JP6596208B2 - Method and apparatus for producing waste oil solidified body - Google Patents

Description

  The present invention relates to a processing technique for incinerating waste oil such as turbine oil, lubricating oil, EHC oil, etc., from radioactive waste discharged from a nuclear power plant, and molding the waste oil into a solidified body.

Nuclear power plants use a variety of oils. Examples include lubricating oil for rotating equipment such as turbine oil and pumps, EHC oil, and the like. These oils become liquid radioactive waste after use, and are filled in drums and stored in the plant before disposal.
As a method of treating waste oil, the present situation is that it is absorbed by paper immediately before incineration and put into an incinerator together with combustible waste for incineration. Oils are generally incinerated, but because they are liquid, there is a risk of leakage when they are put into an incinerator, and waste oil discharged from nuclear power plants is handled as radioactive waste. There is a problem that the radioactive contamination area expands. In addition, because it is absorbed by paper, incomplete combustion may occur and soot may be generated, which may increase the differential pressure of the filter at the rear stage of the incinerator, and in the case of EHC oil Is currently stored in the plant without disposal, due to the possibility that phosphorus compounds may scatter and increase the differential pressure of the filter at the rear of the incinerator. The volume is steadily increasing. In addition, there is no saying that organic matter can be easily decomposed by using supercritical technology, but it is practical because it is expensive and the maintenance is not easy to handle radioactive materials. There has been no case.

  In addition, as a method for treating EHC oil, a method of mixing and hydrolyzing with an aqueous sodium hydroxide solution to form a phosphoric acid compound, and then incineration disposal has been proposed (Non-patent Document 1). Since an aqueous sodium oxide solution is a hazardous material, it is not easy to handle, and an operation such as a filter press is required to take out a phosphate compound from such an aqueous solution. However, it is difficult to handle dangerous materials and radioactive materials, and they have not been put to practical use.

  On the other hand, the present applicant proposes a method for producing an aggregate solidified body by mixing a combustible binder and a waste ion exchange resin, or further blending by adding a calcium salt as a method for easily treating the waste ion exchange resin. (Patent Documents 1 and 2). In this manufacturing method, the moisture of the waste ion exchange resin is roughly cut, and a combustible binder such as petroleum wax is mixed therewith and then heat-molded by a kneading machine. However, the object dealt with in these patents is a waste ion exchange resin, which relates to a method of solidifying a flame-retardant solid with a wax and incineration disposal, and is not intended for a liquid.

JP 2005-31060 JP 2007-136274 A

“Development of Combustion Treatment Method for Control Oil (EHC Oil) Waste Oil” Chubu Electric Power Co., Ltd. Technology Development News No.148 / 2013-7

The objective of this invention is providing the manufacturing method and manufacturing apparatus of a radioactive waste oil aggregate solidified body which enable efficient and stable incineration processing at low cost. More specifically, a method and an apparatus that can stir waste oil and a combustible binder and stably produce an aggregated solid body are provided. The “aggregated solidified body” means all solidified aggregates formed by combining waste oil with a combustible binder as a binder.

  In order to solve the above-mentioned problems, the present inventors have intensively studied. As a result, the waste oil and the combustible binder are melt-mixed by heating and mixing, and then the waste oil and the combustible binder are not separated by cooling. It was found that it can be solidified. Specifically, waste oil is mixed with a combustible binder having a relatively low melting point such as petroleum wax or vegetable wax and solid at room temperature, and stirred while heating to obtain a desired shape such as spherical, cylindrical, prismatic, etc. Knowing that it is possible to stably produce a solidified body of waste oil that can be easily loaded into an existing incinerator and incinerated without generating soot due to incomplete combustion, The present invention has been completed.

  In addition, when the waste oil contains elements such as ions and phosphorus, the waste oil can be mixed with an inorganic compound containing calcium without causing the generation of SOX (sulfur oxide) or an increase in the filter differential pressure due to the phosphorus compound. It was found that the solidified body could be incinerated, and the present invention was completed.

  Examples of the waste oil that can be treated in the present invention include waste oil generated in a nuclear power generation facility.

