JP3150474B2 - Control method of gas fuel low oxygen burner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas-fired burner using a gas having a lower oxygen concentration than the atmosphere (for example, an exhaust gas of a gas turbine or a diesel engine) as combustion air, and a control method thereof. Applicable to boilers for power generation business, other industrial boilers, chemical industrial furnaces, etc.

[0002]

2. Description of the Related Art FIG. 3 is a vertical sectional side view showing an example of a conventional gas fuel fired low oxygen burner, FIG. 4 is a front view taken along the line IV-IV of FIG. 3, and FIG. FIG.

[0003] In these figures, (01) is a boiler body, (02) is a burner-like box, (03) is a primary air cylinder,
(04) is a secondary air cylinder, (05) is a tertiary air cylinder, (0)
6) is a guide pipe, (07) is a flame stabilizer, (08) is a flame detector, (09) is a damper for adjusting primary air flow, (1)
0) is a damper for adjusting secondary air flow, (11) is a damper for adjusting tertiary air flow, (12) is a burner throat refractory material,
(13) inside the furnace, (14) rich fuel gas nozzle, (1)
5) is a rich fuel gas header, (16) is a rich fuel gas pipe,
(17) is a lean fuel gas nozzle, (18) is a lean fuel gas header, (19) is a lean fuel gas pipe, (20) is a rich fuel gas, (21) is a lean fuel gas, (22) is combustion air,
(23) is primary air, (24) is secondary air, (25) is lean fuel premixed air, (26) is tertiary air, (27) is a primary air passage, (28) is a lean fuel premixed chamber, (29) indicates a rich fuel flame, and (30) indicates a light fuel flame.

In such a burner, the combustion air (22) sent from a blower (not shown) into the burner wind box (02) includes primary air (23), secondary air (24) and It is diverted to tertiary air (26). The split flow of the combustion air (22) is supplied to the air flow rate adjusting dampers (09), provided at the inlets of the primary, secondary, and tertiary air cylinders (03), (04), and (05). (10), (1
This is performed according to 1).

[0005] The primary air (23) enters the primary air cylinder (03), and a flame stabilizer () is attached to the tip of a guide pipe (06) provided at the center of the same air cylinder (03). 07) (partially through the flame stabilizer (06)) and into the furnace (13). Secondary air (24)
Is mixed with a separately fed lean fuel gas fuel (21) in a lean fuel premixing chamber (28) having an annular cross section formed by a primary air cylinder (03) and a secondary air cylinder (04), Light fuel mixture (25) is formed and inside the furnace (11)
Blown into The tertiary air (26) is the primary air (23)
Although it is smaller than that of the secondary air (24), it is blown into the furnace (13) from an annular cross-section passage formed by the secondary air cylinder (04) and the tertiary air cylinder (05), and used for combustion. Is done.

On the other hand, the rich fuel gas (20) and the lean fuel gas (21) pumped from a gas fuel supply device (not shown) through the rich fuel gas pipe (16) and the lean fuel gas pipe (19). Correspond to the rich fuel gas header (15) and the lean fuel premix chamber (28) in the primary air passage (27), respectively.
To the lean fuel gas header (18).

The rich fuel gas (20) sent into the rich fuel gas header (15) is provided on the outer peripheral portion of the flame stabilizer (07) at the tip of the guide pipe (06) in the primary air cylinder (03). The plurality of rich fuel gas nozzles (14) are injected into the furnace (13) and ignited by an ignition source (not shown) to form a rich fuel flame (29). Flame stabilizer (07)
The rich fuel gas (2) injected into the furnace (13) from the outer periphery
Part of the flame stabilizer (0) is partly separated by the primary air (23) flow.
It is engulfed in the vortex formed on the back side of 7) and ignites, forming an ignition source. Therefore, the rich fuel flame (29) is ignited from the vicinity of the flame stabilizer (07), and a diffusion flame having extremely high ignition stability is formed.

On the other hand, the lean fuel gas (21) sent into the lean fuel gas header (18) is blown into the lean fuel premixing chamber (28) from the lean fuel gas nozzle (17), and is separately sent. Mixed with the secondary air (24) to form a lean fuel premix (25). Then, it is blown into the furnace (11) and ignited by an ignition source (not shown) to form a light fuel flame (30).

Usually, rich fuel flame (29) and light fuel flame
(30) air ratio λ_CAnd λ_W[Λ _C= Primary air volume /
(Rich fuel gas amount x theoretical combustion air amount), λ_W= Secondary air volume
/ (Lean fuel gas amount x theoretical combustion air amount)] is nitrogen oxide
(Hereinafter NO_x) To suppress the occurrence of
_CLess than about 1.0, λ_WIs set to about 2. Fig. 6 shows gas
NO of fuel_xShows the relationship between the generation amount and the air ratio.
Λ_CAnd λ_WAn example of the set value of is shown. In FIG.
The rich fuel flame (29) is λ_C= 0.35, light fuel
Flame (30) is λ_W= 2.10, the air ratio of the entire burner
λ_TIs set to 1.05.

