JPH0640937B2 - Liquid filtration method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a liquid filtration method, and more particularly, it is formed by pre-coating an upright cylindrical or prismatic filter element (filter material) with a filter aid. The present invention relates to improvement of a method for filtering a liquid by a precoat layer. This filtration method is applied to the production of beer, sake, wine and other liquors; soy sauce, vinegar, sugar, edible oils and other seasonings; fruit drinks, carbonated drinks, mineral water, oolong tea and other drinks; pharmaceuticals and other substances. It

[Conventional technology and its problems]

As one of filtration methods, there is a method in which a filter element is precoated with a filter aid such as diatomaceous earth, perlite, cellulose, or activated carbon, and a liquid is filtered by the formed precoat layer.

In this case, a filter cloth, filter mesh, filter paper or the like is generally used as the filter element for forming the precoat layer, but a punch metal, a corrugated polygonal tube wound with a spiral wire, a ceramic cylindrical element or the like may be used alone or May be used in combination.

When a cylindrical or prismatic filtration element is used upright, there are a method of withdrawing the filtrate filtered by the precoat layer from the upper portion of the element and a method of withdrawing it from the lower portion. But,
In any case, since the precoat layer is formed on the surface in the vertical direction, not only when precoating the element with the filter aid, but also when the flow of the fluid stops when performing filtration with the formed precoat layer, the precoat layer is formed. The layers may peel and fall.

Further, when performing filtration with a precoat layer, when forming the precoat layer, a method of using a liquid to be filtered from the beginning is also known, but the components eluted from the filter aid are mixed in the filtrate at a certain value or more. If it does not occur or if there is no microbial contamination in the filtration system, it may cause problems if the liquid to be filtered is run from the beginning. Therefore, in such a case, a liquid different from the liquid to be filtered, such as water,
A method of forming a precoat layer using hot water or the like and then switching to a liquid that should not be filtered without stopping the flow is adopted.

In this case, there occurs a portion where the liquid (water, hot water, etc.) used for forming the precoat layer and the filtrate of the liquid to be filtered are mixed, and since this portion has a low concentration of the filtrate, it is discarded or this portion is temporarily separated. It is practiced to collect them in a container and return them to the previous process little by little.

However, when the liquid to be filtered is valuable or inconvenient to discard, it is necessary to avoid discarding the liquid to be filtered. Therefore, collecting the mixed portion in another container and then reprocessing it requires equipment, manpower, time, etc.,
Not economically favorable.

As a method for avoiding the occurrence of the mixed portion as described above, there is a method in which after the formation of the precoat layer on the filter medium is completed, the inside of the apparatus is pressurized with a gas such as air or carbon dioxide, and the liquid used for the precoat is discharged. is there.

However, it is difficult to maintain the precoat layer in a perfect state because part of the precoat layer is peeled off or fine holes are formed in the precoat layer at the stage of inserting the liquid to be filtered after discharging the liquid. . In particular, such inconvenience is likely to occur when the filtrate is withdrawn from the lower part of the device.

[Means for solving problems]

Therefore, the present inventors pre-coated a filter aid in a standing cylindrical or rectangular tubular filter element, the method of filtering the liquid by the formed pre-coat layer, in the filtration method does not occur the mixing portion The present invention has been achieved as a result of studies to develop a filtration method that does not cause the above-mentioned inconvenience.

The present invention is a method of pre-coating a filter aid in a standing cylindrical or prismatic filter element with a filter aid, and filtering the liquid by the formed pre-coat layer. While being supplied, the liquid used for the precoat is discharged from the inside of the filtration device, and after the discharge is completed, the pressure difference between the primary side and the secondary side of the filtration element is 0.1 to 1.
The present invention provides a liquid filtration method characterized in that a liquid to be filtered is put into a filtration device while exhausting from a secondary side (inside of a filtration element) so as to be 0 kg / cm ² .

That is, in the present invention, prior to the filtration of the liquid to be filtered, a liquid (water, hot water, etc.) different from the liquid to be filtered is pre-coated, and after the formation of the pre-coated layer is completed, a gas such as air or carbon dioxide gas is used. After pressurizing the inside of the device and discharging the liquid used for precoating,
When the liquid to be filtered is introduced into the filtering device to carry out filtration, the liquid to be filtered is put into the device while exhausting it from the inside of the filter element, and the liquid to be filtered is filled in the device and the filtration is started at the same time.

