JP4939179B2 - Gas turbine combustor and operation method thereof - Google Patents

Description

  The present invention relates to a gas turbine combustor and an operation method thereof. More specifically, the present invention relates to a gas turbine combustor capable of co-firing a liquid fuel vaporized at a temperature lower than the combustion air temperature and natural gas, and an operating method thereof.

  In recent years, it has been required to suppress the generation of nitrogen oxides (NOx) and suspended particulate matter (SPM) that adversely affect the environment, and the use of biomass fuel is required as a fuel to replace petroleum.

  Gas turbine combustors that use liquid fuels derived from fossil fuels such as light oil and heavy oil A emit higher concentrations of NOx than gas turbine combustors that use gas fuels such as LNG (liquefied natural gas), and SPM There is also the possibility of discharging the causative smoke. For this reason, the reduction has been achieved by improving the fuel injection method, devising the structure of the burner, and injecting water or steam into the combustor, but it can be said that sufficient effects have been obtained. There is nothing. In particular, NOx has not been sufficiently reduced, and an expensive flue gas denitration apparatus has been installed. Furthermore, there is also a problem that energy loss increases when water or water vapor is injected.

On the other hand, Japan is obligated to reduce the amount of greenhouse gas emissions such as carbon dioxide (CO ₂ ) by concluding the Kyoto Protocol, but CO ₂ emitted by the combustion of biomass is emitted into the atmosphere during the growth of organisms. because it is absorbed CO ₂ from in the combustion of the biomass does not increase CO ₂ (CO ₂ neutral). For this reason, substituting petroleum-based fuel with biomass fuel can greatly contribute to CO ₂ emission reduction. Furthermore, in Japan, the “Special Measures Law Concerning the Use of New Energy by Electric Power Companies” (RPS Law) has been enforced, and electricity generated by new energy, including biomass, is used at a certain rate for electric power companies. It is obligatory.

  Therefore, a method of mixing solid biomass fuel such as wood chips into coal and combusting it with a power generation boiler, a method of combusting with a power generation gas turbine combustor, a method of gasifying and combusting with a power generation gas turbine combustor, etc. are studied. ing.

  For example, a method of burning solid biomass fuel with a gas turbine combustor has been proposed (Patent Document 1). In this method, fossil fuel and biomass fuel are appropriately selected to generate combustion gas, impurities contained in the generated combustion gas are removed by a cyclone separator and then supplied to the gas turbine, and the cyclone separator outlet temperature is 800 It is necessary to keep the temperature below ℃. The reason is that the calorific value of the solid biomass fuel is low, the start-up operation and partial load operation cannot be performed only with the biomass fuel, the ash adheres to the turbine blades unless the ash generated by the combustion of the solid biomass fuel is removed, Since the causative substance of dioxin is contained in the biomass fuel, it is caused by generating dioxin unless the temperature is higher than 800 ° C.

  Further, a method has been proposed in which solid biomass fuel or the like is gasified and burned in a power generation gas turbine combustor (Patent Document 2). In this method, a water spray means is provided in a compressor of gasified gaseous fuel, water is sprayed in the process of compressing the gaseous fuel and evaporated in the compressor, and the gas temperature accompanying the compression using the endothermic effect at this time is used. It is necessary to suppress the rise of the gas and to increase the gas temperature of the gaseous fuel to 300 ° C. or higher. The reason for this is that compressing high-temperature gaseous fuel further increases the temperature and the compressed energy becomes the same level as the energy generated by the gas turbine, resulting in a decrease in the output energy, and biomass. Combustible gas that gasifies etc. contains a component called tar that liquefies at low temperatures, and when the gas temperature becomes low, it becomes a highly viscous liquid and adheres to piping and equipment, causing problems such as clogging It is due to that. In Patent Document 2, as a conventional method for avoiding the problem due to the tar content, a method of thermally decomposing the tar content by increasing the gasification temperature and a method of removing the tar by washing the gas with water are described. In addition, there are disadvantages such as generation of energy loss and complicated equipment, and furthermore, as a conventional method that does not require compression of gaseous fuel, there is a method of performing gasification by pressurization, but a pressure vessel is required, It has the disadvantages of creating safety problems and increasing operating costs.

In order to suppress CO ₂ using an existing LNG gas turbine, it is reasonable to modify the LNG gas turbine so that it can be co-fired with plant-derived liquid fuel. Then, the gas turbine which can apply the bioethanol liquefied by using vegetable oil as a raw material with respect to solid or gasification biomass fuel is proposed (patent document 3). In this method, a multistage combustion combustor comprising a diffusion combustion section and a premix combustion section is employed, and alcohol is supplied to the diffusion combustion section and natural gas is supplied to the premix combustion section to burn each fuel. As a result, during low-load operation where diffusion combustion, that is, non-premixed combustion alone, is performed, by using alcohol with less NOx generation in non-premixed combustion, compared with a combustor using only natural gas, NOx can be suppressed. In addition to the gas turbines, gas turbines using liquid fuels such as kerosene, light oil, and A heavy oil have been put into practical use, and bioethanol can be applied to them, most of which are non-premixed combustion systems.

