Backflush filterelement

Abstract: Filterelement, formed by a supporting body with a filtration part and a connecting part extending therefrom, in which the filtration part has the form of a flat ellipse or a flat rhomb, from which the connecting part gradually extends to a rounder shape, while over the supporting body a filterbag has been applied which at the open end has been fastened onto the connecting part by means of a clamp device.

Description: The invention relates to a backflush filter element, in which the filter element is intended to be installed in a filter tank standing on or depending from a filter plate or a mainfold, and in which the filter element is formed by a supporting body with a filtration part and a connecting part extending therefrom, through which the filtrate may be discharged, while over this supporting body a filter medium has been applied. The invention relates more in particular to a backflush filter element, in which the ratio between the filtration surface per meter of length of the filter element and the section of the filtrate discharge is between 285 and 680, and the filtrate surface is between the 0,07 m2 and 0,46 m2. Such a backflush filter element is known in the shape of a filter candle. This filter candle has a cylindrical shape, which has the disadvantage, that in the so-called candle filter, in which a number of filter candles have been installed in the filter tank, the ratio between the complete filtering surface of the joint candles and the volume of the filter tank is low. Reference is also made to GB-A-21595 which teaches candle filters with an ellipse or rhomb cross section The filter element according to the invention is defined in claim 1. The ellipse or rhomb shape of the backflush filter element, as compared to the cylindrical shape of the filter candle, a substantially larger filtration surface can be obtained per unit of volume of the filter tank. So, by using the backflush filter element according to the invention, 57 % more filtration surface per unit of the volume of the filter tank can be obtained as compared to the filter candle. Besides in that the free space between the elements remains the same, the cake space by using the backflush filter element according to the invention may somewhat increase as compared to the filter candle. According to a further feature of the filter element according to the invention, the largest ratio of thickness to width in the horizontal section of the filtration part is between the 10 and 25 %, and this ratio preferably has a value of 17 %. In an embodiment of the filter element according to the invention, the filter medium has the shape of a filter bag of filter cloth, or of filter gauze of metal or synthetic material, or of sintered metal fibres or of filter membrane material. Preferably this filter medium is deformable, making a dry cake discharge possible. According to the invented filter element, the outer peripheries of the filtration part and the connecting part of the supporting body are substantially equal to one another, such, that a filter bag, which has been applied fitly over the filtration part, and which has been sealed off rectilinearly at the lower side and being rectangular in downfolded state, may at its open end, while free of folds, be fastened onto the rounder connecting part by a clamp device, such as a clamp band, and thereby the filter medium evenly loading underneath the clamp device. The filter element according to the invention may be set up in a manner, known in itself, of a supporting body with supporting gauze, and over which the actual filter medium has been applied. The supporting body may thereby be made out of various materials, such as synthetic material or metal, and in various ways, such as a casting or moulding. In an embodiment of the invented filter element, the connecting part and the filtration part of the supporting body are made of metal plate, this metal plate at the filtration part being provided with perforations and a cover of support gauze for the discharge of the filtrate up to within the support body. In an embodiment of the invented filter element an raising pipe for the filtrate discharge has been installed inside the supporting body and which may be flattened within the filtration part of the supporting body. The invention will now be further explained with reference to the drawing of an embodiment by way of example. Fig. 1 is a side view of the filter element according to the invention. Fig. 2 is partly a top view, and partly a section of the filter element according to Fig. 1. Fig. 3 is a perspective view of an embodiment of the invented filter element in partly worked open state. Fig. 4 is an arrangement of filter candles, such as this may take place in a filter tank. Fig. 5 is an arrangement of the filter elements according to the invention in a filter tank. As can be seen in Fig. 1 and Fig. 2, the filtration part 1 of the element has a substantially rhomb-shaped section, and in which the flattened filtrate discharge pipe 2 has been taken up. The flat rhomb-shape extends upwardly to a rounder periphery shape, in such a way, that a filter bag 3, which has been applied over the rhomb-shape of the element, fits onto the rounder periphery shape and which may be sealed off thereon by means of a clamp band 4. In the centre of the top closure extends the raising pipe 2 for the filtrate discharge. As shown in Fig. 3, the filter element is formed by a supporting body with a filtration part 5 of steel plate with perforations 7, over which supporting gauze 8 has been applied and thereover the bag-shaped filter medium 3. Of the filtration part 5, of which the section has the shape of a flat ellipse, the opposed end portions 9 are bent over towards one another and are connected to one another by spot weldings. From the filtration part 5 the connecting part 6 extends gradually widening to a rounder shape, and on which the filter bag 3, which is sealed rectilinearly at its lower side, has been fastened with a clamp band 4. Inside the supporting body again a raising pipe 4 for the filtrate discharge has been mounted. With reference to Fig. 3 and Fig. 4 the following comparison can be made of the cricket bat-shaped element, i.e. the filter element according to the invention, and the filter candle. a) Filter candle: 0 = 51 mm (2") 1 = 1524 mm (60") stitch = 91 mm triangle Filter surface per candle - 0,244 m2 Surface section per candle - 2043 mm2 Surface section space per candle - 7172 mm2 Surface section free space per candle - 5129 mm2 b) Cricket element: section = 110 x 18,5 mm. 1 = 1524 mm stitch = 115 x 57.5 mm. Filter surface per element -0,354 mm2 (plus 45%) Surface section per element -1452 mm2. Surface section space per element -6613 mm 2 (- 8%) Surface section free space per element -5161 mm2 Result: 1. 57 % more filter surface / unit of volume of the filter casing. 2. Free space around the elements has remained the same. 3. Cake room is 44 mm instead of 40 mm.

Claims: A backflush filter element, which is intended to be installed in a filter tank standing on or depending from a filter plate or manifold, formed by a supporting body with a filtration part and a connecting part extending therefrom, through which the filtrate may be discharged, while over this supporting body a filter medium has been applied, whereby the section of the filtration part has the shape of a flat ellipse or rhomb, characterised in that the connecting part gradually extends from the filtration part widening to a rounder shape, while the outer peripheries of the filtration part and the connecting part of the supporting body are substantially equal to one another. Backflush filter element according to claim 1, characterized in that in the section of the filtration part the largest ratio of thickness to width lies between the 10 and 25%, more in particular has a value of 17%. Backflush filter element according to claim 1 or 2, characterized in that the filter medium has the shape of a filter bag of filter cloth, of filter gauze of metal or synthetic material, of sintered metal fibres or filter membrane material. Filter element according to claim 1, 2 or 3, characterized in that the connecting part consists of metal plate. Filter element according to any of the preceding claims, characterized in that the filtration part of the supporting body has been formed from perforated metal plate with there over supporting gauze for the discharge of the filtrate up to within the supporting body. Backflush filter element according to one of the preceding claims, characterized in that the opposed end portions of the metal plate of the filtration part are bent over towards one another and are connected to one another. Backflush filter element according to one of the preceding claims, characterized in that within the supporting body a raising pipe for the filtrate discharge is mounted. Backflush filter element according to claim 7, characterized in that inside the filtration part the raising pipe has been flattened.

Inventors: PLAISIER LEENDERT, PLAISIER, LEENDERT
Applicants: AMAFILTER BV
Application year: 1989
Main classification: B01D29
IPC codes: B01D29, B01D46, B01D63