As described above, if the liquid flow stops during precoating or filtration, the precoat layer may peel off and fall.
In order to prevent the precoat layer from coming off, when the precoat layer is in contact with the liquid, the liquid must always flow from the primary side, that is, the filtered liquid inlet side to the secondary side, that is, the filtrate outlet side. I won't.

Since the liquid always flows from the primary side to the secondary side during precoating, the precoat layer does not come off, and when gas such as air and carbon dioxide gas is fed in to pressurize the inside of the device in the next stage, If the precoat liquid is extracted from the secondary side, the precoat layer does not peel off.

However, in order to filter the liquid to be filtered after the precoat liquid is extracted from the device in this way, when the liquid to be filtered is applied to the filtering device in the next step, the pressure difference between the primary side and the secondary side is increased. It is difficult to carry out while keeping above a certain value. for that reason,
In the case of the conventional method, it was unavoidable that a part of the precoat layer was peeled off at this stage or that fine holes were formed in the precoat layer.

That is, when the liquid to be filtered is squeezed into the filtration device while exhausting it from the exhaust pipe provided on the primary side, the pressure difference between the primary side and the secondary side cannot be maintained at a predetermined value. Therefore, the flow of the liquid from the primary side to the secondary side is stopped, and the precoat layer easily peels off. Also, when the liquid is pulled out from the filtrate withdrawal pipe at the bottom of the filter element and the liquid is pulled in, the precoat layer does not peel off in the first part, but in the latter half, the gas remaining inside the filter element loses its escape and loses its element. Since it comes out from the inner side (secondary side) to the outer side (primary side), fine holes are likely to occur in the upper part of the precoat layer.

In order to solve such inconvenience, according to the present invention, an exhaust hole is provided on the secondary side so that it can be exhausted to the outside of the apparatus by connecting to an exhaust pipe so that the pressure difference between the primary side and the secondary side is 0.1 to 1.0. Kg / cm ² ,
Desirably, the liquid to be filtered is put in while exhausting from the secondary side so as to be 0.2 to 0.5 kg / cm ² . This makes it possible to pour the liquid to be filtered into the filtration device while keeping the precoat layer in a perfect state.

Filtration is started at the same time when the liquid to be filtered is full in the apparatus, but during filtration, the liquid always flows from the primary side to the secondary side, so the precoat layer does not fall off.

When it is desired to finish the filtration, a gas such as air or carbon dioxide gas is fed again to pressurize the inside of the apparatus and the filtrate is extracted from the secondary side, so that the precoat layer does not peel off.

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a flow sheet illustrating a filtration system for carrying out the present invention.

The filtering device 1 has a cylindrical or rectangular tubular filtering element 2
Is erected, and an exhaust pipe 3 communicating with the inside of the element is connected to the upper portion of the element 2. In the figure, 4 is a liquid supply line, 5 is a filtrate extraction pipe, 6 is a liquid extraction line, 7 is a gas introduction line, 8 is a primary side exhaust pipe, 9 is a precoat tank, 10 is a pump, and 11a to 11j are. Each valve is shown.

In the present invention, the filter medium, that is, the filter element may be any one having a cylindrical shape or a square shape, and any known filter medium can be used. In particular, a ceramic cylindrical element,
Punch metal or an element in which a spiral wire is wound around a corrugated polygonal tube is suitable. The height, wall thickness, inner diameter, and other dimensions of the filter medium and the number of filter mediums installed upright in the apparatus may be appropriately determined in consideration of the purpose of use. In the present invention, the above-mentioned shape of a cylinder or a square tube includes a deformation of a cylinder or a square tube or a shape similar thereto.

[Action]

By adopting the method of the present invention, it is possible to maintain the precoat layer in a perfect state from the beginning to the end of the filtration, it becomes possible to perform precise filtration, and the liquid used for forming the precoat layer and the coating It is possible to perform filtration without generating a mixed portion of the filtrate of the filtrate.

