JPH03260512A - Incinerator and method of igniting radioactive waste material - Google Patents

Abstract

PURPOSE:To provide a superior igniting characteristic capable of increasing a mixed combustion ratio with substances hardly ignited and reduce a capacity of an incinerator and a discharged gas processing facility by a method wherein a main body of an incinerator for igniting waste material is provided with an oxygen rich air supplying facility for supplying air having a specified oxygen concentration as combustion air and remained combustion air and with a steam injection facility for injecting or atomizing water against a combustion part. CONSTITUTION:In this type of incinerator, air having an oxygen concentration of 25 to 40% is supplied as combustion air to a main body 1 of an incinerator by a rich oxygen supplying facility 2. Combustion speed of decomposed gas and soot in their gaseous phases generated when an easy-to-burn substance and a hard-to-burn substance in the radioactive waste material are ignited together is increased in proportion to oxygen concentration and then an igniting characteristic can be improved. In addition, it is possible to decrease the amount of waste gas. Water is atomized by a steam injection facility 5 against an igniting part, thereby a reduction in concentration of waste gas and adhesion of ignited and melted substance against the wall of an incinerator are prevented. Average supplying amount may be set at about 1/10 of the amount of combustion air. In this way, the combustion is carried out while a temperature of waste gas is being controlled to a value less than 1,000 deg.C.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention provides an incinerator suitable for incinerating combustible miscellaneous solid waste generated from nuclear facilities, and a method for incinerating radioactive waste using the incinerator. It is related to.

(Prior technology) Combustible miscellaneous solid waste generated from nuclear facilities such as nuclear power plants has traditionally been incinerated in incinerators, but in this case, combustible materials such as polyethylene, paper, cloth, etc. In addition to exclusive combustion, mixed combustion with flame retardants such as rubber, waste resin, and sludge is also carried out. However, co-firing with such flame retardants generates unburnt materials, soot, etc., which increases the burden on exhaust gas treatment equipment in subsequent processes, so the co-firing ratio has been kept low. In addition, such conventional incinerators require large-scale exhaust gas treatment equipment including filters, blowers, etc., resulting in high equipment costs and high maintenance costs.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems, has excellent combustibility that can increase the co-combustion ratio with flame retardants, and This was completed in order to provide an incinerator that can reduce equipment capacity and a method of incinerating radioactive waste using the incinerator.

(Means for solving the problem) The above problem is that the furnace body for incinerating waste has a
This problem is solved by an incinerator characterized by being equipped with oxygen-enriched supply equipment that supplies air with an oxygen concentration of ~40% as combustion air and flammable air, and steam injection equipment that sprays water into the combustion section.

In addition, the above problem was solved by putting radioactive waste into an incinerator with the above structure and spraying water to reduce the exhaust gas temperature to 1,000 yen.
The problem is solved by a method of incinerating radioactive waste, which is characterized by burning while controlling the temperature below ℃.

(Example) The present invention will be explained in more detail below with reference to the drawings.

In the figure, (1) is the furnace body for incinerating waste such as radioactive waste, and air with an oxygen concentration of 25 to 40% is supplied to this furnace body (1) as combustion air and flammable air. An oxygen-enriched supply facility (2) is attached.

As the oxygen-enriched supply equipment (2), for example, an oxygen-enriched membrane can be used, and the oxygen-enriched membrane is supplied to the combustion section of the furnace body (1) via the combustion air supply path (3) and the flammable air supply path (4). Supplying oxygen air. By supplying air with a high oxygen concentration in this way, combustibility improves and it becomes possible to increase the co-combustion ratio with flame retardants, but if the oxygen concentration is less than 25%, ordinary air is used. The difference in combustibility from that of a normal incinerator is insufficient, and on the other hand, if the oxygen concentration exceeds 40%, the combustion temperature will become too high, so air with an oxygen concentration of 25 to 40% is appropriate.

(5) is a steam injection equipment that can spray water into the combustion part of the furnace body (1). This steam injection equipment sprays water at an amount of about 115 to 20 l/20 of the amount of combustion air from a nozzle installed in the furnace.The latent heat of vaporization of the sprayed water lowers the temperature of the combustion section, reducing the amount of spray. Adjustment reduces exhaust gas temperature to 1ooo''C
Control to maintain the following. Here, the exhaust gas temperature is 1
The reason for setting the temperature below 000℃ is that at higher temperatures, cracks and cracks will occur more frequently due to expansion and contraction of the refractory bricks.
This is because the lifespan is shortened and the influence on the temperature measuring device, control equipment, etc. inside the furnace is increased.

(6) is exhaust gas treatment equipment including a filter (7) and an exhaust gas blower (8). The combustion gas in the furnace is filtered through a filter (7
) to completely remove radioactive substances, etc., and then discharged to the outside of the thread by an exhaust gas blower (8).

(Function) In the incinerator of the present invention having the tank bottom as described above, air having an oxygen concentration of 25 to 40% is supplied as combustion air to the furnace body (1) by the oxygen-enriched supply equipment (2).

