JP2935639B2 - Gas burner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a gas burner .
It relates to a premixed gas burner. A relatively small-capacity gas burner, such as a small gas burner, or a pilot gas burner for ignition (a burner of the main body) of a premixed type (a type in which most of the air required for combustion is guided to a combustion start position by a different path from fuel gas). May be an oil burner as well as a gas burner) and the like are widely used in all industrial fields. In gas burners, certainty of ignition is strongly desired from the viewpoint of safety. Although the supply conditions of the fuel gas are various, the present invention relates to the arrangement of the spark plug which ensures ignition in response to all of these provided conditions.

[0002]

2. Description of the Related Art In a small-capacity premix gas burner , combustion is performed.
Combustion cylinder that forms an air passage for
Connecting the inner cylindrical body forming the passage and the tip of the inner cylindrical body.
For those equipped with a gas nozzle installed ,
An ignition plug (positive electrode) is arranged at the axial center of the fuel gas passage, and a high voltage is applied to blow a spark of an arc between the nozzle and the gas nozzle (negative electrode) to ignite the fuel gas (air-fuel mixture). Many have a structure. Conventionally, in the gas burner having this structure, the above-described gas nozzle has an axial direction in the fuel gas passage.
The tip of the ignition plug disposed in the direction center, was designed to come to the same position as the tip of the gas nozzle (Projection 0mm of the spark plug for a gas nozzle) As such, this case, and the supply pressure of the fuel gas, gas jet May not ignite depending on conditions such as the flow rate characteristics. Note that Japanese Patent Application Laid-Open
144207, JP-A-59-49426, and Jpn.
3-22328 (Japanese Utility Model No. 04-115218),
No. 01-142677 (Japanese Utility Model Application No. 03-87020)
There are various types of burners shown in
The type and model are different from the gas burner of the application
(At least in the axial direction of the gas nozzle inside the fuel gas passage)
Without a spark plug at the core)
The technical background is different.

[0003]

The supply of the fuel gas to the gas nozzle portion has been reduced due to the high supply pressure of the fuel gas, the large gas flow rate, and the closeness of the pressure regulating valve and the shutoff valve to the burner. If it increases rapidly, the paragraph number 0 described later
As described in 008 to 0011, at the place where the electric arc flies, the gas concentration is too high to cause ignition. Cause
Ignition arranged in the axial direction inside the fuel gas passage of the gas nozzle
Fuel gas in the axial flow around the plug and arc of the spark plug
Focusing on, in the present invention, in order to solve this problem, the slave
Next (0mm of the spark plug with respect to the gas nozzle
( G ) is to change the course of the electric arc to ensure ignition in response to all fuel gas supply conditions.

[0004]

Means for Solving the Problems The present invention, FIG. 1 or 2
As shown in FIG. 1, a gas burner includes an external combustion cylinder (external cylindrical body) 3 forming a combustion air passage, and an internal cylinder forming a fuel gas passage coaxially disposed inside the external combustion cylinder 3. In the axial direction with the tip of the inner cylindrical body 12.
The fuel gas passage communicating with the fuel gas passage of the internal tubular body
Gas nozzle 1 having a passage in the axial direction, a flange-shaped portion (flame holding plate) 10 or 11 provided at the tip of gas nozzle 1 for the purpose of flame holding after ignition, and a fuel gas passage inner shaft of gas nozzle 1
In the center of the direction , the inner circumference of the gas nozzle and the outer circumference of the spark plug
Sprays into the combustion area, with a space between it and the surface
Fuel gas flow (spouting forward from the gas nozzle opening)
Spark plug (electrode) that has
The provided, the position of the tip of the ignition plug 2 to be positive electrode, from the tip of the gas nozzle 1 as a negative electrode, a gas burner, characterized in that out forwardly 2 to 10 mm. In FIG. 1 or FIG. 2, reference numeral 4 denotes a gas flow, 5 denotes an air flow, and L denotes a protrusion 2 to 10 mm from the tip of the gas nozzle of the ignition plug. .

[0005]

In the forward direction from the gas nozzle opening, when the fuel gas is rapidly ejected, the gas becomes a gas rich region. However, the front of the flange portion (flame holding plate) provided at the tip of the gas nozzle on the outer peripheral side is always flammable. An air-fuel mixture is formed. In the present invention, the spark plug (positive electrode) disposed at the axial center of the fuel gas passage of the gas nozzle of the premixed gas burner is extended by 2 to 10 mm, and is extended forward from the tip position of the gas nozzle (negative electrode). Conventionally, the course where the arc flies
When the spark plug is 0 mm)
A spark discharge is generated in the above combustible mixture region.

[0006] gas nozzle has a normal shape in which a portion (flame holding plate) 10 of the flanged at its distal end as illustrated in FIG. When the supply of the fuel gas increases rapidly, the front end of the gas nozzle opening (the gas nozzle
The vicinity of the inner diameter tip portion becomes a gas rich region 6 where combustion does not occur. However, the fuel gas on the outer side (front of the flange portion of the gas nozzle) from the gas nozzle opening is formed by the flange portion. , Because there is no ejection of air and it is in a negative pressure state,
Gas is rewound from here, air is rewound from outside,
A combustible mixture region 8 is always formed.

[0007] The fuel nozzle of the gas nozzle of the premix gas burner
The length of the spark plug located at the axial center of the
As shown in FIG. 3, when a high voltage is applied by increasing the length of the spark plug by 2 to 10 mm with respect to the gas nozzle (providing an allowance of 2 to 10 mm for the gas nozzle), as shown in FIG. Paragraph number 000
The fuel gas and air fly toward the combustible mixture region 8 described in 6). In FIG. 3, 1 is a gas nozzle, 10 is a flange-shaped portion (flame holding plate) provided at the tip of the gas nozzle, 2 is an ignition plug, 3 is an external combustion cylinder, 12 is an internal cylindrical body that forms a fuel gas passage, and 4 is The flow of the fuel gas, 5 indicates the flow of air, and L indicates the start of the spark plug as in FIGS. 1 and 2, except that 6 is a 100% gas or gas rich region,
Represents an air 100% or air rich region, 8 represents a combustible mixture region, and 9 represents an electric arc (course of spark discharge).

[0008] The conventional arrangement relationship between the spark plug and the gas nozzle (the protrusion of the spark plug with respect to the gas nozzle is 0 mm) and
FIG. 4 shows the state of generation of an electric arc at the time of ignition and the state of the flow of fuel gas and air . In this case, the fuel gas (or a mixture of fuel gas and air) ejected from the gas nozzle causes the electric arc to be swept forward and follow an arcuate course when the flow velocity is increased. The discharge reaches the part. In addition, the supply of fuel gas is
When the flow rate of the fuel gas increases rapidly due to a sharp increase,
As described in the section above, the area in front of the gas nozzle opening is the gas rich area.
Therefore, the arc of the arc is generated in this
You. Fuel supply of the fuel gas, if the jet is gradual (gradual gas amount is increased), until the fuel gas is supplied, is in the gas nozzles for air is filled, it has been supplied with the air A combustible mixture is created by the gas and ignited by the spark discharge described above. In FIG. 4, the same reference numerals as those in FIG. 3 indicate the same parts.

However, when the supply pressure of the fuel gas is high, when the gas ejection amount is large, or when the shutoff valve is close to the burner and the piping capacity between them is small and overshoot due to gas outflow characteristics cannot be mitigated, The ejection of the fuel gas becomes abrupt (a sudden increase in the gas flow rate), and the flow of the fuel gas and the air is arranged as shown in FIG. 4 in a short time. That is, in the vicinity of the tip of the inner diameter of the gas nozzle, the gas becomes rich and deviates from the combustible air-fuel mixture region, so that even if the electric arc flies, it does not ignite.

FIG. 5 shows the change in the concentration of the fuel gas in the vicinity of the inner end of the gas nozzle (the arc portion) over time. The solid line 13 of the curve in FIG. 5 indicates that the gas flow rate is gradually increasing, and the dotted line 14 indicates that the gas flow rate is rapidly increasing ( overshoot flow rate characteristic). Shows that there is a large difference in The numerical value of the gas concentration (%) in FIG. 5 is for the case where the fuel gas is natural gas (13A), and the hatched portion indicated by reference numeral 15 indicates the combustible mixture concentration. That is, when the gas flow rate increases sharply as indicated by the dotted line, the time during which the combustible mixture region is formed is shorter than when the gas flow rate increases gradually as indicated by the solid line, indicating that ignition is difficult.

