JPH0532646B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to organic chlorine compounds (for example, PCBs, dioxins, agricultural chemicals such as insecticides), wastes containing the organic chlorine compounds, or research dealing with these compounds. The present invention relates to a device for heating a compound or waste material using microwave energy to decompose and burn the compound when processing waste material such as equipment, equipment, instruments, etc. generated in experiments and tests.

[Conventional technology]

Conventionally, known methods for treating this type of waste include incineration in a heating furnace equipped with a burner, decomposition by ultraviolet irradiation, and oxidative decomposition using ozone.

[Problem to be solved by the invention]

Among these methods, the method using a heating furnace requires a high temperature of 1200 to 1400℃, and because the high temperature is obtained with a burner, temperature unevenness is likely to occur.
This was accompanied by the problem of generation of harmful secondary products. In other words, localized high temperatures tend to occur, which not only necessitates the use of expensive materials for the construction of the furnace, but also has the drawback that thermal decomposition efficiency is difficult to stabilize.For example, when the material to be treated is PCB, dioxins are In some cases, extremely poisonous substances such as these may be produced, which poses a problem of lack of practicality.

On the other hand, decomposition methods using ultraviolet rays or ozone may produce secondary products, similar to methods using heating furnaces, and ozone may leak and be discharged, causing secondary pollution, and the decomposition efficiency may not be sufficient. However, it lacked practicality. In addition, there was a problem that the device became large and difficult to handle.

Furthermore, since this type of device handles highly toxic substances even in minute amounts, there has been a long-awaited development of a device that can operate stably and has considerably high efficiency.

On the other hand, as environmental problems become more serious, there are cases where organic chlorine compounds are handled in laboratories and laboratories. In this case, organic chlorine compounds adhere to and contaminate experimental equipment and instruments, leading to the risk of secondary contamination from these contaminated equipment and instruments, which greatly hinders testing and research. I was getting used to it. Therefore, there has been a desire for a device that can quickly and easily process these wastes even at the laboratory level.

In view of the above problems and demands, the present inventors have previously proposed an apparatus for decomposing and burning an organic chlorine compound or waste containing the organic chlorine compound using microwaves. (Japanese Patent Publication No. 2-50365) However, even in the above invention, there is a drawback that depending on the shape of the object to be treated, sufficient combustion treatment cannot be performed. For example, in the above-mentioned apparatus using microwaves, the hearth is filled with granular microwave absorbing material, and the microwaves introduced into the furnace are selectively absorbed by the microwave absorbing material forming a packed bed. Inside the furnace,
In particular, the surface of the microwave absorbing material and its vicinity are in a high temperature state, but if the shape of the object to be treated becomes large, the heat from the high temperature microwave absorbing material is not transferred to the large material, resulting in incomplete combustion.

The present invention has been made to improve the above invention, and is capable of decomposing and burning organochlorine compounds in high yield and without temperature unevenness, and eliminates secondary products that cause secondary pollution. The purpose is to economically provide a suitable device that is free from the risk of such occurrence.

[Means to solve the problem]

The treatment apparatus of the present invention is an apparatus for decomposing and burning organic chlorine compounds or waste containing organic chlorine compounds using microwave energy, which includes a receiving tank for the material to be treated and a lower part of the receiving tank. The apparatus is equipped with a crushing device for the received processed material arranged at a location, a transfer device for transferring the crushed processed material, and a combustion device for burning the transferred processed material. , the combustion apparatus includes an incinerator in which at least a part of the hearth is made of a refractory microwave absorbing material, and a secondary combustion furnace in which at least a part of the furnace material and/or the furnace wall is made of a refractory microwave absorbing material. The present invention is characterized in that a microwave generator is connected to each of the incinerator and the secondary combustion furnace via a microwave waveguide.

