JP2000130716A - Burner ignition torch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use low oxygen concentration air as an ignition torch air. SOLUTION: A fixed inner cylinder 140 and a movable inner cylinder 140b slidable axially of the fixed inner cylinder are disposed in an outer cylinder 117 of an ignition torch 100, and further a torch nozzle 19 and a flame insulator 18 are disposed in the fixed inner cylinder. Torch air is supplied from an inlet 144 into the fixed inner cylinder 140a to combust a fuel infected from the torch nozzle. Secondary air passes through an annular secondary flow passage 142 formed between an outer cylinder and the movable inner cylinder and is supplied from an injection hole 148 into the movable inner cylinder. When low oxygen concentration air is used as torch air, a flame formed in the flame stabilizer sometimes disappears in a short time owing to insufficient oxygen, but provided the movable inner cylinder is moved axially to permit secondary air to be supplied to the flame from the injection hole 148 at a position where flame temperature detected by a temperature sensor 143 exceeds ignition temperature of a fuel, flame failure is prevented from occuring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition torch for a burner which ignites fuel injected from a main burner of a furnace such as a boiler and forms an ignition flame for causing stable combustion of the main burner.

[0002]

2. Description of the Related Art In a boiler furnace or the like, an ignition torch for forming an ignition flame is provided separately from a main burner, and the flame formed by the ignition torch ignites fuel injected from the main burner to stabilize the main burner. Ensuring combustion is being performed.

FIG. 7 is a sectional view showing the structure of a gas-fired ignition torch for a main burner which is generally used, and FIG.
FIG. 8 shows a view in the direction of arrows VIII.

[0004] In Figs. 7 and 8, reference numeral 10 denotes an entire ignition torch. The ignition torch 10 includes a substantially cylindrical metal outer cylinder 17 and a torch nozzle 19 arranged along the center axis of the outer cylinder 17. As shown in FIG. 7, the torch nozzle 19 has a cylindrical shape having a fuel passage through which gaseous fuel (for example, propane or the like) flows. Has a plurality of pilot injection holes 21 respectively. Also,
A flame stabilizer 18 is arranged around the torch nozzle 19 at a position near the pilot injection hole 19. 7 and 8, reference numeral 24 denotes a spark plug for initial ignition of pilot fuel injected from pilot injection hole 21. Reference numeral 25 denotes main injection hole 2.
This is a flame detector for confirming the combustion of the fuel injected from 0.

[0005] Air for combustion of the torch 10 (hereinafter referred to as torch air) is supplied into the outer cylinder 17 to form an air flow toward the opening 17a as shown by an arrow in FIG. The pilot fuel injected from the pilot injection hole 21 is ignited by the spark of the ignition plug 24, and becomes a fire that burns the fuel injected from the main injection hole 20. The flame stabilizer 18 forms a stable low-speed circulation vortex immediately downstream of the flame stabilizer 18 of the torch air flow, and has a flame stabilizing function of stabilizing the ignition point of the fuel injected from the main injection hole 20. .

FIG. 9 is a view showing the arrangement of the ignition torch 10 and the main burner 4 in the boiler furnace 16. As shown in FIG. 9, the ignition torch 10 is connected to the burner nozzle 5 of the main burner 4.
Is disposed on the furnace wall 1 adjacent to the furnace wall. The combustion air of the main burner 4 is supplied from a supply source (not shown) into the wind box 3 surrounding the main burner 4, and is supplied from the wind box 3 through the periphery of the burner nozzle 4 into the furnace 16. Fuel injected from the burner nozzle 5 is ignited by a torch flame 15 formed by an ignition torch 10, and forms a main burner flame 14 in a furnace 16. In FIG. 9, 11 is a torch air supply pipe, 1
2 is a main burner fuel pipe, and 13 is a torch fuel pipe.

[0007] As shown in Fig. 7, the tip of the torch nozzle 19 of the ignition torch 10 is located inside the opening 17a of the outer cylinder 17, and the fuel injected from the torch nozzle 19 is only oxygen supplied by the torch air. First burns in the outer cylinder 17, and then burns outside the outer cylinder 17 using oxygen supplied by the main burner combustion air, and
A torch flame 15 extending from a into a furnace 16 is formed.