  The waste oil that can be treated in the present invention is not particularly limited as long as it is waste oil discharged from a nuclear power plant, except for low-boiling substances such as methanol, turbine oil, lubricating oil, EHC oil, heavy oil. Preferable examples include diesel oil and gasoline.

  The combustible binder that can be used in the present invention is preferably a substance that has a softening point below the boiling point of water and is solid at room temperature, and preferably includes petroleum wax, vegetable wax, wood wax, white wax, and the like. Can do. As the petroleum wax, a paraffin wax having a softening temperature range of 45 to 55 ° C., for example, 125P, 130P, 135P, 140P, 145P, 150P, 155P, etc. defined in JISK2235 can be preferably used. In the present invention, when the combustible binder is thermoformed, the combustible binder is preferably used in a softened state at a temperature that does not reach the melting point. Exceeding the melting point is not preferable because a liquefaction phenomenon of the combustible binder occurs and the yield is extremely reduced. When the combustible binder is used in powder or granular form, 155P (granular, granular, powdery) or 140P (granular) is preferred. Note that the “melting point” of paraffin wax is the temperature at which the temperature drop rate of the sample falls below a prescribed rate when the molten sample is allowed to cool under predetermined conditions (JISK2235).

  The content of the combustible binder is preferably in the range of 33 to 200 parts by mass and more preferably in the range of 50 to 150 parts by mass with respect to 100 parts by mass of the waste oil. Within this range, the mixture of waste oil and combustible binder can maintain a stable shape, and in addition, the amount of combustible binder used can be reduced, so from an economic point of view. It is advantageous.

  Preferred inorganic compounds containing calcium that can be used in the present invention include calcium salts excluding carbonates such as calcium nitrate, calcium hydroxide, calcium acetate, and calcium oxide. Since the calcium salt reacts with phosphate ions in the waste EHC oil and precipitates as calcium phosphate, the discharge of phosphorus into the liquid is suppressed.

The amount of calcium salt that can be used in the present invention is preferably 33 parts by mass or more and 100 parts by mass or less, more preferably 50 parts by mass or more and 7 parts by mass or less with respect to 100 parts by mass of waste oil.
5 parts by mass or less. Use of a large amount of calcium salt contributes to improvement of combustion efficiency and reduction of combustion residues, but is not preferable because the operating cost of incineration treatment of waste oil becomes high.

  Therefore, according to this invention, the aggregate solidified body of the waste oil containing waste oil, a combustible binder, and the calcium salt depending on the case is provided. The shape and size of the aggregate and solidified body of waste oil according to the present invention are not particularly limited, but it is preferably a shape and size that can be incinerated with ordinary incineration facilities owned by a nuclear power plant or the like. An incineration process is possible if it is a size that passes through the inlet of the incinerator, but 20 kg or less is preferable in consideration of transportation by humans. Furthermore, it is preferable that the aggregated solidified body of waste oil of the present invention has such strength that it can be incinerated with an incineration facility owned by a general nuclear power plant. The aggregated solid body preferably has a strength that does not pulverize most when it is put into an incineration facility, a strength that can withstand a load during loading, and an impact using a heavy machine during transportation.

  Moreover, according to this invention, the manufacturing apparatus which enforces the manufacturing method of the aggregate solidification body of the waste oil of this invention is provided. The waste oil aggregate solidified body production apparatus of the present invention comprises a waste oil storage tank, and a combustible binder selected from petroleum wax, vegetable wax, wood wax, and white wax having a softening point below the boiling point of water and solid at room temperature , A storage tank for an inorganic compound containing calcium, a waste oil from the storage tank for the waste oil, a flammable binder from the storage tank for the flammable binder, and a measuring mechanism for measuring the inorganic compound from the storage tank for the inorganic compound And a mixing tank for receiving and mixing waste oil, combustible binder, water absorbing material and inorganic compound respectively measured by the measuring mechanism, and heating means, and forming the mixture into a desired shape while heating and kneading the mixture. And a cooling means for cooling the molded body.

  The aggregated solid obtained by this method has been confirmed by visual confirmation that the waste oil and the combustible binder are uniformly mixed, have no large cracks or shrinkage cavities, and do not pulverize even when thrown into an existing incinerator. Therefore, it is possible to incinerate sufficiently.

