JP2634240B2 - Burner burning method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for burning a burner such as a boiler.

[Conventional technology]

A conventional boiler will be described with reference to FIGS. 7 is an overall configuration diagram (omission of a fuel supply line and an air line), FIG. 8 is an overall configuration diagram including a fuel supply line, and FIG. 9 is an overall configuration diagram including an air line.

In the conventional boiler, as shown in FIGS. 7 to 9, the fuel sprayed from a plurality of burners 02 provided in the boiler 01 is burned by air mixed simultaneously. In the conventional low NOx, the fuel is not completely combusted in the primary fuel zone 03, but is moved to the secondary combustion zone 04 while leaving a part of the unburned portion. Burns completely. Thereafter, the air is discharged from the chimney 07 through the flue 06. 8 and 9, 08 is a fuel valve, 09 is air in a burner unit, a recirculation gas pipe, 15 is a recirculation gas flow control damper, 11 is an air flow control damper, and 12 is an individual burner recirculation gas adjustment. A damper, 13 denotes an individual burner primary air flow rate adjustment damper, and 14 denotes an individual burner secondary air flow rate adjustment damper.

Generally, NOx of exhaust gas is regulated at the outlet of the chimney 07, so that the final NOx in the exhaust gas is measured at the base of the chimney. Since the NOx concentration in the exhaust gas is finally determined through such a combustion process, the NOx generation state of a single burner does not necessarily lead to the final NOx. However, since air is supplied in the secondary combustion zone 04 to a set of combustion gases of several burners, each burner burns stably and uniformly,
Being at a certain NOx level means that in the secondary combustion zone 04
Although it is indispensable to secure the final NOx level by adjusting the amount of FA or air for two-stage combustion 05, there has been no technology to evaluate the NOx level of each burner based on the combustion results. Therefore, we had to look at the final output and adjust many parameters by estimation, which was a kind of masterpiece.

[Problems to be solved by the invention]

The conventional method has the following problems and problems.

(A) The optimum combustion conditions set during the initial adjustment operation of the plant change depending on the operation progress of the plant. However, there is no method for accurately grasping the combustion state of each burner.

(B) If the change in the combustion state of each burner is properly grasped and adjusted, it becomes easy to maintain the entire combustion system in a good state, that is, a state of low NOx.

[Means for solving the problem]

 The present invention takes the following means in order to solve the above problems.

(1) In a combustion device having a plurality of burners, the surface temperature distribution of the individual burner flame during combustion is sequentially divided into predetermined temperature ranges, and when the burner is in a predetermined combustion state in advance, the area of the predetermined division is determined. Calculated the ratio to the area of all sections, and operated the air flow rate, fuel flow rate, and recirculation gas amount to maintain the same ratio during operation.

(2) As a method of monitoring burner-generated NOx, in a combustion device having a plurality of burners, the surface temperature distribution of the individual burner flame during combustion is sequentially divided into predetermined temperature ranges, the area of each section is determined, and the predetermined classification is performed. The ratio of the area of the area to the area of all the sections is calculated, and the ratio obtained in advance and the ratio of the combustion device
The NOx generation amount was monitored from the correlation with the NOx generation amount.

[Action]

(1) By the above means, the surface temperature distribution of the individual burner flame during combustion is measured by, for example, a thermal camera or the like, and the individual burner flames are sequentially sorted from a high temperature side to a low temperature side for each predetermined temperature range.
Next, for example, the ratio of the area of the highest temperature section and the area obtained by adding the highest temperature section and the next temperature section to the area of all sections is obtained. The air flow rate, the combustion flow rate, and the recirculation gas amount are adjusted so as to maintain the above-mentioned ratio in the predetermined combustion state obtained in advance. Since there is a strong correlation between the combustion state and the ratio, the combustion state of the individual burner can be maintained in a good state in this way.

(2) By the above means, the surface temperature distribution of the individual burner flame during combustion is measured by, for example, a thermal camera or the like, and the individual flames are sequentially classified from a high temperature side to a low temperature side for each predetermined temperature range.
Next, for example, the ratio of the area of the highest temperature section and the area obtained by adding the highest temperature section and the next temperature section to the area of all sections is obtained. The NOx generation amount is obtained from the correlation between the above-mentioned ratio and the NOx generation amount of the combustion device, which is obtained in advance, and the actual ratio, and the NOx generation amount is monitored.

