JPH06101808A - Premixing combustion device and combustion control thereof - Google Patents

Abstract

PURPOSE:To always maintain a NOx at a low level and stabilize a flame by a method wherein fuel and/or air volume is controlled in such a manner that a composition of fuel flowing into a burner, a moisture concentration of air, a temperature of air and a flame temperature calculated in response to an air ratio are set to be within an allowable range. CONSTITUTION:At a basic control device, a flame temperature of each of burners is calculated in response to an air temperature, humidity, pressure, flow rate, composition of fuel and moisture content in fuel. Then, a flow rate, fuel distribution and air flow rate distribution are corrected when it is judged that a flame blowing-off occurs or a concentration of discharged NOx exceeds its limit value in reference to a function 1 in which a relation between the flame temperature and the NOx discharging concentration is set as a function, a function 2 in which a fuel composition and the NOx discharging concentration variation is set as a function, and a function 3 in which a relation between the flame temperature where the flame is blown off and an injection speed of the mixture gas is set as a function. With such an arrangement as mentioned above, the variation of the discharging amount of NO2 caused by the surrounding air temperature, humidity and variation of composition of the fuel and the like is minimized and a stable flame with a low NOx can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a premixed combustion device and a combustion control method therefor. The present invention also relates to a gas turbine power generator. The combustion device of the present invention can also be applied to a boiler. INDUSTRIAL APPLICABILITY The present invention is particularly suitable for being applied to a gas turbine power generator using a gas fuel or a liquid fuel or a combustor thereof.

[0002]

2. Description of the Related Art Instead of diffusive combustion, in which fuel and air are supplied from different jet ports and mixed and burned in a combustion chamber,
Premixed combustion, in which fuel and air are premixed and then burned, is being used.

By using premixed combustion, the reaction region of combustion can be reduced, that is, the flame can be shortened and high load combustion can be performed. Further, the NOx emission amount can be reduced by using the lean fuel premix combustion method. Such a lean premixed combustion method is being adopted in a gas turbine combustor or the like.

One problem with premixed combustion is that the flow velocity range in which flames can be stably formed is narrow, and flashback and blowout easily occur. Therefore, in a combustor such as a gas turbine combustor in which the combustion amount changes greatly from startup to maximum load, the fuel-air mixture ratio is kept within a certain range in which the NOx emission amount is low even if the load changes. There is a need for such an air flow rate control mechanism. For example, in the combustor described in U.S. Pat. No. 4,150,539, a method is proposed in which the flame stabilizer is moved in the axial direction of the combustor to control the air flow rate.

By doing so, a stable premixed flame is always formed even if the load of the gas turbine changes, and NO
It is possible to reduce x emissions. However, the stability of the premixed flame and the NOx emission amount are also affected by the humidity and temperature in the atmosphere, the temperature of the combustion air, the properties of the fuel, and the heat generation amount. For example, when the humidity in the atmosphere is high, the NOx emission amount is small, but the flame stability is reduced and the misfire tends to occur. To cope with such changes in atmospheric humidity,
Japanese Patent Laid-Open No. 2-33419 describes a method of detecting atmospheric humidity and changing the amount of air supplied to the premix combustion burner based on this detection signal. However, it is not stated quantitatively how much the amount of air should be changed with respect to changes in atmospheric humidity, nor is there a method for quantitatively obtaining the amount of changes in air with respect to changes in atmospheric humidity. Since the atmospheric humidity varies considerably depending on the season and region, how to control the amount of air against changes in atmospheric humidity depends on each gas turbine device, each season, and each region where it is installed. It must be decided based on the driving results. Further, since JP-A-2-33419 does not describe a method of coping with a change in fuel heat generation amount, it is not possible to determine how much the air amount should be changed when the atmospheric humidity and the fuel heat generation amount change at the same time. .

[0006]

As described above, in the prior art, since the stability of the premixed flame and the NOx emission amount change due to the change in atmospheric humidity, the air ratio of the premixed flame changes according to the change in atmospheric humidity. Although it was recognized that it was necessary to do so, it was not known quantitatively how much the air ratio should be changed. Also, no method for quantitatively grasping the air ratio change amount has been presented. Further, no consideration was given to the control method when the atmospheric humidity and the fuel composition and the like change at the same time.

An object of the present invention is to minimize changes in NOx emissions due to changes in atmospheric temperature, humidity, fuel composition, etc., and to always maintain low NOx and maintain good flame stability. A combustion control method is provided.

[0008]

SUMMARY OF THE INVENTION The present invention is a combustor having a premixed combustion burner for ejecting a mixed flow of fuel and air to form a complete combustion flame, the composition of the fuel and the air flowing into the burner. And / or fuel supplied to the burner so that the flame temperature calculated by calculation from the water concentration and the air temperature and air ratio falls within a preset allowable range.
Alternatively, it is to control the amount of air.

As described above, in the prior art, when the atmospheric humidity, temperature and fuel composition were changed at the same time, it was difficult to maintain an optimum combustion state with low NOx and good flame stability. This is because the combustion state of the flame is judged based on the mixture ratio of fuel and air.

On the other hand, the present invention intends to judge the combustion state of the flame based on the flame temperature calculated. As this flame temperature, it is particularly desirable to find the adiabatic flame temperature. The adiabatic flame temperature means the maximum flame temperature obtained by calculation. For adiabatic flame temperature, see LDSmoot and DTPratt, Pulverized-Coal
Combustion and Gasification, PLENUM PRESS, New York
(1979) and S. Gordon and B. McBride, Computer Program f
or Calculation of Complex Chemical Equilibrium Comp
osition, NASA SP-273 (1971).

