FI103325B - Clear filter and regeneration process - Google Patents

Description

103325

BACKGROUND OF THE INVENTION The present invention relates to a clarifying filter comprising a cylindrical filter element in a container having a fluid flow to be filtered through a jacket such that the solids in the liquid are separated into a cake on the surface of the element, flowing into the container and and for regenerating the filter element of the ultrasonic cleaner connected to the ultrasonic generator. The invention further comprises a method for regenerating a filter element of a clarifying filter.

10 The purpose of clarification filtration is to separate as small as possible the small solid particles in the liquid so that a clear filtrate is obtained. The particle size ranges from a few micrometers to a few micrometers, and the solids in the liquid can range from 1 mg / l to 10 g / l. For the smallest particles to be distinguished from the liquid, the pores of the filter material must be small enough, in most cases less than 5 μπι.

The purpose of clarification filtration may be to purify the liquid of a solid which would reduce the quality of the liquid for use or further processing. Alternatively, the goal may be to recover a valuable solid.

In order for the leachate filtration process to be economically viable, its capacity should be high and as smooth as possible. The problem with filtration is that when filtering small colloidal particles, they tend to block the micropores of the filter material in a short period of time. The large surface area of the pores adsorbs small particles, ions, or molecules from the fluid flowing through, thereby reducing the volume of the pores. Particularly susceptible to clogging is the surface of the filter material, which interacts with the solid that accumulates in its vicinity. The surface may be mechanically blocked by particles of suitable size that penetrate into the surface pores of the material, or the particles may bind to the surface of the material by chemical or electrical bonding. · As a result of clogging, the original high capacity of the clean filter material quickly drops to a fraction of its original size, requiring the filter material to be replaced or regenerated.

Batch filters for clarification filtration are available on the market in which the filter medium must either be completely replaced or removed for purification after clogging. This procedure is laborious and causes low utilization. There are also filters that use coarser 2 103325 data medium (5-10 μιη) to avoid clogging, but the resulting filtrate is not sufficiently pure. Good filtration results are obtained with known membrane and osmosis filters, but their capacity is small and the membrane replacement requires manual labor.

The most common procedure for regenerating clarification filters has been to reverse invert, in which the liquid is pressed in the opposite direction to the filtration direction at a pressure which should be greater than the pressure at which the filtration occurs. However, this can be difficult to accomplish and the method is unable to remove nearly all of the particles clogging the filter material. Another commonly used Rege inerification method has been the chemical washing of the filter material with a solution in which the blocking agent is dissolved.

The regeneration of the filter material can also be performed by ultrasonic cavitation, which causes a high mechanical wear on the surface of the material, which consumes the blocking material.

In the clarification filter according to the invention, the regeneration of the filter-tin element by ultrasound has been further developed with the aim of enabling rapid cleaning of the filter without significant production interruption. The filter according to the invention is characterized in that the ultrasonic cleaner is formed as a ring surrounding the filter element which, when cleaning, can be moved from top to bottom along with the liquid surface in the container.

The ring-shaped ultrasonic cleaner of the invention purifies by cavitation one of the horizontal zones of the filter element. The purifier floats in the liquid to be filtered at its normal starting position near the top of the tank. As the cleaner is subsequently moved by lowering the surface of the liquid in the tank slowly from top to bottom, the entire surface of the element is cleaned by ultrasonic cavitation during the operation. If necessary, cleaning can also be repeated. The cleaning can be done only with ultrasound or it can be combined with washing with water or similar washing liquid. The entire cleaning event can be programmed automatically so that the time between two cleaning sessions can be adjusted within wide limits.

The liquid level in the tank may be lowered via the drain valve 30 at the bottom of the tank.

Between the ultrasonic cleaning steps, the clarifying filter of the invention can be cleaned by reverse rinsing with washing liquid. The filter may be constructed so that the filtrate outlet line begins at the top of the container, is connected to the container to provide a flow of discharge of solids cake from the surface of the filter element 3 103325 opposite the filtration, and is provided with a bottom valve to remove solids cake. Said feed line is also available for washing liquid supply, even when washing is performed with ultrasonic cavitation.