In this way, the individual burner generation NOx is easily monitored.

〔Example〕

(1) One embodiment to which the method of the present invention described in claim (1) is applied will be described with reference to FIGS. 1 to 4, FIG. 8, and FIG.

In the description of the related art, a description for avoiding redundancy is omitted, and a description will be given mainly of a portion related to the present invention.

First, as shown in FIG. 1, the distribution of the surface temperature of the flame during combustion of the burner 02 is measured by an optical method. In this case, the definition of the surface temperature of the flame is complicated because the permeability changes depending on the type of the flame, but it is measured in this embodiment, which tries to estimate the NOx generation situation by comparing the combustion with the same fuel and the same burner. The method and the definition of the temperature to be measured do not require much rigor.

As the measuring method, any of known methods such as an optical method (thermal camera method, spectral method) and a thermocouple method can be adopted. For example, on a screen obtained by a thermal camera, the screen can be divided into appropriate dimensions and the area can be determined for each temperature range. The temperature at each point on the side of the flame obtained by the measurement is divided into appropriate temperature steps, for example, every 100 ° C. as shown in FIG. 1, and an isotherm distribution chart from 1,500 ° C. to 1,200 ° C. is created. The temperature of the flame gradually decreases outward from the hottest part 15 at the center, but in order to determine up to which point the flame is, the point at which the temperature difference with the surrounding gas temperature disappears is determined by the flame. Defined as whole (total area) 12.

Next, the area of each temperature section is determined, and is set as S ₁ , S ₂ , S ₃ , and S ₄ .
At this time, the relationship between the area of each section and the temperature range is as shown in Table 1.

Therefore, the area S _{0 of} all sections is given by the equation (1).

S ₀ = S ₁ + S ₂ + S ₃ + S ₄ (1) Next, the ratio R ₁ of the area S ₁ of the highest temperature section N _{1 to} the area of all sections is obtained from the equation (2).

R ₁ = S ₁ / S ₀ (2) Similarly, the ratio R ₂ of S ₁ and S ₂ occupying S ₀ is determined by equation (3).

R ₂ = (S ₁ + S ₂ ) / S ₀ (3) For the above ratios R ₁ and R ₂ , values in the combustion state of each burner in the normal combustion state of the boiler are experimentally obtained in advance. During the actual operation, the air flow is distributed so that R ₁ and R ₂ become the respective values (the air flow control damper shown in FIG. 9).
11, opening and closing of the primary air flow rate adjusting damper 13 and the secondary air flow rate adjusting damper 14, and adjusting the combustion flow rate (the fuel injection valve 08 in FIG. 8).
Opening and closing), adjusting the amount of recirculated gas (opening and closing the recirculated gas flow control damper 10 and the burner recirculated gas adjusting damper 12 in FIG. 9), and the like. In this way, the combustion state of each burner can be easily and satisfactorily maintained.

Next shown as an index of the ratio R _2, the results of evaluation tests of the combustion state of the burner at an actual plant in Figure 2. FIG. 3 shows an arrangement diagram of the burners at the time of the test. As can be seen from FIG. 2, the optimum combustion state is the low NOx and low dust state obtained under condition 4. In the test, a wide range of combustion conditions was simulated by changing the amount of O _2, which is a representative element that changes the combustion conditions. That is, the air flow control damper 11
(FIG. 9) was opened and closed to increase or decrease the total air volume. Under the optimum combustion condition 4, R ₂ shows a high value for all three burners, indicating that the combustion state is good with uniformity being maintained.
R ₂ values of the conditions 1 to 3 in three burner large low fluctuation. This indicates that the combustion state of the burner has deteriorated and that the uniformity has been lost. As a result NOx
Or the amount of soot and dust increased.

From the above experimental results index R ₁ of the present embodiment and / or
Combustion state at R ₂ indicating that can prove that it is possible to evaluate accurately.

Although the measurement of the surface temperature distribution has been described only conceptually in the above description, an apparatus for obtaining the surface temperature distribution of a burner flame will be described in detail below.

