JPH10180143A - Cake scraping and removing apparatus for centrifugal filtration apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably scrape a cake layer by a scraping knife and recover cakes with little liquid from a discharge chute by installing and fixing gas jetting pipes to jet a pressure gas in the rear side of the scraping knife as to jet the pressure gas along the edge of the scraping knife. SOLUTION: A plurality of gas jetting pipes 9 installed and fixed in the rear side of the scraping knife 4 so as to jet the pressure gas along the edge of the scraping knife 4 are connected with a pressure gas supply pipe 8. Then, these gas jetting pipes 9 are extended to the points at which their tip ends slightly touch the inclining part of the edge of the knife and fixed by a proper method such as welding, fastening by screws. Consequently, it is unnecessary to scrape cakes while leaving a base layer as to prevent damage on the scraping knife 4 and a filter cloth 3 and the whole cakes can reliably be recovered with a dry process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a case for a centrifugal filter.
This invention relates to a scraping and removing device.

[0002]

2. Description of the Related Art In a conventional centrifugal filter and a basket type centrifugal filter, as shown in a longitudinal sectional view of FIG. 6, a stock solution supplied into a rotating basket 2 through a supply pipe 6 of a stock solution to be processed is Under the action of centrifugal force, the filtrate is turned into a rotating basket 2
Is passed through the filter cloth 3 attached to the inner peripheral surface of the filter cloth and is discharged to the outside of the basket. The solids settle and deposit on the filter cloth to form a cake layer, and a predetermined cake is deposited. At this stage, the rotating speed is reduced, the cake layer is scraped off by the scraping knife 4, and the cake layer is discharged to the outside of the basket through the discharge shot 7.

In the above, usually, the cake is scraped and discharged while leaving a thin cake layer so as not to damage the filter cloth with a scraping knife, but this operation is repeatedly performed for a long time. In the meantime, the remaining cake layer forms a hard layer (hereinafter, referred to as a base layer), increasing the filtration resistance and lowering the filtration efficiency.

[0004] Conventionally, when the above condition is reached or every predetermined operation time, the rotation of the rotating basket is stopped or the rotation speed is reduced, and the base layer is peeled off by a backwashing operation of supplying water from the back of the filter cloth. Further, the pressurized water is sprayed onto the surface of the base layer to peel off the slurry, the cake is slurried, and the slurry is discharged to the outside of the basket by skimming discharge or overflow discharge by a skimming tube.

[0005] The applicant of the present invention has disclosed in Japanese Patent Laid-Open No. Hei 5-3177.
In the method disclosed in No. 54, as shown by a dashed line in FIG. 6, a pressure gas injection nozzle 9 is provided at a constant interval in the inner circumferential direction with respect to the scraping knife, and the rotation speed is reduced, The base layer is peeled by injecting a pressure gas into the layer, and the peeled cake is conveyed to a scraping knife by rotating a rotating basket, scraped by a scraping knife and discharged.

[0006]

SUMMARY OF THE INVENTION In the above-mentioned method of removing the base layer by slurrying the cake, the cake is reliably formed.
The filter can be removed and the filter cloth surface can be washed, but the discharged slurry
Re-treatment such as waste water treatment or solids recovery is necessary, the amount of treatment is relatively large, and equipment costs are increased.In addition, pressure gas is injected at a fixed interval from the scraping knife. The method of removing the base layer by drying is preferable because it is of a dry type and the same cake as the filtration and recovery cake can be collected and there is no need for reprocessing. However, the peeled cake is located above. It is not easy to drop without reaching the scraping knife portion, and it is not easy to scrape with the scraping knife and discharge from the discharge shoot, and the cake may stay in the basket while rotating. .

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above-described problems in an apparatus used in a method for scraping and removing a base layer formed on a filter cloth surface of a basket of a conventional centrifugal filter, and thus the cake layer is reliably scraped. The cake of a centrifugal filter that can scrape with a removing knife and collect the cake with a small amount of liquid from the discharge shot, and can be applied not only to the removal of the base layer but also to the cake layer itself. -It has been made for the purpose of providing a scraping and removing device.

