FR2628336A1 - Self-regenerating emulsion separator - with packed bed retained by membrane inflated by fluid - Google Patents

Abstract

A self regenerating coalescer sepg. emulsions containing sediments in suspension has a cylindrical vessel with a compartment packed with granular material, a deformable membrane forming the lower or lateral wall of the compartment, hydraulic or pneumatic fluid deforming the membrane, a series of settling compartments above the packed compartment, an inlet for emulsion, outlets for sepd. liqs., and an outlet for liq. used to regenerate the granular material. A method of sepg. the emulsions is also claimed. USE - For oil-and-water emulsions.

Description

The present invention relates to a device for the separation of two immiscible liquids emulsified in the presence of sediment, on a material promoting coalescence.

The devices approaching the present invention and known to date can be classified into two categories: coalescers and coalescing filters.

Coalescers are devices provided with linings or porous materials which promote the gathering of fine emulsified droplets into larger ones which settle naturally by gravity and can therefore be separated. They are self-healing with respect to the two liquid phases; but they have the drawback of being sensitive to non-deformable solid particles which quickly clog the linings or porous materials. Their application is therefore limited to the treatment of liquids free of solid pollutants, such as for example condensates polluted only by oils.

Coalescing filters are equipment that works like sand filters, but whose sand has been replaced by an oleophilic filling, which also retains the emulsified oily liquid and sediments. When the lining is saturated (with liquid and -sediments), it is regenerated against the current, but at the cost of a sharp reduction in the average flow rate of the installation and by creating a large volume of washing water.

Improvements have been made to these materials with a view to reducing the incidence of clogging, for example by use, as described in European patents EP 0 004 724 or
EP 0 207 797, of coalescing materials constituted by fiber beds, the ends of which are caught between movable plates; it is the relative movements of these plates which make it possible to put the coalescing beds in a compressed or relaxed state. However, in addition to the fact that very special coalescing materials must be used, the handling of these materials is very uncomfortable, and their fragility is certain.

In French patent FR 77 29775, the coalescing material is a granular material which is housed between rigid plates, provided with mechanical spacing members. This system also has a major lack of maneuverability.

The present invention overcomes these drawbacks inherent in previous embodiments. It relates to a self-regenerating device for the separation by coalescence of emulsified liquids which also contain suspended sediment, which consists of a cylindrical tank comprising a) a filling compartment lined with a granular material promoting coalescence where s '' coalesces the emulsion, b) a set of compartments where the decantation of demulsified fluids takes place, and c) means for supplying the emulsified liquids, means for separating and extracting the separated liquids, and means for evacuating liquids used for the regeneration of the granular material promoting coalescence, the characteristic of which is the filling compartment, lined with granular material promoting coalescence, the lower wall of which, or where appropriate the lateral cylindrical wall, is a deformable membrane actuable by means of a hydraulic or pneumatic fluid. Thanks to this device, the coalescence of the emulsified liquids is obtained by passage through the compacted bed of granular material promoting coalescence; then when the bed of granular material is clogged, it is unclogged by rinsing against the current by removing, within the coalescer apparatus according to the invention, the regeneration water from the purified water, the bed of material granular then being in the unpacked state., the compacting and unpacking of the granular material being carried out by a hydraulic or pneumatic action exerted on the deformable membrane constituting one of the walls of the compartment where the granular material is housed.

The regeneration phase is remarkably easy owing to the fact that the bed of coalescing granulated material is completely loosened, that it can then be mechanically stirred, and that it is thus very easily rid of clogging sediments. The coalescers according to the invention are appreciated for the autonomy of their operation in regeneration and for their small size.

Various other characteristics emerge from the detailed descriptions, given below with the accompanying drawings, of an embodiment and its operating cycle.

THE COALESCEUR
The coalescer represented diagrammatically in FIGS. 1 and 2 is more particularly intended for the treatment of emulsified oils in waters otherwise loaded with solid sediments and, where appropriate, with viscous and sticky oils. It consists of a cylindrical tank (1) with a vertical axis, the lower part of which is formed by a curved bottom (2) to which a conduit (3) is connected, itself connected to a source of pressurized fluid. At the upper part, there is a curved roof (4), crossed in its center by a rotary axis (5) connected to a motor assembly actuating it in continuous or alternating rotation. The curved roof (4) is also provided with a vent (6).