  On the other hand, a combustor using liquid fuel in a premixed combustion section has been proposed (Patent Document 4). In this method, a combustor is composed of a primary combustion zone and a secondary combustion zone, a gaseous fuel injection section for supplying a lean mixture of gaseous fuel to the secondary combustion zone via an annular premixing passage, and a liquid in the downstream Install a liquid fuel spray nozzle to introduce a lean mixture of fuel. As a result, since liquid fuel can also be premixed in the gas premixing passage, the liquid fuel can be burned close to lean premixed combustion, and NOx can be suppressed as compared with non-premixed combustion.

Furthermore, in recent years, DME (dimethyl ether) produced from natural gas, coal, biomass such as CO ₂ neutral, etc., alcohol fuels such as methanol and ethanol have attracted attention as new fuels. These fuels and the like are desired to be used for power generation with high thermal efficiency as part of fuel diversification in preparation for an energy crisis. In recent years, the gas turbine combined power plant (GTCC), which has an exhaust gas boiler that recovers the heat of exhaust gas and generates steam in the downstream of the gas turbine and uses the steam to turn the steam turbine, has attracted attention. Therefore, the power generation efficiency exceeds 50%, greatly exceeding the efficiency of conventional power generation facilities. On the other hand, DME originating from natural gas, coal and biomass, and alcohol-based fuels tend to have high production costs. By using such fuel with high production costs in the highly efficient GTCC, it is possible to reduce the cost per power generation. Most of the large gas turbines currently used for the electric power industry and most of the small and medium-sized gas turbines use natural gas as fuel to reduce nitrogen oxides (NOx). This is a state in which liquid fuel such as alcohol fuel cannot be used.

JP 2004-218532 A Japanese Patent Laid-Open No. 2002-221047 JP-A-6-193472 JP-A-8-261465

  However, these methods using solid biomass fuel such as wood chips have a low calorific value per mass of solid biomass, and also have poor collection efficiency and transport efficiency, and also require treatment of the generated ash or slag, There are problems such as inferior economy.

  Further, the method described in Patent Document 1 requires a cyclone separator, which increases the size of the equipment and increases the equipment cost, and may cause cyclone wear due to high-temperature ash. Furthermore, the temperature management of the cyclone inlet and outlet is required, and the control for that is complicated. Further, due to the heat resistance problem of the cyclone separator, the gas temperature is limited and the energy loss is large. Furthermore, trace components such as sodium and potassium contained in solid biomass fuel deteriorate materials such as turbines, but no countermeasures have been taken.

  In addition, the method of Patent Document 2 requires pure water, and also requires a water supply device and a control device, which increases equipment costs and operation costs. In addition, energy loss due to gasification of fuel cannot be prevented. Furthermore, the poor collection and transportation efficiency of solid biomass fuels and the need for processing costs for the generated ash or slag remain as common challenges. Furthermore, trace components such as sodium and potassium contained in solid biomass fuel deteriorate materials such as turbines, but no countermeasures have been taken.

  Further, in the method described in Patent Document 3, the alcohol is burned by non-premixed combustion that generates a large amount of NOx compared with premixed combustion even after switching to high load operation combined with premixed combustion. There is a problem that a sufficient NOx reduction effect cannot be obtained during load operation.

  Further, in the method described in Patent Document 4, liquid fuel is sprayed into the gas fuel and air mixture, and therefore, the liquid fuel spray is evaporated and further mixed with the gas fuel and air mixture. Become. Here, the spray particles of the liquid fuel cannot be burned as they are in the liquid state, but are burned by evaporating and reacting with air. Therefore, until the spray particles are completely evaporated, high-concentration liquid fuel vapor is distributed around the spray particles, and gaseous fuel is also added, so that a higher-concentration combustible gas is distributed. As a result, the distribution of the combustible gas concentration in the mixture of fuel and air injected into the combustor becomes non-uniform, and the portion with the high combustible gas concentration burns at a high temperature to generate a large amount of thermal NOx. Furthermore, in the worst case, it burns in the annular premixing passage, which can damage the combustor.

  Further, even if liquid fuel such as DME or alcohol is injected into the combustor together with natural gas to be mixed and burned, if it is sprayed and combusted in the combustor as a liquid, it will become non-premixed combustion. There is a possibility that a high temperature region may be generated and increase NOx. That is, there is a risk of causing temperature unevenness and combustibility unevenness in the combustor, increasing NOx, increasing carbon monoxide and unburned hydrocarbons, reducing the life of the turbine and the combustor, and causing backfire into the premixing nozzle. is there.

  An object of the present invention is to provide a gas turbine combustor and a gas turbine operating method capable of co-firing liquid fuel and gas fuel without increasing NOx. Furthermore, the present invention is a gas turbine combustion that emits less carbon dioxide and nitrogen oxides than a gas turbine combustor that burns only liquid fuel with a slight modification to an existing gas turbine combustor for natural gas. It is an object of the present invention to provide a gas turbine combustor that can reduce carbon dioxide emissions as compared with the case where only natural gas is used as fuel.

