JPH0512262Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The invention relates to a glass melting furnace used, for example, in a radioactive waste vitrification plant, etc.
In particular, the present invention relates to a technique for avoiding the inability to discharge molten glass due to blockage of a downstream nozzle for discharging molten glass.

[Prior Art] Generally, the vitrification plant described above is installed to vitrify waste such as high-level radioactive liquid waste generated in a spent fuel reprocessing facility of a nuclear power plant to improve its ease of handling. In order to vitrify the radioactive waste liquid, the waste liquid is mixed with molten glass in a glass melting furnace, and then filled into a storage container and slowly cooled and solidified.

Conventionally, in the glass melting furnace, as shown in FIG. 3, the waste and glass materials are supplied into a glass melting tank 2 inside a furnace body 1, and these are
The electrode 3 is energized to heat and melt the glass to form a molten glass, and this molten glass is passed through a downstream nozzle 4 provided at the bottom of the furnace body 1 and heated by an induction coil wrapped around the furnace body 1. Nozzle 4
Canister (storage container) 5 set under
Types of discharge and filling are used.
In the case of this furnace, the induction coil 6 is intermittently energized to intermittently heat the downstream nozzle 4, and the glass in the downstream nozzle 4 is repeatedly melted and solidified to open and close the downstream nozzle 4. This controls the discharge of molten glass from the downstream nozzle 4, and fills the canister 5 with a certain amount of molten glass.

[Problems to be solved by the invention] By the way, when the waste is processed using such a glass melting furnace, there is a possibility that the flow nozzle 4 is clogged due to the inflow of brick scraps, etc., and the molten glass is Since the concentration of platinum group elements with high melting points is high and the proportion of glass material is high, the viscosity is high, so even if the induction coil 6 is energized, the glass solidified in the flowing nozzle 4 cannot be melted. First, there was a high possibility that the downstream nozzle 4 would remain blocked. In such a situation, it becomes difficult to repair the downstream nozzle 4, resulting in a prolonged period of outage.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a glass melting furnace that can discharge the molten glass in the glass melting tank to the outside of the furnace even if the downstream nozzle is blocked. purpose.

[Means for Solving the Problems] In order to achieve the above object, the present invention has a glass melting tank inside the furnace body, and is provided at the bottom of the furnace body to direct the molten glass in the glass melting tank to the outside of the furnace body. In a glass melting furnace equipped with a downstream nozzle for discharging, a preliminary tank is formed inside the furnace body to communicate the bottom of the glass melting tank with the outside of the furnace body and into which the molten glass in the glass melting tank enters. It is characterized by the provision of a preliminary flow nozzle that discharges the molten glass in the tank to the outside of the furnace body.

[Operation] Even if the downstream nozzle is blocked by solidified glass, the molten glass in the glass melting tank can be discharged from the preliminary tank to the outside of the furnace body by the preliminary downstream nozzle.

[Embodiment] Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 and 2.

Reference numerals 1 to 6 in these figures are the same components as in FIG. 3, and respectively indicate a furnace body, a glass melting tank, an electrode, a downstream nozzle, a canister, and an induction coil.

The furnace body 1 has a structure in which a plurality of heat insulating layers 1b are provided within a metal casing 1a, and the funnel-shaped glass melting tank 2 is formed within the heat insulating layers 1b.

At the top of the furnace body 1, there is a glass melting tank 2 in which wastes such as the aforementioned high-level radioactive liquid waste and glass materials are stored.
A supply nozzle 11 is provided for supplying the inside.

The electrodes 3 include a main electrode 3a inserted from the outside of the furnace body 1 to be exposed inside the glass melting tank 2, a sub-electrode 3b below this, and a bottom electrode 3c arranged at the bottom of the glass melting tank 2. It consists of three types, and the glass is heated and melted by the Joule heat generated by direct electricity.

A recess 12 reaching the heat insulating layer 1b is formed at the bottom of the furnace body 1 at a location corresponding to the bottom of the glass melting tank 2, and the downflow nozzle 4 is arranged here. This downstream nozzle 4 is fixed to the heat insulating layer 1b with its discharge port facing downward. A molten glass flow passage 13 communicating with a flow nozzle 4 is formed in the bottom electrode 3c and the heat insulating layer 1b of the electrode 3, and the molten glass in the glass melting tank 2 passes through the flow flow passage 13 and the flow nozzle 4. is discharged and filled into the canister 5.

A preliminary tank 14 having a rectangular cross section is provided on one side of the furnace body 1 and communicates the glass melting tank 2 with the outside of the furnace body 1.
is formed. The preliminary tank 14 includes a horizontal tank 14a that extends slightly upward from the side of the bottom of the glass melting tank 2 to the side of the furnace body 1, and a horizontal tank 14a that extends slightly upward from the side of the bottom of the glass melting tank 2, and
Vertical tank 14b extending to the top of the furnace body 1 along the wall surface of
It is made up of.

