JP2011190783A - Liquid fuel burning gas turbine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve efficiency of a whole system, by reducing soot and dust, and a NOx emission concentration, in a gas turbine power generation system supplying liquid fuel and atomization air for atomizing the liquid fuel to a combustor to drive a gas turbine. <P>SOLUTION: The gas turbine includes: a gas turbine compressor 23 compressing air; the combustor 22 mixing and burning air with the liquid fuel 5 compressed by a gas turbine compressor 23 to generate combustion gas 25; a turbine 26 driven by the combustion gas 25 generated by the combustor 22; and a means for supplying the atomization air 4 atomizing the liquid fuel 5. The gas turbine further includes a mixer 2 supplying water to the atomization air 4, and atomization mixed fluid 6 as fluid from the mixer 2 is supplied to the combustor 22. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a liquid fuel-fired gas turbine, and more particularly to a structure and operation method for operating a gas turbine that is required to reduce dust and NOx with high efficiency.

  In a conventional liquid fuel-fired gas turbine combustor, a spray air system is adopted as a countermeasure for atomization of liquid fuel. In this atomizing air system, air is ejected at high speed around the liquid fuel ejection hole of the burner, the liquid fuel is atomized by the shearing force of the air and the liquid fuel, and the mixing of the liquid fuel and the combustion air is promoted. As a result, the ignition performance of the combustor is improved, soot in the exhaust combustion gas can be reduced, and the local high temperature region contributing to NOx generation in the combustion field can be reduced, so that the NOx emission amount is reduced.

  Further, the conventional gas turbine combustor adopts a water injection method in order to reduce the NOx emission amount. This reduces the local high temperature region of the combustion field by injecting water.

JP 2001-227745 A JP 2003-21309 A JP 2008-89298 A

  As combustors according to conventional spray air and water injection systems, for example, those described in JP 2001-227745 A, JP 2003-21309 A, and JP 2008-89298 A are known. Each of the disclosed combustors has a structure in which oil, water, and atomized air, which are liquid fuels, are jetted from a burner end face or near the end face to atomize the oil and reduce NOx emissions. However, the disclosed invention is a structure in which oil, water and spray air are separately supplied and mixed and atomized at the throat portion of the burner outlet, and a structure in which oil, water and spray air are mixed in advance is adopted. Not done.

  In order to atomize the liquid fuel by increasing the spray flow rate of the spray air, the supply pressure of the spray air that is higher than the discharge air of the gas turbine compressor is required. Usually, the atomizer compressor for generating the spray air Is installed. Since the temperature of the sprayed air discharged from the atomizing compressor becomes high during the compression process, if this high-temperature air is supplied around the liquid fuel flow path, the liquid fuel may coke, and the sprayed air is supplied to the burner. The atomizing air is cooled by a cooler before. Thus, the efficiency of the entire system is reduced by the power of the atomizing compressor and the cooling of the atomized air for atomizing the liquid fuel.

  In the case of the water injection method, it is necessary to effectively supply water to the local high temperature region of the combustion field and lower the combustion temperature. In the case of trying to decrease NOx by increasing the water supply amount There is a risk of causing unstable combustion such as misfire and flicker.

  The object of the present invention is to reduce the power of the atomizing compressor, the heat loss of the atomizing air, and the water injection amount when the atomizing air method or the combination method of atomizing air and water injection is used in the gas turbine power plant as described above. In addition to improving the efficiency of the entire system, an effective water supply method is adopted to provide a gas turbine that reduces NOx emissions and an operation method thereof.

  The present invention injects water into a spray air system for supplying to a combustor with respect to spray air for atomizing liquid fuel discharged from an atomizer compressor or a gas turbine compressor, and mixes the spray air and water. The main feature is the provision of a mixer.

  The present invention also monitors the temperature and pressure of the atomizing air supplied to the above-mentioned mixer or the temperature and pressure of the atomized air and water or steam mixed fluid after mixing, or the temperature and pressure of both. It is characterized by controlling the amount of water supplied.

