JP2004057983A - Filtration equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To continuously supply filtrate without losing liquid by cleaning a filter before holes are fully closed. <P>SOLUTION: In a filtration process for a liquid, a plurality of filters F1 and F2 are arranged in parallel, to filter the liquid. One filter F1 of the filters is set as a non-washing object, and the other side F2 of filters is set as a washing object. The filtrate filtered by the filter F1 of the non-washing object is supplied to both a destination 13 of filtrate supply and the filter F2 of the washing object, and the liquid is flown backward against the filter F2 of the washing object and washing is carried out. The liquid used for washing is returned to the inlet side of a liquid supply pump 11, and is passed through the filtration process again as a part of supply liquid. The liquid pressure on the inlet side of the liquid supply pump 11 is made to be a negative pressure, and the washing object and the non-washing object in the filters F1 and F2 are switched by using a timer. As a result, the liquid can also continuously be supplied to the destination 13 of the liquid supply without losing the liquid and closing the holes of the filter. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a filtering device, and more particularly to a filtering device that filters liquids such as water, seawater, and chemicals.
[0002]
[Prior art]
When the filter is clogged during use of the filter device, generally, the filter device is disassembled and cleaned or the filter cartridge is replaced. Conventionally, as a cleaning method of the filter, a method of peeling the attached matter of the filter by pressurizing the secondary side region on the filtrate side through the filter, or a method of peeling off the attached matter by generating bubbles around the filter In addition, there is a method of peeling off deposits by causing the filtrate to flow backward with respect to the filter.
[0003]
Among these washing methods, washing by backflow of the filtrate is superior to other washings from the viewpoint of washing ability. In particular, in JP-A-11-156115, a plurality of filtration devices arranged in parallel are used. A method has been proposed in which backwashing is performed to simplify the apparatus structure.
[0004]
[Problems to be solved by the invention]
However, even in the cleaning method of the above publication, since the liquid to be filtered cannot be sent to the filter during the backflow cleaning, the filtration must be temporarily stopped and the filtrate obtained through the filtration process can be washed. However, there is a problem such as a large liquid loss because it is discarded after being used in large quantities. Further, when the filter hole is completely blocked, there is also a problem that the filter hole is not completely restored even if it is backwashed for a long time, so that it cannot be used in the next filtration process.
[0005]
The present invention has been made in view of the above-mentioned problems, and by continuously clogging the filter by suppressing clogging of the filter of the filtration device and extending the lifetime, and further suppressing the loss of the liquid used for backflow cleaning, It aims at providing the filtration apparatus which can carry out filtration.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the filtration device of the present invention is a filtration device in which a plurality of filters are arranged in parallel in the middle of a pipe connecting a supply unit for supplying a liquid and a supplied part to which the liquid is supplied. The liquid is sent by a liquid supply pump installed downstream of the supply unit, and is filtered by flowing the liquid from the primary side region before filtration to the secondary side region after filtration through the filter. In the filtration device, at least one of the filters is to be cleaned and at least one other filter is not to be cleaned, and a part of the liquid filtered by the filter to be cleaned is removed from the secondary side of the filter to be cleaned The filter is sent to the region and backflowed to the primary side region to wash the filter, and the liquid used for the washing is returned to the supply unit.
[0007]
The cleaning target filter and the non-cleaning target filter are alternately switched, and filtration is continued during cleaning. In addition, it is preferable that the filtrate that has flowed back through the filter to be cleaned is returned to the inlet side of the feed pump, and the inlet side of the feed pump is set to a negative pressure. Switching between the filter to be cleaned and the filter not to be cleaned is preferably performed based on fluctuations in the filtration pressure or at regular intervals. The filter is preferably a SUS wire mesh filter.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
As shown in FIG. 1, the filtration device of the present invention includes a supply tank 10 that supplies liquid, a liquid supply pump 11 that supplies liquid from the supply tank 10, and two filters F <b> 1 that have filters inside. F2, a pipe serving as a liquid supply path, valves V1 to V4 for setting the liquid supply path, a valve V5 for adjusting the pressure, and a valve V6 for adjusting the return amount of the liquid. ing. Hereinafter, in the filters F1 and F2, a region where the liquid before filtration exists is referred to as a primary side region, and a region where the liquid after filtration exists is referred to as a secondary side region.