In order to achieve this object, a gas turbine combustor according to the first aspect of the present invention includes a premixing nozzle that uses a gas as a fuel and supplies a premixed gas in which the gas fuel is mixed with air to the combustor. In the combustor, gas gas is supplied as the main fuel under operating conditions above the load operation, and the gas is completely vaporized at the temperature of the combustion air supplied to the premixing nozzle or at a temperature lower than that, and the flow rate of the combustion air A liquid fuel injection port for injecting liquid liquid in the flow of combustion air upstream from the gas fuel injection port as a subordinate amount of liquid fuel with a concentration less than the lower limit of flammability limit, the liquid fuel is mixed with combustion air is mixed with the gas fuel after being completely vaporized, from a fully premixed nozzle as lean premixed mixture of vaporized liquid fuel and the combustion air and gas fuel It is supplied to the burn unit to co-firing, and to generate a combustion gas for driving the turbine. The gas turbine operation method according to the invention described in claim 5 is a gas turbine combustor comprising a premixing nozzle that supplies a premixed gas in which gas fuel is mixed with air to the combustor. While gas fuel is supplied as the main fuel under the above operating conditions, it is completely vaporized at the temperature of the combustion air supplied to the premixing nozzle or at a temperature lower than that, and the flammability limit for the flow rate of the combustion air The liquid fuel in an amount that is less than the lower limit is injected as a subordinate fuel in the form of a liquid upstream of the injection position of the gas fuel, and the liquid fuel is mixed with the combustion air and completely vaporized. A mixed and completely vaporized liquid fuel, combustion air, and gas fuel are supplied as a lean premixed gas from the premixing nozzle to the combustor for co-firing.

Therefore, the liquid fuel injected into the combustion air flow in the premixing nozzle is completely vaporized at the temperature of the combustion air or lower, so that it comes into contact with the combustion air. At the same time, completely vaporized and mixed. Moreover, since the liquid fuel is in an amount that is less than the lower limit of the flammability limit with respect to the combustion air, the liquid fuel is uniformly mixed without starting combustion. Thereafter, the fully vaporized and liquid fuel and combustion air and gas fuel is supplied to the combustor in the lean premixed mixture is mixed, causing lean premixed combustion in a combustor.

  Here, the liquid fuel used in the gas turbine combustor of the present invention is a liquid fuel that is completely vaporized at the temperature of the combustion air supplied to the premixing nozzle or at a temperature lower than that, such as an alcohol fuel. The use of a plant-derived alcohol fuel, more preferably bioethanol, more preferably a non-alcohol liquefied fuel such as LPG or DME, more preferably dimethyl ether.

According to the gas turbine combustor and the operation method thereof of the present invention, after the liquid fuel having a concentration below the lower limit of flammability is completely vaporized and mixed with air, the gas fuel is added to obtain a lean premixed gas . Therefore, even if liquid fuel is used as a subordinate fuel, lean premixed combustion is realized in the combustor, and NOx can be reduced as compared with a gas turbine that burns only liquid fuel. That is, since it is supplied into the combustor as a lean premixed mixture of completely vaporized liquid fuel, combustion air and gas fuel, it is possible to suppress the occurrence of temperature unevenness and combustibility unevenness in the combustor, and NOx It is possible to prevent the increase in carbon monoxide and unburned hydrocarbons and prevent the life of the turbine and the combustor from decreasing. Moreover, even if the liquid fuel burns near the liquid fuel nozzle, the temperature does not increase greatly because the flow rate of the liquid fuel is small, and it is safe.

Further, as compared with a boiler steam turbine power generation, since high energy efficiency by utilizing a gas fuel gas turbine combined power generation obtained can burn liquid fuel, because it can reduce the effective utilization i.e. fuel consumption energy, the CO ₂ The production amount can also be reduced.

  In addition, the existing gas turbine combustor for gas fuel is used to supply liquid fuel from a separate nozzle from the gas fuel, so the existing equipment gas supply system, gas fuel nozzle and gas fuel burner are used as they are or few Can be used in remodeling. Therefore, liquid fuel can be burned at the same time as gas fuel by adding a liquid fuel supply system and a liquid fuel nozzle, etc., and making slight modifications only with the accompanying changes. Development cost and development period can be shortened. In addition, the facility cost can be greatly reduced as compared with the case of newly installing a gas turbine for liquid fuel. In addition, since the normal operation using only the gas fuel is performed when the gas turbine is started and stopped, the operation is easy and stable.

  In addition, according to the invention of claim 2, which uses an alcohol fuel, since the alcohol fuel is vaporized at a relatively low temperature, the fuel gas supplied to the combustor is surely vaporized to realize lean premixed combustion. can do. As a result, the fuel can be used in a gas turbine combustor and fuel can be diversified.