At least three pipes pass through the cylindrical part of the body of the device or ferrule - a pipe fitted with a three-way valve (34), connected at
(7) to the supply line of the fluids to be treated and in (8)
to the rinsing water outlet pipes and a
pressure switch (9), and which is extended by a strainer (10); - the outlet of purified water (11), connected to the internal chamber
(12) - the outlet for the separated oils (3) connected to the
oil recovery (14).

It is organized into a coalescing zone, a separation zone for demulsified fluids in the coalescence zone, and a recovery and evacuation zone for purified water and demulsified oils.

For this purpose, it is internally divided into seven main capacities which are described below.

In the lower part, there is a first capacity (15), limited by the curved bottom (2) and by an elastic membrane (16). This capacity is connected by the piping (3) to a source of pressurized fluid, by means of which it is emptied or filled as required.

A second compartment (17), of variable volume, is limited at its lower part by a deformable membrane (16) and at its upper part by a perforated sheet (18). It is filled with a granular material promoting coalescence. This compartment also contains a mixer (19) connected to the shaft (5) and a strainer (10).

This second compartment constitutes the active zone of coalescence. By the play of the deformable membrane (16), its volume can increase at the expense of that of the first capacity (15).

A third capacity (20) between the perforated sheets (18) and (21) contains a lining with a large contact surface.

The fourth capacity (22) is a chimney limited by the perforated sheet (21), by the cone (23) and by the cylinder (24), which has openings (25) leading to the fifth capacity. The openings (25} are so arranged that they allow a uniform distribution of the liquid in the following capacity. It is advantageous to give a form of vertical slots to these openings and to have them symmetrically on the chimney (24). ends in its upper part with the weir (26).

 The fifth capacity (27) is a chamber limited by the cylindrical envelope (1), by the cone (28) in its lower part and by the cylinder (29). It is partially occupied by a separator with parallel plates (30). In the upper part, a threshold (32) is arranged by which the liquid occupying the capacity (27) overflows towards the capacity (14).

These third, fourth and fifth capacities constitute the zone where the effective separation of the demulsified fluids takes place in the second compartment (17).

The sixth capacity is the water lift chimney, consisting of the space between cones (23) and (28), tubes (31), the cone (33) and the chamber (12). It is provided with a pressure balancing tube (34) and is connected to the outside by the piping (11). The tubes (31) are arranged symmetrically with respect to the axis of the device, so as to avoid the establishment of preferential currents; the number of tubes and their cross-section depend on the flow rate of the device and the admissible pressure drop. Preferred are constructions with at least three tubes. The device shown in Figure 2 has four.

The seventh and last capacity is the oil recovery chamber (14), which opens outwards through the piping (13).

This set of sixth and seventh capacities constitutes the recovery and evacuation zone for demulsed and separated fluids in the preceding compartments or capacities.

The elastic membrane (16) which constitutes the flexible wall between the first capacity (15) and the second capacity (17) is in the form of a spherical cap which approximates the shape of the curved bottom (2) when no pressure is not sent through the conduit (3). It is fixed to the body of the device by its outer edge. It is preferably made of synthetic elastomer (for example, nitrile rubber or fluorocarbon elastomer).

 The granular material promoting coalescence which fills the capacity (17) is composed of grains endowed with sufficient mechanical strength to withstand the forces imposed by the mixer (19). Its particle size is appropriate to the composition of the medium to be treated and to the nature and size of its solid pollutants. A particle size of 0.4 to 0.8 mm is generally preferred. It can be a sand or grains of glass, if necessary treated to be wettable by the emulsified liquid.

In the frequent case of oil emulsions, it is preferred to use for this purpose an oleophilic resin, as described in the French patent N0 70 07641.

The lining which fills the capacity (20) consists of a mattress of material with a large surface, preferably wettable, like the preceding lining, with the emulsified liquid. It can be made of braided stainless steel straw, teflon shavings, etc. We readily use oleophilic resin granules, of the same particle size as that which constitutes the lining of the capacity (17), or more big.