[0009]
In the present embodiment, the liquid to be filtered is a coating liquid for heat-sensitive recording paper, and has a concentration of 17% by weight or more and 20% by weight or less. Various coating liquids such as a coating liquid having a concentration of 15% by weight to 30% by weight and other coating liquids for overcoat layers, for example, are preferably applied.
[0010]
From the coating liquid supply tank 10, the coating liquid is sent to the liquid supply pump 11 via the liquid feed line P <b> 1. The liquid feed line P1 is provided with a negative pressure adjusting valve V5. The negative pressure adjusting valve V5 maintains the liquid pressure in the liquid feeding line P1 at a negative pressure by reducing the flow rate of the coating liquid.
[0011]
The coating liquid discharged from the pump 11 is sent to the liquid switching unit 12 via the liquid feed line P2. The liquid switching part 12 is configured by connecting four valves V1 to V4 and three branch parts T1 to T3 in series so as to be alternately arranged. A liquid supply line P2 is connected to a branching section T2 that divides the four valves V1 to V4 of the liquid switching section 12 into two. For convenience of explanation, the valves V1 to V4 are referred to as a third valve V3, a first valve V1, a second valve V2, and a fourth valve V4 in order from the left. Further, the first branch portion T1, the second branch portion T2, and the third branch portion T3 are sequentially set from the left.
[0012]
The inlet of the first filter F1 is connected to the branch line P3 of the first branch part T1, and the inlet of the second filter F2 is connected to the branch line P4 of the third branch part T3. Further, the outlets of the first filter F1 and the second filter F2 are connected by a liquid feed line P5, and a branch portion T4 is provided in the liquid feed line P5. A branch line P6 of the branch portion T4 is connected to a supply destination 13, for example, a coating head or a tank.
[0013]
The liquid outlet of the third valve V3 is connected to the liquid supply line P1 at the junction T6 between the pump 11 and the negative pressure adjusting valve V5 via the liquid supply line P7, the branch portion T5, and the liquid supply line P8. Is done. Similarly, the liquid outlet of the fourth valve V4 is connected to the branch portion T5 via the liquid supply line P9. The liquid feed line P8 is provided with a return amount adjustment valve V6. This return amount adjustment valve V6 restricts the amount of coating liquid passing therethrough and adjusts the return amount.
[0014]
Each valve V1-V4 is timer-controlled by a controller (not shown). The valve V5 controls the amount of liquid from the supply tank 10 by a controller or manually so that the pressure of the liquid on the inlet side of the liquid supply pump 11 is negative and constant. Similarly, the return amount adjustment valve V6 adjusts the return amount of the liquid by a controller or manually so that the pressure on the inlet side of the liquid supply pump 11 is negative and constant. As a result, the coating liquid is filtered through the first and second filters F1 and F2, and the filters F1 and F2 are alternately washed.
[0015]
FIG. 2 is a timing chart showing an example of this valve control, and the horizontal axis is time t. One section is 15 seconds, one cycle is composed of four sections, and its length is one minute, but these times may be changed as appropriate. First, in the first section t1, the first valve V1 and the fourth valve V4 are opened, and the second valve V2 and the third valve V3 are closed. In this state, as shown in FIG. 1, the coating liquid is filtered by the first filter F <b> 1 and most of the liquid is sent to the supply destination 13. A part of the filtered coating liquid enters from the outlet side of the second filter F2 and is sent to the inlet side of the liquid supply pump 11 through the fourth valve V4. The backflow of the filtrate eliminates clogging of the filter of the second filter.
[0016]
In the second section t2, the second valve V2 and the fourth valve V4 are switched, the first valve V1 and the second valve V2 are opened, and the third valve V3 and the fourth valve V4 are closed. In this state, as shown in FIG. 3, the coating liquid from the liquid supply pump 11 is sent to the first and second filters F1 and F2, and the coating liquid is filtered by the two filters F1 and F2. Is done. All the filtered liquid is sent to the supply destination 13.
[0017]
In the next third section t3, the first valve V1 and the third valve V3 are switched, the second valve V2 and the third valve V3 are opened, and the first valve V1 and the fourth valve V4 are closed. The In this state, as shown in FIG. 4, the coating liquid is filtered by the second filter F <b> 2 and most of the liquid is sent to the supply destination 13. A part of the filtered coating liquid enters from the outlet side of the first filter F1 and is sent to the inlet side of the liquid supply pump 11 through the third valve V3. The backflow of the filtrate eliminates the clogging of the filter of the first filter F1.