[0008]

The ignition torch for a burner is required to maintain a torch flame capable of igniting the main burner fuel in any case. For this purpose, the ignition torch must be able to withstand disturbances such as contact of the main burner combustion air with a high-speed air flow and rapid changes in the pressure in the furnace, and always provide a stable flame. In order to maintain a stable torch flame without being affected by such a disturbance, the pressure difference between the inlet and the outlet of the ignition torch of the torch air (that is, the torch air flow rate) is maintained within a certain range, and the torch is further increased. Torch air amount to fuel amount (air ratio)
Is also required to be kept within a certain range,
It is experimentally known.

FIG. 10 shows fresh air (atmosphere, ie, air having an oxygen concentration of about 20%) as torch air.
FIG. 4 is a diagram showing the relationship between the ignition characteristics of a general ignition torch, the torch air differential pressure, and the air ratio in the case where is used. FIG.
, The vertical axis is the differential pressure between the inlet and outlet of the torch air (mmAq)
And the horizontal axis represents the air ratio λ (the ratio between the amount of oxygen supplied by the torch air and the theoretical amount of oxygen required to completely burn the fuel). FIG. 10 shows a case where liquefied petroleum gas (LPG, propane 90%) is used as a torch fuel.

As shown in FIG. 10, generally, stable ignition performance of the ignition torch is obtained when the torch air differential pressure is about 50 to 100 mmAq and the air ratio λ is 0.2.
From 0.5 to 0.5. That is, if the torch air differential pressure is larger than this range, poor ignition or flame blowout due to excessive air flow velocity in the torch occurs. If the differential pressure is smaller than the above, there is a problem that the torch flame becomes unstable due to an increase in the influence of disturbance due to insufficient flow velocity. On the other hand, when the air ratio is 0.2 or less, oxygen becomes insufficient and the torch fuel does not ignite, or even when ignited, the flame disappears in the torch outer cylinder, and in the region where the air ratio is 0.5 or more, Since the amount of air is excessive and the torch fuel is diluted, there is a problem that ignition does not occur. For this reason, when fresh air is used as the torch air, it is necessary to adjust both the torch air differential pressure and the air ratio within the above range in order to form a stable torch flame.

However, in recent years, the exhaust gas recirculation (GR) for mixing the combustion exhaust with the main burner combustion air has been increasing in boiler furnaces and the like in order to improve the exhaust properties.
In addition, the mixing ratio (GR ratio) of the exhaust gas tends to increase, and the amount of exhaust gas of 20% or more of the main burner combustion air is often mixed. When such a large amount of exhaust gas recirculation is performed, the oxygen concentration of the main burner combustion air becomes considerably lower than that of fresh air. Some boilers used in a combined cycle of a gas turbine / boiler unit or the like use the gas turbine exhaust as it is as the main burner combustion air. In this case, the oxygen concentration in the main burner combustion air is about 13%. To a degree.

However, in the conventional ignition torch, if air having such a low oxygen concentration is used, there arises a problem that a stable torch flame cannot be maintained.

As described above, in order to maintain a stable torch flame, it is necessary to maintain both the torch air differential pressure and the air ratio (oxygen amount) within a certain range. However, when air with a low oxygen concentration is used as the torch air, if the same amount of torch air is supplied as in the prior art, the air ratio will be small, and it will not be possible to ignite with the ignition torch due to lack of oxygen or the torch after ignition. Flame extinction will occur in the interior. On the other hand, if an attempt is made to increase the air ratio to supply a sufficient amount of oxygen to prevent this, the amount of torch air will be excessively large as a whole, and the fuel will be diluted, making it impossible to ignite in the torch or causing the torch air to flow. There is a problem that the flow velocity becomes excessive and the flame blows out even if the ignition occurs.

Therefore, in the conventional ignition torch, even when the exhaust gas is recirculated to the main burner, the combustion air having the same low oxygen concentration as that of the main burner cannot be used, and fresh air must be separately supplied as the torch air. was there.

FIG. 11 is a diagram schematically showing a conventional torch air supply system when exhaust gas is recirculated to the main burner. As shown in FIG. 11, the exhaust of the boiler furnace was
From the air heater 33 through the air heater 33. Further, the fresh air for combustion is pumped from the atmosphere by a forced air ventilator 30, passes through an air heater 33, exchanges heat with the exhaust air, and is mixed with the exhaust air supplied from a furnace outlet by a recirculating gas ventilator 32 to mix with low oxygen. The combustion air of the concentration is supplied from the main burner air pipe 36 to the main burner 4 via the wind box 3. In this case, as described above, the conventional ignition torch cannot use the combustion air having a low oxygen concentration of the main burner 4, so that it is necessary to supply the fresh air before the exhaust gas downstream of the air heater 33 as the torch air. Therefore, the ignition torch air pipe 11 must be provided separately from the main burner air pipe 36 from the downstream side of the air heater 33 to the ignition torch 10. For this reason, there has been a problem that the piping system becomes complicated and the construction cost of a boiler or the like increases due to an increase in piping cost.