Further, according bioethanol plant-derived inventions of claim 3, wherein used as the liquid fuel, there is a high collection efficiency and transportation efficiency as compared with the solid biomass fuels, was a serious obstacle to use biomass fuel This makes it possible to realize a stable supply of fuel and reduce the operating cost. Moreover, plant-derived liquid fuels contain inorganic components that cause ash and slag, chlorine that causes dioxins, sodium and potassium that cause corrosion of materials such as turbines, and fragrances that cause smoke and luminous flames. Since no aromatic hydrocarbons or cyclic hydrocarbons are contained, any problems caused by them can be eliminated. That is, ash, slag, and dioxins are not discharged, and the life of materials such as turbines can be extended. Furthermore, since it is used as it is as a liquid fuel, it is not necessary to gasify the fuel at a high temperature, and neither generation of tar nor pure water for removing tar is required. Moreover, CO ₂ emitted during combustion because biomass fuels are those originally attributed to atmospheric CO _2, not connected to the occurrence of a new CO _2, can contribute greatly to reducing emissions of CO _2. Therefore, compared with the case where only natural gas is burned in the gas turbine combustor for natural gas, it is possible to greatly contribute to CO ₂ emission reduction, and the increase of NOx and smoke emission amount is suppressed to a small amount within a dealable range. be able to. Further, when there use ethanol as a liquid fuel, since it is possible to completely vaporized at a temperature of the fuel gas after being compressed in order to supply to the gas turbine combustor, including means for heating the fuel gas There is no particular need, and additional equipment to the gas turbine combustor equipment can be reduced.

According to the invention described in claim 4 , even if dimethyl ether synthesized from low grade fuel such as waste plastic, lignite, and super heavy oil is used as a liquid fuel, compared with boiler steam turbine power generation, gas turbine combined power generation Since the energy efficiency of CO ₂ is high, the fuel consumption can be reduced, so that the amount of CO ₂ produced can be reduced. The same applies to the case where LPG or industrial alcohol is used as the liquid fuel. In addition, lignite and superheavy oil, which had a low utility value, and waste plastic that had to be disposed of at high cost can be used effectively, and gas fuel such as natural gas can be used with existing gas turbine equipment. Because mixed combustion is possible, diversification of fuel can be realized. Furthermore, when dimethyl ether produced using biomass as a raw material is used, a large CO ₂ reduction effect can be obtained.

Hereinafter, the configuration of the present invention will be described in detail based on embodiments shown in the drawings.
FIG. 1 shows an embodiment of a power generation system using the gas turbine combustor of the present invention. The gas turbine power generation system of this embodiment uses natural gas as a main fuel, and a gas turbine combustor 24 for natural gas, and a turbine driven by combustion gas supplied from the gas turbine combustor 24 for natural gas. 13, an air compressor 12 that supplies compressed air to the gas turbine combustor 24 for natural gas, a generator 11 that is arranged coaxially with the air compressor 12 and the turbine 13, and the generator 11 as a motor at startup And a switching device 14 for driving. The combustion gas generated by the combustor 24 is supplied to the turbine 13 to rotate the generator 11 to generate electric power. Although not shown in the figure, the connecting shaft between the air compressor 12 and the turbine 13 is provided with a clutch, and can be intermittently connected as necessary. The gas fuel as the main fuel is not particularly limited to the natural gas described above, and other gas fuels can be used.

  The gas turbine combustor 10 includes an inner cylinder 7 that forms a combustion chamber 26, a premixing nozzle 5 that forms a lean premixed gas at the inlet of the inner cylinder 7 and supplies it to the combustion chamber 26, and the premixing nozzle 5. An outer cylinder 6 serving as a housing that covers the periphery of the mixing nozzle 5 and the inner cylinder 7, and compressed air and combustion air supplied from the compressor 12 between the inner cylinder 7 and the outer cylinder 6 are supplied to the inner cylinder 7. And an air passage 25 that guides to the premixing nozzle 5 is formed.

  The premixing nozzle 5 of this embodiment includes a swirler 4, a liquid fuel nozzle 10, and a natural gas nozzle 3 in a cylindrical nozzle body 28 that forms a premixing chamber 27, and mixes liquid fuel and natural gas with air. The premixed gas can be supplied to the combustion chamber 26 of the inner cylinder 7. The liquid fuel nozzle 10 is connected to the liquid fuel tank 8 through the liquid fuel pipe 16 and is at a temperature lower than or lower than the temperature of the combustion air supplied to the premixing nozzle in the load operation or higher operation conditions. An amount of liquid fuel that is completely vaporized and has a concentration lower than the lower limit of the flammability limit with respect to the flow rate of the combustion air is provided so as to be injected into the premixing chamber 27 as a subordinate fuel. The installation position of the injection port of the liquid fuel nozzle 10, that is, the injection position of the liquid fuel is set upstream from the injection port of the natural gas, and is included in the flow of combustion air flowing into the premixing chamber 27 through the swirler 4. It is provided to be injected before the natural gas. The natural gas nozzle 3 is connected to the natural gas tank 1 via a natural gas pipe 15 and is provided so as to inject natural gas into the premixing chamber 27 as the main fuel. Therefore, the combustion air flowing into the premixing chamber 27 as a swirling flow by the swirler 4 first collides with the jet of liquid fuel, is mixed with the vaporized liquid fuel while vaporizing the liquid fuel, and then the jet of natural gas Colliding with natural gas. Then, a mixture of vaporized liquid fuel, natural gas, and combustion air is supplied from the premixing nozzle 5 into the combustion chamber 26. Reference numerals 2 and 9 in the figure denote flow rate control valves.