The present inventors have found that in premixed combustion with excess air, particularly preferably in premixed combustion with an air ratio of 1.0 or more and 2.2 or less, the composition of the fuel flowing into the burner, the water concentration of air, and the air content. The flame temperature calculated from the temperature and the air ratio is the NOx concentration and CO concentration discharged from the combustor,
Or, it was found that it has a very good correlation with the flame blowout limit, the oscillating combustion occurrence limit, and the flame flashback limit,
The present invention has been discovered. The calculated values of adiabatic flame temperature show the best correlation with these properties.

How the inventors of the present invention have made a study will be described.

[I] If the fuel composition and flame temperature are the same, the NOx emission amount is almost the same even if the air ratio, the air-fuel mixture temperature before combustion, and the water concentration in the air-fuel mixture change.

[Ii] The influence of the fuel composition on the NOx emission amount when the flame temperature is the same, the main component of the fuel and the calorific value of the fuel, the main component of the fuel and the average carbon number in one molecule of the fuel, or It can be almost determined if the physical quantity that can specify any of these quantities is known. Generally, when the average carbon number in one molecule of fuel increases, the NOx emission amount increases monotonously.

[Iii] If the jet speed of the mixed gas is almost the same, the flame temperature at which the flame blows off will change even if the fuel composition, the water content in the mixed gas, and the mixed gas temperature before combustion change. It is almost the same.

[Iv] If the jet speed of the mixed gas is almost the same, the flame temperature at which oscillatory combustion occurs even if the fuel composition, the water content in the mixed gas, and the mixed gas temperature before combustion change Are almost the same.

[V] If the jet speed or the air flow rate of the mixed gas is almost the same, the fuel composition, the water concentration in the mixed gas,
Also, even if the temperature of the air-fuel mixture before combustion changes, the flame temperature when the amount of CO emission rapidly increases is almost the same.

From the above, whether or not the combustion state is optimal even if the atmospheric humidity, temperature and fuel composition change at the same time,
It is possible to immediately determine what kind of operation should be performed in order to keep the combustion state optimum. If the changes over time in atmospheric humidity, temperature, and fuel composition can be predicted, it is possible to know in advance the amount of fuel and the amount of air required to keep the combustion state optimum.

As a concrete combustion state control method, for example, the following method is possible.

(A) Under each load, the allowable range of the optimum flame temperature at which a NOx emission concentration is low and a flame with good stability is formed is input in advance to the control device, and the humidity and temperature of the combustion air are set. , And the amount of fuel and / or air supplied to the burner is controlled so that the temperature change of the flame falls within an allowable range when the fuel composition changes.

(B) Relation between NOx emission concentration and flame temperature, relation between NOx concentration change rate emitted from flame and fuel calorific value or average carbon number in one molecule of fuel when flame temperature is constant, and , When the flame is blown out, when vibration occurs, and when CO is generated, the relationship between the flame temperature and the jetting speed of the mixed gas of fuel and air or the flow rate of the mixed gas is made into a function and input to the control device in advance. , Referring to these functions, NOx emission concentration is low, and the flame is extinguished,
The amount of fuel and / or the amount of air supplied to the burner is determined according to the load so that vibration or generation of CO does not occur.

[0022]

The present invention is to judge and control the combustion state of the flame based on the calculated value of the flame temperature. The aim of flame combustion control is to reduce NOx emission concentration or CO emission concentration, to prevent blowout of flame, and to prevent vibration or flashback. According to the present invention, the flame temperature is obtained by calculation based on the composition of the fuel flowing into the premixed combustion burner, the moisture concentration of air, the temperature of air and the air ratio, and the combustion state is controlled based on this flame temperature. Even if the atmospheric humidity, temperature, and fuel composition change, the NOx emission concentration and CO emission concentration can be constantly lowered, and the combustion state can be controlled so that flame blowout, vibration, or flashback does not occur.

When obtaining the relationship between the combustion state and the calculated flame temperature, it is desirable to take the composition of the fuel and the calorific value into consideration.

The flame to be controlled is a premixed flame in which fuel and air are premixed and then burned. The fuel used may be either a gas or a liquid, and the gas fuel is L
NG, LPG, city gas, etc. can be used, and as the liquid fuel, methanol, naphtha, ethanol, kerosene, light oil, etc. can be used. In any case, it is desirable to use a fuel containing almost no nitrogen in the molecule. Maximum nitrogen content is 1%
It is desirable not to exceed.

According to the present invention, by using the relationship between the rate of change of NOx concentration discharged from the flame and the calorific value of the fuel or the average number of carbon atoms in one molecule of fuel when the flame temperature is constant, the denitration device can be used. It is also possible to control the amount of ammonia supplied.

In the gas turbine power generator of the present invention, an air compressor, a high-pressure air supplied from the air compressor and a combustor for combusting fuel, and a fuel and air provided in the combustor are mixed in advance. A premixed combustion type burner that performs post-combustion, a gas turbine that is driven by the combustion gas discharged from the combustor, and that is connected to the air compressor, and a control command to the combustor according to the load fluctuation of the turbine And a generator connected to the turbine, and further has a control device for controlling the fuel supply amount or the air supply amount of the burner based on the adiabatic flame temperature.

In order to control the fuel supply amount or the air supply amount of the burner based on the adiabatic flame temperature, it is assumed that the temperature, the humidity, and the fuel calorific value of the combustion air flowing into the burner have certain representative values. The control section of the central operating room is equipped with a program relating the turbine load and the amount of air supplied to the premixed combustion burner, and the turbine load and the optimum combustion temperature in the premixed combustion burner at this time. Good.

Alternatively, the load of the turbine and the amount of air supplied to the premix combustion burner, and the load of the turbine and the premix are presumed assuming that the temperature, the humidity, and the calorific value of the fuel of the combustion air are representative values. A program that relates the amount of fuel supplied to the combustion burner is provided. Furthermore, a program that relates the amount of air supplied to the premixed combustion burner and the flame temperature at which the flame blows out at that time, the flame temperature at the premixed combustion burner, and At least one of a program relating the NOx emission concentration at this time and a program relating the NOx emission concentration and the fuel composition burned in the premixed combustion burner when the flame temperature is constant to the control section of the central operating room. It may be provided.

