MXPA06001918A - Lamellar decanting module and block comprising plates that can be vertical - Google Patents

Abstract

The invention relates to a lamellar decanting module comprising two interconnected plates, at least one of said plates being corrugated in such a way that the dips and peaks are inclined in relation to a first edge of said plate according to a non-zero degree angle and define inclined decanting tubes with the other plate. Said module is characterised in that the two plates (2, 3) have the same corrugated profile and are interconnected in connection regions defining a plane of symmetry (P) for the tubes (4) defined by said plates. A plurality of modules can be assembled in such a way as to form a block in which the plates are parallel to one of the faces.

Description

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MODULE AND LAMINAR DECANTATION BLOCK WITH PLATES THAT CAN BE VERTICAL I. TECHNICAL FIELD The invention relates to a system of sheets intended to separate by decantation, the solid particles in suspension in a liquid such as water, remarkably well adapted for the treatment of clarification of used waters, purification of surface waters or the production of industrial process water. II. TERMINOLOGY Next, different notions will be used with the following meanings: • Decantation plate or sheet = flat or corrugated surface installed in a tank called laminar decanter in order to ensure the recovery of the separated particles of the main fluid, • Decanting tube = duct of essentially polygonal shape, generally formed by the juxtaposition of 2 plates of which at least one is undulated, and placed at a certain angle with respect to the horizontal plane to ensure the liquid-solid separation, • Module = grouping of 2 plates placed in way to constitute the decanting tubes, • Block = grouping of several assembled modules in order to facilitate the operations of use, • Transition zone = first part of the decantation tube in which the transition is made between the turbulent and laminar spill, • Useful length = part of the tube Decanting located downstream of the transition zone, in which the separation of the phase takes place thanks to a laminar spill regime. lll. STATE OF THE PREVIOUS TECHNIQUE The current laminar decanters use one or the other of the following spill principles: in countercurrent: the decanted particles follow a downward movement, while the liquid in the process of treatment follows an upward movement, in cross currents: the liquid it follows a horizontal movement while the particles follow a downward movement in co-current: the liquid and the separated particles follow the same direction of current, generally descendant. The invention is particularly directed to the first category, ie that of the countercurrent decanting, which It is the most widespread in the industrial field. Most current systems (often referred to as "honeycomb") are based on the use of separation tubes, most often polygonal, oriented at an angle between 45 ° and 65 ° with respect to the horizontal plane. In practice, the plates used comprise an embossing, usually of trapezoidal shape, placed parallel to the vertical edge of these plates, and the inclination of the tubes thus formed is determined by that with which the plates are mounted with respect to the horizontal plane, that is, according to an angle between 45 ° and 65. Inside the tubes, hexagonal in shape when the embossing is trapezoidal, the settled decanted sludge spills on the inclined plane formed by the inner side of the hexagon (of which a small side of the trapezoidal shape), with a speed braked by the friction resulting from the importance of the contact surface between the sludge and sheets due to this trapezoidal section. Furthermore, the plates thus placed present a risk of flaming and plastic deformation when the weight of the deposit is excessive, which in practice requires the presence of specific hardening or of an over-weighing of the plates. The laminar decanters are thus, in the current state of the art, in practice constituted by a stacking of parallel plates (in the direction of the length of the decanter) but displaced with respect to each other to take into account their inclination, and the formation of a long assembly requires the maintenance, relative positioning and stacking of a large number of inclined plates. The assembly of the plates in modules and modules in blocks facilitates the use of these plates, by the realization on the outside of the decanter of a part of the assembly operations; However, the operations to be carried out in the decanter remain, which significantly increases the cost and demands a duration that is difficult to compress. In addition, the blocks, which are in the form of non-rectangle parallelograms, with the inclined lateral sides constituted by front and rear plates, are difficult to manipulate and are poorly adapted to equip the openings with a non-rectangular shape. Another type of laminar block commercially available and in a parallelapiped form, being constituted from vertical plates carrying inclined embossments with respect to the sides of these plates; such blocks are commonly used as an ordered packing to increase the contact surface in the gas-liquid or liquid-liquid contactors. But in this type of use, the successive plates are placed in a way to cross the embossing, in order to increase the effect of mixing by crossing currents, so that there are no legitimate tubes. A variant is described in the document US-A- ,384, 178, which describes a settling assembly formed of modules of two vertical plates forming together inclined tubes. More precisely, each module is formed of the assembly of two plates of different geometries, of which the first one is wavy and the other is substantially flat, so that the tubes have trapezoidal, almost triangular sections. More precisely, the second plate has concave grooves covering the ridges of the other plate, which allows a good relative positioning, but implies that the second plate penetrates the concave portions of corrugations of the first plate. These modules can be stacked, thus forming a network of substantially triangular tubes. But, because the plates have corrugations of the same direction but of different amplitudes, the tubes obtained by the stacking of two modules are smaller than those used in the center of each of these modules. The corrugations are not rectilinear, in this sense that the tubes are, at their ends, bent to be vertical, and that, in addition, the walls of the tubes have corrugations along their longitudinal axis. It turns out that this system includes plates of at least two different geometries, each one of them being complex, and that the tubes obtained have different and variable sections. They are inconvenient not only for the manufacture (time and cost related to the obligation to provide two types of manufacture), but also for the conservation (notably for the cleaning of the tubes, corrugated, elbowed and not identical).

Furthermore, it can be observed that this configuration of generally triangular tubes is more compact, and therefore heavier than that of the known blocks of hexagonal tubes. A common drawback of the various existing systems is that they need in practice the emptying of the openings, both for the operations of installation of blocks and for their removal. IV. TECHNICAL PROBLEM AND SOLUTION OF THE INVENTION The invention aims to mitigate the aforementioned drawbacks, by proposing a module (of two plates) and a laminar decantation system (in at least one block of plates) that combine at least certain following advantages: decantation in the tubes before entering the distant plates, to improve the efficiency and decantation, - use of a tube shape minimizing the surface of the sheets in contact with the spillage of decanted sludge, in order to reduce the friction of sludge-sheets, increase the speed of the sludge spill, minimize the section necessary to pass the spill of sludge, and thus increase the section available for the water pass, vertical arrangement of modules of which the undulations are inclined in order to improve their mechanical content and / or allow the decrease of thickness of the plates, minimization of the number of different compounds to be foreseen; minimization of the number of plates to assemble for the constitution of a module of given width but of great length, reduction of employment costs. The invention proposes for this purpose, a laminar decanting module, comprising two plates fixed to each other, at least one of these plates comprising corrugations of which the ridges and valleys are inclined with respect to a first edge of this plate at an angle not null and that delimits with the other inclined decantation tubes plates, characterized in that the two plates have the same undulated profile and are fixed to each other in the bonding areas defining a plane of symmetry for the tubes defined by these plates. The identity of the corrugated profiles of two plates allows those obtained by the same manufacturing process; and its symmetrical assembly allows obtaining tubes in a particularly simple manner. The crests and valleys preferably have a trapezoidal shape, so that the decantation tubes have a hexagonal shape, which corresponds to a structure that is both not very compact and robust. To facilitate the placement of the plates at the moment of assembly of the module, those are advantageously prepared to be symmetrical with each other in their assembly (identical), so that an overlap of the edges of these plates, has approximately a rotation, which guarantees the good positioning of the valleys (or of the ridges). These plates preferably have a rectangular shape for the obvious reasons of simplicity of manufacture and handling. Similarly, for similar reasons of simplicity, the tubes are preferably rectilinear, with no elbow at their ends. The inclination of the tubes with respect to said first edge is advantageously comprised in the range of 45 ° -65 °, preferably 55 ° -60 °, which seems to lead to very good decanting performances, when the plates are placed vertically in waters to be treated, with the first edge placed horizontally. The invention further proposes a laminar settling system comprising at least one block formed of several plates, of which at least one appears to constitute a module of the type defined above, which provides good stiffness. Such a block may comprise an odd number of plates, but advantageously comprises a plurality of modules, of which at least two modules are assembled in such a way that the modules jointly delimit other tubes, these modules Fixing each other in the areas that define a plane of symmetry for these other tubes. These other tubes advantageously have the same section as the module tubes, in which case the block constitutes a network of identical tubes, which then have substantially homogeneous performances at every point of the block. For obvious reasons of simplicity of manufacture, the modules are advantageously identical, which notably allows the block to have a rectangular parallelapped shape, the plates being perpendicular to one of the sides of this block. The plates extend preferably perpendicularly to the smallest dimension of the block, ie in other words that the plates extend according to the two largest dimensions of the block, which is favorable for a good mechanical content of the assembly. Such a generally rectangular parallelapped shape makes the block easy to handle but also lodged in a settling tank. As already mentioned above, the block is advantageously placed in the center of the system in such a way that the plates are vertical, with the first edge extending horizontally; which notably allows the block to be suspended in a fixed part of the system, without subjecting a deformation of the block due to gravity. In this configuration, it can be observed that the decanting is done along a locally triangular portion (in a zone of union between the two plates), which is favorable for a rapid evacuation of decanted sludge. The blocks are constituted by the grouping of a certain number of modules, each block being able to be provided with hooks or rings in order to facilitate their maintenance. The assembly of the modules in order to constitute a block can be carried out by subjection, adhesion, thermal welding or ultrasound. The blocks can also be installed inside the metal frames or not, the frame can also serve the transport as well as the maintenance. Advantageously, the frame can be removable in order to allow an easy replacement of the sheets, according to the needs of the treatment. The arrangement of the blocks in the extension one of the other, needs the respect of the same orientation of decanting tubes in order to ensure that the end tubes of one of the blocks is in the extension of the corresponding tubes of the other block; Two-piece tubes are thus obtained, which are finally the same length as the tubes completely contained in each block. It has a modular structure that allows to adapt easily to the particular arrangement of the tank that must comprise the system of laminar decantation, this tank can be of any shape and of any size, by placing the blocks in the openings of the treatment in the provided supports for this purpose or suspended in existing structures, by mechanical maintenance only.

When the block is confronted with a wall of tub to which the plates are perpendicular, this block advantageously is placed at a distance from this wall in order to allow a space to subsist between the sheets and the walls, in order to ensure the feeding and the Drainage of the decantation tubes of this block that are incomplete. Preferably, the tubes have a hydraulic diameter comprised between 40 and 100 mm, and / or the tubes have a length comprised between 15 and 30 times their hydraulic diameter, which ensures good decantation performances. It can be seen that, with respect to the blocks of US-A-5,384, 178, the modules and blocks of the invention lead to a greater lightness, for a given volume, without harming the mechanical content of the assembly, with the tubes of more important section, with less risk of plugging, since there are no plates approximately flat between the plates that have important undulations. The arrangement of the invention allows the use, for a given settling work, of a surface of plates greatly inferior to that proposed by the aforementioned document, the flat plates not playing a role in the actual decanting. The parallel arrangement of corrugations (or embossing), in contrast to the cross-shaped trimmings, minimizes turbulence and avoids the constitution of mixing platforms. The present blocks significantly facilitate employment and can be installed in an appliance without emptying or stopping its operation. V. DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS OF THE INVENTION Objects, characteristics and advantages of the invention result from the following description, provided by way of illustrative non-limiting example with respect to the attached drawings in which: Figure 1 is a view in perspective of a laminar decanting module, figure 2 is a laminar decanting block according to the invention, figure 3 is a partial view of the upper part of this block, - figure 4 is a detailed view of a tube of decanting in vertical section, in service configuration, figure 5 is a block diagram of a block such as that of figures 2 and 3, provided with fastening elements, figure 6 is a top view showing an assembly of blocks, complete or incomplete, occupying a predetermined rectangular space, Figure 7 is a schematic diagram showing the cooperation of two blocks located in the prolongation one of the other, in the center of the system of figure 6, figure 8 is a diagram of the principle of an installation comprising a decantation system placed on supports, figure 9 is a schematic of the principle of another installation comprising a system of complete decanting in a tank of activated sludge of the channel type, - Figure 10 is a diagram of the principle of another installation comprising a series of decanting blocks, placed against a curved wall, Figure 1 1 is a vertical section of this installation, and - Figure 12 is a schematic of the principle of another installation, suspended. This module, designated under the general reference 1, comprises two plates 2 and 3 fixed to each other, for example, by adhesion. These two plates comprise corrugations of which the crests 2A or 3A and the valleys 2B or 3B are inclined with respect to a first edge of these plates at a non-zero angle; these valleys are fixed to each other, while the crests of two plates delimit the inclined settling tubes 4. These two plates have the same profile and are fixed in their valleys and zones that define an active plane P which is a plane of symmetry for the tubes defined by these plates. These plates are here identical, in this sense, notably, in that their edges are in front; they are symmetrical with each other with respect to the plane P. Their shape is rectangular pre-reference, which is a particularly simple form. As it is represented in figure 2, several plates can be assembled in such a way as to form a block 10, here globally rectangular parallelepiped, with a network of identical hexagonal tubes. The block of Figure 3 can advantageously be analyzed as being formed of four modules 1 such as that of Figure 1, but the number of modules per block can surely be different. The valleys of the plates form the 4 'tubes, here similar to those formed in the center of each module. In effect, the ridges and valleys here are chosen with the same profile, so that the tubes formed together by the ridges of two plates shown side by side are identical to the tubes formed together by the valleys of these plates with the valleys of each of the plates that its front side. The aforementioned laminar documentation system is based on the principle of V decanting, using one of the corners of the hexagonal section inclined tube 4. The main advantage with respect to the classic arrangement where the decanting takes place on one side of the hexagon, is to have a lower rubbing surface between mud and walls, which leads to a decrease in friction forces that slow down normally the offspring of the sludge in the tube and of which it has an increase in the speed of spillage. This has the consequence that, to evacuate the same volume of sludge, the thickness of the layer is lower, dragging an increase of the section available for the spill of water, which has a lower ascending speed and a better efficiency of separation. This will stand out particularly well in FIG. 4. The tubular structure of the present blocks compared to the flat plates is characterized by an upper hydraulic diameter, a lower Reynolds number as well as a reduced length for the establishment of laminar spillage (NB: these notions are well known to the person skilled in the art, the diameter being for example the quadruple of the hydraulic radius, which is the ratio of the wet section (section occupied by the spill) in the wet perimeter: these notions are, for example , defined in Armando Lencaster's General Hydraulic Manual, Ediciones Eyrolles, 1986, p.50). This results in a more effective effective length than for a flat plate decanter, of which separation efficiency exceeds the identical total length and spacing. The following table allows a comparison between a block according to the invention and a system of flat plates: The separation of the tubes, that is to say their hydraulic diameter, may be chosen according to the quantity of sludge to be extracted and the desired concentration at the outlet. The separation will be preferably more important for heavily loaded waters that comprise a significant risk of plugging, and conversely, lower when seeking to increase treatment efficiency. Thus, the hydraulic diameter will preferably be chosen between 30 and 100 mm, preferably between approximately 40 mm for low-loaded water, approximately 80 mm for loaded water. Several warnings can be made about the blocks (of which some have already been mentioned), reminding them that they deal with specific characteristics, but not imperatives.

Decanting plates of rectangular shape are preferably provided with channels or embossments, for example formed by thermoforming; this term "embossed" may seem more appropriate than that of undulation when the section of valleys or ridges is polygonal. These embossings advantageously form an angle with respect to the base comprised between 45 to 65 °, preferably between 55 ° and 60 °. The height of the plates is typically between 500 mm and 3000 mm, preferably between 900 mm and 1300 mm. The thermoformed channels are preferably trapezoidal in order to create closed hexagonal shapes when building modules. Each module is made up of two parallel plates, placed in mirror with respect to their contact plane. Each block is constituted of a predefined number of modules placed in parallel (same that in variant it will be able to have an odd number of identical plates, mounted successively feet against head). The length B of each block depends on the number of associated modules and takes into account the length of the opening to be equipped, including the packaging mode provided for transport. The blocks are of a parelalapipédica form in order to facilitate the installation in all the dimensions and forms of opening; the last block of a range can be shortened taking into account the length of the opening to be equipped.

Each block can be provided with hooks 5 (cf figure 5), for example, number four, in order to facilitate maintenance (placement and dislocation) when the initial installation or for washing or replacement. These hooks are placed here along the upper edges of two end plates of the block. It can be seen here that the plates extend according to the largest dimension of the block, and that the width of this block (the depth in this figure 5) is perpendicular to the plates. The number of blocks to be placed in parallel as well as their width are defined according to the width of the settling tank. Several blocks can be juxtaposed in the longitudinal direction, depending on the total length of the tank and the length of each block. Figure 6 shows an arrangement of 12 modules, of which 2x3 are complete modules (of dimensions LXB), three modules of reduced width (width L less width B1), three modules of reduced width (width L1 with width B) and a reduced module on two dimensions (width L1 and width B1). It can be seen that the blocks are contiguous, and that consequently the tubes of these blocks extend one another (see figure 7). Indeed, the lateral decoupling of each plate is advantageously carried out systemically at the same point with respect to the trapezoidal profile in order to ensure a perfect continuity between two longitudinally placed blocks. The continuity of spillage in the decantation tubes belonging to the successive blocks are thus ensured by avoiding their eventual plugging by the sides deposited and not evacuated, which is schematized by the two arrows of figure 7 that cross the interface between the two adjacent blocks. So that will stand out notably from Figure 8, in a rectangular decanter, of vertical circulation spaces. And they can be advantageously arranged between the last block and the wall of the tub in order to ensure the use of all the decanting tubes and thus avoid the formation of deposits in the tubes. It can be seen that this rectangular decanter is simply placed in the holders 20. In a rectangular decanter such as that of FIG. 8, the horizontal plates (here represented under the same references as the holders 20) are placed at the side or underneath. each vertical conveyor in order to separate the raw water from the decanted water. Figure 9 represents a rectangular decanter shown in a channel of active sludge, here suspended (for example, by means of hooks 5 of figure 5) to a leaf structure 25 under-weighing the water level but being able, in variety, to be placed. A radiator is represented under reference 40. Figure 10 represents a circular decanter, equipped with a succession of blocks 10 mounted after the wall, in front of the outlet weir (not shown), as well as that will appear in figure 11, each block is, for example, placed on supports 15. And Figure 12 represents in section a decanter comprising two blocks on each side of a rectilinear channel 30 (in a configuration suspended here).

Claims (23)

1. CLAIMS 1. Laminar settling module, comprising two plates fixed to each other, at least one of these plates comprising undulations of which the ridges and valleys are inclined with respect to a first edge of this plate according to a non-zero angle and delimiting with the other the plates of inclined decant tubes, characterized in that the two plates (2, 3) have the same corrugated profile and are fixed to each other in the bonding areas defining a plane of symmetry (P) for the tubes (4) defined by these plates. Module according to claim 1, characterized in that the inclination angle (a) is comprised in the range of 45 ° -65 °. Module according to claim 2, characterized in that the inclination angle is comprised in the range of 55 ° -60 °. 4. Module according to any of claims 1 to 3, characterized in that the crests (2A, 3A) and the valleys (2B, 3B) have a trapezoidal shape, so that the decanting tubes have a hexagonal shape. Module according to any of claims 1 to 4, characterized in that the crests and the valleys have identical profiles. Module according to any of claims 1 to 5, characterized in that the two plates are symmetrical with respect to the plane of symmetry of tubes. 7. Module according to any of claims 1 to 6, characterized in that the plates are identical to each other. 8. Module according to any of claims 1 to 7, characterized in that the plates have a rectangular shape. Module according to any of claims 1 to 8, characterized in that the tubes are rectilinear over their entire length. 10. Laminar settling system comprising at least one block (10) formed of several plates, of which at least one pair constitutes a module according to any of claims 1 to 9. 1 1. The system according to claim 10, characterized in that the block (10) comprises at least two modules assembled in such a way that these modules jointly delimit other tubes (4 '), these modules being fixed to each other in zones that define a plane of symmetry for these other tubes. System according to claim 1, characterized in that the other tubes (4 ') have the same section as the tubes (4) of each module. System according to any of claims 1 to 12, characterized in that the modules are identical to each other. System according to any of claims 10 to 13, characterized in that the block has a rectangular parallelapped shape, the plates being parallel to one of the sides of this block. 15. System according to claim 14, characterized because the plates extend perpendicularly to the smallest dimension of the block. 16. System according to any of claims 10 to 15, characterized in that the block is placed so that the plates are vertical and the first horizontal edge. System according to claim 16, characterized in that this block is provided with fastening elements by means of which this block can be maintained. System according to claim 17, characterized in that the block is suspended in a fixed part of the system. System according to any of claims 10 to 16, characterized in that the block is placed in a fixed part of the system. System according to any of claims 10 to 19, characterized in that it comprises at least two juxtaposed and identical blocks, in such a way that the tubes of one of the blocks is in the extension of the tubes of the other of the blocks. System according to any of claims 10 to 20, characterized in that the block is placed next to a wall of the tank to which the plates are perpendicular, leaving a space between this block and this wall. 22. System according to any of claims 10 to 21, characterized in that the tubes have a hydraulic diameter comprised between 40 and 100 mm. 23. System according to any of claims 10 to 22, characterized in that the tubes have a width comprised between 15 and 30 times their hydraulic diameter.