FR2485385A1 - BED FILTER OF GRANULAR MATERIALS FOR THE TREATMENT OF WATER, ESPECIALLY SEA WATER AND CORROSIVE LIQUIDS - Google Patents

Abstract

BED FILTER OF GRANULAR MATERIALS COMPRISING MEANS PLACED BELOW THE BED OF GRANULAR MATERIALS FOR THE RECOVERY OF FILTERED WATER AND FOR THE SIMULTANEOUS INTRODUCTION OF AIR AND WASHING WATER IN ORDER TO PROVIDE A BACKWASH WASHING OF THE BED OF GRANULAR MATERIALS, THESE MEANS INCLUDING A COLLECTOR PROVIDED WITH RAMIFICATIONS AND BASED ON A SURFACE OF WATERPROOF SUPPORT, CHARACTERIZED IN THAT THIS COLLECTOR 8 IS SINGLE AND HAS A PIPELINE 7 FOR THE INTAKE OF WASHING AIR AND A PIPELINE 6 FOR THE OUTPUT OF THE TREATED WATER AND THE INLET OF THE WASHING WATER, AND IN THAT THE COLLECTOR 8 AND ITS BRANCHES 9 CARRY THEIR UPPER PART OF WELLS 10 AND 11, OF KNOWN TYPE, LAID DOWN SO THAT THE SLOTS PROVIDED FOR THEIR LOWER PART ARE ALL AT THE SAME LEVEL INSIDE THE COLLECTOR AND ITS BRANCHES.

Description

Bed filter of granular materials.

  The present invention relates to bed filters of

granular materials, used in water treatment of all types

ture, and comprising one or more layers of granular materials

filter res, arranged in an enclosure, a water inlet to be treated above the bed of filter materials, as well as a treated water intake and a washing device arranged at the base

filter material.

  These granular material bed filters are in the form of either an open enclosure made of concrete for example, or a closed enclosure, metallic or made of plastic. The proper functioning of these filters depends, among other things, on the perfect distribution across the filtering mass of the water to be filtered and the washing fluids, water or air and water, injected successively or simultaneously. The filter material bed rests either on a

  floor above a chamber for taking in filtered water and

  washing fluids, either on the bottom of the filter,

titrated by a layer of granular materials of high granulome-

sort or a layer of concrete.

It has long been established that the most effective washing of a granular material bed filter is washing

  with air and water injected into the filter mass, from bottom to top.

In the case where the filter material rests on a plane

expensive, this washing is usually done by means of nozzles

  fixed in perforations made in this floor; these bu-

  brines have a hollow rod provided at its lower part with one or more vertical slots and plunging into the chamber located below the floor and into which the air and washing water are injected, and a perforated head emerging above of

floor in the filter media. It is well known that this dis-

position is poorly suited in the case of filtration of a very clogging and / or corrosive fluid. Indeed, the perforated plate which constitutes this floor, is subjected at the end of the filtration cycle to a high differential pressure corresponding to the loss of

charge due to the flow of the fluid through the filtering mass

  te and, in the case of a filter operating under pressure and whose nozzles are found to be accidentally obstructed, at the operating pressure of said filter which may be several bars. This floor must then be reinforced with vertical bars - 2 -

  and we end up with a very heavy and very expensive structure.

On the other hand, when the fluid to be filtered has a characteristic

  corrosive, all parts of the filter in contact with it

must receive a coating which is inert to corrosion and which

Plication should be particularly careful. It is well known that the operations of applying this coating and preparing

  previous surfaces in the room limited by the bottom of the wire-

  tre and the underside of the floor are very delicate and expensive. Due to the difficulty of these operations, arrangements must be made to allow periodic inspection of the condition of the

coating of this room.