As the liquid fuel, any liquid fuel can be used as long as it is vaporized at the temperature of combustion air supplied to the premixing nozzle 5 or at a temperature lower than that. Alcohol fuel, more preferably plant-derived alcohol fuel. More preferably, bioethanol is used. Furthermore, liquefied fuel such as LPG or DME can be used as the liquid fuel. In particular, dimethyl ether produced from biomass fuel is used as the liquid fuel for reducing the CO ₂ emission of the gas turbine combustor. Is preferred. Furthermore, as the alcohol fuel, industrial alcohol, fuel alcohol, virgin alcohol fuel, or the like can be used.

  Here, when a part of the liquid fuel is vaporized in the pipe 16 of the liquid fuel supply system 18, the differential pressure at the injection port of the liquid fuel nozzle 10 opening in the premixing chamber 27 fluctuates, and the spray becomes unstable. The fuel flow rate also varies, and there is a risk that stable operation cannot be achieved. For this reason, it is preferable to maintain the liquid state in the pipe 16. Therefore, the liquid fuel is supplied to the liquid fuel nozzle 10 through the pipe 16 in a state where the liquid fuel is pressurized from the liquid fuel tank 8 of the liquid fuel supply system 18 without being heated, without being heated. . If the liquid fuel is liquid and is injected from the liquid fuel nozzle 10, it is not necessary to cool the liquid fuel, and it is sufficient to supply it without positively heating. However, when the vaporization temperature of the liquid fuel is much lower than the temperature of the compressed air that is the combustion air, the pipe 5 is made into a double pipe and a fluid such as cooling air or water is circulated outside. It is preferable not to vaporize in the pipe 5. Although not shown, temperature sensors are installed in the liquid fuel supply system 18 and the natural gas supply system 17 to monitor the fuel temperature.

  Fuel is usually supplied to the gas turbine at a pressure of 3 MPa or more. For this reason, there are fuels that become liquid when supplied to the gas turbine, even in a gaseous state at atmospheric pressure. A typical example of such a fuel is dimethyl ether. FIG. 6 shows the vapor pressures of ethanol, methanol, and dimethyl ether. For example, in the case of a gas turbine operated under a load operation or higher and a combustor pressure of 1 to 2 MPa and a combustor inlet temperature of 300 to 400 ° C., methanol is about 160 ° C. or less, ethanol is about 180 ° C. or less, dimethyl ether Vaporizes below about 70 ° C., so these fuels are completely vaporized below the temperature of the combustion air. For example, when supplying fuel to a gas turbine at 5 MPa, in order to spray the fuel in a liquid state, it is necessary to maintain methanol at about 210 ° C. or lower, ethanol at about 220 ° C. or lower, and dimethyl ether at about 120 ° C. or lower. There is.

  Table 1 shows the lower flammability limit values of methanol, ethanol, and dimethyl ether. Further, FIG. 7 shows the operation of the premix nozzle 5 when the combustor inlet temperature is 400 ° C., the combustor outlet temperature is 1500 ° C., and the weight ratio of liquid fuel to natural gas is changed to 0.3. The fuel concentration of the premixed gas of combustion air and vaporized liquid fuel is shown. This premixed gas is a premixed gas downstream of the liquid fuel nozzle 10 and upstream of the natural gas nozzle 3, and no natural gas is mixed therein. From these figures, if the weight ratio of liquid fuel to natural gas is 0.2 or less, the fuel concentration of the premixed gas is less than one-tenth of the lower limit of flammability for all three types of fuel. The risk of gas burning in the premixing nozzle 5 is very low. Next, FIG. 8 shows the average temperature of the combustion gas when the liquid fuel is ignited in the premixing nozzle 5, that is, the combustion gas temperature at the inlet of the natural gas nozzle. When the weight ratio of liquid fuel to natural gas is 0.2, the combustion gas temperature at the inlet of the natural gas nozzle is sufficiently low at about 530 ° C. or less in all three types of fuel, and even if liquid fuel is ignited in the premix nozzle However, there is no risk of damage to the combustor material or ignition of the natural gas in the premix nozzle.

  According to the gas turbine combustor configured as described above and the gas turbine power generation system using the gas turbine combustor, complete lean premixed combustion is established even when liquid fuel is mixed with fuel gas.

