JP3084643B2 - Burner combustion regulator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion control device for a commercial or industrial gas fuel burner, and more particularly to a burner control device capable of performing stable combustion even in a multi-burner such as a thermal power boiler. It is.

[0002]

2. Description of the Related Art In recent years, demand for coal-fired and gas-fired boilers has rapidly increased due to instability in the price of oil fuel. Since coal-fired boilers contain large amounts of ash and sulfur in the fuel, large-scale facilities are required for subsequent treatment, and it is difficult to construct such power generation facilities around large cities due to environmental problems. ing.

[0003] On the other hand, gas-fired boilers are expected to grow steadily in the suburbs of cities in the future because they contain such impurities in the fuel and have low pollution.

[0004] Although such a clean gas-fired boiler is used, pressure pulsation (hereinafter referred to as combustion oscillation) in the furnace tends to occur particularly during high load combustion. However, there is a disadvantage that structures and equipment directly attached to the boiler furnace such as a TV camera are easily damaged.

In general, the combustion oscillation phenomenon occurs when the heat release rate distribution inside the furnace is localized near the furnace wall (fuel burning speed is high and burns out near the burner outlet), or the flame is unstable and constantly fluctuates. (It repeats the phenomenon of sticking to the flame stabilizer and blowing away). Therefore, to suppress the combustion vibration in the related art, it is effective to improve the stability of the flame of the gas burner and to suppress the rapid combustion (for example, slow combustion, that is, to prolong the flame).

FIG. 5 shows a system diagram of a gas burner combustion device of a general gas-fired boiler. LNG, the main fuel, is sent from this receiving base to the thermal power plant by pipeline. Each of the burners 5 is gasified by a vaporizer (vaporizer) 51 in the power plant, and then the flow rate and the pressure are adjusted.
6 to form a flame 13. Normally, the gas pressure at the burner inlet is 1 atg to 3 atg at maximum load.
, But there is no particular pressure regulation value.

However, from the viewpoint of suppressing combustion oscillation, pressure pulsation in the furnace is hardly fed back to the fuel side.
It is better to increase the burner inlet pressure as much as possible. However, when the pressure exceeds 1 atg, the gas flow velocity reaches the sonic velocity at the nozzle outlet, and it is unlikely that the pressure pulsation of the furnace directly affects the pressure fluctuation of the fuel. Therefore, it is considered that there is not so much combustion vibration suppressing effect.

On the other hand, the combustion air is pressurized by an FDF (Force Ventilator) 52 and then supplied to a burner wind box 12 provided at each stage of the furnace. Normally, at the outlet of the FDF 52, the flue gas 54 and the FD
An air heater for exchanging heat with the combustion air from F52 is provided, but is omitted in FIG. Thereafter, the combustion air is sent to each burner and supplied into the furnace.

FIG. 6 is a sectional view showing the structure of a gas burner. The combustion air is divided into radial portions from the center of the burner and supplied into the furnace. In the figure, an example in which three flow paths are divided is shown. The secondary air 62 is swirled by an axial swirler (swirl vane) 66, and the tertiary air 63 is swirled by the air register 22. Due to the swirling effect of the combustion air, a large circulation region is formed behind the burner, which greatly contributes to the ignition stability of the gas fuel.

[0010]

[0005] In Japan, a new boiler for power generation will have a 500
Although it was MW / can, it was increased to 600 MW / can in 1989 and has been increasing year by year. For example, a power generation capacity of 600M
In a W boiler, 24 or more burners are installed, and it is difficult to adjust the combustion state of each burner in a short time.

Since combustion pulsation is an air column resonance phenomenon with a furnace, even a small pressure pulsation may accumulate energy and develop into large furnace pulsation. Even if only one of the 24 burners is the cause of the vibration, it can be a sufficient source of vibration to induce combustion vibration. However, in a power generation boiler or the like having a large number of burners, it is very difficult to find this one.