  To overcome the drawbacks of this arrangement, it is

generally proposed either the realization of a waterproof floor

  placing on a certain number of supports transmitting to the bottom of the device the forces generated by the operating pressure due to the flow through the granular material, ie the filling of the bottom of the filter with inert concrete which, in this case also , transmits the forces due to the charge pressure to it. In the

  two cases, we have a pre-

  mier collector with perforated ramifications ensuring collection

  of the filtered fluid and the distribution of the washing water and

  above a second collector also provided with perfo- ramifications

  and intended to distribute the washing air. In case the

  fluid to be filtered is corrosive, these distribution assemblies can

  can be made of plastic or metal protected by an anti-corrosion coating, this coating can in this case

  run without difficulty outside the filter.

  The latter solution, however, has four drawbacks.

main advantages: - It remains expensive since it requires the implementation of two distribution systems; - It does not allow, during washing, the distribution of an emulsion of water and air since the two fluids are injected separately. Washing efficiency is therefore not as good as that obtained with a floor with grooves; - Water and air distribution is generally not ensured

  only by the ramifications, which leads to a poor washing of the ma-

material placed above the collectors. When the collectors

  themselves are punctured, good repair is difficult

tition of fluids due to the difference in level between the col-

- 3 2485385

reader and its ramifications;

- It leads to having between the two distribution systems

tribution a layer of granular material with sufficient particle size

fisante not to be expanded under the effect of the washing water flow but not too important so that there is no

penetration of the filter layer into its pores.

  The subject of the present invention is a bed filter of granular materials which overcomes all the drawbacks of both.

  provisions described above and adopted so far.

  The filter according to the invention comprises means placed below the bed of granular materials for the recovery of the filtered water and for the simultaneous introduction of air and washing water.

  in order to ensure a backwash of the bed of gra-

nular, these means comprising a manifold provided with ramifications and resting on a sealed support surface, and is characterized in that this manifold is unique and comprises a duct for the inlet of washing air and a duct for the outlet of

the treated water and the arrival of the washing water, and in that the col-

  reader and its ramifications carry at their upper part of the nozzles, of known type, arranged so that the slots provided at their lower part are all at the same level inside

of the collector and its ramifications.

This arrangement ensures good distribution of the water to be treated during filtration, by allowing preferential passages and dead zones to be avoided in the filtering mass. It also makes it possible to obtain the distribution of a well distributed water and air emulsion during washing with a strictly identical air and water flow rate for each nozzle, whether it is fixed to

  the collector or its ramifications.

  The pipe for the washing air supply may

  plug at the top of the collector or be lateral. The pipe for the washing water supply can lead to the

lower part of the collector or at its upper part.

The waterproof support surface can be constituted by

  a floor or a concrete filling placed at the bottom of the filter.

  The nozzles carried by the ramifications are pre-

identical to those worn by the collector. Heads

nozzles are thus also on the same level.

In an advantageous embodiment of the invention, each nozzle is mounted in an orifice made in the upper part of the collector or one of its ramifications by means of an expandable ring fitted into a base perforated in its

center, the base and the ring having a lower height when

  that they are mounted on the collector only when they are

  tees on a branch of it. An embodiment of a filter according to the invention has been described below, by way of non-limiting example, with reference to the appended drawing in which: FIG. 1 represents a sectional view of the filter according to the invention ,

  Figure 2 is a cross-sectional view of the collection

tor, to the right of its connection with a pair of ramifications.

  As shown in Figure 1, the filter follows

  before the invention comprises a metallic enclosure 1, closed, containing

nant a bed of granular materials 2 resting on a floor 3 whose flatness is ensured by concentric support rings

  4 transferring the pressure force to the convex bottom of the filter.

  This enclosure is provided with a pipe 5 for the rear

  of the water to be treated and the outlet of the washing water, from a cana-

line 6 for the outlet of treated water and the arrival of water from

  washing, and of a pipe 7 for the arrival of the washing air.

  A manifold 8 which is here diametrical, rests on the plane-

expensive 3; it has a plurality of branches 9. The manifold and the branches are provided with nozzles 10 and

11 whose heads all emerge at the same level in my mother's bed

  granular materials 2. The pipes 6 and 7 open into the collector 8, respectively at its lower part and at its part

upper, while the pipe 5 opens at the upper part

enclosure 1.

