a set value of the water flow rate from the indicated values of the water flow meter 25.

  In a diffusion combustion type gas turbine combustor, when water is injected into the combustor to reduce NOx, there is a method of controlling the flow rate of water so as to be a constant ratio with respect to the fuel flow rate. FIG. 5 shows the flow rates of bioethanol and water flowing through the fuel system 101 and the water injection system 103 when the flow rate of water is controlled to be a constant ratio with respect to the gas turbine load in the second embodiment. . The horizontal axis in FIG. 5 is the gas turbine load, and the vertical axis is the flow rate of bioethanol and water.

  Water starts to be supplied from the low load condition of the gas turbine, and the flow rate gradually increases as the load increases. When the load increases and the fuel supply pressure of bioethanol becomes equal to or higher than the crack pressure of the check valve 23 a, bioethanol begins to flow into the water injection system 103. Since the flow rate of bioethanol flowing through the water injection system 103 increases under a high load condition, the ratio of bioethanol flowing through the water injection system 103 increases when the water flow rate setting value is small. In this case, there is a possibility that the diffusion flame 205 is formed downstream of the water injection nozzle 13.

  FIG. 6 shows an example of the relationship between the mixing ratio of ethanol and water and the combustion temperature when the mixed fuel is subjected to diffusion combustion. The horizontal axis in FIG. 6 indicates the mixing ratio of ethanol in the mixed fuel, and the vertical axis indicates the combustion temperature. It can be seen that the combustion temperature rises as the ethanol mixing ratio increases, and that the combustion temperature becomes 1800 K or more at an ethanol mixing ratio of 35% or more. When the combustion temperature is 1800K or higher, the increase in nitrogen oxides, so-called thermal NOx, produced by the reaction of nitrogen and oxygen in the air becomes significant. When the bioethanol mixing ratio in the mixed fluid supplied from the water injection nozzle 13 increases, the combustion temperature of the diffusion flame 205 becomes 1800K or more, and the discharge amount of thermal NOx may increase.

Therefore, in the present embodiment, the ratio of bioethanol flowing through the water injection system 103 from the indicated values of the liquid fuel flow meter 24 and the water flow meter 25 is (Equation 1).
m _b / (m _w + m _b ) * 100 ≦ 35 * α (Formula 1)
m _b : Bioethanol flow rate m _w : Water flow rate α: A control device 26 that controls the flow rate of water so as to have a coefficient is provided. Here, the coefficient α is a positive value smaller than 1, and is preferably set appropriately in consideration of the difference in calorific value between ethanol and bioethanol and the environmental regulation value.

  FIG. 7 shows the relationship between the gas turbine load and the bioethanol flowing through the water injection system and the water flow rate in this embodiment. Under low load conditions, the water flow rate gradually increases with increasing load. When the load increases and the fuel supply pressure of bioethanol becomes equal to or higher than the crack pressure of the check valve 23 a, bioethanol begins to flow into the water injection system 103. When the load further increases and the flow rate of bioethanol flowing through the water injection system 103 increases, the water flow rate is controlled by the control device 26 and the flow rate of water flowing through the water injection system 103 is increased. Thus, by adjusting the flow rate of water flowing through the water injection system 103 so as to be proportional to the flow rate of bioethanol flowing through the water injection system 103, the mixing ratio of the bioethanol flowing through the water injection system 103 is kept below a set value. To do.

  By controlling the water flow rate as in this embodiment, the combustion temperature of the diffusion flame 205 formed downstream of the water injection nozzle 13 can be suppressed to less than 1800K, and thermal NOx can be reduced. In the present embodiment, the water flow rate may increase as compared to the first embodiment because the bioethanol mixing ratio of the water injection system 103 is kept below the set value under high load conditions. Since the flow rate of the combustion gas 204 increases due to the increase in the water flow rate, the effect of increasing the output of the gas turbine can be obtained.

  On the other hand, in the conventional example, when the flow rate of water injected from the water injection nozzle 13 increases, the temperature of the diffusion flame 203 decreases, the combustion reaction becomes slow, the combustion efficiency decreases, and the gas turbine efficiency can decrease. There was sex. On the other hand, in this embodiment, bioethanol is injected together with water from the water injection nozzle 13 and burned, so that the temperature of the diffusion flame 203 does not drop significantly even if the water flow rate increases, and the combustion efficiency is lowered. Can be prevented.