The coalescers of the invention operate according to an alternation of treatment and regeneration cycles, as described below.

THE PROCESSING CYCLE (see Figure 3)
The device is supplied either by pump or by gravity through the conduit (7), taking care not to exceed a maximum flow rate which is a function of the geometry of the device and the qualities of the granular coalescing material, and which is defined like the one beyond which the coalesced drops are re-emulsified and are therefore irrecoverable. With oleophilic resins as described in French patent N0 70 07641, it is of the order of 10 to 30 cubic meters per square meter of coalescing bed and per hour
The lining of the capacity (17) is compacted by sending a pressurized fluid through the conduit (3) into the capacity (15).

The mixture to be treated is introduced by the strainer (10) into the lining of the tank (17); the fine oil droplets coalesce on the lining, and the oil comes out through the perforated sheet (18) in the form of larger droplets which collect in the lining of the capacity ~ (20), and come out of it through the perforated sheet (21) in the form of large drops. Only the sediments, and possibly very viscous and sticky oils, remain trapped in the strainer (10) and in the lining of the tank (17): the filtering lining is therefore self-healing with regard to the aqueous and oily liquid phases.

The water charged with drops of oil, but no longer containing sediment rises through the chimney (22); the largest drops go up directly by simple density difference effect at the top of the device and separate in the chamber (14) passing through the weir threshold (26); the finer drops penetrate with the water which transports them into the chamber (27) via the openings (25), then pass through the parallel plates (30) which promote their mechanical separation by shock effect and wall effect. The principle of operation of these parallel plates is well known to those skilled in the art (lamellar decantation) and widely used in the production of both separators and centrifuges. The coalesced oil flows along the plates and collects at the upper part, while the water is coming back down, takes the path of the sixth capacity where it rises and from where it overflows by the threshold constituted by the cone (33) in the evacuation chamber (12).

The very principle of recovering water and oil by overflow on two thresholds at different levels in two branches of a tube in 'lU'l is well known to those skilled in the art, e # t it n' is not necessary to detail it here. It is simply recalled that the water pouring onto the upper level of the cone fixes a hydraulic reference level. The thresholds (26) and (32) being higher than the threshold (33), there will be oil overflow by these thresholds only when the height of oil in the fourth and fifth capacity has reached a sufficient value, given by the formula H = h / (ld), where H is the oil height, h the difference in level of the thresholds and d the density of the oil.

 The water which overflowed through the cone (33) is evacuated by gravity through the chamber (12) and the piping (11). The oil overflows through the thresholds (26) and (32) and flows into the chamber (14), then always by gravity to the outside through the piping (13). The separation of the emulsions is therefore automatic and self-regenerating.

As for the sediments remaining blocked in the strainer (10) and in the lining occupying the capacity (17). It follows a gradual increase in the pressure drop which can be followed on the pressure gauge (9); regeneration should be carried out when clogging is considered excessive.

THE REGENERATION CYCLE (see figure 4)
The device being no longer supplied, the capacity (15) is emptied, which has the effect of loosening the lining of the capacity (17).

The shaft (5) is put into continuous or alternating rotation: the mixer (19) completely loosens the packing and the friction of the grains on each other detaches the viscous and sticky oils trapped and the sediments.

The three-way valve (34) being inverted, the treated water which resides in the fourth and fifth capacities flows towards the bottom of the device, and in the process rinses against the current the packings and the strainer (10) , then is discharged with the sediments entrained by the piping (8).

When the water level reaches the bottom of the openings (25), the regeneration phase is automatically terminated. If it is feared that supernatant oils will escape with the rinsing water, the operation is stopped by closing the valve (34) when the water level (that of the water-oil interface) reaches the top openings (25). We can then return to the treatment cycle.

The invention is not limited to the embodiment shown here and described. Various modifications can be made without altering its scope. For example, a variant of the device will consist of delimiting the second compartment at its upper part by the perforated sheet (18) and at its lower part by a rigid bottom, while the side wall will be formed by the elastic membrane in shape of cylindrical sleeve fixed by its lower and upper edges to the cylindrical body of the device. The pressure fluid which controls the compaction of the granular coalescence filling is then distributed in the space between this membrane and the body of the device that '' it fills by compressing the granular material; by releasing the pressure of this fluid, the membrane again comes to marry the cylindrical wall of the device and the granular material which it contains passes to the loosened state.