Among radioactive wastes, combustion of decomposed gas and soot in the gas phase occurs when co-combustion of combustible materials such as polyethylene, paper, and cloth with flame retardant materials such as rubber, waste resin, and sludge. The speed increases in proportion to the oxygen concentration, improving combustibility, so even if co-fired with flame retardants, it can be quickly combusted without producing a large amount of unburned materials or soot. Therefore, it is possible to reduce the amount of exhaust gas. Please note that the oxygen index (an indicator of flammability that indicates oxygen concentration) of rubber, etc. is 3.
0 to 40, so the higher the oxygen concentration in the oxygen-enriched air, the better in order to improve combustibility and reduce the amount of exhaust gas, but as mentioned above, if the oxygen concentration is too high, the temperature inside the furnace and the exhaust gas temperature will rise excessively. A range of 25 to 40% is preferable since this causes an increase in the amount of water.

Furthermore, in the incinerator of the present invention, water is sprayed into the combustion section by the steam injection equipment (5), thereby reducing the exhaust gas temperature and preventing molten incineration material from adhering to the furnace wall. The supply amount is approximately 115 of the amount of combustion air in the case of combustion of a high calorific value such as polyethylene, and the amount of combustion air when the rise in exhaust gas temperature is small due to the combustion of a low calorific value such as a water-containing material. It should be about l/20 of
On average, it should be around 1710. In this way, combustion is performed while controlling the exhaust gas temperature to 1000''C or less, and the exhaust gas is purified by the exhaust gas treatment installation (6) and then released to the outside of the system.

In order to confirm the effects of the present invention described above, an incineration test using the method of the present invention in which oxygen-enriched air is supplied using an oxygen-enriched membrane, and an incineration test using a conventional method using normal air were conducted.

The test equipment is a miscellaneous solid waste incinerator with a rated processing capacity of 10 kg, and the test samples are polyethylene, rags, and wet rags (which are simulated combustible miscellaneous solid wastes commonly generated at nuclear power plants). 50% water) to 15:1:4
A mixture of 200 g of each bag was used. And the flow rate of combustion air is such that the oxygen concentration is 27
% oxygen-rich air, 14ON%/h, and normal air with an oxygen concentration of 21%, 18ON rrr/h.The incineration time was 3 hours in both cases, and the temperature at the bottom of the furnace at the start of incineration was approximately The exhaust gas temperature measured at the 900°C primary ceramic filter was 700-750°C. Also, 1710 water of combustion air was sprayed into the combustion section by installing a steam injector (5).

As a result, according to the method of the present invention, the load on exhaust gas treatment stage # (6) was reduced to 70% of the conventional method. In addition, according to the method of the present invention, the amount of incineration residue is 33g, which is significantly reduced compared to 59g in the case of the conventional method, and the residual salt removal time is 18g compared to the conventional method.
This is a significant decrease of 8 minutes compared to the previous 8 minutes. Furthermore, according to the method of the present invention, the dust concentration in the exhaust gas at the furnace outlet is 0.00 compared to the conventional 0.02 to 0.1 g/N+d.
It was found that the combustibility was significantly improved by an order of magnitude lower than 4 to 0.02 g/Nrrr.

(Effect of the invention) The effects of the present invention are summarized as follows.

(2) The present invention can improve the combustion rate of cracked gas and soot by adopting an oxygen-enriched combustion method, and can reduce soot and the like and improve combustibility. For example, increase the oxygen concentration to 27%
By doing so, the amount of soot generated can be reduced to 1/10.

(2) According to the present invention, it is possible to easily incinerate even flame retardant materials such as water-containing materials and materials with low calorific value, and the co-combustion ratio of these materials can be increased.

(2) According to the present invention, the amount of exhaust gas can be reduced by adopting the oxygen-enriched combustion method, so the capacity of the incinerator and exhaust gas treatment equipment can be reduced. in particular,
When the oxygen concentration is 30% and low heat generation ornaments are exclusively fired, the furnace capacity can be 50% and the capacity of the exhaust gas treatment equipment can be 70%. In addition, when the oxygen concentration is the same and high heat generation figurines are exclusively fired (under severe conditions of excessive temperature rise), the furnace capacity can be increased to 74% by setting the water supply amount to 175% of the combustion air.
%, and the capacity of the exhaust gas treatment equipment can be made 85%.

■According to the present invention, by supplying water from the steam injector equipment, the influence of excessive rise in exhaust gas temperature on the refractory bricks on the furnace wall (shortening of life) and the sticking of incinerated materials to the furnace wall due to melting can be prevented. It can be prevented. Therefore, the present invention greatly contributes to the development of industry as an incinerator that solves the problems of the conventional incinerator and a method of incinerating radioactive waste using the incinerator.

[Brief explanation of drawings]

The drawings are schematic cross-sectional views showing embodiments of the invention. (1): Furnace body, (2): Oxygen-enriched supply equipment, (5): Steam injection equipment. 1: Great prayer 2 bread wheels 1 cane Kawanishi 5: Snar doctor injishifu power 1 wise man lees

Claims (1)

[Claims] 1. The furnace body (1) for incinerating waste has 25 to 4
An incinerator characterized by being equipped with oxygen-enriched supply equipment (2) that supplies air with an oxygen concentration of 0% as combustion air and residual combustion air, and steam injection equipment (5) that sprays water into the combustion section. . 2. A method for incinerating radioactive waste, comprising charging the radioactive waste into the incinerator according to claim 1, and burning the waste while controlling the exhaust gas temperature to 1000° C. or less by spraying water.