  In this gas turbine operation method, liquid fuel is supplied only under operating conditions that are higher than the load operation, and the gas turbine combustor is started and stopped by burning only natural gas in the same way as a normal gas turbine combustor for natural gas. It is carried out by letting. For example, the generator 11 is first driven as a motor and the air compressor 12 is rotated to supply air to the premixing nozzle 5 and the combustion chamber 26. Next, natural gas is injected from the natural gas nozzle 3 into the premixing nozzle 5 and mixed with the combustion air by the swirler 4, and then the premixed gas is supplied from the premixing nozzle 5 into the combustion chamber 26. 26 to burn. This combustion gas is supplied to the turbine 13 to rotate the turbine 13 and rotate the coaxial air compressor 12. As a result, special considerations due to the addition of liquid fuel are not required at the time of starting and stopping, and control at the time of starting and stopping is facilitated.

  Supply of natural gas is started under operating conditions that exceed the load operation. Liquid fuel is supplied from the liquid fuel tank 8 to the liquid fuel nozzle 10 as subordinate fuel, and is injected into the premixing chamber 27 of the premixing nozzle 5 and mixed with the combustion air flowing as a swirling flow. At this time, since the temperature of the combustion air is increased by the compression heat, the liquid fuel injected therein is completely vaporized by the temperature of the combustion air. Then, all of the liquid fuel evaporates, and is completely mixed with the combustion air and supplied downstream as a uniform and completely gaseous mixed fuel with no spots. Further, the vaporized mixture of liquid fuel and combustion air is further mixed with natural gas injected downstream of the liquid fuel in the premixing chamber 27 of the premixing nozzle 5 to form a lean premixed gas. Is injected into the combustion chamber 26. And the lean premixed combustion of the state which is not different from the case of only natural gas is realized.

  At this time, since the lean premixed gas obtained by mixing the vaporized liquid fuel and the natural gas is in the same state as the premixed gas of natural gas, the structure of the combustor for natural gas after the premixing nozzle 5 is used as it is. Therefore, low NOx combustion comparable to natural gas becomes possible. As a result, a remarkable NOx reduction effect can be obtained as compared with a combustor exclusively for liquid fuel. Further, the structure of the conventional combustor body for natural gas can be applied as it is only by changing the fuel supply structure such as the fuel supply system and the fuel nozzle, so that the development cost and development period of the combustor can be shortened. Furthermore, since the liquid fuel is vaporized and uniformly mixed with the combustion air and then mixed with natural gas, the fuel concentration in the portion where the liquid fuel is mixed with air is sufficiently thin, and there is little risk of ignition in the premixing nozzle. In addition to being safe, the liquid fuel is completely vaporized and can be sufficiently mixed with the air, so the uniformity of the premixed gas injected into the combustor is high, and a remarkable NOx reduction effect is obtained.

  FIG. 2 shows a second embodiment of the premixing nozzle. In the premixing nozzle 5 of this embodiment, a nozzle 29 having a double pipe structure in which the natural gas nozzle 3 and the liquid fuel nozzle 10 are concentrically arranged is arranged in the center of the nozzle body 28 and a swirler is provided at the entrance of the nozzle body 28. 4 is provided so as to form a swirling flow of combustion air around the nozzle 29. The nozzle 29 has the natural gas nozzle 3 on the inner side and the liquid fuel nozzle 10 on the outer side, and burns from the liquid fuel injection port 21 and the natural gas injection port 20 formed on the peripheral surface of the outer pipe that also serves as the liquid fuel nozzle 10. Each fuel is provided so as to be injected in a direction orthogonal to the flow of working air. The liquid fuel injection port 21 is disposed upstream of the natural gas injection port 20 with respect to the flow of combustion air. Then, the liquid fuel nozzle 10 is closed by the sealing block 30 disposed between the natural gas nozzle 3 and the liquid fuel nozzle 10 and between the liquid fuel injection port 21 and the natural gas injection port 20, so that the natural gas injection is performed. Only natural gas is injected from the mouth 20. The tip of the nozzle 29 is sealed with a conical block 31. Such a combustor can be easily modified by disposing the above-described nozzle 29 in place of the natural gas nozzle of a general natural gas premixed combustor provided with a natural gas nozzle on the central axis. The liquid fuel injection port 21 may be provided with many small-diameter injection ports, or a general pressure swirl spray method may be used. The liquid fuel in the liquid fuel nozzle 10 is heated by heat transfer from the combustion air. Therefore, in order to maintain a stable fuel injection state, it is necessary that the liquid fuel be kept in a liquid state in the nozzle until it is sprayed. Therefore, it is necessary to adopt an appropriate cooling structure based on the characteristics of the fuel, and to set the heat transfer area, fuel pressure, and residence time necessary for suppressing the temperature rise.