In view of the above problems, the present invention makes it possible to use low-oxygen-concentration air as combustion air, and to use a combustion air system for an ignition torch even when recirculating exhaust gas to the main burner. It is intended to provide an ignition torch.

[0017]

According to the first aspect of the present invention, there is provided an ignition torch for a burner for forming a flame for igniting a main burner, the outer cylinder forming an air flow path for torch combustion, A torch nozzle for injecting fuel into the torch combustion air flow in the outer cylinder, flame forming means for forming a torch flame in the outer cylinder with the injected fuel and torch combustion air, A secondary air supply means for supplying secondary air for combustion at a predetermined secondary air supply position along an outer cylinder axis in a cylinder is provided.

According to the second aspect of the present invention, the secondary air supply means has means for changing the secondary air supply position along the axial direction of the outer cylinder. Is provided.

According to a third aspect of the present invention, there is provided the burner ignition torch according to the first or second aspect, wherein the torch combustion air is air having an oxygen concentration lower than that of the atmosphere.

According to the invention described in claim 4, the secondary air supply position is set at a position where the temperature of the torch flame formed by the torch combustion air becomes equal to or higher than a predetermined value. Or an ignition torch for a burner according to item 3.

According to the fifth aspect of the present invention, the torch combustion air is supplied from the same air supply source as the combustion air supplied to the main burner. 2. An ignition torch for a burner according to claim 1.

According to a sixth aspect of the present invention, there is provided a burner ignition torch for forming a flame for main burner ignition,
An outer cylinder, an inner cylinder extending in the outer cylinder to form a torch combustion air flow path, a torch nozzle for injecting fuel into the torch combustion air flow in the inner cylinder, and an injected fuel and torch combustion Flame forming means for forming a torch flame in a cylinder by air, a secondary air flow path for combustion formed between the inner cylinder and the outer cylinder, and the formed and formed on a wall surface of the inner cylinder. A secondary air supply port for injecting secondary air for combustion into the flame, and moving the inner cylinder in the axial direction of the outer cylinder with respect to the outer cylinder to shift the secondary air supply position for combustion to the flame in the axial direction of the outer cylinder. Means for varying along the burner ignition torch.

Hereinafter, the operation of the invention described in each claim will be described.

According to the first aspect of the present invention, secondary air is supplied to a torch flame formed in the outer cylinder of the ignition torch at a predetermined position in the outer cylinder. For example, when air with a low oxygen concentration is used as the torch air, if the air flow rate in the torch is set equal to that of fresh air, the torch fuel will ignite, but the generated flame will be out of oxygen in the torch outer cylinder. Have the problem of disappearing. In the present invention, even when the air flow velocity in the torch is set equal to the conventional one, oxygen is supplied to the flame by the secondary air in the outer cylinder, so that the flame disappears in the outer cylinder due to lack of oxygen. The prevented and stable torch flame extends outside the outer cylinder. In this case, it is preferable that the secondary air supply position is set, for example, upstream of a position where the flame after ignition disappears due to lack of oxygen, and oxygen is supplied to the flame before the flame disappears.

Further, in the invention of claim 2, according to claim 1
Means are provided for changing the secondary air supply position of the secondary air supply means along the axial direction of the torch outer cylinder. The position where the fuel once ignited in the torch disappears due to lack of oxygen differs depending on the amount of oxygen in the torch air, the torch fuel used, and the like. In the present invention, the secondary air supply position can be changed along the outer cylinder axis direction, so that even when the amount of oxygen of the torch air or the fuel used is different, the secondary air is supplied to an appropriate position to prevent the flame from disappearing. It is possible to do.

Further, in the invention of claim 3, air having a low oxygen concentration is used as the torch air in the invention of claim 1 or 2. That is, according to the present invention, a stable torch flame is generated even when air having a low oxygen concentration is used as the torch air.