Since the rich fuel flame (29) is a diffusion flame and has a low air ratio λ _C , the primary air (23) contains the rich fuel flame (2).
It is consumed for combustion near the ignition part of 9). On the other hand, the lean fuel flame (30) is a premixed flame, and completes combustion almost instantly when ignited. The remaining secondary air (24) is diffused and mixed with the rich fuel flame (29), and the tertiary air (26) is further diffused and mixed to complete the combustion.

A flame detector (08) is mounted in the guide pipe (06) to detect the presence or absence of a flame in the furnace (13).

[0012]

The stability of the flame as a whole burner depends on how stable the ignition of the rich fuel flame (29) takes place. Rich fuel flame (29)
From the results of experiments conducted by the inventors of the present invention so far, it has been found that the flow velocity of the primary air (23) at the outlet of the primary air cylinder (03) has the greatest influence on the ignition stability of the fuel cell. did. FIG. 7 shows the ignition limit of the gas-fuel-fired burner based on the experimental results of the inventors and the like, as a relationship between the oxygen concentration in the primary air (23) and the flow rate of the primary air (23). FIG. 8 shows that the primary air (2
The primary air (2)
3) The relationship between the flow velocity and the flame stabilizer (07) metal temperature is shown. FIG. 8 shows that the ignition stability of the gas-fuel-fired burner must be maintained by decreasing the flow rate of the primary air (23) as the oxygen concentration of the primary air (23) decreases.

However, a gas turbine or a diesel engine that has supplied exhaust gas as combustion air suddenly trips, and the air (O ₂ = 2) is used as the alternative combustion air (22).
(1%) is blown, the ignition stability of the flame of the gas fuel fired burner is enhanced, but at the same time, the metal temperature of the flame stabilizer (07) rises sharply, and the flame stabilizer (07) may be burned out ( See FIG. 8). In such a case, in the conventional burner, the flow rates of the secondary air (24) and the tertiary air (26) are reduced in order to increase the flow rate of the primary air (23), but the flow rate of the secondary air (24) is reduced. If it is too long, the fuel concentration of the fresh fuel premixture (25) increases, and the flow velocity decreases. Therefore, although these flow rates are adjusted very carefully, the primary, secondary and tertiary air flow rate adjusting dampers (09), (10), (1)
1) Since all operations have to be performed, it is very time-consuming.

[0014] The present invention provides a method for igniting a flame even when the oxygen concentration of the combustion air suddenly changes during combustion due to a trip of a gas turbine or a diesel engine, which is a supply source of the combustion air, or the start of the operation thereof. An object of the present invention is to make it possible to easily ensure stability and prevent metal temperature rise of a flame stabilizer.

[0015]

The present invention SUMMARY OF], in order to achieve the above object, proposes a control method for a gas fuel hypoxia burners below.

1) A primary air cylinder arranged at the axis, a secondary air cylinder arranged coaxially around the same air cylinder, and a tertiary air cylinder arranged coaxially around the same secondary air cylinder A rich fuel gas nozzle installed in the primary air cylinder, a light fuel gas nozzle installed in an annular cross-section passage formed by the primary air cylinder and the secondary air cylinder, and a fuel gas nozzle installed in the primary air cylinder.
Primary and secondary air communication ports that communicate between the inside and outside,
An opening adjustment damper provided at the same primary / secondary air communication port, and the gas fuel injected from the rich fuel gas nozzle and the lean fuel gas nozzle is burned by a gas having an oxygen concentration lower than the atmosphere. by, the diffusion flame to the gas fuel injected from the dark fuel gas nozzle, premixed flame gas fuel injected from the light fuel gas nozzle, the gas fuel hypoxic burner so as to form respectively, a flame detection
Output of the vessel, metal temperature of the flame stabilizer and the acid contained in the above gas
A method for controlling a gas-fueled low-oxygen burner , comprising controlling the opening degree adjustment damper based on an element concentration .

2) The method for controlling a gas-fueled low-oxygen burner according to 1) above, wherein the output of the flame detector is a predetermined value.
In the following cases, the opening adjustment
The metal temperature of the above flame holder increases as
When the value is equal to or greater than the predetermined value, the opening degree is independent of the oxygen concentration.
A method for controlling a gas-fueled low-oxygen burner, comprising closing an adjustment damper .

