JPS62127700A - Method of incinerating and processing flame-retardant radioactive waste - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for incinerating flame-retardant radioactive waste, and more specifically, it relates to a method for incinerating flame-retardant radioactive waste. This invention relates to an incineration treatment method for flame-retardant radioactive waste that significantly reduces the volume of combustible radioactive waste.

[Conventional technology] Flame-retardant radioactive waste such as polyvinyl chloride and rubber generated at reprocessing facilities or nuclear power plants has conventionally been melted during temperature rise, resulting in lumps of incinerated material. generate or
As a result of the incineration being fused to the equipment, inconveniences such as incineration cannot be carried out smoothly, high temperatures are generated during incineration and damage to the incinerator, and soot is generated due to incomplete combustion. . In addition, polyvinyl chloride generates hydrogen chloride gas, chlorine gas, etc., and rubber generates sulfur oxide gas, etc., which can cause damage to the walls of incinerator flues and other areas due to dew point corrosion. However, there was a problem in that it was necessary to install equipment to remove these harmful gases from the perspective of preventing air pollution. In particular, when radioactive waste is incinerated, these waste gas processing facilities generate new radioactive waste, and the reality is that these incinerations are not carried out at all.

Therefore, these radioactive wastes were either stored as they were, or after being cut into appropriate sizes, compressed and canned in drums, leading to an increase in the amount of waste. On the other hand, synthetic high-molecular organic compounds such as polyethylene and polypropylene that do not generate harmful gases are currently incinerated with a limited content in waste.

In this way, when incinerating polyvinyl chloride, it has its own unique properties that are different from other synthetic polymeric organic compounds. It has self-extinguishing properties. If excess oxygen is not added, it will turn into coke at temperatures above 300°C. If the surface turns into coke, it will become a type of heat insulator, resulting in insufficient combustion. Due to the difficulty of incineration, and the increased cost of equipment for waste gas treatment, including the need to use high-grade corrosion-resistant materials, even general waste is rarely incinerated, and even more so when it comes to radioactive waste. It is.

Rubber is often used for work rubber gloves, rubber gloves for clove boxes, etc. at M-stage reprocessing or nuclear power plants, but it contains sulfur, and the incineration process itself uses polyvinyl chloride. It is not as difficult, but it is
As with polyvinyl chloride, waste gas disposal problems arise due to the generation of oxide gases.

As a method for incinerating general wastes such as polyvinyl chloride, rubber, or synthetic polymeric organic compound wastes such as polyethylene and polypropylene, the invention described in, for example, Japanese Patent Laid-Open No. 57-21712 has been proposed.

This invention uses a high-load combustion method that maintains a powerful swirling flame flow around the inner periphery of the combustible material supply port. However, this bulletin does not disclose anything about the incineration of radioactive waste, and it is possible to burn highly viscous 1P materials that are self-combustible, solids, and low-calorific materials that are not self-combustible. Only certain things are stated. Further, in the Examples, it is only disclosed that atactic polypropylene, a 100° C. heated melt in No. 1 in Test 1 of Table 1, is treated as a synthetic high-molecular organic compound.

−〇 ″″′ [Problems to be solved by the invention] The present invention aims to improve the flame retardant properties of polyvinyl chloride, rubber, etc. generated at reprocessing facilities or nuclear power plants, etc., which were previously impossible to incinerate. The purpose of the present invention is to provide a method for incinerating flame-retardant radioactive waste, which allows radioactive waste to be easily incinerated, and which suppresses the amount of secondary waste generated to a very small amount.

[Means for Solving the Problems] In other words, the present invention provides a method to solve the problem by:
The waste gas is incinerated by being supplied to an incinerator that maintains a strong swirling flame flow around the inner periphery of the waste supply port, and the emitted waste gas is cooled by a cooler and then passed through a bag filter or electrostatic precipitator before being processed into a high-performance incinerator. A method for incinerating flame-retardant radioactive waste is characterized in that it is treated with a filter and then treated with an alkaline scrubber.

Hereinafter, the present invention will be explained in detail based on the drawings.

Figure 1 is a 1-block diagram showing the incineration treatment method for flame-retardant radioactive waste of the present invention, and Figure 2 is a vertical cross-section of the waste supply device and incinerator used in the present invention. 3 is a cross-sectional view of the /IA' portion of the incinerator in FIG. 2.

Flame-retardant radioactive waste such as polyvinyl chloride and rubber (hereinafter referred to as
The waste (simply referred to as waste) is first supplied to the waste supply device 1. The waste supply device 1 includes a shredder 11 and a storage tank 12
, a screw feeder 13, a waste feeder 14, etc. The waste thrown into the shredder 11 is shredded into small pieces. The shredding machine 11 is equipped with a screen 15, and only shredded pieces of a certain size, for example, 10 cm square or less, are allowed to fall.
The waste that has been cut off and fallen is stored in the storage tank 12 for 10 minutes, and then supplied to the waste feeder 14 by the scrico feeder 13.

Since waste is divided into small pieces, Nokuriko feeder 13
etc., it is possible to stably supply a fixed amount.

The waste supplied by the screw feeder 13 to the waste supply 514 along with the purge air 17 is transferred to the waste supply port 1.
6 to the incinerator 2. , the second waste 11 feeder 14 is equipped with cooling water 18.1 to prevent waste from melting and clogging.
Since the waste feed port 16 of the waste feeder 14R- is directly connected to the incinerator 21, it is cast with a refractory material.

The incinerator 2 consists of an incinerator 21 and a hot air generating furnace 22,
As shown in FIGS. 2 and 3, the incinerator 21 used in the present invention is supplied with a combustion improver from a combustion improver supply port 23 of a hot air generating furnace 22, and has two air supply ports 24.
Since more air is supplied, a strong swirling flame flow is generated on the inner periphery near the waste supply chamber 16.

Before incineration, the incinerator 21 is connected to the heat f
A combustion improver such as high temperature LPG fuel is blown into the generator 22 as a swirling flow to sufficiently store heat.

As such a combustion furnace 21, for example, Japanese Patent Application Laid-Open No. 57-2
It is described in Publication No. 1712. In this combustion furnace 21, the waste is held in a high-temperature swirling flame stream of 1,200 to 1,400 degrees Celsius, and is instantly and completely combusted without becoming a gas, leaving almost no incinerated ash at the bottom of the incinerator 21. It does not accumulate. Therefore, in the present invention, damage to the incinerator 21 bed due to melting of incineration ash hardly occurs.

The waste gas generated by incineration in the incinerator 2 is cooled to 200° C. or lower in a cooler 3, and then particles are removed in a bag filter or an electric precipitator 4. This bag filter or electrostatic precipitator 4 removes most of the particles containing radionuclides.

The waste gas from which particles have been removed is further subjected to a high-performance filter 5 in which ultrafine particles are also removed. In this high-performance filter 5, particles are thoroughly removed by the bag filter or the electrostatic precipitator 4, so the load is significantly reduced.

Through this two-step particle removal process, 99 radioactive particles were removed.
．． More than 99% removed at the second highest level.

The waste gas after being treated with the high-performance filter 5 contains acidic gases such as chlorine gas, hydrogen chloride gas, and nitrogen oxide gas when the waste is polyvinyl chloride, and mainly sulfur oxidation when the waste is rubber. Since it contains oxidizing gases such as nitrogen oxide gas and nitrogen oxide gas, it is treated with an alkaline scrubber 6, rendered harmless as off-gas, and released outside the staff system. Since the scrubber liquid is an extremely low level radioactive waste liquid, the radioactivity concentration can be checked and discharged from C to the outside of the system.

[Example 1] Hereinafter, the present invention will be explained in detail based on Examples. Note that the numerical values in Table 1 are in weight %.

Block 1 shown in Figure 1 - according to the diagram,
Burning treatment was performed. In addition, as flame-retardant radioactive waste, polyvinyl chloride and rubber (trade name: Diox) having the elemental composition shown in Table 1 were used.

The combustible radioactive waste was stored in a polyethylene bag for collection and was fed as it was to the waste supply device shown in FIG. 2. Here, the waste shredded into about 10 pieces of 10 mm square or larger passed through a storage tank, screw feeder, and waste feeder, and was then introduced into an incinerator (C).

The incinerator has the function of maintaining a strong flame flow around the inner periphery of the waste supply port of the waste supply device as shown in Figures 2 and 3.
It has an incinerator shown in the figure, and the supplied waste is incinerated. The generated waste gas is once cooled to below 200'C with a cooler, dust is removed with a bag filter, then treated with a high-performance filter, and an alkaline scrubber is used to remove hydrogen chloride gas, chlorine gas, or sulfur oxide gas. The acidic gases such as those were removed and released as off-gas to the outside of the thread from the staff.

On the other hand, the alkaline scrubber liquid was appropriately neutralized by discarding it as extremely low-level waste liquid, and after checking the radioactivity concentration, it was discharged to the outside of the thread. Table 2 shows the conditions for the hot air generating furnace, the conditions and conditions inside the furnace, the cooler, and the bag filter during the incineration of polyvinyl chloride and rubber wood diox (trade name).

Table 1 Table 2 *1: Product name Thiox, *2: Combustion efficiency - (CO2/ (CO2+CO))
X 100 (%).

[Effects of the Invention] As described above, according to the present invention, flame-retardant radioactive waste such as polyvinyl chloride and rubber generated at reprocessing facilities, nuclear power plants, etc., which could not be incinerated in the past, can be removed. Grilled IJ
This makes it possible to reduce the amount of waste by approximately 1/100. Additional equipment includes hydrogen chloride gas, chlorine gas,
An alkaline scrubber, which is a device for removing acidic harmful gases such as sulfur oxide gas and nitrogen compound gas, is required, but since the waste gas is treated with a bag filter or electrostatic precipitator and then a high-performance filter, an alkaline scrubber is not suitable. It has almost no radioactivity and is easy to process later.

[Brief explanation of drawings]

Fig. 1 is a block flow diagram showing the incineration treatment method for flame-retardant classified waste of the present invention, Fig. 2 is a vertical cross-sectional view of the waste supply device and incinerator used in the present invention, and Fig. 3 is the It is a cross-sectional view of the AA' part of the incinerator in FIG. 2. 1: Waste supply device, 16: Waste supply port, 2: Incinerator, 21: Incinerator, 3: Cooler, 4: Bag filter or electrostatic precipitator, 5: High performance filter, 6: Alkaline scrubber. Patent Applicant JGC Patent Applicant Nippon Steel Kakoki Co., Ltd. Agent Patent Attorney Tatsuo Ito Agent Patent Attorney Tetsuya Ito-1,<--ra1m-2I Figure 3

Claims (1)

[Claims] 1. After shredding flame-retardant radioactive waste, it is supplied to an incinerator that maintains a strong swirling flame flow around the inner periphery of the waste supply port and incinerated, and the waste gas generated A method for incinerating flame-retardant radioactive waste, which comprises cooling the waste in a cooler, passing it through a bag filter or an electric precipitator, treating it with a high-performance filter, and then treating it with an alkaline scrubber. 2. The incineration method according to claim 1, wherein the flame-retardant radioactive waste is polyvinyl chloride or rubber.