[0008]

To achieve the above object, the gist of the present invention is to provide a cake layer formed on a filter cloth surface of a rotary basket of a centrifugal filter. Centrifugal filter, characterized in that a gas injection pipe for injecting pressure gas is fixed to the back side of the scraping knife so that the injected gas is ejected along the cutting edge of the scraping knife. Is a cake scraping and removing device.

Further, in the invention described in claim 2, a groove is provided on the back side of the scraping knife in the cake scraping and removing device, in which a tip of a gas injection pipe for injecting a pressure gas is fitted. The cake scraping and removing apparatus is characterized in that a tip portion of the gas injection pipe is fitted and fixed in the groove.

[0010] In the above construction, the pressurized gas is injected along the scraping knife section, so that the cake layer or / and / or the like is formed at the scraping section.
The cake is scraped with a scraping knife at the same time as the peeling, and the cake can be dropped and collected on a discharge shot, so that the scraping knife and the filter cloth are separated. It can be scraped off by holding it at regular intervals, and it is not necessary to scrape the cake with a scraping knife leaving the base layer so as not to damage the filter cloth. A small amount of cake can be recovered. Also, since the cake layer and / or the base layer is peeled off by the scraping knife, the peeled cake is removed.
There is no danger that the key will fall into the rotating basket outside the discharge shot, and there is no danger that the cake will stay in the rotating basket.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a longitudinal sectional view of one embodiment of the present invention, FIG. 2 is a partial longitudinal sectional view of the front of FIG. 1, FIGS. 3, 4 and 5 are perspective views of a scraping knife portion, and FIG. It is a longitudinal section of a centrifugal filter. Note that the same reference numerals are used for members common to the drawings.

Reference numeral 1 denotes a casing of a centrifugal filter main body in which the rotating basket 2 is supported via a bearing 10 as a cantilever lever and is incorporated.
The rotating basket 2 is configured to be rotated at a high speed by rotation driving means (not shown) via a rotating shaft supported by a bearing 10. Reference numeral 3 denotes a filter mounted on the inner periphery of the rotating basket 2. It is cloth. Reference numeral 4 denotes a scraping knife, which is fixed to the tip of the knife box 5 and whose angle is adjusted by the knife arm 11 so as to be separated from and brought into contact with the scraping surface. The knife box 5 has the function of introducing the scraped cake to the cake discharge seat 7 arranged below.

Reference numeral 6 denotes a supply pipe for the undiluted solution to be processed, which supplies the undiluted solution toward the filtration surface in the rotating basket 2. Reference numeral 8 denotes a pressure gas supply pipe, which is connected to a gas injection pipe 9 fixed to the back surface of the scraping knife 4 for jetting a pressure gas. The back side of the scraping knife 4 refers to the surface opposite to the cake scraping surface. Normally, the scraping knife 4 is a single-edged knife, with the inclined side being the back side.

In the method of fixing the gas injection pipe 9 fixedly provided on the back side of the scraping knife 4 so that the injection gas is ejected along the cutting edge of the scraping knife 4, FIG. A plurality of gas injection pipes 9 are extended along a knife guide 4a for fixing and reinforcing the knife provided until the tip slightly reaches the inclined portion of the cutting edge, and fixed by an appropriate method such as welding or screwing. . If the gas injection pipe 9 is disposed on the surface of the cake scraping surface, the cake scraped from the gas injection port at the tip may enter and block the gas injection pipe 9.

Further, the gap between the back surface inclination of the cutting edge of the scraping knife 4 and the filter cloth 3 is extremely small, and even if a part of the gas injection pipe 9 projects outside the inclination angle, it comes into contact with the filter cloth 3. If there is a possibility of damaging the filter cloth 3, as shown in FIG. 4 or 5, a groove 13 into which the tip of a gas injection pipe 9 for injecting a pressure gas is fitted on the back side of the scraping knife 4. 13a, it is preferable that the tip of the gas injection pipe 9 is fitted in the grooves 13 and 13a and fixed so as not to protrude from the back surface inclined angle of the blade of the scraping knife 4. In FIG. One parallel groove 13 is provided. In FIG. 5, grooves 13 a perpendicular to the cutting edge are provided by the number of gas injection pipes 9.
As shown in FIG. 4, a hole formed by drilling a middle portion of the gas injection pipe 9 into the knife guide 4 a may be inserted or the hole may be used as a middle pipe of the gas injection pipe 9. However, the mounting structure of the gas injection pipe 9 in the centrifugal filter of the present invention is not limited to the above configuration.