  Further, the present invention comprises a structure in which liquid fuel or liquid fuel and water are further mixed in a mixing chamber inside the burner after the sprayed air or the mixed fluid is supplied to the burner of the combustor, and the combustion side end face of the burner Thus, the mixed fluid can be ejected.

  According to the present invention, the power of the atomizing compressor, the heat loss of the atomizing air, and the water injection amount are reduced to improve the efficiency of the entire system, and the gas that adopts an effective water supply method to reduce the NOx emission amount. It is to provide a turbine and a method for operating the turbine.

The figure which showed the gas turbine system in connection with this invention. Example 1 The figure which showed the gas turbine system in connection with this invention. (Example 2) The figure which showed the relationship between the water flow rate and the temperature of mixed fluid. (Example 2) The figure which showed the relationship between the water flow rate and the spraying air flow rate. (Example 2) The figure which showed the operating method of the gas turbine concerning this invention. (Example 2) The figure which showed the gas turbine combustor in connection with this invention. (Example 3) The figure which showed the gas turbine combustor in connection with this invention. Example 4

  When the atomizing air method or the combination method of atomizing air and water injection is used in a gas turbine power plant, the power of the atomizing compressor, the heat loss of atomizing air, and the amount of water injection are reduced and the efficiency of the entire system is improved. An effective water supply system was adopted to realize a system that reduces NOx emissions, the structure of the combustor, and its control method.

  As an embodiment using the present invention, a system configuration of a gas turbine is shown in FIG. The system is composed of a liquid fuel 5 supply system, a spray air 4 supply system, a water tank 1 and a supply system 7, a spray air 4 and water mixer 2, a combustor 22, a gas turbine compressor 23, a turbine 26 and a generator 27. Is done. Here, kerosene, light oil, A heavy oil or the like is generally used as the liquid fuel 5 in the gas turbine.

  When the gas turbine is started, the air 17 pressurized by the liquid fuel 5 and the atomizing compressor 15 is supplied to the combustor 22 as atomized air 4, and the liquid fuel 5 is atomized by the atomized air 4 to ignite the combustor 22. . When the gas turbine is started, the pressure inside the combustor 22 is low, and therefore the supply pressure of the spray air 4 is also low. Therefore, the temperature of the spray air 4 is equal to or less than the coking temperature of the liquid fuel 5. In the process of gas turbine start-up acceleration and partial load operation, the discharge pressure of the gas turbine compressor 23 increases, the supply pressure of the atomizing compressor 15 and the temperature of the atomizing air 4 rise, and the coking of the liquid fuel 5 occurs. When the temperature becomes higher than the temperature, the temperature of the spray air 4 can be lowered by supplying water to the mixer 2 installed in the supply system of the spray air 4 by the water tank 1 and the water pump 3. At this time, in order to prevent draining in the system, the mixer 2 has a structure capable of atomizing the water supplied to the mixer 2, for example, a water spray mechanism, and the water supplied into the mixer 2 is supplied to the mixer 2. It is desirable to evaporate all the water vapor. In order to prevent drain generation and to effectively lower the temperature of the spray air 4, the water flow control valve 10 and the spray air flow control valve 11 control the flow rate of the water supplied to the mixer 2 and the spray air 4. To do. The atomized mixed fluid 6 of atomized air and water vapor mixed in the mixer 2 is supplied to the combustor 22 to atomize the liquid fuel 5. This not only reduces the amount of dust generated, but also allows water vapor, which is an inert gas, to be supplied around the droplets when the liquid fuel 5 is atomized. Can be reduced. In addition, since the temperature of the spray air 4 that has conventionally been lowered by the heat exchanger can be lowered only by supplying water, a cooling heat exchanger is not necessary, and the amount of spray air that is supplied with water can be reduced. Furthermore, since the water vapor contained in the spray mixed fluid 6 supplied to the combustor 22 as the working fluid of the turbine 26 can be used, the efficiency of the entire system can be improved.