According to the invention, the container in which the filter element is located may be vertical, and the flow to be filtered can be supplied tangentially and horizontally to the container wall. The reservoir may be cylindrical or alternatively conical, whereby a flow tangentially introduced into the reservoir will cause the liquid to exhibit a high degree of rotation and centrifugal force classification.

The filter element of a filter according to the invention may be a porous ceramic material such as alumina, silicon carbide or silicon nitride, or a porous sintered metal such as stainless steel, nickel or titanium. Such an element has a pore size in the range of 0.2 to 2 µm, which provides excellent resolution. The element is capable of separating colloidal particles such as clay particles and up to 15 bacteria from the liquid. Said ceramic materials are resistant to abrasion, high temperatures and corrosive conditions and have a long service life.

According to one embodiment of the invention, the surface of the ceramic filter element has a plurality, e.g. 3-5 pieces, of thin, glazed stripes that cut off the solid cake accumulating on the surface of the element so that it falls more easily into the bottom valve on the bottom.

As already mentioned, the invention also comprises a method for regenerating a filter element of a clarifying filter. In the method, the cylindrical filter element separating the solid from the liquid stream, which is located in a reservoir equipped with a flow connection for supplying the liquid stream and removing the filtrate and the solid cake, is periodically cleaned with a sequential ultrasonic cleaner. The method is characterized in that the ultrasonic cleaner forms a ring surrounding the filter element, which floats in the liquid in the reservoir, whereby, during cleaning, the annular cleaner is moved from the top down to the liquid surface.

The invention will now be described in more detail with reference to Figure 1 of the accompanying drawings, which shows a clarification filter according to the invention.

Figure 2 of the drawings relates to Example 1 below, showing the capacity (permeability) of a filter as a function of time.

4, 103325

The apparatus according to the drawing comprises a cylindrical container 1 into which fluid to be filtered can be pumped through valve 2. The container 1 has a cylindrical filter element 3 attached to the upper part of the container. The filter element 3 is made of sintered ceramics and has a pore size of between 0.2 and 2 µm. The filter element 3 separates 5 of the flow to be filtered into a filter cake accumulating on the surface of the solid element, while the filtrate that has passed the element is discharged into a filter tube 5 , which removes the cake that falls on the bottom of the container and is removed through the opened bottom valve 6. After washing, the washer fluid valve 8 and bottom valve 6 are closed and the feed and filtrate valves 2 and 4 are opened to continue filtration.

For the periodic regeneration of the filter element 3, a cylindrical ultrasonic vibrator 7 is provided around the cylindrical element 3, which supplies the ultrasonic generator 10 with a high frequency electric current supplied. The oscillator 7 provides ultrasonic cleaning of the element 3 on the surface of the element. Normally, the vibrator 7 floats in the liquid in the container 1 near the container lid. In order for the surface of the element 3 to be thoroughly cleaned, the container vent valve 9 and the drain valve 12 are opened while the supply valve 2 is closed at the same time. As the liquid 1 in the reservoir slowly drains, the annular ultrasonic vibrator 7 follows the surface until it reaches its lower position 11. During the ultrasonic cleaning, washing fluid fed through the valve 8 can be passed through the element 3 to facilitate the removal of clogging. The pressure of the washer fluid should be high enough, typically 0.5-5 bar.

25 The cleaning of the filter element 3 can be automated and repeated as required. The interval between purifications is adjustable and is typically 1-10 hours. As the filtration is continued after purging, the inlet valve 2 is opened, whereupon the reservoir 1 is filled with liquid and the air in the reservoir is discharged through the valve 9. Thereafter, the filtering data process continues as described above.

The solids in the liquid to be filtered, which can be separated by filtration according to the invention, may be inorganic or, in special cases, organic matter, preferably in an amount not exceeding 100 g / l and generally less than 10 g / l. Typically, 99% of the particles are up to 5 µm in size. The flow temperature is usually below 100 ° C, has a pH between 0.5 and 12 and a viscosity between 0.5 and 2.0 cp (mPa.s). Filtration 35 removes any particles larger than 1 µm from the liquid and the resulting filtrate is visibly clear.

