DE202004011839U1 - Fluid filtration unit, comprises a housing with supply and removal channels, back flushing channels, and a sieve carrier with filter elements - Google Patents

Abstract

An arrangement for filtering a fluid, especially a liquefied plastic, comprises a housing (1) with a supply channel (2), a removal channel (3) and back flushing channels (9,10). A sieve carrier (4,4a) is arranged laterally with respect to the flow direction and contains at least one filter element (5,6) in a sieve chamber (7,8). The carrier can be connected to the channels. A piston is located in a channel section that leads from the sieve chamber to the removal channel, and moves the clean material to the relevant flushing channel when the sieve carrier is in the back flushing position. At least two filter elements are located in the sieve chambers, and there are at least two channel sections and two back flushing channels. A pressure generator is located near the supply channels, and produces constant pressure.

Description

The Innovation relates to a device for filtering a Fluids, especially a liquefied one Plastic with a housing with a feed channel, a discharge channel and backwash channel, being in the flow path of the fluid in a direction transverse to the flow movably mounted portafilter two filter elements arranged in corresponding sieve spaces and with the Feed channel and the discharge channel can be connected according to the preamble of claim 1.

Such devices for filtering a fluid are e.g. B. from the DE 35 27 173 C1 known. In these known devices, the arrangement is such that two sieve carriers are assigned to one another in parallel, so that the supply of the device connected to the filter device does not have to be interrupted during the washing of the sieve spaces of the one sieve carrier. The contamination-free melt used for the rinsing purposes is removed downstream of the portafilter just in the operating position. Here, the backwash effect is essentially determined by the flow rate of the backwash stream, which in turn depends on the back pressure of the downstream device connected to the filter device. This back pressure is generally relatively low and cannot be influenced in any way. This results in poor or, in the case of larger screen areas in particular, only partial rinsing of the dirty screen. In addition, there is a loss of mass in the main flow at the time of backwashing, the greater the longer the time required for sufficient washing of the sieve space or of the sieve of the sieve carrier currently in the backwash position.

Out WO 92/16 351 A1 is a filtering device for those to be cleaned Fluids have become known that work with a cylinder Accumulator piston works. To make the rinsing process quick, effective and over the area of the sieve evenly and an additional one Avoiding loss of mass in the main flow during backwashing is in the filter holder body Storage room available, which in normal operation with cleaned melt filled is and in which a storage piston is displaceable, with which in the backwash position of the portafilter body melt located in the storage space in the backwashing direction through the sieve and is pressed into the backwash channel. The use of an additional Cylinder space and accumulator piston is complex and always hides the danger in itself that in the Plastic residues from the accumulator piston remain, which crack and can cause difficulties.

at this known device, it is necessary that the im Portafilter body available Storage space, which is acted upon by the storage piston, with cleaned Melt filled becomes. At the time of filling this pantry occurs naturally a pressure loss at the discharge channel or in the filter device connected implement or tool so that the process pressure is not constant.

From the DE 17 88 037 U1 A device for separating liquid and solid-containing mixtures has become known, in which the liquid containing solid is passed through a sieve, at the same time a storage piston being moved back. A drain line connects to the space of the storage piston, through which the cleaned liquid is discharged. The connection between the storage piston and the discharge line is equipped with a check valve which only opens when the storage piston generates a corresponding pressure in the discharge line. At the same time, when the storage piston is moved, the cleaned liquid can also be pressed through the sieve again in order to clean it of accumulating solid particles. Such a device cannot be used for liquefied plastic, in particular because the check valve provided there clogs very quickly in the drainage channel and would become unusable, with material remaining in the space between the check valve and the storage piston, which degrades, i.e. here, too, there are dead zones that are absolutely necessary must be avoided when processing liquid plastic.

The The task of innovation is to propose a device, where the backwash effect can be significantly improved, but at the same time also the loss of mass in the main stream at the time of backwashing, which is avoided in the Channel-arranged displacement pistons always washed by material will, so here no material can break down and the pressure at the portafilter housing outlet can be kept constant.

This The task underlying the innovation is through the teaching of the Device defining claim 1 solved.

According to this teaching, it is proposed that so-called displacement pistons are assigned to the subchannels leading from the screen space (s) to the discharge channel. These subchannels are straight and relatively long, and a displacer opens into these subchannels, which in the backwash position supplies the dirt-free material in this subchannel to the back of the filter element, again with a pressure that is significantly higher than that Pressure that is normally on the pure screen side in the pro Production position of the portafilter prevails, with an additional pressure generator in the supply channel ensuring a constant process pressure, even when the displacement piston is withdrawn.

Farther The innovation provides that the portafilter is moved in this way can be that Filter elements from the screening rooms can be removed.

Preferably conclude to the filter holder receiving housing connection plates on, causing the displacement pistons easier to replace and the channels are easier to manufacture.

The or the displacement pistons can hydraulic, mechanical, e.g. B. about Toggle lever systems, racks, etc.

in the Feed channel can be a flow divider and a flow guide in the discharge channel be housed in order to create good flow conditions.

The Working pressure of the displacement piston or pistons can be preset.

The device according to the innovation has the big one Advantage that the Backwashing takes place immediately, as soon as there is a corresponding need message and in the connected implement or tool there is a constant process pressure.

On embodiment the innovation is explained below with reference to the drawings. The painting show in

1 a device with two displacement pistons and in

2 a section through the portafilter according to a device 1 ,

In 1 and 2 is a portafilter 4 receiving housing 1 shown, being in the housing 1 a feed channel 2 and a discharge channel 3 is arranged and on the downstream side of the portafilter 4 a connection plate 18 followed.

In the portafilter 4 are as sieves 5 . 6 trained filter elements in sieve chambers 7 . 8th provided, it should be noted that the term "sieve carrier" is used in conjunction with the term "sieves", but it should be pointed out that the term "sieve" also refers to a wide variety of sieves, filters and other retention devices for soiling.

In the feed channel 2 is a flow divider 19 recognizable ( 2 ) and in front of the feed channel 2 is a pressure generator 24 arranged, e.g. B. a pump.

Furthermore are in the housing 1 Rückspülkanäle 9 and 10 provided that lead to the atmosphere.

subchannels 20 . 21 are straight and take displacement pistons 22 and 23 on that at the in 1 shown arrangement can be operated via a mechanical plunger device. With the arrangement according to 1 is a connection plate 18 recognizable, causing the displacement piston 22 . 23 in the event of damage or the like, can be replaced more easily.

The 2 shows a section in the longitudinal axis of the portafilter 4 , and here are the sieves 5 and 6 and the screening rooms 7 and 8th recognizable, as well as the subchannels 20 and 21 ,

Returning to the representation in 1 it can be seen that the displacement piston 23 is in a position in which the sieve 5 in the portafilter 4 the connection between the feed channel 2 and the discharge channel 3 manufactures, ie the device is in production position.

The displacement piston 22 on the other hand drove down and it is also in the portafilter 4a sieve 6 by moving the portafilter 4a in connection with the backwash channel 9 , and in this position the displacement piston has 22 that in the subchannel assigned to it 20 located clean material with adjustable, relatively large pressure on the clean sieve side and thus the dirt sieve side of the in the portafilter 4a sieve 6 freed from dirt.

With the arrangement according to 1 and 2 It is particularly important to note that the end face of the displacement piston 22 respectively. 23 always flows around the material so that there are no dead zones in which material can degrade.

The additional in the area of the feed channel 2 arranged pressure generator 24 , preferably a pump, but other pressure generators can also be used, which has the effect that irrespective of the backwashing, that is to say irrespective of whether both channels 20 and 21 are in use or only one channel, and regardless of where the displacer 22 respectively. 23 in the channel 20 respectively. 21 stands, the process pressure in the area of the discharge channel 3 is always kept the same. This is for the at the discharge channel 3 connected implement or tool of great importance.

Claims (9)

Device for filtering a fluid, in particular a liquefied plastic, with a housing ( 1 ), with a feed channel ( 2 ), a discharge channel ( 3 ) and backwash channels ( 9 . 10 ), whereby in the flow path of the fluid in a sieve carrier which is slidably mounted transversely to the flow direction ( 4 . 4a ) at least one filter element ( 5 . 6 ) in an appropriate screening room ( 7 . 8th ) arranged and with the feed channel ( 2 ) and the discharge channel ( 3 ) can be connected, characterized in that a) that in one of the screen space ( 7 ) to the discharge channel ( 3 ) leading subchannel ( 20 ) a displacement piston ( 22 ) that can be inserted in the subchannel ( 20 ) dirt-free mass to the assigned backwash channel ( 9 ) when the portafilter ( 4 ) is in the backwash position, b) that at least two filter elements ( 5 . 6 ) in appropriate screening rooms ( 7 . 8th ) and at least two displacement pistons ( 22 . 23 ) are provided, c) that at least two subchannels ( 20 . 21 ) and at least two backwash channels ( 9 . 10 ) are provided and d) in the area of the feed channel ( 2 ) a pressure generator is arranged which has a constant process pressure at the discharge duct ( 3 ) and the downstream equipment during the production phase. Device according to claim 1, characterized in that the pressure generator ( 24 ) is designed as a pump. Device according to claim 1 or 2, characterized in that the filter holder ( 4 ) can be moved so that the filter elements ( 5 . 6 ) from their screening rooms ( 7 . 8th ) can be removed. Apparatus according to claim 1 or 2, characterized in that the filter holder ( 4 . 4a ) housing ( 1 ) connectable connection plates ( 18 ). Device according to one or more of the preceding claims, characterized in that the displacement piston or pistons ( 22 . 23 ) are hydraulically actuated. Device according to one or more of the preceding claims 1 to 4, characterized in that the displacement piston or pistons ( 22 . 23 ) can be operated mechanically. Device according to one or more of the preceding claims, characterized in that in the feed channel ( 2 ) a flow divider ( 19 ) in front of the two screening rooms ( 7 . 8th ) is arranged. Device according to one or more of the preceding claims, characterized in that in the discharge channel ( 3 ) a flow guide ( 19 ) is arranged. Device according to claim 1, characterized in that the working pressure for the displacement pistons ( 22 . 23 ) is adjustable.