This preliminary tank 14 includes a glass melting tank 2.
The molten glass enters from the horizontal tank 14a and accumulates at the same level as the glass melting tank 2. A pair of upper and lower electrodes 15 are provided at the lower part of the side wall of the vertical tank 14b to prevent the molten glass in the preliminary tank 14 from solidifying and to maintain the molten state.
These electrodes 15 also serve to assist in melting the glass in the preliminary tanks 14a and 14b by passing current between them and between the bottom electrodes 3c.

At the bottom of the furnace body 1, at a location corresponding to the bottom of the vertical tank 14b of the preliminary tank 14, there is a recess 16 that reaches the heat insulating layer 1b.
is formed, and here a preliminary flow nozzle 17 is formed.
(hereinafter referred to as a spare nozzle) is arranged.
This preliminary nozzle 17 is fixed to the heat insulating layer 1b with its discharge port facing downward. A molten glass flowing down passage 18 communicating with the preliminary nozzle 17 is formed in the heat insulating layer 1b. The molten glass (inside) flows down to the outside of the furnace body 1 and is discharged.

Around the preliminary nozzle 17, there is a downstream nozzle 4.
Similarly, an induction coil 6 is mounted on the exterior, and by energizing this induction coil 6, a spare nozzle 17 is activated.
is heated, and at this time, molten glass is discharged from the preliminary nozzle 17.

Note that the outlet of the preliminary tank 14 to the outside of the furnace body 1,
That is, a pipe (not shown) communicating with an off-gas line that sends the off-gas in the glass melting tank 2 to a predetermined processing step is installed in the opening 19 at the top of the vertical tank 14b.

Next, the operating method and operation of the glass melting furnace configured as described above will be explained.

First, waste such as high-level radioactive liquid waste is supplied into the glass melting tank 2 from the supply nozzle 11 together with a glass material. Electricity is applied to the electrodes 3, 3a, 3c and the electrode 15 to melt and mix the waste and the glass material to form molten glass. At this time, each induction coil 6 is not energized yet, and the downstream nozzle 4 and the preliminary nozzle 17 are not heated.

The molten glass in the glass melting tank 2 enters the preliminary tank 14 as it melts, and the molten glass in both tanks 2 and 14 becomes at the same level.

Next, the induction coil 6 on the downstream nozzle 4 side is intermittently energized to intermittently heat the downstream nozzle 4, and the glass in the downstream nozzle 4 is repeatedly melted and solidified to open the downstream nozzle 4. - Closing and controlling the discharge of molten glass from the downstream nozzle 4. As a result, the canister 5 is filled with a certain amount of molten glass.

When the canister 5 is filled with molten glass by the downstream nozzle 4, the glass that has solidified in the downstream nozzle 4 cannot be melted,
If the downstream nozzle 4 is blocked, the induction coil 6 on the side of the spare nozzle 17 is energized to close the spare nozzle 17.
is heated, and the molten glass in the vertical tank 14b of the preliminary tank 14 flows down from the preliminary nozzle 17. This results in
Most of the molten glass is discharged to the outside except for a portion below the bottom of the vertical tank 14b. Incidentally, when the residual glass is allowed to flow down from the preliminary nozzle 17, a predetermined filling container is set under the preliminary nozzle 17.

As described above, in the glass melting furnace of this example,
Even if the downstream nozzle 4 for filling the canister 5 with molten glass is blocked, the molten glass in the glass melting tank 2 can be discharged to the outside of the furnace by the preliminary nozzle 17 provided on the preliminary tank 14 side.

[Effects of the invention] As explained above, the glass melting furnace of the present invention has a glass melting tank inside the furnace body, and is provided at the bottom of the furnace body to direct the molten glass in the glass melting tank outside the furnace body. In a glass melting furnace equipped with a downstream nozzle for discharging water, a preliminary tank is formed inside the furnace body to communicate the bottom of the glass melting tank with the outside of the furnace body and into which the molten glass in the glass melting tank enters. Since a preliminary flow nozzle is provided to discharge the molten glass in the preliminary tank to the outside of the furnace body, even if the flow nozzle is blocked by solidified glass, the molten glass in the glass melting tank can be removed from the preliminary tank by the preliminary flow nozzle. can be discharged outside the furnace body. Therefore, it is possible to simplify the repair of the downstream nozzle and to prevent the operation from being stopped for a long time.

[Brief explanation of the drawing]

1 and 2 are views showing one embodiment of the present invention, in which FIG. 1 is a cross-sectional view thereof, and FIG. 2 is a cross-sectional view thereof.
A cross-sectional view taken along the line - in the figure, and FIG. 3 is a cross-sectional view of a conventional glass melting furnace. 1... Furnace body, 2... Glass melting tank, 4... Downstream nozzle, 14... Preliminary tank, 17... Preliminary downstream nozzle.

Claims (1)

[Scope of utility model registration request] In addition to having a glass melting tank inside the furnace body,
In a glass melting furnace, the bottom of the glass melting tank and the outside of the furnace body are communicated inside the furnace body, and the bottom of the glass melting tank is connected to the outside of the furnace body. A glass melting furnace is characterized in that a preliminary tank is formed into which the molten glass in the glass melting tank enters, and a preliminary flow nozzle is provided for discharging the molten glass in the preliminary tank to the outside of the furnace body.