  Thus, in this embodiment, thermal NOx can be reduced by controlling the water flow rate in accordance with the flow rate of bioethanol flowing through the water injection system. Further, since the water flow rate is increased as compared with the conventional example, the output of the gas turbine can be increased. Furthermore, it is possible to prevent a decrease in combustion efficiency even when the water injection amount is increased.

  In addition, although a present Example is a structure which controls using the instruction | indication value of the water flow meter 25 installed in the water injection system | strain 103, it uses the water flow rate calculated from the valve opening degree of the flow control valve 18c as an instruction | indication value. May be.

  A gas turbine combustor according to a third embodiment of the present invention will be described with reference to FIGS. The basic configuration of this embodiment is the same as that of the first example. This embodiment can improve the ignition characteristics of liquid fossil fuel and bioethanol.

  FIG. 8 shows a system diagram of the gas turbine combustor in the present embodiment. The fuel nozzle 11 of the present embodiment has a double tubular tip, and injects liquid fuel from two systems of a pilot fuel injection hole 27 provided at the center and a main fuel injection hole 28 provided on the outer periphery thereof. The liquid fuel system 101 includes a fuel tank 14 for storing bioethanol, a fuel tank 15 for storing liquid fossil fuel such as kerosene and light oil, a fuel pump 17, a flow control valve 18a, and a cutoff valve 19a. The liquid fuel system 101 branches to the pilot fuel system 104a and the main fuel system 105a downstream of the shutoff valve 19a. The pilot fuel system 104a further branches to the pilot fuel systems 104b and 104c on the downstream side.

  The pilot fuel system 104 b is connected to the pilot fuel injection hole 27 of the fuel nozzle 11. The pilot fuel system 104c is connected to the water injection system 106 via the check valve 37a and the electromagnetic valve 33. A check valve 37b is arranged in the main fuel system 105a and branches to the main fuel systems 105b and 105c downstream of the check valve 37b. The main fuel system 105 b is connected to the main fuel injection hole 28 of the fuel nozzle 11. The main fuel system 105c is connected to the water injection system 107 via a check valve 37c. Three types of check valves 37a, 37b and 37c are arranged in the fuel system of this embodiment. The crack pressures of these three types of check valves are set higher in the order of 37a <37b <37c.

  Next, the fuel flow in the fuel system configured as described above will be described. Under conditions where the fuel flow rate is low and the fuel supply pressure is less than the crack pressure of the check valve 37a, the fuel flows through the pilot fuel systems 104a to 104b and is supplied from the pilot fuel injection holes 27 to the combustion chamber 300. Under the condition that the fuel supply pressure is not less than the crack pressure of the check valve 37a and less than the crack pressure of the check valve 37b, the fuel flows through the pilot fuel systems 104a to 104b and 104c. The fuel that has flowed into the pilot fuel system 104 b is supplied to the combustion chamber 300 from the pilot fuel injection hole 27. The fuel that has flowed into the pilot fuel system 104c flows through the water injection system 106 when the solenoid valve 33 is open, and is supplied to the combustor 2 from the water injection nozzle 13a.

  Under the condition that the fuel supply pressure is not less than the crack pressure of the check valve 37b and less than the crack pressure of the check valve 37c, the fuel is supplied to the pilot fuel systems 104a, 104b, 104c and the main fuel systems 105a, 105b. The fuel that has flowed into the main fuel system 105 b is supplied from the main fuel injection hole 28 to the combustion chamber 300. Under the condition that the fuel supply pressure is equal to or higher than the crack pressure of the check valve 37c, the fuel is supplied to the pilot fuel systems 104a, 104b, 104c and the main fuel systems 105a, 105b, 105c. The fuel that has flowed into the main fuel system 105c flows through the water injection system 107 and is supplied to the combustion chamber 300 from the water injection nozzle 13b.

  In the present embodiment, an atomizing air compressor 30 is provided to supply compressed air used for atomization or purging of fuel. The air compressed by the atomizing air compressor 30 is supplied to the atomizing air systems 108a, 108b, 108c. The atomizing air system 108a is connected to the downstream side of the shutoff valve 19a of the liquid fuel system 101 via the shutoff valve 31a. The atomizing air system 108b is connected to the downstream side of the check valve 37b of the main fuel system 105a via the shut-off valve 31b. The atomizing air system 108c is connected to the electromagnetic valve 33 and used as instrumentation air. Here, the electromagnetic valve 33 is configured to be opened when compressed air is supplied from the spray air system 108c, and closed when not supplied.