Further, the required load of the turbine and the amount of air supplied to the premixed combustion burner, and the required load and the precondition of the turbine, assuming that the temperature, the humidity, and the calorific value of fuel of the combustion air have certain representative values. Relationship between the program relating the amount of fuel supplied to the mixed combustion burner, the required load of the turbine and the range of the combustor outlet temperature at which the NOx emission concentration is below the limit value and the misfire of the premixed combustion burner does not occur The attached program may be provided in the control section of the central operation room.

As a control method of the gas turbine power generator, the gas temperature at the inlet of the gas turbine under the actual moisture concentration in the air supplied during the operation of the gas turbine, the temperature, and the calorific value of the fuel are supplied. A control method that changes the fuel supply amount so as to reduce the temperature difference between the gas turbine inlet gas temperature when assuming that the water moisture concentration in the air, the temperature, and the calorific value of the fuel have certain representative values is effective. Is.

Alternatively, the adiabatic flame temperature formed by the premixed combustion burner based on the water concentration, temperature and fuel heating value in the actual air supplied during the operation of the gas turbine, and the Compare the moisture concentration, temperature, and the adiabatic flame temperature formed by the premixed combustion burner assuming that the representative value is a certain value, and supply to the premixed combustion burner so that the temperature difference between the two becomes smaller. A control method that changes the amount of fuel and / or the amount of air that is discharged is effective.

By thus diagnosing the combustion state and displaying the result of control on the display in the central operation room, it is possible to give an appropriate instruction to the operator.

When one gas turbine is provided with a plurality of combustors, means for individually detecting the amount of air flowing into each combustor or means for individually detecting the combustion temperature in each combustor. By providing the, it is possible to correct the variation in the combustion temperature among the combustors.

When the combustion control method of the present invention is used for a combustor provided with a flow path resistor against which a jet of mixed gas of fuel and air collides as means for forming a premixed flame with a premix burner, Since the temperature change of the premixed flame that heats the resistor is small, the flow path resistor is not heated rapidly,
Longer life.

Further, in the method for operating the gas turbine power generation equipment of the present invention, when the premixed flame formed in the combustor is operated so that the adiabatic flame temperature is 1650 K or higher and 1970 K or lower, the premixed flame is not misfired. In addition, the NOx emission amount can be reduced to the level where the denitration device is unnecessary.

The present invention can also be applied to a combustor having a premix combustion burner and a diffusion combustion burner.

An invention for controlling the supply amount of fuel gas or combustion air based on the predicted value of flame temperature has been made in a hot stove, and is disclosed in Japanese Patent Laid-Open No. 63-65230. However, the present invention does not consider air humidity at all.

[0038]

Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment 1] FIG. 1 is a system diagram of a gas turbine power generator according to an embodiment of the present invention.

The fuel is supplied from the fuel tank 39, vaporized by the vaporizer 72, and sent to the fuel supply pipe 71. After the flow rate of the fuel is controlled by the fuel flow rate control device 64, the fuel is sent to the gas turbine combustor 21. The fuel calorific value is measured by the fuel calorific value measuring apparatus 1, and the fuel flow rate is measured by the fuel flow rate measuring apparatus 2. Here, when the fuel used is a fuel having a low boiling point such as LNG, a part of the fuel is vaporized in the fuel tank and the pressure in the fuel tank rises. At this time, in order to prevent the destruction of the fuel tank, the pressure in the tank is measured by the fuel tank pressure measuring device 43, and when the pressure in the tank exceeds the limit value, the fuel tank pressure adjustment valve 12 is opened and the gas in the tank is opened. Is discharged to the fuel supply pipe 71. The gas vaporized in the tank has many components with a low boiling point and differs from the composition of the fuel that is normally supplied. Therefore, when the pressure adjustment valve 12 in the fuel tank is opened, the fuel composition and the calorific value fluctuate.

When the fuel used is a water-soluble fuel such as methanol, the water content in the fuel affects flame stability and NOx emission concentration. At this time, the device 19 for measuring the water content in the fuel is required. When using methanol, light oil or the like as fuel, the tank pressure measuring device 43, the tank pressure adjusting valve 12, and the carburetor 72 are not necessarily required.

The flow rate of the air 32 is measured by the air flow rate measuring device 7,
After the temperature and humidity are measured by the atmospheric temperature and humidity measuring device 8, the high pressure air 33 is drawn into the air compressor 24. The high-pressure air 33 is sent to the gas turbine combustor 21 after its pressure is measured by the air pressure measuring device 5 and its temperature is measured by the gas turbine combustor inlet gas temperature measuring device 6. If the amount of air taken into the air compressor 24 can be calculated from the atmospheric temperature and humidity and the characteristics of the air compressor 24,
The air flow rate measuring device 7 is not always necessary when the air compressor 24 is provided with the control device 65 that keeps the amount of air taken in constant.

The gas turbine combustor has an outer cylinder 22 and an inner cylinder 23.
And high pressure air 3 between the outer cylinder 22 and the inner cylinder 23.
3 flows, and the premixed combustion burner 59 is used as combustion air 58.
Is supplied to. A part of the high pressure air 33 is the inner cylinder cooling air 5
6 is supplied to the combustion chamber 61. A diluted air amount control device 42 is provided downstream of the combustion chamber 61. When the load on the gas turbine is small, part of the combustion air 58 is discharged to the downstream side of the combustor as diluted air 57. The fuel is supplied from the fuel nozzle 40, mixed with the combustion air 58, and then combusted in the premixed combustion burner 59. The flame stabilizer 6 is provided by the action of the flame stabilizer 60 provided in the premixed combustion burner 59.
A circulating stream of hot gas is formed downstream of 0 and the heat from this circulating stream stabilizes the premixed flame. The gas generated from the premixed flame is the inner cylinder cooling air 56 and the diluted air 57.
Is mixed with high-temperature combustion gas to be introduced into the gas turbine 25 through the transition piece. Gas turbine 2
5 and the air compressor 2 connected to the gas turbine 25
4, and the high-temperature combustion gas 34 that has driven the generator 26 becomes low-temperature combustion exhaust gas 35 and is guided to the flue gas denitration device 28. The nitrogen oxides in the low temperature combustion exhaust gas 35 react with ammonia in the flue gas denitration device 28 and are converted into nitrogen. Ammonia is supplied from the ammonia tank 29, the flow rate is controlled by the ammonia flow rate control device 70, the flow rate is measured by the ammonia flow rate measuring device 15, and then the flue gas denitration device 2
8 is supplied.