In the invention of claim 4, the temperature of the torch flame formed in the cylinder in claim 2 or 3 is set at a position where the temperature becomes a predetermined value. For example, when the flame formed by ignition in the cylinder disappears due to lack of oxygen, the flame temperature decreases toward the disappearance position after ignition. For this reason, the position where the secondary air is supplied to prevent the flame from disappearing is a position where the flame temperature is a temperature at which a flame can be formed again by supplying oxygen, that is, a position where the flame temperature is equal to or higher than the ignition temperature of the fuel. There is a need. In the present invention,
Since the secondary air supply position is set at a position where the flame temperature is equal to or higher than a predetermined value (for example, the ignition temperature of fuel), it is possible to reliably prevent the flame from disappearing due to lack of oxygen. In addition, the flame temperature referred to in the present invention includes the temperature of the non-flame flame.

Further, in the invention according to claim 5, in the invention according to any one of claims 2 to 4, the torch air is supplied from the same air supply source as the combustion air of the main burner. It is not necessary to provide a separate piping system for the main burner combustion air.

On the other hand, in the invention of claim 6, the secondary air is supplied to the torch flame from the inner cylinder wall surface through the secondary air flow path formed between the inner cylinder and the outer cylinder. Further, since the inner cylinder is movable relative to the outer cylinder in the axial direction of the outer cylinder, it is possible to change the position for supplying the secondary air to the flame in the outer cylinder along the axial direction of the outer cylinder. Become.

[0030]

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

FIG. 1 is a sectional view similar to FIG. 7, showing an embodiment of the ignition torch for a burner of the present invention. FIG.
7, the same reference numerals as in FIG. 7 represent the same elements as in FIG.

In FIG. 1, reference numeral 100 denotes the entire ignition torch. In this embodiment, the ignition torch 100 includes a substantially cylindrical metal outer cylinder 117 and an inner cylinder 140 arranged concentrically with the outer cylinder 117. In the inner cylinder 140,
7, a torch 19, a flame stabilizer 18, a spark plug 24
And a flame detector 25. In the present embodiment, the inner cylinder 140 is a fixed inner cylinder 140a and a fixed inner cylinder 140a.
A movable inner cylinder 140b mounted around the distal end and slidable in the axial direction with respect to the fixed inner cylinder 140a. A plurality of secondary air ejection holes 148 for ejecting secondary air, which will be described later, in the radial direction of the inner cylinder are arranged on the peripheral wall near the distal end of the movable inner cylinder 140b. In FIG. 1, reference numeral 143 denotes 2
This is a temperature sensor for detecting a flame temperature, for example, a thermocouple, which is arranged on the wall surface of the movable inner cylinder near the next air ejection hole 143.

In this embodiment, primary air (torch air) for combustion of fuel injected from the torch nozzle 19 is supplied from the torch air inlet 144 provided on the outer circumference of the outer cylinder 117 to the outer cylinder 117 and the fixed inner cylinder 140a. The gas enters the annular torch air chamber 144a formed therebetween, and flows from the torch air chamber 144a through the plurality of primary air inlets 146 opening to the peripheral wall of the fixed inner cylinder into the fixed inner cylinder 144a. The annular torch air chamber 144a is divided by a partition 149 into a secondary air chamber 15 described later.
2 is separated. The torch air (primary air) flowing into the fixed inner cylinder 144a is supplied to the flame stabilizer 18 and the fixed inner cylinder 144.
a between the fixed inner cylinder 144a and the movable inner cylinder 1
44b and the inside of the outer cylinder 117,
It gushes into the furnace from 7a.

In this embodiment, a secondary air inlet 145 is provided on the outer periphery of the outer cylinder 117 in addition to the torch air inlet 144. The secondary air flows from the secondary air inlet 145 into an annular secondary air chamber 152 defined by the outer cylinder 117, the fixed inner cylinder 140a, and the partition 149. The movable inner cylinder 144b has sliding flanges 141a and 141b at both ends thereof in sliding contact with the inner wall of the outer cylinder 117.
Outer wall, inner wall of outer cylinder 117 and sliding flanges 141a, 141
1b forms an annular secondary air flow path 142. 2
The secondary air in the secondary air chamber 152 is supplied to the sliding flange 141a.
Flows into the secondary air flow path 142 from the communication hole 147 provided in the secondary air outlet 142 near the tip of the movable inner cylinder 140b.
From 48, it is jetted in the radial direction of the inner cylinder 140b.