  The water injection system 103 includes a water tank 21 for storing water to be injected into the combustor, a water pump 22, a flow rate adjustment valve 18c, and a cutoff valve 19c, and branches to the water injection systems 106 and 107 downstream of the cutoff valve 19c. doing. The water injection system 106 is connected to the water injection nozzle 13a via a check valve 37d, and the water injection system 107 is connected to the water injection nozzle 13b via a check valve 37e. The water injection nozzle 13a is arrange | positioned in the same circumferential direction position as the flame propagation pipe 40, as shown to FIG.

  First, a fuel supply method when liquid fossil fuel is used in this embodiment will be described with reference to FIGS. FIG. 9 shows the relationship between the fuel supply pressure and the fuel flow rate at the time of ignition and acceleration of a gas turbine using liquid fossil fuel as fuel. When the liquid fossil fuel is ignited, the fuel flow rate is low and the fuel supply pressure is low. For this reason, the fuel supply pressure becomes equal to or lower than the crack pressure of the check valve 37 a, and the fuel is supplied from the pilot fuel injection hole 27 to the combustion chamber 300. At the time of ignition, the fuel supply pressure is low, and the differential pressure cannot be taken sufficiently, so that the fuel is difficult to atomize. Therefore, the atomizing air compressor 30 is started and the shut-off valve 31b is opened. The compressed air is supplied from the main fuel injection hole 28 to the combustion chamber 300 through the main fuel system 105b.

  The liquid fossil fuel supplied from the pilot fuel injection hole 27 is atomized by a shearing force generated by a speed difference from the compressed air supplied from the main fuel injection hole 28. The liquid fuel injected from the pilot fuel injection hole 27 is forcibly ignited by sparks of a spark plug or the like. In the gas turbine including the plurality of combustors 2, the combustion chambers 300 are connected by the flame propagation pipe 40. From the combustion chamber 300 forcibly ignited by the spark plug to form a flame, high-temperature combustion gas is circulated to the adjacent combustion chamber 300 through the flame propagation tube 40 to form flames in all the combustion chambers 300. By atomizing the fuel with compressed air, mixing of the fuel and air is promoted, and good ignition and flame propagation characteristics can be obtained.

  At the time of acceleration, the fuel flow rate increases more than at the time of ignition, so the fuel supply pressure exceeds the crack pressure of the check valve 37a. The atomizing air compressor 30 is activated even when the speed is increased, and the fuel is atomized by the compressed air. For this reason, compressed air is supplied to the fuel system 108c, and the electromagnetic valve 33 is open. For this reason, a part of the fuel is supplied from the water injection nozzle 13 a to the combustion chamber 300 through the pilot fuel system 104 c, the electromagnetic valve 33, and the water injection system 106.

  When the rotational speed of the gas turbine further increases at the time of speed increase, the fuel flow rate increases, the fuel supply pressure increases, and exceeds the crack pressure of the check valve 37b. At the same time, the atomizing air compressor 30 is stopped. As a result, the electromagnetic valve 33 is closed, the fuel supply to the water injection system 106 is stopped, and the fuel is supplied to the combustion chamber 300 through the pilot fuel system 104b and the main fuel system 105b.

  FIG. 10 shows the flow rates of liquid fossil fuel and water when the flow rate of water is controlled to be a constant ratio with respect to the gas turbine load in the third embodiment. The horizontal axis in FIG. 10 is the gas turbine load, and the vertical axis is the flow rate of the liquid fossil fuel and water. Water starts to be supplied from the low load condition of the gas turbine, and the flow rate gradually increases as the load increases. Since the liquid fossil fuel has a smaller fuel flow rate at the rated load than bioethanol, the fuel supply pressure is equal to or lower than the crack pressure of the check valve 37c. Therefore, the liquid fossil fuel is supplied from the pilot fuel system 104b and the main fuel system 105b, and the water is supplied from the water injection systems 106 and 107.

