JPH0530158Y2 - - Google Patents

Description

[Detailed description of the invention] "Industrial application field" This invention relates to a glass melting furnace for a radioactive waste liquid vitrification plant, and more specifically, an improvement of an off-gas discharge pipe that sucks and discharges off-gas generated inside the glass melting furnace. Regarding.

``Prior Art'' Generally, in a so-called vitrification plant that vitrifies high-level radioactive waste liquid generated at nuclear power generation facilities, etc., as in the conventional example shown in FIG. The radioactive waste liquid and glass material are fed into the glass melting furnace 3 and melted, and the molten mixture is then filled into a separate container to slowly cool and solidify. A series of vitrification treatments such as filling with helium gas are carried out. The off-gas G generated in the glass melting furnace 3 when the waste liquid and glass material are introduced is sucked and discharged by an off-gas exhaust pipe 4 and an off-gas suction and exhaust system 5 using a blower or the like. It's getting old. The off-gas discharge pipe 4 is
It has a double tube structure consisting of an outer tube 4a and an inner tube 4b, and an air curtain is formed by feeding compressed air from the compressed air supply system 13 outside the cell 1 via the cell penetration part 14. Ru. In other words, compressed air is jetted into the off-gas discharge pipe 4 from a large number of small holes formed in the inner pipe 4b of the double-walled pipe. By making it smaller,
An air curtain is formed to prevent dust contained in the off-gas from adhering and accumulating on the pipe wall. By the way, as shown in FIG. 3, the ends of the outer pipe 4a and the inner pipe 4b on the suction port 4c side of the off-gas discharge pipe 4 are connected to an introduction part 4d having a convex curved cross section whose diameter gradually decreases in the suction direction. Therefore, it is connected so as to close the annular space. and,
Since the adhesion and accumulation of dust contained in the off-gas G is most severe near the introduction section 4d of the suction port 4c of the off-gas discharge pipe 4, attempts are being made to form an air curtain by providing small holes in the introduction section 4d.

``Problems to be Solved by the Invention'' However, even if a small hole is formed in the introduction part 4d and compressed air is blown out from this small hole, the introduction part 4d, which has a larger diameter than the inner diameter of the inner tube 4b, does not allow off-gas Since the flow velocity of G is not sufficiently large compared to the ejection velocity of compressed air, an air curtain cannot be formed in the introduction section 4d, and dust inevitably accumulates and the introduction section 4d near the suction port 4c is blocked. There was a problem in that the suction and discharge of off-gas was hindered.

This idea was made against the background of the above-mentioned problems, and aims to provide a glass melting furnace that can form a sufficient air curtain even near the suction port of the off-gas discharge pipe and effectively prevent the adhesion and accumulation of dust. It is intended to.

``Means for solving the problem'' This idea involves attaching an off-gas discharge pipe consisting of an outer tube and an inner tube housed within the outer tube to the main body of the glass melting furnace. An air curtain is formed on the inner wall of the inner pipe by blowing the air sent through the slit onto the inner surface of the inner pipe, and the off-gas is isolated from the inner wall and is sucked and discharged from the suction port of the off-gas exhaust pipe. In the glass melting furnace, an introduction part having a vent hole that gradually decreases in diameter in the off-gas suction direction and penetrates in the off-gas suction direction is arranged between the ends of the outer tube and the inner tube on the suction port side. A structure is adopted in which a ring-shaped ring plate communicating with the ventilation hole and opening toward the center with an annular space left therein is removably attached to the upstream surface of the introduction part.

Embodiment FIG. 1 shows an embodiment of the glass melting furnace of this invention, and for ease of understanding, the overall structure of the off-gas discharge pipe will also be explained.

In FIG. 1, reference numeral 20 is a glass melting furnace, and reference numeral 21 is an off-gas discharge pipe. A sleeve 22 into which an off-gas discharge pipe 21 is inserted is attached to the peripheral wall 20a, which is the main body of the glass melting furnace.

The off-gas exhaust pipe 21 has a substantially triple pipe structure, and mainly includes an outer pipe 21a attached to the sleeve 22, an inner pipe 21b housed inside the outer pipe 21a, and an outer pipe 21a and an inner pipe. tube 2
Deflector pipe 2 installed between 1b and
It consists of 1c.

An air purge nozzle 21d for feeding compressed air into the outer tube 21a is attached to the outer tube 21a. Between the inner circumferential wall of the outer tube 21a and the deflector pipe 21c, there is a flow path A for compressed air sent from the air purge nozzle 21d.
are formed between the deflector pipe 21c and the inner pipe 21b, and are connected to each other by a plurality of connecting plates 21e disposed in the length direction to connect the deflector pipe 21c and the inner pipe 21b to the upstream side (the first A flow path B is formed which communicates on the right side in Figure 1). The connecting plate 2
Cutouts 21e ₁ are provided in 1e to match the pitch of the slits 21b ₂ provided in the inner tube 21b. The inner tube 21b is formed by connecting a large number of short tubes _21b1 made of porous sintered metal by the connecting plate 21e.
The outer periphery of the connecting portion of the short tube 21b ₁ is formed into a tapered shape, and when the short tube 21b ₁ is connected, a slit 21b ₂ is formed at the connecting portion to direct compressed air to the downstream side.