The low temperature combustion exhaust gas 35 is also guided to the waste heat recovery boiler 30. The steam turbine 27 is driven by the steam 36 generated in the waste heat recovery boiler 30. This steam turbine 27 is also connected to the generator 26. The steam 36 that has driven the steam turbine 27 is converted into water 3 in the condenser 31.
7, and the waste heat recovery boiler 30 is supplied again. Here, the positions of the waste heat recovery boiler 30 and the flue gas denitration device 28 may be reversed. The combustion exhaust gas 35 is the waste heat recovery boiler 30.
After that, the gas is mixed with the exhaust gas 69 from another gas turbine in the chimney 38 and is discharged into the atmosphere.

In the gas turbine of FIG. 1, the fuel supply amount according to the load, the distribution ratio of the fuel supply amount supplied to each burner, the distribution of the fuel air 58 and the diluted air 57, the flue gas denitration device 2
It is necessary to control the amount of ammonia supplied to No. 8. These flow rates and flow rate distributions are determined in the central operating room (not shown) according to the load request signal, and the fuel flow rate control signal, the fuel flow rate distribution control signal, the air flow rate distribution control signal, and the ammonia flow rate control signal are sent to the respective flow rate control devices. Be controlled.

FIG. 2 is a diagram showing a combustion control method in the gas turbine combustor 21 and a control method of the flue gas denitration device 28 when the gas turbine power generation facility of FIG. 1 is used. The flow rate of fuel supplied to the combustor, the fuel flow rate distribution to each burner, and the air flow rate distribution of air and diluted air supplied to each burner are determined by the basic control device based on the load demand. The basic control device determines the fuel flow rate, the distribution, and the air flow distribution based on the basic control plan input in advance. The basic control plan has air temperature, humidity, pressure, flow rate, fuel composition, water content in the fuel, etc. When there are planned values, the air flow rate distribution of the air supplied to each burner and the diluted air to the gas turbine load, The fuel flow rate supplied to the combustor and the fuel flow rate distribution to each burner are entered. When the air temperature, humidity, pressure, flow rate, fuel composition, and water content in the fuel are all the same as the planned values, the fuel flow rate, distribution, and air flow distribution should be determined according to the basic control plan. NO
x It is necessary to correct the fuel flow rate, distribution, and air flow distribution so that the emission concentration is below the limit value and flame misfire does not occur. The control device of the present invention includes a function that functionalizes the relationship between the flame temperature and the NOx emission concentration, a function that functionalizes the relationship between the fuel composition and the NOx emission concentration change, and the flame temperature and the mixed gas at which the flame blows out. A function 3, which is a function of the relationship of the ejection speed of, is input in advance, and the fuel flow rate, the distribution, and the air flow distribution are corrected based on these functions 1, 2, and 3. The corrected fuel flow rate, distribution, and air flow distribution are output to each control device. It is also output to the ammonia flow rate control device. The basic control device is controlled so that the flame temperature is kept almost constant even if the air temperature, humidity, fuel composition, and water content in the fuel are changed so that a stable flame with low NOx emission concentration is formed. It However, even if the flame temperature is constant, the NOx emission concentration changes depending on the fuel composition, so it is necessary to control the ammonia flow rate according to the change in the fuel composition. In the ammonia flow control device, the flame temperature output from the basic control device, the fuel composition and NOx when the flame temperature is constant.
The ammonia supply amount is determined based on the function 2, which is a function of the relationship with the emission concentration change.

FIG. 3 shows the basic control device for the fuel flow rate, distribution,
It is a figure which shows the method of determining air flow distribution. First, based on the load demand, the fuel flow rate, distribution, and air flow rate distribution of the basic control plan are output. Next, the flame temperature of each burner is calculated based on the measurement results of the air temperature, humidity, pressure, flow rate, fuel composition, water content in fuel, and fuel flow rate, distribution, and air flow distribution in the basic control plan. Next, referring to the functions 1, 2, and 3, when the fuel flow rate, the distribution, and the air flow distribution are set to the basic control plan values, it is determined whether the flame blows out or the NOx emission concentration does not exceed the limit value. . When it is determined that the flame is extinguished or the NOx emission concentration exceeds the limit value, the fuel flow rate, distribution, and air flow distribution are corrected. Next, the flame temperature is calculated based on the corrected fuel flow rate, distribution, air flow rate distribution and air temperature, humidity, pressure, flow rate, fuel composition, and water content in the fuel, and the function 1,
Refer to 2 and 3 to see if the flame is blown out or NOx
Determine whether the emission concentration does not exceed the limit value. By repeating such operations, it is determined that the flame does not blow out and the NOx emission concentration does not exceed the limit value, and then the determined fuel flow rate, distribution, and air flow distribution are output. The fuel flow rate,
The distribution and the correction of the air flow rate may be corrected for only one of them or for all of them.

4 to 7 show examples of the functions 1, 2 and 3. Although it is shown here in the form of a graph, it may be inputted in the form of a mathematical expression or a numerical value in the control device.

FIG. 4 is an example of the function 1, and is a diagram showing the relationship between the adiabatic flame temperature and the NOx emission concentration in each burner. The allowable upper limit of the NOx emission concentration at each burner is input to the function 1 in advance. In addition, a certain representative property is specified for the fuel composition. Here, the heat generation amount is designated as a representative property.