  Next, the case where bioethanol is used as a fuel will be described with reference to FIGS. FIG. 11 shows the relationship between the fuel supply pressure and the fuel flow rate at the time of ignition and acceleration of a gas turbine using bioethanol as fuel. When the bioethanol is ignited, the fuel flow rate is higher than that of the liquid fossil fuel, and the fuel supply pressure is equal to or higher than the crack pressure of the check valve 37a. At the time of ignition, the atomizing air compressor 30 is activated and the electromagnetic valve 33 is open, so that fuel is supplied to the combustion chamber 300 through the pilot fuel system 104 b and the water injection system 106. At this time, the water injection system 106 is connected to the water injection nozzle 13a arranged at the same circumferential position as the flame propagation tube 40. For this reason, at the time of ignition, the bioethanol supplied from the water injection nozzle 13a raises the flame temperature in the vicinity of the flame propagation tube 40, the temperature of the combustion gas flowing through the adjacent combustor increases, and flame propagation characteristics are improved.

  At the time of acceleration when bioethanol is used as the fuel, the fuel flow rate increases and the fuel supply pressure becomes higher than at the time of ignition, and exceeds the crack pressure of the check valve 37b. At the same time, the atomizing air compressor 30 is stopped and the solenoid valve 33 is closed, whereby the fuel supply to the water injection system 106 is stopped. Thereby, bioethanol is supplied to the combustion chamber 300 through the pilot fuel system 104b and the main fuel system 105b. If the electromagnetic valve 33 is not closed, the flow rate of fuel supplied from the water injection nozzle 13a to the combustion chamber 300 during load operation increases, and the metal temperature of the components constituting the combustor 2 may increase. When the fuel system is controlled as in the present embodiment, the fuel supply to the water injection system 106 is stopped after the speed-up process, and the rise in the metal temperature of the parts constituting the combustor 2 can be suppressed.

  FIG. 12 shows the flow rates of bioethanol and water when the flow rate of water is controlled to be a constant ratio with respect to the gas turbine load in the third embodiment. The horizontal axis in FIG. 12 is the gas turbine load, and the vertical axis is the flow rate of bioethanol and water. Water starts to be supplied from the low load condition of the gas turbine and is supplied to the combustor 2 from the water injection systems 106 and 107. When the load of the gas turbine increases and the fuel supply pressure of bioethanol becomes equal to or higher than the crack pressure of the check valve 37c, bioethanol is supplied to the water injection system 107. Therefore, under high load conditions, the water injection system 107 supplies water and bioethanol mixed fuel, and the water injection system 106 supplies only water.

  A table summarizing the operation contents of each condition of the gas turbine combustor according to the present embodiment described above is shown below.

  A feature of this embodiment is that a branch pipe branched from the pilot fuel flow path 104a is connected to the water injection system 106 via the check valve 37a and the electromagnetic valve 33. The electromagnetic valve 33 uses sprayed air as instrumentation air, and opens when the shut-off valve 31a is open and sprayed air is supplied to the main fuel flow path 105, and closes when sprayed air is not supplied. In some cases, the crack pressure of the check valve 37a is opened under the fuel flow condition at the time of ignition using bioethanol. In the conventional gas turbine combustor, if the crack pressure of the check valve 37b is set according to the liquid fossil fuel having a high calorific value and a low fuel flow rate, the fuel supply pressure is higher than the crack pressure of the check valve 37b when bioethanol is ignited. There was a possibility of becoming.

  In this case, bioethanol flows into the pilot fuel system 104 b and the main fuel system 105 b and is supplied to the combustion chamber 300 from the pilot fuel injection holes 27 and the main fuel injection holes 28. When bioethanol is supplied from the main fuel injection hole 28 at the time of ignition, the flow rate of the compressed air supplied from the main fuel injection hole 28 for atomization of the fuel decreases. As a result, the atomization of bioethanol is impaired, and the ignition characteristics may be reduced.

  On the other hand, when bioethanol is ignited in the configuration of this embodiment, a part of the fuel flowing down the liquid fuel system is branched into the branch system and supplied from the water injection nozzle 13a as well as the pilot fuel injection hole 27. can do. For this reason, inflow of bioethanol into the main system at the time of ignition can be prevented, the flow rate of the compressed air supplied from the main fuel injection hole 28 does not decrease, and good ignition characteristics can be obtained. Moreover, since bioethanol is supplied to the water injection nozzle 13a arranged at the same circumferential position as the flame propagation tube 40, the flame temperature in the vicinity of the flame propagation tube 40 rises, and the flame propagation characteristics can be improved.