Further, when the instability of the flame is not the direct cause, for example, when the gap between the air flow velocity and the fuel injection velocity is large and the mixture rapidly mixes and there is a high heat generation area near the burner, the combustion oscillation is generated. Easy to trigger. Therefore, it is not an exaggeration to say that any combustion furnace has a possibility of causing combustion oscillation in gas combustion.

Normally, combustion vibration is likely to occur when a boiler is newly installed or during a test operation after a periodic inspection. In any case, the time given to combustion adjustment is small in order to start commercial operation early, and therefore, once the combustion vibration phenomenon occurs. When this occurred, a lot of work was required to find the cause in a short time and to take countermeasures.

[0014]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a pressure wave generator for supplying a pressure wave to a combustion furnace via a waveguide, and a pressure wave generator provided in a wind box. Input the information from the pressure measurement device, the flame brightness measurement device provided on the burner mounted on the wind box, and the pressure measurement device and the flame brightness measurement device, compare and calculate, and output the adjustment signal to each of the burners. The present invention provides a burner combustion adjustment device including a measurement control device.

According to the present invention, a pressure wave generated by a pressure wave generator is fed into a combustion furnace via a waveguide, and a pressure change in the wind box received by a pressure measuring device provided in the wind box is received. Information and the flame luminance change information received by the flame luminance measuring device provided in the burner mounted on the wind box are input to the measurement control device, and the combustion state information of all the burners is compared and calculated. To provide a burner combustion adjustment method that outputs an adjustment signal to the burner.

[0016]

[Function] Since combustion oscillation is a column resonance phenomenon of a furnace, it is important to understand the relationship (response) between the internal pressure of the furnace and heat generation. A pressure wave is forcibly applied to the furnace, and the acoustic response of each burner is measured by measuring the cross-correlation between the change in the brightness (heat generation) of the flame and the change in the pressure inside the wind box of the burner. Understand gender. Then, the burner is adjusted while measuring and evaluating the responsiveness (hereinafter referred to as τ) of each burner using the diagnostic apparatus according to the present invention. The main adjustment items for the burner are opening and closing operations of a combustion air swirl device, which is relatively easy to adjust.

There are various methods for changing τ.
For example, if the flame shape is changed, the temperature gradient near the burner changes, so that the acoustic resistance (acoustic impedance) changes, and as a result, τ also changes. However, it is extremely difficult to evaluate the flame itself as an acoustic characteristic, and it is still unknown what to adjust. Therefore, the driving device is installed in the combustion air swirler, not only in the new can but also in the existing can, and it is most efficient to change the resistance at this point.

[0018] The combustion oscillation is a gas column resonance phenomenon of a furnace,
Pressure pulsations inside the furnace affect the supply amount of burner fuel and combustion air, causing a temporal change in the heat generation rate, and are often generated by forming a feedback loop between them.

FIG. 3 shows the pressure pulsation in the furnace and the change over time of the heat generation rate among the mechanisms of the feedback type combustion oscillation. The combustion oscillation is generated when the pressure pulsation and the heat generation rate form a feedback loop. Generally, it is considered that vibration is likely to occur when the delay time τ in the figure is about 1/4 wavelength. As a measure for suppressing combustion pulsation, it is necessary to break a feedback loop based on the pressure pulsation and the heat generation rate. As a method thereof, it is effective to change τ in each burner by means such as increasing the pressure loss at the burner outlet.

However, as described above, since more than 24 burners are installed in the actual machine, it is very difficult to adjust τ of each burner, and τ has been evaluated up to now. There was no way.

According to the present invention, before the combustion oscillation occurs, a pressure wave is sent to the inside of the furnace, and the pressure received by each of the burners;
The response characteristic of each burner represented by τ is grasped from the fluctuation of the flame, and τ of each burner is adjusted so that τ of all burners does not match.