As described in the preceding paragraph (paragraph number 0010),
Depending on the fuel gas supply conditions, the gas is concentrated in a short time and it becomes difficult to ignite from the front end of the gas nozzle inner diameter to the front of the opening. However, in the present invention, a combustible mixture region is always formed regardless of this state. This causes the electric arc to fly to a course passing in front of the flange portion of the gas nozzle, thereby ensuring ignition.

The reason why the protrusion of the spark plug from the tip of the gas nozzle is limited to 2 to 10 mm in the present invention is as follows.
If it is less than 2 mm, the expected ignition performance cannot be obtained from the experimental results. If it exceeds 10 mm, sufficient ignition performance can be obtained and there is no change in the performance. However, if it is made too long (larger allowance), the tip of the spark plug will be located in the flame, causing high temperature and red heat. Cause burning trouble.

[0013]

EXAMPLES Examples of the present invention will be described below together with comparative examples. A gas burner as shown in FIG. 1 was used. Comparative Example In the case where the protrusion of the spark plug with respect to the gas nozzle was 0 mm No ignition occurred when the gas supply pressure was 500 mmAq or more. No ignition occurred when the distance from the shut-off valve was 350 mm or less in a pipe having an inner diameter of 8 mm. The spark did not ignite if the spark discharge was delayed for 3 seconds from the opening of the shut-off valve. When air (combustion air for the main burner) was flowed from the periphery of the ignition by-rotor at a flow rate of 20 m / sec, no ignition occurred. Example In the case where the allowance of the spark plug with respect to the gas nozzle was 5 mm, ignition was possible in all of the above cases.

[0014]

As is apparent from the above description, according to the present invention, the spark discharge (arc) formed between the spark plug and the gas nozzle always flies to the flammable mixture of fuel gas and air. Even if there is a sudden increase in gas flow rate, ignition is performed reliably, smooth operation, maintenance-free,
Safety is improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal side view of a gas burner according to the present invention.

FIG. 2 is a vertical sectional side view of a gas burner according to another example of the present invention.

FIG. 3 is a view showing the allowance of spark plugs of 2 to 10 according to the present invention.
It is a vertical side view of the gas burner which shows the course which an electric arc (spark discharge) flies when it is set to mm.

FIG. 4 is a longitudinal sectional side view of a conventional gas burner showing a course in which an electric arc flies when an allowance of a spark plug is 0 mm.

FIG. 5 is a diagram showing a change in the concentration of fuel gas in the vicinity of the inner end of a gas nozzle (an arc portion) over time in a gas burner.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Gas nozzle 2 Spark plug 3 External combustion cylinder (external cylindrical body) 4 Fuel gas flow 5 Air flow 6 Gas 100% or gas rich region 7 Air 100 % or air rich region 8 Combustible mixture region 9 Electric arc ( the flange-shaped portion (flame holding plate) 11 flange-shaped portion provided at the tip of the gas nozzle (flame holding plate) 12 internal cylindrical body 13 gradually increases in gas flow which is provided at the tip of the spark discharge of the course) 10 gas nozzle Flow characteristic curve at a certain time 14 Flow characteristic curve at a rapid increase in gas flow rate 15 Area of flammable mixture concentration 16 Ignition time when there is a gradual increase in gas flow rate 17 There is a rapid increase in gas flow rate Possible ignition time at the time L Lack of spark plug

Claims (1)

(57) [Claims] 1. A gas burner is an external combustion cylinder to form a combustion air passage, and an internal cylindrical body for forming a fuel gas passage which is arranged inside the external combustion cylinder coaxially, the inner tubular body Fuel gas passage of an internal cylindrical body connected to the tip in the axial direction
A gas nozzle having an axial fuel gas passage communicating with the
Between the inner peripheral surface of the gas nozzle and the outer peripheral surface of the spark plug, a flange-shaped portion provided at the tip of the gas nozzle for the purpose of flame holding after ignition, and the central portion in the axial direction of the fuel gas passage of the gas nozzle.
Fuel gas ejected into the combustion area while maintaining the space
Having a flow in the axial direction of the peripheral surface and including a spark plug serving as a positive electrode ,
A gas burner, wherein a tip position of the ignition plug serving as a positive electrode is set 2 to 10 mm forward from a tip end of a gas nozzle serving as a negative electrode.