In FIG. 4, one or a plurality of image fibers 3 for observing the flame 2 of the burner 02 are installed in the furnace 1, and a color television camera 4 is connected to the image fiber 3. The output of the camera 4 is input to a dynamic color video display 20 and connected to a decoder 5. The output of the camera 4 is input to a frame memory 7 via a red (R), green (G), and blue (B) video device 6. Is done. The output of the frame memory 7 is a primary arithmetic circuit (R / R) for calculating the temperature from the R signal and the B signal.
B), 8, a primary operation circuit (G
(T ₁ ) −G (t ₂ )) 9 and a primary arithmetic circuit (RB) 10 for calculating smoke. The output of the primary arithmetic circuit (R / B) 8 is sequentially displayed on a temperature distribution display 16,
The secondary operation circuit 17 is connected to the evaluation circuit 18. Similarly, the primary arithmetic circuit _{(G (t 1) -G (} t 2)) 9, and the output of the arithmetic circuit (R-B) 10 is connected directly to the evaluation circuit 18. Further, the output of the evaluation circuit 18 is connected to a display 19.

In the above-described apparatus, an image captured by the color television camera 4 via the image fiber 3 is sent directly to the dynamic color image display 20 to provide a monitor image to an operator or the like, and is also sent to the decoder 5.
In general, the output signal of the color television camera 4 is composed of red, green, and blue separated images and sent by one line to save transmission lines, and is separated into the original three-color image 6. The images of these three colors (red, green, and blue) are images proportional to the respective component intensities of the spectrum radiated by the flame 2. The video separated into these three colors is temporarily recorded in the frame memory 7 in the form of video for later calculation. Based on this video record, the temperature distribution representing the flame is calculated based on the following principle.

Radiation from a black body at a certain temperature T ゜ k is expressed by the following equation (4) according to Planck's law of radiation.

E (λ · T) = C ₁ / λ ⁵ exp (C ₂ / λT−1) (4) where λ: wavelength (μm) T: absolute temperature (K) C ₁ : first radiation constant of Planck 3.7415 (W ・ μm ⁴・ c
m ⁻² ) C ₂ : Planck's second radiation constant 1.4388 × 10 ₄ (μm · k) The radiation energy distribution of a substance other than a black body, that is, the flame, is obtained by multiplying equation (4) by the emissivity ε _λ Become.

The radiation curves in FIG. 5 show the radiant energy of a fire at a certain fire temperature A (K). If the fire temperature changes, a radiation curve group having the same tendency can be obtained using the temperature T as a parameter. . Note that this curve is changed analogously the emissivity epsilon _lambda is changed. However, it is well known that the radiation energy ratio of two wavelengths is a function of temperature only if the ratio of emissivity ε at the two wavelengths is constant, even if the radiation law changes, and it is well known that it is commercialized as a two-color thermometer. Have been. R (red), G as shown by the dotted line superimposed on the radiation curve of FIG.
The temperature is calculated in the same manner as a two-color thermometer using R / B from, for example, R and B signals of a color television camera having relative sensitivity curves of (green) and B (blue). In this case, the color signal is the component around the center wavelength of the relative sensitivity curve of the color.
This is integrated along the radiation curve.

 Thus, the temperature distribution of the flame is calculated.

(2) One embodiment to which the method of the present invention described in claim (2) is applied will be described with reference to FIGS. 6 and 7. FIG.

The description of the portions described in the conventional example and the embodiment is omitted to avoid redundancy, and portions related to the present invention will be mainly described.

As described above, according to the above equations (1) to (3),
The ratios R ₁ and R ₂ which are indicators of the combustion state of each burner are obtained, and the NOx generation amount is monitored from the correlation between the boiler NOx generation amount and R ₁ and R ₂ which have been obtained experimentally in advance. .

An experimental example will be described to specifically show the above. When one burner is burned in a test furnace and the correlation between the total amount of NOx at the furnace outlet and the ratios R ₁ and R ₂ is obtained, the relationship shown in FIG. 6 is obtained. Accordingly, if the correlation between the ratios R ₁ and R _{2 of} each burner 02 (FIG. 7) and the NOx generation amount of the boiler 01 is determined in advance and the ratios R ₁ and R ₂ are measured and determined, the combustion conditions It is possible to monitor a change in the NOx generation amount due to the change.