[0022]

【Example】

(I) Overall Configuration FIG. 1 shows a system diagram of a gas combustion diagnostic adjustment device according to the present invention.

The furnace 11 is provided with a burner-like box 12 through which combustion air is sent, and a flame 13 is formed. The pressure wave generator 16 may be attached to any part of the furnace. However, in the present embodiment, the pressure wave generator 16 is attached to the bottom of the furnace which is least affected by radiant heat from the furnace. It passes through the corrugated pipe 17 and is sent to the furnace. On the other hand, the information of the flame fluctuation is collected by the pressure measuring device 14 and the flame luminance measuring device 15 provided in each burner.

It is desirable that the time delay τ between the signal taken in by the pressure measuring device and the luminance signal of the flame is different for each burner, but actually, among a large number of burners, it happens that they are adjusted to be the same. It is thought that there is something. In that case, it is necessary to adjust again so that τ becomes random. The figure shows a system that drives the air register driver 23 based on the measured value of τ so that τ is changed by changing the resistance of the combustion air of the burner.

The measurement control computer 24 performs all the sequences of generation of the pressure wave, reception of the pressure wave, measurement of the change in the flame luminance, and change of the air register opening. , A signal is sent to the pressure wave generator driver 19. With regard to, after the pressure signal input to the pressure measuring device 14 is converted into an electric signal by the P / E converter 20, it is digitally converted and the data is taken in at high speed. With regard to (2), the luminance signal of the flame is converted into a voltage by using the O / E converter 21, and the digital conversion is performed in the same manner as described above, and the data is taken in at a high speed. With respect to (3), a digital opening signal is sent to the air register driver 23 to drive the register, change the acoustic resistance of each burner, and change the τ of each burner.
To adjust.

(II) Interrelationship and operation of each component FIG. 2 shows the minimum configuration of the gas combustion adjusting device. That is, a pressure wave generator 16, a pressure measuring device 14, and a flame luminance measuring device 15. Further, a pressure waveform 26, a pressure measurement device reception waveform 27, and a flame luminance measurement waveform 28 are shown in FIG. These waveforms are arranged in chronological order. First, the pressure wave generator 16
Generates a pulsed pressure signal and sends it into the furnace. In the figure, reference numeral 18 shows an image of a pressure wave in the furnace.

This pressure is received by the pressure wave measuring device 14 incorporated in each burner. Time delay τ for pressure oscillation and reception
₀ occurs. This value is different for each burner.
This is because the distance between the oscillating unit and the receiving unit differs depending on the burner, and when the two are connected at the shortest distance, the average temperature on the line also differs depending on the burner. Now, when the pressure inside the wind box of the burner increases, the pressure difference between the wind box and the furnace increases, so that the air flow rate passing through the burner increases. As a result, the combustion state changes, the combustion rate changes,
Brightness also increases.

Time delay τ ₁ between pressure change and luminance change
Is a unique value of each burner which is not related to the burner position unlike τ _0, and τ ₁ of the total number of burners is measured by using this method.

As an example of a method of adjusting τ ₁ , FIG. 1 shows an example in which the air register opening of the burner is changed.
The secondary vane opening degree may be used, and any means may be used. However,
Since the measurement of τ ₁ can be performed relatively quickly using a computer, it is desirable that τ ₁ be capable of automatically changing the combustion state taking advantage of this feature.

FIGS. 9, 10 and 11 show actual examples of the combustion oscillation mode in the actual boiler furnace. FIG. 9 shows a side section of the furnace and a vibration mode 101. In the figure, reference numeral 13 denotes a flame, which is a case where all the burners are ignited. In this case, since the furnace load is naturally high, there is a high probability that an accident will occur if combustion oscillation occurs. Normal,
In the combustion furnace employing the opposed combustion system, when all the burners are ignited and the load is high, the mode becomes the furnace depth direction without exception when combustion oscillation occurs. FIG. 10 and FIG. 11 show the relationship between the combustion oscillation mode and the ignition burner position which are often seen at the partial load when the fire extinguishing burner is present. The figure shows the relationship between the burner pattern and the vibration mode when the burner in the middle stage is extinguished in a combination of burners and furnaces arranged in three stages. The vibration mode has a property that the ignition burner position tends to be at the antinode 108 of the amplitude and the fire extinguishing burner position has the property of being at the node 107 of the amplitude. Tends to be in the vibration mode in the height direction.