  In addition, since the aggregated solid body after blending with the combustible binder can be formed simply by cooling, it is very simple.

FIG. 1 is a schematic flow diagram showing the steps of a production method using a production apparatus for a waste oil aggregate solidified body of the present invention. FIG. 2 is an external view photograph of the waste oil solidified body.

Preferred embodiment

  As an embodiment of the method, waste oil discharged from a nuclear power generation facility will be described as an example with reference to the drawings.

  FIG. 1 is a schematic flow diagram showing the steps of a production method using the oil-solidified production apparatus of the present invention.

A powder or granular combustible binder selected from petroleum wax, vegetable wax, wood wax, and white wax having a softening point below the boiling point of water and solid at room temperature to waste oil discharged from a nuclear power plant, A combustible binder addition step (5) for adding and mixing at a ratio in a range of 33 parts by mass to 200 parts by mass with respect to 100 parts by mass of waste oil, and supplying the mixture to a stirring and mixing tank to thereby produce waste oil and the combustible A kneading and molding step (6) for kneading the combustible binder while maintaining the temperature above the softening point of the combustible binder and not reaching the melting point to form a molded body of a desired shape, and cooling the molded body And cooling and solidifying step (7) for solidifying.

  Further, when the waste oil contains phosphorus element, an inorganic compound containing calcium is added to the mixture of the waste oil and the combustible binder in a range of 33 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the waste oil. It is preferable to further include a calcium salt addition step (5).

  Further, as shown in FIG. 1, the manufacturing apparatus of the present invention includes a waste oil storage tank 10, a combustible binder storage tank 20, a quantitative supply mechanism 40 that supplies waste oil from the waste oil storage tank 10, and a combustible binder storage tank 20. A metering mechanism 50 for metering the combustible binder, and a stirring and mixing tank 60 that includes heating means, receives the waste oil supplied by the metering supply mechanism 40, and the combustible binder metered by the metering mechanism 50 and mixes them. And a molding device 70 for molding the mixture, and a cooling means for cooling the molded body. As shown in FIG. 1, it is preferable to further include an inorganic compound storage tank 30 and a metering mechanism 50 that measures the inorganic compound from the inorganic compound storage tank 30 and supplies it to the stirring and mixing tank 60. It is preferable that the manufacturing apparatus of the present invention further includes a solidified body storage tank 80 for storing the aggregate solidified body formed by the forming apparatus 70, and the solidified body storage tank 80 also functions as a cooling means. Further, the solidified body storage tank 80 may be provided with a charging means for charging the aggregated solidified body into an incinerator (not shown). In addition, the fixed supply of the waste oil from the waste oil storage tank 10 to the stirring and mixing tank 60 can be transferred by a pump or the like while monitoring the supply amount by the liquid level of the stirring and mixing tank 60 or the transfer flow rate.

  EXAMPLES Hereinafter, although this invention is demonstrated referring an Example, this invention is not limited to these.

  Using the production apparatus shown in FIG. 1, waste oil is measured by the quantitative supply mechanism 40 and supplied to the mixing and stirring tank 60, and then combustible binder (petroleum wax: granular wax manufactured by Nippon Wax Co., Ltd.). : PF-155; suitable softening temperature range 45 to 55 ° C.) is measured by the measuring mechanism 50 and added to the stirring and mixing tank 60, and the two are mixed, kneaded and molded while heating with a stirrer Was formed, discharged from the bottom of the stirring and mixing tank 60, received by the molding machine 70, molded, and then cooled to produce the waste oil aggregate solidified body of the present invention. In this example, 1 part by weight of wax was mixed with 1 part by weight of waste oil. The appearance of the solidified body is shown in FIG. A robust solidified body could be produced. Moreover, when it incinerated using the 700 degreeC electric furnace, it confirmed that it could incinerate completely.