It is also possible to constitute a unit for separation by juxtaposition of several coalescence and decantation capacities operating in series or in parallel.

It is also possible to improve the operation of the installations which must work on liquids heavily loaded with emulsion and sediments, by placing a roughing filter or separator upstream of the coalescer according to the invention.

 The use which is made of this type of device is not limited to the use illustrated. The coalescer according to the invention is a general liquid-liquid separation system. It can, among other things, be applied without major modification to the separation of liquid-liquid systems consisting of a heavy continuous phase and a light emulsified phase, for example a chlorinated hydrocarbon containing emulsified water.

The devices according to the invention find their use, in particular for the treatment of industrial water, reservoir water, runoff water, ballast water, cutting liquids, washing liquids in the steel industry, for the extraction of gasoline and solvents, etc ...

Claims (10)

1. Self-regenerating device for the separation by coalescence of  emulsified liquids which also contain sediment  suspended, consisting of a cylindrical tank comprising a  filling compartment lined with granular material  promoting coalescence where the coalescence of  the emulsion, topped with a set of compartments where  decanting of the demulsified fluids takes place, and  provided with means for supplying emulsified liquids, means  separation and extraction of separated liquids, and  means of evacuation of liquids used for the  regeneration of the granular material favoring the  coalescence, characterized in that the compartment  filling filled with granular material favoring the  coalescence is a capacity whose bottom wall or  side wall is a deformable membrane, and in that  this membrane can be actuated by means of a fluid  hydraulic or pneumatic. 2. Apparatus according to claim 1, characterized in that the  deformable membrane forms the bottom of the compartment  filling filled with granular material favoring the  coalescence, and in that this membrane is actuated by  pressure variations of a pneumatic fluid or  hydraulic in a capacity located below this  membrane. 3. Apparatus according to claim 1, characterized in that the  deformable membrane constitutes the side wall of the  filling compartment lined with granular material  promoting coalescence, and that this membrane is  actuated by variations in fluid pressure  pneumatic or hydraulic distributed between the body  cylindrical of the tank of the device and this membrane. 4. Apparatus according to claims 1 to 3, characterized in that  as filling compartment lined with granular material  promoting coalescence is equipped with a mixer connected to a  vertical rotating shaft. 5. Apparatus according to claims 1 to 3, characterized in that  that the area where the decantation and separation of the  demulsified fluids includes a) a compartment containing a large area packing b) a chimney which surmounts it and which opens from above into  a recovery chamber, which communicates by  openings located in its intermediate part with the  next capacity c) a room partially occupied by a plate separator  parallel. 6. Apparatus according to claims l å 3, characterized in  that the means for supplying the emulsified liquids to be separated and  the means of evacuation of the liquids used for the  regeneration of granular material promoting coalescence  consist of piping fitted with a three-way valve  tracks, connected on the one hand to the supply pipeline of  emulsified fluids to be treated and piped  on the other hand to a strainer plunging into the  granular material promoting coalescence. 7. Apparatus according to claims 1 to 3, characterized in that  that the deformable membrane is made of elastomer  synthetic 8. Apparatus according to claims 1 to 3, characterized in that  that the granular material promoting coalescence is  consisting of oleophilic resin granules. 9. Apparatus according to claims 1 to 6, characterized in that  that the granular material regeneration liquid  promoting coalescence is taken from liquids  treaties residing in the compartments where the  decanting and separation of demulsified liquids. 10. Process for the coalescence separation of liquids  emulsified which also contain sediments in  suspension, consisting in treating liquids with  demulsify in a coalescing device by making them  pass through a compacted bed of granular material  promoting coalescence, collecting separated liquids  in capacities capable of operating their decantation, their  collection and disposal, then when the material bed  granular is clogged, unclog it by rinsing against  current by taking, from within the coalescing device,  regeneration water on purified water, the material bed  granular then being in an unpacked state; compaction and  decompaction of the granular material being obtained by means of a  hydraulic or pneumatic action on a deformable membrane  constituting one of the walls of the compartment where the  granular material.