[Example 1] Example 1 Ceramic cylindrical element (height 500 mm x 3 steps, wall thickness 25 mm, inner diameter 70 mm) 19
Assembling the filter into a filtration system, as shown in Fig. 1, in which a book is erected upright, an exhaust hole (inner diameter 7 mm) is provided on the upper part of each element fixing spindle, and it is connected to an exhaust pipe to allow exhaust to the outside of the device. The following tests were conducted in detail.

A suspension of 35 Kg of diatomaceous earth in water was drawn into the precoat tank 9 and circulated in the path of the valve 11b, the pump 10, the valve 11c, the filtration device 1, the extraction pipe 5, the valve 11j and the precoat tank 9. The outer periphery of the cylindrical element was precoated with diatomaceous earth. The flow rate in the precoat was 12 to 13 k / hour, and the solution was circulated for 30 minutes.

After pre-coating is completed, valve 11b and valve 11j
Close the valve and stop the pump 10, and at the same time, the valve 11f
Was opened, 2.0 kg / cm ² of carbon dioxide gas was fed into the filtration apparatus 1, and the valve 11i was opened to discharge the precoat water. At this time, the valve 11i is not fully opened and the discharge flow rate is 5 to 6 k.
It was discharged while adjusting the valve opening so that it became / hour.

When the liquid level in the filtration device reached the position of the extraction pipe 5, the valve 11d was opened to completely drain the residual water. Also at this time, the valve 11d was not fully opened, and the valve was opened while adjusting the valve opening so that the discharge flow rate was 5 to 6 k / hour. When the inside of the apparatus becomes empty, the valve 11c is closed. Also, the valve 11
The e was opened while squeezing, and the residual water slightly remaining in the exhaust pipe was discharged.

Further, in order to discharge the precoat water remaining in the pipe between the valve 11a and the valve 11d, the valve 11a and the valve 11d were opened for several seconds and then closed.

Next, beer was poured into the filtration device through the route of the valve 11a, the pump 10, the valve 11c, and the filtration device 1. At this time, the beer was added while the valve 11e of the secondary exhaust pipe 3 was opened and exhausted. The valve 11f is closed. At this time, squeeze the valve 11e without fully opening it, and
The pressure on the secondary side was adjusted to 1.5 to 1.8 Kg / cm ² . Also, the pressure difference between the primary side and the secondary side (differential pressure) is 0.3 to 0.4 Kg / c.
The opening of the valve 11c was adjusted so as to be m ² .

If beer overflows from the secondary exhaust pipe, valve 11g
I opened it up a little and kept the beer in the filter until it was full. Also in this case, the openings of the valves 11c and 11g were adjusted so that the differential pressure was 0.3 to 0.4 kg / cm ² .

After the installation is completed, the valves 11e and 11g are closed and at the same time, the valve 11h is opened to open the valve 11a and the pump 1.
The beer was filtered through the route of 0, valve 11c, filtration device 1 and valve 11h. The filtration may be performed at any flow rate during filtration, but care should be taken to prevent sudden pressure fluctuations.

After reaching the required filtration amount, open the valve 11f to feed 0.2 kg / cm ² of carbon dioxide gas into the filtration device, and pump 1 at the same time.
0 is stopped, the valve 11a and the valve 11c are closed, and the beer remaining in the filtering device is pushed out through the path of the filtration extraction pipe 5 and the valve 11h. At this time, the valve 11h was not fully opened, and was discharged while adjusting the valve opening so that the discharge flow rate was 5 to 6 k / hour.

When the liquid level of beer in the filtration device reached the position of the filtrate withdrawal pipe 5, the valves 11c and 11d were opened, the valve 11h was closed, and the beer remaining in the lower part of the filtration device was recovered.

As a result, the beer could be filtered without generating the mixed portion of water and beer used in the precoat, and the yeast contained in the beer was completely removed by the filtration. Further, neither peeling of the precoat layer nor generation of fine pores was observed during the filtration operation.

The microbe test results in beer before and after filtration were as follows.