By setting it as the above structure, the ignition characteristic and flame propagation characteristic of a combustor can be improved. Moreover, the metal temperature rise of a combustor component can be suppressed and a highly reliable combustor can be provided.

DESCRIPTION OF SYMBOLS 1 Compressor 2 Combustor 3 Turbine 4 Generator 5 Diffuser 6 Outer cylinder 7 Inner cylinder 8 End cover 9 Transition piece 10 Swirler 11 Liquid fuel nozzle 12 Gas fuel nozzle 13 Water injection nozzle 14 Bioethanol fuel tank 15 Liquid fossil fuel tank 16 Gas fuel tank 17 Liquid fuel pump 18 Flow control valve 19 Shut-off valve 20 Vaporizer 21 Water tank 22 Water pump 23a Check valve (liquid fuel system)
23b Check valve (water injection system)
23c Check valve (pilot fuel system)
23d Check valve (water injection system, Example 3)
24 Liquid fuel flow meter 25 Water flow meter 26 Control device 27 Pilot fuel injection hole 28 Main fuel injection hole 30 Atomizing air compressor 31 Shut-off valve 33 Solenoid valve 37 Check valve 40 Flame propagation pipe 101 Liquid fuel system 102 Gas fuel system 103 Water Injection system 104 Pilot fuel system 105 Main fuel system 106 Water injection system 1 (Example 3)
107 Water injection system 2 (Example 3)
108 Atomizing air system 200 Compressed air 201 Cooling air 202 Combustion air 203, 205 Diffusion flame 204 Combustion gas 300 Combustion chamber

Claims (6)

In a gas turbine combustor capable of burning a plurality of fuels having different calorific values,
A combustion chamber for burning fuel and air;
A liquid fuel nozzle for injecting liquid fuel into the combustion chamber;
A liquid fuel system capable of supplying the liquid fuel nozzle with a first liquid fuel and a hydrophilic second liquid fuel having a lower calorific value per unit volume than the first fuel;
A first water injection nozzle for injecting water into the combustion chamber;
A first water injection system for supplying water to the first water injection nozzle;
Liquid fuel flowing down the liquid fuel system under a condition where the flow rate of the liquid fuel flowing down the liquid fuel system is a predetermined amount or more determined in a range larger than the fuel flow rate under the rated load condition of the first liquid fuel A gas turbine combustor comprising: a first branch pipe that branches a part of the first branch into the first water injection system. The gas turbine combustor according to claim 1.
Fuel flow rate measuring means for measuring the flow rate of the liquid fuel flowing down the first branch pipe;
Water flow measuring means for measuring the flow rate of water flowing down the first water injection system;
Gas turbine combustion comprising: a control device for controlling a flow rate of water flowing down the first water injection system based on an indication value of the fuel flow rate measurement means and an indication value of the water flow rate measurement means vessel. The gas turbine combustor according to claim 1 or 2,
The liquid fuel system includes a pilot fuel system and a main fuel system in which fuel flows down under a condition of a predetermined fuel flow rate or more;
A spray air system for supplying spray air to the main system;
A second water injection nozzle for injecting water into the combustion chamber;
A second water injection system for supplying water to the second water injection nozzle;
A second branch flow path for branching a part of the fuel flowing down the liquid fuel system to the second water injection system in a fuel flow rate condition at the time of ignition of the second fuel;
A gas turbine combustor provided with an electromagnetic valve provided in the second branch system and opened when atomized air is supplied to the liquid fuel nozzle. The gas turbine combustor according to claim 3.
A flame propagation pipe connecting the combustion chamber and the combustion chamber of another adjacent combustor;
The gas turbine combustor, wherein the second water injection nozzle and the flame propagation tube are provided in the same phase in the circumferential direction of the gas turbine combustor. The fuel supply method for a gas turbine combustor according to claim 2,
A fuel supply method for a gas turbine combustor, wherein a flow rate of water flowing down the water injection system is adjusted so as to be proportional to a flow rate of liquid fuel flowing down the first branch pipe. In the gas turbine combustor fuel supply method according to any one of claims 1 to 3,
A fuel supply method for a gas turbine combustor, wherein bioethanol is supplied as the second liquid fuel.