  When the gas turbine load is increased and the supply amount of the liquid fuel 5 is increased, the combustion temperature of the combustor 22 is increased, so that the combustion is stabilized and the generation amount of dust is reduced. Moreover, since the supply pressure of the liquid fuel 5 increases, atomization of the liquid fuel 5 alone is promoted by pressure spraying. For this reason, the atomizing air pressure for atomizing the liquid fuel 5 can also be reduced, and instead of the atomizing compressor 15, the extraction air 16 from the gas turbine compressor 23 is controlled by the extraction air flow rate adjusting valve 12 and used as the atomizing air 4. Then, the power of the atomizing compressor 15 can be suppressed, and the efficiency of the entire system is improved.

  As a second embodiment using the present invention, a system configuration of a gas turbine is shown in FIG. This system is different from the system shown in the embodiment of FIG. 1 in that the pressure / temperature / flow rate measuring device 30 is upstream of the mixer 2 of the four atomizing air systems, and the temperature measuring device is upstream of the combustor 22 of the atomizing fluid system. 31 is installed. The pressure / temperature / flow rate measuring device 30 outputs the measured physical property values to the computing device 32, and uses the valve opening calculated from the physical property values by the computing device to use the water in the first water supply system 8. The flow control valve 13 is controlled. In addition, a drain trap 33 is provided downstream of the temperature measuring device 31 to separate the drain generated in the spray mixed fluid 6. Further, a second water supply system 9 is provided which can branch from the supply system 7 and supply water directly to the combustor 22. The flow rate of water supplied to the combustor 22 by the second water flow rate adjustment valve 14 is set. Control. The mixer 2 has a simple structure in which the water spray nozzle 51 is provided in the supply pipe for the spray air 4 to reduce the cost.

  When water is supplied to the atomizing air 4 in the mixer 2, it is conceivable that water that has not evaporated remains in the mixer 2 and in the downstream system of the mixer 2 as a drain. When this drain is conveyed and supplied to the combustor 22, not only atomization of the liquid fuel 5 is suppressed but also a mass of water is supplied to the combustion field, thereby causing unstable combustion. The amount of water that can be supplied to the atomizing air 4 as water vapor is determined by the flow rate, pressure, and temperature of the atomizing air 4 as saturated water vapor. FIG. 3 shows the relationship between the amount of water injected into the mixer 2 and the temperature of the spray mixed fluid of the spray air 4 and water vapor. When the ratio of the flow rate of water to the atomized air 4 is increased, the temperature of the atomized mixed fluid 6 decreases and reaches the saturation temperature Tr shown in the figure. This temperature depends on the ratio of the flow rate of water to the sprayed air 4 and the pressure inside the mixer 2, and becomes the lowest temperature at which all water becomes water vapor. Under this condition, the maximum water flow rate Wr supplied to the mixer 2 is determined. In FIG. 2, if the flow rate, pressure and temperature of the atomizing air 4 supplied to the mixer 2 can be monitored with a measuring instrument and the water supply limit value Wr can be calculated with a calculator, the first water flow rate adjusting valve is controlled to control the water. It becomes possible to prevent the draining of. In addition, even when all the water in the mixer 2 becomes water vapor, the temperature of the spray mixed fluid 6 decreases due to natural heat dissipation or the like in the system that supplies the spray mixed fluid 6 to the combustor 22, and drainage is generated. There is a fear. In particular, when the gas turbine is accelerated or when the load changes, it is considered that the temperature of the spray mixed fluid becomes unstable. As in this embodiment, the temperature of the spray mixed fluid 6 is as close to the combustor 22 as possible. It is desirable to monitor temperature. Further, even when drain is generated in the spray mixed fluid 6, the drain can be separated by the drain trap 33, and this drain is reused by being supplied to the water tank 1 or the second water supply system 9. Is possible.

  When water is supplied to the mixer 2, the temperature of the spray mixed fluid 6 decreases as shown in FIG. 3, and the flow rate of the spray mixed fluid 6 increases by the amount of water supplied. Therefore, when the mass flow rate of the spray mixed fluid 6 is kept constant, the flow rate of the spray air 4 can be reduced. FIG. 4 shows the amount of water injected into the mixer 2. The relationship of the spray air flow rate in the case of keeping the mass flow rate of the spray mixed fluid 6 constant is shown. By supplying water to the atomizing air 4, the amount of atomizing air can be reduced, and the power of the atomizing compressor 15 can be reduced.