The movable inner cylinder 140b is connected to an appropriate drive mechanism (not shown) via a rod 170. Thereby, by operating the drive mechanism from the outside, the movable inner cylinder 140b is moved along the outer cylinder 117 axial direction while sliding with the outer wall of the fixed inner cylinder 140a and the inner wall of the outer cylinder 117 via the sliding flanges 141a and 141b. It is possible to make it. In the present embodiment, the position of the secondary air ejection hole 148, that is, the secondary air supply position can be changed along the axial direction of the outer cylinder by moving the movable inner cylinder 140b along the axial direction. ing.

In the present embodiment, the torch 100 is used as a main burner for performing exhaust gas recirculation, and the torch air and the secondary air are air having the same low oxygen concentration as the combustion air of the main burner. In this embodiment, the fixed inner cylinder 1
The differential pressure (torch air flow rate) between the inlet and outlet of the fixed inner cylinder 140a of the torch air (primary air) supplied into the inside 40a is set to be substantially equal to the conventional one (for example, in the range of 50 to 100 mmAq).

In this case, the fuel injected from the torch nozzle 19 is ignited by the spark plug 24 and once forms a flame by the flame stabilizer 18, but oxygen is supplied to the flame by torch air (primary air) having a low oxygen concentration. If it is performed only by flame, it becomes difficult to maintain the flame due to the shortage of oxygen, and the flame once formed disappears from the flame stabilizer 18 with a certain length, and it is not possible to form a flame extending outside the outer cylinder opening 117a. Further, if the pressure difference between the inlet and outlet of the fixed inner cylinder of the torch air (primary air) is increased beyond the above range in order to supply sufficient oxygen, the torch air flow rate becomes excessively large, making it impossible to ignite or difficult to form a flame.

Therefore, in the present embodiment, the pressure difference between the inlet and outlet of the fixed inner cylinder is set in a range (for example, 50 to 100 mmAq) that enables stable flame formation in the flame stabilizer 18.
Before the flame formed by the torch air disappears due to lack of oxygen, secondary air is supplied to the flame from the secondary air ejection hole 148 of the movable inner cylinder 140b to prevent the flame from disappearing.

In this case, the secondary air supply position needs to be a position where the flame (or combustion gas) temperature detected by the temperature sensor 143 is higher than the ignitable temperature. That is, when the gas temperature is equal to or higher than the ignition temperature (for example, 900 ° C.), even if the flame has once disappeared and is in the state of non-flame flame,
This is because, if oxygen is supplemented, the combustion gas self-ignites again, but if the gas temperature becomes lower than the ignition temperature, the gas cannot self-ignite. Therefore, in the present embodiment, the movable inner cylinder 140b is moved along the axial direction of the outer cylinder by the drive mechanism, and the secondary air supply position is set to a position where the temperature detected by the temperature sensor 143 becomes a predetermined value (ignitionable temperature). (The position of the secondary air outlet 148) is adjusted. As a result, a sufficient amount of oxygen is supplied to the flame in the outer cylinder, the loss of the flame in the outer cylinder 117 is prevented, and even when air having a low oxygen concentration is used as torch air. A stable flame extending from the outer cylinder opening 117a to a sufficient length is formed.

FIG. 2 is an experimental result showing a flame stabilization condition when secondary air is supplied into the outer cylinder as in the present embodiment. In FIG. 2, the vertical axis indicates the differential pressure (mmAq) of the torch air (primary air) at the entrance and exit of the fixed inner cylinder 140a, and the horizontal axis indicates the oxygen concentration (%) of the used torch air and secondary air. The point numbers represent the air ratio of the torch as a whole, that is, the ratio of the total amount of oxygen supplied by the torch air and the secondary air to the theoretical amount of oxygen required to completely burn the fuel. Also in FIG. 2, liquefied petroleum gas (LPG, propane 90%) is used as a torch fuel.
You are using

As shown in FIG. 2, in the ignition torch of this embodiment, when the torch air differential pressure is set in the range of 50 to 100 mmAq and the air ratio of the entire torch is set in the range of about 0.2 to 0.5, Reduce the oxygen concentration of the torch air and secondary air to 1
It was confirmed that a stable torch flame could be formed even when the temperature was significantly reduced to about 2%.