The above-mentioned crushing devices generally include devices that utilize (1) compression force, (2) impact force, (3) shear force, or (4) friction force, and can perform efficient crushing. Which of these methods to apply, that is, which crushing method to adopt, can be determined appropriately by considering the shape, physical properties (for example, size, ease of crushing), and dimensions of the object to be treated after crushing. can. In other words, (1) the compression type is for coarse crushing or intermediate crushing, (2) the impact type is for intermediate crushing, fine crushing, or ultra-fine crushing, and (3) the shear type is for fine crushing or refining tough materials. (4) The friction type is suitable for ultra-fine crushing, but the impact type and shear type are particularly preferred, and if desired, after performing intermediate crushing with the impact type, fine crushing can be performed with the shear type. This is also extremely effective, and therefore, impact type crushers or twin-shaft shear type crushers are particularly suitable as crushers.

[Effect]

The method of processing waste using microwaves is
This is a well-known technique and typically involves applying microwave energy directly to the waste. In the case of direct action, the microwave energy reached inside the waste, and combustion treatment was possible without sufficiently crushing the waste.

In contrast, in the present invention, microwave energy is once absorbed into a granular microwave absorbing material filled in a hearth, the surface of the absorbing material is heated to a high temperature, and waste is processed using the high temperature state of the surface of the absorbing material. Therefore, the combustion efficiency varies depending on the shape and size of the waste. In the present invention, the waste material to be treated is crushed by a crushing device and burnt in a fine shape, so that the material to be treated can be instantaneously decomposed and burned on or near the surface of the furnace material.

In the present invention, the size of the workpiece to be crushed by the crushing device depends on the size and shape of the treatment device,
The length of at least one of them is preferably 5 cm or less, more preferably 1 cm or less, although this varies depending on the type of the object to be treated.

〔Example〕

The present invention will be explained in detail below.

Example 1 An embodiment of the present invention will be described based on the drawings. Waste containing PCBs (materials to be treated), such as capacitors, are received in a receiving tank 1, crushed by a crusher ₁₁ , and then incinerated by a quantitative feeder 2. It is sent to furnace 3 and incinerated.

Since the crusher 1 ₁ is disposed at a lower position within the receiving tank 1 , the materials to be processed that have been put into the receiving tank 1 are sequentially crushed as they are and transferred to the incinerator 3 . This crusher ₁₁ has a shape, size, and size that can crush the material to be processed and transfer it to the incinerator 3 by the quantitative feeder 2.
Any material can be applied as long as it has a function that can be converted into physical properties.

Note that the crusher may be provided downstream of the processing material receiving tank, and the processing material after the processing may be temporarily stored in the storage tank and then supplied to the incinerator 3 by a quantitative feeder.

However, inside the incinerator 3 is a microwave generator 4.
The high temperature state is maintained by microwaves and incineration is carried out. That is, the incinerator 3 has a stirring mechanism such as stirring blades 6 via the rotary drive device 5 in the lower part.
It has a microwave waveguide ₇₁ in its upper part, and the part where the stirring blade is installed is filled with a granular fire-resistant microwave absorbing material 8, and the combustion air is stirred by an air supply fan 9. Although the combustion air is supplied via a mechanism from a combustion air supply pipe (not shown) provided in the lower part of the furnace, it is also possible to use a structure that also serves as an air supply nozzle as the stirring blade 6.

The microwave introduced into the incinerator 3 is selectively absorbed by the microwave absorber 8 to form a high temperature state, and the PCBs supplied by the quantitative feeder 2 are
It instantly decomposes and burns on the surface of the high-temperature microwave absorber.

In other words, the material to be treated is supplied to the surface of the high-temperature microwave absorbing material 8 which is in an agitated and fluidized state, and is instantly combusted and dispersed over the entire surface of the furnace, and a sufficient oxidizing atmosphere is maintained at high temperature, so that the entire area inside the furnace is Good disassembly,
Combustion is achieved.

The material of the microwave absorbing material 8 may be any material as long as it absorbs microwaves and generates heat, and metals or non-metals, oxides or carbides are generally used.
These can also be used in any combination. Specifically, silicon carbide, titanium oxide, and silicon carbide containing silicon nitride are practical and convenient.

Further, it is generally preferable that the microwave absorbing material 8 has a granular shape (for example, a diameter of 5 to 20 mm).