    The gas turbine combustor configured as described above can also realize complete lean premixed combustion using liquid fuel. That is, liquid fuel is injected from the liquid fuel injection port 21 into the flow of combustion air swirled by the swirler 4 disposed at the inlet of the premixing nozzle 5 and introduced into the premixing chamber 27. The liquid fuel is mixed with the combustion air by the effect of the swirler 4 and is completely vaporized by the heat from the combustion air to form a premixed gas. Natural gas is injected into the premixed gas from the natural gas injection port 20 disposed downstream of the liquid fuel injection port 21. The natural gas is further mixed with the premixed gas by the effect of the swirler 4 and injected into the combustion chamber 26 as a uniform premixed gas of the vaporized liquid fuel, natural gas, and combustion air, and performs low NOx lean premixed combustion. .

  FIG. 3 shows a third embodiment of the premixing nozzle. The premixing nozzle of this embodiment has a triple-pipe structure in which a nozzle outer tube 22 for flowing cooling air is provided on the outer side of the nozzle 29 composed of the natural gas nozzle 3 and the liquid fuel nozzle 10 of FIG. By cooling the outer periphery of the nozzle 10 with air and controlling the temperature of the liquid fuel, vaporization of the liquid fuel in the nozzle is prevented. Here, the liquid fuel injection port 21 and the natural gas injection port 20 are formed on the peripheral surface of the nozzle outer tube 22, and liquid fuel and air after cooling the liquid nozzle 10 are injected from the liquid fuel injection port 21. . Further, the liquid fuel nozzle 10 and the nozzle outer tube 22 are provided by a sealing block 30 ′ disposed between the natural gas nozzle 3 and the nozzle outer tube 22 and between the liquid fuel injection port 21 and the natural gas injection port 20. Is closed and only natural gas is injected from the natural gas injection port 20. The tip of the nozzle 29 is sealed with a conical block 31 '. The liquid fuel injection port 21 may use a general air atomization spray method using cooling air.

  FIG. 4 shows a fourth embodiment of the premixing nozzle. The premixing nozzle 5 of this embodiment is a general premixed combustor for natural gas in which a natural gas nozzle 3 is provided at the center of a cylindrical nozzle body 28 that forms a premixing chamber 27. Thus, the liquid fuel injection port 21 is disposed downstream of the swirler 4 and upstream of the natural gas injection port 20. Although not shown, the liquid fuel nozzle 10 may be covered with a nozzle outer tube as shown in FIG. 3 to cool the liquid fuel nozzle 10 with air. Further, the liquid fuel injection port 21 may use a general pressure swirl spray method or a general air atomization spray method. Reference numeral 19 in the figure denotes a wall that partitions the combustion chamber.

  FIG. 5 shows a fifth embodiment of the premixing nozzle. In the combustor of this embodiment, a non-premixing burner 32 for starting and flame holding is disposed on the central axis of the top portion of the inner cylinder 7 forming the combustion chamber 26, and the inner cylinder downstream of the non-premixing burner 32. The premixing nozzle 5 is disposed on the outer periphery of the nozzle 7 so as to inject the lean premixed gas. The non-premixed burner 32 includes a natural gas nozzle 3 ′ that injects a part of natural gas along the central axis, and a swirler 4 ′ that swirls combustion air from the periphery and introduces it into the combustion chamber 26. ing. The premixing nozzle 5 includes a swirler 4, a liquid fuel nozzle 10, and a natural gas nozzle 3 in this order. Liquid fuel is injected into combustion air that flows while swirling to form an air-fuel mixture. Is injected and injected as a premixed gas inward from the peripheral surface of the inner cylinder 7. That is, the liquid fuel injection port 21 is disposed downstream of the swirler 4 and upstream of the natural gas injection port 20. Although not shown, the liquid fuel nozzle 10 may be covered with a nozzle outer tube as shown in FIG. 3 to cool the liquid fuel nozzle 10 with air. Further, the liquid fuel injection port 21 may use a general pressure swirl spray method or a general air atomization spray method.

The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention. For example, in the above-described embodiment, from the viewpoint of reducing CO _{2 in} the gas turbine combustor, the case where dimethyl ether mainly produced from bioethanol or biofuel is used as the liquid fuel is mainly described. The gas turbine combustor of the present invention and the method of operating the same are not limited to these, as long as it is a liquid fuel that is completely vaporized at the temperature of combustion air supplied to the premixing nozzle or at a temperature lower than that It goes without saying that it can be used in Alcohol-based fuel, LPG, or dimethyl ether synthesized from low-grade fuel such as waste plastic, lignite, or super heavy oil may be used as the liquid fuel. In particular, by converting lignite, oil sand, oil shale, etc., which have abundant resources but are not yet used, to methanol and dimethyl ether and burn them in this gas turbine, these resources can be used efficiently and cleanly. be able to. By using dimethyl ether, which is synthesized from low-grade fuel such as waste plastic, lignite and super heavy oil, as a liquid fuel and co-firing with natural gas, it can be used more efficiently with higher energy efficiency than that used in boilers. And compared with boiler steam turbine power generation, the energy efficiency of gas turbine combined power generation is high, and as a result of reducing fuel consumption, the amount of CO ₂ produced can also be reduced. Similarly, when LPG, industrial alcohol, or the like is used as the liquid fuel, the amount of CO ₂ produced can be reduced when used in the gas turbine combined power generation as compared with the case where it is used in the boiler steam turbine power generation. In addition, when dimethyl ether produced using biomass as a raw material is used, a CO ₂ reduction effect associated with the use of biomass fuel is further added, and a large CO ₂ reduction effect is obtained.