FIG. 3 is a view similar to FIG. 9 showing an arrangement on the furnace outer wall when the ignition torch of the embodiment of FIG. 1 is applied to a main burner for recirculating exhaust gas, and FIG. 4 is a view similar to FIG. It is a similar air supply system diagram. 3 and 4, the same reference numerals as those in FIGS. 9 and 11 represent similar elements. As shown in FIGS. 3 and 4, in the present embodiment, the torch air and the secondary air are supplied by the torch air pipe 111 branched from the main burner air pipe 36 after the exhaust gas is mixed, and the torch air flow control valve is used. After the flow rate is adjusted by 154 and the secondary air flow control valve 155, the air is supplied to the torch 100 from the torch air inlet 144 and the secondary air inlet 145 of each ignition torch 100. For this reason, it is possible to set the branch position of the torch air pipe 111 from the main burner air pipe 36 to a position close to the ignition torch 100,
The pipe length of the pipe 111 can be shortened, and the piping system can be simplified.

Next, a second embodiment of the ignition torch of the present invention will be described with reference to FIGS. 1 to 4
In the embodiment, the torch air and the secondary air are supplied to the ignition torch 100 by the torch air pipe 111 branched from the air pipe 36 for the main burner. On the other hand, this embodiment is different in that the torch air piping can be completely eliminated by supplying the torch air and the secondary air from the wind box of the main burner to the ignition torch.

FIG. 5 is a sectional view similar to FIG. 1 showing the structure of the ignition torch of the present embodiment. 5, the same reference numerals as those in FIG. 1 represent the same elements.

The ignition torch 200 of the embodiment shown in FIG.
Has almost the same structure as the ignition torch 100,
The difference is that no piping is connected to the torch air inlet 244 and the secondary air inlet 245 and the torch air inlet 244 and the secondary air inlet 245 are opened in the wind box 3. The torch air inlet 244 and the secondary air inlet 245 are provided with a plate-shaped torch air flow rate adjustment damper 254 and a primary air flow rate adjustment damper 255, respectively. Each of the flow rate adjusting dampers 254 and 255 has a rotating shaft 25 connected to an opening adjustment mechanism (not shown).
7, the air flow rate is adjusted by changing the opening areas of the torch air inlet 244 and the secondary air inlet 245. In the present embodiment, the damper 2
The degree of opening between 54 and 255 can be adjusted manually or by an appropriate actuator from outside the wind box 3. In FIG. 5, reference numeral 37 denotes an outer plate of the wind box 3, and 256 denotes a torch mounting plate for fixing the torch 200 to the wind box outer plate 37 with bolts or the like. As described above, the combustion air for the main burner having a low oxygen concentration is sent to the wind box 3 from the main burner air pipe 36 under pressure, and the inside of the wind box 3 is maintained at a constant positive pressure. Therefore, by adjusting the flow control dampers 254 and 255 from the outside of the wind box 3 to an appropriate opening, the amounts of the torch air and the secondary air can be set to appropriate values.

FIG. 6 is a view similar to FIG. 3 showing an arrangement on the outer wall of the furnace when the ignition torch of the present embodiment is applied to a main burner for recirculating exhaust gas. As shown in FIG. 6, in the present embodiment, the torch air and the secondary air are supplied from the inside of the wind box 3 for the main burner 5, so that the piping to the ignition torch 200 becomes only the torch fuel piping 13 and the air piping. The system is greatly simplified and piping costs are reduced.

In each of the above embodiments, the movable inner cylinder 1
The drive mechanism for moving the 44b along the axial direction may be manually operated by an operator so that the temperature sensor detection value becomes a predetermined temperature, or may be automatically controlled based on the temperature sensor detection value. Is also good.

For example, once the oxygen concentration of the torch fuel or torch air (main burner combustion air) is set to an optimum value, it does not fluctuate significantly during the subsequent operation. Therefore, in such a case, for example, the operator manually operates the rod 170 of the movable inner cylinder 144b while monitoring the indicated value of the temperature sensor 143 and then moves the movable inner cylinder 144b to an appropriate position. After the setting, the rod 170 may be fixed.

When the main burner air oxygen concentration fluctuates during operation, the rod 170 is connected to a servo mechanism, and the servo mechanism is feedback-controlled based on the output of the temperature sensor 143, so that an appropriate value is always obtained. It is also possible to control the movable inner cylinder 144b to the position.

In each of the above embodiments, the case where gas fuel is used as the ignition torch fuel has been described as an example. However, it is needless to say that the present invention can be applied to an ignition torch using liquid fuel.