  In the present embodiment, a second water supply system 9 that branches from the supply system 7 and can supply water directly to the combustor 22 is provided. This is because when the gas turbine becomes heavily loaded and the combustion temperature rises, the steam from the mixer 2 alone may not achieve a sufficiently low NOx, and the second water supply system 9 will bring it into the combustion field. Water is directly injected to reduce NOx emissions.

  As an embodiment of gas turbine operation using the system of FIG. 2, changes over time in the gas turbine rotation speed and load, liquid fuel flow rate, spray air flow rate, and water flow rate are shown in FIG. At the time of ignition and startup acceleration of the gas turbine, the liquid fuel 5 is atomized using the atomized air 4 supplied from the atomizing compressor 15. As the rotational speed of the gas turbine increases, the liquid fuel flow rate and the amount of atomizing air increase, and the temperature of the atomizing air 4 further increases. When the gas turbine reaches a no-load rated speed operation, the atomizing air temperature is generally about 300 ° C. due to adiabatic compression. At this time, in order to prevent coking of the liquid fuel 5 by the sprayed air 4, water is supplied to the mixer 2, the temperature of the sprayed air 4 is lowered, and after mixing, the sprayed mixed fluid 6 is supplied to the combustor 22. As shown in FIG. 5, the flow rate of the atomizing air 4 can be reduced by the amount of water supplied. After the gas turbine starts to increase the load, the combustion is stable and the dust discharge is reduced, the supply source of the atomizing air 4 is switched from the atomizing compressor 15 to the gas turbine compressor 23, and the gas turbine compressor discharge air 24 The bleed air 16 is used as the atomizing air 4. When the gas turbine load further increases and the NOx emission amount increases, water is directly supplied from the second water supply system 9 to the combustor 22 to spray the combustion field and reduce the NOx emission concentration at high load. By adopting this gas turbine operation method, it is possible to realize operation with high efficiency and reduced NOx emission from the start of the gas turbine to the rated load.

  An example of an optimal combustor configuration using the system of FIG. 2 is shown in FIG. FIG. 6 shows a cross-sectional view of the combustor 22. In the combustor 22, combustion gas 25 is generated by the gas turbine compressor discharge air 24 and the liquid fuel 5. The generated combustion gas 25 rotates the turbine 26 and is generated by the generator 27.

  As shown in FIG. 6, the combustor 22 is surrounded by an outer cylinder 43 and an end flange 46, and is composed of a combustion chamber 45 surrounded by an inner cylinder wall 44 and a burner 49 that supplies the liquid fuel 5 to the combustion chamber 45 and burns it. The

  Water supplied from the liquid fuel 5, the spray air 4 or the spray mixed fluid 6, and the second water supply system 9 is supplied to a burner 49 installed on the central axis of the combustor 22. The burner 49 includes a mixing chamber 40 inside, and a fuel spray nozzle 52 that sprays the liquid fuel 5 into the mixing chamber 40 is installed. Further, a spray air swirler 50 is provided around the fuel spray nozzle 52, and the spray air 4 or the spray mixed fluid 6 is supplied to the mixing chamber 40 with a swirl flow to promote atomization of the liquid fuel 5. A water spray nozzle 51 for spraying water supplied from the second water supply system 9 is installed in the supply part of the spray air 4 or the spray mixed fluid 6 upstream of the spray air swirler 50, and the spray air 4 or spray mixing is performed. Mix water into fluid 6.

  Even when water does not evaporate by mixing the water supplied from the second water supply system 9 into the spray air 4 or the spray mixed fluid 6 immediately before being supplied to the mixing chamber 40 in this way, Water is supplied to the mixing chamber 40 in the form of mist by the spray nozzle 51. Further, by providing the mixing chamber 40, the liquid fuel 5 and water can be dispersed in the spray air 4 or the spray mixed fluid 6 in a mist form. The mixed fluid in which the liquid fuel 5 and water droplets are dispersed is supplied to the combustion chamber 45 downstream of the mixing chamber 40 and combusts. Thus, the micro explosion caused by the rapid evaporation of water droplets in the vicinity of the droplets of the liquid fuel 5 in the combustion field further atomizes the liquid fuel 5 to reduce the dust and NOx emission concentration.