FIG. 5 is an example of the function 2, and is a diagram showing the relationship between the fuel heat value and the NOx emission concentration when the flame temperature is constant. Here, the abscissa represents the ratio of the calorific value of the representative property value to the actual calorific value, and the ordinate represents the NOx emission concentration ratio.

Air temperature, humidity, pressure, flow rate, fuel composition,
The adiabatic flame temperature at each burner can be calculated from the measurement results of the water content in the fuel and the fuel flow rate, distribution, and air flow distribution. Based on the calculation result of the adiabatic flame temperature, based on Fig. 4, NOx
It is possible to determine whether the emission concentration is below the allowable limit. When the fuel heat generation amount is different from the representative property value, the NOx emission concentration obtained from FIG. 4 is corrected using FIG.

6 and 7 are examples of the function 3. FIG. 6 is a diagram showing the relationship between the ejection speed at each burner and the adiabatic flame temperature at which blowout occurs. Air temperature, humidity, pressure,
Since the adiabatic flame temperature and ejection speed at each burner can be obtained from the measurement results of the flow rate, the fuel composition, the water content in the fuel and the fuel flow rate, distribution, and air flow distribution, it is determined from FIG. 6 whether the flame is misfired or not. Can be determined. Note that the horizontal axis in FIG. 6 may use the diluted air amount ratio, the amount of air supplied to each burner, the opening of the air flow rate control device, or the like instead of the ejection speed.
FIG. 7 is an example showing the relationship between the diluted air amount ratio and the adiabatic flame temperature at which the burner blows off at this time.

FIG. 8 shows a basic control system for fuel flow rate, distribution,
It is a figure which shows the other example of the method of determining air flow distribution.
Here, the functions 1, 2, and 3 are not used, but instead, the adiabatic flame temperature at each optimum burner at each load of the gas turbine and the allowable range of the adiabatic flame temperature are input in advance during the basic control plan. If the adiabatic flame temperature is within the permissible range, flame blowout does not occur and the NOx emission concentration is low.

In this method, first, the fuel flow rate, distribution, and air flow distribution are output from the basic control plan according to the load demand. It also outputs the allowable range of the optimum flame temperature and the adiabatic flame temperature. Next, the adiabatic flame temperature of each burner is calculated based on the measurement results of the air temperature, humidity, pressure, flow rate, fuel composition, fuel water content, fuel flow rate, distribution, and air flow distribution, and the allowable adiabatic flame temperature is calculated. Compare with the range. As a result of the comparison, when it is determined that the calculation result of the adiabatic flame temperature exceeds the allowable range, the fuel flow rate, the distribution, and the air flow rate distribution are corrected, and the adiabatic flame temperature is calculated based on the correction result.
This operation is repeated so that the calculation result of the adiabatic flame temperature is within the allowable range, and the fuel flow rate distribution and the air flow rate distribution are output.

When the combustor 21 is provided with a diffusion combustion burner and a premixed combustion burner, it is desirable to control as shown in FIG. That is, according to the load demand, the air flow rate distribution and the fuel flow rate distribution are output from the basic control plan. Further, the optimum gas turbine outlet temperature and the allowable range of the gas turbine outlet temperature at this time are output. In the arithmetic unit, based on the measurement results of air temperature, humidity, pressure, flow rate, fuel composition, and water content in fuel,
The fuel flow rate is determined and output so that the gas turbine outlet temperature matches the optimum temperature output from the basic control plan or is within the allowable range. With this method, air flow distribution,
Since the fuel flow distribution is not changed, the flame temperature of each burner changes in the same manner by adjusting the fuel flow. Therefore, if the fuel flow rate is determined so that the gas turbine outlet temperature becomes the optimum value, the flame temperature of each burner also becomes the optimum value. This control method is characterized in that the combustion state can be controlled so that the flame temperature of each burner is maintained at an almost optimum state even if the amount of air supplied to each burner is not exactly known.

It is desirable that the allowable range of the adiabatic flame temperature and the calculated value are output to the display in the central operation room.
FIG. 10 is an example of the result output to the display,
4 is an example when the gas turbine power generator shown in Example 1 is used. The relationship between the opening of the air flow control valve, the flame temperature when the flame blows off at that time, the flame temperature when the NOx emission amount exceeds the reference value, and the flame temperature under the optimum operating condition is shown. Also, the current operating state is shown. In this case, the flame temperature is slightly lower than the optimum value in the current operating condition, and in order to achieve the optimum operating condition, the fuel supply amount is increased to increase the flame temperature or the opening degree of the air flow control valve is increased. It turns out that it needs to be increased.

In addition, it is also desirable to display the relationship between the required load and the optimum gas turbine outlet temperature for the required load. Of course, it is not limited to these.

[Embodiment 2] FIG. 11 is a method for predicting changes over time in air humidity, fuel heating value, and gas turbine load using the gas turbine power generator of Embodiment 1 and controlling the combustion state based on the prediction results. Is an example. First, the changes over time in air humidity, fuel calorific value, and gas turbine load are measured and input to the temperature, calorific value, and load change prediction device. The temperature, heat value, load change prediction device uses the measurement results, past operation data, and factors that affect temperature, heat value, load changes, such as fuel tank pressure and weather forecast, to predict future air humidity. Predict changes over time in fuel calorific value and gas turbine load. This prediction result is input to the basic control device, and the basic control device refers to the functions 1, 2, 3 and the basic control plan based on the input result, and predicts the air flow distribution, the fuel flow distribution, and the fuel supply amount prediction result. Is output.

By predicting the operating state in advance in this manner, it is possible to quickly follow a sudden change in the fuel heat generation amount or the like.