[0051]

According to the invention described in each claim, by supplying secondary air to a predetermined position in the outer cylinder of the ignition torch, air with a low oxygen concentration can be used as torch air. . For this reason, the invention described in each claim has a common effect that the air piping can be simplified and the piping cost can be reduced when the present invention is used for a burner that performs exhaust gas recirculation.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a structure of an embodiment of a burner ignition torch of the present invention.

FIG. 2 is an experimental result showing a flame stabilization condition of the ignition torch of the embodiment of FIG.

FIG. 3 is a diagram showing an arrangement of the ignition torch of the embodiment of FIG. 1 on a furnace outer wall.

4 is an air supply system diagram of a boiler using the ignition torch of the embodiment of FIG.

FIG. 5 is a sectional view similar to FIG. 1, showing the structure of another embodiment of the burner ignition torch of the present invention.

6 is a view similar to FIG. 3, showing the arrangement of the ignition torch of the embodiment of FIG. 5 on the furnace outer wall.

FIG. 7 is a cross-sectional view showing the configuration of a conventional general gas-fired ignition torch for a main burner.

8 is a view in the direction of arrows VIII-VIII in FIG. 7;

FIG. 9 is a view showing an arrangement of a conventional general ignition torch on a furnace outer wall.

FIG. 10 is a diagram showing ignition characteristics of a general ignition torch.

FIG. 11 is a conventional general torch combustion air supply system diagram of a boiler that performs exhaust gas recirculation.

[Explanation of symbols]

 19 ... Torch nozzle 100, 200 ... Ignition torch for main burner 117 ... Outer cylinder 140a ... Fixed inner cylinder 140b ... Movable inner cylinder 148 ... Secondary air ejection hole 143 ... Temperature sensor

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideaki Aiki 1-1-1, Wadazakicho, Hyogo-ku, Kobe-shi, Hyogo Mitsubishi Heavy Industries, Ltd. 1-1-1 Wadazakicho, Ward Mitsubishi Heavy Industries, Ltd., Kobe Shipyard (72) Inventor Shoji Watanabe 1-1-1, Wadasakicho, Hyogo-ku, Kobe, Hyogo Prefecture Mitsubishi Heavy Industries, Ltd.Kobe Shipyard (72) Invention Person Satoru Fukui 1-1-1, Wadazakicho, Hyogo-ku, Kobe-shi, Hyogo Prefecture Inside Kobe Shipyard, Mitsubishi Heavy Industries, Ltd. (72) Inventor Masaharu Oguri 5-717-1, Fukaboricho, Nagasaki-shi, Nagasaki Prefecture Terms (reference) 3K019 AA02 BA02 BB04 BD02 CC02

Claims (6)

[Claims] 1. An ignition torch for a burner for forming a flame for ignition of a main burner, comprising: an outer cylinder forming an air flow path for torch combustion; and a torch nozzle for injecting fuel into a torch combustion air flow in the outer cylinder. Flame forming means for forming a torch flame in the outer cylinder by using the injected fuel and torch combustion air; and supplying predetermined secondary air along the outer cylinder axis to the formed flame in the outer cylinder. And a secondary air supply means for supplying secondary air for combustion at a position. 2. An ignition torch for a burner according to claim 1, wherein said secondary air supply means has means for changing said secondary air supply position along the outer cylinder axis direction. 3. The burner ignition torch according to claim 1, wherein the torch combustion air and the secondary air are air having an oxygen concentration lower than that of the atmosphere. 4. The burner ignition torch according to claim 2, wherein the secondary air supply position is set at a position where a temperature of a torch flame formed by the torch combustion air is equal to or higher than a predetermined value. . 5. The air supply source according to claim 2, wherein the torch combustion air and the secondary air are supplied from the same air supply source as the combustion air supplied to the main burner. An ignition torch for a burner according to item 1. 6. An ignition torch for a burner for forming a flame for ignition of a main burner, comprising: an outer cylinder; an inner cylinder extending in the outer cylinder to form a torch combustion air flow path; A torch nozzle for injecting fuel into the torch combustion air flow, flame forming means for forming a torch flame in the cylinder by the injected fuel and torch combustion air, and formed between the inner cylinder and the outer cylinder. A secondary air flow path for combustion, a secondary air supply port formed on a wall surface of the inner cylinder and injecting secondary air for combustion into the formed flame, Means for moving in the cylinder axis direction to change the combustion secondary air supply position for the flame along the outer cylinder axis direction.