  An air swirler 54 is provided around the mixing chamber 40 of the burner 49 to supply the gas turbine compressor discharge air 24 to the combustion chamber 45 with swirling, and water is supplied to the gas turbine compressor discharge air 24 supplied to the air swirler 54. A water spray nozzle 51 capable of spraying is installed. By dividing the water supplied to the combustor 22 into the mixing chamber 40 and the gas turbine compressor discharge air 24, an extreme temperature drop in the combustion field can be prevented and the gas turbine can be operated without impairing the combustion stability. It becomes.

  A second embodiment of the optimum combustor configuration using the system of FIG. 2 is shown in FIG. In the present embodiment, a water spray nozzle 51 for spraying water supplied from the second water supply system 9 to the mixing chamber 40 is installed in the embodiment of FIG. A mixed fluid spray nozzle 53 is provided downstream of the mixing chamber 40.

  In this way, by making the structure capable of spraying water directly into the mixing chamber 40, the liquid fuel 5 and water can be dispersed in the spray air 4 or the spray mixed fluid 6 in the form of mist, and the spray air, water vapor, liquid The fuel 5 and water droplets can be mixed uniformly. The mixed fluid in which the liquid fuel 5 and water droplets are dispersed is sprayed again into the combustion chamber 45 by the mixed fluid spray nozzle 53 provided downstream of the mixing chamber 40 and supplied to the combustion field. Since the liquid fuel 5 and the water are sprayed in two stages in this way, atomization is promoted in the combustion chamber 45, and in the combustion field, a micro explosion due to rapid evaporation of water droplets occurs in the vicinity of the liquid fuel 5 droplets. Further, the liquid fuel 5 is atomized to reduce the dust and NOx emission concentration without impairing the combustion stability.

  The gas turbine of each embodiment described above includes a gas turbine compressor 23 that compresses air, and a combustor that generates combustion gas 25 by mixing and burning the air compressed by the gas turbine compressor 23 and the liquid fuel 5. 22 and a turbine 26 driven by the combustion gas 25 generated by the combustor 22, and water is supplied to the spray air 4 in a gas turbine having means for supplying the spray air 4 for atomizing the liquid fuel 5. A mixer 2 is provided, and a spray mixed fluid 6 that is a fluid from the mixer 2 is supplied to the combustor 22.

  In such a combustor, the temperature of the high-temperature sprayed air discharged from the compressor can be lowered by supplying water to the sprayed air and mixing it, and a cooler using heat exchange is not necessary. . At the same time, since the steam and air after mixing can be used as the working fluid for atomizing the liquid fuel, the amount of atomized air generated can be reduced. Moreover, since the supplied water can be used as a working fluid that is supplied to the gas turbine combustor together with the atomized air to drive the turbine, the efficiency of the entire system including the compressor power is improved. Further, the water vapor contained in the atomized air can effectively reduce the NOx emission concentration by lowering the temperature of the high temperature combustion region in the vicinity of the burner.

  Further, the above-described embodiment includes the pressure / temperature / flow rate measuring device 30 which is a measuring means for measuring at least one of the flow rate, temperature, and pressure of the atomizing air supplied to the mixer 2. Based on this information, there is provided means for controlling the flow rate of water supplied to the mixer 2. By monitoring the temperature and pressure of the sprayed air supplied to the mixer 2 and the fluid after mixing, the amount of water that can be evaporated in the sprayed air can be controlled. In the system supplied to the burner, the steam can be prevented from being drained and unstable combustion can be suppressed.