〔The invention's effect〕

As described above, according to the present invention: (1) Since the change over time in the combustion state of the individual burner can be accurately grasped, it is possible to easily readjust the combustion state to a more ideal combustion state, and as a whole the boiler, It is possible to maintain a well-balanced combustion state.

(2) Since the change over time in the combustion state of the individual burner can be grasped as a NOx-related quantity, it can be easily re-adjusted to a more ideal combustion state, and the boiler as a whole has a well-balanced NOx combustion state. Will be able to keep it.

[Brief description of the drawings]

FIG. 1 is a flame temperature distribution diagram as an explanatory diagram of an embodiment according to claim (1) of the present invention, FIG. 2 is an operational explanatory diagram of the embodiment, and FIG. FIG. 4 is a block diagram of the temperature distribution measuring device of the embodiment, FIG. 5 is an operation explanatory diagram of the temperature distribution measuring device of the embodiment, and FIG. FIG. 7 is an explanatory view of the operation of one embodiment relating to (2), FIG. 7 is an overall configuration diagram of a conventional boiler (fuel supply line and air line are omitted), and FIG. 8 is an overall configuration diagram of the conventional example (fuel supply line) FIG. 9 is an overall configuration diagram (including an air line) of the conventional example. 01 ... Boiler body, 02 ... Burner, 03 ... Primary combustion zone, 04 ... Secondary combustion zone, 05 ... Air blown secondary, 06 ... Arrow indicating flue, 07 ... Chimney, 08: Fuel valve, 09: Air per burner, recirculation gas piping, 1,2: Flame total area, 11: Air flow control damper, 12: Individual burner recirculation gas adjustment damper, 13… Individual burner primary air flow adjustment damper, 14… Individual burner secondary air flow adjustment damper, 15… Recirculation gas flow control damper.

Continued on the front page (72) Inventor Nobuya Watanabe 1-1, Akunoura-cho, Nagasaki-shi, Nagasaki Mitsubishi Heavy Industries, Ltd. Nagasaki Research Laboratory (72) Inventor Yasuhiko Sato 1-1-1, Akunoura-cho, Nagasaki-shi, Nagasaki Mitsubishi Heavy Industries Inside the Nagasaki Research Laboratory Co., Ltd. (72) Matsudaira Noda 1-1, Akunouramachi, Nagasaki City, Nagasaki Prefecture Mitsubishi Heavy Industries, Ltd. Inside the Nagasaki Research Laboratory Co., Ltd. (72) Kimiyo Tokuda 1-1-1, Akunouramachi, Nagasaki City, Nagasaki Prefecture Mitsubishi Heavy Industries (72) Inventor Yuichi Ide 1-1, Akunouramachi, Nagasaki City, Nagasaki Prefecture Mitsubishi Heavy Industries Incorporated Nagasaki Laboratory (72) Inventor, Masami Iida 1-1-1, Akunouramachi, Nagasaki City, Nagasaki Prefecture Mitsubishi Heavy Industries (72) Inventor Shoji Tsujidake 1-1, Akunouramachi, Nagasaki City, Nagasaki Prefecture Mitsubishi Heavy Industries, Ltd. Nagasaki Shipyard (56) References JP-A-56-23630 (JP, A) JP-A-58-19608 (JP, A) JP-A-60-238613 (JP, A)

Claims (2)

(57) [Claims] In a combustion apparatus having a plurality of burners, a surface temperature distribution of an individual burner flame during combustion is sequentially divided for each predetermined temperature range, and when the burner is in a predetermined combustion state in advance, a predetermined division is performed. A burner combustion method characterized in that a ratio of the area of the burner to the area of all sections is determined, and an air flow rate, a fuel flow rate, and a recirculation gas amount are controlled so as to maintain the same ratio during operation. 2. In a combustion apparatus having a plurality of burners, the surface temperature distribution of an individual burner flame during combustion is sequentially divided for each predetermined temperature range, and the area of each section is obtained. N the Uranairu proportion to the area of the calculated, from correlation between advance the proportions had been determined and NO _x generation amount of the combustion device
A burner combustion method that monitors the amount of O _x generated.