By using the gas turbine power generator of the present invention, changes in NOx emissions due to seasonal changes, fuel composition changes, installation areas, etc. are minimized, and low NOx is always maintained and flame stability is kept good. Will be possible. As a result, the amount of ammonia used in the denitration device installed in the gas turbine power generation facility can be reduced. However, if the gas turbine power generation device of the present invention is used and the combustion state is accurately controlled, the denitration device can be eliminated. . Generally, in order to eliminate the need for a denitration device, NO emitted from a gas turbine combustor
It is said that the x concentration needs to be 10 ppm or less in terms of 16% O ₂ .

FIG. 12 is a diagram showing an example of the relationship between the adiabatic flame temperature and the NOx concentration, and FIG. 13 is a diagram showing the relationship between the adiabatic flame temperature and the ejection speed. All are the results measured under atmospheric pressure. It is said that the NOx concentration generally increases in proportion to the power of 0.5 of the pressure, and the combustion pressure in the gas turbine power generator is generally about 10 to 16 atm. To reduce the NOx concentration to 10 ppm or less when the combustion pressure is 10 atm, the NOx concentration at atmospheric pressure should be approximately 3.2 ppm or less, and the NOx concentration at 16 atm should be 10 ppm or less at atmospheric pressure. It is necessary to keep the NOx concentration at about 2.5 ppm or less. Based on the result of FIG. 12, the combustion pressure is 10
Considering the condition that the NOx concentration is 10 ppm or less under 16 atm, it is necessary to set the adiabatic flame temperature to about 1890 to 1970 K or less, although it varies depending on the combustor. On the other hand, when the adiabatic flame temperature becomes 1650 to 1720K or lower, the flame blows off regardless of the ejection speed. Therefore,
It is considered that maintaining the adiabatic flame temperature of the premixed flame provided in the gas turbine combustor between about 1650 and 1970K is an operating condition necessary for eliminating the denitration device.

An example of the experimental results that have led to the present invention will be described below. FIG. 14 shows an air preheating temperature of 29
8K to 667K, air ratio 0.7 to 1.9, air humidity 0.
[0094] The experimental results obtained by changing the ejection speed in the range of 5 to 12 n / s at 0.023 kg / kg and the adiabatic flame temperature and NO
x It is arranged in relation to the emission concentration. The numbers indicated by arrows at the measurement points in the figure are air ratios. The air ratio at the measurement points without numbers is 1.2 to 1.9. Regarding the excess air flame with an air ratio of 1.05 or more, when the same fuel is used, if the flame temperature is the same, the NOx concentration is almost the same even if the air preheating temperature, air ratio, and air humidity are different. is there. That is, if the combustion state is controlled so as to keep the flame temperature constant, the NOx concentration can always be kept low even if the air preheating temperature, the air ratio, and the air humidity change.

However, in a flame with an air ratio of 1.0 or less,
Since there is no correlation between the maximum flame temperature and the NOx concentration, the above combustion state control method is effective when forming a flame with excess air.

In FIG. 14, methane and propane were used as fuels. As can be seen from the figure, even if the flame temperature is constant, the NOx concentration changes if the fuel properties are different. NOx is easily emitted from a propane flame, and when compared at the same flame temperature, it is about 2 times less than the NOx concentration from a methane flame.
5% higher. Further, in order to make the NOx concentration from the methane flame the same, it is necessary to lower the flame temperature by 30 to 40K.

FIG. 15 shows NOx when the fuel composition is changed.
It is the result of arranging the concentration by the average carbon number in one molecule of fuel. The NOx concentration from the ethane flame is almost the same as when the methane-propane mixed fuel having the same average carbon number is used, as in the case of sorting by the fuel calorific value. from this result,
It can be understood that the NOx concentration when the fuel composition is changed with the flame temperature kept constant can be almost determined by knowing the fuel calorific value or the average number of carbon atoms in one molecule of fuel, even if the fuel composition is unknown.

FIG. 16 shows the relationship between the CO emission concentration and the air ratio measured by changing the air preheating temperature, the air humidity, and the fuel composition. CO is not emitted from any of the flames when the air ratio is around 1.2, but when the air ratio exceeds a certain level, CO is not emitted.
The emission concentration rises sharply. However, the air ratio at which the CO emission concentration sharply rises differs depending on the difference in air preheating temperature, air humidity, and fuel composition.

FIG. 17 shows the results of FIG. 16 arranged by adiabatic flame temperature. The flame temperature when the CO emission concentration rapidly increases is almost constant regardless of the difference in air preheating temperature, air humidity, and fuel composition. When the fuel composition is the same, the absolute value of CO emission concentration can be almost determined if the flame temperature is known.

FIG. 18 summarizes the relationship between the adiabatic flame temperature at which oscillatory combustion occurs and the ejection speed. Similarly to the blowout limit shown in FIG. 13, the oscillating combustion generation conditions can be summarized by one curve for each combustor when arranged by flame temperature.

The following conclusions can be obtained by summarizing the above results.

(A) For a premixed flame using the same combustor, burner, and flame holding means with an air ratio of 1.05 or more, when the combustion state is sorted by flame temperature, CO generation conditions, blowout conditions, and oscillating combustion The generation condition of does not depend on the fuel composition, air humidity, and preheating temperature, and is almost fixed. If the calorific value of the fuel or the average number of carbon atoms in one molecule of the fuel is known, the NOx emission concentration is almost fixed.

(B) Therefore, if the amount of fuel and / or the amount of air supplied to the burner is controlled so that the flame temperature does not change even if the fuel composition, air humidity, and preheating temperature change, the flame blows out and CO Neither generation nor oscillatory combustion occurs.
Further, the change in NOx emission concentration due to the change in fuel composition can be minimized.

(C) The influence of the calorific value of the fuel or the average number of carbon atoms in one molecule of fuel on the NOx emission concentration when the flame temperature is constant is known, and the combustion state is controlled as shown in (b). First, the NOx emission concentration is determined by detecting the change in the calorific value of the fuel or the average carbon number in one molecule of the fuel. Therefore, the amount of ammonia supplied to the flue gas denitration device is also determined.