  In the combustor of each embodiment, after supplying a mixed fluid of spray air and water vapor to the burner of the combustor, liquid fuel or liquid fuel and water are sprayed into the mixed fluid, and after mixing, the mixed fluid is burned from the burner end face to the combustion field. By spraying the liquid fuel, the liquid fuel can be atomized in two stages. Further, as in Example 2, if a first water supply system 8 for supplying water to the mixer 2 and a second water supply system 9 for supplying water to the combustor 22 are provided separately from this system, Furthermore, liquid fuel and water can be mixed in droplets by spraying water. Then, the explosion due to the rapid evaporation of water near the liquid fuel droplets further atomizes the liquid fuel, and the NOx emission amount and the dust emission amount can be effectively reduced.

  By adopting the structure and control method of each embodiment, the power of the atomizing compressor, the heat loss of spray air and the amount of water injection are reduced to improve the efficiency of the entire system, and the gas with reduced NOx and dust emission A turbine power plant can be operated.

DESCRIPTION OF SYMBOLS 1 Water tank 2 Mixer 3 Water pump 4 Spray air 5 Liquid fuel 6 Spray mixed fluid 7 Supply system 8 1st water supply system 9 2nd water supply system 10 Water flow rate adjustment valve 11 Spray air flow rate adjustment valve 12 Extraction air Flow adjustment valve 13 First water flow adjustment valve 14 Second water flow adjustment valve 15 Atomizing compressor 16 Extracted air 17 Air 22 Combustor 23 Gas turbine compressor 24 Gas turbine compressor discharge air 25 Combustion gas 26 Turbine 27 Power generation Machine 28 Exhaust gas 30 Pressure / temperature / flow rate measuring device 31 Temperature measuring device 32 Calculator 40 Mixing chamber 43 Outer tube 44 Inner tube wall 45 Combustion chamber 46 End flange 47 Air injection hole 49 Burner 50 Spray air swirler 51 Water spray nozzle 52 Fuel Spray nozzle 53 Mixed fluid spray nozzle 54 Air swirler

Claims (9)

A compressor for compressing air;
A combustor that generates combustion gas by mixing and burning air compressed by the compressor and liquid fuel;
A turbine driven by combustion gas generated in the combustor,
In a gas turbine having means for supplying atomized air for atomizing the liquid fuel,
A gas turbine comprising a mixer for supplying water to the atomized air, and configured to supply a fluid from the mixer to the combustor. The gas turbine of claim 1.
Means for measuring at least one of the flow rate, temperature, and pressure of the spray air supplied to the mixer, and for controlling the flow rate of water supplied to the mixer based on information of the measurement means A gas turbine power generation system comprising: The gas turbine according to claim 1 or 2,
The gas turbine according to claim 1, wherein the atomized air is a part of the compressed air generated by the compressor. In the gas turbine according to any one of claims 1 to 3,
A gas turbine comprising: a first water supply system that supplies water to the mixer; and a second water supply system that supplies water to the combustor. The gas turbine according to claim 4.
The combustor,
A water spray nozzle for spraying water from the second water supply system onto the fluid from the mixer;
A gas turbine comprising: a mixing chamber for mixing the fluid sprayed with water by the water spray nozzle and the liquid fuel. The gas turbine according to claim 4.
A gas turbine comprising a water spray nozzle for spraying water from the second water supply system into the mixing chamber. The gas turbine according to any one of claims 4 to 6,
The combustor,
A mixing chamber that mixes the fluid from the mixer and the liquid fuel; a compressed air supply system that supplies compressed air generated by the compressor;
A gas turbine comprising: a system for supplying water from the second water supply system to the compressed air supply system. The gas turbine according to any one of claims 5 to 7,
The combustor includes a combustion chamber downstream of the mixing chamber;
A gas turbine comprising a liquid fuel spray nozzle for spraying the fluid in the mixing chamber onto the combustion chamber. A compressor for compressing air;
A combustor that generates combustion gas by mixing and burning air compressed by the compressor and liquid fuel;
A turbine driven by combustion gas generated in the combustor,
In a gas turbine operation method comprising means for supplying atomized air for atomizing the fuel,
A method for operating a gas turbine, comprising: supplying water to the combustor after supplying water to lower the temperature.

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