  Further, in the above-described embodiment, the swirler 4 as a means for mixing the liquid fuel and the combustion air is preferable in order to reliably and quickly mix the liquid fuel and the combustion air. The swirler 4 may not be necessary if conditions for uniformly and sufficiently mixing the combustion air introduced into the fuel 27 and the liquid fuel can be set.

  Further, depending on the liquid fuel, when the supply is stopped, the liquid fuel remaining in the liquid fuel supply system 16 may not flow. Therefore, in such a gas turbine engine in which liquid fuel is used, by adding a mechanism for purging the liquid fuel supply system 16, the liquid fuel remaining in the pipe with the purge gas is removed when the supply of the liquid fuel is stopped. It is desired to eliminate problems such as clogging of piping due to residual liquid fuel by pushing to the premixing nozzle 5. The purge gas is preferably an inert gas such as steam or nitrogen. By injecting purge gas such as steam or nitrogen into the fuel nozzle through the fuel supply system when the operation is stopped, and cleaning up the liquid fuel remaining in the fuel supply system and the fuel nozzle, accidental blockage or the like can be prevented.

1 is a schematic configuration diagram illustrating a first embodiment of a gas turbine and a gas turbine power generation system according to the present invention. It is the schematic which shows one Embodiment of the structure of the premixing nozzle of this invention. It is the schematic which shows one Embodiment of the structure of the premixing nozzle of this invention. It is the schematic which shows one Embodiment of the structure of the premixing nozzle of this invention. It is the schematic which shows one Embodiment of the structure of the premixing nozzle of this invention. It is a figure which shows the relationship between the temperature of the main liquid fuel which can be used by this invention, and vapor pressure. When the main liquid fuel and natural gas that can be used in the present invention are used, the combustor inlet temperature is 400 ° C., the combustor outlet temperature is 1500 ° C., and the weight ratio of the liquid fuel to natural gas is changed, The fuel concentration of the premixed gas of the combustion air in the premixing nozzle and the vaporized liquid fuel is shown. When the main liquid fuel and natural gas that can be used in the present invention are used, the combustor inlet temperature is 400 ° C., the combustor outlet temperature is 1500 ° C., and the liquid fuel is ignited in the premix nozzle, The average temperature of the combustion gas upstream of the natural gas nozzle is shown.

Explanation of symbols

3 Gas fuel nozzle 4 Swirler 5 Premix nozzle 6 Outer cylinder 7 Inner cylinder 8 Liquid fuel tank 10 Liquid fuel nozzle 20 Gas fuel injection port 21 Liquid fuel injection port 24 Combustor 26 Combustion chamber 27 Premix chamber

Claims (5)

In a gas turbine combustor using a gas as a fuel and having a premixing nozzle that supplies a premixed gas in which the gas fuel is mixed with air to the combustor, the gas fuel is supplied as a main fuel under operating conditions higher than a load operation. However, an amount of liquid fuel that is completely vaporized at the temperature of the combustion air supplied to the premixing nozzle or at a temperature lower than that and has a concentration less than the lower limit of flammability with respect to the flow rate of the combustion air. the upstream of the injection port of the gas fuel with the injection port of the liquid fuel injected remain liquid in said stream of combustion air, completely the liquid fuel is mixed with the combustion air as subordinate fuel the mixed gas fuel after vaporized completely as lean premixed mixture of vaporized liquid fuel and the combustion air and the gas fuel from the premixed nozzles are supplied to the combustor is mixed combustion, Gas turbine combustor for generating combustion gases for driving the turbine. The gas turbine combustor according to claim 1, wherein the liquid fuel is an alcohol fuel. The gas turbine combustor according to claim 2, wherein the alcohol fuel is plant-derived bioethanol . The gas turbine combustor according to claim 1, wherein the liquid fuel is LPG or dimethyl ether . In a gas turbine combustor using a gas as a fuel and having a premixing nozzle that supplies a premixed gas in which the gas fuel is mixed with air to the combustor, the gas fuel is supplied as a main fuel under operating conditions higher than a load operation. However, an amount of liquid fuel that is completely vaporized at the temperature of the combustion air supplied to the premixing nozzle or at a temperature lower than that and has a concentration less than the lower limit of flammability with respect to the flow rate of the combustion air. The fuel is injected as a liquid upstream from the injection position of the gas fuel, and the liquid fuel is mixed with the combustion air and completely vaporized, and then mixed with the gas fuel and completely vaporized. A gas turbine operating method, wherein a lean premixed mixture of liquid fuel, combustion air and gas fuel is supplied from the premixing nozzle to the combustor and co-fired.

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