[0073]

According to the present invention, changes in NOx emissions due to changes in atmospheric temperature, humidity, fuel composition, etc. are minimized and low N
It is Ox and can maintain good flame stability.

[Brief description of drawings]

FIG. 1 is a system diagram of a gas turbine power generator according to a first embodiment.

FIG. 2 is a conceptual diagram showing a method for controlling combustion in a gas turbine combustor and a method for controlling a flow rate of ammonia supplied to a denitration device.

FIG. 3 is a diagram showing an example of a method of determining a fuel flow rate, a fuel distribution, and an air flow distribution to be supplied to a gas turbine combustor in a control device which is the basis of the present invention.

FIG. 4 is a view showing an example of a function that is a function of the relationship between the flame temperature and the NOx emission concentration, which is input to the control device.

FIG. 5 is a diagram showing an example of a function input to the control device, which is a function of the relationship between the NOx emission concentration change and the fuel heat generation ratio when the flame temperature is constant.

FIG. 6 is a diagram showing an example of a function that is a function of the relationship between the ejection speed and the flame temperature at which blowout occurs, which is input to the control device.

FIG. 7 is a diagram showing an example of a function that is a function of the relationship between the diluted air amount ratio and the flame temperature at which blowout occurs, which is input to the control device.

FIG. 8 is a diagram showing another example of a method for determining a fuel flow rate, a fuel distribution, and an air flow distribution to be supplied to a gas turbine combustor in a control device according to another example of the present invention.

FIG. 9 is an example of a method for determining a fuel flow rate, a fuel distribution, and an air flow distribution to be supplied to a gas turbine combustor in a basic control device when a gas turbine power generator including a combustor having a diffusion combustion burner is used. FIG.

FIG. 10 is a diagram showing an example of a method for displaying a combustion diagnosis result.

FIG. 11 is a conceptual diagram showing an example of a method for predicting changes in gas turbine load, air humidity, and fuel calorific value, and controlling the combustion state.

FIG. 12 is a diagram showing a relationship between adiabatic flame temperature and NOx emission concentration.

FIG. 13 is a diagram showing the relationship between adiabatic flame temperature and ejection speed.

FIG. 14 is a diagram showing the relationship between the flame temperature of a premixed flame and the NOx emission concentration.

FIG. 15 is a graph showing the relationship between the average number of carbon atoms in one molecule of fuel and the NOx emission concentration when the flame temperature of the premixed flame is constant.

FIG. 16 is a diagram showing the relationship between the air ratio of premixed flame and the CO emission concentration when the air temperature, humidity, and fuel composition are different.

FIG. 17 is a diagram showing the relationship between the flame temperature of a premixed flame and the CO emission concentration.

FIG. 18 is a diagram showing the relationship between the ejection speed and the flame temperature at which oscillating combustion occurs at different air temperatures, humidity, and fuel compositions.

[Explanation of symbols]

1 ... Fuel calorific value measuring device, 2 ... Fuel flow rate measuring device, 5 ...
Air pressure measuring device, 6 ... Gas turbine combustor inlet gas temperature measuring device, 7 ... Air flow measuring device, 8 ... Atmospheric temperature and humidity measuring device, 15 ... Ammonia flow measuring device, 19 ...
Device for measuring water content in fuel, 21 ... Gas turbine combustor, 24 ... Air compressor, 25 ... Gas turbine, 26 ... Generator, 27 ... Steam turbine, 28 ... Denitration device, 39 ... Fuel tank, 40 ... Fuel nozzle.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tadataka Murakami 4026 Kuji-cho, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Hitachi Ltd. (72) Inventor Tomio Kuroda 3-1-1 Sachimachi, Hitachi City, Ibaraki Stock Hitachi, Ltd. Hitachi factory (72) Inventor Shigeru Shodohata 3-1-1, Saiwaicho, Hitachi, Ibaraki Stock company Hitachi Ltd. Hitachi factory

Claims (22)