Comparative Example 1 A filter having no secondary side exhaust pipe 3 was used as the filter device, and the valve 11 of the primary side exhaust pipe 8 was used when beer was poured.
g or another valve 11i was opened and air was squeezed in while exhausting, the pressure difference between the primary side and the secondary side was not sufficient, the precoat layer was partially peeled off, or fine holes were formed in the upper part of the precoat layer. However, satisfactory filtration could not be performed.

Comparative Example 2 The same filtering device as in Example 1 was used, and the operations up to the step of adding beer to the filtering device were performed in the same manner.

After that, when beer is added, the pressure difference between the primary and secondary sides
When the valve opening was adjusted to be less than 0.01 kg / cm ² , fine holes were formed in the upper part of the precoat layer.

Example 2 One ceramic cylindrical element (height 500 mm × 3 steps, wall thickness 25 mm, inner diameter 70 mm) was erected, and an exhaust hole (inner diameter 7
mm), and a filtration device to which an exhaust pipe was connected was incorporated into the filtration system as shown in FIG.

Then, the molasses instead of beer, was filtered using air 1.8 kg / cm ² instead of carbon dioxide 2.0 Kg / cm ^2.

The amount of diatomaceous earth used is 2 kg, and the flow rate in the precoat is 650
700 / hour, the flow velocity at the time of precoat water discharge is 250 to 3
00 / hour, the secondary pressure at the time of extension is 1.1 to 1.5 kg / c
m ² , the differential pressure between the primary side and the secondary side is 0.4 to 0.5 Kg / cm ² , and the flow rate at the time of pushing out the sugar solution remaining in the filtration device after the filtration is 250
Filtration was performed in the same manner as in Example 1 except that the time was set to 300 / hour.

As a result, it was possible to filter without lowering the sugar solution concentration due to mixing with water, and to completely remove the yeast in the sugar solution.

The results of microbiological tests in the sugar solution before and after filtration were as follows.

Example 3 Wavy polygonal tube (height 700 mm, wall thickness 2 mm, inner diameter 26 mm)
Oolong tea was filtered using the same filtering device as in Example 1 except that seven wound spirally wound elements were used as the filter medium. Instead of carbon dioxide 2.0 Kg / cm ^2, using nitrogen gas 1.5 Kg / cm ^2, 1.6 Kg usage diatomaceous earth, the flow rate in the precoat 550-600 /
When the precoat water is discharged, the flow rate is 200 to 250 /
At the time of squeezing, the secondary side pressure is 1.0 to 1.3 Kg / cm ² , the differential pressure between the primary side and the secondary side is 0.2 to 0.3 Kg / cm ² , when the oolong tea remaining in the filtration device after the filtration is pushed out Flow rate of 200 to 2
Filtration was performed in the same manner as in Example 1 except that the time was 50 / hour.

As a result, it was possible to carry out filtration without lowering the concentration due to mixing with water, and it was possible to completely remove the bacteria contained in the oolong tea.

The results of the microbial test in the oolong tea before and after filtration were as follows.

[Advantages of the Invention] By adopting the filtration method of the present invention, after the precoat layer is formed on the filter medium, even if the liquid to be filtered is put in after the fluid in the device is extracted, the precoat layer may be peeled or fine pores may be generated. Does not happen. Therefore, filtration can be performed without producing a portion where the liquid to be filtered is mixed with the liquid used for the precoat. Therefore, it is not necessary to dispose or reprocess a part of the filtrate, so that the cost can be reduced and a product with improved quality can be obtained.

[Brief description of drawings]

FIG. 1 shows a flow sheet of a filtration system used in the embodiment of the present invention. 1 ... Filtration device, 2 ... Filtration element, 3 ... Exhaust pipe, 4 ... Liquid supply line, 9 ... Precoat tank

Claims (1)

[Claims] 1. A method of pre-coating a vertically-arranged cylindrical or prismatic filter element with a filter aid and filtering a liquid by the formed pre-coat layer, wherein a pressurized gas is provided in the filtration device after the pre-coat layer is formed. While discharging, the liquid used for the precoat is discharged from the inside of the filtration device, and after the discharge is completed,
The pressure difference between the primary side and the secondary side of the filter element is 0.1
A liquid filtration method characterized in that the liquid to be filtered is put into the filtration device while exhausting from the secondary side so as to be 1.0 kg / cm ² .