[0018]

[0019]

In the present invention, the primary air cylinder of the gas fueled low-oxygen burner is provided with primary and secondary air communication ports communicating between the inside and the outside, and the opening adjustment damper is provided at the same primary and secondary air communication ports. Therefore, by controlling the opening adjustment damper based on, for example, the output of the flame detector, the metal temperature of the flame stabilizer, and the oxygen concentration of the combustion gas (low oxygen air), the furnace from the outlet of the primary air cylinder By adjusting the flow rate of the primary air blown into the inside, the ignition stability can be maintained while preventing the metal temperature of the flame stabilizer from excessively increasing.

In particular, when the output of the flame detector is equal to or less than a predetermined value, the opening adjustment damper is opened regardless of the oxygen concentration, and when the metal temperature of the flame stabilizer is equal to or higher than a predetermined value, the opening is adjusted. By closing the opening adjustment damper irrespective of the oxygen concentration, safe and stable combustion can be continued even when the supply source of the combustion gas is abnormally changed and the oxygen content is suddenly changed.

[0021]

FIG. 1 is a longitudinal sectional side view showing an embodiment of a gas-fueled low-oxygen burner according to the present invention, and FIG. 2 is a transverse sectional view taken along the line II-II of FIG. In these figures, in order to avoid redundancy, the same reference numerals are given to the conventional elements described with reference to FIGS. 3 to 5 and detailed description is omitted.

As members newly described in FIGS. 1 and 2, (101) is a primary / secondary air communication port opening adjustment damper, (102) is a primary / secondary air communication port, and (103) is a damper. The operation rod, (104) is a damper operation motor, (10)
5) indicates a flame detection output transmitter / receiver, (106) indicates an oxygen concentration meter, and (107) indicates a flame stabilizer metal temperature meter.

In this embodiment, the primary air cylinder (03)
Primary and secondary air communication ports (102) that communicate between the inside and outside
The primary / secondary air communication port (102) is provided with an opening adjustment damper (101), and the primary air cylinder (0) is provided.
Primary air (2) blown into the furnace (13) from the outlet of (3)
The flow rate or flow rate in 3) is adjusted according to the combustion situation. Further, a flame detection output transmitter / receiver (105) for obtaining the output of the flame detector (08), a flame stabilizer (07)
Flame Holder Metal Temperature Meter (10
7) An oxygen concentration meter (106) for detecting the concentration of oxygen contained in the combustion air (22) is provided.

Regarding the operation of the burner having such a structure,
Next, a description will be given. First, the primary, secondary, and tertiary air flow rate adjusting dampers (09), (10), (11) are adjusted to the optimum flow rate distribution when the atmosphere (oxygen concentration = 21%) is used for combustion. Actually, each air cylinder (03), (04),
(05) The opening is adjusted so that the outlet flow velocity is set to the optimum flow velocity), and the primary / secondary air communication port opening adjustment damper (101)
Is fully closed, and starts combustion in a manner similar to the conventional one.

Next, the oxygen concentration of the combustion air (22) sent to the burner wind box (02) is measured by an oxygen concentration meter (10).
6), the primary and secondary air communication port opening adjustment dampers (10
Adjust the opening of 1). That is, the combustion air (22)
If the oxygen concentration is low, the ignition stability will deteriorate.
Open the secondary air communication port opening adjustment damper (101). Then, a part of the primary air (23) sent into the primary air cylinder (03) is converted into the primary / secondary air communication port (102).
From the primary air cylinder (03) and the annular cross-section passage formed by the secondary air cylinder (04) to mix with the secondary air (24). Therefore, the primary air cylinder (03)
The amount of primary air (23) blown into the furnace (13) as it is from the outlet is reduced, the flow velocity is also reduced, and the ignition stability is improved. Specifically, for example, the oxygen concentration in the combustion air (22) is 18% (dry, vol.
%) Or more, the primary / secondary air communication port opening adjustment damper (101) is fully closed, and if the concentration is 16% to 18%, 25%.
It is adjusted stepwise so that it is open, 50% open when the concentration is 15% to 16%, and fully open when the concentration is 15% or less.

[0026] The primary
Even if the secondary air communication port opening adjustment damper (101) is adjusted, if the flame ignition condition deteriorates and the output of the flame detector (08) becomes equal to or less than the predetermined value while the combustion is continued, the combustion is started. Regardless of the concentration of oxygen contained in the service air (22), the primary and secondary air communication port opening adjustment dampers (101) are opened to reduce the flow velocity at the outlet of the primary air cylinder (03) to improve the ignition condition of the flame. . When the output of the flame detector (08) reaches a predetermined value, it stops opening further.

If the metal temperature of the flame stabilizer (07) exceeds a predetermined value during the continuation of the combustion, the primary / secondary air communication port opening adjustment is performed regardless of the oxygen concentration in the combustion air (22). As the damper (101) is closed, the flow rate of the primary air (23) blown out of the primary air cylinder (03) is increased to reduce the metal temperature of the flame stabilizer (07). When the metal temperature of the flame stabilizer (07) falls below a predetermined value, the closing is stopped.