The heating temperature of the material to be treated in the incinerator 3, that is, the furnace wall temperature (in actual operation, the furnace wall temperature is measured and controlled) is preferably 800 to 1500°C, particularly preferably 1000 to 1400°C. , differs depending on the type and shape of the object to be treated, the type of additives described below, etc. For example, if the object to be treated is an insecticide, a relatively low temperature may be sufficient, but in the case of PCBs, a high temperature of 1000° C. or higher is preferable. Furthermore, when a flux or a combustion promoter is added as the additive, the decomposition and combustion of the material to be treated is promoted, so a relatively low temperature is sufficient.

Therefore, as the fluxing agent, alkali hydroxide,
Basic flux such as alkali carbonate, KHSO ₄ , K ₂ S ₂ O ₇
With acidic fluxes such as KNO ₃ , PbO or Na ₂ CO ₃
A mixture _{of K2CO3} , _a mixture of _Na2CO3 and _KNO3 ,
Various materials can be applied, such as a mixture of Na ₂ CO ₃ and MgO, but among these, Na ₂ CO ₃ , K ₂ CO ₃ , KOH
Basic fluxes such as are preferred, and KOH is preferred from the viewpoint of post-treatment and efficiency. Two or more of these may be used in combination. The amount of these fluxes added is 5 W/W% or more, but from the viewpoint of economy and efficiency, it is preferably used within the range of 5 to 50 W/W%.

On the other hand, the combustion accelerator is preferably oxygen, pulverized coal, and oil, and the amount of the combustion accelerator other than oxygen is within the range of 10 W/W% or more,
From the viewpoint of economy and efficiency, it is preferable to use it within the range of 10 to 100 W/W%. Further, oxygen is generally introduced into the furnace as an oxygen-containing gas having an oxygen content of 25 to 50% (by volume). Methods for supplying oxygen include a cryogenic separation method, an adsorption method, and an oxygen-enriched membrane method, and the oxygen-enriched membrane method is preferred from the viewpoint of cost and operability.

By adding such fluxing agents and combustion accelerators, decomposition and combustion are promoted and highly efficient processing is possible.If a substance containing hydroxyl groups such as KOH is added as a fluxing agent, microwaves can Since it has the property of rapidly responding to hydroxyl groups, it has the effect of significantly improving heating efficiency, such as increasing heating rate.

In addition, when using fluxing agents or combustion accelerators, it is possible to perform pre-treatment such as adhering and absorbing these additives to the object to be treated, which allows for easy and safe handling (organic chlorine compounds, etc.). It was difficult to handle because it was highly toxic even in small amounts).

The material to be treated that has been decomposed and combusted with high efficiency in the incinerator 3 is introduced into the secondary combustion furnace 10, where it is further decomposed and combusted. The secondary combustion furnace 10 has a furnace material and/or a part of the furnace wall made of a fire-resistant microwave absorbing material similar to that of an incinerator, and the microwaves from the microwave generator 4 can be used in the same way. maintained at high temperatures. Note that 7 ₂ is a microwave waveguide.

The temperature inside the secondary combustion furnace 10 is 800 to 1500°C, and the optimum temperature, like the incinerator 3, varies depending on the type of material to be treated, the shape of the furnace (residence time), etc.

In this way, by combining an incinerator (heating furnace) and a secondary combustion furnace, extremely highly efficient and stable processing and operation can be achieved. Note that if only relatively high efficiency is required due to economical reasons, the purpose can be achieved with only the incinerator 3.

The exhaust gas after decomposition and combustion is sent to the exhaust gas cleaning tower 12 by the off-gas fan 11, where it is cleaned by the absorbent in the absorption liquid sprayed from above the tower, and chlorine and hydrogen chloride generated from the material to be treated are removed. be done. It is replenished into the absorption liquid tank 13 and circulated by the absorption liquid pump 14.

A part of the circulating absorption liquid is treated in a waste liquid treatment tank 15, and the gas from which harmful gases have been removed is discharged from a chimney 16.

