JPH02145259A - Cleaning method for power generating turbine of boiling water nuclear power generation equipment - Google Patents

Abstract

PURPOSE:To sufficiently remove attachments from the surface of a turbine and to eliminate the wear of the turbine surface by blowing a powder body consisting of a thermosetting resin to the surface of a power generating turbine together with a gaseous body current and removing the attachment from this surface. CONSTITUTION:A powder body 10 consisting of a thermosetting resin is blown from a nozzle 24 together with a gaseous body current (compressed air) to the surface of the power generating turbine of a boiling water nuclear power generating equipment and the attachment is removed from the surface of the turbine. In this case, a melamine resin is taken for the thermosetting resin and the grain size of this powder body is taken in 20 - 120 mesh.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for cleaning a power generation turbine of a boiling water nuclear power generation facility by a blasting method.

Prior Art In nuclear power plants, the thermal energy produced by nuclear fission is extracted from the core by primary cooling water and converted to electrical energy in a steam plant. In boiling water nuclear power generation facilities, secondary cooling water is boiled by the heat received from the fuel as it ascends the core, and after being separated into steam and water by a steam separator installed above the core, the steam is directly It is sent through steam pipes to power generation turbines. As a result, dirt adheres to the power generation turbine, and it is necessary to clean the turbine once every one to two years to remove the adhered substances. Conventionally, this cleaning has been accomplished by a dry blasting method in which sintered alumina is used as an abrasive and the abrasive is blown onto the surface of the turbine with a stream of air. The amount of abrasive used for one turbine cleaning reaches 3 to 6 tons.

Problems to be Solved by the Invention When sintered alumina is used as an abrasive, there is a problem in that the turbine surface is easily abraded.

Furthermore, the abrasives used for cleaning cannot be taken out of the controlled area and must be packed in concrete and stored, resulting in the problem of requiring a large storage area.

It is an object of the present invention to provide a novel method for removing deposits on a turbine surface which solves the above-mentioned problems with the conventionally used blasting methods.

An object of the present invention is to provide a method for removing deposits from a power generation turbine of a boiling water nuclear power generation facility without abrading the surface of the turbine.

Another object of the present invention is to provide a method for removing adhered substances using powder that can be post-treated after being used for removing adhered substances.

Means for Solving the Problems The present invention is a blasting method that solves the above problems,
This method involves spraying powder made of a thermosetting resin onto the surface of a power generation turbine of a boiling water nuclear power generation facility together with a gas flow to remove deposits from the surface of the turbine.

The thermosetting resin used in the present invention may have a single composition or a mixture of a plurality of compositions, but is particularly preferably composed of a melamine resin. In addition, the particle size of the powder made of thermosetting resin is not particularly limited, but is defined in JIS R-6001-1973.
Preferably, it is between 20 and 120 mesh. The particle shape of the powder may be any shape. The hardness of the powder particles is not particularly limited, but is 3 on the Mohs hardness scale.
It is preferably from 4 to 4. The powder can be obtained by pulverizing lumps, pellets, etc. of a cured thermosetting resin using a pulverizer.

Although various blasting methods can be used to spray the powder together with a gas flow, a dry blasting method is most suitable. The dry blasting method includes (a) a gravity blasting method in which the powder is put into a tank located higher than the nozzle, and the powder falls to the outlet provided at the bottom of the tank due to gravity and is injected from the nozzle together with compressed gas; (b) A direct pressure blasting method in which powder is sealed in a powder pumping tank, compressed gas is sent into the tank, and the powder is discharged from a discharge port provided at the bottom of the tank and is injected from a nozzle together with the compressed gas. c) A siphon blasting method in which the powder is put into a tank located at a lower position than the nozzle, and the powder discharged from the outlet provided at the bottom of the tank is injected from the nozzle along with the compressed gas using a compressed gas cylinder. However, any of these blasting methods can be used.