  The nozzles 10 and 11 are identical. Each of them

comprises a head 12 which is provided with a series of slots 13 and includes

  provided with a tube 14. This has at its upper part

a hole 15 and a slot 16 in its lower part.

Each of the nozzles is surrounded by a base 17 or

  17 ', made of plastic, which is placed directly on the collec-

  on one of its ramifications, its underside

  perfectly fit while its upper face is flat.

This base is pierced in its center with a hole located in the corner

  cidence with the orifice provided in the upper wall of the manifold or the branch for the passage of the tube 14 of the nozzle. A -5 - expandable ring 18 or 18 'is placed in this hole and surrounds

  with clearance the tube 14 of the nozzle. This ring has a glue

rette 18a or 18'a which is blocked between the base and the head 12 of

the nozzle; its lower part is expanded and ensures the blocka-

mechanical aging of the assembly, as well as maintaining the seal. The base 17 and the ring 18 have a lower height

  respectively that the base 17 'and the ring 18' so that, mal-

depending on the level difference, of the order of 40 to 50 mm, which exists

between the upper wall of the manifold 8 and that of a branching

tion 9, the heads 12 of the nozzles are at the same level; given the identity of nozzles, their slots 16 are also at

same level.

  During filtering, the liquid to be filtered is introduced through the

line 6, is filtered through bed 2, enters the ramifications

  tions 9 and the manifold 8 by the nozzles 10 and 11, and is eva-

cué by the pipe 6.

  At the time of washing, the washing air and the washing water are introduced into the collector respectively through the pipe 7

and through line 6. An air mattress 19 is established, inside the

  header 8 and ramifications 9, above water

wash 20, the separation level being substantially mid-high

  slot 16. Air and water form an emulsion which crosses

is the tubes 14 of the nozzles and to which is added air entering these tubes through the holes 15, to enter the bed 2 through the slots 13. The slots 16 being at the same level, the ratio

air / water of the emulsion is the same for each nozzle.

The collector 8 and its ramifications 9, as well as the

  nozzles 10 and 11 are metallic or plastic.

  In one arrangement of the invention, the collector and its ramifications are of rectangular section; in this case, the base

located on the collector is possibly deleted.

  The filter according to the invention is particularly reliable for the filtration of sea water on off-shore platforms; it brings together the advantages of space and weight

  reduced to the efficiency of a simultaneous air and water wash.

It goes without saying that the present invention should not be

  considered to be limited to the embodiment described and represented

  tee, but on the contrary covers all variants.

- 6 -

Claims (7)

1. - Bed filter of granular materials comprising means placed below the bed of granular materials for the recovery of filtered water and for the simultaneous introduction of air and washing water to ensure washing at against the current of the bed of granular materials, these means comprising a collector   with branches and resting on a watertight support surface   che, characterized in that this collector (8) is unique and comprises   a pipe (7) for the supply of washing air and a pipe   connection (6) for the outlet of the treated water and the arrival of the washing water, and in that the collector (8) and its ramifications (9) carry at their upper part nozzles (10 and 11) , Of type known, arranged in such a way that the slots provided in their part are all at the same level inside the manifold and its ramifications.   2. - Filter according to claim 1, characterized in that the sealed support surface is constituted by a floor (3). 3. - Filter according to claim 1, characterized in that the sealed support surface is constituted by a filling of concrete placed at the bottom of the filter.   4. - Filter according to any one of the pre- claims   cédentes, characterized in that the nozzles 11 carried by the   ramifications are identical to that (10) carried by the collection tor. 5. - Filter according to any one of the pre- claims cédentes, characterized in that each nozzle (10 or 11) is   mounted in an opening in the upper part of the collar reader or one of its ramifications by means of an ex-   pansible (18 or 18 ') fitted into a base (17 or 17') perforated in its center, the base and the ring having a lower height when they are mounted on the manifold (8) than when they are mounted on a branch (9) thereof.   6. - Filter as claimed 5, characterized in that   that the expandable ring and the base are made of plastic.   7. - Use of the filter according to any one of the   previous claims for the filtration of seawater and corrosive liquids.