  1, the waste EHC oil is weighed by the quantitative supply mechanism 40 and supplied to the stirring and mixing tank 60, and then combustible binder (petroleum wax: granule manufactured by Nippon Wax Co., Ltd.). Wax: PF-155; suitable softening temperature range 45-55 ° C.) and slaked lime are weighed by the measuring mechanism 50 and added to the stirring and mixing tank 60, and the mixed fluid of waste oil and wax is heated in the stirring and mixing tank 60 , Discharged from the bottom of the stirring and mixing tank 60, received by the molding machine 70, molded, and then cooled, to produce the waste oil aggregate solidified body of the present invention. In this embodiment, 1 part by weight of waste oil is mixed with 1 part by weight of wax and 0.5 part by weight of slaked lime. As in Example 1, a solidified product could be produced. Moreover, when it incinerated using the 700 degreeC electric furnace, it was able to incinerate completely and it confirmed that the residue was a calcium phosphate.

  According to the present invention, an aggregate solidified body in which waste oil is in a form that can be incinerated with existing incineration equipment is manufactured.

The solidified aggregate produced according to the present invention solves the problems of the conventionally proposed methods for treating waste oil, and enables efficient and stable incineration at low cost.

  In particular, in the case of waste oil containing phosphorus such as waste EHC oil, by adding a calcium salt, it is possible to stably produce an aggregated solid and to suppress the scattering of phosphate compounds generated during incineration. The problem of increasing the differential pressure of the incinerator filter can be solved. In the method described in Non-Patent Document 1, it is necessary to add sodium hydroxide. However, in this method, it is not necessary to add sodium hydroxide because it is heated at a high temperature in an incinerator. Can also be reduced.

  In addition, according to the present invention, in nuclear power generation facilities and the like, waste oil as radioactive waste that has been stored in a large amount as a liquid and is expected to increase in the future because there is no appropriate treatment method so far is combustible. By forming into a solidified body together with a binder, it can be stored for a long time before incineration, and can be easily incinerated using existing incineration facilities owned by each nuclear power generation facility. Therefore, waste oil stored in large quantities can be easily and efficiently incinerated with conventional miscellaneous solids at low cost without capital investment such as improvement of new processing facilities or existing processing facilities. Incineration is possible.

Claims (4)

100 parts by mass of waste oil discharged from a nuclear power plant with a powder or granular combustible binder selected from petroleum wax, wood wax and white wax having a softening point below the boiling point of water and solid at room temperature A combustible binder addition step of adding and mixing at a ratio in the range of 33 parts by mass to 200 parts by mass,
While supplying these mixtures to a stirring and mixing tank and maintaining the temperature not lower than the melting point above the softening point of the combustible binder , the waste oil and the combustible binder are kneaded to form a desired shape. A kneading and forming step for forming into a body;
A cooling and solidifying step of cooling and solidifying the molded body;
The manufacturing method of the aggregate solidified body of waste oil characterized by including this.   The waste oil contains a phosphorus element, and a calcium salt in which an inorganic compound containing calcium is added to a mixture of the waste oil and the combustible binder in a range of 33 parts by mass to 100 parts by mass with respect to 100 parts by mass of the waste oil. The method for producing a solidified body of waste oil according to claim 1, further comprising an adding step. A tank of waste oil discharged from the nuclear power plant,
A flammable binder reservoir selected from petroleum wax, wood wax, and white wax having a softening point below the boiling point of water and solid at room temperature;
A waste oil metering mechanism for measuring and supplying waste oil from the waste oil storage tank, and a combustible binder measurement mechanism for measuring the combustible binder from the combustible binder storage tank;
A mixing tank for receiving and mixing the waste oil and the combustible binder measured by the waste oil quantitative supply mechanism and the combustible binder measuring mechanism, respectively;
A molding apparatus comprising a heating means, receiving a mixture from the mixing tank, and molding the molded body into a desired shape while heating and kneading to a temperature not exceeding the softening point of the combustible binder and reaching the melting point ;
Cooling means for cooling the molded body;
An apparatus for producing a solidified body of waste oil, comprising: The waste oil contains phosphorus element,
A reservoir of inorganic compounds containing calcium;
An inorganic compound measuring mechanism for measuring an inorganic compound from the inorganic compound storage tank;
The said mixing tank receives the inorganic compound measured by the said inorganic compound measuring mechanism in addition to the said waste oil and a combustible binder, The manufacturing apparatus of the aggregate solidified body of the waste oil of Claim 3.