FIG. 11 shows a case where a fire extinguishing burner exists, as in FIG. 10, but shows a case where the central burner of the furnace is extinguished and both burners are ignited. In the figure, the point fire extinguishing is illustrated by focusing only on the lowermost burner. However, when only the burners at both ends are ignited, the fire becomes an antinode of the amplitude, and it becomes easy to vibrate in the width direction of the furnace.

As described above, in a combustion furnace composed of a plurality of burners, there is a possibility of causing vibration in various modes depending on the burner pattern. Although it is desirable to suppress combustion vibration in all modes, it is most important in practice to suppress combustion vibration in the depth direction of the furnace shown in FIG. The reason is that all the burners are ignited and the furnace load is the highest among the three vibration modes shown in the figure, and if the combustion vibration is developed, a large accident is likely to occur. In other cases, even if it happens, the load is low and it is unlikely to lead to a major accident.

The vibration modes described above are for the case of opposed combustion and single-sided combustion, and in the case of a combustion furnace employing another combustion method, it is expected that the relationship between the load and the vibration mode will be different. For example, like corner firing,
This is because when the burners are arranged at the four corners, the vibration in the longitudinal mode seems to be dominant regardless of the furnace load as shown in FIG.

FIG. 4 shows the time change of the pressure fluctuation and the heat generation rate fluctuation in the vicinity of the burner in an example of i burners. If the delay time τ between the pressure fluctuation of each burner and the fluctuation of the heat generation rate is adjusted by the above-described method, the furnace as a whole is time-smoothed as shown in FIG. can do.

FIG. 7 shows an example of adjusting the inherent delay time τ ₁ of the burner during the opposed combustion. As shown in FIGS. 9, 10, and 11, although there are priorities, it is desirable to suppress vibration modes in the depth (X), width (Y), and height (Z) directions. Therefore, this is an example in which τ is adjusted so that it does not easily match in the X, Y, and Z directions.

In the example of FIG. 7, when comparing τ before and after the can, the cumulative τ before the can and the cumulative τ after the can are substantially equal.
As a method of actually adjusting τ, when a method using an air register is adopted, it is understood that it is preferable to adjust the flow rate of combustion air to the furnace so that it is balanced before and after the can.

FIG. 8 shows an example in which the pressure wave generator is attached to the after-air port 55. Pressure wave generator 16
This is an example in which the apparatus can be attached to any part of the furnace, but is attached to an after-airport portion which is considered to have a relatively small amount of fuel and air control devices and secure an installation space.

The pressure wave generated by the pressure wave generator 16 passes through the waveguide 17 and is sent to the furnace. On the other hand, the information of the flame fluctuation is taken in by the pressure measuring device 14 and the flame luminance measuring device 15 provided in each burner.

[0039]

According to the present invention, since the acoustic response characteristics of each burner can be grasped, the burner state can be quickly known at the time of test operation or at the time of performing the multi-burner adjustment after the periodic inspection. Combustion oscillation can be suppressed.

Accordingly, even if there is some difficulty in the production accuracy of each gas burner, it is possible to prevent the development of combustion oscillation due to this, so that it is possible to save labor and time for the combustion adjustment at the time of test operation, and to greatly shorten the time. As a result, safe operation of the combustion furnace can be achieved.

[Brief description of the drawings]

FIG. 1 is a system diagram of a burner combustion adjusting device according to the present invention.