[0018]
In the fourth section t4, the first valve V1 and the third valve V3 are switched, the first valve V1 and the second valve V2 are opened, and the third valve V3 and the fourth valve V4 are closed. In this state, as shown in FIG. 3, the coating liquid from the liquid supply pump 11 is sent to the first and second filters F1 and F2, and the coating liquid is filtered by the two filters F1 and F2. Is done.
[0019]
Hereinafter, by sequentially repeating the first to fourth sections, the filters F1 and F2 are alternately washed, and the clogging of the filter is eliminated. Thereby, the continuous use time of a filter can be lengthened and a coating liquid can be filtered efficiently. In the above embodiment, each section is switched at a constant time using a timer. In addition, a sensor for detecting the filtration pressure is provided in each of the filters F1 and F2, and the filtration pressure is constant. When the value is exceeded, switching of each section may be performed. Furthermore, switching by a timer and switching by a filtration pressure may be used in combination.
[0020]
As described above, the junction T6 is provided on the downstream side of the negative pressure adjustment valve V5 and on the inlet side of the liquid supply pump 11. Thereby, rather than returning the liquid used for cleaning to the supply tank 10, the liquid supply line can be shortened, and thus the apparatus can be made compact. Further, when 10,000 liters of the thermal recording paper coating liquid is processed, according to the conventional method, approximately 100 to 300 liters of liquid is discarded, and this amount is lost. This loss amount roughly corresponds to the filter capacity and the number of filter replacements, which are often determined depending on the size of the filter used. Therefore, the larger the filter capacity, the larger the liquid loss. Become. Therefore, according to the filtration device of the present invention, the cost corresponding to the loss amount can be reduced, and the greater the capacity of the filter, the greater the effect. Further, according to the conventional method, the filter is clogged 5 to 10 times in the filtration process of the thermal recording paper, and the filter needs to be disassembled and cleaned 6 to 11 times. By setting the cycle short, the filters inside the filters F1 and F2 are back-washed before the holes are blocked, so the hole recovery rate by cleaning becomes very high and the filter life is greatly extended. be able to.
[0021]
In order to obtain a sufficient back-flow cleaning effect, in the filtration device of the present invention, the negative pressure adjustment on the inlet side of the liquid supply pump 11 by the negative pressure adjusting valve V5 and the return amount adjusting valve V6, the second side of the filter is adjusted. The differential pressure on the secondary side is preferably set to 0.03 MPa or less. According to this method, the necessary and sufficient amount of liquid for cleaning the filter is ensured by setting the negative pressure on the inlet side of the liquid supply pump 11, so that the liquid can be continuously supplied to the supply destination 13. .
[0022]
Furthermore, the filtration device of the present invention is also effective when three or more filters are installed. That is, it is possible to cope with a case where the amount of liquid to be filtered is large, a case where liquid components are the same, and a mixing ratio is close.
[0023]
Moreover, as a filter inside the 1st and 2nd filter F1, F2, the wire mesh filter made from SUS is used. As a result, the foreign matter blocking the filter hole can be effectively removed by backwashing. In the case of a resin profile filter or a fibrous filter, an obstructed substance tends to enter the depth of the filter hole, and it is often unsuitable in many cases even if it is backwashed. The absolute filtration accuracy of the filter can be appropriately selected according to the type of the filter that closes the filter hole.
[0024]
The filtration device of the present invention can be used for filtration of all liquids including water and seawater. In particular, it is suitable for filtration of a liquid in which an organic compound or an inorganic pigment is finely dispersed in a liquid in which a low molecular compound or a high molecular compound is dissolved using water or an organic solvent. The following viscosity range is preferred. Further, when there are aggregated residues or the like in the liquid, it is particularly effective because the aggregates repeatedly hit the net and are crushed by repeated filtration and backwashing.