Compressed air is usually used as the compressed gas. Usually, the pressure is between 3 and 10 kg/c+*' gauge, and the injection speed of the compressed gas from the nozzle is between 50 and 240 m/sec. Further, the amount of powder used for cleaning, the pressure of compressed gas, and the injection speed can be appropriately selected depending on the characteristics of the powder used and the state of adhesion of adhesion substances to the turbine.

Adhesive substances are present in the powder after being used to remove the adhering substances, and the powder and the adhering substances form a non-uniform mixture. When this mixture is incinerated in a combustion furnace, the residue after combustion of the thermosetting resin and the attached substances remain as incineration residue. The exhaust gas discharged from the combustion furnace is discharged into the atmosphere through appropriate exhaust gas treatment equipment such as a filter. The residue after combustion of the thermosetting resin powder is at most several percent of the amount of the pine resin powder before combustion. Although various types of combustion furnaces can be used, electric furnaces are preferred. Incineration residues containing adhering substances can be disposed of by appropriate disposal methods such as concrete filling.

When powder made of thermoplastic resin is used, if the powder used for cleaning is incinerated in a combustion furnace, the thermoplastic resin will melt in the combustion furnace and stick to the bottom of the combustion furnace, resulting in combustion of the incineration residue. Subsequent processing becomes extremely difficult. Therefore, it is essential to use powder made of thermosetting resin.

Hereinafter, the present invention will be specifically described by way of examples with reference to the drawings.

Adhesive substances precipitated and attached to the surface of a power generation turbine of a boiling water type nuclear power generation facility were removed using a powder made of melamine resin with a particle size of 42 to 90 mesh. A direct pressure blasting device 20 was used for the removal. The powder 10 was put into a tank 22, and compressed air was fed into the tank 22 and the conveying pipe 26 from a compressed air source. The amount of compressed air fed from the compressed air source was 1Nm''/min, and the pressure was 5 kg/cm'' gauge pressure. Reduce the amount of powder used to 300
kg/hour. The powder discharged from an outlet provided at the bottom of the tank 22 is conveyed through a conveying pipe by compressed air and is injected through a nozzle 24.

The inner diameter of the nozzle was 511111, the injection speed of compressed air from the nozzle was 150 m/sec, and the distance from the nozzle to the surface of the turbine was maintained at 200 to 800 mm. Powder was injected from the nozzle onto the surface of the turbine to remove deposits on the surface of the turbine. Turbine surface 1. When spraying powder of 1% per I;
kg. No wear was observed on the turbine surface after the adhered substances were removed.

In addition, no residual adhering substances were observed on the turbine surface, and no powder was observed adhering to the turbine surface.

The combustion residue of the powder after being used for removal was only about 2% by weight of the powder before combustion.

For comparison, we used sintered alumina of 80 to 150 mesh and removed the adhered substances on the turbine surface under the same conditions as above, and found that there was wear due to the sintered alumina on the turbine surface. Rarely.

By cleaning the surface of a power generation turbine of a boiling water nuclear power generation facility using the method for removing adhered substances of the present invention, the adhered substances are sufficiently removed from the surface of the turbine and no wear is observed on the turbine surface. Ta. In addition, since powder made of thermosetting resin is used, the powder can be burned after use.
By using conventional sintered alumina, the storage amount of incineration residue containing adhering substances could be drastically reduced compared to the conventional blasting method.

[Brief explanation of the drawing]

The figure is a schematic diagram of a blasting device suitable for carrying out the invention. In the figure, lO: powder, 20: blasting device, 22
. . . tank, 24 . . . nozzle, 26 . . . conveyance pipe.

Claims (1)

[Scope of Claims] 1. A method of spraying powder made of a thermosetting resin onto the surface of a power generation turbine of a boiling water nuclear power generation facility together with a gas flow to remove deposits from the surface of the turbine. 2. The method according to claim 1, wherein the thermosetting resin is a melamine resin. 3. The method according to claim 1, wherein the particle size of the powder is 20 to 120 mesh.