5, 103325

Example 1

The liquid to be filtered was process water containing catalyst particles. The particles were vanadium and had a mean size of 1 µm.

The feed had a solids content of 100 ppm and a feed stream of 100 l / h. The filter-5 blade was sintered ceramic and had a pore size of 0.2 to 2 µm. The resulting filtrate had a solids content of 0.1 ppm. The capacity of the filter as a function of time was about 3 m / m h, and it was regenerated by ultrasound and backwash every two hours. The graph of Fig. 2 shows the capacity of the filter as a function of time.

Example 2

The paper mill's pigment-containing (kaolin, PCC, talc, CaCO 3) circulating water, with about 50% of the particles being less than 1 µm in size, was filtered by the clarification filter of Example 1. The filter element was regenerated 4 to 6 times per hour with short countercurrent rinsing bags and a few times daily with ultrasonic cleaning. The capacity achieved in the filtration was about 3 m3 / m2 h.

By filtration according to this example, the pigment that would otherwise be wasted and landfilled is recovered and used as a filler or coating for the paper. The pure filtrate can be recycled to process water, such as pump water.

20 Further Examples of Uses of the Invention

In brewing beer filtration, the ceramic membrane filter element has been found to clog about 1 hour after use. However, the element can be easily regenerated by chemical washing and ultrasonic cleaning according to the invention. The process requires two filter elements, one of which may be briefly washed.

A clarification filter according to the invention can be used to process the filtrates of separation processes performed with other types of filters. During the early stages of the filtration cycle, a large amount of solids, often the most valuable part of the product, is passed through the strip, barrier, chamber and pressure filters. This part goes into process cycle 30 and often runs into a thickener where they interfere with the operation of the thickener and where only part of it is recovered. However, with the clarification filter of the invention, the valuable product is recovered at the very beginning of the process, and the clear filtrate can be used for other purposes, such as the preparation of a flocculant. Further, washing the filter cake obtained with vacuum-strip filters leaves the filtrate with valuable solids, which pass through the entire process, ending up in the thickener. This solid can be recovered immediately after the vacuum strip filter with the automatic brightening filter according to the invention.

In the process of producing acids such as nitric acid, noble metals such as platinum are removed in the catalyst, which is desired to be recovered. The ceramic clarification filter of the invention is suitable for platinum recovery, despite highly acidic process conditions.

Claims (10)

1. Klarfilter innefattande et cylinderformat filterelement (3) i en behällare (1), color-coded canada genome behällarens hollow att de fasta ämnena i value-avantil account en Kaka pa elementets yta, strömningsrör (2, 4, 5, 6) för att leda flö-det som scall filterer i en behällare och för att avlägsna filtratet och den fasta äm-neskakan ur den, samt en ultraljudsrengörare (7) kopplad account en ultraljudsgenerator (10) för regenerering av filterelen, kännetecknen av attralraljud (7) bildats som en ring som omger filter element (3), och som i samband med ren-20 Göring kan flyttas jämte vätskeytan i behällaren (1) uppifrän nedät. A clarification filter, comprising a flow line (2, 4, 5, 5 6) of a flowable filter (2, 4, 5, 5 6) comprising a cylindrical filter element (3) located in a container (1) having a fluid flow to be filtered through a jacket to separate the solid in the liquid into a cake. for removing the filtrate and solids cake therefrom, and for regenerating the filter element of the ultrasonic cleaner (7) connected to the ultrasonic generator (10), characterized in that the ultrasonic cleaner (7) is formed as a ring surrounding the filter element (3) with the liquid surface 10 in the container (1) from top to bottom. 2. The filter enligt patentkrav 1, kännetecknat av att behällaren (1) i sin nedre del har en maszingsventil (12) för att sänkaiviv i i behällaren. Filter according to Claim 1, characterized in that the lower part of the container (1) has a drain valve (12) for lowering the liquid level in the container. 3. Filter enligt patentkrav 1 eller 2, kännetecknat av att avloppsledningen (5) för filtratet börjar vid behällarens (1) Belt bucket, att account behällaren (1) anslutits et ma-tarrör (8) för att alstra et flöde i en riktning motsatt account filtereringen som lösgör den fasta ämneskakan frän filterelementets (3) yta, och att behällaren är försedd med en. bottenventil (6), genomic expression of the fasta ämneskakka kan avlägsnas. 30 Filter according to Claim 1 or 2, characterized in that the filtrate outlet line (5) starts at the top of the container (1), in that a supply line (8) is connected to the container (1) to produce a flow opposite to the filtration detachable from the surface of the solid cake filter element (3). and that the container is provided with a bottom valve (6) through which the solids cake can be removed. 4. Filter enligt face av föregäende patentkrav, kännetecknat av att behällaren (1) vertically och att tillförselröret för flödet som scall filtereras matar flödet i behällaren tangentialt. Filter according to one of the preceding claims, characterized in that the container (1) is vertical and that the flow inlet to be filtered supplies the flow tangentially to the container. 5. Filter enligt patentkrav 4, kännetecknat av att behällaren (1) har en konisk form. 9 103325 Filter according to claim 4, characterized in that the container (I) has the shape of a Carti. 6. Filter enligt face av foregaende patch screw, bending nozzle filter element (3) for dusting ceramic material, alumina alumina, shells muller nitrile, muller sintered metal, matt rostrite ställ, nickel eller Titan. Filter according to one of the preceding claims, characterized in that the filter element (3) is made of a porous ceramic material such as alumina, silicon carbide or silicon nitride, or a porous sintered metal such as stainless steel, nickel or titanium. Filter according to claim 6, characterized in that the surface of the ceramic filter element (3) has glazed, painted stripes to cut off and facilitate removal of the solid cake accumulating on the surface of the element. 7. Filter according to claim 6, in the form of a filter element (3) firms glasade, a memory path for the att bryta den fasta ämneskakan som samatats head element yta och för att underlätta avlägsnandet av den. 7 103325 8. Förfarande för regenerering av filterelementet (3) i klarfilter, colors det cy-10 linderformade filterelementet som avskiljer fasta ämnen frän vätskeflödet och hærter (1) försedd med strömningsrör (2, 4, 5, 6) som beh för inmatning och avlägsnande av filterat och fasta ämnen, rørk peri-odvis med en ultraljudsrengörare (7) anordnad i behällaren, kännetecknat av att-raljudsrengöraren (7) bildar en ring som omger filterelement i behällaren (1), varvid den ringformade rengöraren vid rengöringen flyttas uppifrän nedte i behällaren jämte vätskeytan. A method for regenerating a filter element (3) of a clarifying filter, wherein the method comprises providing a cylindrical filter element separating a solid from a liquid stream, which is disposed in a container (2, 4, 5, 6) with flow connections (2, 4, 5, 6) for supplying liquid flow and filtrate and solids. intermittently cleaned with an ultrasonic cleaner (7) provided in the container, characterized in that the ultrasonic cleaner (7) forms a ring surrounding the filter element (3), which floats in the liquid in the container (1). 9. Förfarande enligt patentkrav 8, kännetecknat av att vätskeytan sänks via en: numningsventil (12) i behällarens (1) nedre del. 20 Method according to claim 8, characterized in that the liquid level is discharged through a drain valve (12) located at the bottom of the container (1). Method according to Claim 8 or 9, characterized in that, during the ultrasonic cleaning, liquid is introduced into the container (1) so that the liquid flow passes through the filter element (3) in the opposite direction to the filtration. 10. Förfarande enligt patentkrav 8 eller 9, kännetecknat av att under ultraljuds-rengöringen leds vätska i behällaren (1) saves the viscous strömmar genome filter element (3) i en riktning motsatt mot filtreringen.