[Claims] 1. A combustion apparatus equipped with a premixed combustion burner for injecting a mixed flow of fuel and air to form a complete combustion flame, the composition of the fuel flowing into the burner, the water concentration of the air, the temperature of the air and the air. A combustion apparatus comprising combustion control means for controlling at least the amount of fuel or air supplied to the burner such that the calculated flame temperature obtained from the ratio and the calculated flame temperature fall within a preset allowable range. 2. The combustion apparatus according to claim 1, further comprising a premixed combustion burner for ejecting fuel and air as a mixed flow of excess air. 3. The combustion apparatus according to claim 1, further comprising a premixed combustion burner for ejecting fuel and air as a mixed flow having an air ratio of 1.0 or more and 2.2 or less. 4. A combustion apparatus, wherein the flame temperature obtained by the calculation is an adiabatic flame temperature. 5. A combustion apparatus equipped with a premixed combustion burner for ejecting a mixed flow of fuel and air to form a complete combustion flame, the composition of fuel flowing into the burner, the water concentration of air, the temperature of air and the air. Combustion control means for controlling at least the amount of fuel and / or air supplied to the burner is provided so that the calculated flame temperature obtained based on the ratio falls within an allowable range set in advance corresponding to the load. Combustion device. 6. A combustion apparatus comprising a plurality of premixed combustion burners for ejecting a mixed flow of fuel and air to form a complete combustion flame, wherein the composition of the fuel flowing into each burner, the moisture concentration of the air, and the air. Combustion control means is provided for controlling the amount of fuel and / or air for each burner so that the calculated flame temperature obtained for each burner from the temperature and the air ratio falls within a preset allowable range. Combustion device characterized by the above. 7. A combustion apparatus equipped with a premixed combustion burner for ejecting a mixed flow of fuel and air to form a complete combustion flame, the composition of the fuel flowing into the burner, the water concentration of the air, the temperature of the air and the air. A combustion apparatus comprising a combustion control means for controlling at least the amount of fuel or air supplied to the burner so that the calculated flame temperature obtained from the ratio does not exceed a preset limit value. 8. A combustion apparatus according to claim 1, further comprising a diffusion combustion burner that forms a diffusion combustion flame of fuel and air, in addition to the premixed combustion burner. 9. A combustion control device for a combustor having a premixed combustion burner for forming a complete combustion flame, the flame being controlled from the composition of the fuel flowing into the burner, the moisture content of the air, the temperature of the air and the air ratio. Means for calculating temperature,
A combustion control device for a combustor, comprising: means for calculating at least the amount of fuel and / or air supplied to the burner so that the flame temperature falls within an allowable range set in advance corresponding to the load. . 10. A combustion control device for a combustor having a premixed combustion burner for forming a complete combustion flame, which is insulated from the composition of the fuel flowing into the burner, the moisture concentration of air, the temperature of air and the air ratio. Correlation between means for obtaining flame temperature by calculation and adiabatic flame temperature and NOx emission concentration, CO emission concentration, ejection speed of premixed gas ejected from the burner at the time of flame blowout or combustion oscillation or flame flashback Means for presetting the allowable range of the adiabatic flame temperature based on at least one of the above, and calculating the amount of fuel and / or air supplied to the burner so that the adiabatic flame temperature obtained by the calculation falls within the allowable range. Means for supplying fuel to the burner based on the calculation result, and / or
Alternatively, a combustion control device for a combustor, comprising a flow rate adjusting means for adjusting the amount of air. 11. A combustion apparatus equipped with a premixed combustion burner for forming a complete combustion flame, which is calculated and obtained based on the composition of the fuel flowing into the burner, the water moisture concentration, the air temperature and the air ratio. A combustion apparatus comprising means for displaying the flame temperature and a preset allowable range of the flame temperature. 12. A combustion apparatus according to claim 11, further comprising: display means for displaying the calculated value of the flame temperature and a preset allowable range of the flame temperature together with time. 13. A combustion apparatus according to claim 11, further comprising means for displaying a required value and a measured value of a combustor outlet temperature corresponding to a load. 14. A combustion apparatus according to claim 11, further comprising display means for displaying an estimated value of NOx concentration and an actual measured value of NOx concentration having a correlation with the flame temperature. 15. The flame temperature obtained by calculation based on the composition of the fuel flowing into the burner, the moisture concentration of the air, the temperature of the air, and the air ratio according to claim 1, and the allowable range of the preset flame temperature. A combustion device comprising means for displaying. 16. A combustion control method in premixed combustion in which a mixed flow of fuel and air is ejected from a burner to form a complete combustion flame, wherein NOx emission concentration, CO emission concentration, flame blowout or combustion oscillation occurs. Alternatively, the allowable range of the adiabatic flame temperature is set in advance based on the correlation between the adiabatic flame temperature and at least one selected from the ejection speeds of the premixed gas ejected from the burner during flame flashback, and the fuel flowing into the burner is set. The amount of fuel and / or air supplied to the burner is controlled so that the adiabatic flame temperature calculated by the composition, the moisture concentration of air, the temperature of air, and the air ratio falls within the allowable range. Combustion control method. 17. A combustion control method in premixed combustion in which fuel and air are excessively mixed with each other to form a flame ejected from a burner, and NO discharged from the flame when the adiabatic flame temperature is constant.
The relationship between the rate of change in x concentration and the calorific value of fuel or the average number of carbon atoms in one molecule of fuel, and when the flame blows off, when vibration occurs, or when CO is generated, the flame temperature and the mixed gas of fuel and air At least one of the relations of the ejection velocity or the flow rate of the mixed gas is made into a function in advance, and by referring to these functions, at least one of the low NOx emission concentration, the blowout of the flame, the vibration, and the generation of CO A combustion control method characterized in that the amount of fuel and / or the amount of air supplied to the burner so as not to occur is determined according to the load. 18. The combustion control method according to claim 16, wherein a fuel substantially free of nitrogen in the molecule is supplied to the burner. 19. A combustor provided with a premixed combustion burner for ejecting a mixed flow of fuel and air to form a flame, a compressor for air supplied to the burner, and a combustion gas discharged from the combustor. A gas turbine connected to the air compressor to be driven, a central operation room for sending a control command to a combustor in response to a load change of the gas turbine, and a generator connected to the gas turbine were provided. In the gas turbine power generator, the calculated value of the flame temperature obtained based on the composition of the fuel flowing into the burner, the moisture concentration of the air, the temperature of the air, and the air ratio is set in advance corresponding to the load of the gas turbine. A gas turbine power generator comprising combustion control means for controlling the amount of fuel and / or air supplied to the burner so as to fall within the range. 20. The load of the gas turbine and the amount of air supplied to the premixed combustion burner in the control section of the central operating room, and the flame formed by the load of the gas turbine and the premixed combustion burner according to claim 19. A gas turbine power generator comprising a program that relates the temperature of a gas or an adiabatic flame temperature. 21. The measurement result of fuel calorific value, air humidity, and air temperature, the amount of air supplied to the premixed combustion burner, the load of the gas turbine, and the flame formed by the premixed combustion burner according to claim 19. A means for determining at least one of a fuel supply amount, a fuel distribution ratio to each burner, and / or an air distribution ratio to each burner based on a program that relates the temperature of the burner or the adiabatic flame temperature. Characteristic gas turbine power generator. 22. The flue gas denitration device for reacting nitrogen oxide and reducing gas in the combustion exhaust gas discharged from the gas turbine according to claim 19, wherein the calorific value of the fuel at the same flame temperature, or Average carbon number and N in one molecule of fuel
A gas turbine power generator, wherein a control unit of the flue gas denitration device is provided with a program that associates a relationship with an Ox emission concentration.