In the centrifugal filter having the above structure, the stock solution supplied into the rotating basket 2 rotating from the supply pipe 6 for the stock solution to be treated is subjected to the action of centrifugal force, and the filtrate is concentrated in the rotating basket 2.
Through the filter cloth 3 adhered to the inner peripheral surface of the casing 1 and discharged from the casing 1 to the outside by a skimming device or the like (not shown),
The solid content is settled and deposited on the filter cloth 3 to form a cake layer 12. When a predetermined cake is deposited, the rotation speed is reduced, and the cake layer 12 is scraped off by the scraping knife 4. , K
The key is discharged to the outside of the rotating basket through the discharge shot 7.

In the above, the case is cut by the scraping knife 4.
By scraping the key layer 12 and injecting a pressure gas along the scraping knife 4 from a plurality of gas injection pipes 9 provided on the back surface of the scraping knife 4, the cake layer or /
The cake is scraped off by the scraping knife 4 at the same time as the peeling, so that the cake can be dropped and collected on the discharge port 7.

Accordingly, the scraping knife 4 and the filter cloth 3 can be separated and held at a predetermined interval to perform the scraping. Unlike the conventional technique, the scraping knife 4 leaves the base layer so as not to damage the filter cloth. -There is no need to scrape the keys, and all the cakes can be reliably collected in a dry manner. In addition, since the cake layer or the base layer is peeled off by the scraping knife 4 part, there is no possibility that the peeled cake falls into the rotating basket outside the discharge shot, so that the cake is put into the rotating basket. There is no danger of staying. In the above description, the operation of scraping the cake layer is performed by lowering the rotation speed of the rotating basket. However, it is also possible to perform the scraping operation at a high speed as in the case of centrifugal filtration.

However, for the sake of safety, the cake is scraped off leaving a thin cake layer as in the prior art, and the remaining cake layer 1 is removed.
When the solid base layer 2 has formed a solid base layer or at a predetermined operating time, the rotation speed is reduced, and a pressurized gas is injected from the gas injection pipe 9 along the scraping knife 4 to thereby form the base layer. The removal may be performed.

[0020]

According to the present invention, since the cake layer is peeled by injecting a pressure gas at the scraping knife portion, the dry type is surely scraped with the scraping knife and the liquid content from the discharge shot is small. The cake can be recovered and can be applied not only to the removal of the base layer but also to the removal of the cake layer itself.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention.

FIG. 2 is a partial longitudinal sectional view of the front of FIG. 1;

FIG. 3 is a perspective view of a scraping knife unit according to the embodiment;

FIG. 4 is a perspective view of a scraping knife portion according to another embodiment.

FIG. 5 is a perspective view of a scraping knife portion according to another embodiment.

FIG. 6 is a longitudinal sectional view of a conventional centrifugal filter.

[Explanation of symbols]

 1: casing 2: rotating basket 3: filter cloth 4: scraping knife 4a: knife guide 5: knife box 6: supply pipe for stock solution to be treated 7: discharge discharge of cake 8: supply of pressurized gas Pipe 9: Gas injection pipe 10: Bearing 11: Knife arm 12: Cake layer 13, 13a: Groove

Claims (2)

[Claims] In a device for scraping and removing a cake layer formed on a filter cloth surface of a rotating basket of a centrifugal filter, a gas injection pipe for injecting a pressure gas is supplied along a cutting edge of a scraping knife. A cake scraping and removing device for a centrifugal filter, wherein the device is fixed to the back side of a scraping knife so as to be ejected. 2. A scraping knife is provided with a groove on a rear surface side thereof for fitting a tip of a gas injection tube for injecting a pressure gas, and a tip of the gas injection tube is fitted and fixed in the groove. The cake scraping and removing device for a centrifugal filter according to claim 1, wherein: