GB2197648A - Mobile towed unit for sludge treatment - Google Patents

Abstract

A mobile unit serving to clean up mud pits on site (monitored and controlled by a computer recording on site the parameters for the sludge to be filtered) is formed of a mobile platform (1), supporting the whole installation, which consists particularly of a control-and-operation cab (9) carried on the rear portion (3) of said platform (1) and comprising the means necessary for control and operation of the various components such as pumps, valves, motors, agitators, etc., along with sludge-treatment receptacles (19-23) and vats containing the treatment products which are moved by pumps in said receptacles; a lamellar separator (29) that receives the pre-treated sludge, subjecting it to an initial elimination of water before transferring it to a thickener (8) where it is stirred slowly before continuing to a filter press (30) that separates it into a cake, which is dropped into a receiving hopper, and clarified water that is, then, either joined with that from the lamellar separator (29) or else sent, under action of the pumps which are slave components of the control and monitoring unit, to any desired point in the installation, to modify the rheological properties of the sludge at that location; the whole complex being subdivided into a permanently-fixed unit on the trailer, including the cab and its components, the thickener and the filter press, plus a unit transportable separately and comprising the rest of the installation elements, especially the treatment tanks and the lamellar separator, each of the two units being provided with an inspection catwalk which can be reacted into a position for the unit to be moved. <IMAGE>

Description

MOBILE TOWED UNIT FOR SLUDGE TREATMENT This invention relates to a mobile towed unit for sludge treatment. Numerous industrial, mining or farm-based treatments entail the formation of large quantities of sludge in a mixture of water and various solids. Thus, for example, a drilling operation leads to gradually casting aside, in a corresponding sludge, waste drilling fluids that are not reusable and which consist of an aqueous mixture, including chemical substances with a high pH factor and suspended mineral particles in a wide variety of sizes and types. Likewise, various farm-based treatments; such as those for sugar beets or olive pressing, leave behind, in useless pits, large amounts of malodorous sludge formed by a mixture of water and pulp that needs separating.

Out of respect for the environment we need to be able, on the one hand, to treat the water for the sludge in it so it will not be a pollutant, then separate the water and return it harmlessly to the hydrographic network and to be able, on the other hand, to dehydrate the solid matter sufficiently and compact it to a minimal volume so it can, at the least-possible cost, be shovelled into containers and be trucked away or moved by rail to some place it can be used again, as is the case with farm-based solid residues (cattle feeds, "copies", etc.), or else disposed of at dumps or put in landfills, vacant fields or the like, without the risk of polluting or incurring any major expense, such as is true particularly with regard to drilling-mud residues or sewage treatment.

As concerns drilling-mud residues, at present we do not know how to dehydrate the solid matter sufficiently so it can be carried off by dump truck, for example. In fact, since it is still too much of a liquid after centrifuging, we are obliged to add considerable quantities of cement to solidify it before shovelling, which is very expensive.

Another aspect of these problems is that the ace tivity which gives rise to the formation of these sludges is not necessarily of a continuous nature, but is often sporadic, as is the case especially where farm-based treatments are concerned ; or even of a temporary nature as is true, for example, with test drilling as compared with production drilling, in which case the drilling equipment has to be moved from place to place ; or it has even a purely-seasonal character to it, as when it is a question of confronting the enormous increase in sewage, caused particularly in seaside resorts by the summer tourist season, and ensuring its immediate quick treatment.

For these reasons it is necessary that a sludge-treatment system be mobile in order to be able to install it right where it is needed during a period that occasions the formation of sludge. It is also necessary that the system not be too bulky, though having a high treatment capacity (20-to-90 cubic meters of sludge per hour), since locations set aside for oil-well drilling, for instance, are becoming scarcer all the time.

The invention brings a solution to the problem described above, and its subject is a mobile towed units for sludge treatment that offers, for overall dimensions reduced to the regulatory standards for being moved over highways, relatively-high treatment capacity with respect to its volume.

In accordance with the invention, the mobile towed unit for sludge treatment comprises, as regards both design and operation - a mobile platform that can be moved directly to the job site where it is secured in place, - means that are provided on said platform for fixed or separable mounting of sludge-treatment components, of a control cab rigidly mounted on said platform and including the means required for control and operating regulation of diverse equipment like treatment-product vats, motors, agitators, scavenging pumps, hydraulic agitators, scavenging pumps, hy#r.u.lio cylinders, valves, regulators, etc. to ensure progression of the sludge to be filtered to its various treatment sta- tions, and the afore-mentioned cab has a reinforcing framework that p#ermits, right on the unit's job site, installation and fixed mounting on the roof of said cab, put at the back of the platform, of a removable structure, for storing and initial filtering of the sludge, which includes sludge receiving-and-treating tanks, provided with agitators, intended to receive the sludge being treated and also the preliminary treatment products e.g. poly-electrolytes, lime and ferric chloride, contained in the control cab vats; and - a lamellar separator, associated with said sludge treatment tanks into which the sludge, pre-treated in said tanks, is discharged via ducts in order to dump there the sludge already deprived of most of its water, said lamellar separator being mounted above a thickener positioned on the low portion of the plat form beside the cab and from which the resultant flock is sent by a pump to a band-type filter press held on the high front portion of the platform, at as high a level as possible and on the outer edge of said platform.

Thus we provide a mobile treatment unit whose main portion, the semi-trailer supporting the control cab, the thickener and the band-type filter has an overall width not in excess of the 2,50 meters prescribed by vehicle regulations. However, in order to provide quick access from the cab to the various treatment-unit components, on the side of the unit at two levels there is a catwalk with a guardrail, and when being in transit the unit can be retracted in the plane of the cab's longitudinal face, and the cab has a ladder connecting the two superimposed catwalks.

According to a preferred form of embodiment, the mobile platform consists of a semi-trailer that can be hitched to a self-propelled tractor, the band-type fil ter press being located above the hitching point on the highest portion of the semi-trailer. Thus, between the ground and the point of discharge by the band-type filter of the cake of material from which the water has been removed, there is enough room, on the filtering units operating site, for inclusion of a receiving hopper which can, after filling, be mounted, in a usual manner, a a truck supplied with hydraulic equipment for lifting it At the same time, on the treatment site perfect seating of the treatment unit is obtained because the semi-trailer is advantageously equipped, in known manner, with supporting hydraulic jacks, each of which has stabilizing plates.

Preferably, the evacuation duct for the water separated from the solid products in the band-type filter press is controlled by a pump that discharges said water into the piping that actually evacuates the clarified water removed from the solid products in the lamellar separator positioned high above the thickener unit.

Other characteristics and advantages of the invention wil become apparent from the following description in connection with the accompanying drawings which represent dIagrammatically by way of example, a preferred embodiment of the sludge-treatment unit.

In the drawings: Fig. 1 is a longitudinal elevation view showing the semi-trailer, the cab, the various upper vats and their agitators, the lamellar separator and the thickener, as well as at the front, above the point where the semitrailer is hitched to the tractor, the band-type filter; Fig. 2 is a diagrammatic view in side elevation to illustrate the path of the products in the sludge-treatment unit; and Fig. 3 is a plane top view of the cab mounted on the trailer, showing the various elements it comprises and the upper grating that gives access, from the side catwalk, above the lamellar separator which overhangs the thickener As can be seen altogether diagrammatically in i s 1 of the drawings, so that it can be moved over highway.

and have mobility overland, the mobile unit has essentia3.'y a semi-trailer, designated in its entirety by the reference 1, including a portion 2 which is, in the unit's mobile position, put on the tractor hitch above the machine r S drive wheels, plus an underslung portion 3 that, in usual manner, includes two axles 4 and 5 carrying wheels 6 and 7.

On the rear, underslung portion 3 of the platform there is a lower structure constituted by a thickener unit 8 and a control cab identified in its entirety by the reference 9 and comprising (see Fig. 3), on either side of a partition 10, two compartments 11 and 12 each provided with external access doors 13, 14 in which are windows 15, 16, respectively. In that cab the various manoeuvreing and control members of the sludge-treatment unit are securely mounted, and they will be described later.

Above the roof 17 of the cab 9 there is a reinforcing framework that includes posts, as at 18, that serve to support and hold sludge-receiving containers 19, 20, 21, 22 and 23 which communicate among themselves and each of which is provided with an agitator 24, 25, 26, 27 and 28, respectively. Above the thickener 8 there is a lamellar separator 29 whose function will be indicated later on.

A band-type filter 30 is secured on the raised, forward portion 2 of the semi-trailer, and the position of this filter, since it is a fairly heavy apparatus, anyhow, ensures good traction for the wheels whenever the trailer 1 is moved, inasmuch as it balances the load.

In the unit's working position after the tractor itself is unhitched, the semi-trailer is supported in usual manner by its forward portion, with the help of stabilizing plates that sit on the ground and which are shifted and kept steady by jacks 32.

The mobile treatment unit's superimposed struc tures are accessible via retractable or swingIng catwalks 33 and 34, on the one hand, for the substructure and 35, on the other, for the superstructure. Each of those catwalks, interconnected by a ladder 36, has a guardrail designated by references 37 and 38 for the lower one and by 39 for the upper one. As can be seen in Fig. 1 of the drawings, the forward portion 33 and rear portion 34 of the lower catwalk are connected by a stairway 37' that compensates for the difference in level.

A stiffening stanchion 141 advantageously connects the cantilevered forward portion of the lamellar dryer 29 and the upper portion of the band-type filter press.

As concerns the maneuvering-and-control cab 9 proper, divided into two compartments 11 and 12 by the wall 10, it contains all the necessary elements for treating the sludge. Accordingly, the forward compartment 11 of that cab has a cabinet 142 for storing effects, prints, documents and the like, as well as two panels 43 and 1414 for the various electrical feed and control circuits, control boxes 145, 46, 147, 148 and 49 for the motor adjusters (not represented) of the various pumps diagrammatically illustrated in Fig. 2.

A table 50, which covers over the drive motor 52 of the main pump 51, completes the installation.

In the second, rear compartment 12, essentially laid out axially, is the main pump 51 which can advantageously be of the "MOIN > AU"-type with an eccentric impeller that draws the sludge from the mud pit to be cleaned up and sends it to the upper containers 19 to 23 mounted in place, above the maneuvering-andcontrol cab 9, by way of the reinforcing-and-support post 18.

A motor 52 for the pump 51 is installed in compartment Alongside the main pump 51 in compartment 12 there are two treatment-product vats 53 and 54 and, at its end, an expansion tank 55 filled with sludge and inc tended to protect the main pump 51 from operating without a load. Cross-wise alongside that expansion tank 55 there are two vats 56 and 57 which, advantageously, have the same capacity as vats 53 and 54 ; that is, 14 cubic meters each, for example.Between vats 53 and 54, on the one hand, and vats 56 and 57, on the other, two pumps 58 and 59, respectively, are advantageously arranged, which pumps allow the treating liquids from the vats to be compressed into the upper communicating receptacles 19, 20, 21, 22 and 23 that constitute, as a whole, the treatment chamber proper for the sludge which, depending on its nature, is treated by flocculation or coagulation, or else via both processes simulta neously.

Above the pumps 58 and 59, as well as the main pump 51, there is a grating 60 that gives service per sonnel access, via a small stairway 61, to the forwards located vats 56 and 57 which contain treatment products. ts is evident in Fig. 3, each of the vats 53, 514, 55, 56 and 57 located in cab 9 is equipped with an agitator 62, 63, 64 and 65, respectively, intended to en- sure constant stirring of the treatment products.

Moreover, as is shown in Fig. 2, a pump 66 is provided below the thickener 8 for transmitting the flock from the latter, by way of duct 67, to the bandtype filter press 30. At the lower portion of this filter press 30 a drain duct 68, controlled by a pump 69, evacuates the clarified water through a passage 70 that is in direct connection with a duct 71 via which the water removed from the sludge leaves the lamellar separator 29. Via a passageway that is not represented and which is controlled by a volumetric valve also not shown, itself controlled from the cab 9, from duct 71 one can, if so desired, reinject water at any desired point of the installation, especially into the thickener, in case fluidity of the flock should prove insufficient to allow it to be treated in the b2nd-type filter press 30.

A computer, connected to sludge-analyzing device-.

that supply it with the desired parameters (density, fluidity, grain size of the solid, plasticity, etc.) ensures adjustment of the valves and pumps controlling the path followed by the sludge in the installation, as well as the exact proportioning of treating products for ad ding to said sludge before separation of the water and the solid matter it holds in suspension. Hence it is possible to adapt the treating unit to any quality of sludge encountered.

The functioning of the mobile treatment unit is easi- ly followed in Fig. 2. The sludge, drawn from the mud pit by the pump through expansion tank 55, is loaded into the upper preliminary-treatment vats 19-23 that constitute an overall capacity 72 that is constantly stirred by the agitators 24-28. As a function of the analyses and steps taken, by way of pumps 58 and 59 in this capacity there is- added, as desired, the required quantity of treating product. The sludge is then sent, through ducts 73 and 74, to the lamellar separator 29 where it is subjected to an initial separation of the water contained in it, said water being evacuated through duct 71 which communicates with duct 70 coming from the filter press 30. From the lamellar separator the already-thickened sludge passes into the thickener 8 located below where it is gently stirred by a vane-type agitator not specifically represented.

The flock formed in the thickener is then sent, through pump 66 and duct 67, to the band-type filter press 30 which concludes its treatment and ejects it, via an inclined chute 75, into an appropriate receiving hopper, the cake formed of practically anhydrous solid matter and evacuates, through drain duct 68 and pump 69, the separated water which it sends, via duct 70, to join that evacuated by duct 71.

Incidentally, an air conditioner 75 can be mounted in the cab 9 enclosure 12 for regulating the temperature inside the cab.

The sludge mobile treating unit has been described and represented here only by way of example, and various modifications of details could be made in the form of embodiment indicated, within the scope of the invention Thus, in particular, pump 66 could be made a slave component of the drain pump 69 of the filter press 30.

The lamellar separator referred to can be a gravity separator such as made by Passavant, comprising a plurality of lamella plates inclined at 550 to the horizontal in a casing having inlet and outlet; suspended solids separate out as sediment therein and can be discharged over a sludge collector wherein they are thickened e.g. by adding ferric hydroxide.

The band-type filter press, e.g. made by Passavant, has, driven in a sinuous path over a plurality of rollers, an endless filtration band on which the solids are retained and eventually scraped off.

Claims (11)

CLAIMS:

1. A towable, mobile sludge-treating unit which includes, (a) a mobile platform that can be moved directly to the job site where it is fixed in place, (b) means provided on said platform for secure, permanent mounting of sludge-treating components, a control cab fixed to said platform and comprising the necessary means for controlling and monitoring the operation of the equipment present in the unit to ensure progression of the sludge to be filtered to its various treatment stations; said cab having a reinforcement framework that will permit, at the unit's operating site, installation and securing, on the roof of said cab mounted on the back of the platform, of a separable storing and preliminary sludge-filtering structure which comprises sludge receiving-and-treating tanks each provided with an agitator, intended to receive the sludge to be treated, along with pre-treatment products, contained in the vats of the control cab; and (c) a lamellar separator, associated with said tanks for preliminary treatment of the sludge, into which is discharged, by way of ducts, the sludge first treated in the aforementioned tanks, the lamellar separator being mounted, in order to dump there the sludge from which most of its water has been removed, above a thickener device positioned on the lower portion of the platform beside the cab and from which flock produced is transmitted by a pump and a duct to a band-type filter press on the front portion of the platform at as highest level possible on the outer edge of the platform.

2. A sludge-treating unit in accordance with Claim 1, which has on its side at two levels, one of which corresponds to the floor of the cab and the band-type filter press and the other to the base of the sludge receiving-and-treatment tanks and the lamellar separator, a catwalk provided with a guardrail, and when moved over highways the whole unit can be retracted in the plane of loncitudinal face of the cab which has, on its wall, a larder connecting the two superimposed catwalks.

3. A sludge-treating unit in accordance with Clain 1 or 2, wherein the mobile platform consists of d semi-trailer that can be hitched to a self-propelled tractor, the band-type filter press being put above the hitch point on the highest portion of the semi-trailer.

4. A sludge-treating unit in accordance with Claims 1, 2 or 3, wherein the duct for evacuating the water removed from the solid matter in the band-type filter press is controlled by a pump that discharges said water into the piping which evacuates the clarified water separated from the solid matter in suspension in the lamellar separator located high above the thickener.

5. A sludge-treating unit in accordance with any of Claims 1 to 5, wherein an expansion tank, arranged cross-wise in the control-and-operating cab, is interposed in the sludge circuit ahead of a main feed pump.

6. A sludge-treating unit in accordance with Claim 5, wherein a transverse grating, provided in the substructure of the treatment unit, affords access via a stairway to the product-treatment vats which are located at the end of the cab parallel to the expansion tank protecting the main sludge pump.

7. A sludge-treating unit in accordance with any preceding claim, which is constructed so that water leaving said band-type filter press can be recycled at any point in the installation to allow modification of the rheological properties of the sludge to be treated.

8. A sludge-treating unit in accordance with any preceding claim, wherein said filter press is located on the highest portion of the trailer.

9. A sludge-treating unit in accordance with Claim 8, wherein said filter press is at the front end of the raised, forward portion below which the trailer is hitched

10. A sludge-treating unit in accordance with Claim 1 substantially as hereinbefore described with reference to the accompanying drawings.

11. A method of treating sludge in a unit as claimed in any preceding claim, substantially as hereinbefore described.