Outer pipe 21a and inner pipe 21b on the side of the suction port 21f
The ends of the annular space are connected to each other on the upstream side of the annular space by an introduction part 24 having a convex curved cross-section and having a vent hole 24a that gradually reduces in diameter in the suction direction of the off-gas G and extends in parallel to the suction direction of the off-gas G. connected in a closed state.

It is desirable that a large number of ventilation holes 24a be provided along the circumferential direction of the introduction section 24 in order to form a uniform air curtain on the convex curved surface of the introduction section 24.

A ring-shaped ring plate 25 is attached to the upstream surface of the introduction part 24 and can be attached and detached by screws 25a with an annular space S open in communication with the ventilation hole 24a and opening toward the center. is attached to.

Off-gas discharge pipe 21 in glass melting furnace 20
When configured as described above, compressed air flows from the air purge nozzle 21d to the upstream side through the flow path A, and then flows through the flow path B to the downstream side, as shown by the arrow. The compressed air flowing through the flow path B is ejected from the slit _21b2 of the inner tube 21b, and
An air curtain is formed on the inner wall of the inner pipe 21b on the downstream side of _1b2 .

On the other hand, a part of the compressed air that has flowed through the flow passage A is ejected from the ventilation hole 24a of the introduction part 24, collides with the ring plate 25, changes its direction toward the center axis of the inner tube 21b, and is transferred from the space S to the center axis of the inner tube 21b. gush. Then,
The ejected compressed air forms an air layer, that is, an air curtain, flowing along the inner surface of the introduction section 24. Therefore, even in the inlet section 24 of the off-gas exhaust pipe 21, where the most amount of dust has conventionally been deposited, the off-gas G can be sucked in while being isolated from the inner surface of the inlet section 24 by forming an air curtain. be able to. Therefore, the adhesion and accumulation of dust can be effectively prevented, the introduction section 24 can be prevented from being blocked, and the off-gas can be suctioned and discharged without any problem. on the other hand,
Dust may adhere to the outer surface of the ring plate 25, but in this case, the ring plate 25 may be replaced.

In the above embodiments, the shape of the introducing portion 24 is described as gradually decreasing in diameter, but it may be formed, for example, by a tapered surface decreasing in diameter in a funnel shape. Furthermore, although in the illustrated example, the outer tube 21a and the inner tube 21b are separate members, the introducing portion 24 may be configured integrally with the inner tube 21b, for example. In addition, in the illustrated example, the distance S between the introduction part 24 and the ring plate 25 gradually increases as it moves toward the central axis. Alternatively, the diameter may be gradually reduced toward the suction direction of the off-gas G so as to extend along the inner surface of the introduction section 24. In this case, introduction part 2
Since the air curtain is formed long in the suction direction on the inner surface of 4, the accumulation of dust can be more effectively prevented.

"Effects of the Invention" As explained above, according to the glass melting furnace of the present invention, a ring plate is attached to the inlet of the off-gas discharge pipe, so that compressed air flows from the vent hole in the inlet to the inner surface of the inlet. can flow along to form an air curtain. Therefore, it is possible to effectively prevent dust from adhering to the inlet near the suction port, where dust has conventionally been most heavily deposited, to prevent clogging, and to suction and discharge the off-gas without any trouble.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention, and is a partial sectional view mainly showing a part of an off-gas discharge pipe in a glass melting furnace. FIG. 2 is a conceptual diagram showing a conventional example of an off-gas processing device. FIG. 3 is a sectional view showing a connection part of a conventional off-gas discharge pipe. 20...Glass melting furnace, 20a...Glass melting furnace main body, 21...Off gas discharge pipe, 21a...Outer tube, 21b...Inner tube, 21f...Suction port, 24...
...Introduction part, 24a...Vent hole, 25...Ring plate, G...Off gas, S...Between.

Claims (1)

[Scope of utility model registration request] An off-gas discharge pipe 21 consisting of an outer pipe 21a and an inner pipe 21b housed inside the outer pipe is attached to the glass melting furnace main body 20a, and the air sent between the outer pipe and the inner pipe is passed through a slit 21b ₂ . An air curtain is formed on the inner wall of the inner pipe by ejecting the gas to the inner surface of the inner pipe via the inlet port 21 of the off-gas discharge pipe, with the off-gas G isolated from the inner wall.
In the gas lamination melting furnace configured to suck and discharge air from f, a vent hole 24a is provided between the ends of the outer tube and the inner tube on the suction port side, the diameter of which gradually decreases in the direction of suction of off-gas, and which penetrates in the direction of suction of off-gas. A ring-shaped ring plate 25 is removably attached to the upstream surface of the introduction part, with an annular gap S communicating with the ventilation hole and opening toward the center. Gasura melting furnace featuring: