|Title of Invention||
"FILTER FOR TREATMENT OF A FLUID AND PROCEDURE FOR THE BACKWASHING OF A FILTER THEREOF"
|Abstract||Disclosed is a container (1) for receiving a fluidized bed, comprising a turbulence chamber for receiving a medium that is to be vortexed, and a cushioning space (7) which is disposed below the turbulence chamber and is provided with an inlet (6) for a fluid that vortexes the medium. Said inlet guides the fluid into the cushioning space in such a way that a circular, upward-directed current is generated. Also disclosed are methods for backwashing a filter used for treating water.|
|Full Text||"Filter, as well as a procedure for backwashing of a filter, especially serving for the treatment of water"
The invention concerns a filter for the treatment of water as well as a procedure for the backwashing of a filter. This procedure can specifically be used for the backwashing of a filter serving for the treatment of water.
From the WO 02/11878 A1, the US 6 331 283 B1 and the DE-AS-1208 736 fluid bed reactors are known in which a medium consisting of single bodies in the whirl chamber is flown through with gas from bottom to top. The medium in the container serves as reaction medium and / or catalyst. The creation of a fluid bed therefore is the normal operating condition of the reactor.
The EP 0088 638 A2 relates to a fluid bed reactor; gas as a fluid is fed into the reactor by a gas distribution system.
The US 4 869 815 relates to a fluid bed reactor with a lower chamber that is not free from reaction bodies. Also, the fluid cannot flow through freely and there is no separation from the area where free flowing single bodies are found (US 4 869 815: reaction bodies / for the present invention: filter medium). It would be disadvantageous to use the known fluid bed reactor as a water filter because with a backwashing of the filter no fluidisation of the filter bed would be possible. According to the US 4 869 815 the lower layer is not conceived as a fixed bed for fluidisation. Besides, solid substances which settle in this lower layer and / or in this lower fixed bed during the filtering process cannot be washed out later during a filter backwashing because of a non-existing fluidisation
The WO 00/76655 A1 concerns a fluid bed reactor filled with grainy material and that like the fluid bed reactor as previously mentioned ace. to the US 4 869 815 has no separating bottom separating an underdrain chamber without solid bodies from the upper part of the container. According to the WO 00/76655 it would be disadvantageous to use the known filter bed reactors as water filter. The normal flow direction opposing the direction of the backwashing flow which consequently
works from top to bottom will carry out the filter material through a provided inlet gap and it will be rinsed out from the container.
The flow conditions of gases differ substantially from those of fluids. The fluid stream can be regarded as pipe flow for an inlet formed as a line section as well as within the container itself. As a non-compressible medium water has a linear pressure decrease for pipe flows whereas gas as a compressible medium has a non-linear pressure decrease for pipe flows. Furthermore, the speed is constant for water pipe flows, whereas the speed for gas pipe flows is not constant. Consequently, calculation of water pipe flows is done ace. to the Bernoulli equation, that of gas pipe flows ace. to different pressure decrease equations.
Other than the previously mentioned technique the present invention concerns a filter for the treatment of water which is flown through by, i.e. water. The filter medium can be present as irregularly shaped , natural granulates, e.g. quartz sand or activated carbon and / or anthracite. But industrially produced bodies for example in ring form can be used as well. The fluid used for the flow process whirls the individual bodies thus using at an optimum reactive surfaces of the medium. For that purpose a most even shape of the fluid bed is required.
Filters, known from practical use receive the fluid by inflow in the centre of the lower wall of the underdrain chamber so that a vertical flow of the fluid is directed upwards and hits against the separating bottom which separates the underdrain chamber from the whirl chamber. In order to achieve an even distribution of this central main stream covering the entire cross section of the filter chamber an additional, so-called supporting layer is often provided above the separating bottom between underdrain chamber and whirl chamber which can be filled with coarse, grained material which leads to an even shape of the flow bed.
A substantial flow resistance is created for the fluid before it gets to the whirl chamber. To overcome this flow resistance adequate energy has to be added to the fluid, i.e. pumping capacity to guarantee the required whirling of the medium in the whirl chamber. For example in the field of drinking water treatment where a backwashing of the filter medium takes place ace. to the fluid bed procedure the
required energy can only be provided by quite complex and expensive constructions
Purpose of this invention is the creation of a filter allowing the cleaning of the filter medium with as little resistance as possible and an even distribution of the fluid thus resulting in an even shape of the fluid bed
A filter with the characteristics as described in patent claim 1 and a procedure with the steps as described in patent claim 9 fulfil these requirements The use of such filters guarantees an advantageous application ace to the procedure as described in patent claim 10
The invention suggests in other words, for the creation of the fluid bed in the filter, to have the fluid flow as a circular, upwards directed stream which then spreads evenly under a so-called "filter bottom", i e a separating bottom and which separates the underdrain chamber from the filter chamber respectively whirl chamber The circular flow leads to a favourable distribution of the fluid in the underdrain chamber, additional layers , known from practical use as so-called supporting layers - in the shape of coarse grains, can be spared These supporting layers shall serve to create an even shape of the upwards directed flow between underdrain chamber and whirl chamber
The filter medium in form of a multitude of individual bodies is located above the separating bottom In normal operating conditions of the filter, i e during filtration the filter medium is a fixed bed Only from time to time, for the cleaning of the filter medium in form of filter backwashing the creation of a fluid bed can be considered For this purpose the filter is backwashed in opposite flow direction so that the individual bodies of the filter medium are being fluidised and solid substances which are deposited in the underdrain chamber are rinsed out of the filter Furthermore, solid substances attached to the individual bodies of the filter medium are being detached from those
To achieve the circular, upwards directed flow the inlet is connected off centre to the underdrain chamber in which the inlet is formed as a line section, e g as a tube end and approx tangentially aligned so that by the design and alignment of
this section the direction of the flow is preset. Thus a circular flow without any hindering constructional elements is easily achieved.
According to the suggestion the separating bottom restricting the underdrain chamber upwards has openings that are arranged in a circular way and which are aligned "approx. tangential" rather tangential than radial. A lesser pressure loss is the result for this separating bottom and for the whirling of the fluid bed a comparatively low flow rate is required. A reduced consumption of the fluid is the result. For a filter backwashing ace. to the principle of gravity where the fluid comes from a storage container the storage capacity of the container can be quite limited.
Preferably, the sideward introduction of the fluid can favour the creation of a circular flow by connecting the inflow approx. tangentially to the underdrain chamber. "Approx. tangentially" means that the fluid must not flow exactly tangentially with mathematical exactness. The design of the inlet should allow the flow not to be directed radial towards the centre of the underdrain chamber which would result in unwanted whirls, the aim is a circular flow, more tangential than radial. The flow could also be bent with a slight twist by introducing it through a bent inlet.
It might be an advantage to support the upwards directed flow by adjusting the inlet for example in form of an upward pointing tube.
The design of a flow restriction above the inflow for the ascending fluid could be an advantage so that the inflowing fluid does not rise substantially higher laterally than in the middle of the underdrain chamber. Thus an even distribution of the fluid as well as an even development of the fluid bed are achieved. Therefore an inward protrusion of the wall of the underdrain chamber above the inflow could be advantageous.
This can be achieved by a groove moulded into the wall or a flow guiding device welded to the wall thus forming an inwardly protruding part of the wall. Or else, it could be an underdrain chamber with an upwardly decreasing cross section, or a underdrain chamber having the shape of a cone that is upwardly tapering. The
walls of the underdrain chamber could either be straight, convex or concave. The course should be selected in accordance with the fluid to be used and the other operating conditions of the container.
Such a separating bottom favours the development of an even fluid bed so that the before mentioned supporting layer or other supporting devices are not needed. That way the height of the container is reduced. For the previously mentioned filter backwashing according to the gravity principle the reduction of the height of the storage container is possible. In addition to the comparatively small container volumes the static requirements of the storage container are lower allowing a less expensive production.
Plus! the washing rate for the effective backwashing is decreased, a smaller water quantity is
required thus resulting in smaller volume of the storage container.
The use of carbon filter media such as the mentioned anthracite, in addition to the advantage of
low specific weight, have high hygienic advantageous especially with the use of a filter in the
filed of drinking water and the food industry.
This suggestion prefers a procedure for the creation of a fluid bed leading the fluid in form of a
circular, upwards directed stream into the medium. This procedure can be used advantageously
for the backwashing of a filer as described by the preceding examples, in case of a filter serving
for the treatment of water.
In accordance with the present invention it relates to a Filter for the treatment of a fluid, with a filter housing which is, as a container for accommodation a fluid bed, designed as follows: with a whirl chamber which as a filter space contains a filter medium consisting of numerous free flowing single bodies; with an inlet (6) for a fluid whirling the filter medium, said intake being connected off centre to the underdrain chamber; the inlet (6) being formed as line section and being aligned approximately tangentially; so that the inlet (6) leads the fluid into the underdram chamber as a circular upwards directed stream; the filter being operable in a filtration- mode in which the filter medium is present as a fixed bed, characterized in that the filter for the treatment of water is being operable as well in a second "backwashmg"-mode, in which the filter medium is flown through as a fluid bed, and that the filter comprises an underdrain chamber located beneath the whirl chamber; and that the filter comprises a separating bottom (9) provided between the whirl chamber and the underdrain chamber, the separating bottom (9) having openings) 10) which are either arranged in an approximately circular manner and which are oblong, with their longitudinal axes being approximately tangentially aligned, or which extend in an essential concentric manner to the centre of the separating bottom(9).
The following schematic drawings describe the design examples of the invention. The following
Fig. 1 A side view of the underdrain chamber of a container
Fig. 2 A top view of a part of the container of fig 1, some detils however are left out
Fig. 3 A view similar to Fig. 2 for another design
Fig. 4 A view similar to Fig 1 showing another design
Fig. 5 A top view of a first separating bottom which restricts the underdrain chamber towards
the upper side
Fig. 6 A view similar to fig 5 as a top view of a second separating bottom
In fig. 1 a lower part of the container is described in total which forms the lower part of an in
total substantially higher container. Such a container ran be designed as a fluid bed-reactor or
as filter for drinking water where the lower part of container 1 encloses the underdrain chamber
which is placed beneath the whirl chamber and/or filter chamber of such a container. This
whirl chamber can be built as a cylinder so that the lower part of container 1 has a
cross section. It stand by means of bases 2, on a base plate 3 and has a flange 4 on its upper end for connection to the construction unit of the whirl chamber, as well as an outlet tube 5 through which the entire container can be emptied.
The lower part of container 1 has an inlet 6 in form of a tube section which connects sidewards to the wall 7 of the lower part of container 1. As is shown in Fig. 2 the inlet 6 is connected tangentially to the wall 7 which has a round cross section and encloses the underdrain chamber of the container.
Fig. 2 shows that the underdrain chamber has a free cross section within the wall 7, Fig. 3 shows a flow guiding metal plate 8 which has the shape of a crescent moon and welded to the remaining wall 7 thus forming an inwardly protruding part of this wall. The flow guiding plate 8 is arranged above the inlet 6 so that the fluid flowing into the underdrain chamber does not mount on the inner side of the wall 7.
Fig. 4 shows as an alternative to Fig. 3 however presented similar to Fig. 1 that such a guidance of the inflowing fluid can be achieved by an upwardly decreasing cross section of the underdrain chamber. The wall 7 of this design has the shape of a cone and therefore the fluid flowing tangentially into the underdrain chamber as shown in Fig. 1 and 2 does not mount radial higher at the outside than in the centre of the underdrain chamber.
A resistance poor entry of the circular flowing fluid is achieved by a separating bottom 9 as shown in Fig. 5 which restricts the whirl chamber and / or the filter area towards the lower part and the underdrain chamber. For this separating bottom 9 numerous oblong openings are provided; they are formed as slits and arranged concentrically around the centre of the separating bottom. The openings 10 are bent, they are not only concentrically arranged but also have a concentric bent course. This shows what is meant by an "approx. tangential" alignment and arrangement of these openings 10 through which a resistance poor entry of the fluid from the underdrain chamber into the whirl chamber and / or filter is guaranteed.
A separating bottom 9 as an alternative for Fig 5 is shown in Fig 6 Here no closed plate is provided as separating bottom 9, but according to Fig 6 the separating bottom 9 rather consists of individual concentrically arranged rings where the gaps between the rings form the openings 10 The individual rings can be connected with each other or have only spacers and lie on a supporting frame in the container Fig 6 does not show the arrangement of the rings in several segments The border line of the individual segments can be radial so that segments like cake pieces can be formed However another possibility is to completely form individual rings of smaller diameters and to only divide the rings with larger diameters which are heavier in individual arc shaped segments which are now easier to transport and to handle than the complete individual ring Fig 6 also shows the separating bottom 9 with an advantageously low resistance around the circular upwards directed stream to enter through the separating bottom 9
1. Filter for the treatment of a fluid, with a filter housing which is, as a container for accommodation a fluid bed, designed as follows: with a whirl chamber which as a filter space contains a filter medium consisting of numerous free flowing single bodies; with an inlet (6) for a fluid whirling the filter medium, said intake being connected off centre to the underdrain chamber; the inlet (6) being formed as line section and being aligned approximately tangentially; so that the inlet (6) leads the fluid into the underdrain chamber as a circular upwards directed stream; the filter being operable in a filtration- mode in which the filter medium is present as a fixed bed, characterized in that the filter for the treatment of water is being operable as well in a second "backwashing"-mode, in which the filter medium is flown through as a fluid bed, and that the filter comprises an underdrain chamber located beneath the whirl chamber; and that the filter comprises a separating bottom (9) provided between the whirl chamber and the underdrain chamber, the separating bottom (9) having openings(l0) which are either arranged in an approximately circular manner and which are oblong, with their longitudinal axes being approximately tangentially aligned, or which extend in an essential concentric manner to the centre of the separating bottom(9).
2. Filter as claimed in claim 1, wherein the inlet (6) is directed upwards.
3. Filter as claimed in claim 1 or 2, wherein above the inlet (6) the wall of the underdrain chamber protrudes inwardly.
4. Filter as claimed in claim 3, with an inwardly protruding flow guiding plate(8).
5. Filter as claimed in claim 3 with a cross section of the underdrain chamber decreasing upwards above the inlet (6).
6. Filter as claimed in claim 5 with a truncated-cone-shaped underdrain chamber.
7. Filter as claimed in one of the previous claims wherein the separating bottom (9) consists of several segments.
8. Filter as claimed in one of the previous claims with a filter medium, with a low specific weight such as lava rock, pumice rock, blowing clay granulates or carbon containing material such as anthracite.
9. Procedure for the backwashing of a filter as claimed in one of the previous
claims, the filter medium consisting of numerous free flowing single
bodies, and wherein for creating a fluid bed a fluid is led from bottom to
top through the filter medium, in a way that the single bodies of the
medium are whirled and the medium is lluidized, and wherein the fluid is
led into the medium in form of a circular, upwards directed flow.
10. Filter for the treatment of water substantially as herein described with reference to the foregoing description and the accompanying drawings.
11. Procedure for the backwashing of a filter substantially as herein described with reference to the foregoing description and the accompanying drawings.
|Indian Patent Application Number||3106/DELNP/2005|
|PG Journal Number||01/2011|
|Date of Filing||12-Jul-2005|
|Name of Patentee||BECKE, CHRISTIAN|
|Applicant Address||STEHRSTRASSE 51, 48565 STEINFURT, GERMANY|
|PCT International Classification Number||B01D 24/12|
|PCT International Application Number||PCT/DE2003/004088|
|PCT International Filing date||2003-12-11|