JPH0619956Y2 - Pilot burner for radiant tube burner of continuous annealing furnace - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a pilot burner equipped with a radiant tube burner for a continuous annealing furnace, having high reliability and long life.

[Conventional technology]

In a heating furnace equipped with a large number of burners, such as a continuous annealing furnace for metallic steel strips, it is the most important point for safe operation that all the burners burn stably. If one of the burners in it misfires for some reason, the operator must take action to quickly close the valve of that burner. However, visually checking the combustion state of many burners causes an excessive load on the operator and may cause an accident.Therefore, indirectly and remotely, the situation of fire, that is, "burning" or "misfire" is detected. There is a great demand for a means for detecting whether or not it is, and various means have been proposed ("Industrial heating", Vol.24, No.4, 1987/7, Japan Industrial Reactor Association, P, 84, flame rod, Optical sensor).

FIG. 5 shows a typical example of a pilot burner that meets the above-mentioned demand. In this pilot burner 1, the fuel supplied from the fuel supply port 4 is injected from the nozzle tip 2 and the flame holding cylinder 3 The flame 6 is formed. On the other hand, the frame rod 5 is inserted into the flame holding cylinder 3 through a frame rod insertion port 7 provided on the side surface of the flame holding cylinder 3 and fixed by an insulating support 8.

Here, when a predetermined voltage is applied between the frame rod 5 and the pilot burner 1 from the constant voltage generator 9, the flame 6
The ions inside the flame rod 3 and the tip 5a of the frame rod 5
Alternatively, the presence or absence of the flame 6 can be detected by moving between the nozzle tips 2 and flowing a weak current, and detecting the weak current with the current detector 10.

[Problems to be solved by the device]

However, such a conventional pilot burner has a problem that the bent portion at the tip of the frame rod is broken after about one year of use, and flame detection cannot be performed. As a result of investigating the cause of the breakage, it was presumed that the thermal stress was concentrated in the strained portion generated in the bent portion and the breakage occurred.

The present invention has been made in view of such conventional problems, and an object thereof is to solve the above problems by dividing a frame rod into an insertion portion and a longitudinal portion thereof.

[Means for Solving the Problems]

Whether or not flame is formed in the flame holder of the pilot burner for the radiant tube burner arranged in the continuous annealing furnace,
In a pilot burner for detecting and monitoring an ionic current in a flame by a voltage applied via a frame rod, the frame rod includes a longitudinal rod arranged along an outer longitudinal direction of the pilot burner and a flame holding cylinder side surface. As a split body with the insertion rod inserted into the flame holding cylinder,
A connecting member made of a conductive metal attached to each connecting portion of each divided body is fixed by welding.

[Action]

Since the present invention has the above-described structure, the frame rod does not have a bent portion at the insertion portion as in the conventional case, and therefore stress acting in the bending direction does not occur during expansion and contraction due to heat. That is, since the longitudinal rods and the insertion rods, which are the two divided portions of the frame rod, are both straight and do not cause bending distortion, no breakage accident occurs.

〔Example〕

The present invention will be described below with reference to the drawings. 1 to 3
The figure shows an embodiment of the present invention. The same parts as those in the conventional example are designated by the same reference numerals, and duplicate description will be omitted.

FIG. 1 is a side view of an essential part of the embodiment, in which 11 is a longitudinal rod of a frame rod arranged along the main body of the pilot burner 1, and 13 is an insertion part of the frame rod into the flame holding cylinder 3. This rod is a rod, and the longitudinal rod 11 and the insertion rod 13 are connected by a connector 12 made of a conductive metal. This is specifically shown in the second, third and fourth
FIG. 12 is a view showing the connector 12A of FIG.
₁ and 12A ₂ are butt-joined at a right angle and welded to L
In this case, the longitudinal rods 11A and the insertion rods 13A of the frame rods are welded and fixed to each other as shown in the figure. Figure 3 is a obtained by a connector 12B by welding the two and tube 12B ₁ and 12B ₂ similarly to FIG. 2 to L-shaped, the two tubes 12B ₁ and 12
B ₂ is provided with a screw on each of the longitudinal rod 11B and the insertion rod 13B of the frame rod so that they can be screwed together.

Since the above-mentioned connecting tools 12A and 12B are all made of metal having good conductivity, they form a frame rod that is also electrically integrated, and therefore the constant voltage device 9 connects the frame rod 11 and the pilot burner 1 together. When a predetermined voltage is applied between the ions, the ions in the flame 6 move between the tip of the frame rod insertion portion 13 and the flame holding cylinder 3 or the nozzle tip 2 and a weak current flows, and this weak current is detected by the current detector. The presence / absence of the flame 6 can be detected by the detection at 10.

Next, an example in which the pilot burner of the present invention shown in FIG. 1 is adopted as a radiant tube burner in a continuous annealing furnace for metallic steel strips will be described. This continuous annealing furnace was equipped with 180 radiant tubes, and all of them used the pilot burner of the conventional example shown in FIG. 5, but as described in the above problem, the rod tip portion was broken, and for one year. The 20 frame rods corresponding to about 10% were replaced. However, when the pilot burner of the present invention shown in Fig. 1 was adopted for all radiant tubes, it was found that the continuous 3 x 10 ⁴
There is no damage to the frame rod over time, and good ignition and flame detection are achieved.

[Effect of device]

As described above, according to the present invention, since the frame rod is divided and there is no bent portion, thermal stress concentrates on the strain generated in the bent portion as in the conventional case, and the flame holding cylinder of the frame rod is The pilot burner had high reliability and long life without any accident such as breakage of the insertion part.

[Brief description of drawings]

FIG. 1 is a side view of a main part of an embodiment according to the present invention,
FIG. 3 and FIG. 3 are sectional views of essential parts of different embodiments according to the present invention, and FIG. 4 is a fragmentary side view of the prior art. 1 ... Pilot burner, 3 ... Flame holding cylinder, 11 ... Frame rod, 11A, 11B, ... Longitudinal rod, 12
...... Connecting tools, 13A, 13B, …… Insertion rod.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenichi Fujita, 1 Kawasaki-cho, Chiba, Chiba Prefecture, Chiba Steel Works Co., Ltd. (72) Kuniaki Sato, 1 Kawasaki-cho, Chiba, Chiba Iron Works, Chiba Steel In-house (72) Inventor Hiroyuki Nakamura 2-53, Shirute, Tsurumi-ku, Yokohama-shi, Kanagawa Japan Furnace Industries Co., Ltd. (56) References: Showa 54-64337 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. The presence / absence of flame formation in a flame holding cylinder of a pilot burner for a radiant tube burner arranged in a continuous annealing furnace is monitored by detecting an ion current in the flame by a voltage applied via a frame rod. In the pilot burner, the frame rod is a divided body of a longitudinal rod arranged along the outer longitudinal direction of the pilot burner and an insertion rod inserted into the flame holding cylinder from the side surface of the flame holding cylinder. A pilot burner for a radiant tube burner of a continuous annealing furnace, characterized in that a connecting member made of a conductive metal attached to each of the connecting portions of the above is fixed by welding.