Example 2 In the treatment of vinyl chloride waste by the incinerator 3 of the apparatus shown in FIG. 1, the processing speed in the incinerator 3 was compared between a case where the vinyl chloride waste was crushed and a case where the vinyl chloride waste was not crushed.

The processing conditions are shown below.

Incinerator size: 50 Microwave absorber: granular silicon carbide Microwave power: 4KW Size of vinyl chloride waste (No treatment): Approximately 6 x 5 x 1 cm.

(With treatment): Approximately 1 x 1 x 1 cm or less.

Processing method for vinyl chloride waste: Crush it with an impact crusher and then crush it with a twin-shaft shear crusher.

The results were as follows.

With crushing treatment: 3 kg/h Without crushing treatment: 1 kg/h The combustion rate of crushed waste was three times higher.

〔Effect of the invention〕

1. In the processing apparatus of the present invention, the object to be processed is crushed in advance, and the object to be processed is decomposed and burned using microwaves as a heating source. Therefore, the object to be processed can be efficiently heated to a high temperature, and the output of the microwave can be easily controlled. from,
Heating is easy to control. Output can be turned on and off quickly and easily, so work can be done quickly and easily during emergencies, starting, and stopping operations. Low exhaust gas volume and fewer components. Therefore, the device can be downsized and provided economically. , Enables uniform heating with no temperature unevenness, allowing optimal and stable operation to continue; There is no problem of generation of substances that cause secondary pollution during decomposition or combustion of the processed material; Pre-heating of the processed material Because it is meant to be crushed,
Waste materials of various shapes, sizes, and physical properties can be efficiently processed. Therefore, it is possible to quickly and easily treat and dispose of laboratory equipment contaminated with organic chlorine compounds even at the laboratory level. Also,
The equipment used when handling organochlorine compounds in tests, research, and experiments is often made of organic resins such as PVC, polyethylene, and Teflon, and the method of the present invention has the advantage that these can also be easily burned and treated. be.

2. Furthermore, since the processing apparatus of the present invention is equipped with a receiving tank for the material to be treated, a crushing device, a transportation device for the crushed material, and a combustion device (a scrubber for processing combustion exhaust gas is provided if necessary), the entire device It has the effect of making it possible to downsize and reduce the installation area, and furthermore, by combining an incinerator that uses microwaves as the combustion device and a secondary combustion furnace that also applies microwaves. Because of its structure, it enables smooth, stable and efficient decomposition and combustion of the material to be treated.
The secondary combustion furnace has the advantage of being able to gasify and entrain, decompose and burn the scattered combustibles.

[Brief explanation of drawings]

The drawings are flow sheets illustrating embodiments of the invention. 1... Receiving tank, 1 ₁ ... Crushing machine, 2... Quantitative feeder, 3... Incinerator, 4... Microwave generator, 5... Rotation drive device, 6... Stirring blade, 7 ₁ ,
7 ₂ ...Microwave waveguide, 8...Microwave absorber, 9...Air supply fan, 10...Secondary combustion furnace,
11...off gas fan, 12...exhaust gas cleaning tower, 13...absorption liquid tank, 14...absorption liquid pump, 15...waste liquid treatment tank, 16...chimney.

Claims (1)

[Scope of Claims] 1. An apparatus for decomposing and burning organic chlorine compounds or waste containing organic chlorine compounds using microwave energy, including a receiving tank for the material to be treated and a lower part of the receiving tank. The apparatus is equipped with a crushing device for the received processed material arranged at a location, a transfer device for transferring the crushed processed material, and a combustion device for burning the transferred processed material. , the combustion apparatus includes an incinerator in which at least a part of the hearth is made of a refractory microwave absorbing material, and a secondary combustion furnace in which at least a part of the furnace material and/or the furnace wall is made of a refractory microwave absorbing material. Along with preparing,
Processing of organic chlorine compounds or waste containing organic chlorine compounds, characterized in that the incinerator and secondary combustion furnace are each connected to a microwave generator via a microwave waveguide. Device. 2. The processing device according to claim 1, wherein the crushing device is an impact crusher and/or a biaxial shear crusher.