The primary and secondary air communication port adjusting dampers (10
If the above series of operations 1) is automated (manual operation is also possible), the primary, secondary and tertiary air flow rate adjusting dampers (09), (10) and (11) can be operated without operating. Stable burner operation is possible.

[0029]

According to the present invention, even if the concentration of oxygen contained in the combustion air (22) suddenly changes for some reason during the continuation of combustion, a safe operation can be performed automatically or simply by simple operation. Stable combustion can be continued.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view showing one embodiment of a gas fueled low oxygen burner of the present invention.

FIG. 2 is a cross-sectional view taken along the line II-II of FIG.

FIG. 3 is a vertical sectional side view showing an example of a conventional gas fuel fired low oxygen burner.

FIG. 4 is a front view taken along the line IV-IV of FIG. 3;

FIG. 5 is a cross-sectional view taken along the line VV of FIG. 3;

Figure 6 is a diagram showing the relationship between the air ratio and the NO _x generation amount of gaseous fuel.

FIG. 7 is a diagram showing the ignition limit of gas fuel in relation to the oxygen concentration in the primary air and the flow rate of the primary air.

FIG. 8 is a diagram showing the relationship between the primary air flow rate and the metal temperature of the flame stabilizer using the oxygen concentration in the primary air as a parameter.

[Explanation of symbols]

 (01) Boiler body (02) Burner-style box (03) Primary air cylinder (04) Secondary air cylinder (05) Tertiary air cylinder (06) Guide pipe (07) Flame stabilizer (08) Flame detector (09) Damper for adjusting primary air flow (10) Damper for adjusting secondary air flow (11) Damper for adjusting tertiary air flow (12) Burner throat refractory (13) Inside the furnace (14) Rich fuel gas nozzle (15) Rich fuel gas header ( 16) Rich fuel gas pipe (17) Light fuel gas nozzle (18) Light fuel gas header (19) Light fuel gas pipe (20) Rich fuel gas (21) Light fuel gas (22) Combustion air (23) Primary air (24) ) Secondary air (25) Light fuel premixed air (26) Tertiary air (27) Primary air passage (28) Light fuel premix chamber (29) Rich fuel flame (30) Light fuel flame (101) Primary / secondary air communication port opening adjustment damper (102) Primary / secondary air communication port (103) Damper operating rod (104) Damper operating motor (105) Flame detection output transmitter / receiver (106) Oxygen concentration meter (107) Flame Holder Metal Thermometer

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasushi Nakajima 1-1-1, Wadazakicho, Hyogo-ku, Kobe City Inside Mitsubishi Heavy Industries, Ltd. No. 1-1 Inside Mitsubishi Heavy Industries, Ltd.Kobe Shipyard (72) Inventor Satoru Fukui 1-1-1, Wadazakicho, Hyogo-ku, Kobe-shi Inside Mitsubishi Heavy Industries, Ltd.Kobe Shipyard (72) Inventor Masaharu Oguri 5, Fukahoricho, Nagasaki City Chome 717-1 Inside Nagahishi Engineering Co., Ltd. (56) References JP-A 52-62525 (JP, U) JP-A 61-121321 (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) F23C 11/00 F23D 14/00-14/10 F23N 5/02

Claims (2)

(57) [Claims] 1. A primary air cylinder disposed at an axis, a secondary air cylinder disposed coaxially around the same primary air cylinder, and a tertiary air cylinder disposed coaxially around the secondary air cylinder. A rich fuel gas nozzle mounted in the primary air cylinder, a light fuel gas nozzle mounted in an annular cross-sectional passage formed by the primary air cylinder and the secondary air cylinder, and a fuel gas nozzle provided in the primary air cylinder.
And the same as the primary and secondary air communication ports
An opening adjustment damper provided at the secondary / secondary air communication port, wherein the gas fuel injected from the rich fuel gas nozzle and the light fuel gas nozzle is burned by a gas having an oxygen concentration lower than that of the atmosphere, and In a gas fuel low-oxygen burner that forms a diffusion flame in the gas fuel injected from the fuel gas nozzle and a premixed flame in the gas fuel injected from the lean fuel gas nozzle, the flame detector
Output, flame stabilizer metal temperature and oxygen concentration of the above gas
A method for controlling a gas-fueled low-oxygen burner , comprising controlling the opening adjustment damper based on the degree . 2. When the output of the flame detector is less than a predetermined value.
Opens the opening adjustment damper regardless of the oxygen concentration.
The metal temperature of the flame stabilizer above a specified value.
In the above case, the opening adjustment dam
2. The method for controlling a gas-fueled low-oxygen burner according to claim 1, wherein the gas is closed .