[0025]
The polymer compound as the main component of the dispersion includes starches, hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, polyacrylic acid, polyacrylic acid, polymethacrylic acid, Polyacrylic acid ester, polymethacrylic acid ester, polyacrylic acid soda, polyethylene terephthalate, polybutylene terephthalate, chlorinated polyether, allyl resin, furan resin, ketone resin, oxybenzoyl polyester, polyacetal, polyether ether ketone, polyether sulfone , Polyimide, polyamide, polyamideimide, polyaminobismaleimide, polymethylpentene, polyphenylene oxide, polyphenylene Ren sulfide, polyphenylene sulfone, polysulfone, polyarylate, polyallyl sulfone, polybutadiene, polycarbonate, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyurethane, phenol resin, urea resin, melamine resin, melamine formalin Resin, benzoguanamine resin, bismaleimide triazine resin, alkyd resin, amino resin, epoxy resin, unsaturated polyester resin, styrene / butadiene copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer, ethylene / acetic acid Vinyl copolymer, acrylic acid amide / acrylic acid ester copolymer, acrylic acid amide / acrylic acid ester / methacrylic acid terpolymer, Examples include alkali salts of len / maleic anhydride copolymers, alkali salts or ammonium salts of ethylene / maleic anhydride copolymers, and other various polyolefin resins. These may be used alone or in combination. be able to.
[0026]
【Example】
EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated concretely, this invention is not limited to this. A coating solution for heat-sensitive recording paper was prepared with the following composition and filtered with two filters F1 and F2.
Dispersant / surfactant (2% by weight aqueous solution) 5 parts by weight waxes (25% by weight aqueous solution) 7 parts by weight organic compound 22 parts by weight inorganic pigment 5 parts by weight polyvinyl alcohol (9% by weight aqueous solution) 35 parts by weight water 26% by weight Department [0027]
The first and second filters F1 and F2 have a capacity of 20 liters and a filter aperture of 100 μm. The filtration throughput is 10 m ³ . Switching between washing and non-washing of the filters F1 and F2 was performed with 1 cycle as 1 minute. As a result of this example, the supply of the filtrate to the supply destination was continuously performed, the clogging of the filter was not confirmed in both the filters F1 and F2, and the filter was not required to be disassembled and washed. In addition, there is no liquid loss due to backwashing.
[0028]
【The invention's effect】
As mentioned above, the filter can be washed without stopping the supply of the filtrate to the supply destination by the filtration device of the present invention. Furthermore, since complete blockage of the filter hole is suppressed, it is possible to greatly extend the life of the filter and continuously perform stable filtration.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a circuit diagram showing a liquid feeding path, which is a filtration step according to an embodiment of the present invention.
FIG. 2 is a timing chart showing a valve switching operation in a liquid switching unit in a filtration process.
FIG. 3 is a circuit diagram showing another liquid feeding path in the filtration step.
FIG. 4 is a circuit diagram showing another liquid feeding path in the filtration step.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Supply pump 12 Liquid switching part 13 Supply destination F1 1st filter F2 2nd filter V1 1st valve V2 2nd valve V3 3rd valve V4 4th valve V5 Return amount adjustment valve V6 Negative pressure adjustment valve

Claims (6)

A filtration device in which a plurality of filters are arranged in parallel in the middle of a pipe connecting a supply unit for supplying a liquid and a supplied part to which the liquid is supplied, and the liquid is installed downstream of the supply unit In the filtration device that is sent by the liquid supply pump and filtered by flowing the liquid from the primary side region before filtration to the secondary side region after filtration through the filter,
At least one filter is to be cleaned and at least one other filter is not to be cleaned, and a part of the liquid filtered by the non-cleaning target filter is placed in the secondary region of the filter to be cleaned. A filtration device, wherein the filter is cleaned by feeding and flowing back to the primary side region, and the liquid used for the cleaning is returned to the supply unit. 2. The filtration apparatus according to claim 1, wherein the filter to be cleaned and the filter to be not cleaned are alternately switched to continue filtration during cleaning. The filtration apparatus according to claim 1 or 2, wherein the filtrate that has flowed backward through the filter to be cleaned is returned to the inlet side of the liquid supply pump. The filtration device according to any one of claims 1 to 3, wherein an inlet side of the liquid supply pump is set to a negative pressure. The filtration device according to any one of claims 1 to 4, wherein switching between the filter to be cleaned and the filter to be not cleaned is performed based on a change in filtration pressure or at regular intervals. 6. The filtering device according to claim 1, wherein the filter is a SUS wire mesh filter.

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