FIG. 2 is a diagram showing the relationship between a pressure wave generator, a pressure measuring device, and a flame luminance measuring device in a burner combustion adjusting device according to the present invention, and the time delay of each signal.

FIG. 3 is a diagram showing a relationship between pressure pulsation in a combustion furnace and heat generation rate fluctuation.

FIG. 4 is a diagram showing the relationship between pressure pulsation inside the combustion furnace and heat generation rate fluctuation in the vicinity of each burner.

FIG. 5 is a system diagram of a general gas combustion furnace.

FIG. 6 is a sectional view of the gas burner of FIG.

FIG. 7 is a diagram showing an example of adjusting a time delay τ between the pressure of each burner and the flame brightness in the opposed combustion furnace according to the present invention.

FIG. 8 is a system diagram of another embodiment according to the present invention.

FIG. 9 is a diagram showing a burner arrangement of a combustion furnace and a depth direction vibration mode of the furnace.

FIG. 10 is a diagram showing a burner arrangement of a combustion furnace and a vibration mode in a height direction of the furnace.

FIG. 11 is a diagram showing a burner arrangement of a combustion furnace and a vibration mode in a width direction of the furnace.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Combustion furnace 12 Wind box 13 Flame 14 Pressure measuring machine 15 Flame luminance measuring machine 16 Pressure wave generator 17 Waveguide 18 Pressure wave 19 Pressure wave generator driver 20 P / E converter 21 O / E converter 22 Air register Reference Signs List 23 Air register driver 24 Measurement control device (CPU) 26 Pressure waveform 27 Pressure measurement device reception waveform 28 Flame luminance measurement device reception waveform 31 Delay time 51 Vaporizer 52 Push-in ventilator 53 Exhaust gas circulation fan 54 Combustion exhaust gas 55 After air port 56 Burner 61 1 Secondary air 62 Secondary air 63 Tertiary air 64 Gas fuel 65 Gas element 66 Secondary vane 67 Flame stabilizer 68 Gas fuel manifold 71 Burner panel before can 72 Burner panel after can 101 Combustion furnace depth direction vibration mode 102 Combustion furnace height Directional vibration mode 103 combustion Furnace width direction vibration mode 104 Hopper 105 Operating burner 106 Stop burner 107 Node of amplitude 108 Antinode of amplitude

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinichiro Nomura 3-36 Takara-cho, Kure City, Hiroshima Prefecture Inside the Kure Research Laboratory, Babcock Hitachi Ltd. (56) References JP-A-60-69428 (JP, A) JP-A Heihei 2-1033312 (JP, A) Japanese Utility Model Showa 61-101244 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F23N 5/08

Claims (6)

(57) [Claims] 1. A pressure wave generator for feeding a pressure wave into a combustion furnace via a waveguide, a pressure measuring device provided in a wind box, and a burner provided in the wind box. A burner, comprising: a flame luminance measuring device; and a measurement control device that receives information from the pressure measuring device and the flame luminance measuring device, performs a comparison operation, and outputs an adjustment signal to each of the burners. Combustion control device. 2. The burner combustion regulating device according to claim 1, wherein said pressure measuring device is mounted inside said wind box. 3. The burner combustion regulating device according to claim 1, wherein said pressure measuring device is mounted outside said wind box. 4. The burner combustion regulating device according to claim 1, wherein said pressure wave generator is attached to a furnace bottom via a waveguide. 5. The pressure wave generator is mounted on an after-air port at the upper part of the furnace via a waveguide.
Burner combustion regulator. 6. A pressure wave generated by a pressure wave generator is fed into a combustion furnace through a waveguide, and information on a pressure change inside the wind box received by a pressure measuring device provided in the wind box is provided. The flame luminance change information received by the flame luminance measurement device provided in the burner provided in the wind box is input to a measurement control device, and the combustion state information of all the burners is compared and calculated, and the individual burners are calculated. Burner combustion adjustment method that outputs an adjustment signal to the burner.